US3320060A - Deformation image reproduction process utilizing a voltage threshold reducing surfactant - Google Patents

Description

P w A 2 a n m, m m a w. L. GOFFE DEFORMATION IMAGE REPRODUCTION PROCESS UTILIZING A VOLTAGE THRESHOLD REDUCING SURFACTANT Filed Nov. 29, 1963 May 16, 1967 WILLI KYA L TE CSFFE w Q&

FIG. 5

A 7' TORNE Y United States Patent 3,320,060 DEFCRMATEQN IMAGE REHEGDUCTHGN PRUC- ESS UTILHZING A VCLTAGE THRESHOLD RE- DUCING SURFACTANT William L. Golfe, Webster, N .Y., assignor to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed Nov. 29, 1963, Ser. No. 326,831 22 Claims. (Cl. 96--1.1)

This invention relates to deformation imaging and in particular to frost deformation.

The usual ways of electrostatically deforming a deformable surface in accordance with an image pattern have required some means of depositing electrostatic charge selectively. The two most common ways of doing this have been to use a photo-conductive insulating layer in order to selectively control the movement of electrical charges in accordance with a light pattern, or else to use a direct means of selectively depositing the electric charge as with an electron beam or by charging through a stencil.

In accordance with the present invention, it has been discovered that selectively treating a deformable surface with appropriate surfactants will produce selective deformation in accordance with the deposition of such agents when the deformable material is uniformly electrostatically charged. This has been found particularly true in the case of frost deformation of the type disclosed in US. patent application, Ser. No. 193,277, filed May 8, 1962. As described in that application and as used herein, the term frost generally describes a random minute wrinkling produced by electrostatic charge on a soft insulating thermoplastic layer. Thus, it is an object of the present invention to define a method of deformation imaging in which the latent image comprises a surfactant.

It is an additional object to define a vapor thermographic process of deformation imaging.

It is an additional object to define method and means for forming a deformation image from a developed, transferred, xerographic image.

It is still a further object to define means for forming a frost image by selective deposition of a surfactant. Further objects and features of the invention will become apparent while reading the following description in connection with the drawings wherein:

FIG. 1 is a diagrammatic illustration of forming a latent image with a surfactant and a stencil;

FIG. 2 is a diagrammatic illustration of development of an image made in accordance with the present invention;

FIG. 3 is a diagrammatic illustration showing a selective deposition of a surfactant by vapor thermograph;

FIG. 4 is a diagrammatic illustration of fingerprinting in accordance with the present invention;

FIG. 5 is a diagrammatic illustration of means for continuously forming images in accordance with the present invention using vapor thermograph; and,

FIG. 6 is a diagrammatic illustration of means to form images in accordance with the present invention using xerography.

A frostable material generally exhibits a threshold, related to both electrostatic charge and temperature, at which frost deformation will begin to develop. This threshold, it has been found, can be made to vary by contamination of the surface by materials having the characteristics of surfactants. As used herein, the term surfactant denotes a substance for modifying the properties of a liquid medium at an interface by raising or lowering interfacial tension.

It was found, for example, that a thin film of Dow- 3,32%,966 Patented May 16, l 967 Corning D0200 silicone oil of 50 centistoke viscosity will drop the voltage threshold for frost development by 50%. Accordingly, the present invention concerns this effect and various means of utilizing it to form image-s. Thus, in FIG. 1, image-forming member 10 is illustrated as comprising conductive substrate 11 such as aluminum or other metal and deformable material 12 coated over substrate 11 in contact with the conductive surface. Substrate 11 can also be a transparent glass or plastic with a conductive coating either transparent, such as made with stannic oxide, or opaque as with an opaque thickness of evaporated metal. Suitable deformable materials are:

TAB LE I Trade N ame Chemical Type Manufacturer (1) Piccotex Pennsylvania Industrial Chemicals (2) Piccolyte Do. (3) Stayoelite 5 Hercules Power Co. (4) Staybelite 10 Do. (5) Piecoumaron Coumarone Pennsylvania gndustrial Chemicals 0. (6) Piccolastic D150". Styrene Do.

