Patent Application
20140267482
The device and method disclosed in this document relate to inkjet printers generally and, more particularly, to devices and methods for applying release agent to continuous feed media to facilitate finishing operations.
Inkjet printers have printheads that operate a plurality of inkjets that eject liquid ink onto an image receiving surface. The ink can be stored in reservoirs positioned within in the printer. Such ink may be aqueous, oil, solvent-based, or UV curable ink or an ink emulsion. Other inkjet printers receive ink in a solid form and then melt the solid ink to generate liquid ink for ejection onto the image receiving surface. In these solid ink printers, the solid ink can be in the form of pellets, ink sticks, granules or other shapes. Typically, an ink loader delivers solid ink pellets or ink sticks placed in the ink loader through a feed chute or channel to a melting device. A reservoir receives the melted ink and supplies the melted ink to one or more printheads. Other inkjet printers use gel ink. Gel inks are also heated to a predetermined temperature to alter the viscosity of the ink so the ink is suitable for ejection by a printhead.
A typical full width scan inkjet printer uses one or more printheads. Each printhead typically contains an array of individual nozzles for ejecting drops of ink across an open gap to an image receiving surface to form an image. The image receiving surface can be the surface of a continuous web of recording media, the surfaces of a series of media sheets, or the surface of an image receiving member, such as a rotating print drum or endless belt. Mechanical force is often used to fix images printed on a continuous web. A spreader nip produces the mechanical force with a pair of rollers configured to apply heat and pressure to the media web.
Continuous feed solid inkjet (SIJ) printers often print roll-to-roll, meaning the printers form images on the media web and then store the imaged media web on a roll for subsequent processing on offline finishing equipment. Such finishing equipment can include devices for, among other things, converting the web into individual sheets, perforating or punching holes into the web, or folding or creasing the web or the converted sheets.
Existing high-speed offline finishing operations, such as conversion into individual sheets, can cause image damage and/or ink offsetting to equipment surfaces. For existing continuous feed SIJ output, this image damage or ink offset can be attributed to insufficient amounts of release agent remaining on the imaged portions of the web. Moreover, the relatively long duration of time between imaging operations and offline finishing operations allows the imaged area to absorb what little release agent remains on its surface. The insufficient amount of release agent on the imaged area enables ink to offset from the web to surfaces of the finishing equipment that contact the imaged area, degrading the performance of the finishing equipment and the quality of the finished image. Systems exist for applying release agent to an imaged media web prior to performing further finishing operations. However, such systems apply release agent to the entire surface of the imaged area without consideration as to whether a given surface of the web is susceptible to ink offset. Consequently, these systems distribute more release agent than necessary since only those areas of a web susceptible to ink offset require treatment. Therefore, efficient application of release agent to imaged areas is desirable.
A release agent applicator module has been developed for applying release agent to a web having a sequence of printed images on a first surface. The module includes a plurality of dispensers arranged in a cross-process direction across the web as the web moves in a process direction that is perpendicular to the cross-process direction, the process direction and the cross-process direction defining a plane that is parallel to the first surface of the web as the first surface of the web passes in front of the plurality of dispensers, each dispenser being configured for selective operation to dispense release agent onto a portion of the first surface of the web opposite the dispenser, and a controller operatively connected to each dispenser in the plurality of dispensers, the controller being configured to operate each dispenser with reference to a position of the first surface of the web and a content of each printed image in the sequence of printed images associated with the position of the first surface of the web.
A method for applying release agent to a web having a sequence of printed images on a first surface has been developed. The method includes moving the web in a process direction past a plurality of dispensers arranged across the web in a cross-process direction perpendicular to the process direction, the process direction and the cross-process direction defining a plane that is parallel to the first surface of the web as the first surface of the web passes in front of the plurality of dispensers, and selectively operating each dispenser in the plurality of dispensers to dispense release agent onto a portion of the first surface of the web opposite the dispenser, each dispenser being operated with reference to a position of the first surface of the web and a content of each printed image in the sequence of printed images.
The foregoing aspects and other features of the device and method for addressable spray-on application of release agent to a continuous feed media are explained in the following description, taken in connection with the accompanying drawings.
