WO1997036726A2 - Systeme d'imagerie thermoplastique - Google Patents

Systeme d'imagerie thermoplastique Download PDF

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Publication number
WO1997036726A2
WO1997036726A2 PCT/US1997/004521 US9704521W WO9736726A2 WO 1997036726 A2 WO1997036726 A2 WO 1997036726A2 US 9704521 W US9704521 W US 9704521W WO 9736726 A2 WO9736726 A2 WO 9736726A2
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WO
WIPO (PCT)
Prior art keywords
layer
magnetic
thermoplastic
thermoplastic layer
stack
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1997/004521
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English (en)
Other versions
WO1997036726A3 (fr
Inventor
Alexander Chaihorsky
Michael Rusanov
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ULTRA-RES CORP
Original Assignee
ULTRA-RES CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ULTRA-RES CORP filed Critical ULTRA-RES CORP
Priority to AU34726/97A priority Critical patent/AU3472697A/en
Publication of WO1997036726A2 publication Critical patent/WO1997036726A2/fr
Anticipated expiration legal-status Critical
Publication of WO1997036726A3 publication Critical patent/WO1997036726A3/fr
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G16/00—Electrographic processes using deformation of thermoplastic layers; Apparatus therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording-members for original recording by exposure, e.g. to light, to heat or to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/022—Layers for surface-deformation imaging, e.g. frost imaging
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H2001/026—Recording materials or recording processes
    • G03H2001/0264—Organic recording material

