US3566076A

US3566076A - Toner fixing apparatus

Info

Publication number: US3566076A
Application number: US838777A
Authority: US
Inventors: Joseph Fantuzzo; Thomas L Thourson; John A Mcinally
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1969-07-03
Filing date: 1969-07-03
Publication date: 1971-02-23
Anticipated expiration: 1988-02-23
Also published as: DE2033127A1; JPS5332261B1; GB1256471A

Abstract

Apparatus for fixing toner images to a support material during movement through first and second stations. The first station is a cold roll fixer to partially fix the image to the support material. The second is a radiant energy source to complete the fix.

Description

United States Patent Inventors Appl. No.

Filed Patented Assignee Joseph Fantuuo Webster;

John A. Mclnally; Thomas L. Thourson, Penfield, N.Y.

July 3, 1969 Feb. 23, 197 l Xerox Corporation Rochester, N.Y.

TONER FIXING APPARATUS 7 Claims, 2 Drawing Figs.

US. Cl

Int. Cl

newoiiliiilijjjii "IIIIIIIIIIIIIIIIIIIL.IIIII 21 References Cited UNITED STATES PATENTS 7/1959 Schulze l18/637UX 10/1961 Streich, Sr. 118/637 5/1964 Van Dorn 263/6EUX 8/1964 Streich, Sr. 118/637 7/1968 Verderber.... 219/216X 5/1969 Michaels 219/216 Primary Examiner-J. V. Truhe Assistant Examiner-Peter W. Gowdey Attorneyr-Paul M. Enlow, Norman E. Ralabate, Ronald Zibelli Schrader and Michael J. Colitz, Jr.

ABSTRACT: Apparatus for fixing toner images to a support material during movement through first and second stations. The first station is a cold roll fixer to partially fix the image to the support material. The second is a radiant energy source to complete the fix.

PATENTED FEB23 1971 v SHEET 1 0F 2 INVENTOR.

JOSEPH FANTUZZO JOHN A. MC INALLY BY THOMAS L. THOURSON W 4L.

ATTORNEY Tours rrxmc APPARATUS This case relates to the fixing of toner images to a support material and more particularly to the fixing of toner images to a backing sheet by a primary partial roll fix of the image followed by the exposing of the image to radiant energy source sufficient to permanently bond the toner to the support material.

In the process of xerography as described in US. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface including 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, this 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 undischarged layer thus forms 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 material 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 being reproduced. The powder is subsequently transferred to a sheet of paper or other final backing member and suitably affixed thereto to form a permanent print In the alternative, the final backing surface may be provided with a photoconductive layer. In such case the final backing sheet would be charged, exposed, developed and directly fused without the transfer step.

Many forms of imaging-fixing techniques are known today. The most prevalent include vapor fixing, heat fixing, heatpressure rolling and radiation fixing. Each of these techniques suffers from difficiencies which make its use impractical or difficult for specific applications in xerography. In general, it has been found difficult to construct the universal fuser which would be characterized by high efficiency, reliability, a short warm up time, and overall ease of control. Fixing techniques relying on the application of pressure and heat have inherent problems with the toner image partially offsetting to the roll due to fluid nature of the toner thus resulting in poor resolution of the copy and subsequent copies fused thereby. Vapor fixing, which typically employs a toxic solvent, is commercially undesirable due to its odor. And apparatus relying on oven type fusing requires heat insulation of the fuser from the surrounding ambient air to attain good efficiency. This last type of system is often accompanied by burning and scorching of the support material.

It is therefore an object of this invention to improve fixing of toner images to a support material.

A further object of this invention is to fuse toner images absent the above-noted difficiencies.

Another object of this invention is to improve the efficiency of apparatus for fusing an image to a backing material.

A further object of this invention is to fuse toner images by a radiant fuser after precompaction.

A further object of this invention is to precompact toner images by roller means prior to completely fixing them by radiant energy.

These and other objects of the present invention are attained by moving a toner image electrostatically adhering to a support sheet between compacting rollers and then moving the precompacted toner image adjacent a source of radiant energy to effect the fix between the toner and sheet.

For a better understanding of the invention as well as other FIG. I is a schematic illustration of a continuous and automatic xerographic reproducing machine employing the fixing apparatus of the instant invention and FIG. 2 is a perspective view of the fuser assembly with parts broken away to show internal constructions thereof.

