|Publication number||US3868744 A|
|Publication date||Mar 4, 1975|
|Filing date||Nov 24, 1972|
|Priority date||Jan 28, 1972|
|Publication number||US 3868744 A, US 3868744A, US-A-3868744, US3868744 A, US3868744A|
|Inventors||Thettu Raghulinga R|
|Original Assignee||Xerox Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (17), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Mar. 4, 1975 CLEANING APPARATUS FOR' HEATED 3,649,992 1 PRESSURE ROLL FUSER 3/1972 Thettu........................15/256.52 3.693547 9/1972 Morgan............................ 15/256 52 Inventor: Ra'ghulinga R. Thettu, Webster,
Primary Euuniner-Harvey C. Hornsby Assistant E.\'aminer-C. K. Moore Assignee:
Xerox Corporation, Stamford, Conn.
ABSTRACT An improved cleaning apparatus for cleaning the re- '22 Filed: Nov. 24, 1972 sidual toner particles from the heated fuser roll of a A'PPL 309,543 heated pressure fusing system in an electrostatic copy Rdated Application'nata machine The improved cleaning apparatus includes a Continuation of Ser. No.
carriage supporting a plurality of cleaning rollers in contact with the surface of the heated fuser roll. A pressure loading mechanism applies a force of about 4 22l.569. Jan. 28, 1972,
to 8 pounds onto the carriage and cleaning rollers against the surface of the heated fuser roll. Each cleaning roller hasa core member which is wrapped in a soft thermally insulating material such that under the pressure loading condition the surface of the cleaning roller conforms to that of the heated fuser roll. The exterior surface of each cleaning roller has a toner wnai //I17OO6 S 9 u 0 26 9 $0 lJ Z 20 4 5G2H M 4 6Z .S 5 2 9 l 3 5 2 m o a m u n .U .2 "nu53 unu 4 "n mmmfi l d mn s urn m"w4H m S O Qu H mm UIF ii] 2 8 555 iii.
References Cited UNITED STATES PATENTS coating mixed with silicone oil to insure proper release of the residual toner from the heated fuser roll onto the cleaning roller.
' 10 Claims, 6 Drawing Figures 09 O6 4 59 ll. .2 n .MC S um ah HO 7fi 57 99 ll l ammen 5 sum 2 or '3 LOADING MECH.
CLEANING APPARATUS FOR HEATED PRESSURE ROLL FUSER This is a continuation of application Ser. No. 221,569, filed Jan. 28, 1972 and now abandoned.
This invention relates to fusing systems and in particular to an improved apparatus for removing toner particles from the fuser roll of a heated pressure fusing system.
In the practice of xerography as described in US. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic surface is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where the light strikes the layer. The undis- Charged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.
The latent electrostatic. image can then be developed by contacting it with a finely divided electrostatically attractable material such as a powder. The powder is held in image areas by the electrostatic charges on the layer. Where the charge field is greatest, the greatest amount of powder is deposited; where the charge field is least, little or no material is deposited. Thus, a powder image is produced in conformity with the light image of the document or object being reproduced. The powder'is subsequently transferred to a sheet of paper or other surface and suitably affixed thereto to form a permanent print.
One typical device for fixing the toner particles to the backing sheet is by a heated pressure fuser roll system in which the copy sheet is passed through the nip of a Teflon coated heated fuser roll and a backup roll as described in US. Pat. Nos. 3,256,002 and 3,268,35l. In such fusing systems, care must be taken to remove unwanted toner particles from the heated fuser roll prior to its contact with the copy being fused. lf care is not taken to keep the fuser roll free of toner particles, these toner particles can build up on the face of the fuser roll and degrade the quality of the fix by removing the fusing properties on the surface of the roll contacting the copy sheet and toner images. Furthermore, such unwanted toner particles can be released from the fusing roll upon its subsequent contact with the toner image to fuse toner particles to thecopy sheet in non-imaged areas.
