DE2529765A1 - MELTING DEVICE - Google Patents

Description

26 863

Xerox Corporation, Rochester, N.Y. / UNITED STATES

Melting device

The invention relates to a melting device for Use when fusing toner images onto copy sheets with a heated fuser roller and a support roller that is mounted for pressure engagement with the fuser roller to form a gap with it through which the copy sheets pass, wherein the toner images contact the heated fuser roller.

In the xerographic process, a photograph becomes one to be copied Originals typically recorded in the form of a latent, electrostatic image on a photosensitive member, wherein then the latent image by the application of electroscopic marking particles, commonly referred to as toners is made visible. The visible image can then either be fixed directly on the photosensitive part or are transferred from the photosensitive member to a sheet of flat paper, whereupon it is then fixed.

There are various ways of fusing or fixing the toner particles on the carrier part, one of which is application of warmth. To electroscopically.es toner material on a

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To permanently fix or fuse the carrier element by means of heat, it is necessary to raise the temperature of the toner material to a point at which the components of the Toner materials coalesce and become sticky. This effect causes the toner to some extent off the fibers of the carrier element, which in many cases consists of paper. When the toner material cools, it causes the subsequent solidification of the toner material creates a firm connection of the same to the carrier element. As well in the xerographic as well as the electrographic recording technology For example, the use of thermal energy to fix toner images on a support member is ancient and well known.

One way of hot fusing electroscopic toner images onto a carrier has been through the passage of the carrier with that thereon located toner image by a pair of opposing rollers, at least one of which is externally or internally heated. During the operation of a fusing device of this type, the carrier element on which the toner images are placed becomes electrostatic adhere, moved through the gap formed between the rollers with the toner images contacting the fuser roller, to thereby cause the toner images to be heated within the nip. In order to melt the toner images in To convey the manner described above, the support roller of the roller pair is usually constructed so that the melting roller creates a recess in the support roller due to the compressive force pressing the rollers into engagement with each other. For this reason, the support roller has a rigid core with a relatively thick layer of an elastomer attached to it is attached and an outer layer of adhesive material. The adhesive material shows a low affinity for sticky Toner. The above-mentioned recess is continuously formed when different portions of the support roller are in and disengage, resulting in a large number of

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Bends in the outer layer. The useful life of such support rollers depends to a large extent on the ability of the the outer layer of forming material to withstand the stress of constant flexing.

The invention is based on the object of a melting device to create with a support roller that has a much longer service life than previously known rollers.

This object is achieved according to the invention in that the support roller consists of a rigid core, a layer of elastic material glued to the core and an outer layer of a copolymer of perfluoroalkyl perf1uorvinyl ether with tetrafluoroethylene, the ether having the formula ^c _n ^F 2n + 1 ~ ° ~ ^{CF = CF} 2 has.

The thickness of the elastic silicone rubber and the adhesive material are selected to easily withstand the forces of the fuser roller.

The outer layer is made of a fluorocarbon resin that from E.I. DuPont de Nemours and Co. (Inc.) and referred to as "Teflon" PFA fluorocarbon resin. These Art Harz is a perfluoropolymer which can be produced by melting and which has the carbon fluorine structure in the main chain Perfluoroalkoxy side chains combined.

Further objects and advantages of the invention emerge from the following description of exemplary embodiments with reference on the drawings. It shows:

Fig. 1 is a schematic representation of a xerographic

rule reproduction device with an embodiment of the device according to the invention for contact melting,

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Fig '. FIG. 2 shows a cross section of the melting system according to FIG

an embodiment of the invention,

Fig. 3 shows a cross section along the line III-III of

Fig. 2,

4 is a side view of the melting device

according to an embodiment of the invention, wherein the support roller and the melting roller are disengaged,

Fig. 5 is a side view of the melting device

similar to FIG. 4, the fusing roller and however, the support rollers are engaged,

6 shows a partial illustration of a flexible drive coupling, and

FIG. 7 shows a plan view of the melting device illustrated in FIG. 2 .

In the drawing, in particular in FIG. 1, there is an automatic, xerographic reproduction device 9 with an exemplary embodiment of the roller melting system according to the invention. The automatic xerographic reproduction machine comprises a xerographic platen 10 formed into a drum is. The plate has a photoconductive layer or photosensitive surface on a conductive base that is in a Frame is mounted for rotation in the direction of the arrow shown. The rotation causes the disk surface one after the other at a number of xerographic treatment stations passes by.

