US3900590A

US3900590A - Xerographic fusing apparatus

Info

Publication number: US3900590A
Application number: US459863A
Authority: US
Inventors: Prafulla S Dhoble
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1966-06-23
Filing date: 1974-04-11
Publication date: 1975-08-19
Anticipated expiration: 1992-08-19

Abstract

Method and apparatus to heat fix a heat fusible xerographic powder image to a final support material in which the powder image is first transferred to a final support material and the image-bearing support material then brought into contact with a bath of pure hot liquid metal for a period of time sufficient to fix the image to the support material. The temperature of the bath is maintained at a temperature high enough to fuse the image but below that at which the support material is damaged.

Description

United States Patent 1191 Dhoble 1 1 XEROGRAPHIC FUSING APPARATUS [75] Inventor: Praiulla S. Dhoble, Webster, NY. [73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Apr. 11, 1974 [21] Appl. No.: 459,863

Related U.S. Application Data 163] Continuation of Ser. No. 559,852. June 23, 1966,

abandoned.

{52] U.S. C1. 427/22; 427/24; 118/58, 118/637; 134/122; 165/104; 95/89; 219/216; 219/388; 219/439; 219/530; 432/8; 432/59 [58] Field 01 Search l17/17.5, 119.6, 119.8, 117/21; 118/58, 419, 428, 429, 637; 134/5, 105,122;432/8, 59; 219/216, 388, 439, 530;

[451 Aug. 19, 1975 3,103,153 10/1963 Limberger 117/37 LE 3,202,526 8/1965 Ostensen 117/37 LE 3,256,002 6/1966 Hudson 1l7/17.S 3,336,906 8/1967 Michalchik 117/37 LE 3.515.855 ll/1968 Mix 219/388 3,567,484 3/1971 White et a1. [17/1198 3,706.588 12/1972 Shimola 117/21 3.788.873 1/1974 Detig [17/1198 FOREIGN PATENTS OR APPLICATIONS 951,391 3/1964 United Kingdom 117/1 19.6 22.982 10/1912 United Kingdom 117/1 19.6 149,849 9/1950 Australia 117/1 19.6 800,122 8/1958 United Kingdom 117/1 19.6

Primary Examiner-Michael Sofocleous Attorney, Agem, 0r Firm-Robert .1. Bird [57} ABSTRACT Method and apparatus to heat fix a heat fusible xerographic powder image to a final support material in which the powder image is first transferred to a final support material and the image-bearing support material then brought into contact with a bath of pure hot liquid metal for a period of time sufficient to fix the image to the support material. The temperature of the bath is maintained at a temperature high enough to fuse the image but below that at which the support material is damaged.

15 Claims, 5 Drawing Figures PATENTEDAUG 1 9|975 INVENTOR.

n ,2 :24, A r TORNE rs PRAFULLA s. DHOBLE B M;

PATENTED AUG] 9 I975 FIG 3 INVENTOR. PRAFULLA S. DHOBLE PATENTEB AUG 1 91975 SLZZU 3 BF 3 FIG. 5

INVENTOR. PRAFULLA S. DHOBLE BY 9 Q ATTORNEYS XEROGRAPl-IIC FUSING APPARATUS This is a continuation of application Ser. No. 559,852, filed June 23, 1966 and now abandoned.

This invention relates to xerographic image fusing and, in particular, to apparatus and method for effecting image fixing by placing an image bearing support material in thermal contact with a bath of liquid metal.

In the process of xerography as disclosed in the Carlson US. Pat. No. 2,297,691, issued Oct. 6, I942, a xerographic plate comprising a layer of photoconductive insulating material placed on a conductive backing is given a uniform electric charge over its surface. The charged photoconductor is then exposed to a light image of the subject matter to be reproduced thereby discharging the photoconductive plate in the areas of greatest radiation intensity to create an electrostatic latent image. The latent image is developed with an electrostatically charged finely divided powder, herein referred to as xerographic toner, which is brought into contact with the photoconductive layer. The toner is electrostatically attracted to the image areas thus developing the latent image. Thereafter, the developed xerographic powder image is electrostatically transferred to a support material to which it is fixed to form a permanent copy.

