Oil applicator for reproduction machine fuser

Abstract

A roll-type fuser for a reproduction or copying machine where, to obviate any tendency for the finished copy to adhere to the fuser roll surface a liquid release material is applied thereto by a liquid applicator. To prevent the application of excess release material or the uneven application of the liquid material on the fuser roll surface, a wiper, which may comprise a relatively soft roll element, bears against the roll surface to smooth out and remove excess liquid prior to contact of the fuser roll with the copy material being fused. To control the amount of release material dispensed by the applicator and, commensurate therewith, the wiping effectiveness of the wiper, a common frame, which is displaceable toward and away from the fuser roll, supports both the liquid applicator and the wiper. Adjustable bias means on the frame simultaneously controls contact pressures of both applicator and wiper with the fuser roll so that a change in the contact pressure of the applicator with the fuser roll with attendant change in the amount of release material applied to the fuser roll by the applicator effects conjointly therewith, a change in wiping ability of the wiper.

Description

This invention relates to a fusing apparatus for reproduction or copying machines, and more particularly, to an improved roll-type fusing apparatus incorporating means for controlling the amount of copy release liquid applied to the fusing roll.

In order to fix, i.e. fuse, the toner developed image of the original made by reproduction or copying machines, a fixing or fusing apparatus, commonly termed a fuser, is provided. While the fuser may take on many forms and types as, for example, a vapor fuser, heat or combination heat pressure type fusers appear most prevalent. One common type of heat-pressure fuser consists of a heated fusing roll in operative contact with relatively soft pressure roll. In this type of fuser, the copy material, i.e. paper sheets, carrying a toner delineated image thereon pass between the nip formed by the rotating fusing and pressure rolls. During this period, heat from the fuser roll together with whatever pressure is developed between the two rolls serves to fuse or fix the toner and render the image permanent.

Occasionally, fusers of this type are troubled by the tendency of the copy material to adhere or stick to the surface of the rolls, particularly to the fusing roll itself. While the reasons for this may be many and varied, the results of such adherence can be serious. Usually, at the very minimum, the copy is destroyed and the reproduction machine jammed. Occcasionally, and of more serious nature, the trapped copy may catch fire.

To obviate any problem in this respect, the surface of the fusing roll may, before contacting the copy, be coated with a release material, such as a silicone based oil. This coating tends to reduce or eliminate any tendency for the copies to stick to the surface of the fusing roll without otherwise interfering with the fusing ability of the fuser. However, application of such release material must be done discretely if excessive or non-uniform coatings are to be avoided, it being understood that too much release material may stain the copy. And even where the quantity of release material applied is carefully controlled, an excessive buildup may nevertheless occur following long periods of machine idleness, i.e. following overnight or weekend shutdown. In this latter circumstance, the applicator itself, particularly in the case of the rather popular sponge-type applicators, may over a long period of idleness, accumulate excessive amounts of the release material with the result that on first start-up of the machine, an excessive deposit of release material is made onto the fusing roll. This in turn carries over to the copy.

It is a principle object of the present invention to provide an improved fusing apparatus for reproduction and copying machines.

It is a further object of the present invention to provide an improved system for applying release material to the fusing roll of a roll-type fuser.

It is an object of the present invention to provide a fuser incorporating an improved wiper mechanism for removing excess release oil from the surface of the fusing roll prior to engagement with the material to be fused.

It is an object of the present invention to provide an improved wiper for controlling the amount of release liquid applied to the fusing roll of a fuser utilizing an O-ring wiper.

It is an object of the present invention to provide a liquid release material applying mechanism for roll-type fusers in which both the release material applicator and wiper are supported for conjoint adjusting movement to permit coordinated control thereof.