To explain x <; ground the individual xerographic treatment stations their function on the path of movement of the board surface is described below:

A charging station A, where the uniform electrostatic charge is applied to the photoconductive plate will,

an exposure station B, on much rather light or a Radiation patterns from copies to be reproduced are projected onto the disk surface to reduce the charge to erase in the exposed areas of the same and thereby latent, electrostatic images of the reproduced To make copies,

a development station C, on soft xerographic developer material from toner particles with an electrostatic Charge opposite to that of the latent electrostatic images on the latent Electrostatic images are poured in a cascade to form powder images to be reproduced To make copies,

a transfer station D where the powder images are electrostatically transferred from the plate surface onto a transfer material how paper is transferred, what then

by a heated pressure melting system according to a Embodiment of the present invention, which will be described below, and FIG

a drum cleaning and unloading station E, at which the plate surface is brushed to remove remaining Remove toner particles that remain on it after image transfer and where the plate is relatively

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bright light source is exposed to a substantially complete discharge of any residual electrostatic Effecting charge left on it.

Further details of the xerographic treatment station described above can be found in U.S. Patent 3,578,859 will.

A pressure and heat combining melting device 12, such as it is particularly shown in FIGS. 2 and 3, comprises a heated melting roller l6 and a support roller l8.

The structure of the melting roller l6 consists of a rigid cylindrical Part 20, which is preferably made of steel, on which end caps 22 and 22 'are suitably, e.g. Soldering, are attached. The part 20 has in one working embodiment 60mm (2 3/8 ") outside diameter. End cap 22 '(Fig. 2) is supported on a bearing 24 which is shown in a side frame part 26 of the melting device 12 working with a roller is arranged * The end cap 22 is from the hub 28 of a drive gear 30 for the fusing roller held, which in turn held by a support bearing 32 or stored, which is arranged in a lateral frame part 26 '.

During operation of the melting device 12, a carrier copy or sheet 34 (FIG. 3) is moved through the gap 36, which is formed by the engagement of the take-up roller 16 and the backup roller, so that the toner images from the take-up roller 16 are touched. To heat energy to raise the temperature of the toner particles to a suitable fusing temperature To generate a heating element 38 is mounted within the cylindrical part 20 by Heizungsso disgusting 23 and 23 '. The heating element

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may consist of a quartz heater structure with a quartz shell and a tungsten resistance heating element arranged within the same. In practice, energy is transmitted in the order of 1475 watts to the resistive heating element via electrical connections 39, to thereby increase the surface temperature of the fusing at about 193 ° C (28O ⁰ F).

In order to build up the fusing roller Io with an outer surface that have a relatively low affinity for sticky toner particles is a layer 40 of a fluorocarbon polymer, e.g. polytetrafluoroethylene (PTFE) arranged on the rigid cylindrical part 20. The layer 40 of PTFE can be a 30 to 38 µm (1.2-1.5 mils) thick and the part is 20 preferably made of thermally conductive material such as copper or aluminum. If copper is used, it should be with aluminum or nickel can be coated before the layer of PTFE is applied. The special way in which the fuser roll 1β does not form part of the present invention. Therefore, this preparation can be carried out according to known methods such as those described in U.S. Patents 3,437,032 and 3,776,760. While building the Melting roller is described here with a PTFE layer, it can also be produced without the layer and is simple have a bare metal surface.

By controlling the heat transfer to the toner is below normal Conditions actually do not expect the toner particles to settle from the copy sheet to the fuser roller. This is based on that the heat applied to the surface of the roller is insufficient to raise the temperature of the surface of the roller above the "Hot offset" temperature of the toner increase, in which the toner particles in the image areas of the toner were liquefied and a shear effect in the molten one Toner to thereby result in "hot settling".

Shearing occurs when they hold the viscous toner masses together Cohesive forces are smaller than the adhesive forces that tend to apply them to a contact surface like a Remove the melting roller.

Occasionally, however, toner particles become on the fuser roller due to insufficient application of heat to the surface thereof discontinued (i.e. "cold settling")., by insufficient Properties of the surface of the rollers or insufficient adhesion of the toner particles to the copy sheet due to the electrostatic Forces that they normally hold there. In such a case, toner particles may stick to the surface of the Melting roller with a subsequent transfer to the support roller are transferred during the times in which there is no copy paper in the gap.

