STEAM TREATMENT DEVICE COMPRISING A CONVEYOR FOR PRINT MEDIA

Abstract

Deformation is reduced or prevented in a printed print medium during steam treatment by a print medium treatment device for a printer. The print medium treatment device includes a steam treatment unit for treating a first side of a print medium with steam, the steam treatment unit including a steam generator connectable to a steam chamber; and a conveyor for transporting the print medium through the steam chamber. The conveyor includes a holding device for engaging a second side of the print medium opposite the first side, such that the print medium is flattened against the conveyor.

Claims

1. A print medium treatment device for a printer comprising: a steam treatment unit for treating a first side of a print medium with steam, the steam treatment unit comprising a steam generator connectable to a steam chamber; and a conveyor for transporting the print medium through the steam chamber, the conveyor comprising a holding device for engaging a second side of the print medium opposite the first side, such that the print medium is flattened against the conveyor.

2. The print medium treatment device according to claim 1, wherein the holding device is positioned partially within the conveyor.

3. The print medium treatment device according to claim 1, wherein the conveyor defines a substantially flat medium support plane, and wherein the second side of the print medium faces the medium support plane when the print medium is on the conveyor.

4. The print medium treatment device according to claim 3, wherein the holding device is configured to engage the print medium through the medium support plane.

5. The print medium treatment device according to claim 2, wherein the conveyor comprises an endless, air permeable transport belt.

6. The print medium treatment device according to claim 5, wherein the steam treatment unit comprises a housing defining the steam chamber, and wherein the transport belt is positioned inside the housing.

7. The print medium treatment device according to claim 6, wherein the transport belt is positioned fully inside the housing.

8. The print medium treatment device according to claim 5, wherein the holding device comprises a suction device for applying a negative pressure to the second side of the print medium.

9. The print medium treatment device according to claim 8, wherein the holding device further comprises a suction source in fluid connection to a suction chamber, the suction chamber being positioned adjacent the transport belt.

10. The print medium treatment device according to claim 9, wherein the suction source is further in fluid connection to a steam return channel, such that steam which has been sucked into the suction chamber may be returned to the steam chamber via the steam return channel.

11. The print medium treatment device according to claim 10, wherein the steam return channel is in fluid connection to a steam supply channel which is arranged to supply steam from the steam generator to the steam chamber.

12. The print medium treatment device according to claim 11, further comprising an atmospheric sensor positioned inside the steam chamber for detecting at least one atmospheric condition, wherein a controller is configured to control the steam generator based upon the detected at least one atmospheric condition.

13. The print medium treatment device according to claim 7, wherein a drive for driving the conveyor is positioned outside the steam chamber.

14. The print medium treatment device according to claim 1, wherein the steam generator is a superheated steam generator configured for generating steam at a temperature higher than a vaporization point thereof at an absolute pressure where the temperature is measured.

15. The print medium treatment device according to claim 14, further comprising a controller storing a media catalogue, wherein an operational range for the steam generator has been defined for each print medium in the media catalogue.

16. A printer comprising the print medium treatment device according to claim 1.

17. A method for treating a print medium in the printer according to claim 1, comprising the steps of: transporting the print medium held onto a conveyor by means of a negative pressure through a steam chamber, wherein the print medium is exposed to steam; and returning at least a portion of steam sucked from the steam chamber by means of the negative pressure back to the steam chamber.

18. The method according to claim 17, wherein steam is applied to a first side of a print medium facing away from the conveyor and the print medium is held onto the conveyor by a holding device engaging only a second side of the print medium opposite the first side.

19. The print medium treatment device according to claim 11, further comprising an atmospheric sensor positioned inside the steam chamber for detecting at least one atmospheric condition, wherein a controller is configured to control the steam generator based upon the detected at least one atmospheric condition, and wherein the at least one atmospheric condition is pressure, oxygen level, temperature, or humidity level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0029] FIG. 1 is a schematic, side view of an inkjet sheet printer; and

[0030] FIG. 2 is a schematic, cross-sectional view of a print medium treatment device of the printer in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views.