In the xerographic process, a variety of powder developing materials can be employed to develop the latent image. lt has been found preferable, however, to develop images with a toner made from pigmented resins developed specifically for use in the xerographic process. Such resins have been developed to produce dense images of high resolution having good graphic reproduction qualities as well as having characteristics which permit convenient handling and storage.

The three most prevalent types of xerographic fusing in commercial use today are heat fusing, vapor fusing, and a combination of pressure and heat fusing. Because of its simplicity and flexibility of application, heat fusing has received the widest commercial usage of the three. in order to heat fuse powder images formed of powder resins, it is necessary to heat the powder and the support material to a relatively high temperature. It is undesirable, however, to raise the temperature of the support material to a temperature at which it is damaged or discolored.

The method most generally employed to heat fix a xerographic powder image has been the process of radiant heat fusing. Such a radiant heat fuser is disclosed by Eichler in US. Pat. No. 2,965,868. in radiant heat fusing, the toner image is exposed to high intensity radiant heat energy for a period of time sufficient to plasticize or fuse the toner to the support material. In most applications the radiant heat source is suspended above the image bearing support material and the radiant heat energy concentrated thereon by means of reflectors or the like. The radiant heat energy must, therefore, travel through a medium of ambient air before reaching the surface to be heated.

It is well known in infrared spectroscopy that carbon dioxide has a remarkable ability of absorbing maximum amounts of infrared radiation which are present at wavelengths of about 3.0 and 4.3 microns. Similarly, water vapor will absorb infrared radiation at numerous wavelengths between 4.0 and 7.0 microns. it should be noted that both water vapor and carbon dioxide are found in ambient air. These wavelengths at which water vapor and carbon dioxide absorb maximum infrared energy fall within a band of wavelengths at which most efficient infrared radiant energy sources propagate heat energy (1.0 to 7.0 microns).

It is obvious that ambient air conditions will vary from day to day. For example, the humidity content in the air, unless controlled by costly air conditioning systems, will vary with changes in weather conditions. Likewise, carbon dioxide, which is a waste gas produced by automobile and many industrial processes, is found in varying amounts in the ambient air, the exact content also being dependent upon certain weather conditions as well as other phenomena. An extreme example of this latter principle of course being the smog" conditions which prevail about certain industrial centers. As can be seen, radiant heat energy which must travel through a medium of ambient air will lose some of this energy before reaching the material to be heated. Therefore, a radiant heat fuser having an ambient air gap between the source and the copy material will produce copy which, although commercially acceptable, varies as to fusing from day to day.

It is also widely known that the most efficient sources of radiant heat energy are bodies which emit energy at very high temperatures, the efficiency of the source being directly proportional to its operating temperature. Further, high efficiency sources produce infrared energy which is concentrated within a very narrow band of wavelengths, the energy so produced being semi-monochromatic in form.

The most efficient fusing of xerographic copy is produced when the support material and the toner are both rapidly raised to the same temperature, this temperature being above the fusing temperature of the toner but below that at which the support material is damaged or discolored. However, when a high temperature infrared source is used to fuse xerographic copy, this temperature balance between toner and support cannot be maintained because the high temperature infrared energy is concentrating in a band of wavelengths which favors one material, generally the toner, over the other. Selective infrared fusing in which xerographic toner is heated in preference to the paper has been commercially utilized but it has been found that images of low toner density cannot be fused by this method because the intensity of the energy is so high the support material becomes damaged before complete fusing of low density images is obtained.

it is therefore an object of this invention to improve method and apparatus for heat fixing a heat fusable powder to a support material.

It is a further object of this invention to control positively and accurately the temperature of the xerographic toner and the support material during heat fusing operations.

It is a still further object of this invention to provide method and apparatus to heat fuse a xerographic image uniformly within a medium that is self-contained and impervious to changes in ambient air conditions.

Another object of this invention is to efficiently and rapidly heat fuse areas of low toner concentration without causing injury to the support material.

Yet another object of this invention is to rapidly heat fuse a xerographic image in an economic and efficient manner.