In addition, toner particles can be removed from the fuser and / or support roller during fusing of double copies or simply can be recorded from the vicinity of the reproducing device.

About the possibility of toner settling on the fuser roll To minimize it is a thin layer of an organosiloxane polymer or other suitable material is applied to the surface of the fuser roller 16, thereby creating an interface between the roller surface and to form the toner particles carried by the carrier material. So the toner has a layer of low surface energy when it passes through the fusing gap, and thereby the degree of deposition of toner on the Surface of the fuser roller lowered to a minimum.

In order to apply the organosiloxane polymer, commonly known as silicone oil, to the fuser roller 16, an amount of silicone oil H-2 is contained in an oil pan hk which

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forms part of the melting device 12. About 0.65 Silicone oil in the oil sump results in a height which is extends to the tips of several ribs 45. An application part 46 is mounted within the oil pan 44 by means of a support part 48, so that the application part contacts both the silicone oil and the surface of the fusing roller 16. As shown in FIG is, one end of the applicator member is fixedly attached to the support member 48, as shown at 49, while the other end the same extends into the silicone oil and actually touches the bottom of the oil sump.

The support member 48 comprises an elongated structure that extends as far as the longitudinal axis of the heated fuser roll 16 extends and has a pair of laterally protruding pins 50 and 50 'that protrude between a pair of upwardly Ribs or channels 52 are received which are integrally formed are or are otherwise provided in the oil pan 44, whereby the support member 48 relative to the structure of the melting roller 16 is localized. The ribs prevent excessive swiveling of the oil in the oil pan when it is moved and they also act as stiffeners for the oil pan. A pair of compression springs 54, only one of which is shown, are also provided received in the channels 52 to the support member with the entire Force of about 3kg (6 lbs) to push upwards so that a good engagement of the application part with the fusing roller is achieved.

The circumference of the support part 48 is provided with a plurality of concave areas or surfaces 5 & , each of which only interacts with a section of the application part 46. If the portion of the applicator in contact with the fuser roller is so heavily loaded with toner that it loses its effectiveness in applying or cleaning, the support member 48 can be realigned so that a clean portion of the applicator with

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the fuser roll is aligned. To this new direction To perform, the oil pan 44 is removed from the frame 57 of the melting device removed by the oil pan, as can be seen in Fig. 3, is moved from right to left.

A doctor blade 58 and a carrier for the same are arranged within the oil pan so that the doctor blade 58 contacts the fuser roller 16 after oil has been applied to it by the applicator 46. The carrier 60 is provided with a pair of pins 62 which are received in openings in the oil pan 44. Springs 64 received in lugs 65 serve to press the carrier 60 and thus the scraper blade 58 into contact with the fuser roller with sufficient force (ie approximately 4kg or 8 lbs in total) so that the applied oil is measured in a thickness, so that 5 ml / copy on a sheet of 21.6 x 27.9 c ^ (8 1/2 x 11 ") is used. The doctor blade, which can be made of any material suitable for this purpose, for example a fluorosilicone elastomer with a Shore Α hardness of 80 °, is received in an elongated channel 66 of the carrier.

The support roller l8 (Fig. 2 and 3), which has approximately the same overall dimensions as the melting roller l6, consists of a rigid, generally cylindrical member 68 having an outside diameter of 44.5 mm (1 3/4 ") and a wall thickness 4.8 mm (3/16 ") and a pair of end caps 70 and 70 'received in the end portions of the cylindrical member 68. A 8.0 mm (0.315 ") thick layer 72 of elastomeric material, preferably a heat-resistant organosiloxane polymer, which is generally known as silicone rubber is adhered to the cylindrical member 68. A 0.48 mm (0.019 ") thick outer sleeve-like Layer 74 made of high temperature resistant material with a relatively low Tacky toner affinity is placed over the layer 72 of silicone rubber. The composite thickness and

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the hardness of the .Sheets 72 and 7 ² J- are such that deformation of the same by the fusing roller is possible in order to obtain a suitable length for the gap Jo (ie an area which coincides with the concave portion of the support roller). A felt pad 75 and a support 77 for the same are mounted on the frame of the melting assembly so that the mushroom pad contacts the surface of the support roller. In this way, any contamination such as toner is removed from the support roller as it rotates.