(7) Piccoflex A Polyvinyl chlorlde The thickness of the substrate is not important, but the resistivity of the substrate, at least that portion of it adjacent to the deformable material, must be less than 10 ohm-cm. and is preferably less than 10 ohm-cm. The deformable material should preferably have a thickness between /2 micron to 6 microns. Thinner layers give better resolution While thicker layers enable greater image density. One means of forming an image on this member is illustrated in FIG. 1 as positioning a stencil 13 against the surface of deformable material 12 and then applying a surfactant through the stencil. Any conventional type of stencil that will permit passage of the surfactant in the image areas may be used. The surfactant may be applied by means of an atomizer 15 as illustrated, or by means of a brush roller or any other device capable of applying the surface active material through the stencil. In one preferred embodiment, for example, deformable material 12 is a 2 micron layer of glyceral ester of abietic acid in which the abietic acid has been approximately 50% hydrogenated. This deformable material is sold under the name Staybelite 10 as listed above. The deformable material is thinned with a volatile solvent such as methyl ethyl ketone to a suitable coating consistency and then the substrate is dip coated at a speed to give the desired coating thickness. The surfactant for lowering the voltage threshold for frosting must readily wet the deformable material and should have a lower viscosity so as to lower the surface tension at the interface between the deformable material and the surfactant. An exemplary surfactant for use with Staybel-ite ester 10 is dimethyl polysiloxane (Dow-Corning DCZOO silicone oil) having a viscosity of 50 centistokes. The stencil is then removed from the image forming member and the deformation image is developed as illustrated in FIG. 2.

Particularly in a process such as that described above in Which the surfactant is applied mechanically or by a pray, the thickness of the surfactant layer may raise roblems. A low viscosity material such as 50 centistoke ilicone oil will flow readily and tend to fill the depresions of the deformation image. While the image is still isible with the depressions completely filled in, the conrast is greatly reduced since the refractive index differnce between the deformable material and the surfactant not as great as between the surfactant and air. Thus, t is preferable that the surfactant be applied in layers hat are thinner than the deformation depth of the frost mages, so that the surfactant surface follows the deformaions. Since the deformation depth is limited by the hickness of the deformable material, the surfactant layer hould be no thicker than one half micron and substanially thinner than the thickness of the deformable maerial. Alternatively, a thick surfactant can be washed if after forming the frost image.

FIG. 2 illustrates image forming member positioned vith its substrate against heating means 16. While this [eating means is illustrated as a hot-plate type of device :ontaining an electrical resistance heating element, other neans for heating image forming member 10 to frost emperature can be used. Thus, the entire member may e placed in an oven or heat may be directed at the deormable material by the use of heat lamps or the like. A :orona discharge device 17 is used to apply an electrotatic charge in the range of 50 volts to 1200 volts to the leformable material before or during heating by heating neans 16. The required minimum voltage is determined )y the frost threshold which in turn differs depending on he particular deformable material and on the surfactant. lhirty volts is about as low as the threshold can be brought with practical materials. Thus, the charge voltage must :xceed thirty volts. The higher the charge voltage, the more linear the development curve becomes until short :ircuit problems start to occur usually in excess of 1200 volts. Heat is applied until frosting occurs in the image areas. This will generally be when the heat has softened :he deformable material to a viscosity between about 10 and 10 poises.

FIG. 3 and FIG. 4 illustrate other methods of applying in image surface active material to imaging member 10. Thus, in FIG. 3, an original image to be reproduced is :hinly coated with volatile surfactant 19 over its image nearing surface. The original 18 is then positioned in face-to-face contact with deformable material 12. An infrared source 20 is then directed at the back of original 18. It should be understood that for this purpose, the Image areas of original 18 must preferentially absorb .nfrared light in relation to the non-image areas and that :he supporting substrate of the original must be transpar- :nt or translucent to infrared energy.

