US3448970A - Fuser for electrostatic images - Google Patents

Fuser for electrostatic images Download PDF

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Publication number
US3448970A
US3448970A US663185A US3448970DA US3448970A US 3448970 A US3448970 A US 3448970A US 663185 A US663185 A US 663185A US 3448970D A US3448970D A US 3448970DA US 3448970 A US3448970 A US 3448970A
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United States
Prior art keywords
conveyor
sheet
heat
area
toner
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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.)
Expired - Lifetime
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US663185A
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English (en)
Inventor
James A Kolibas
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AB Dick Co
Original Assignee
Multigraphics Inc
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Publication date
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Publication of US3448970A publication Critical patent/US3448970A/en
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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
    • G03G15/20—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
    • G03G15/2007—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using radiant heat, e.g. infrared lamps, microwave heaters

Definitions

  • the electrostatic copy process generally employs a flexible carrier sheet upon which a toner material is caused to first adhere by electrostatic attraction, and thereafter by adhesion upon being fixed. Fixing is most usually a heat fusion.
  • the fusing is done under high intensity infra-red radiation conditions.
  • the heat absorbing characteristic of the dark color toner and phenomenon of mutual effect of heating, will cause the larger masses of the toner to create a temperature build-up at a greater speed than the small particle areas.
  • This invention is concerned with the provision of apparatus to convey a sheet through a focused infra-red heat source quickly, and avoid the consequences of the heat concentration upon the conveying apparatus.
  • Uniform heating is a requirement for proper fusing.
  • the speed of a sheet passing through the energy Zone, and the intensity of the energy can be balanced to cause the proper fusing of desired indicia toner masses, and lack of fusing of stray particles.
  • a nonuniform conveyor condition is introduced, then the balance with respect to one area will not be proper with respect to another. It is critical to provide heating uniformity in the heat focus zone.
  • a single conveyor belt is another possibility.
  • the belt may be composed into two separate conveyor units, or one unit may detour the heat area. Concentration of infra-red radiation creates good selective fusing conditions, whether or not focusing reflectors are used, but creates the danger of burning the belts, as well as the operational problem of uneven heating. If a single conveyor is employed, then the conveyor 3,448,970 Patented June 10, 1969 may deteriorate under the intense heat conditions, and also the surface of the conveyor may heat nonuniformly, thus causing the operating conditions under the reflector to vary. If the carrier sheet is warmed eXcessively it will cause the unwanted small particles to fuse more easily than if it is cold. If a solid conveyor surface is subject to a spotty heat retention condition, it is difficult to control the ambient temperature.
  • a heat sink is usually considered a body to absorb, or draw away, a large quantity of energy to protect a sensitive area.
  • This invention uses a heat sink, in its preferred embodiment, as a means to produce a uniform transport surface temperature in the heat area, and to keep the uniform temperature within acceptable limits.
  • any radiation will fall directly on the heat sink surface, thereby raising its temperature.
  • an imaged and toned sheet enters the fuser, it is at room temperature. It, therefore, exists at a lower temperature than does the heat sink surface. Because heat flows from higher to lower temperature, thermal energy transfer will be to the toned sheet rather than from it.
  • Uniform temperature of the surface requires good thermal conductivity. Because the heat sink surface rests directly in view of the heat source, and a great deal of radiant energy is concentrated upon it, it is desirable that the surface not heat excessively. The surface must, therefore, permit rapid heat loss to take place by re-radiation or by convection. Only by keeping the release rate of heat high, can the equilibrium temperature of the sink surface be kept to a reasonable range. This is a classic function of the heat sink.