Normally unwanted or residual toner particles are removed fromthe surface of the -fuser roll by a wick which also dispenses silicone oil to maintain the proper surface condition for release of the toner particles onto the wick as described in copending application Ser. No.
l64,370 filed on July 20, 1971 entitled Improved Wicking Apparatus and commonly assigned with the instant application. It has been found that with the high-speed duplicating machines in present use that the wick devices often require frequent replacement which becomes costly. The present invention has the purpose ofimproving the cleaning ofthe heated fuser roll to extend the life of the wick device and also improve cleaning capability. Additionally, the cleaning apparatus of the invention is an improvement of the cleaning apparatus described in copending application Ser. No.
889,204 filed on Dec. 30, 1969 and commonly assigned herewith.
It is therefore an object of the present invention to improve heated pressure fusing systems.
It is another object of the present invention to enhance cleaning of fuser roll having hard surfaces.
It is another object of the invention to provide cleaning rollers which conform with fuser roll surfaces being cleaned and maintain uniform contact therewith.
It is still another object of the present invention to prevent uneven cleaning of fuser rolls.
It is still another object of the present invention to assure cleaning of fuser rolls by cleaning rollers which will not stick to the fuser rolls.
It is still another object of the present invention to minimize unnecessary maintenance of copier/duplicator systems.
These and other objects of the instant invention are obtained by a new and improved cleaning roller assembly which comprises one or more cleaning rollers having a conformable surface which is urged into pressure contact with a heated fuser roll surface being cleaned and-which has sufficient lubrication to prevent sticking during the cleaning operation.
Further objects of this invention together with additional features and advantages thereof will become apparent from the following detailed description of the embodiment of the invention when read in conjunction with the accompanying drawings wherein:
FIG. 1 is a schematic representation of an automatic xerographic reproducing machine incorporating a heated pressure fusing system utilizing the improved cleaning roller assembly of the present invention;
FIG. 2 is a side elevational view of the heated pressure fusing system and improved cleaning roller assemy;
Hg. 3 is an isometric view of the improved cleaning roller assembly according to the present invention with parts'broken away to illustrate certain details;
FIG. 4 is an end view of the assembly; and
FIGS. 5 and 6 are side views of different embodiments of the cleaning roller jacket construction.
Referring now to the drawings as shown in FIG. 1 an embodiment of the invention is a suitable environment such as an automatic xerographic reproducing machine. The automatic xerographic reproducing machine includes axerographic plate or surface formed in the shape of a drum. The plate has a photoconductive layer or light receiving surface on a conductive backing journaled in a frame to rotate in a direction indicated by the arrow. The rotation will cause the plate surface to sequentially pass a series of xerographic processing stations.
For purposes of the present disclosure the several xerographic processing stations in the path of movement of the plate surface may be described functionally as follows:
a charging station A which the uniform electrostatic charge is deposited onto the photoconductive plate;
an exposure station B at which light or radiation pattern of copies to be reproduced is projected onto the plate surface to dissipate the charge in the exposed areas thereof to thereby form a latent electrostatic image of the copies to be reproduced;
a developing station C at which xerographic developing material including toner particles have an electrostatic charge opposite to that of .the latent electrostatic image is cascaded over the latent electrostatic image to form a powdered image in configuration of the copy being reproduced; v
a transfer station D which the powdered image is electrostatically transferred from the plate surface to a transfer material such as paper which is then passed through heated pressure fusing system having an improved cleaning roller assembly according to the present invention aswill be described hereinafter; and
a drum cleaning and discharge station E at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and at which the plate is exposed'to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.
For further details of the xerographic processing stations, above reference is made tocopending application Ser. No. 838,902filed July 3, 1969.
Referring now in particular to FIG. 2 there is shown details of the heated pressure fusing system which ineludes-a heated fuser roll 16 and a backup pressure roll 18. Fuser roll 16 is'a hollow circular cylinder with a metallic core 20 and a Teflon layer 22. A quartz lamp 24 serves as a source of thermal energy and'is located at the center of the fuser roll. Power to the lamp is controlled by a thermal sensor generally called a thermister contacting the periphery of the fuser roll as described, for example, in U.S. Pat. No. 3,357,249. The backup roll 18 is also a circular cylinder and is made up of a metal core 30 surrounded by a thick rubber layer 32 and also a Teflon layer 34 to prevent soaking silicone oil into rubber layer 32 and subsequent swelling.
