EP0435516A2 - Gerät und Verfahren zum Trocknen und Schmelzfixieren für eine elektrofotografische Hochgeschwindigkeitsdruckvorrichtung - Google Patents

Gerät und Verfahren zum Trocknen und Schmelzfixieren für eine elektrofotografische Hochgeschwindigkeitsdruckvorrichtung Download PDF

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Publication number
EP0435516A2
EP0435516A2 EP90313581A EP90313581A EP0435516A2 EP 0435516 A2 EP0435516 A2 EP 0435516A2 EP 90313581 A EP90313581 A EP 90313581A EP 90313581 A EP90313581 A EP 90313581A EP 0435516 A2 EP0435516 A2 EP 0435516A2
Authority
EP
European Patent Office
Prior art keywords
air
dryer
recited
web
catalytic converter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90313581A
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English (en)
French (fr)
Other versions
EP0435516A3 (en
Inventor
Mark F. Duchesne
Richard A. Gaspar
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AB Dick Co
Original Assignee
Multigraphics Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Multigraphics Inc filed Critical Multigraphics Inc
Publication of EP0435516A2 publication Critical patent/EP0435516A2/de
Publication of EP0435516A3 publication Critical patent/EP0435516A3/en
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/11—Removing excess liquid developer, e.g. by heat
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00443—Copy medium
    • G03G2215/00451—Paper
    • G03G2215/00455—Continuous web, i.e. roll
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/20—Details of the fixing device or porcess
    • G03G2215/207—Type of toner image to be fixed 
    • G03G2215/2083—Type of toner image to be fixed  duplex