  • the invention is concerned with providing a support surface portion of a conveyor system at a uniform equilibrium temperature.
  • the equilibrium temperature is balanced with the rate of carrier sheet travel over the surface, and the fusing temperature of the toner used.
  • the temperature of the support surface will usually be greater than the fusing temperature of the toner, but the carrier sheet will have a resistance to transmission of thermal energy, and the speed of travel will cause a given area to pass over the heat sink surface before the top surface of the carrier sheet comes to the temperature of the heat sink surface, or transmits enough heat to fuse the undesired particles.
  • the conveyor which may be a continuous conveyor diverted or a series of conveyors in contiguous relationship, will cause the conveyed sheet to slide across the inert area and be picked up by the moving conveyor on the opposite side of the heat zone.
  • the invention hereinafter described is understood to be an environment wherein it is attempted to selectively and preferentially fuse desirable areas of heat fusible toner.
  • a further advantage is found in that the sheet carrier itself is kept at a temperature below that which would destroy the useful and desirable characteristics of the sheet, whereas the color-bearing toner is caused to elevate in temperature by reason of absorption of radiant energy.
  • FIGURE 1 is a schematic illustration of a sheet conveyor system through a fusing station, and including prior process steps in block diagram;
  • FIGURE 2 is a section taken along the line 22 of FIGURE 1.
  • a toner material is applied to the sheet carrier, by a known process device indicated by a block in the drawing labeled toner.
  • the toner material is capable of being attracted to an electrostatic charge on the surface of the sheet carrier.
  • the toner is fusible upon exposure to radiant energy or ambient heat.
  • the toner is applied across the charged and exposed surface, and those areas not discharged by exposure will attract and hold some of the toner material.
  • the toner material is caused to fuse and hence bind to the sheet carrier. In this process a permanent image is perfected.
  • a drive roller 12 provides a common roller serving the belt conveyor 10, and an internal belt conveyor 14. A toned sheet delivered by the conveyor 10 will be transferred to the belt conveyor 14.
  • Conveyors 10 and 14 are preferably a plurality of individual narrow belts rather than one wide belt, although the preference is not a limiting requirement.
  • the belt conveyor 14 has an inert section in the form of heat sink 16.
  • the heat sink 16 is a bar of high thermal conductivity metal and extends across the path of conveyor 14. Bar 16 extends across the width of the conveyor, and in that sense it may be said to be as wide as the maximum size sheet to be transported n the conveyor 14, but is considerably more narrow than the length of the sheet to be transported. Then, by the provision of three rollers 18, 19 and 20, a detour for the belt-conveyor 14 is provided around the bar 16. If the bar 16 is not overly wide, a sheet delivered to the belt conveyor 14 will be pushed over the inert bar 16 to the opposite active portion of the belt 14 and hence is caused to move along the path of travel without hesitation. By use of one conveyor detoured, the conveyor to and from the heat sink is exactly synchronized in surface speed.
  • the heat sink body in the form of bar 16 preferably has a flat top support surface which lies in a common plane with the fore and aft sections of the belt conveyor 14, and is termed an inert portion of the conveyor in view of the fact that it does not move.
  • the bar 16 has a mass and a coefficient of thermal conductivity which conducts heat from the support surface at a rate greater than air conductivity to keep the support surface at an acceptable low temperature.
  • a radiant energy source 23 contains a lamp 25 for production of infra-red radiant energy.
  • Lamp 25 is a common item of commerce.
  • a reflector 27 surrounds the lamp 25 and causes a focus of the energy to a narrow band extending along the central area of the bar 16 support surface.
  • the support surface should be greater than the actual focus area in order to catch the direct radiation from the front of the lamp as well as the reflector focused energy.
  • the bulk of the energy output of lamp 25 is concentrated on a narrow band of the support surface.
