A method and an apparatus for fixing an image formed by a colorant upon an image support body is described. A fluid, binder material contacts a heated transport surface. The heated surface comprises an elastomeric material which is positioned on a tubular body formed of a material having a relatively high coefficient of thermal conductivity. The transport surface advances the heated binder material to a nip formed with an adjacent pressure contact surface which is transported in moving engagement with the heated surface. The binder material at the nip temperature exhibits a viscosity which exceeds the surface energy of the elastomeric transport surface while the surface energy of the support material and the imaged surface is greater than the surface energy of the elastomer. The binder is thus transferred to the imaged surface for fixing the image thereon.
This is a division, of application Ser. No. 556, 065, filed 03/06/75, now abandoned.
This invention relates to a method and an apparatus for fixing images on a support material. The invention relates more particularly to an improved method and apparatus for applying a binder material to an image bearing surface.
In various reproduction systems, an image formed on a support surface is generally fixed to the surface in order to inhibit smudging of the image and to assure its relative permanency. In the xerographic processing arts, for example, an electrostatic latent image is formed on a photoreceptor and is developed by contacting the photoreceptor with a developer material which includes a colorant. The developed image is then transferred to a support sheet for permanent recording. In general, slight contact with the image in this state will cause movement of the toner particles on the support sheet, smudging, and distortion of the image. Therefore, it is customary as a step in the reproduction process to bond or fix the image to the support sheet.
One widely employed technique for effecting this bonding is to provide a particulate toner material which comprises a mixture of a colorant and a resin which can be thermally or solvent softened. As thermal energy or solvent vapor is applied to the toner material in image configuration on the support sheet, the toner softens and tends to become fluid; the contact points between the developed image and the support sheet are broadened; and, the softened toner particles flow together and into the paper fibers. Fixing of the image is also at times enhanced by the simultaneous application of pressure to the support sheet. The softened image then sets upon removal of heat or solvent vapor to provide a relatively permanent image record.
At times it is not feasible to provide a developer material containing a fixing resin because of limitations imposed on the physical characteristics of the materials by the process or by the use of a process which cannot accommodate such a material. In the former case, for example, when the image is formed of pigment particles that are relatively stable with respect to the heat or solvents, then the component used to effect fixing must be introduced after the image is formed. This is also true when fixing resins are employed whose softening temperature or solubility is impractical to employ for the application at hand. An example of a process which provides a pigmented image and which is not generally adapted to accommodate a blend of a heat or vapor softenable resin with the pigment is the photoelectrophoresis process for reproducing images.
The simplest image-forming material is one in which the developer material consists of pure pigments. Typical pigments that have been used to form xerographic images are cadmium yellow, chrome yellow, pulvarized charcoal, and zinc oxide. However, most pigments have no physical property that can be utilized for causing them to adhere to a substrate such as paper. In those situations wherein a mixture of pigment and fixing agent cannot be employed, then fixing of the image has been provided subsequent to the imaging process by applying a fixing vehicle to the entire imaged surface. These techniques include aerosol spraying of the image support body with a clear acrylic; juxtopositioning a polyethylene coated sheet with respect to the support body and applying heat to the sandwich thereby causing the polyethylene to flow to the image support sheet and to fix the image to the support body; and, contacting the image support body with a gelatin capsule coated paper which is initially softened with water.
While these techniques are effective in providing the desired fixing, they do not lend themselves to a continous process for fixing images on a carrier or on a support body such as paper or other plastic film substrate. Furthermore, the pigments exhibit a tendency to stain bodies with which they come into contact. This staining characteristic is undesirable and is believed due to electrostatic particle transfer combined with surface forces associated with moisture and other wetting characteristics. As a result, apparatus components such as transfer rollers are stained and deleteriously affect subsequent images which are formed.
Accordingly, it is an object of this invention to provide an improved method and apparatus for fixing an image formed by a colorant on a support body.
Another object of the invention is to provide an improved method and apparatus for providing continuous fixing of images formed by a colorant.
In accordance with features of the method of this invention, a colorant image is fixed on a support material by heating a binder material to a fluid state, contacting a transport surface at a higher temperature with the binder material, transporting the heated surface and the supported binder material to a nip formed between the binder transport surface and an adjacent pressure contact surface which is transported in moving engagement with the binder transport surface, and transporting a substrate bearing a colorant image through the nip formed by contact beneath the surfaces whereby the binder material is deposited on the image support material and is fixed thereto.
In accordance with features of the apparatus of this invention, an apparatus for fixing an image to a sheet support material comprises a first body having an outer surface thereof, a layer of material formed on said outer surface, means for heating said body to a predetermined temperature, a second body having an outer surface thereof, a layer of material formed on said surface of said second body, said first and second bodies positioned for providing contact between surfaces of said layers at a nip formed therebetween, means for imparting motion to said bodies, and means for applying a binder material to said layer of said first body for transport to said nip whereby a surface of sheet material introduced to said nip is transported therethrough by the motion of said body and a surface thereof adjacent to said surface of said first body is coated with said binder material.
A fixing device having a rotatable heating member heated by a heat source, a rotatable pressure member for pressing against the rotatable heating member, a heat-moving member formed of material having excellent thermal conductivity characteristics and constructed so as to freely make contact with at least one rotatable member among the rotatable heating member and the rotatable pressure member, and a drive unit to move the heat-moving member between a contact position and retracted position relative to at least one of the heating member and the rotatable pressure member. The heat-moving member changes either heat capacity or thermal conductivity or both heat capacity and thermal conductivity relative to the axial direction of the rotatable heating member or the rotatable pressure member.
A toner image treatment device smoothing an irregular surface of a fixed toner image with coating a transparent auxiliary material by a coating roller. The coating roller has a layer of porous elastic material being impregnated with a transparent resin which is a solid at room temperature but is a liquid at a high temperature, and a heater provided inside the porous elastic material for melting the transparent resin.
Disclosed is a toner thermal fixing roller comprised of the following; a heating unit internally provided with a heating source: a roller pressed against said heating roller; and several member parts preventing reflective heat from heating the heating source, while these member parts are provided inside the bearing parts which are set to both ends of the heating source, the bearing parts being set to both ends of the heating roller and installed inside the hollow portion of the heating roller.