Definitions

  • the present invention pertains to a high speed electrophotographic printing press and specifically to a dryer-fuser apparatus therefor which is utilized to evaporate toner carrier liquid from and fuse color-imparting toner solids particles to a travelling web or the like after the desired image has been transferred from an electrophotographic printing cylinder to the web.
  • Electrophotographic printing is well known and has been widely refined. For example, today, almost every office and indeed some homes have electrophotographic copiers. The industry has grown to the point where it is now a highly competitive multi-billion dollar industry. In most instances, these home and office copiers are capable of providing only about a few copies per minute.
  • images are photoelectrically formed on a photoconductive layer mounted on a conductive base.
  • Liquid or dry developer or toner mixtures may be used to develop the requisite image.
  • Liquid toner dispersions for use in the process are formed by dispersing dyes or pigments and natural or synthetic resin materials in a low dielectric constant carrier liquid.
  • Charge control agents are added to the liquid toner dispersions to aid in charging the pigment and dye particles to the requisite polarity for proper image formation on the desired substrate.
  • the photoconductive layer is sensitized by electrical charging whereby electrical charges are uniformly distributed over the surface.
  • the photoconductive layer is then exposed by projecting or alternatively by writing over the surface with a laser, L.E.D., or the like.
  • the electrical charges on the photoconductive layer are conducted away from the areas exposed to light with an electrostatic charge remaining in the image area.
  • the charged pigment and/or dye particles from the liquid toner dispersion contact and adhere to the image areas of the photoconductive layer.
  • the image is then transferred to the desired substrate, such as a travelling web of paper or the like.
  • high speed electrophotographic printing presses In contrast to office and home copiers, high speed electrophotographic printing presses are being developed wherein successive images are rapidly formed on the photoconductive medium for rapid transfer to carrier sheets or the like travelling at speeds of greater than 100 ft./min. and even at speeds of from 300-500 ft./min. These high speed presses are capable of delivering 10 million copies per month with web or copy widths being on the order of 20 inches or greater.
  • a dryer-fuser apparatus and method are provided for utilization in a high speed electrophotographic printing process of the type adapted to operate at web speeds of 100 ft./min. and greater. More specifically, such high speed methods may operate at speeds of 300-500 ft./min.
  • the travelling web is forwarded by conveyor rolls or the like into a dryer housing that is provided with a pair of opposed hot air supply manifolds.
  • Each manifold communicates with a plurality of air supply tubes that extend transversely across the web travel direction.
  • the tubes are each provided with a plurality of apertures through which hot air passes to effect drying of the web.
  • the velocity of the hot air emanating from the tubes provides an air cushion for the web's travel through the dryer so that substantially no or little contact of the web is made with the air supply tubes during web travel through the dryer. As such, the web is suspended in the air cushion. Volatiles and hot air from the dryer housing are vented to a conduit in communication with a catalytic converter device.
  • such catalytic converter devices comprise a fixed bed catalyst that supports exothermic degradation of the volatile organic compounds.
  • the hot effluent gases emanating from the catalytic converter may then be either vented to exhaust or a portion thereof may be recycled to the air supply manifolds to provide heat for the drying process.
  • the use of recycled heat from the catalytic oxidation of carrier liquid to dry and fix an image transferred to a copy sheet is not, in and of itself, new.
  • U.S. Patent 4,538,899 discloses such methods and a device therefor.
  • a portion of the recycled heat from the catalytic converter is returned to an upstream heat exchanger to heat the volatile materials and hot air vented from the dryer housing.
  • the volatiles and hot exhaust air emanating from the dryer housing may be preheated prior to their passage through the catalytic converter.
  • an electrical resistance heater or the like may be used to supply heat to the dryer.
  • a recycle bypass damper is also provided to regulate the amount of recycled heat from the catalytic converter that is recycled to the dryer.
  • a make-up air damper in communication with a source of fresh make-up air, regulates the amount of fresh make-up air that is forwarded to the heater.
  • the amount of make-up air admitted to the dryer is controlled by a pressure monitoring device that measures the pressure within the dryer.
  • An active flame sensor monitors the lower flammability level of the atmosphere within the dryer.
  • the speed of the dryer exhaust fan is controlled so that the atmosphere is preferably maintained at or below about 25% of the lower flammability level (L.F.L.) for the particular carrier liquid that is used.
  • L.F.L. lower flammability level
  • FIG. 1 shows the overall organization of a typical photoconductive cylinder and associated mechanisms for formation of the latent electrostatic image, and subsequent image formation on the cylinder surface.
  • a rotatable photoconductive drum 50 typically As2Se3, SeTe or others, rotates in a counterclockwise direction as indicated by the arrow shown on cylinder 50 in Fig. 1.
  • Special systems are arranged sequentially around drum 50 as shown in Fig. 1, to accomplish the desired formation and transfer of images onto web w. These systems include a high intensity charging apparatus 52, exposing-discharging (or imaging) apparatus 54, developing apparatus 55, transfer apparatus 56 and cleaning apparatus 58. These assure that the drum surface is charged, exposed, discharged and cleared of residual toner, while the developed images are continually transferred to the web material w.
  • Charging apparatus 52 comprises a plurality of corona discharge devices comprising corona discharge wires disposed within appropriately shaped shielded members with each wire and associated shield member forming a separate focusing chamber.
  • the charge imparted by the coronas to the photoconductive cylinder is on the order of at least +1000 volts d.c., preferably between +1000 and +1450 volts.
  • These corona assemblies extend across the drum surface 51 and along an arc closely parallel to surface 51.