[0032] FIG. 1 shows schematically an embodiment of a printing system 1 according to the present invention. The printing system 1, for purposes of explanation, is divided into an output section 5, a print engine and control section 3, a local user interface 7 and an input section 4. While a specific printing system is shown and described, the disclosed embodiments may be used with other types of printing system such as an ink jet print system, an electrographic print system, etc.

[0033] The output section 5 comprises a first output holder 52 for holding printed print medium, for example a plurality of sheets. The output section 5 may comprise a second output holder 55. While 2 output holders are illustrated in FIG. 1, the number of output holders may include one, two, three or more output holders. The printed print medium is transported from the print engine and control section 3 via an inlet 53 to the output section 5. When a stack ejection command is invoked by the controller 37 for the first output holder 52, first guiding means 54 are activated in order to eject the plurality of sheets in the first output holder 52 outwards to a first external output holder 51. When a stack ejection command is invoked by the controller 37 for the second output holder 55, second guiding means 56 are activated in order to eject the plurality of sheets in the second output holder 55 outwards to a second external output holder 57.

[0034] The output section 5 is digitally connected by means of a cable 60 to the print engine and control section 3 for bi-directional data signal transfer.

[0035] The print engine and control section 3 comprises a print engine and a controller 37 for controlling the printing process and scheduling the plurality of sheets in a printing order before they are separated from input holder 44, 45, 46.

[0036] Resources may be recording material located in the input section 4, marking material located in a reservoir 39 near or in the print head or print assembly 31 of the print engine, or finishing material located near the print head or print assembly 31 of the print engine or located in the output section 5 (not shown).

[0037] The paper path comprises a plurality of paper path sections 32, 33, 34, 35 for transporting the print medium from an entry point 36 of the print engine and control section 3 along the print head or print assembly 31 to the inlet 53 of the output section 5. The paper path sections 32, 33, 34, 35 form a loop according to the present invention. The loop enables the printing of a duplex print job and/or a mix-plex job, i.e. a print job comprising a mix of sheets intended to be printed partially in a simplex mode and partially in a duplex mode.

[0038] The print head or print assembly 31 is suitable for ejecting and/or fixing marking material to the print medium 41. The print head or print assembly 31 is positioned near the paper path section 34. The print head or print assembly 31 may be an inkjet print head, a direct imaging toner assembly or an indirect imaging toner assembly. Downstream of the print assembly 31 a fixation unit 60 is provided along the paper path section 33. The fixation unit 60 comprises means for fixing the marking material to the print medium 41. Such means generally are arranged for rapidly transferring energy to the print medium 41 to induce a phase to dry the marking material. These means may include dryers, such as (radiation) heaters, (impingement) blowers, suction devices, etc, as commonly known in the state of the art. Downstream of the fixation unit 60 a treatment device 70 extends along the paper path section 33 to treat the print media 41 that have undergone fixation in the fixation unit 60. The treatment device 70 may be a steam treatment device arranged to expose the print medium 41 to heated or even superheated steam. Steam is known to interact favourably with the dried marking material and/or print media 41 and allows control over the final properties of the marking material and/or print media 41. For example, the glossiness level of the marking material may be controlled by steam treatment after fixation. The steam may for example be utilized to remove certain residual substances from the dried marking material, induce a reaction in the marking material, and/or adjust the humidity of the print medium.

[0039] While an print medium is transported along the paper path section 34 in a first pass in the loop, the print medium receives the marking material through the print head or print assembly 31. A next paper path section 32 is a flip unit 32 for selecting a different subsequent paper path for simplex or duplex printing of the print medium. The flip unit 32 may be also used to flip a sheet of print medium after printing in simplex mode before the sheet leaves the print engine and control section 3 via a curved section 38 of the flip unit 32 and via the inlet 53 to the output section 5. The curved section 38 of the flip unit 32 may not be present and the turning of a simplex page has to be done via another paper path section 35.