These and other objects of this invention are achieved by placing a support material upon which is loosely adhered a powder toned xerographic image in thermal contact with a hot bath of relatively pure liquid metal, the metal being at a temperature sufficient to fuse the powder image but below the temperature at which the support material will be damaged.

For a better understanding of this invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. I is a schematic representation of a xerographic machine incorporating the fusing apparatus of this invention;

FIG. 2 is a side view of the fusing apparatus of the machine shown in FIG. 1 and embodying the present invention;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 44 in FIG. 3;

FIG. 5 is a side elevational view of an alternative embodiment of the fusing apparatus found in the present invention.

In the present invention there is provided a bath of hot liquid metal contained within an insulated housing; the bath being utilized as a heat source to supply the energy required to heat fix a xerographic image. Although liquids are generally considered poor thermal conductors, the liquids of some metals such as lead, bismuth, and mercury, for example. all evidence relatively good thermal conductivity and have good heat transfer characteristics.

It should also be noted that the liquid metals having good heat transfer properties are also the heavy, nonwetting metals. It has been found that a bath as utilized in the present invention can be uniformly brought to operating conditions thus providing a heat source which can be thermally controlled. A uniform temperature can be maintained in the bath for three reasons: l the bath is contained within an insulated housing so that heat leaving the system is minimized, (2) the bath is not in motion and therefore no heat losses due to forced convection or the like are present, and (3) the heavy liquid gives up very little of its internal energy because of the interaction of the molecules.

Liquid metals have the unique property of not readily mixing or bonding with other materials. For example, liquid mercury which is placed upon a piece of paper can be rolled thereon freely without wetting the paper. Likewise, a xerographic image loosely adhered to a paper support material may be brought through or over a bath of pure liquid metal without the metal wetting the paper support or the toner.

In the preferred embodiment of the present invention, a toner image bearing support material is immersed in a bath of hot liquid metals so that the hot liquid is brought into absolute contact with the entire surface area of both the toner and the support material regardless of the variance in the surface contours, a feat heretofore unobtainable in xerographic heat fusing. A metal is utilized in the bath which has a relatively high specific heat so that once the bath is brought to operating temperature the heat energy contained in the bath will be held therein rather than being rejected from the system. Because of the relatively high specific heat of the bath material and the uniformity with which the bath material may be heated, it is possible to accurately control the amount of energy delivered to the material to be heated which is placed in absolute contact with the bath.

Although it forms no part of the subject invention, there is shown schematically in FIG. 1 a continuous xerographic apparatus for the purpose of illustrating a suitable environment for a liquid metal heat fuser of the subject invention.

As shown in FIG. 1, the xerographic apparatus comprises a photoconductive layer of light-receiving surface on a conductive backing and formed in the shape of a drum, generally designated by numeral 10, which is mounted on a shaft II journaled in a frame (not shown) to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of xerographic processing stations. Drum 10 is rotated at a constant rate through the drive action of synchronous motor 12.

For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the drum surface may be described functionally, as follows:

A charging station, at which a uniform electrostatic charge is deposited on the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof and thereby form a latent electrostatic image of the copy to be reproduced;

A transfer station, at which the xerographic powder image is electros'tatically transferred from the drum surface to a transfer material or support surface; and,

A drum cleaning and discharge station, at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge thereon.

In general, the charging apparatus 13, which may be of the type disclosed in Walkup US. Pat. No. 2,777,957, includes a corona discharge array of one or more corona discharge electrodes that extend transversely across the drum surface and are energized from a high potential source and are substantially enclosed within a shielding member.

Next subsequent thereto in the path of motion of the xerographic drum is an exposure station. This exposure station may be one of a number of types of mechanisms or member such as desirably an optical projection system 14 or the like designed to project a line copy image onto the photoconductive surface of the xerographic drum from an original as is well known in the art.

Adjacent to the exposure station is a developing station in which there is positioned a developer housing 15 including a lower or sump portion for accumulating developing material 16. A bucket type conveyor I? having a suitable driving means, such as motor I8, is used to carry the developing material to the upper part of the developer housing where it is cascaded down over a hopper chute 21 onto the xerographic drum.