This invention relates to a reproduction machine adapted to produce copies of original documenets, the combination consisting of: a fuser for fixing the image developed on the copy material, the fuser including a cooperating pressure and heated fusing roll pair forming a fusing nip through which the copies being fused pass, a supply of liquid release material adapted for application to the surface of the fusing roll to prevent fused copy material from adhering to the fusing roll, applicator means in operative communication with the release material supply to apply the release material on the fusing roll surface, wiper means for wiping the surface of the fusing roll to remove excess release material and provide a uniform coating thereon before contact with the copy material, bias means for biasing the applicator means and the wiper means into pressure engagement with the fusing roll, and bias control means for simultaneously varying pressure between the fusing roll and both the applicator and wiper means whereby adjustment of the applicator means pressure to change the quantity of release material applied to the fusing roll automatically changes wiper means pressure to effect a corresponding change in the wiping effectiveness of the wiper means.

Other objects and advantages of the present invention will be apparent from the ensuing description and drawings, in which:

FIG. 1 is a schematic view of an exemplary reproduction or copying machine incorporating the improved fuser of the present invention;

FIG. 2 is an enlarged cross-sectional view of the reproduction machine fuser showing details of the fuser release material applying and wiping mechanism of the present invention; and

FIG. 3 is a top view in section showing details of the applying and wiping mechanism shown in FIG. 2.

Referring particularly to FIG. 1 of the drawings, an exemplary copier/reproduction machine, designated generally by the numeral 10 and incorporating the improved fuser 38 of the present invention, is there shown. As is all electrostatic systems such as the xerographic type machine illustrated, a light image of a document to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon. Thereafter, the latent image is developed with an oppositely charged developing material to form a xerographic powder or toner image, corresponding to the latent image on the plate surface. The toner image is then electrostatically transferred to a support surface where it is fused by a fusing device so that the toner image is permanently adhered to the support surface.

In machine 10, an original document 12 to be copied is placed upon a transparent support platen 14 fixedly arranged in an illumination assembly generally indicated by the reference numeral 15 and disposed at the left end of the machine. While upon the platen, the document 12 is illuminated, thereby producing image rays corresponding to the informational areas on the original. The image rays are projected by means of an optical system onto the photosensitive surface of a xerographic plate. In the exemplary copier/reproduction machine 10, the xerographic plate is in the form of a flexible photoconductive belt 17 supported in a belt assembly 18.

The support assembly 18 for photoconductive belt 17 includes three rollers 20, 21, and 22 located with parallel axes at approximately the apices of a triangle. The upper roller 22 is rotatably driven by a suitable motor and drive means (not shown) to drive belt 17 in the direction shown by the arrow in FIG. 1. During this movement of the belt, the reflected light image of the original document 12 on platen 14 is flashed upon the photoreceptor surface of belt 17 at an exposure station 25 to produce an electrostatic latent image thereon.

The continued movement of photoconductive belt 17 carries the electrostatic image through a developing station 26 in which there is positioned a developer assembly generally indicated by the reference numeral 28. There the latent electrostatic image is developed by means of toner through the use of a multiple magnetic brush system 29.

The developed electrostatic image is carried by belt 17 to the transfer station 30 where the developed image is transferred to a support surface, normally a sheet of copy paper 31, brought forward between transfer roller 32 and belt 17. In order to accomplish transfer of the developed image solely by means of the electrical bias on transfer roller 32, the copy sheet 31 is moved at substantially the same speed as belt 17. A sheet transport mechanism generally indicated at 34 is provided to advance copy sheets 31 from a paper handling mechanism generally indicated by the reference numeral 35 to transfer station 30.

Following transfer, the copy sheet 31 is stripped from belt 17 and conveyed through fuser 38 wherein the toner image is permanently fused or affixed thereto. Following fusing, the finished copy is discharged into output tray 39.

Photoconductive belt 17 comprises a photoconductive layer of selenium, which is the light receiving surface and imaging medium for the apparatus, on a conductive backing. Further details regarding the structure of the belt assembly 12 and its relationship with the machine and support therefor may be found in U.S. Pat. No. 3,730,623, issued May 1, 1973, and assigned to the same assignee.