[0040] In case of duplex printing on a sheet or when the curved section 38 is not present, the sheet is transported along the loop via paper path section 35A in order to turn the sheet for enabling printing on the other side of the sheet. The sheet is transported along the paper path section 35 until it reaches a merging point 34A at which sheets entering the paper path section 34 from the entry point 36 interweave with the sheets coming from the paper path section 35. The sheets entering the paper path section 34 from the entry point 36 are starting their first pass along the print head or print assembly 31 in the loop.

[0041] The sheets coming from the paper path section 35 are starting their second pass along the print head or print assembly 31 in the loop. When a sheet has passed the print head or print assembly 31 for the second time in the second pass, the sheet is transported to the inlet 53 of the output section 5.

[0042] The input section 4 may comprise at least one input holder 44, 45, 46 for holding the print medium before transporting the sheets of print medium to the print engine and control section 3. Sheets of print medium are separated from the input holders 44, 45, 46 and guided from the input holders 44, 45, 46 by guiding means 42, 43, 47 to an outlet 36 for entrance in the print engine and control section 3. Each input holder 44, 45, 46 may be used for holding a different kind of print medium, i.e. sheets having different media properties. While 3 input holders are illustrated in FIG. 1, the number of input holders may include one, two, three or more input holders.

[0043] The local user interface 7 is suitable for displaying user interface windows for controlling the print job queue residing in the controller 37. In another embodiment a computer N1 in the network N has a user interface for displaying and controlling the print job queue of the printing system 1.

Steam treatment Device

[0044] FIG. 2 illustrates a treatment device 70 for treating print media 41 by exposure to steam. The treatment device 70 comprises a housing 71 defining a steam chamber 71C. The housing 71 is preferably sealed from the ambient environment with the exception of the openings 79, the inlet channel 86, and the outlet channel 79. The housing 71 may be further be thermally isolated to improve temperature control within the steam chamber 71C.

[0045] A steam generator 80 is provided in fluid connection to the steam chamber 71C via the inlet channel 86. The steam generator 80 comprises a liquid reservoir 82 adjacent a heater 81, so that steam may be generated and accumulated in the accumulator chamber 83. In the example in FIG. 2, the liquid reservoir 82 comprises water, which may be heated via an electric heater 81, but other steam generating means may be applied as well. Preferably, the steam generator 80 is configured to generate superheated steam, i.e. steam at a temperature higher than its vaporization point at the absolute pressure where said temperature is measured. The accumulator chamber 83 is connected to a blower 84, such as fan or pump, for driving the generated steam via the accumulator channel 85 into the inlet channel 86 and further into the steam chamber 71C. The inlet channel 86 is connected to a steam distributor 87 for distributing the steam substantially homogenously over the area of the print medium 41. Inside the steam chamber 71C an atmospheric sensor 88 is provided to detect one or more atmospheric conditions, such as (partial) pressure, humidity, temperature, etc. Data from the sensor 88 is transmitted to the controller 37, which controls the steam generator 80 based on said data. Thus, the conditions inside the steam chamber 71C may be adjusted based on a type of print medium 41 and/or the composition and/or amount of marking material on the print medium 41. Thereto, the controller stores a media catalogue, wherein for each print media type one or more parameters defining the atmospheric conditions in the steam chamber 71C have been defined. The media catalogue may be in any suitable format, such as a look-up table, algorithm, or formula.

[0046] Inside the steam chamber 71C an endless transport belt 75 of a conveyor 72A is provided. The belt 75 is movable supported on a plurality of rollers 73. At least one of the rollers 73 is connected to a drive to rotate said roller and thereby the belt 75. The drive is positioned outside the housing 71 of the steam chamber 71C, so that it is not exposed to steam. Suitable bearings may be provided in the housing to transmit a drive shaft from the drive to one of the rollers 73. Inside the steam chamber 71C the first side 41A of the print medium 41 faces away from the conveyor 72A, while the second side 41B of the print medium 41 contacts the conveyor 72A. Thereby, the first side 41A of the print medium 41 is free to be exposed to steam inside the steam chamber 71C.

