Active device for shielding media from a heater in a printer

A printer includes a heating element and an active media shielding device configured to prevent print media from being overheated by the heating element. The shielding device includes an endless belt interposed between the print media and the heating element and configured to rotate to dissipate heat. The endless belt is arranged on, and tensioned by, two pulleys such that a portion of the endless belt is arranged nearest to the heating element and a portion of the endless belt is arranged nearest to the print media. The shielding device also includes a cleaning device configured to remove portions of print media from the endless belt.

TECHNICAL FIELD

This disclosure relates generally to printers and, specifically to printers that include media heaters.

BACKGROUND

The word “printer” as used herein encompasses any apparatus, such as a digital copier, book marking machine, facsimile machine, multi-function machine, etc., that produces an image with a colorant on recording media for any purpose. Continuous feed printers produce images on a continuous web of recording media which passes by the marking engine. Continuous feed printers also include heaters to warm the web of recording media and/or the ink which produces the images at various stages during the printing process.

By way of example,FIG. 10depicts a prior art continuous web inkjet printer800. In the embodiment shown, the printer800implements a process for printing onto a continuous media web. The continuous web printer system800includes twenty print modules880-899, a controller828, a memory829, guide rollers816, pre-heater roller818, apex roller820, leveler roller822, tension sensors852A-852B,854A-854B, and856A-856B, and velocity sensors, such as encoders860,862, and864. The print modules880-899are positioned sequentially along a media path P and form a print zone from a first print module880to a last print module899for forming images on a print medium814as the print medium814travels past the print modules. Each print module880-883provides a magenta ink. Each print module884-887provides cyan ink. Each print module888-891provides yellow ink. Each print module892-895provides black ink. Each print module896-899provides a clear ink as a finish coat. In all other respects, the print modules880-899are substantially identical. The media web travels through the media path P guided by rollers816, pre-heater roller818, apex roller820, and leveler roller822. A heated plate819is provided along the path. The pre-heater roller818, apex roller820, and leveler roller822are each examples of a capstan roller that engages the media web814on a portion of its surface. A brush cleaner824and a contact roller826are located at one end834of the media path P. A heater830and a spreader832are located at the opposite end836of the media path P.

Operation and control of the various subsystems, components and functions of printing system800are performed with the aid of a controller828and memory829. In particular, controller828monitors the velocity and tension of the media web814and determines timing of ink drop ejection from the print modules880-899. The controller828can be implemented with general or specialized programmable processors that execute programmed instructions. Controller828is operatively connected to memory829to enable the controller828to read instructions and to read and write data required to perform the programmed functions in memory829. Memory829can also hold one or more values that identify tension levels for operating the printing system with at least one type of print medium used for the media web814. 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.

As illustrated inFIG. 10, the media web814passes various heating elements such as, for example, the heated plate819and the heater830, each of which applies heat to the media web to facilitate subsequent processing. Other embodiments of continuous web printers may include other heating elements positioned in varying locations along the media path P. At each location along the continuous web printer system800where a heating element applies heat to the media web814, a risk exists that the media web can be weakened by the heat and break. One previous attempt to prevent printer heating elements from degrading media includes placing a metal screen between the heating element and the media. The screen absorbs heat, however, and if the media contacts the metal screen, the screen can overheat the media. Accordingly, in printers that include heating elements positioned along a media path, reliably preventing the heating element from degrading the media web814is a desirable goal.

SUMMARY

A printer having an active media shielding device has been developed to prevent printer heating elements from degrading print media. The printer includes a media transport configured to move media along a path through the printer in a process direction. The printer also includes a heater positioned along the path of the media through the printer to heat the media as the media moves by the heater. The printer further includes an endless belt interposed between the heater and the media moving along the path, and an actuator operatively connected to the endless belt to rotate the endless belt and dissipate heat in the endless belt.

An apparatus for mounting within a printer has been developed to prevent printer heating elements from degrading print media. The apparatus includes a heater positioned along a path of the media through the printer to heat the media as the media moves by the heater. The apparatus also includes an endless belt of mesh entrained about a first pulley and a second pulley. The endless belt of mesh is configured to be interposed between a heater and a media path in the printer. The apparatus further includes an actuator operatively connected to the first pulley to rotate the endless belt and dissipate heat absorbed by the endless belt from the heater before a portion of the endless belt moves parallel to a process direction along the media path.

DETAILED DESCRIPTION

The description below and the accompanying figures provide a general understanding of the environment for the printer having a heating system and an active media shielding device disclosed herein as well as the details for the device and assembly. In the drawings, like reference numerals are used throughout to designate like elements.