Definitions

  • thermoplastic imaging system of the type in which a thermoplastic material can be electrostatically shaped by softening of the thermo ⁇ plastic and rehardening to alter the surface or structure of the thermoplastic in response to a latent image formed by electrostatically charging the system in the presence of a photosensitive semiconductor.
  • the invention therefore, relates to thermographic materials, i.e. a film which can be provided with an image in the form of changes in the thermo ⁇ plastic structure, to a method of producing such images and to equipment utilizing such film.
  • a conductive layer forms an electrode for charging the film and a semicon ⁇ ductive layer, especially an amorphous inorganic semiconduc ⁇ tor, is provided to generate a latent image upon appropriate exposure.
  • the semiconductor layer is disposed adjacent a thermoplastic layer which carries the electric charge when the film is charged.
  • the application of heat to soften the ther ⁇ moplastic layer causes changes in the thermoplastic structure which may result in deformation on the surface of the film based upon the charge distribution and/or changes in internal refractivity or optical conductivity, by reason of polymeri ⁇ zation, chain modifications and the like, or any combination of the two so that, upon cooling, an image is fixed in the film which can be viewed when light is directed onto the thermographic material.
  • Such systems have been found to be particularly effective in the production of so-called instant holograms, i.e. for a form of holography which allows the holographer to permanently capture a hologram instantly and without a dark ⁇ room, developing chemicals, or any of the much more complex development techniques previously required.
  • the film depend ⁇ ing upon construction, transparency and the like can be used for transmission and reflection holograms, and the applica ⁇ tions of the film can include interfero etry, security appli ⁇ cations, verification, authentication, etc.
  • the film may be used for other optical image reproduction or production tech ⁇ niques as well.
  • thermographic imaging utilizing thermally introduced changes in a thermoplastic layer to develop an image corresponding to a latent image resulting from a charge distribution, that layer in which the thermo ⁇ plastic layer contains a particulate magnetic material which can be affected by an applied magnetic field.
  • thermo ⁇ static charge intensity which is required to effect distortion of the thermoplastic layer can be reduced if, simultaneously with the heating of the thermoplastic layer, a magnetic field is applied to the material.
  • a magnetic latent image may be applied for superimposition upon the electrostatic latent image utilizing magnetic recording means if desired and the magnetic material present in the thermo ⁇ plastic layer may be used to record information in addition to image information in the form of the magnetic latent image mentioned above.
  • information as to the extent of expo ⁇ sure to light e.g. to laser beams in the case of a holo ⁇ graphic system or information as to degree of heating may be recorded in the film and can be read at the camera or other equipment for processing the film.
  • the magnetic material which can be used includes any of the particulate materials utilized in the production of magnetic recording tapes and like magnetic imaging, including ferrites, and other iron oxides, chromium oxides and the like, as well as particulate permanent magnet materials.
  • the mag ⁇ netic materials can be homogeneously distributed in the ther ⁇ moplastic layer or can be distributed in a particular pattern therein.
  • the amount of magnetic material should be the maxi ⁇ mum which can be accommodated without detriment to the physi ⁇ cal properties of the thermoplastic layer and to the electro ⁇ static recording properties thereof and the particle size of the magnetic material should be the smallest possible to ensure the highest resolution.
  • thermoplastic layer One of the surprising advantages of the presence of magnetic materials in the thermoplastic layer is an increase in the photosensitivity of the film so that lesser levels of light or lower intensity can produce the latent image.
  • the presence of the magnetic material and the use of a magnetic field conjointly with heating increases the signals to noise ratio of the registered image and allows lower voltage levels to be employed for charging the film, thereby reducing any adverse effect of corona instability.
  • the magnetic material can be ⁇ -Fe 2 0 3 while some 5 to 25% of the thermoplastic layer may consist of the magnetic powder.
  • the particle size of the magnetic powder should be from 0.005 to about 0.09 ⁇ m with best results about 0.03 ⁇ m.
  • the thermoplastic layer can be composed of a copoly ⁇ mer of styrene and butylmethacrylate which consists of 25 to 75% styrene and 75 to 25% butylmethacrylate, with good results being a 50% by weight styrene and 50% by weight butylmethacrylate composition.
  • the thickness of the thermo ⁇ plastic layer may range from 0.5 to 2.5 ⁇ m and preferably is around 1.5 ⁇ m.
  • the magnetic powder is suspended in the polymer composition dissolved in toluene or some other solvent and the solvent is evaporated.
  • the photosensitive layer can be an amorphous semi ⁇ conductor of the arsenic-sulfur, arsenic-selenium or arsenic- sulfur-selenium type.
  • Typical of the amorphous inorganic semiconductors used may be those having a formula in the range (As 2 S 3 ) 0 . 3 (As 2 Se 3 ) 0 . 7 to (As 2 S 3 ) 0 . 5 (As 2 Se 3 ) 0 . 5 .
  • the presence of the magnetic material distributed in the thermoplastic layer allows the molecular movement of the magnetic particles to be detected during the heating process and permits, according to the invention, control of the heat ⁇ ing process during the latter so as to achieve particularly efficient control of the heating and highly reproducible imaging results.
  • the molecular movement in the thermoplastic layer and hence movement of the magnetic particles is a direct reflection of the temperature of the body of thermoplastic and can be measured with particularly high precision by conven ⁇ tional magnetometers. The latter can be used to regulate the heating or to cut it off when the desired temperature or degree of heating has been obtained.
  • the magnetic material is Fe 3 0 4 and the Fe 3 0 ⁇