As the developing material is cascaded over the xerographic drum, toner particles are pulled away from the carrier component of the developing material and deposited on the drum to form powder images, while the partially denuded carrier particles pass off the drum into the developer housing sump. As toner powder images are formed. additional toner particles must be supplied to the developing material in proportion to the amount of toner deposited on the drum. For this pur pose there is provided a container 22 for the toner 23 to be added to the developing material as needed, the toner being added at a rate determined by control gate 24.

After development, the image thus formed is transferred to support surface web 25, which may be of paper or any other suitable material. Web 25 is continuously transported from supply spool 26 to take-up spool 27 by paper handling apparatus 28, which may be of a type disclosed in Crumrine et al. US. Pat. No. 2,781,705. Paper handling mechanism 28 includes a synchronous motor 3] driving take-up spool 27 and drive rolls 32, while guide rolls 33 and 34 serve to direct web 25 into contact against a powder image on the surface of drum l0. Electrostatic transfer unit 35, which may be of a type similar to unit 13, generates an electrostatic charge to electrostatically attract the powder image from the surface of drum to web 25.

Thereafter, image-bearing web is transported through fuser 40 of the type, hereinafter described in detail, whereby the developed and transferred xerographic powder image on the web 25 is permanently fixed thereto.

The next and final station in the device is a drum cleaning and discharge station where any powder remaining on the xerographic drum after transfer is removed by rotating brushes and the xerographic drum is flooded with light to cause dissipation of any residual electrical charge remaining on the xerographic drum. Thus, the residual powder image on the surface of drum 10 after transfer is removed by brushes 36 driven by motor 37 after which residual electrostatic charge is dissipated by illumination from lamp 38.

Referring now to FIGS. 24, inclusive, there is shown a preferred embodiment of the liquid metal fusing device 40 constructed in accordance with the present invention. In this preferred embodiment, the fusing device includes the housing 41 upon which is mounted cover 42. The housing and cover are constructed of an outer shell 43 and an inner shell 44 between which is located insulating material 45 so that heat generated within the fusing apparatus is contained therein.

A predetermined amount of metal is placed within the housing so that a desired level line is maintained when the metal is liquified. There are commercially available metals and alloys having low melting temperatures capable of being used in the present invention, however, it has been found that alloys of bismuth, lead, and antimony, which have very low melting temperatures l l 7F 360F) are preferable as a bath material. Such bismuth based alloys are sold commercially by the Cerro Company of Cleveland, Ohio, under various trade names.

Heat fusing is produced in the present invention by placing a heat fusable powder image bearing support material 25 in thermal contact with a bath of hot liquid metal 46 for a period of time sufficient to heat fix the toner image to the support material. Because of the intimate contact between the hot liquid metal and the material to be heated, sufficient heat is transferred to fuse the toner image rapidly and efficiently. It has been found that pure liquid metal, that is, a metal containing little or no impurities, has the quality of not readily bonding or mixing with other materials and, therefore, a toned image bearing support material may be brought through a bath of hot liquid metal without the metal wetting either the toner or the support material.

Located in the bottom of housing 41 are a series of heating units 85 comprising tubular members 87 in which are placed resistance wires 86. The heating units, which are connected to any suitable source of electrical power (not shown), are electrically energized so that the temperature within the housing is raised to a level sufficient to liquify the metal contained therein. Because of the time required to bring a liquid metal bath to operating temperatures, it is advantageous to provide extra heating elements, or heating elements capable of being electrically overloaded, so that sufficient heat can be transferred to metal 46 to bring the bath rapidly to an operating temperature. Further circuitry can be provided (not shown) to maintain the fuser in a standby condition when the automatic xerographic equipment is not in use thereby avoiding long warm-up periods.

Thermostat 88 (FIG. 4) is electrically connected to the heating units so that a desired bath temperature can be maintained and closely controlled within a very narrow temperature range. For example, in order to fuse resinous powder images formed of toner most commonly used in the xerographic process, it is necessary for the toner to be placed at a temperature of approximately 240F. However, when a support material of paper is used, it is undesirable to raise the temperature of the paper support material higher than approximately 380F because at these elevated temperatures the support material will become rapidly discolored. Heretofore, in most known xerographic heat fusing processes, a temperature control of this nature was difficult to maintain because of many variables such as ambient air conditions which were present over which there was no control. However, in the present invention a temperature spread of a very few degrees may be accurately maintained with little or no difficulty by means of a thermostatic control.