For a general understanding of the environment for the device and method disclosed herein as well as the details for the device and method, reference is made to the drawings. In the drawings, like reference numerals designate like elements. As used herein, the word “printer” encompasses any apparatus that produces images with colorants on media, such as digital copiers, bookmaking machines, facsimile machines, multi-function machines, and the like. As used herein, the term “process direction” refers to a direction of movement of a print medium, such as a continuous media web pulled from a roll of paper or other suitable print medium along a media path through a printer. The print medium moves past one or more printheads in a print zone within the printer to receive ink images and then pass other printer components, such as heaters, fusers, pressure rollers, and on-sheet imaging sensors, that are arranged along the media path. As used herein, the term “cross-process” direction refers to an axis that is perpendicular to the process direction along the surface of the print medium.
As used herein, the terms “finisher,” “finishing equipment,” “conversion equipment,” or the like encompass any device or devices that perform processing or “finishing” of the print medium after ink images are formed on the medium. Such devices, for example, can separate the continuous media web into individual cut sheets, apply perforations to the print medium, and bend or crease the printed medium. As used herein, the term “inline” used in describing a type of finisher or finishing process refers to finishing operations performed either by the printer or by a device or devices upstream or downstream of the printer. In inline finishing, the finishing operations are performed close in time with the imaging operations and rewinding and storing of the print medium for later processing is often unnecessary. As used herein, the term “offline” used in describing a type of finisher or finishing process refers to finishing operations performed by a device or devices after an imaged continuous media web is rewound and transported to the finishing device or devices.
The printer 5 includes a controller 50 to process the image data before generating the control signals for the inkjet ejectors to eject colorants. Colorants can be ink or any suitable substance, which includes one or more dyes or pigments and which is applied to the media. The colorant can be black or any other desired color, and some printer configurations apply a plurality of different colorants to the media. The media includes any of a variety of substrates, including plain paper, coated paper, glossy paper, or transparencies, among others, and the media can be available in sheets, rolls, or other physical formats.
The printer 5 is an example of a direct-to-web, continuous-media, phase-change inkjet printer that includes a media supply and handling system configured to supply a long (i.e., substantially continuous) web of media 14 of “substrate” (paper, plastic, or other printable material) from a media source, such as a spool of media 10 mounted on a web roller 8. The media web 14 includes a large number (e.g. thousands or tens of thousands) of individual pages separated into individual sheets with commercially available finishing devices after completion of the printing process.
For duplex operations, the web inverter 84 flips the media web 14 over to present a second side of the media to the print zone 20, before being taken up by the rewind unit 90. In duplex operation, the media source is approximately one-half of the width of the rollers over which the web travels so the web covers less than one-half of the surface of each roller 26 in the print zone 20. The inverter 84 flips and laterally displaces the media web 14 and the media web 14 subsequently travels over the other half of the surface of each roller 26 opposite the print zone 20, for printing and fixing of the reverse side of the media web 14. During first-side printing in the print zone 20, a first plurality of printheads in each of the printhead units 21A-21D forms a first side image on the media web 14 during a first pass through the print zone 20 and the spreader 40. The web inverter 84 inverts and re-routes the second side of the media web 14 through a second plurality of printheads in each of the printhead units 21A-21D during a second pass through the print zone 20 and the spreader 40. Thus, the second pass of the media web is downstream of the first pass through print zone 20, which includes both a first group of printheads that print on the first side the media web 14 and a second group of printheads that print on the second side of the media web 14. The rewind unit 90 is configured to wind the web onto a roller for removal of the media web from the printer and subsequent processing. Still referring to
The controller 50 of the printer 5 receives velocity data from encoders mounted proximately to the rollers positioned on either side of the portion of the path opposite the four printheads to calculate the linear velocity and position of the web as the web moves past the printheads. The controller 50 uses the media web velocity data to generate firing signals for actuating the inkjet ejectors in the printheads to enable the printheads to eject four colors of ink with appropriate timing and accuracy for registration of the differently colored patterns to form color images on the media. The inkjet ejectors actuated by the firing signals correspond to digital data processed by the controller 50. The digital data for the images to be printed can be transmitted to the printer, generated by a scanner (not shown) that is a component of the printer, or otherwise generated and delivered to the printer.