  • the surface does heat the carrier sheet as it passes over the surface, but to a temperature which will permit reasonable sheet travel speed without destruction of the sheet or total fusing of a toner burden under the heat influence of the focused lamp.
  • a housing 31 covers the lamp area and is provided with an exhaust fan 33 to move air out of the housing 31. By moving the air out in this manner, air is of necessity drawn in, and the air which is drawn in is employed to complete the efficiency of this invention.
  • the housing 31 is attached to the machine housing 36, and the housing 36 is a restricted area over the top of the conveyor 10 and thus forms an entrance opening 37.
  • the housing has an exit opening 39 for discharge of finished sheets from the fusing process.
  • the radiant energy source 23 is preferably placed close to the entrance 37.
  • the opening 39 is a remote area with respect to both the source 23 and the exhaust fan 33, and air flow in through this opening will not flow to the source 23.
  • Air which enters through opening 39 will flow to the fan 33, but this movement merely assists in keeping the interior of the housing 31 at a low ambient temperature.
  • the air movement which enters directly into the fusing process is that air which is caused to act on a jet principle entering the entrance 37 and projecting between the reflector 27 and the conveyor 14. This air will keep the ambient temperature of the fusing area sufficiently low, that the action of the air and the heat sink together will prevent scorching of the carrier sheet, and permit a high concentration of radiant energy to act upon the dark heat absorbing toner on the surface of the carrier.
  • Apparatus for fusing toner material to a flexible carrier comprising:
  • a radiant energy source arranged to supply the energy output thereof onto a narrow area only
  • a belt conveyor having a path of travel aligned with the narrow .area and having a first portion approaching said area and stopping short thereof, means 'guiding said belt conveyor in a loop around said area, and a second portion receding from said narrow area beginning at a distance from the end of the first conveyor portion, said loop being at a greater distance from said radiant energy source than a straight line connecting said first and second portion;
  • the belt conveyor in operation transporting a carrier to, through and from the narrow area with the first and second conveyor portions supporting the carrier .5 during its travel and the carrier passing through said narrow area out of contact with said belt conveyor.
  • Apparatus for fusing toner materials to a flexible carrier comprising:
  • a heat sink body having a support surface, said body having a geometry and coeflicient of thermal conductivity correlated to conduct heat from said support surface at a rate greater than that obtainable by free convection cooling of thesurface area in T;
  • a radiant energy source arranged to Supply the energy output thereof to a narrow area of said support surface
  • a belt conveyor having a path of travel aligned with said support surface and having a first portion approaching said support surface and a second portion receding from said surface, means guiding said belt conveyor in a loop around said area, said loop being at a greater distance from said radiant energy source than a staright line connecting said first and second portions, the belt conveyor in operation transporting the carrier to, through and from the narrow area, with the first and second conveyor portion supporting the carrier and the carrier passing between conveyor portions supported only on the support surface of the heat sink body;
  • said heat sink is a bar extending transversely of said path of travel
  • said radiant energy source is focused along said bar.
  • Apparatus for fusing toner materials to a flexible carrier surface comprising:
  • a radiant energy source positioned to supply the energy output thereof to said support surface
  • belt conveyor means having a path of travel aligned with said support surface on two opposed sides thereof;
  • said support surface being the top surface of a heat sink bar extending transversely of said path of travel;
  • said radiant energy source positioned in saidireflector, said reflector and energy source con- 'structed to focus said energy along said bar support surface, said reflector spaced from said path;
  • a housing over said reflector area with an entrance and an exit opening for said belt conveyor; and exhaust means for evacuating said housing, said openings for said belt conveyor and said exhaust means coordinated to cause air drawn through at least one said opening to act as a nozzle directing air between said reflector and belt;