As shown in the preferred embodiment, both lower entrance roll 52 and lower exit roll 59 are mounted on

shafts

55 and 57, respectively, which extends through the housing and are journaled in bearings 62 and mounted in bearing brackets 60. Similarly, upper entrance roll 51 and upper exit roll 58, which are mounted on

shafts

54 and 56, respectively, are mounted in an adjustable bearing brackets 60. The bearings brackets are adjustably affixed to the housing and secured thereto by means of screws 61 so that the upper and lower rolls may be adjusted to grip in friction driving contact a support material inserted therebetween. A hearing bracket gasket 63, fabricated of silicone rubber, is provided between the bearing bracket and the housing to prevent leakage of liquid metal. The upper entrance and exit rolls are driven in synchronization with the bottom driving rolls by means of gears 74 (FIG. 3) fixed to the left outboard end of the shafts.

immersing roll affixed to shaft 69 is similarly journaled in bearing 62 mounted in adjustable bearing brackets 60.

The lower entrance and lower exit drive shaft extend through the housing and have affixed thereto drive pulley 83. To facilitate proper passage of the support materials through the fuser,

housing pulleys

82 and 83 are properly sized so that the exit and entrance rolls are driven at the same peripheral speed as immersing roll 70.

Pulleys

82 and 85 are operutively connected to motor 31 (FIG. I) by means of belt 75.

Alloys of bismuth, lead. and antimony have a high specific gravity (8.2 to 10.3) and, therefore, materials such as paper and toner having a lower specific gravity will be buoyant in a bath of these metals. lrnmersing roll 70 (FIG. 4) is provided to place the toned image below the surface of the hot liquid metal so that both thermal and physical contact is maintained between the two. As the support material is being driven forward by the entrance rolls, it is guided into the immersing roll by means of a series of guide wires 71 supported on pin 73 mounted in the housing. The guide wire assures that the support material will contact the positively driven immersing roll at some point below the center line causing the support material to be driven under the surface of the hot liquid metal. Because roll 70 is partially immersed below the predetermined level line, liquid metal will be displaced causing an opposite force to be exerted on the support driven thereunder equal to the amount of metal displaced by the roll. This equal and opposite force (buoyant force) will tend to hold the support material to the immersing roll as it is carried through the hot liquid metal bath.

It should be noted, that in this preferred embodiment, the xerographic copy is transported through the fuser housing image side down so that the image area will come into direct contact with the hot metal. Although the buoyant forces are such to hold the support to the immersing roll, these forces are insufficient to disturb the toner as it is propelled through the bath.

Heat transfer can be compared to electrical flow in that the less resistance placed between the source of energy and the body receiving the energy, the greater will be the amount of energy reaching the receiving body. By immersing the toner and support material in a bath of hot liquid metal, the thermal resistance between the heat source and the receiver will be minimized to produce a rapid and efficient heat transfer.

Upon leaving the immersing roll, support material 25 will float to the surface of the bath while continuing to be driven forward by the combined action of the entrance drive rolls and the immersing roll. The support material is guided into contact with exit rolls 58 and 59, respectively, by means of a series of guide wires 71 sup ported on pins 73. A series of pickup wires 76 (FIG. 4) suspended in a liquid metal on pin 73, act in cooperation with guide wires 71 to properly align the support material in the exit rolls. On leaving the exit rolls the support material is guided out of the housing through exit 48 by means of exit guide plate 64.

It has been found that the buoyant forces exerted on the xerographic toned image, due to the amount of metal displaced by roll 70, aid in the xerographic fusing process. Although this phenomena is not fully understood, it is felt that by forcing the hot liquid metal into intimate Contact with the surface of the xerographically toned image the rate of heat transferred is increased.