It goes without saying that the layers 72 and "JK are subjected to mechanical stress due to the deformation as these parts of the support roller pass through the gap. At present, the service life of a structure such as the support roller 18 seems to be limited by defects in layer 7 ^. These are the main defects Splintering or breaking of this layer. Until now it has been common practice to use fluorinated ethylene propylene (FEP) as the heat-resistant polymeric material for the outer layer of the support roller. On certain machines, sleeves or layers of FEP appear to be quite satisfactory. As the copying speed increases, however, it has been found that the flexural fatigue strength of sleeves made of FEP is unsatisfactory.

Flexural fatigue strength is defined as the number of cycles a strip of FEP or other material can withstand before splitting when it is stretched by $ 10 between two gripping jaws with a radius of 0.5 mm (20 mil) at a temperature of 166 ° C (330 ⁰ F) is bent 90 °. Known materials such as the FEP used in the production of support rollers result in rollers with sleeves or outer layers, the flexural fatigue strength of which is in the order of magnitude of 10,000 to 6,000 bending cycles.

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In order to improve the service life of the support roller according to the present invention, the sleeve-like layer 64 is made of a material which has a peder service life well above the previous one. Accordingly, the layer 74 is made of a copolymer of perfluoroalkyl perfluorovinyl ether with tetrafluoroethylene, in which the ether has the formula CF ₁ -. , -0-CF = CFp, where η can optionally be a number from 1 to 10 inclusive, but is preferably a number from 1 to inclusive.

A support roller 18 made with a layer 74 of PFA lasts compared to 50,000 cycles achieved with sleeves made from FEP 1.5 million bending cycles.

The end caps 70 and 70 'of the support roller 18 are in a pair lateral frame parts 76, 76 'mounted by means of bearings 78, 78'. The support roller, together with the bearings and the frame parts, can easily be removed from the combined pressure and heat melting device 12 can be removed. For this purpose, the side frame parts 76, 76 'are provided with hook-like parts in their upper sections 80, 80 ', which are received in recesses 82, 82', which are provided in a pair of pivot arms 84, 84 '. The swivel arms carry the support roller for movement in and out Engagement with the fuser roller 16 in a manner which will be explained later. Attach a pair of bolts 86, 86 ' the lowest. Sections of the side frame parts on the pivot arms 84, 84 '. The swivel arms are on the machine frame mounted on shaft journals 85.

To install the support roller 18, the hook-like parts 80, 80 'are inserted into the recesses 82, 82' and then the Screw bolts 86, 86 'screwed in. To remove the support roller, simply reverse the previous process Sequence carried out. Both the installation and the expansion

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the support roller can be carried out quickly with a minimum of hand movements. The hook-like parts 80, 80 ^f replace screw bolts similar to the screw bolts 86, 86 '. It can be seen that when the support roller is removed, when the screw bolts 86, 86 'are removed, the hook-like parts carry the support roller on the pivot arms 84, 84' so that the support roller does not have to be held until after the screw bolts have been removed. When the support roller is hot, this aspect of the support roller assembly is important. In known devices in which four screw bolts are used, it is necessary to hold the support roller when removing the screw bolts.

As can be seen in Fig. 4, the fusing roller 16 and the Support roller 18 is stored out of engagement with one another, which is either a rest position of the reproduction device 9 or a warm-up period which corresponds to switching on the reproduction device. The warm-up period is required, among other things, so that the fusing roller temperature can be brought to a predetermined level, which fuses toner particles on sheet J54 is sufficient. When the rollers 16 and 18 are disengaged are brought, the rotational movement of the support roller 18 is carried out by means of a flexible shaft 90 which connects a drive gear 88 with the support roller 18. The melting roller 16, a rotary movement is given by means of the drive gear 30 which meshes with the drive gear 88. A shear pin 91 or some other safety device associated with the hub of the gear 88 is provided to keep the gear with to couple the main drive motor, not shown, of the device via a chain, also not shown.

The ends of the flexible shaft 90 are rectangular in cross section and are received in the end cap 70 and a coupling bearing 22, which is contained in drive gear 88 for a purpose to be explained later.