Referring now to the drawings, there is shown schematically in FIG. 1 an embodiment of the subject invention in a suitable environment such as a xerographic reproducing machine adapted for continuous and automatic operation. The machine includes a xerographic plate or surface 10 formed in the shape of a drum. The plate has a photoconductive or light responsive layer on a conductive backing, journaled in a frame to rotate in the direction indicated by the arrow. The rotation will cause the plate to sequentially pass a series of xerographic processing stations. For the purpose 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 at which a uniform electrostatic charge is deposited on the photoconductive plate;

An exposure station B at which a light or radiation pattern of the copy 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 copy to be reproduced;

A developing station C at which xerographic developing material, including toner particles having an electrostatic charge opposite that of the latent electrostatic image is cascaded over the plate surface whereby the toner particles adhere to the latent electrostatic image to form a visible toner image in a configuration of the copy being reproduced;

A transfer station D at which the toner image is electrostatically transferred from the plate surface to a transfer material or asupport surface and A drum-cleaning station E at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

It is felt that the preceding description of the xerographic process is sufficient for an understanding of the instant invention. Further details of this type of xerographic apparatus may be had by reference to US. Pat. No. 3,301,126 issued to R.F. Osborne et al.

In addition to the apparatus disclosed in aforementioned Osborne et al. patent, the xerographic machine is also provided with fixing apparatus to permanently bond the toner image to the backing sheet and which forms the basis of the in stant invention.

The sheet material, preferably paper, which is to form the final support for the permanent toner image is shown in FIG. 1 as a web of material 12 wound about a support role 14 at a backing material supply station and takeup roll 16 at a backing material-receiving station. The web is directed along a feed path to pass the transfer station D and the fusing or fixing station 18. Idler rolls 20, 22, 24, 26 and 28 are provided for guiding the sheet material along this feed path. The takeup roll 16 is driven by a power source MOT-l schematically shown in FIG. 1 to rotate the takeup roll so that the sheet material moves at a constant rate of speed, the same as that of the xerographic drum which is driven by power source MOT- 2. The support roll 14 is preferably mounted with suitable braking means to keep the web material in a state of slight tension as it moves through its path of movement. While the feeding means for the support material is shown as moving a web of paper, any other suitable support material could be used in the illustrated web form or even in a cut sheet form. If a cut sheet were to be used, suitable support means for moving the sheet through the paper feed path would be required as of the objects and further features thereof, reference is had to the following invention to be read in conjunction with the drawings wherein:

type disclosed in the aforementioned Osborne et al. patent.

As sheet material leaves the transfer station, whereat the image is received on the support material, the toner will be electrostatically adhering thereto. The sheet will then pass through the fixing apparatus before it is taken up on the takeup roll. The fixing apparatus 18 has a primary fixing station 30 including rollers 32 and 34 coupled to each other through gears 36 and 38 to rotate at a common linear speed, by power source MOT-3, at the same speed as that of the sup port material and xerographic plate. The upper roller 32 is adjustable toward and away from the lower roller 34 due to the mounting of its support shaft 40 on side support members 42 and 44. Setscrews 46 and 48 adjustably hold the support members 42 and 44 on fixed. rod 50 fixedly mounted onthe side frames 52 of the'machine. The adjustable mounting of the upper roll 32 permits the operator to selectively vary the pressure exerted by the rolls on the sheet material moving therebetween. Since the thicknesses of the sheet material as well as the material thereof may vary, this adjustability is desirable. Furthermore, separating these rolls during machine nonuse extend their life.

These rollers function to precondition the toner image on the support material prior to its moving into the secondary or final fixing station 54 which is in the form of a radiant fuser. A preferred radiant fuser shown is a xenon flash tube 56 adapted to be energized through a capacitor bank to discharge radiant energy at an electromagnetic wave length such that theenergy will be absorbed by the toner particles but not by the support material. Y I

The cavity 58 in which the flash tube 56 is supported is adapted to shield the surrounding environment from its discharge and includes entrance and

egress ports

60 and 62 through which the sheet material may pass. in this embodiment, the entire inner surface 64 of the cavity is completely formed of a reflective material such that all of the emitted energy will be reflected and rerefiected until it is absorbed by the toner particles of the image. This type of fusing device is disclosed in pending application Ser. No. 707,612 filed Feb. 23, 1968 in the name of 1D. Rees. This type of radiant fuser is easily energized and controlled and can function with virtually no warm up time. Another suitable radiation type fuser is dis closed in pending application Ser. No. 85,971 filed Oct. H, 1966 in the name of G.A. Aser et al. According to that disclosure, the radiation discharge is effected by a quartz lamp, electrically energized in a steady radiant or nonflashing state.