[0047] The belt 75 is formed of a steam resistant material, which has been selected to withstand e.g. the high humidity and/or temperatures in the steam chamber 71C. The belt 75 may for example be formed of a suitable plastic, such as polyether ether ketone (PEEK) or any other suitable material. The belt 75 is air permeable, for example by means of a plurality of openings or through-holes provided in its surface. Below the belt a suction chamber 74 is provided in fluid connection to a suction source 77 by means of the suction channel 76 for forming a holding device 72B. Between the upper rollers 73, the belt 75 defines a print medium support plane. The suction chamber 74 may be provided with one or more support members, which contact and support the belt 75 to achieve a substantially flat print medium support plane. The side of the suction chamber 74 facing the belt 75 is open, such that gas, specifically air, may be sucked in through the openings in the belt 75 by means of the suction source 77. In this manner a negative pressure may be applied to a side of the print medium 41 facing the belt 75, such that the print medium 41 is flattened against the belt 75. The holding device 72B is preferably configured to engage the print medium 41 only at the side facing the belt 75, such that the opposite side of the print medium 41 is free from direct contact with the holding device 72B. The print medium support plane is preferably substantially flat, such that the print medium 41 is also flattened by the negative pressure parallel to said plane. Thereby, deformations in the print medium 41 during its exposure to steam are prevented, as the print medium 41 is held flat against the conveyor 72A by the holding device 72B during steam treatment: the negative pressure exerts a constant holding force on the second side of the print medium 41, keeping it flat against the belt 75. The conveyor 72A is arranged to operate at a substantially constant speed during operation, wherein print media 41 are fed into the housing 71 onto the belt 75 via one of the openings 79 and exit after steam treatment via the other of the openings 79. This allows for a highly productive printing process. In FIG. 2, the conveyor 72A and the holding device 72B are both comprised in the transport device 72.

[0048] Steam is also is sucked into the suction chamber 74 via uncovered openings in the belt 75, between and/or besides print media 41. The steam which enters the suction chamber 74 is driven by the suction source 77 via the steam return channel 78 to the inlet channel 86. There, the returned steam is mixed with freshly generated coming from the steam generator 80. By returning steam sucked in through the suction chamber 74, the loss of steam via the holding device 72B is reduced and/or prevented. This reduces the load on the steam generator 80, allowing for reduced operational and/or component costs. The steam return channel 78 may comprise a regulator, such as a valve, to adjust the flow of returned steam in the inlet channel 86. It will be appreciated that in another embodiment, the steam return channel 78 may also connect directly to an opening in the housing 71, such that it effectively forms a channel parallel to the inlet channel 86. The steam return channel 78 provides a fluid connection from the suction chamber 74 to an inlet in the housing 71, such that steam can easily be recycled by means of the suction source 77. The suction source 77 may for example be a fan or pump, preferably one configured to operate under humid conditions.

[0049] Upon entering the housing 71 via one of the openings 79, a print medium 41 is forced flat against the belt 75. The negative pressure of the suction source 77 holds the print medium 41 flat against the belt 75, so that the print medium 41 is substantially unable to deform. While fixed on the belt 75, the print medium 41 is exposed to heated steam. Print media 41, such as paper are prone to deform under humid atmospheric conditions, such as steam treatment. One example of such deformation is (local) wrinkling of the print medium 41. This deformation is however prevented, since the print medium 41 is held securely flat on the print medium support plane formed by the belt 75. In consequence, the print medium 41 and/or the marking material on it can be treated with (heated) steam with a reduced risk of deformation and/or substantially without deformation. By recycling the steam sucked in by the holding device from the steam chamber 71C back into the steam chamber 71C, the costs of such a treatment device 70 are kept relatively low.

[0050] Although specific embodiments of the invention are illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiment or exemplary embodiments are examples only and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0051] It will also be appreciated that in this document the terms comprise, comprising, include, including, contain, containing, have, having, and any variations thereof, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus or system described herein is not limited to those features or parts or elements or steps recited but may include other elements, features, parts or steps not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms a and an used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms first, second, third, etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.

[0052] The present invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.