Pure liquid metal has a corrosive effect when placed in contact with other metals, therefore, it is necessary to provide a protective covering on the exposed metal parts on the interior of housing 41. Once all the parts have been assembled in place. the inside of the housing is covered with a protective coating of form-retaining wax-like synthetic having a high melting point. Among such synthetics are: polytetrafiuoroethylene which is sold commercially by the E. l. DuPont de Nemours Company under the trade name Teflon", and polytrifluorochloroethylene which is sold commercially by the M. W. Kellogg Company under the trade name Kel- F Although this preferred embodiment describes the liquid metal fusing process in reference to a web support material. it should be obvious to one skilled in the art that the fuser can be easily adapted to process support material in the form of cut sheets as well as a web.

Slag, which is produced in liquid metals by the oxides of impurities found therein, will bond with the powder image during fusing to give the xerographic toner a slightly metallic luster. Although the bath is to be charged with a pure metal having little or no impurities, it is quite possible that some impurities will be carried on the support material into the bath over a long period of time. it should be noted that this slag build up will in no way effect the fusing properties of the present invention, however, a slightly metallic luster on the finished xerographic copy may in some cases be commercially undesirable.

FIG. 5 is an embodiment of the present invention in which the support material is floated across rather than immersed below the surface of the bath so that the toner does not come in contact with the hot liquid metal. Sufficient heat is transferred by means of convection and conduction through the support material to produce the desired heat fusing. Support material 25 is introduced into the fuser housing through opening and guided into entrance drive rolls 91 and 92 by means of guide plate 93.

Guide wires

89 and 94, located within the housing so as not to disturb the image areas. direct the support material, which is being transported across the surface of the hot liquid metal with the image side up, into contact with exit guide rolls 98 and 99. The exit drive rolls 98 and 99 then expel the support material from the housing through means of exit 97. It should be obvious to one skilled in the art that the rate of travel of the support material through the fuser can be controlled so that sufficient time is allowed for heat to be transferred through the support material to properly fuse the toner to the support.

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

What is claimed is:

1. Apparatus to heat fix a xerographic toner powder image to a final support material including means to place a toner powder image on a final support material, means to immerse the image bearing support material in a bath of liquid metal such that the metal exerts a pressure on the toner image to support the toner in image configuration, and

means to maintain the temperature of the liquid metal at a level sufficient to uniformly heat the toner powder image to the image fixing temperature and below the temperature at which the support material is damaged.

2. Apparatus to heat fix a toner powder image to a final support material including a housing being adapted to contain a quantity of liquid material,

a bath of hot liquid metal supported in said container,

said metal having a high specific gravity,

drive means associated with said housing and being arranged to move an image bearing support material through said housing,

an immersing roll positioned in said housing with at least a portion of said roll being supported below the surface of the liquid bath,

means to rotate said immersing roll at a peripheral speed equal to the speed at which the image bearing support material is being moved through said housing, and

guide member to direct the image bearing support material under said immersing roll such that the hot liquid metal exerts a pressure over the entire surface of said toner image wherein the toner powder image is uniformly heated to the fusing temperature by the hot liquid metal in pressure contact therewith.

3. A method of heat fixing a heat fusible toner image to a final support material includin electrosta ifalw'fita'w jatfidr 'iiii'a (:"dn llt'fmal -sup";-

port material wherein toner particles are loosely bonded to said support surface in a raised image configuration,

providing a bath of hot highly dense liquid metal,

maintaining said bath at a temperature at which the toner image is fixed and below a temperature at which the support material is damaged,

moving said image bearing support material below the surface of said bath wherein the dense hot metal exerts a pressure over the entire surface of said image to uniformly heat said image to the fusing temperature.

4. The method of claim 3 wherein said bath is maintained at a temperature between 240F. and 360F.

5. A fusing apparatus for fixing a xerographic image of thermo-responsive powder located on a support member comprising a heat exchange portion having a heat storage and transfer medium, said medium further comprising a heated liquid which is nonwetting to the support member and the image, said liquid heated to a temperature greater than the fusing temperature of the thermo-responsive powder and less than the scorch point of the support member,

container means for containing said liquid,

heating means for heating said liquid,

conveying means for conveying the support member with the xerographic powder image thereon through said heat exchange portion, whereby the xerographic powder images are fixed by heat transfer from said heat storage and transfer medium to the support member and the powder images.