  • the arcuate length of the charging unit is about 4.5 inches or somewhat greater than 1/8th of the drum circumference.
  • a charge potential sensor 65 (an electrometer) which senses the voltage at the surface 51 and provides a continuous feedback signal to a charging power supply (not shown) to thereby adjust the charge level of the photoconductor surface 51 regardless of variations due, for example, to irregularities in the power supply or changes in the peripheral velocity of drum 50.
  • Digital imaging device 54 in the form of relatively high intensity L.E.D. double row array 70 is mounted to extend transversely of the rotating drum surface 51.
  • Each L.E.D. is individually driven from a corresponding driver amplified circuit, details of which need not be described herein.
  • Light emitted from the L.E.D.s is in the range of 655-685 nm through a Selfoc lens 72 onto the drum surface 51 in a dot size of 0.0033 inch diameter.
  • there are a total of 6144 L.E.D.s in the array divided between two rows which are spaced apart in a direction along the circumference of the surface by 0.010 inch and all fixed to a liquid cooled base block (not shown).
  • the space between adjacent L.E.D.s in the same row is 0.0033 inch horizontally or transverse to the drum surface and the L.E.D. arrays in the two rows are offset horizontally by the same dimension, thus the L.E.D.s can cooperate to discharge a continuous series of dots across drum surface 51 at a resolution of 300 dots/inch.
  • Light from the L.E.D.s operates to discharge the background or non-image areas of the passing drum surface to a substantially lower potential, for example, in the order of +100 to +300 volts d.c. by exposing individual dot areas to radiation at a predetermined frequency, as mentioned, whereby the remaining or image areas comprise a latent electrostatic image of the printed portions of the form.
  • L.E.D. arrangement has been depicted herein as providing for the requisite image, other conventional means for forming the requisite image may also be utilized. For instance, laser printing and conventional exposure methods such as reflection from high contrast originals and projection through transparencies and the like may also be utilized, although they are not preferred.
  • drum 50 comprises an As2Se3 photoconductive layer to which charge coronas 52 impart a positive charge.
  • the toner particles are accordingly provided with a negative charge in the range of about 60 to 75 picamhos/cm.
  • the developing station 55 comprises a shoe member 80, which also functions as a developer electrode (which is electrically insulated from drum 50 and extends transversely across drum surface 51).
  • the face of shoe member 80 is curved to conform to a section of drum surface 51 and, in a successful embodiment, has a length, along the arcuate face, of about 7 inches, slightly less than 1/4 of the circumference of drum surface 51, and which is closely fitted to the moving drum surface, for example, at a spacing of about 500 microns (0.020 inch).
  • Shoe 80 is divided into first and second cavities 82, 83 (see Fig. 5) through each of which is circulated liquid toner dispersion from a liquid toner dispersion supply and replenishment system.
  • Liquid toner dispersion is supplied to developer electrode 80 through conduit 10 via action of pump 12 and associated adjustable flow valve 14.
  • the toner dispersion is fed to manifold 16 and then through inlet supply pipes 18(a-d).
  • Polyurethane tires 20, 22 are journalled in the sidewalls of developer electrode housing and ride upon anodized rims that are circumferentially disposed about periphery of drum 50.
  • a direct current source, indicated generally by the reference numeral 24, is provided to apply bias through conductor 26 to the electrode 80.
  • a toner sump 28 is provided to surround electrode 80 and is provided with a sump return line 30 to return spent toner dispersion to a liquid toner supply system (not shown).
  • the developer shoe 80 functions as an electrode which is maintained at a potential on the order of about +200 to 600 volts d.c.
  • the negatively charged toner particles are introduced into the shoe cavities and are dispersed among electrical fields between: 1) the image areas and the developer electrode on the one hand and between 2) the background and the developer electrode on the other hand.
  • the electrical fields are the result of difference in potential: a) between the images areas (+1000 to 1450 volts) and the developer electrode (+200 to +600 volts) which causes the negatively charged toner particles to deposit on the image areas, and b) the field existing between the background areas (+100 to +300 volts) and the developer electrode (+200 to +600 volts) which later field causes the toner particles to migrate away from the background areas to the developer shoe.
  • the result is a highly distinctive contrast between image and background areas, with good color coverage being provided in the solid image areas.
  • the tendency of toner particles to build up on the developer shoe or electrode is overcome by the circulation of the liquid toner therethrough at rates on the order of about 7.57 to 37.85 liters/min. (2 to 10 gallon/min.) back to the toner refreshing system.
  • a reverse rotating metering roll 32 spaced parallel to the drum surface by about .002-.003 in., acts to shear away any loosely attracted toner in the image areas, and also to reduce the amount of volatile carrier liquid carried by the drum and any loose toner particles which might have migrated into the background areas.
  • the metering role has applied to it a bias potential on the order of about +200 to +600 volts d.c. from d.c. power source 34 and conductor 36, varied according to web velocity.
  • Reverse roll 32 is driven via drive roller 38 with drive being transmitted through belt or chain member 40.
  • a position sensor 42 is provided to sense the position of roll 32 as shall be explained in greater detail hereinafter.
  • a transfer apparatus 56 adapted to effect transfer of the image from the photoconductive surface to a travelling web w of paper or the like.
  • a pair of idler rollers 90a, b guide web onto the "3 o'clock" position of drum 50 and behind the web path at this location is a transfer coratron 92.
  • the web is driven at a speed equal to the velocity of drum surface 51 to minimize distortion of the developed image on the surface 51.
  • the positioning of rollers 90a, b is such that the width (top to bottom) of the transverse band 95 of web-drum surface contact is about 0.5 inch centered on the radius of the drum which intersects the coratron 92.