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The flexible shaft 90 allows a vertical displacement of the support roller 18, as can be seen in FIG. This shift is carried out by a connecting mechanism 9 ^ (Fig. 4 and 5). During the engagement of the support roller and the melting roller, the supporting roller is driven by the melting roller and the one-way clutch bearing 92 ensures that the support roller can be driven by the melting roller in the manner of an overdrive.

While other flexible shafts can be used, the particular shaft 90 contemplated can be obtained from the company Stow Manufacturing Co. under the designation Core No. Type 899O-100 can be obtained. This particular shaft is made of helically wound wire rope to create a multilayer structure which has a generally cylindrical cross-section. The ends of the shaft are stepped to make them a general one to shape a square cross-section. In operation, the shaft rotates in a direction that tends to make its turns to attract and therefore make the shaft more rigid but flexible enough to allow the displacement mentioned above.

A modified form of flexible coupling, as shown in FIG. 1, includes a double-sliding coupling, commonly referred to as an Oldham coupling. To provide such an arrangement for coupling the support roller to a drive gear, the end cap 70 is replaced by an end cap 96 having a slot 98 in the face. A shaft bearing arranged within the coupling bearing 92 is replaced by a coupling part 100, which has a slot 102 in its circular surface similar to the slot 98, but at an angle of 90 ° to the sameΓ ~ Ε1η intermediate piece 1θ4 replaces the shaft 90 and connects the end cap 96 with the coupling part 100. For this purpose, the intermediate piece has a generally cylindrical main part with tongues ΙΟβ, ΙΟβ ¹ which are integral with the end faces

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of the intermediate piece are formed. Like the flexible shaft 90, this type of coupling can enable the support roller 18 to be displaced, however, it also allows the support roller 18 to be removed quickly from the combined pressure and heat melting device.

The link mechanism 94, as best shown in Figs. and 5 can be seen from a joint arrangement with four pivot points, which is actuated by a magnet 108 which is attached to a holding arm 110. The holding arm 110 is part of the lateral frame parts 26, 26 '. Each of the pivot arms 84 carries a differential screw 112, which in turn has a movable one Articulation point 114 carries. The articulation point 114 is a movable articulation point 120 and another via a connecting link 116 Link 118 is connected to a stationary pivot point 122. The shaft journals 85, - which the articulated arms 84, 84 ' carry, serve as a stationary pivot point and form one of the four pivot points or hinge points of the connection arrangement.

A cam follower in the form of a Roller 124 attached. The core 126 of the magnet IO8 acts as a cam which presses against the roller 124 to thereby rotate the link II8 about the pivot point 122 in the clockwise direction cause. At the same time, the movable hinge point 120 moves to the right as seen in FIG. 4 to a point substantially on a straight line drawn through the centers of pivot points 114 and 122. An adjustable buffer serves as a stop due to its contact with the pivot arm 84, as can be seen in FIG. 5. In this way the Buffer 128 the degree of movement of pivot point 120 to a location just to the left of the aforementioned line passing through the centers pivot 114 and 122 is pulled.

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A pair of compression springs 1J5O (only one of which is shown), each one for each swivel arm supports the through the fusing roller 16 forces exerted when disengaging the Support roller with the fusing roller when the link mechanism 94 is out of order, in other words when the magnets IO8 are switched off. The springs bring about a total force from% kg (8 lbs) up. It goes without saying that the size of the Force that is required on the magnet to hold the support roller and the melting roller in the gap is quite small. the required holding force is opposite to the required movement force the magnets on the order of 20 watts compared to the 320 watts that are required to keep the reels together engaged so that a total force of approximately 360 kg (800 lbs) with the hot nip (i.e. when the fuser roll at or near their working temperature) must become. A second adjustable buffer 132 formed integrally with link II8 is limited the clockwise movement of the link II8 through its engagement with the magnet 108.

The adjustment of the link mechanism 94 is done by adjustment the buffers 128 and 132. When the magnet is on, the buffer 128 should touch the pivot arms 84, 84 'so that that the center of pivot point 120 is just to the left of the line through the centers of pivot points 140 and 122. If this is the If the magnet is not switched on, the buffer I28 can be moved towards or away from the swivel arm as needed.

The nip pressure can screw by adjusting the differential 112 can be changed when the link mechanism is adjusted. A suitable gap pressure is reached when the measured Contact arc equals 11.4 mm (0.45 "). This can be done with conventional carbon paper, following known methods

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for measuring the contact arc between the support roller and the Melting roller is used.