When the'two rollers 16 and 18 are engaged as shown in FIG. 2 the applied load deforms the rubber in the pressure roll to provide the nip with a finite width. The copy sheet 40 electrostatically bearing the toner images 42 on the underside is brought into contact with the nip of the rolls with the toner image contacting the fuser roll 16. For a given temperature of the fuser roll, the fusing rate will depend upon the contact arc length of the support material against the dwell time, i.e., the time the toner images remain between the fuser roll 16 tion mounting (not shown) as details of the mounting form no part of the present invention. Applicator roll 52 is used to convey a thin film of oil to the bottom face 55' of the wicking assembly as te applicator roll is rotated in the direction shown by the arrow. Desirably, the applicator roll 52 is driven by an oil dispensing motor 58 which is energized during the fusing operation for a period depending upon the number of copies being produced.
In accordance with the present invention, cleaning roller apparatus 10 maintains the working heated surface of fuser roll 16 in a toner free condition thereby preventing unwanted residual toner particles from being redeposited upon subsequent copies as they are fused as will now be explained. The cleaning roller apparatus of the invention cleans any residual toner particles adhering to the surface of the heated-fuser roll continuously and uniformly during the cleaning operation. The cleaning roller apparatus includes a plurality of cleaning rollers 70 and 71 which are constructed so as to have a soft and conformable surface to insure proper contact with the relatively hard exterior of the heated fuser roll 16. Cleaning rollers 70 and 71 are mounted and desirably maintains a force of about 4 to about 8 pounds during the cleaning operation for a purpose to be described.
Since each of the cleaning rollers has the same construction, it is deemed necessary to describe only one and the backuproll l8. Dwell time can be varied either by changing the surface velocity of the rollsor by vary- 'ing the contact arc length and holding the speed of the roll the same, Contact arc lengthdepends on the softness of the rubberon backup roll 18 and on the amount of pressure between the rolls l6 and 18. The mechani'sm for driving the rolls and for lowering and raising the rolls into contact can be accomplished by any suitwicking apparatus of the present invention which is successful in applying athin film of offset preventing liquid such as silicone oil to the Teflon surface 22 of the v fuser roll 16 such that toner offset is prevented as will be described hereinafter.
An oil dispensing apparatus 45 includes wicking assembly 48, an oil pan for maintaining a supply of silicone oil 51 and an applicator roll 52. The oil pan is loaded against the heated fuser'roll 16 by a spring acof them. The cleaning roller comprises a metal core 81 which is made out of a suitable lightweight material such as aluminum. Core 81 is covered with a soft deformable jacket 83 to render a surface conformable to the heated fuser roll under the force of the loading mechanism. Any suitable material may be used for the jacket which has the proper thermal and deforming properties. A preferred material is Nomex manufactured under the registered trademark of Dupont Corporation, Wilmington, Delaware. The Nomex material may be placed onto the core in any suitablemanner. It has been found that this may be accomplished by either braiding (FIG. 3) or wrapping in spiral form (FIG. 5)
or insertion in a tubular form (FIG. 6). In each of these constructions the Nomex material is then bonded to the core by an adhesive. Any suitable adhesive may be used, such as, Hypalon manufactured under the registered trademark of Dupont Corporation, Wilmington, Delaware, or Ply-O-Bond HT manufactured under the registered trademark of. Goodyear Corporation, Akron, Ohio.
The surface of the Nomex material is coated with a layer'85 of toner material which may be applied in any suitable manner, such as, by spraying, dipping, or sprinkling, or combinations thereof. The toner layer or coating desirably is uniform in thickness ranging from about .001 to about .005 inches. Any suitable toner material may be used. Typical toner materials are described in U.S. Pat. No. Re. 25,l36 to Carlson.