  • the shape of the transfer coratron shield 96, and the location of the axis of the tungsten wire and shield 96 is such as to focus the ion "spray" from the coratron onto the web-drum contact band on the reverse side of web w.
  • the transfer coratron 92 has applied to it a voltage in the range of +6600 to +8000 volts d.c., and the distance between the coratron wire 93 and the surface of web w is in the order of about 0.25-0.35 inch - preferably .317 inch. This results in a transfer efficiency of at least 95% of the solids particles of the liquid toner dispersion. Both solid toner particles and liquid carrier material are transferred to the web.
  • a cleaning apparatus 58 is utilized to remove all toner particles and carrier liquid from the drum surface 51 and erase lamp lll is arranged to flood surface 51 with either blue or white light emanating from a fluorescent tube. Satisfactory cleaning results have been achieved with blue fluorescent tubes emitting predominantly at about 440 nm and with white fluorescent tubes emitting predominantly at 400, 440, 550 and 575 nm.
  • the foam roller 60 is of a polyurethane open cell construction and is fixed to a power driven shaft which is rotated in the opposite direction to drum surface motion, as indicated by the arrows in Fig. 1, so as to compress against and scrub the surface 51.
  • the compression/expansion of the open cell foam during this action will tend to draw liquid carrier material and any included toner particles remaining on the surface 51 off of that surface and into the cells of roller 60.
  • a cleaning blade 66 comprising a tough, but flexible, polyurethane wiper blade is mounted with its edge extending forward and into contact with surface 51, just beyond foam roller 60. Blade 66 acts to wipe the drum surface 51 dry, since the photoconductor surface must be dry when it reaches the charging station.
  • Fig. 2 it can be seen that web, w, is admitted into dryer-fuser apparatus 100, comprising housing member 112.
  • the web is conveyed through the dryer-fuser by use of roller 90b and drive roller 102.
  • the web is guided downwardly along an inclined path through the dryer-fuser.
  • the dryer is designed to fuse toner on both sides of the web. In perfecting printing both sides of the web become "wet".
  • Roller 90b has a surface made of expanded metal which presents a multitude of sharp points to support the web.
  • the toned image only touches the this roll at discrete points each of minuscule size (or area) so the image is not disrupted. This is important in minimizing disturbance or distortion of the desired image.
  • Air supply manifolds 104, 106 are provided with each carrying air supply tubes 108, 110 which tubes extend transversely across the surfaces of the web with the lower and upper array of tubes being offset from the other. As can be seen, the web is interposed between the surfaces of the tubes 108, 110 which are provided with a multiplicity of apertures therein to blow hot air onto the web from opposite sides thereof.
  • the flow rate of hot air emanating from the air supply tubes 108, 110 is such as to provide an air cushion to cushion the web as it travels through the heater.
  • the web essentially floats through the heater while making little or no contact with surface portions thereof. Again, this tends to minimize smearing and image distortion that may otherwise occur during heating processes wherein the travelling web is contacted with roller and/or heater surfaces in the heater proper.
  • Heated air at a temperature on the order of around 250°F is ejected at 5,000 to 10,000 fpm from the air supply tubes as the surfaces of the moving web are transported at velocities in the range of from 100-500 ft./min.
  • the hot air velocity is such that the web is kept spaced away from the nozzle arrays and follows a somewhat sinuous path between the manifolds 104, 106.
  • the hot air performs two functions. First, it volatilizes the liquid carrier material that has been applied to the travelling web. Secondly, it heats the web causing the solids toner particles to fuse onto the desired place on the web. In a typical operation, this requires sufficient heat transfer to remove and vaporize carrier liquid at rates of about 850g/min. and higher. Volatiles and hot air in housing 112 are vented through conduit 114 and filter 116 by the action of downstream exhaust fan 118 thereon. The vented volatiles-hot exhaust air pass along conduit 114 to heat exchanger 120, the function of which shall be explained hereinafter.
  • an electrical resistance heater 122 is operated to provide supplementary heat through the conduits to supply manifolds 104, 106 through respective damper members 152, 154. Proceeding further in a downstream direction, the volatiles and hot air enter catalytic converter 124 wherein, in conventional manner, the volatile organic materials are exothermically converted into carbon dioxide and water whereby hot effluent exhaust air from catalytic converter 124 is passed to recycle line 126.
  • a portion of the hot effluent air from the catalytic converter is diverted into bypass conduit 128 and heat exchanger flow line 130 whereby it heats the vented volatiles-hot air in conduit 114 to preheat the volatiles and exhaust air from dryer 112 prior to admission thereof into the catalytic converter means 124.
  • the portion of heated effluent from catalytic converter 124 channeled through the heat exchanger is then conducted to exhaust port 132.
  • a damper means or the like, 134 is provided in the bypass conduit line 128 so as to regulate back pressure in the system and to aid in regulating the amount of hot effluent air from the catalytic converter 124 that is passed through heat exchanger 120.
  • a portion of the hot effluent air from catalytic converter 124 is conducted through recirculator conduit 126 and is returned via the action of supply fan 150 and conduit 148 through either damper 152 or 154 to supply hot air to the air manifolds 104, 106.
  • This is an important part of the invention in that, after the initial heat required for the process is provided by resistance heater 122, the resistance heater 122 can be turned off with heat supplied to the dryer 100 being composed entirely of heat emanating from catalytic converter 124 through recycle conduit lines 126 and 148.
  • a return line damper 136 is used to regulate the amount of this recycled heat that is supplied to the manifolds 104, 106.
  • a fresh make-up air source 138 is provided in conjunction with damper means 140 to regulate the amount of fresh make-up air drawn by supply fan 150 through conduit 148 through either damper 152, 154 to the manifolds 104, 106. If desired, direct exhaust from housing 112 may be drawn through filter 142 and conduit 144 to and through conduit 148 to recycle exhaust air (including volatiles) to the air manifolds 104, 106. The amount of recycled exhaust air is regulated by means of a damper 146.