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fixing For Electrophotography (AREA)
US663185A 1967-08-04 1967-08-04 Fuser for electrostatic images Expired - Lifetime US3448970A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US66318567A 1967-08-04 1967-08-04

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US3448970A true US3448970A (en) 1969-06-10

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US663185A Expired - Lifetime US3448970A (en) 1967-08-04 1967-08-04 Fuser for electrostatic images

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US (1) US3448970A (enrdf_load_stackoverflow)
JP (1) JPS5029336B1 (enrdf_load_stackoverflow)
DE (1) DE1797010A1 (enrdf_load_stackoverflow)
GB (1) GB1214176A (enrdf_load_stackoverflow)
NL (1) NL6806979A (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3623710A (en) * 1969-10-30 1971-11-30 Xerox Corp Fixing arrangement
US3648991A (en) * 1969-08-19 1972-03-14 Xerox Corp Method and apparatus for selective fusing
US3700218A (en) * 1971-02-05 1972-10-24 Eastman Kodak Co Electrophotographic fusing apparatus
US3717747A (en) * 1970-09-04 1973-02-20 Konishiroku Photo Ind Drying means for electrophotographic copying machines
US3746834A (en) * 1971-01-22 1973-07-17 Philips Corp Device for fixing electrographic power images
US3770346A (en) * 1972-03-16 1973-11-06 Xerox Corp Method and apparatus for fuser assembly cooling in an electrostatographic machine
US3806314A (en) * 1971-03-11 1974-04-23 Fuji Photo Film Co Ltd Fixing apparatus for thermoplastic recording
US3878622A (en) * 1971-11-06 1975-04-22 Canon Kk Photographic copying apparatus
US3893245A (en) * 1972-03-28 1975-07-08 Canon Kk Photocopying apparatus
US3901591A (en) * 1973-05-18 1975-08-26 Rank Xerox Ltd Mechanism for cooling photosensitive materials in an electrophotographic copying machine
US3934112A (en) * 1974-03-04 1976-01-20 Honeywell Information Systems, Inc. Drying and fixing techniques for electrographic printing system
US4192607A (en) * 1978-07-12 1980-03-11 Eastman Kodak Company Apparatus for selectively copying documents from two different document feeders

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5330546U (enrdf_load_stackoverflow) * 1976-08-23 1978-03-16
JPS54141049U (enrdf_load_stackoverflow) * 1978-03-24 1979-10-01
JPS60232581A (ja) * 1984-05-04 1985-11-19 Dainippon Screen Mfg Co Ltd 定着装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807703A (en) * 1956-06-14 1957-09-24 Ibm Xerographic image fixing apparatus
US3117030A (en) * 1959-02-21 1964-01-07 Azoplate Corp Electrophotographic developing process and apparatus
US3245311A (en) * 1963-07-29 1966-04-12 Xerox Corp Document conveyor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2807703A (en) * 1956-06-14 1957-09-24 Ibm Xerographic image fixing apparatus
US3117030A (en) * 1959-02-21 1964-01-07 Azoplate Corp Electrophotographic developing process and apparatus
US3245311A (en) * 1963-07-29 1966-04-12 Xerox Corp Document conveyor

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3648991A (en) * 1969-08-19 1972-03-14 Xerox Corp Method and apparatus for selective fusing
US3623710A (en) * 1969-10-30 1971-11-30 Xerox Corp Fixing arrangement
US3717747A (en) * 1970-09-04 1973-02-20 Konishiroku Photo Ind Drying means for electrophotographic copying machines
US3746834A (en) * 1971-01-22 1973-07-17 Philips Corp Device for fixing electrographic power images
US3700218A (en) * 1971-02-05 1972-10-24 Eastman Kodak Co Electrophotographic fusing apparatus
US3806314A (en) * 1971-03-11 1974-04-23 Fuji Photo Film Co Ltd Fixing apparatus for thermoplastic recording
US3878622A (en) * 1971-11-06 1975-04-22 Canon Kk Photographic copying apparatus
US3770346A (en) * 1972-03-16 1973-11-06 Xerox Corp Method and apparatus for fuser assembly cooling in an electrostatographic machine
US3893245A (en) * 1972-03-28 1975-07-08 Canon Kk Photocopying apparatus
US3901591A (en) * 1973-05-18 1975-08-26 Rank Xerox Ltd Mechanism for cooling photosensitive materials in an electrophotographic copying machine
US3934112A (en) * 1974-03-04 1976-01-20 Honeywell Information Systems, Inc. Drying and fixing techniques for electrographic printing system
US4192607A (en) * 1978-07-12 1980-03-11 Eastman Kodak Company Apparatus for selectively copying documents from two different document feeders

Also Published As

Publication number Publication date
GB1214176A (en) 1970-12-02
NL6806979A (enrdf_load_stackoverflow) 1969-02-06
JPS5029336B1 (enrdf_load_stackoverflow) 1975-09-22
DE1797010A1 (de) 1970-07-16

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