Infrared energy from source 2%) passes through the back 3f original 18 and is preferentially absorbed in the image areas causing selective heating of the image areas. This ;e1ective heating vaporizes some of the surface active ma- :erial from the face of original 18 so that it transfers to deformable material 12 in image configuration. The Jriginal is then separated from imaging member 10 and deformation image may be developed as described in rela- :ion to FIG. 2.

The present invention offers a simple and unique means for fingerprinting. One of the advantages of this means 3f fingerprinting is that it is readily adapted to producing projectable fingerprints. Thus, as illustrated in FIG. 4, in image forming member 10 similar to image forming rnember 10 of FIG. 1 and FIG. 3 is illustrated with a transparent substrate. The substrate is depicted as glass layer 21 coated with a transparent conductive layer such as stannic oxide coating 22. A layer of deformable ma- :erial 12 is coated over layer 22. To make a latent fingerprint image on the layer of deformable material 12, the subjects finger 23 is merely rolled lightly against the de- Eormable material in the way customarily used for ink fingerprinting, but without the use of ink. Human fingers normally have enough skin oil to provide the necessary surface active agent for operation in accordance with the present invention.

In fact, it has even been found desirable to clean the subjects hands before fingerprinting to avoid contaminating the deformable surface with a multitude of foreign materials which will tend to obscure the fingerprints rather than to help develop them. As long as the subjects hands are not obviously dirty, wiping the finger with facial tissues before fingerprinting is sufficient to insure good fingerprints. As with the embodiments of FIGURES l and 3, development is produced by electrostatic charging and heating as described in connection with FIG. 2. The frost image of the fingerprint thus produced can be readily projected by light transmitted through imaging member 10 and will readily produce a good high contrast image particularly if a Schlieren type optical system is used. If the substrate used in any of FIGURES 1, 3, and 4 is highly reflective, such as with polished aluminum, a Proxi projection system can be used for projecting the images. Such a system is described in Photographic Science and Engineering, March-April 1961 at pages 87 to 92. A continuous image forming system is illustrated in FIG. 5 for forming micro images by the inventive process. Imaging member 25 in accordance with this embodiment is a flexible web having a support layer in a substrate of a dimensionally stable flexible material such as polyethylene terepht-halate cellulose acetate or other similar plastic material. This substrate may itself be conductive as by the inclusion of a conductivity agent such as for example, stannic chloride just as suitably a conductive coating of evaporated metal or metallic oxide may be applied to the surface of the plastic substrate to provide the desired electrical conductivity. A layer of deformable material is then applied over the substrate and web 25 is positioned for support through an exposure station 26 by means of supply reel 27 and takeup reel 28 driven by motor 30.

An exposure station 26, a lens system 31 focuses an intense reduced size image of an original 32 on the deformable surface of web 25. While other means of projected original image can be used, the illustrated embodiment depicts the means of projecting the light image as one using a light reflected from the original. Light source 33 illuminates original 32 and the light passes through a prism 36. Prism 36 serves the purpose of a high efiiciency mirrorreversing the image sense and directing the projected image through lens system 31 to Web 25, to enable continuous image forming. A conventional slit 37 is used in the optical system. In operation, the deformable surface of web 25 is uniformly coated with a surfactant by roller 38 to which the surfactant is supplied by fountain device 40. The surfactant for this purpose is desirably a highly volatile material such as fluorocarbon, for example, FC43 fluorocarbon available from Minnesota Mining and Manufacturing. The image at exposure station 26 evaporates the surfactant in the background areas so that when the web is then electrostatically charged at charging station 41 and softened at soften-ing station 42, depicted as a heating oven, the deformable surface of web 25 frosts in the image areas. Web 25 is then reeled on reel 28 and stored for future use, while the image may be projected off the web immediately as desired. Since heating oven 42 vaporizes and removes most of the remaining surface active agent and the frost images formed on web 25 can be erased at any time by heating well above frost temperature until erasure is accomplished, web 25 may be reused repeatedly. Apparatus using xerographic method of applying the surface active agent is illustrated in FIG. 6. This apparatus comprises xerographic drum with conventional charging station 51, exposure station 52, development station 53, and transfer station positioned around it respectively in the direction of rotation. In operation, the Xerographic drum is charged at charging station 51 exposed to an original image 56 exposure station 52 and is developed in developing station 53. For purposes of the present invention, developing station 55 suitably comprises a spray or liquid vapor developing 4. A method of deforming an insulating thermoplastic layer according to claim 1 in which said surfactant is applied by a roller.