6. The apparatus of claim 5 wherein said nonwetting liquid is a molten metallic alloy.

7. The apparatus of claim 5 wherein said heating means includes control means for maintaining said temperature of said liquid within said temperature range.

8. A fusing apparatus for fixing a xerographic image of thermo-responsive powder located on a support member comprising:

a heat storage and transfer medium for storing heat energy and for transferring heat energy to the support member having the xerographic powder image thereon, said medium being a heated liquid that is non-wetting to the support member and the powder image, said liquid heated to a temperature greater than the fusing temperature of the thermo-responsive powder and less than the scorch point of the support member;

container means for containing said liquid;

conveying means for conveying the support member across and in contact with the surface of said heat storage and transfer medium; and

heat supply means for supplying heat energy to said nonwetting liquid, said nonwetting liquid retaining said heat energy as heat energy, wherein heat transfer from said nonwetting liquid to the support member and the powder image fixes the powder image.

9. The apparatus of claim 8 wherein said nonwetting liquid is a molten metallic alloy.

10. The apparatus of claim 9 including means for positioning said nonwetting liquid for contacting said supp'ortniember to provide heat to said support member, as it passes across said heat storage and transfer medium.

11. The apparatus of claim 9 including means positioning the support member and said molten metallic alloy to be in contact with each other, thereby effecting heat transfer to the support member.

12. The apparatus of claim 10 wherein said positioning means is a revolving cylinder partially submerged in said molten alloy.

13. The apparatus of claim 8 wherein said heat supplying means further comprises control means to maintain said non-wetting liquid within said temperature range.

14. A fusing apparatus for fixing a xerographic image of thermo-responsive powder located on a support member comprising a heat exchange portion having a heat storage and transfer medium, said medium comprising a heated liquid which is nonwetting to the support member and the image, said liquid heated to a temperature greater than the fusing temperature of the thermoresponsive powder and less than the scorch point of the support member,

container means for containing said liquid,

heating means for heating said liquid,

conveying means for conveying the support r mber with the xerographic powder image there into contact with said heat transfer and storage medium, whereby the xerographic powder images ar fixed by heat transfer from said heat storage and transfer medium to the support member and the powder image.

15. in the process of making an electrostatically produced copy wherein thermo-responsive particulate material is arranged in a predetermined pattern on a support member, the improvement comprising contacting the support member with a body of liquid sufficient in size and heat content to effect a thermal fixing of said thermo-responsive particulate material without degrading said support member or said thermo-responsive particulate material, and maintaining said contact for a time sufficient to thermally fix said thermoresponsive material to said support member.

Claims

1. APPARATUS TO HEAT FIX A XEROGRAPHIC TONER POWDER IMAGE TO A FINAL SUPPORT MATERIAL INCLUDING MEANS TO PLACE A TONER POWDER IMAGE ON A FINAL SUPPORT MATERIAL, MEANS TO IMMERSE THE IMAGE BEARING SUPPORT MATERIAL IN A BATH OF LIQUID METAL SUCH THAT THE METAL EXERTS A PRESSURE ON THE TONER IMAGE TO SUPPORT THE TONER IN IMAGE CONFIGURATION, AND MEANS TO MAINTAIN THE TEMPERATURE OF THE LIQUID METAL AT A LEVEL SUFFICIENT TO UNIFORMLY HEAT THE TONER POWDER IMAGE TO THE IMAGE FIXING TEMPERATURE AND BELOW THE TEMPERATURE AT WHICH THE SUPPORT MATERIAL IS DAMAGED.

2. Apparatus to heat fix a toner powder image to a final support material including a housing being adapted to contain a quantity of liquid material, a bath of hot liquid metal supported in said container, said metal having a high specific gravity, drive means associated with said housing and being arranged to move an image bearing support material through said housing, an immersing roll positioned in said housing with at least a portion of said roll being supported below the surface of the liquid bath, means to rotate said immersing roll at a peripheral speed equal to the speed at which the image bearing support material is being moved through said housing, and a guide member to direct the image bearing support material under said immersing roll such that the hot liquid metal exerts a pressure over the entire surface of said toner image wherein the toner powder image is uniformly heated to the fusing temperature by the hot liquid metal in pressure contact therewith.