Radiant fusers have the ability to fuse the toner particles by passing energy thereto such that when the energy is received by the toner particle only the toner'particles will receive the energy and dissipate it to the surrounding thermoplastic mass thereof to cause its liquification and, consequently, its adhesion to the backing material. Toner particles of the type described in Carlson patent Re. 25,136 and include carbon or the like pigments in a thermoplastic binder such that the melting of the binder causes the adhesion of the marking particles to the support material. Radiant energy for fusing is received by only the toner particle to cause the'fixing thereof to the backing material to form the permanent copy since the radiant emissions are at a wavelength whereat they are not absorbed by the copy sheet itself.

Fusers of the radiant type are characterized by the fact that improperly deposited toner particles in background areas of the copy will not be fused thereto by the radiant energy. This is because the surface area to volume ratio of a single toner particle, or a few random toner particles in the background, is too great to receive sufi'icient radiant energy to cause it to be liquified for adhesion to the support material. Such is not the case with clusters of toner particles in image areas of the copy. It is for this reason that it has been found desirable to use a cleaning brush 66 after the fusing station for the removing of this background toner with no ill effects to the fused toner image.

The use of the rollers 32 and 34 in advance of the radiant fuser has been found to increase the efficiency of the radiant fuser and, in tandem therewith, constitutes a highly efficient fusing system. With conventional and commercially acceptable toner images being received by the backing material, rollers having stainless steel exteriors and exerting between 50 and 200 pounds per linear inch pressure were found excellent for preconditioning the image prior to radiant fusing for high fusing quality. This partial roll fixing reduced the peaks of remove air gaps between the toner particles, causing some cohesion between the toner particles of the image while pushing the toner mass into the paper with slight adhesion therebetween. This partial fix was caused by the energy imparted to the toner through the pressure of the rollers. In all, the toner height across the image areas was substantially unifiedand, perhaps of more significance, the surface area to volume ratio in the images was decreased to permit the irradiation to be more effective. The precompaction thus reduced the heat loss due to the radiant fusing to render the total system more'efficient.

The use of the roll fixing to precondition the toner image prior to its final fixing is readily achievable with the roll fusers described, operated in an unheated condition. While the addition of heat to the rollers would probably further decrease the energy output requiredby the radiant fuser, such was not found necessary. Furthermore, the use of the cold rolls with the stainless steel surfaces resulted in virtually no offsetting of the toner image to the rollers which can be caused if heated rollers cause a more liquefying effect on the toner.

In the combination fuser of the type herein described, it was found that toner images of a commercial nature could be optirnumly fused with a radiation output at about 9.5 joules per square inch after precompaction. This is a substantial power decrease from the l l joules per square inch which would normally be required without the initial'rolling the toner image. Such FIGS. are by way of example only to illustrate the efficiency gained by the roll fusing. These power requirements are, however, highly variable since they would depend on the type of support material, toners employed and various other operating parameters in the system.

While the instant invention herein is carried out in a specific embodiment, it is not intended to be limited thereby but it is intended to be covered broadly within the scope of the appended claims.

We claim:

1. In a xerographic machine of the type wherein toner images are electrostatically held to a support material which is moved along a support material feed path through the machine, fixing means including:

a radiant energy power source located along the support material feed path to fix the toner images to the support material moved therepast; and

roller means located adjacent the support material feed path in advance of said radiant energy power source, said roller means providing at least 50 pounds pressure per linear inch and extending generally transversly of said support material feed path and of such length as to precompact the effective toner image on said support material.

2. The apparatus as set forth in claim 1 wherein said roller means are unheated stainless steel rollers adapted to apply between 50 and 200 pounds pressure per linear inch to the toner images.

3. The apparatus as set forth in claim 2 wherein said radiant energy source is a xenon flash tube within a reflective cavity.