It will be appreciated that the force exerted by the fusing would normally tend to cause a substantial shearing force to the bolt 86, 86 ^f. The side frame parts 76, 76 ^{1 are} therefore designed in such a way that they guide the mentioned shear forces via the side frames in a direction in which these forces are directed against inclined surfaces 1 ^ 4 of the pivot arms 84, 84 ¹ .

The magnet IO8 can consist of a single DC magnet from 8EC size available from Ledex Corporation, or a pair of 7EC, which can also be obtained from this company.

As shown in FIG. 7, a torque transmission shaft Ij56 connects the pivot arms 84, 84 'to ensure accurate locking by the link mechanism 94. For this purpose, the lower sections of the pivot arms are provided with crown-like projections 138, 138 'which are formed integrally with them. The shaft 136 carries a pair of crown-like sleeves 140, 140 'which engage the projections 138, 138 *, whereby the movement imparted to one of the pivot arms is transmitted to the other of the pivot arms. The sleeve l40 is fastened to the shaft with a grub screw 142, while the sleeve l40 'carries a grub screw 142' which slides in a slot 144 of the shaft 136. A coil spring 146 is engaged with a retaining ring 148 and the sleeve l40 ^r to press the sleeves with the projections I38, I38 ¹ into engagement. The shaft can be removed by simply moving it to the right against the force of the coil spring 146, as can be seen in FIG.

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A pair of fingers 150, 150 * are also shown in FIG. 7, which, as can be seen in FIG. 3, are arranged next to the exit of the gap 36. The fingers cause the Sheet 3 ^ · from the fuser roll l6. When the sheet breaks the gap leaves, it follows the rotation of the fuser roller where it contacts the top of the wiping fingers comes. The fingers are thus placed between the sheet and the fuser roller and thereby guide the sheet along a predetermined path of travel away from the fuser roller, so that it can be picked up by a transport device, not shown. The fingers can be made of a PTFE material or its top surface can be coated with PTFE to prevent the copy from sticking to it or of the toner settle on to reduce to a minimum.

As seen in Fig. 3, there is a thermistor 152 and a holder 15 ^ for the same pivotable in contact with the melting roller 16 arranged. The thermistor can be of any suitable construction, such as that disclosed in U.S. patent application Ser. 364 178, filed May 25, 1973 * which is the Applicant of the present application has been assigned. The temperature of the fuser roller can be related to the output of the thermistor can be controlled by a control circuit such as that described in U.S. Patent 3,327,096.

The entire combined pressure and heat fusing device 12 is within the reproduction machine by upper and lower ones Sled mounted and assigned mounting arms. Only the upper slide I60 is shown. Suitable sled will be sold by Accuride Co. and bear part number C-30I-17-LC. The carriages and associated fittings support the combined pressure and heat fusing device in a manner that it allows them to go in and out of the machine in one direction

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Push machine that coincides with the longitudinal axis of rollers 16 and 18.

While the invention with reference to a preferred embodiment has been described, it is understood that various modifications can be made without departing from the spirit of the invention can be carried out. Therefore, this description is not intended to be limiting.

Briefly summarized by the invention is a support roller for use in a melting device for fixing Toner images are created on copy sheets through the application of heat and pressure. The support role is characterized by a rigid core covered with a relatively thick layer of an elastomer over which a relatively thin layer is made of a material with high flexural fatigue strength, which forms the outer surface of the support roller.

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Claims (1)

Claims Fusing device for use in fixing toner images on copy sheets with a heated fusing roller and a support roller which is mounted for pressure engagement with the fusing roller in order to form a gap with it through which the copy sheets pass, whereby the toner images touch the heated fusing roller characterized in that the support roller consists of a rigid core, a layer of elastic material glued to the core and an outer layer of a copolymer of perfluoroalkyl perfluorovinyl ether with tetrafluoroethylene, the ether having the formula ^c _n ^P 2n + l "" ° ~ ^{CF = CF} 2 ^has * 2 «Device according to claim 1, characterized in that the ether has the formula C _n Fp _{n + 1} -O-CF = CFp and η is a number from 1 to 5 inclusive. 3. Device according to claim 2, characterized in that the melting roller is heated from the inside. 2λ Blank page