FIG. 1is a front perspective view of a heater system100for use within a printer, such as printer800shown inFIG. 10. The heater system100includes a support structure104, a pneumatic system108, and a pair of heater panels112operatively coupled to the pneumatic system108. The pneumatic system108and the heater panels112are configured with the support structure104so actuation of the pneumatic system108moves the heater panels112from an idle position (shown inFIG. 1) to an in-use position (shown inFIG. 2). The support structure104can be made of, for example, sheet metal, or another durable material having high heat tolerance. Thermal barriers116are mounted along the sides of the support structure104, pneumatic system108, and radiant heater panels112to prevent heat generated by the heater panels112from damaging other systems within the printer. By way of example, only one barrier116mounted on one side is shown here. Additionally, an active device124for shielding media from the radiant heater panels is provided between the heater100and a media path.

The heater system100shown inFIG. 1is a radiant heater subsystem configured to generate thermal energy sufficient to heat print media120(shown inFIG. 2) prior to the print media entering a spreader (such as spreader832shown inFIG. 10), which spreads and fixes ink to the print media120. More specifically, in this embodiment, the heater panels112are long-wave infrared heater panels operated to have surface temperatures of, for example, 300 to 400 degrees Celsius. The reader should understand, however, that the active device is applicable to different types of heater systems and different temperature ranges.

As shown inFIG. 2, when the heater panels112are positioned parallel to the print media120, the media is exposed to a maximum amount of heat. In this embodiment, the print media120is a continuous web of print media driven in a process direction PD. The active devices described in this document, however, is also applicable in heaters that heat media not in the form of a continuous web. As the print media120passes the radiant heater panels112, the print media120and the radiant heater panels112are separated by a distance D1of, for example, less than 1 inch. If the movement of the print media120is suspended in front of the heater panels112for a longer period of time than is required for effective spreading of the ink with the spreader, the print media120may be degraded and break. To address this issue, the active media shielding device124is configured to attenuate the exposure of the print media120to the heater panels112for such extended periods of time. As shown inFIG. 2, the shielding device124includes an endless belt128and a cleaning device132.

More specifically, as shown inFIG. 3, the endless belt128is interposed between the print media120and the heater panels112and is arranged so as to be substantially parallel with the print media120and the heater panels112when the heater panels112are parallel to the media as shown inFIG. 2. The endless belt128is preferably made of a mesh to provide surface area on the endless belt128and thereby enable the endless belt128to be cooled by ambient air. The mesh is made of a heat tolerant material such that it can withstand the radiant heat generated by the heater panels112. Further, the mesh is made of a heat resistant material such that the temperature of the endless belt128remains less than that of the heater panels112. In at least one embodiment, the mesh is substantially made of, for example, at least one of stainless steel, fiberglass, and a thermally insulating material, such as INCONEL®. The mesh of the endless belt128is configured with a diameter and frequency of strands of the material sufficiently small such that energy emitted by the heater panels112is not significantly altered prior to reaching the print media120.

The endless belt128is suspended on a driven pulley140and an idler pulley144such that the endless belt128is tensioned by the driven pulley140and idler pulley144. The pulley140is rotationally driven by the actuator136such that when the actuator136rotates the driven pulley140, the endless belt128rotates around the driven pulley140and the idler pulley144. Rotating the driven pulley140with the actuator136rotates the endless belt128and the idler pulley144. The actuator136rotationally drives the driven pulley140at a speed sufficiently fast such that any portions of the print media120that contact the endless belt128are carried out of the area in front of the heater panels112prior to the media being degraded. For example, the actuator136can drive the driven pulley140at a speed of approximately 180 mm/s or faster.

The driven pulley140and the idler pulley144each have a diameter DIAM such that the when the endless belt128is positioned on the pulleys140,144, portion148of the endless belt128is closer to the heater panels112than portion152of the endless belt128, which is positioned closer to the print media120. The separation of portion148and portion152by the diameter DIAM of the pulleys140,144enables ambient air to pass through the belt and dissipate heat from the endless belt128. The driven pulley140is operated by the actuator136to rotate in a direction shown by arrow A such that portion148travels between the pulleys140,144in a direction opposite to the process direction PD and portion152of the endless belt128travels between the pulleys140,144in the process direction PD. This arrangement is advantageous because if any portion of the print media120comes into contact with portion152of the endless belt128, the print media120and the media portion152are traveling in the same direction. This common direction of movement prevents the print media120from becoming stuck or tangled in the endless belt128while being exposed to the panels112.