5. A vapor thermographic reproducing process commeans such as described, for example, in Carlson Patent 5 prising, in sequence, the steps of:

No. 2,551,582. This developing means is used to apply a colorless surface active agent to the latent electrostatic image on drum 50. At transfer station 55 a Web 62 of material having a deformable surface layer is supported in contact with the surface of the drum by supply reel 57, support rollers 58 and takeup reel 60. Xerographic drum 50 and takeup reel 60 are driven synchronously by motor 61. Web 62 can comprise a paper substrate with .a reflective conductive coating, such as an evaporated or laminated metallic coating. The reflective surface of the paper is coated with a layer of deformable material and the layer of deformable material is passed in contact with the xerographic drum While a transfer charge is applied to the back of the web by a charging device 63. This transfers the image of the surface active material to the deformable layer. Deformable layer is then electrostatically charged as by double corona charging device 65 followed by heating at a heating developing station 66. The frost image is developed on a web of the type described using a refractively coated paper backing. Projection of the image is readily obtained using a Proxy system as previously described. However, it is also possible in the embodiment of FIG. 6 to use a completely transparent web material such as described in connection with FIG. 5, for example, and view the frost image by transmitted rather than reflected light.

While the disclosed embodiments have been directed to processes in which the surfactant lowers the voltage threshold for frost surfactants can also be used to raise the voltage threshold for frost. Thus, for example, dimethyl polysiloxane, having a viscosity of 2,500,000 centistokes deposited on Staybelite 10 will raise the surface tension at the interface and increase the voltage threshold for frost. Photographic Gelatin (as defined in The Condensed Chemical Dictionary, Fourth Edition, 1950, Reinhold Publishing Corporation) also raises the interfacial tension and thus the frost threshold.

While the present invention has been described as carrying out specific embodiments thereof, there is no desire to be limited thereby. Other systems for using the present invention are readily thought of as for example, the latent image of surface active material may be formed by a spot scanning system in which the layer of deformable material is uniformly coated with a volatile surface active agent, and an intense modulated spot of light is used to scan the deformable surface to selectively evaporate the surface active agent. Accordingly, it is intended to cover the invention broadly within the scope of the appended claims.

What I claim is:

1. A method of deforming an insulating thermoplastic layer in accordance with a stencil pattern comprising, in sequence, the steps of:

(a) positioning a stencil of permeable and non-permeable areas in contact with said thermoplastic layer;

(b) applying a surfactant for said thermoplastic layer through said permeable areas;

(c) removing said stencil;

(d) electrostatically charging said thermoplastic layer and heating said thermoplastic layer until it reaches a viscosity between 10 and 10 poises whereupon deformation occurs in the stencil pattern.

2. A method of producing a deformation image according to claim 1 in which said surfactant is dimethyl polysiloxane.

3. A method of deforming an insulating thermoplastic layer according to claim 1 in which said surfactant is applied as an atomized spray.