4. A xerographic reproducing machine including means to electrostatically adhere a toner image to a support material, a receiving station to receive the support material with the toner image, means to move the support material along a support material feed path from said image-adhering means to said receiving station and fusing means located along the support material feed path, said fusing means including:

a pair of rollers positioned on opposite sides of the support material feed path through which the support material must pass as it is moved to said receiving station said roller means providing at least 50 pounds pressure per linear inch and extending generally transversely of said support material feed path and of such length as to partially fix the efiective toner image on said support materimeans to rotate said rollers at a linear speed equal to that of the movement of the paper; and radiant fusing means positioned between said rollers and said receiving station to complete the fix of the toner image to the support material. 5. The apparatus as set forth in claim 4 wherein said radiant energy source is a xenon flash tube capable of emitting energy at a wavelength whereat it is absorbed by the toner image but not the support material.

6. The apparatus as set forth in claim 4 wherein said roller means are stainless steel and are adjustably mounted with respect to each other to apply between 50 and 200 pounds pressure per linear inch to the toner images and support material passed therebetween.

7. Fusing apparatus for a xerographic reproducing machine of the type wherein a support material is fed along a support material feed path from a supply station to a receiving station, a transfer means located along the support material feed path between the supply and receiving station whereat toner images are electrostatically transferred to the support materi- 6 al, said fusing apparatus including:

a pair of stainless steel rollers located on opposite sides of the support material sheet feed path between the transfer means and the receiving station said roller means extending generally transversely of said support material feed path and of such length as to partially fix the efiective toner image on said support material;

means to adjustably support said rollers so as to apply between 50 and 200 pounds pressure per linear inch to support material and toner images passed therebetween;

means to rotate said rollers at a speed equal to the linear speed of the support material passed therebetween;

a xenon flash tube located in a reflective cavity along the support material feed path between said rollers and said receiving station and adapted to emit radiant energy at a wavelength whereby it will be absorbed by toner images but not absorbed by support material moved therepast to complete the fix; and

brush means located along the support material feed path between said flash tube and said receiving means adapted to rotate and remove unfused tonerfrom the support material.

Claims

1. In a xerographic machine of the type wherein toner images are electrostatically held to a support material which is moved along a support material feed path through the machine, fixing means including: a radiant energy power source located along the support material feed path to fix the toner images to the support material moved therepast; and roller means located adjacent the support material feed path in advance of said radiant energy power source, said roller means providing at least 50 pounds pressure per linear inch and extending generally transversly of said support material feed path and of such length as to precompact the effective toner image on said support material.

4. A xerographic reproducing machine including means to electrostatically adhere a toner image to a support material, a receiving station to receive the support material with the toner image, means to move the support material along a support material feed path from said image-adhering means to said receiving station and fusing means located along the support material feed path, said fusing means including: a pair of rollers positioned on opposite sides of the support material feed path through which the support material must pass as it is moved to said receiving station said roller means providing at least 50 pounds pressure per linear inch and extending generally transversely of said support material feed path and of such length as to partially fix the effective toner image on said support material; means to rotate said rollers at a linear speed equal to that of the movement of the paper; and radiant fusing means positioned between said rollers and said receiving station to complete the fix of the toner image to the support material.

5. The apparatus as set forth in claim 4 wherein said radiant energy source is a xenon flash tube capable of emitting energy at a wavelength whereat it is absorbed by the toner image but not the support material.

7. Fusing apparatus for a xerographic reproducing machine of the type wherein a support material is fed along a support material feed path from a supply station to a receiving station, a transfer means located along the support material feed path between the supply and receiving station whereat toner images are electrostatically transferred to the support material, said fusing apparatus including: a pair of stainless steel rollers located on opposite sides of the support material sheet feed path between the transfer means and the receiving station said roller means extending generally transversely of said support material feed path and of such length as to partially fix the effective toner image on said support material; means to adjustably support said rollers so as to apply between 50 and 200 pounds pressure per linear inch to support material and toner images passed therebetween; means to rotate said rollers at a speed equal to the linear speed of the support material passed therebetween; a xenon flash tube located in a reflective cavity along the support material feed path between said rollers and said receiving station and adapted to emit radiant energy at a wavelength whereby it will be absorbed by toner images but not absorbed by support material moved therepast to complete the fix; and brush means located along the support material feed path between said flash tube and said receiving means adapted to rotate and remove unfused toner from the support material.