In order to insure that the bond between the surface of the cleaning roller and the residual toner on the heated roll 16 is sufficiently strong to overcome the bond between the residual toner and the fuser roll, the
toner coating on the cleaning roll is coated witha thin layer of silicone oil. The layer of silicone oil ranges from about .005 to about .1 microns. It has been found that the amount of silicone oil available on the fuser roll during start periods between the copies being produced and the end of the cycle is sufficient tokeep enough oil on the cleaning roller surface to maintain proper cleaning. The cleaning roller is adjusted to touch the surface of the fuser roll to enable the cleaning roller to become coated with silicone oil for a brief interval at the start of every fuser operation. In this manner the cleaning roller maintains a sufficient oil film even during short operations.
The cleaning roller is supported on a bearing assembly 90 (FIG. 3) which enablesthe cleaning roller to rotate freely when held against the surface of the heated fuser roll 16. Bearing assembly 90 includes a shaft 91 which is held stationary by the carriage 73. The shaft carries a plurality of metal bearings 92 spaced along the shaft axis. Each of the bearings 92 is held on the shaft by retaining rings 95. Desirably there is a clearance of approximately .125 inches between the bearing and the retaining ring to enable the bearing to float on the shaft which enables the cleaning roller to oscillate while cleaning.
In operation when the toner material coating on the cleaning roller is raised to a sufficient temperature ranging from about 250 F to about 400 Fthe toner particles soften and change their state from a solid to aplastic or semi-molten state. During the plastic state,
particles to be cleaned and released from the entire sur' face of the heated fuser roll.
The loading of the carriage carrying the cleaning rollers into pressure contact with the heated fuser roll maintains the necessary temperature to the cleaning rollers to maintain their plastic state as well as enabling the cleaning rollers to conform and make uniform contact with theheated fuser roll.
lt has been found that as the cleaning roller surfaces are covered by removed residual toner that the diameter increases by about .250 inches before any change in loading is necessitated. While one cleaning roller is sufficient to do the job at least two cleaning rollers ensure a safer, more reliable cleaning operation.
While the instant invention as to its object and advantages has been described as being carried in a specific embodiment thereof it is not intended to be limited thereby but it is intended to becove'red broadly within the scope of the appended claims.
What is claimed is:
1. In a fusing system for fusing toner images in an 6 electrostatic copying machine in which a relatively hard heated roll surface is used to fix the toner images to copy sheet material, an improved cleaning apparatus for cleaning toner offset onto the heated roll surface comprising a carriage means supporting at least one cleaning roller member in contact with the heated roll surface to be cleaned,
pressure loading means for urging said carriage means towards the heated roll surface at a predetermined pressure,
said cleaning roller beingexteriorly coated with toner layer covered with a silicone oil film to create sufficient surface energy to collect toner from the heated roll surface,
said cleaning roller member further including a core member having a soft deformable thermally insulating cover means to conform to the surface of the heated roll to effect uniform cleaning thereof.
2. Apparatus to claim 1 wherein said toner layer thickness is at least .001 inches.
3. Apparatus according to claim 2'wherein said silicone oil film thickness ranges from about .005 to about .1 microns.
4. Apparatus according to claim 1 wherein said insulating cover means is in braided form:
5. Apparatus according to claim 1 wherein said insulating cover means is-wrapped in spiral form.
6. Apparatus according to claim 1 wherein said insulating cover means is in tubular form.
7. Apparatus according to claim 1 wherein said core member is supported to rotate on bearings mounted on a shaft fixed to said carriage means.
8. Apparatus according to claim 7 wherein said pressure loading means exerts a force ranging from about 4 to about 8 pounds.
9. Apparatus according to claim 8 wherein at least two cleaning roller members are supported on the carriage means.
10. In a fusing system for fusing toner images in an electrostatic copying machine in which a relatively hard heated roll surface is used to fix the toner images to copy sheet material. an improved cleaning apparatus for cleaning toner offset onto the heated roll surface comprising a carriage supporting at least one cleaning roller member in contact with the heated roll surface to be cleaned,
pressure loading means for urging said carriage towards the heated roll surface at a predetermined pressure,
said cleaning roller being exteriorly coated with a thermoplastic layer to create sufficient surface energy to collect toner from the heated roll surface, said cleaning roller member further including a core member have a soft deformable thermally insulating cover means to conform to the surface of the heated roll to effect uniform cleaning thereof.
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|U.S. Classification||15/256.52, 399/327|