  • powder is present in an amount of 7% by weight of the thermoplastic layer.
  • 93% by weight of the layer may be composed of polyepoxypropylcarbazole admixed with about 30% by weight of dioctylphthalate.
  • the magnetic powder need not be incorporated into the thermoplastic layer exclusively and some or all of the magnetic powder may form a magnetic powder layer on the thermoplastic layer.
  • the thermo- plastic layer can include 100% of an intimate blend of the polyepoxypropylcarbazole with the 30% by weight of dioctyl ⁇ phthalate and the magnetic particle layer may be used in a homogeneous and uniform thickness layer in an amount of 7% by weight of the thermoplastic layer.
  • the magnetic particle layer can be of a thickness equal to the order of the particle size, namely 0.09 ⁇ m to 0.005 ⁇ m
  • a preferred thickness is about 2.0 ⁇ m.
  • association can involve:
  • thermoplastic layer (a) a uniform dispersion of the magnetic powder in the thermoplastic layer
  • thermoplastic layer i.e. a graded distribution of the magnetic powder in the thermoplastic layer, i.e. a variation in the concentration of the magnetic powder from one side of the thermoplastic layer to the other;
  • thermoplastic layer A layer of the magnetic powder along one or both of the surfaces of the thermoplastic layer; (d) a combination of a layer of the magnetic powder along one or both of the surfaces of the thermoplastic layer with the incorporation of particles in the thermoplastic mass as in (a) or (b) ; or
  • thermo ⁇ plastic material (e) a sandwich construction in which a layer of the magnetic material is sandwiched between layers of the thermo ⁇ plastic material, possibly in combination with incorporation of magnetic particles in one or the other of the sandwiching layers.
  • a stack or laminate according to the invention can also include a very thin layer of ferromagnetic material of a surface-active substance.
  • the latent image may be generated by other means, for example, electrostatically applied to the layer of thermoplastic material by other than the use of a photoconductor.
  • the imaging material may in ⁇ clude an electrode to assist in the application of the elec ⁇ trostatic charge but even may be free from an electrically conductive layer when the latent image is generated, for example, by other electrostatic means or by magnetic means.
  • the application of a magnetic field to enhance the thermo ⁇ graphic effect remains and the latent image can be developed by heating to effect the structural change in the thermoplas ⁇ tic material.
  • the method of the invention can then comprise the steps of: (a) providing an imaging material comprised at least of a layer of a thermoplastic material and magnetic particles associated with the layer;
  • FIG. 1 is a diagrammatic section through an imaging material in accordance with the invention
  • FIG. 2 is a diagram of method steps of the inven ⁇ tion
  • FIG. 3 illustrates a surface pattern created utiliz ⁇ ing the material of the invention in a cross sectional view drawn to a larger scale than FIG. 1;
  • FIG. 4 is a diagram illustrating another aspect of the invention.
  • FIG. 5 is a cross sectional view similar to FIG. 1 showing another imaging material in accordance with the inven ⁇ tion;
  • FIG. 6 is a cross sectional view of a thermographic imaging material which does not utilize a photoconductor within the material according to another feature of this invention.
  • FIG. 7 is a cross sectional view through a thermo ⁇ graphic material representing a modification of the material of FIG. 6.
  • the imaging material shown in FIG. 1 has been de ⁇ picted with exaggerated thicknesses of the various layers and has been illustrated in a particular stack configuration although it should be understood that the layers may be switched in location or additional layers may be produced as long as the conductive layer enables charging of the stack, the layers are disposed so that the light, e.g. laser illumi ⁇ nation, can reach the photo-sensitive semiconductive layer, the heating can be applied to the thermoplastic layer and the entire stack is supported so that, when the thermoplastic layer has its structure altered, the alterations can affect light which is transmitted through the film or reflected from it so that the image can be displayed.
  • the layers may be switched in location or additional layers may be produced as long as the conductive layer enables charging of the stack, the layers are disposed so that the light, e.g. laser illumi ⁇ nation, can reach the photo-sensitive semiconductive layer, the heating can be applied to the thermoplastic layer and the entire stack is supported so that, when the thermoplastic layer has its structure altered, the alterations can affect light which
  • the material of FIG. 1 can com ⁇ prise a support 10, preferably of a polyester but also, if desired, of any other transparent or translucent material with a melting point well above the softening temperature of the thermoplastic layer, the ability to receive an adherent coat ⁇ ing and optical properties which do not interfere with expo ⁇ sure of the photosen-sitive layer or the transmission or reflection reproduction of the resulting image.
  • the support should be a good heat conductor as well to ensure that, if the heating of the thermoplastic layer is effected by contact with a heated surface applied to the polyester support, the latter will not prevent raising the temperature of the thermoplastic layer to the softening point.
  • the layer 10 is preferably composed of Mylar, i.e. a polyethylene terephthalate.
  • a metallic layer 11 which constitutes an electrode, e.g. of aluminum or chromium.
  • the thickness of this layer is not significant and it may be a monolayer. Its purpose is to enable the charging of the stack electrostatically. It may be connected to a conductive sur ⁇ face of a frame in the case of a slide or may otherwise be exposed so that it can be connected to one pole of an elec ⁇ trode charging source or grounded when a pole of that source is grounded.
  • the metallic layer 11 On the metallic layer 11 is a layer of an arsenic- sulfur, arsenic-selenium or arsenic-sulfur-selenium amorphous semiconductor of a formula in the range given above.
  • the semiconductor is photosensitive material which, when exposed to light, will alter the uniformity of an electrostatic charge applied to the stack to produce a latent image.