3. A METHOD OF HEAT FIXING A HEAT FUSIBLE TONER IMAGE TO A FINAL SUPPORT MATERIAL INCLUDING ELECTROSTICALLY PLACING A TONER IMAGE ON THE FINAL SUPPORT MATERIAL WHEREIN TONER PARTICLES ARE LOOSELY BONDED TO SAID SUPPORT SURFACE IN A RAISED IMAGE CONFIGURATION, PROVIDING A BATH OF HOT HIGHLY DENSE LIQUID METAL, MAINTAINING SAID BATH AT A TEMPERATURE AT WHICH THE TONER IMAGE IS FIXED AND BELOW A TEMPERATURE AT WHICH THE SUPPORT MATERIAL IS DAMAGED, MOVING SAID IMAGE BEARING SUPPORT MATERIAL BELOW THE SURFACE OF SAID BATH WHEREIN THE DENSE HOT METAL EXERTS A PRESSURE

4. The method of claim 3 wherein said bath is maintained at a temperature between 240*F. and 360*F.

5. A fusing apparatus for fixing a xerographic image of thermo-responsive powder located on a support member comprising a heat exchange portion having a heat storage and transfer medium, said medium further comprising a heated liquid which is nonwetting to the support member and the image, said liquid heated to a temperature greater than the fusing temperature of the thermo-responsive powder and less than the scorch point of the support member, container means for containing said liquid, heating means for heating said liquid, conveying means for conveying the support member with the xerographic powder image thereon through said heat exchange portion, whereby the xerographic powder images are fixed by heat transfer from said heat storage and transfer medium to the support member and the powder images.

8. A fusing apparatus for fixing a xerographic imAge of thermo-responsive powder located on a support member comprising: a heat storage and transfer medium for storing heat energy and for transferring heat energy to the support member having the xerographic powder image thereon, said medium being a heated liquid that is non-wetting to the support member and the powder image, said liquid heated to a temperature greater than the fusing temperature of the thermo-responsive powder and less than the scorch point of the support member; container means for containing said liquid; conveying means for conveying the support member across and in contact with the surface of said heat storage and transfer medium; and heat supply means for supplying heat energy to said nonwetting liquid, said nonwetting liquid retaining said heat energy as heat energy, wherein heat transfer from said nonwetting liquid to the support member and the powder image fixes the powder image.

10. The apparatus of claim 9 including means for positioning said nonwetting liquid for contacting said support member to provide heat to said support member, as it passes across said heat storage and transfer medium.

14. A fusing apparatus for fixing a xerographic image of thermo-responsive powder located on a support member comprising a heat exchange portion having a heat storage and transfer medium, said medium comprising a heated liquid which is nonwetting to the support member and the image, said liquid heated to a temperature greater than the fusing temperature of the thermo-responsive powder and less than the scorch point of the support member, container means for containing said liquid, heating means for heating said liquid, conveying means for conveying the support member with the xerographic powder image thereon into contact with said heat transfer and storage medium, whereby the xerographic powder images are fixed by heat transfer from said heat storage and transfer medium to the support member and the powder image.

15. IN THE PROCESS OF MAKING AN ELECTROSTATICALLY PRODUCED COPY WHEREIN THERMO-RESPONSIVE PARTICULATE MATERIAL IS ARRANGED IN A PREDETERMINED PATTERN ON A SUPPORT MEMBER, THE IMPROVEMENT COMPRISING CONTACTING THE SUPPORT MEMBER WITH A BODY OF LIQUID SUFFICIENT IN SIZE AND HEAT CONTENT TO EFFECT A THERMAL FIXING OF SAID THERMO-RESPONSIVE PARTICULATE MATERIAL WITHOUT DEGRADING SAID SUPPORT MEMBER OR SAID THERMORESPONSIVE PARTICULATE MATERIAL, AND MAINTAINING SAID CONTACT FOR A TIME SUFFICIENT TO THERMALLY FIX SAID THERMO-RESPONSIVE MATERIAL TO SAID SUPPORT MEMBER.