  • the fuser-dryer apparatus thus is a recuperative system which effectively controls emissions from vaporization of the carrier liquid and recovers the resulting heat to further the fusing and drying process.
  • the roller 102 is chilled by internal cooling means and serves to reduce the temperature of the web material to approximately ambient. Downstream from this chilled drive roll 102, a plurality of other operations such as punching, perforating, rewinding, folding, sheeting, etc., may be performed on the travelling web in accordance with well-known techniques. Details of such additional operations may be gleaned from U.S. Patent 4,177,730, the content of which is herein incorporated by reference.
  • typical operating parameters of the dryer-fuser system of the invention include a temperature on the web surface of about 250°F during travel thereof through the dryer-fuser apparatus 100.
  • the temperature of the heat/exchanger output is about 500°F.
  • the dryer-fuser is adapted to operate at a level of 25% of the LFL (lower flammability level) of the carrier liquid or lower.
  • Variables important in maintaining such atmosphere are the minimum flammable vapor concentration of Isopar in air, web speed, solvent content of the traveling web, amount of fresh make-up air admitted to the system and the amount of return volatiles and hot air recycled to the heater through line 144 and damper 146.
  • a hot air dryer as described and claimed herein over other dryers, such as microwave dryers, is that a variety of different toners may be dried. For instance, certain microwave dryers rely upon energy at a particular wavelength. However, in the present invention, the travelling web is heated with heat transfer from the web to the toner being used to fuse the toner particles.
  • FIG. 3 there is shown, in block format, a simplified control system schematic for the apparatus.
  • a pressure monitoring device 202 such as a diaphragm containing pressure switch is contained within the dryer-fuser apparatus 100. Desirably, the pressure in the apparatus 100 is maintained at -1" H2O.
  • the information from the pressure monitor 202 is forwarded to a programmable logic controller (PLC) 250 that compares the measured pressure with a desired set-point pressure which, in this instance, is -1" H2O.
  • PLC programmable logic controller
  • the PLC sends an analog signal to adjustably open the make-up air damper 140 to in turn allow fresh make-up air to be supplied to the damper members 152, 154. Conversely, if the pressure exceeds the desired set point, the damper 140 is closed.
  • the opening or closing of hot air return damper 136 is similarly controlled by the PLC 250.
  • the temperature of the web exiting the dryer-fuser is measured by a thermocouple 204 or the like. This temperature information is supplied to the PLC 250 wherein it is compared to a predetermined set-point, here, for example 220°F. If the indicated temperature is greater than this desired set-point, the PLC sends an analog signal to the adjustable air return damper 136 to close same to prevent air from the catalytic converter from entering the conduit 148 for recycled use in the fuser-dryer. In contrast, if the web temperature is below the predetermined set-point, the damper 136 is opened to allow recycling of the air emanating from the catalytic converter 124.
  • thermocouple 206 measures the temperature with the fuser-dryer 100. This temperature information is supplied to PLC wherein it is compared to a predetermined set-point, for example, 350°F. Again, if the measured temperature exceeds this set point, the damper 136 is closed preventing communication between duct sections 126, and 148. If the measured temperature is below the set-point, the damper 136 is opened.
  • Temperature control of the hot-side bypass damper 134 is also provided.
  • a thermocouple or like device 208 is located just upstream from the catalytic converter 124. This temperature information is conveyed to the PLC where it is compared to a predetermined set-point range. Here, for example, if the measured temperature is less than about 450°F, the PLC transmits an analog signal to the damper controller to close the bypass damper 134 to ensure that all hot air travelling through duct 128 is diverted through heat exchanger flow line 130.
  • thermocouple 208 if the temperature information sent to PLC by thermocouple 208 exceeds the high end of the set-point range, for example, 550°F, the bypass damper 134 is opened, thereby ensuring that a portion of the air passing through duct line 128 will pass directly through the damper 134 to exhaust 132 without travel through heat exchanger flow line 130.
  • a control system is provided to monitor and regulate the percent of carrier liquid concentration in the dryer-fuser atmosphere.
  • a lower flammability limit (LFL) monitor 210 is positioned within the housing of the dryer-fuser.
  • the preferred monitor 210 is the Model FFA "Sensing Flame Detection System" available from Control Instruments Corporation, Fairfield, New Jersey. This device comprises an active sensing flame. Flammable vapors that enter the device are incinerated by the flame. This action results in an increase in the BTU output of the flame which is measured by a resistance temperature detector which is then transmitted and indicated on a control module in terms of the LFL.
  • This LFL signal is then used as input to the PLC 250.
  • the PLC sends an analog signal to a controller 212 which regulates (increases) the speed of the variable speed exhaust fan 118. If the LFL value exceeds an intermediate range set-point, for example, 25%, the PLC disconnects drive 214 for the chilled roll 102, thus stopping web travel through the dryer-fuser.
  • An upper range LFL set-point for example, 40% or 50%, may be set whereby in addition to actuation of the exhaust fan 118 and disconnection of drive for chill roll 102, audible alarm 216 is signal led.
  • sensor 42 monitors the position of reverse roller 32.
  • the reverse roller is not in its operative condition spaced closely adjacent to surface 51 so as to shear excess toner carrier liquid and solids particles from the surface, a signal is sent to PLC 250 (Fig. 3) to disconnect drive 214 for the chilled roll 102 to halt advancement of the web through the dryer.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Wet Developing In Electrophotography (AREA)
EP19900313581 1989-12-28 1990-12-13 Dryer-fuser apparatus and method for high speed electrophotographic printing device Withdrawn EP0435516A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US45731789A 1989-12-28 1989-12-28
US457317 1995-06-01