  • thermoplastic preferably the styrene-butyl- methacrylate copolymer (50% styrene, 50% butylmethacrylate) which can contain 13% by weight of magnetic powder as repre ⁇ sented at 14, the magnetic powder being, for example, ⁇ -Fe 2 0 3 of a particle size of about 0.03 ⁇ m.
  • the thickness of the thermoplastic layer is about 1.5 ⁇ m.
  • the stack 11-14 and repre ⁇ sented at 15 in FIG. 2 is charged by being exposed to a corona discharge electrode connected to a high voltage dc source 17 whose other pole is grounded, the layer 11 being grounded as being represented at 18.
  • the result is a uniform electrostatic charge on the thermoplastic layer 13.
  • the photosensitive semiconductor is activated to alter the electrostatic charge distribution, thereby creat ⁇ ing a latent image in the material based upon the electro ⁇ static charge distribution. Heat can then be applied to a surface of the stack 15, e.g.
  • thermoplastic layer 13 as shown in FIG. 3 or changes are made in the polymer structure itself.
  • a magnetic field is applied trans ⁇ versely to the layer, e.g. by a solenoid 24 (FIG. 2) , the magnetic field being represented at H.
  • the image resolution can be increased to 1500 mm- 1
  • the diffraction efficiency can be not less than 15%
  • the signal to noise ratio can be increased to three times that of a system without the application of the magnetic field and magnetic particles.
  • An induction field of 9567 A/m 2 can induce deforma ⁇ tion in the thermoplastic when heated to its softening point without the optically produced latent image to generate a pattern on the thermoplastic surface which corresponds to the distribution of the particles in the thermoplastic and hence a magnetic latent image therein.
  • the system can be used, by controlled distribu ⁇ tion of the magnetic particles in the thermoplastic layer, to create a latent image therein which is developed by the appli ⁇ cation of the magnetic field simultaneously with heating and, when an optical latent image is provided, can superimpose the magnetic image on the optical image.
  • the magnetic material also forms an ideal recording medium and in that case a mag ⁇ netic head can record at 30 on the slide, whatever information may be of interest where the hologram is part of a document security item or for other purposes, the material being read at 31, e.g. by a reading head in the camera with the informa ⁇ tion being displayed from the reading head or used to control the exposure, heating and magnetic field application in the camera as represented at 32.
  • the magnetometer or other measuring device 33 for the magnetic field in the vicinity of the film is coupled to the heater to control the latter in response to measurements of the magnetic field resulting from the presence of the magnetic particles.
  • the imaging material which can be used in the manner already described and with the apparatus which has been described, comprises a polyester support 10, the conduc ⁇ tive layer 11 and the layer 12 of amorphous semiconductor, all as has been described.
  • the thermoplastic layer 13 is composed of the polyepoxypropylcarbazole contain ⁇ ing 30% by weight of dioctylphthalate and the magnetic parti ⁇ cles are provided in a magnetic powder layer 14 • on the ther ⁇ moplastic layer and consists of Fe 3 0 particles in a particle size of about 0.3 ⁇ m and a thickness of about 0.1 ⁇ m.
  • a further protective film 13' of the polyepoxypropylcarbazole and dioctylphthalate blend is provided on the magnetic powder layer.
  • That film operates as has been described for the film of FIG. 1.
  • the imaging material consists of a polyestertere- phthlate support having a thickness of 100 ⁇ m and onto which a conductive chromium layer is vapor-deposited to a thickness of 0.01 ⁇ m. On this conductive layer, an amorphous photoconductive layer of an arsenic-sulfur-selenium composi ⁇ tion is applied. This composition consists 30% by weight of As 2 S : 5 Se ! 5 . The amorphous semiconductor layer has a thickness of 2 ⁇ m.
  • thermoplastic layer of polyepoxypropylcarbazole containing 30% by weight dioctylphthalate and 7% by weight of Fe 3 0 4 magnetic powder of a particle size of 0.03 ⁇ m is applied.
  • the resulting film is placed in a recording device as has been described and is heated for 5 seconds to a record ⁇ ing temperature of 80 ⁇ C.
  • the corona electrode potential is 5.5 kV.
  • a magnetic field with an intensity of 600 Oersted was applied perpendicular to the surface of the thermoplastic medium over a period of 60 seconds.
  • the recording stack was exposed to the corona discharge of 5.5 kV and after a further second was exposed to light from the image for a period of one second.
  • a photographic sensitivity was not less than 20 (lux.sec) 1 and the resolution was 1.5 times higher than that of a photothermoplastic medium without the magnetic particles and exposure to the magnetic film.
  • thermographic material which omits the photoconductive layer and thus, on a polyester film base 10, can have the conductive layer 11 and a thermo ⁇ plastic layer 13 of the type described in which magnetic particles 14 are dispersed.
  • an electrostatic charge can be applied to the thermoplas ⁇ tic layer 13 and a latent image can be formed electro ⁇ statically in the material by, for example, differential discharge of the electrostatic charge or by controlling how the electrostatic charge is originally applied. If the con ⁇ ductive layer 11 is omitted, the material can be electro ⁇ statically charged by plates flanking the material. In another alternative, the latent image can be formed magnetically by providing different magnetic fields to various locations of the film.
  • the film can then be subjected as has been described to heating to develop the latent image and form a sensible image, i.e. an image which can be sensed by the passage of light through the film or by reflecting light from the film.
  • a sensible image i.e. an image which can be sensed by the passage of light through the film or by reflecting light from the film.
  • the resolution can be enhanced by the applica ⁇ tion of a magnetic field in the manner already described.
  • FIG. 7 we have shown a material similar to FIG. 6 but wherein the magnetic particles form a layer 14 • which is protected by an additional layer 13' of the thermoplastic.
  • the film of FIG. 7 is used in a similar manner to the film of FIG. 6.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)