The cleaning device132is positioned to contact the endless belt128without being interposed between the heater panels112and the print media120. In the embodiment shown inFIG. 3, the cleaning device132is arranged above the endless belt128, adjacent to the heater system100, and above the idler pulley144. More specifically, the endless belt128has a length LB which is longer than a length LH of the heater system100. This length difference provides a space156in which to arrange the cleaning device132to enable the cleaning device132to contact the endless belt128without being interposed between the heater panels112and the print media120. The length LB of the endless belt128can be, for example, 450 mm, and the length LH of the heater system100can be, for example 350 mm, such that the space156for the cleaning device132is approximately 100 mm. While this arrangement is an example of one advantageous embodiment, other arrangements and locations for the cleaning device132can be used to achieve these goals.

The cleaning device132is further arranged so as to contact the endless belt128after the endless belt128passes nearest to the print media120and before the endless belt128passes by the heater panels112. In other words, the cleaning device132is arranged between portion152and portion148of the endless belt128. This positioning enables the cleaning device132to clean any portions or particles of the print media120from the endless belt128before such media debris is brought into the vicinity of the heater panels112.

In at least one embodiment, the cleaning device132includes a vacuum source and stiff bristles134. The stiff bristles134are located such that the endless belt128contacts the stiff bristles as a vacuum is applied to an opening in the cleaning device132in which the bristles134are mounted. Accordingly, any media debris on the endless belt128is loosened from the endless belt128by the stiff bristles and vacuumed from the endless belt128by the vacuum source before that portion of the endless belt128passes by the heater panels112.

FIG. 4depicts another type of printer280in which an active media shielding device224(shown inFIG. 5), substantially similar to the active media shielding device124, can be used. As shown inFIG. 4, a continuous web of print media220is unwound from a first roll of unprinted media284, passes through the printer280, and is wound onto a second roll of printed media288.FIG. 5depicts a schematic view of a heater system200positioned within the printer208shown inFIG. 4. The heater system200is a dryer used for drying printed images on print media220using a plurality of infrared lamps260, a back reflector264, and a dryer enclosure268. The dryer200includes six infrared lamps260, each of which is, for example, a twin tube, carbon arc emitting lamp having a medium wavelength of approximately 2 micrometers, emitting 4000 watts, and having a surface temperature that reaches 1500 to 2000 degrees Celsius. Each infrared lamp260has a respective slot dryer plenum272coupled thereto. A media shielding device224is interposed between the infrared lamps260and the print media220.

FIG. 6depicts a larger view of two of the infrared lamps260and a portion of the media shielding device224in more detail. The shielding device224is substantially similar to, but is smaller than, the shielding device124described above with reference toFIGS. 1-4because the distance D2between the infrared lamps260and the print media220is approximately 35 mm. Each of the driven pulley240(shown inFIG. 5) and the idler pulley244therefore, has a diameter DIAM which is smaller than 35 mm. Accordingly, the endless belt248is arranged within the distance D2between the infrared lamps260and the print media220to prevent the print media220from being degraded by the heat produced by the dryer200.

Returning toFIG. 5, each infrared lamp260produces heat directed toward a front side of the print media220as the print media passes through the dryer200. The heat is reflected onto a back side of the print media220by the back reflector264. The infrared lamps260and the back reflector264are enclosed within the dryer enclosure268which maintains the hot air temperature within the dryer200and circulates the hot air around the print media220. The media shielding device224is interposed between the infrared lamps260and the print media220.

In an alternative embodiment shown inFIG. 7, each of the infrared lamps260′ has a respective, individual media shielding device224′ interposed between the infrared lamp260′ and the print media220′. Accordingly, in this alternative embodiment, the dryer200′ includes six infrared lamps260′ and six respective media shielding devices224′. One of the infrared lamps260′ and respective media shielding devices224′ is depicted inFIG. 8in more detail. As shown, the diameter DIAM′ of each of the driven pulley240′ and idler pulley244′ is smaller than the distance D2′ between the infrared lamp260′ and the print media220′ to enable the endless belt248′ to be arranged between the infrared lamp260′ and the print media220′ and thereby prevent the print media220′ from being degraded by the heat produced by the dryer200′.

The embodiments of the media shielding devices124,224, and224′ have been shown as being mounted within a printer. Additionally, support members704can be provided, as shown inFIG. 9, to enable an actuator736, rollers or pulleys740,744, and a cleaning device732of a media shielding device724to be mounted to the support members704and form a modular apparatus700. This apparatus700can be retrofitted in existing printers to interpose the endless belt728of the media shielding apparatus724between a heater in the printer and a media path within the printer.

It will be appreciated that some or all of the above-disclosed features and other features and functions or alternatives thereof, may be desirably combined into many other different systems, apparatus, devices, or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.