Referring now to FIGS. 1, 2 and 3, fuser 38 includes a suitable housing 40 within which is disposed a lower heated fuser roll 41 and an upper back-up or pressure roll 42, rolls 41, 42 cooperating to form a nip 43 through which the copy sheets 31 pass. Rolls 41, 42 are suitably supported for rotation and driven in unison by a suitable drive means (not shown). Back-up roll 42 includes a rigid internal core 64 which may be steel, for example, over which a sleeve-like cover 65 of flexible material having non-stick properties, such as Teflon, is disposed. The fuser roll 41 similarly has a rigid internal core 66 which may, for example, be steel, having a relatively thick sleeve-like covering 67 thereover. The fuser roll sleeve 67 is comprised of a flexible material, one such material being silicon rubber. To heat fuser roll 41, a lamp 44 is disposed within the fuser roll core 66, core 66 having a suitable opening 68 for receipt of lamp 44. In this arrangement, heat energy from lamp 44 permeates through the metal core 66 and outer sleeve 67 to heat the surface of roll 41 to the requisite temperature required to fuse the toner delineated images on the copy sheets 31. As will be understood by those skilled in the art, other heating lamp arrangements or other heating sources may be used instead of the arrangement illustrated.

To enhance the heating efficiency of fuser 38 and reduce any tendency for the toner bearing sheets 31 to stick to fuser roll 41, a suitable release material or agent is applied to the surface of fuser roll 41. While the release material may comprise any suitable liquid, a preferred material is silicone oil.

A supply of liquid release material 70 is held in a sump 71. Sump 71, which comprises a liquid container open at the top, is suitably supported within fuser housing 38 in spaced relationship below fuser roll 41. Sump 71 extends across the width of roll 41.

To raise the release material 70 up to the fuser roll 41 and apply the material to the roll surface, a sponge-like applicator 73 is provided which extends across the width of fuser roll 41. Applicator 73 comprises a relatively large, generally rectangular shaped element of a size sufficient to allow the mid-portion 74 thereof to ride against the surface of roll 41 and the trailing or depending ends 75 thereof to rest in sump 71.

A plate-like frame member 76 serves to support both applicator 73 and, as will appear herein, wiper 95. Frame 76 is generally rectangular and swingably supported on transverse rod 77 across the mid portion thereof. Rod 77, which is attached to the underside of frame member 76 by suitable means, is in turn rotatably journaled in the opposing sides 78 of sump 71. One end 79 of frame member 76 has a pair of substantially parallel elongated slot-like openings 80, 81 therethrough, the length of which are at least equal to the operating width of fuser roll 41. As will appear, applicator 73 for the release material 70 is, in effect, threaded through slots 80, 81, the portion of frame member 76 between slots 80, 81 serving to support the mid portion 74 of applicator 73 against the surface of fuser roll 41 with the loose ends 75 of applicator 73 projecting down from frame member 76 into the sump 71.

The opposite end 82 of frame member 76 is configured in the shape of an elongated recess or trench which extends below and parallel to fuser roll 41. The length of trench 82 is at least equal to and preferably slightly greater than the operating width of fuser roll 41.

An elongated wiper support 83, the width of which is slightly less than the width of trench 82, is slidably disposed within the trench 82 for up and down movement toward and away from fuser roll 41. The length of wiper support 83 is at least equal to the operating width of fuser roll 41.

To maintain applicator 73 and wiper 95 in operating contact with the surface of fuser roll 41, springs 85 are provided at spaced points along the length of trench 82. To prevent unwarranted displacement of springs 85, base 86 of trench 82 has suitable openings 87 therein through which the depending stem 92 of tension plate 91 projects. A downwardly projecting locating rod 89, supported from the base of wiper support 83, extends through spring 85 and tension plate 91. The lower portion of spring 85 rests against the tension plate 91. The outer periphery of the depending stem 92 of plate 91 is threaded, and cooperating threads (not shown) are provided on the surface of opening 87. By this arrangement, spring plate 91 may be selectively raised or lowered relative to locating rod 89 to change the spring force applied between frame member 76 and wiper support 83.