Abstract

L'invention se rapporte à un matériau thermographique du type dans lequel une couche thermoplastique placée sur un semi-conducteur photosensible est chargée électrostatiquement et la pile est ensuite chauffée de façon que la charge induise des modifications structurelles dans la couche thermoplastique pour produire un hologramme ou une autre image. La couche thermoplastique contient ou est constituée d'une couche de particules magnétiques, par exemple de δFe2O3 ou de Fe3O4, qui, lorsqu'un champ magnétique est appliqué simultanément à la chaleur, améliore considérablement les résultats du rapport signal/bruit du système d'imagerie.
PCT/US1997/004521 1996-03-18 1997-03-17 Systeme d'imagerie thermoplastique Ceased WO1997036726A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU34726/97A AU3472697A (en) 1996-03-18 1997-03-17 Thermoplastic imaging system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1357896P 1996-03-18 1996-03-18
US60/013,578 1996-03-18

Publications (2)

Publication Number Publication Date
WO1997036726A2 true WO1997036726A2 (fr) 1997-10-09
WO1997036726A3 WO1997036726A3 (fr) 1999-06-24

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Application Number Title Priority Date Filing Date
PCT/US1997/004521 Ceased WO1997036726A2 (fr) 1996-03-18 1997-03-17 Systeme d'imagerie thermoplastique

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AU (1) AU3472697A (fr)
WO (1) WO1997036726A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
MD4237C1 (ro) * 2012-04-24 2014-01-31 Государственный Университет Молд0 Purtător fototermoplastic pentru înregistrarea informaţiei optice
US8836331B2 (en) 2004-03-25 2014-09-16 Dai Nippon Printing Co., Ltd. Volume hologram resin composition, surface relief hologram resin composition, and hologram layer, hologram transfer foil and brittle hologram label using the same

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627682A (en) * 1968-10-16 1971-12-14 Du Pont Encapsulated particulate binary magnetic toners for developing images
US3850627A (en) * 1971-01-06 1974-11-26 Xerox Corp Electrophoretic imaging method
US4880857A (en) * 1986-12-17 1989-11-14 Nippon Shokubai Kagaku Kogyo Co., Ltd. Carbon black-graft polymer, method for production thereof, and use thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8836331B2 (en) 2004-03-25 2014-09-16 Dai Nippon Printing Co., Ltd. Volume hologram resin composition, surface relief hologram resin composition, and hologram layer, hologram transfer foil and brittle hologram label using the same
MD4237C1 (ro) * 2012-04-24 2014-01-31 Государственный Университет Молд0 Purtător fototermoplastic pentru înregistrarea informaţiei optice

Also Published As

Publication number Publication date
WO1997036726A3 (fr) 1999-06-24
AU3472697A (en) 1997-10-22

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