Associated with each printhead unit is a backing member 24A-24D, typically in the form of a bar or roll, which is arranged substantially opposite the printhead on the back side of the media. Each backing member positions the media at a predetermined distance from the printhead opposite the backing member. As the partially-imaged media web 14 moves to receive inks of various colors from the printheads of the print zone 20, the printer 5 maintains the temperature of the media web 14 within a given range. The printheads in the printhead units 21A-21D eject ink at a temperature typically significantly higher than the temperature of the media web 14. Consequently, the ink heats the media, and temperature control devices maintain the media web temperature within a predetermined range. For example, the air temperature and air flow rate behind and in front of the media web 14 impacts the media temperature. Accordingly, in some embodiments, air blowers or fans are utilized to facilitate control of the media temperature. Thus, the printer 5 maintains the temperature of the media web 14 within an appropriate range for the jetting of all inks from the printheads of the print zone 20. Temperature sensors (not shown) in some embodiments are positioned along this portion of the media path to enable regulation of the media temperature.
Following the print zone 20 along the media path is a fixing assembly 40 that applies heat and/or pressure to the media to fix the images to the media. The fixing assembly includes any suitable device or apparatus for fixing images to the media including heated or unheated pressure rollers, radiant heaters, heat lamps, and the like. In the embodiment depicted in
The spreader 40 can include a cleaning/oiling station 48 associated with image-side roller 42. The station 48 cleans and/or applies a layer of some release agent or other material to the roller surface. The release agent material can be an amino silicone oil having viscosity of about 10-200 centipoise. A small amount of oil transfers from the station to the media web 14, with the printer 5 transferring approximately 1-10 mg per A4 sheet-sized portion of the media web 14. In one embodiment, the media is maintained at a high temperature as the media exits the print zone 20 to enable spreading of the ink. The printer 5 also includes an optical sensor 54 that is configured to generate image data of the media web 14 as discussed in more detail below.
In printer 5, the controller 50 is operatively connected to various subsystems and components to regulate and control operation of the printer 5. The controller 50 is implemented with general or specialized programmable processors that execute programmed instructions. The instructions and data required to perform the programmed functions are stored in a memory 52 that is associated with the controller 50. The memory 52 stores programmed instructions for the controller 50. The processors, their memories, and interface circuitry configure the controllers and/or print zone to perform the printer operations. These components can be provided on a printed circuit card or provided as a circuit in an application specific integrated circuit (ASIC). Each of the circuits can be implemented with a separate processor or multiple circuits can be implemented on the same processor. Alternatively, the circuits can be implemented with discrete components or circuits provided in VLSI circuits. Also, the circuits described herein can be implemented with a combination of processors, ASICs, discrete components, or VLSI circuits. The controller 50 is operatively connected to the printheads in the printhead units 21A-21D. The controller 50 generates electrical firing signals to operate the individual inkjets in the printhead units 21A-21D to eject ink drops that form printed images on the media web 14.
After simplex, or optional duplex, printing operations, the media web 14 is wound onto the roller of the rewind unit 90 for removal from the printer 5 and subsequent processing. Such processing often includes conversion of the printed media web into individual cut sheets, sometimes called “sheeting,” to enable final distribution of the printed substrate. Printing systems that use aqueous, emulsified, and other types of ink can produce images on media that experience ink offsetting during offline conversion, but the offsetting occurs for reasons other than an inadequate amount of release agent since these systems do not use release agent in the printing process. Existing continuous feed SIJ systems, however, perform inadequately with offline conversion because an insufficient amount of release agent remains on the surface of the image after the ink spreading operation. During conversion of existing continuous feed SIJ output, for example, insufficient amounts of residual release agent on the surface of the image can result in ink offsetting to surfaces of the converting equipment, resulting in degraded performance of the finishing equipment and poor quality of the finished image. The relatively long duration of time between printing operations and offline finishing operations further exacerbates this degraded performance and poor image quality.
The release agent applicator module 100 includes a plurality of dispensers 114 arranged in the cross-process direction 110 across the web 14. A finisher transport system (not shown) moves the simplex-imaged web 14 past the release agent applicator module 100 in a process direction 116 that is perpendicular to the cross-process direction 110. The process direction 116 and the cross-process direction 110 define a plane that is approximately parallel to the first surface 106 of the web 14 as the first surface 106 of the web 14 passes in front of the plurality of dispensers 114. Each dispenser 114 is configured to dispense the release agent selectively onto a portion of the first surface 106 of the web 14 opposite the dispenser 114.