Publications (2)

Publication Number Publication Date
EP0435516A2 true EP0435516A2 (de) 1991-07-03
EP0435516A3 EP0435516A3 (en) 1992-04-01

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Application Number Title Priority Date Filing Date
EP19900313581 Withdrawn EP0435516A3 (en) 1989-12-28 1990-12-13 Dryer-fuser apparatus and method for high speed electrophotographic printing device

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0867786A1 (de) * 1997-03-14 1998-09-30 Agfa-Gevaert N.V. Schmelzfixierung von zweiseitigen mehrschichtigen Kopien in einem einzigen Umlauf
US5983063A (en) * 1997-03-14 1999-11-09 Agfa-Gevaert N.V. Single-pass fusing of multi-layer duplex copies
WO1999057611A1 (en) * 1998-05-06 1999-11-11 Imation Corp. Drying system and method for an electrophotographic imaging system
EP2081088A1 (de) * 2008-01-18 2009-07-22 Miyakoshi Printing Machinery Co., Ltd. Tonerfixiervorrichtung und elektrophotografischer Drucker

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3934112A (en) * 1974-03-04 1976-01-20 Honeywell Information Systems, Inc. Drying and fixing techniques for electrographic printing system
US4538899A (en) * 1983-02-22 1985-09-03 Savin Corporation Catalytic fixer-dryer for liquid developed electrophotocopiers
JPH0772811B2 (ja) * 1987-11-10 1995-08-02 株式会社日立製作所 両面記録装置

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0867786A1 (de) * 1997-03-14 1998-09-30 Agfa-Gevaert N.V. Schmelzfixierung von zweiseitigen mehrschichtigen Kopien in einem einzigen Umlauf
US5983063A (en) * 1997-03-14 1999-11-09 Agfa-Gevaert N.V. Single-pass fusing of multi-layer duplex copies
US6002894A (en) * 1997-03-14 1999-12-14 Agfa-Gevaert Single-pass fusing of sheet-fed multi-layer duplex copies
WO1999057611A1 (en) * 1998-05-06 1999-11-11 Imation Corp. Drying system and method for an electrophotographic imaging system
EP2081088A1 (de) * 2008-01-18 2009-07-22 Miyakoshi Printing Machinery Co., Ltd. Tonerfixiervorrichtung und elektrophotografischer Drucker
US8295754B2 (en) 2008-01-18 2012-10-23 Miyakoshi Printing Machinery Co., Ltd. Toner-fixer apparatus and electronic photograph printer

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CA2031775A1 (en) 1991-06-29

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