(a) placing an original having an image surface carrying a volatile surfactant with said image surface in contact with a layer of deformable thermoplastic material;

(b) heating said original so that said volatile surfactant transfers to areas of said layer in contact With heated areas of said original;

(c) removing said original from said layer;

(d) electrostatically charging said layer; and,

(e) softening said layer until surfactant-bearing surface areas deform into minute random wrinkles;

(f) hardening said layer.

6. A vapor thermographic reproducing process according to claim 5 wherein said volatile surfactant is carried in the image areas only and said heating of said original is uniform.

7. A vapor therrnographic reproducing process according to claim 5 wherein said volatile surfactant is carried uniformly over the surface of said original and said heating of said original is selective to the image areas.

8. A vapor thermographic reproducing process according to claim 7 wherein said heating is by infrared light.

9. An inkless fingerprinting process comprising, in sequence, the steps of:

(a) transferring the natural skin oils of a subjects fingers to a layer of deformable thermoplastic material;

(b) electrostatically charging said layer; and,

(c) softening said layer until its surface deforms into an image pattern of the fingerprint;

(d) hardening said layer bearing said deformation image pattern.

10. A process for making microimage comprising:

(a) applying a volatile surfactant uniformly to the surface of a thermoplastic layer;

(b) intensely illuminating an original to be reproduced;

(c) focusing the light image produced by illuminating said original in reduced size onto said layer so as to selectively evaporate said surfactant from said layer;

(d) electrostatically charging said layers; and,

(e) softening said layer so that it deforms in minute random wrinkles in the areas where said light image did not evaporate said surfactant.

11. A process for forming a deformation image in a layer of thermoplastic material, comprising in sequence, the steps of:

(a) xerographically forming a latent electrostatic image on the surface of a xerographic drum;

(b) developing said latent electrostatic image with a surfactant for a layer of deformable thermoplastic material;

(c) transferring said surfactant to said layer of deformable thermoplastic material;

(d) charging said layer of deformable thermoplastic material; and,

(e) softening said layer of deformable thermoplastic material until it deforms into minute random wrinkling in the areas of transferred surfactant.

12. A method of producing a pattern upon an insulating thermoplastic layer, comprising in sequence the steps of:

(a) positioning a pattern-bearing stencil in contact with said thermoplastic layer;

(b) applying a surfactant to said thermoplastic layer through said stencil;

(c) removing said stencil;

(d) electrostaticaliy charging said thermoplastic layer;

7 (e) softening said thermoplastic layer until surfactant-bearing surface areas deform into randomly oriented ridges and valleys; (f) hardening said thermoplastic layer. 13. A method of producing a pattern upon an insulatg thermoplastic layer, comprising in sequence the steps (a) applying a surfactant to a thermoplastic layer in a desired pattern;

(b) electrostatically charging said thermoplastic layer;

(c) softening said thermoplastic layer until surfactantbearing surface areas deform into randomly oriented ridges and valleys; and,

(d) hardening said thermoplastic layer.

14. A method of producing a pattern upon an insulatlg thermoplastic layer comprising in sequence the steps (a) positioning a pattern bearing stencil in contact with said thermoplastic layer;

(b) applying a surfactant for said thermoplastic layer through said stencil;

(c) removing said stencil;

(d) electrostatically charging said thermoplastic layer;

(e) softening said thermoplastic layer until a deformation pattern forms thereon corresponding to the pattern of said stencil; and,

(f) hardening said thermoplastic layer.

15. A vapor thermographic reproducing process comprising in sequence the steps of:

(a) placing an original having an image surface carrying a volatile surfactant with said image surface in contact with a layer of deformable thermoplastic material;

(b) heating said original so that said volatile surfactant transfers to areas of said thermoplastic layer in contact with heated areas of said original;

(c) removing said original from said layer;

(d) electrostatically charging said layer;

(e) softening said thermoplastic layer until surfactant- 'bearing areas deform into randomly oriented alternating ridges and valleys of continually variable average depth; and;-..

(f) hardening said thermoplastic layer.