Referring now to
The nozzle 118 of each dispenser 114 has a body 128 that defines a plurality of fluid chambers within the nozzle 118. The compressed air and the release agent are delivered from their respective sources 122, 124 to an inlet orifice 130 of the nozzle 118. The compressed air and the release agent then enter a swirl core 132 and a swirl chamber 134 where the release agent is atomized. The atomized release agent exits the nozzle 118 at an outlet orifice opening 136, which directs the release agent towards the web 14. In some embodiments, characteristics of the outlet orifice 136, such as orifice area, shape, or axial taper, can be varied to adjust the direction or shape of the release agent spray 120.
In one embodiment, the release agent is a silicon-based oil having a small amount of functional amine, for example, 0.5 percent amine. One example of such an oil is CopyAid 270. The chemical composition of CopyAid 270 is described as a Polydimethylsiloxane+Polydimethylsiloxane with aminoalkyl groups. Although CopyAid 270 is approximately 70-centistoke viscosity, other types of oils, particularly ones with lower viscosities, can be used for the same purpose. In the embodiment using CopyAid 270, the oil is applied at a rate of 4-50 mg per A4 sheet-sized portion of the web 14 with a minimum rate of approximately 4-8 mg per A4 (ink solid fill).
Referring to
Referring again to
The module 100 further includes a controller 142 operatively connected to the optical sensor 140 and to each dispenser in the plurality of dispensers 114 via a solenoid valve 144. The controller 142 is implemented with general or specialized programmable processors that execute programmed instructions. The instructions and data required to perform the programmed functions are stored in a memory that is associated with the controller 142. In response to the controller 142 executing the programmed instructions, the controller identifies positions and boundaries of areas on the web that are covered by an amount of ink that equals or exceeds a predetermined density threshold. The controller operates each dispenser 114 with reference to the positions and boundaries identified on the first surface 106 of the web 14. If the controller identifies an area on the web as meeting or exceeding the predetermined density threshold, the controller 142 sends a signal to the solenoid valve 144 to operate a dispenser 114 as the identified area passes the dispenser. The controller operates the solenoid valve 144 of the dispenser to dispense release agent onto the first surface 106 of the web 14 opposite the dispenser 114 as the identified area passes the dispenser. The association of each dispenser 114 with a discrete section 146 across the first surface 106 of the web 14 enables the module 100 to apply release agent only to those sections 146 of the first surface 106 of the web 14 containing portions of the printed images 104 that meet or exceed the predetermined threshold. As discussed below, the selective addressability of the release agent has positive implications for printing systems that employ offline finishing operations.
For the selective application of the release agent onto the first surface 106 of the web 14, the release agent applicator module 200 includes the plurality of dispensers 114, the optical sensor 140, and the controller 142 as described above with reference to
The finisher transport system (not shown) moves the duplex-imaged web 14 in the process direction 116 past the plurality of dispensers 114 and the second plurality of dispensers 114′. The process direction 116 and the cross-process direction 110 define a plane that is approximately parallel to the second surface 148 of the web 14 as the second surface 148 of the web 14 passes in front of the second plurality of dispensers 114′. Each second dispenser 114′ is configured to dispense the release agent onto a portion of the second surface 148 of the web 14 opposite the second dispenser 114′ in response to a signal from the controller operating the dispenser. Each dispenser in the second plurality of dispensers 114′ is configured to mix compressed air and release agent to atomize the release agent into an atomized spray or mist 120′ directed toward the passing web 14 as noted above with reference to the first plurality of dispensers.
An enclosure member 150 surrounds the plurality of dispensers 114 and the second plurality of dispensers 114′ and closely seals with the passing web 14 to collect release agent that does not land on either or both of the first and second surfaces 106, 148 of the web 14. In some embodiments a vacuum system similar to the one described above generates a vacuum within the enclosure member 150 to collect atomized release agent not landing on the web. Exhaust from the vacuum system is filtered to prevent airborne egress of the collected release agent from the release agent applicator module 200.
The second optical sensor 140′ is configured in a manner similar to the optical sensor 140 described above. The controller 142 analyzes the digital image data generated with reference to the image data from sensor 140′ and operates each dispenser in the second plurality of dispensers 114′ selectively with reference to that data. The controller 142 selectively generates signals to operate solenoid valves in the dispensers of the second plurality of dispensers as described above with regard to the first plurality of dispensers.