Wiper support 83 has an elongated, generally cylindrical groove 94 along the upper edge thereof opposite fuser roll 41. A generally cylindrical wiper member 95 is disposed within slot 94, the length of wiper 95 being at least equal to the working surface of roll 41. It will be appreciated that the relative internal dimension of groove 94 and the diameter of wiper 95 are chosen so as to retain or trap wiper 95 rotatably therewithin.

Wiper 95 is preferably comprised of a relative soft rubber-like material such as Viton and is preferably in the form of a O-ring. Preferably, the diameter of groove 94 is slightly larger than the diameter of wiper 95 to permit wiper 95 to turn freely therewithin.

During use, springs 85 serve to hold both wiper 95 and applicator 73 against the surface of fuser roll 41 at a preset pressure. During operation of fuser 38, pressure and fuser rolls 40, 41 rotate in the direction indicated by the solid line arrow in FIG. 1, the sheet 31 to be fused passing through the nip formed by the rolls 40, 41 where the toner delineated image is fused. Following fusing, the finished copy is deposited in output tray 39.

As fuser roll 41 turns, applicator 73, which is impregnated with the liquid release material, wipes against the surface of roll 41 to spread or coat roll 41 with the liquid release material. The coated surface of roll 41 is thereafter smoothed by wiper 95, excess release material being removed therefrom and deposited in sump 71.

The pressure with which applicator 73 and wiper 95 bear against fuser roll 41, and hence the thickness of the coating of release material applied to roll 41, is dependent upon the pressure with which applicator 73 and wiper 95 bear against the roll surface. By turning the threaded stems 92, the pressure force exerted by springs 85 may be varied. By the construction proposed herein, any change in spring force effects a corresponding change or adjustment in the pressure with which both applicator 73 and wiper 95 bear against the surface of fuser roll 41.

While the invention has been described with reference to the structure disclosed, it is not confined to the details set forth, but is intended to cover such modifications or changes as may come within the scope of the following claims.

Claims

What is claimed is:

1. In a reproduction machine adapted to produce copies of original documents having a fuser for fixing the image developed on the copy material, the fuser comprising a cooperating pressure roll and heated fusing roll forming a fusing nip through which copies being fused pass, the combination of:

a supply of liquid release material adapted for application to the surface of the fusing roll to prevent the fused copy material from adhering to the fusing roll;

applicator means in operative communication with said liquid supply to apply said release material on said fusing roll surface;

wiper means for wiping the surface of said fusing roll to remove excess release material and provide a uniform coating of said release material before contact with said copy material;

bias means for biasing said applicator means and said wiper means into pressure engagement with said fuser roll; and

bias control means for simultaneously varying pressure between said fuser roll and both said applicator and wiper means whereby adjustment of applicator means pressure to change the quantity of release material applied to said fuser roll automatically changes wiper means pressure to effect a corresponding change in the wiping effectiveness of said wiper means.

2. The reproduction machine according to claim 1 in which said wiper means comprises a ring-like member of relatively soft rubber-like material.

3. The reproduction machine according to claim 1 including a support member for both said applicator means and said wiper means, said bias means engaging said support member to bias both said applicator and wiper means against said fuser roll.

4. In a reproduction machine adapted to produce copies of documents, said machine having cooperating pressure and heated rolls for fusing images developed on the copy material, the combination of:

applicator means to apply a liquid release material to the fuser heated roll to prevent copies from adhering thereto,

wiper means engageable with the periphery of said fuser heated roll to remove excess release material therefrom before contact with the copy material being fused; and

bias means to bias both said applicator means and said wiper means into contact with said fuser heated roller.

5. The reproduction machine according to claim 4 in which said wiper means comprises a relatively soft rubber-like element, said wiper element being substantially round in cross-section.

6. The reproduction machine according to claim 5 in which said wiper element is rotatable with said fuser heated roll.