16. A vapor thermographic reproducing process acording to claim wherein said volatile surfactant is arried in the image areas only and said heating of said triginal is uniform.

17. A vapor thermographic reproducing process ac- :ording to claim 15 wherein said volatile surfactant is :arried uniformly over the surface of said original and aid heating of said original is selective to the image areas.

18. A process for forming a frost deformationpattern :omprising:

(b) softening said thermoplastic layer until areas hearing both electrical charge and surfactant deform into randomly oriented ridges and valleys; and then,

(c) hardening said thermoplastic layer.

19. process for forming a frost deformation pattern comprising:

(a) applying electrical charge on a first surface of a frostable, insulating, thermoplastic layer coated on at least a portion of said first surface with a thin layer of a voltage threshold reducing surfactant for said thermoplastic;

(b) softening said thermoplastic layer until areas hearing both electrical charge and surfactant deform into randomly oriented ridges and valleys; and then,

(c) hardening said thermoplastic layer.

20. A recording member comprising:

(a) a frostable, insulating thermoplastic layer and;

(b) a thin layer of a voltage threshold modifying surfactant on at least a portion of a surface of said thermoplastic layer.

21. A recording member according to claim 20 in which said surfactant layer has a thickness of less than about 0.5 micron.

22. A method for modifying the voltage threshold required to form a frost deformation pattern on a frostable insulating thermoplastic, comprising depositing a layer of a surfactant for said thermoplastic on the surface of said thermoplastic, said surfactant layer having a thickness of less than about 0.5 micron.

References Cited by the Examiner UNITED STATES PATENTS 2,020,376 11/1935 Rich 962.7 2,857,271 10/1958 Sugarman 961 2,896,507 7/1959 Mast et al 88--61 3,055,006 9/1962 Dreyfoos et a1. 961 X 3,079,253 2/1963 Greig 961 3,081,165 3/1963 Ebert 96-1 3,258,336 6/1966 Ewing 961.1

FORElGN PATENTS SHO-37-4484- 3/1960 Japan.

OTHER REFERENCES Gundlach et al.: A Cyclic Xerographic Method Based on Frost Deformation,.Phot. Sci. and Eng. vol. 7, No. 1, January 1963, pp. 1419.

Olin: Photoplastic Recording, Industrial and Engineering Chemistry, vol. 55, No. 6, June 1963, pp. 11 and 12. Claus: Advances in Xerography, Phot. Sci. and Eng,

' vol. 7, No. 1, January 1963, pp. 5-14.

NORMAN G. TORCHIN, Primary Examiner. J. T. BROWN, Examiner.

A. LIBERMAN, C. E. VAN HORN,

Assistant Examiners.

Claims (2)

13. A METHOD OF PRODUCING A PATTERN UPON AN INSULATING THERMOPLASTIC LAYER, COMPRISING IN SEQUENCE THE STEPS OF: (A) APPLYING A SURFACTANT TO A THERMOPLASTIC LAYER IN A DESIRED PATTERN; (B) ELECTROSTATICALLY CHARGING SAID THERMOPLASTIC LAYER; (C) SOFTENING SAID THERMOPLASTIC LAYER UNTIL SURFACTANTBEARING SURFACE AREAS DEFORM INTO RANDOMLY ORIENTED RIDGES AND VALLEYS; AND, (D) HARDENING SAID THERMOPLASTIC LAYER.

22. A METHOD FOR MODIFYING THE VOLTAGE THRESHOLD REQUIRED TO FORM A FROST DEFORMATION PATTERN ON A FROSTABLE INSULATING THERMOPLASTIC, COMPRISING DEPOSITING A LAYER OF A SURFACTANT FOR SAID THERMOPLASTIC ON THE SURFACE OF SAID THERMOPLASTIC, SAID SURFACTANT LAYER HAVING A THICKNESS OF LESS THAN ABOUT 0.5 MICRON.

Images