Although the release agent applicator module 200 has been described with reference to the application of release agent to duplex-imaged webs, the module 200 can similarly be operated to selectively apply release agent to simplex-imaged webs. In this embodiment, only the dispensers opposite the surface of the web containing printed images are selectively operated by the controller to apply release agent. The dispensers opposite the non-imaged or blank surface of the simplex-imaged web are not operated to dispense release agent. In some embodiments, the dispensers opposite the blank surface are placed in an IDLE or OFF state and are incapable of receiving control signals from the controller while in this state. In other embodiments, the dispensers are enabled and capable of dispensing release agent; however, the controller does not provide the activation signal to operate the dispensers.
Each of the modules 802, 804, and 806 includes a transport system (not shown) including various rollers, hardware, and the like to move the web 14 through the modules. As such, ink offsetting/smearing can occur in the modules 802, 804, and 806 if any surfaces of their respective transport systems come into contact with printed surfaces on the web 14 having insufficient amounts of release agent thereon. To mitigate ink offsetting/smearing during offline finishing operations, the release agent applicator module 100, 200 is integrated with the finishing system 800, 900 to selectively apply release agent to the printed surfaces of the web 14 early in the finishing process. Although the finishing system 800, 900 has been described with reference to specific finishing devices, other combinations of finishing devices can be implemented. For example, the finishing system 800, 900 can also include, among others, cross cutting modules, web inspection modules, buffering modules, folding/merging modules, and/or stacking modules.
A flow diagram of a process 300 for selectively applying release agent to a web having a sequence of printed images on a first surface 106 is shown in
The process 300 begins by moving the imaged web 14 in the process direction 116 past the plurality of dispensers 114 (block 302). As the web 14 moves in the process direction 116, the optical sensor 140 is operated to generate image data of the first surface 106 of the web 14 (block 304). The process 300 divides the image data into respective sections that correspond to each dispenser in the plurality of dispensers 114 (block 306). The sections of image data correspond to the discrete areas 146 across the web 14 in the cross-process direction 110 onto which the dispensers 114 are configured to apply release agent. Accordingly, the number of dispensers in the plurality of dispensers 114 determines the number of sections into which the image data is divided.
The process 300 evaluates the image data generated by the optical sensor 140 to identify the positions and boundaries of the printed images 104 in the sequence of printed images 102 (block 308). In particular, the process 300 analyzes the image data to identify areas in which the density of the ink meets or exceeds a predetermined density threshold. The process 300 then determines whether the identified areas are positioned within the corresponding area 146 on the web 14 and, therefore, are capable of receiving release agent from the dispenser 114 associated with the area (block 310).
For each image area associated with an area 146, the process 300 activates the dispenser 114 associated with the area to dispense the release agent onto the surface 106 of the web 14 opposite the dispenser 114 (block 312). In operation, the controller 142 sends a signal to the solenoid valve 144 associated with the dispenser 114 to operate the dispenser 114 to dispense the release agent. The process 300 periodically evaluates the digital image data and updates the signal to the solenoid valve 144. For example, in one embodiment, the solenoid valve 144 is configured to operate its associated dispenser 114 for a predetermined duration of time upon receipt of a signal. In this embodiment, if the solenoid valve 144 does not receive a new signal indicating the presence of printed images 104 opposite the dispenser 114, the solenoid valve 144 disables the dispenser 114 to prevent release agent from being dispensed. In another embodiment, the solenoid valve 144, upon receipt of a signal indicating the presence of printed images 104 opposite the dispenser 114, is configured to continuously operate the dispenser 114 until a deactivation signal is provided. In this embodiment, the process 300 deactivates the dispenser 114 associated with an area in response to no image area being identified for the area opposite a dispenser (block 314).
After a dispenser is either activated (block 312) or deactivated (block 314), the process 300 determines whether another portion the web 14 will pass the plurality of dispensers 114 (block 316). If the web is continuing, the process 300 continues to determine for another area contains a printed image 104 (block 310). If no additional areas are identified, the process 300 ends (block 318). For selective application of release agent to a duplex imaged web, movement of web 14 in the process direction 116 (block 302) moves the web 14 past both the plurality of dispensers 114 and the second plurality of dispensers 114′ (
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art that are also intended to be encompassed by the following claims.
