US3485623A - Continuous tone thermoplastic photography - Google Patents

Continuous tone thermoplastic photography Download PDF

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Publication number
US3485623A
US3485623A US541835A US3485623DA US3485623A US 3485623 A US3485623 A US 3485623A US 541835 A US541835 A US 541835A US 3485623D A US3485623D A US 3485623DA US 3485623 A US3485623 A US 3485623A
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United States
Prior art keywords
exposure
frostable
curves
layer
potential
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Expired - Lifetime
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US541835A
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English (en)
Inventor
Robert A Wilferth
Peter B Keenan
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Xerox Corp
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Xerox Corp
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Publication date
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    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • ABSTRACT OF THE DISCLOSURE A process enabling control of the photo-response characteristics of a frostable member wherein the initial charging and recharging potentials are altered so as to adjust the spread between that exposure which results in threshold frosting and that exposure which results in maximum frosting until this exposure spread is in such ratio to the difference between image density present at threshold frosting and image density present at maximum frosting as to produce the desired gamma in the particular frostable member being utilized.
  • This invention relates generally to deformation imaging processes and, more specifically, to processes of the type identified as electrostatic frosting.
  • the frost images to which the present invention is applicable display continuous-tone reproduction capabilities much like conventional silver halide images. Clarification of the type of problem to which the present invention addresses itself may in fact be best gained by considering the semianalogous silver halide images somewhat further and in particular noting that one of the most important characteristics of such images derives from the fact that the relationship present therein between image density and exposurewhich is to say the so-called gamma of the photographic emulsion-may be controllably varied by development processes, and so forth, so as to augment or lessen the gamma characteristics of the film.
  • It4 is a further object of the present invention to provide a process whereby the gamma characteristics of a frostable member may be adjusted to suit the requirements of a user.
  • FIGURE l is a graphic representation of a three layer frostable photoreceptor member of the type utilized in the present invention.
  • FIGURE 2 is a representative curve illustrating the relationship between frost density and surface charge density achieved on a member of the type depicted in FIGURE l.
  • FIGURES 3 and 4 are analytical curves depicting how in the practice of the present invention, surface potential and surface charge densities on members as in FIGURE l may be expected to vary with the log of exposure.
  • FIGURES 5 and 6 are empirical ⁇ curves depicting variations of the type shown in FIGURES 3 and 4 for the exemplary member set forth in Example I.
  • FIGURE 1 a typical frostable photoreceptor device is depicted, generally resembeling the frostable members described in connection with the Gunther and Gundlach patent previously alluded to.
  • This frostable member 1 is seen to include a conductive substrate 2 conveniently comprising a thin sheet of aluminum, a photoconductive layer at 4, and an overcoated frostable layer at 6.
  • the photoconductive layer may be considered to comprise a layer of vitreous selenium having a thickness designated as ds and a permittivity designated as es; however, in some instances this layer will actually be compound in nature and consist of a lower portion of selenium alone intended to exercise a charge storage function, and an upper portion comprising a relatively panchromatic selenium-tellurium alloy and intended to function as the photoconductor proper.
  • the upper most layer 6, the frostable component, is shown in FIGURE 1 as having a thickness dp and a permittivity designated as ep.
  • a list of materials suitable for this frostable component is indicated in the Gunther and Gundlach patent previously mentioned.
  • such layer will comprise a few microns thick coating of Staybelite Ester-10 (glyceryl tri-ester of 50% hydrogenated wood resin) available under the trade name indicated from the Hercules Powder Company, Wilmington, Del.
  • an interlayer comprising several hundredths of a micron of an organic material may be applied between the photoconductive layer 4 and the lfrostable layer 6, as such interlayer appears t operate in some obscure manner to increase resolution in the final frosted image.
  • this interlayer need not be specically considered or included and in any event may for purposes of analysis be thought of as included in the frostable layer 6.
  • the frostable member 1 is initially provided with charge on the surface of layer y6 by moving the member relative to a corona charging device or the like.
  • the member is then exposed to a pattern of light and shadow as, for example, by means of a photographic enlarger or the like, which permits migration of charges in portions of the photoconductive layer 4 adjacent to light exposed areas on the member.
  • These migrating charges become bound at the interface between layers 4 and 6 with a resulting lowering of potential at corresponding points on the surface of the deformable layer 6.
  • the layer 6 is recharged by the same or a similar corona device so as to bring the surface ⁇ 6 once again to an equipotential.
  • FIGURE 2 a representative curve is shown illustrating the typical experimental frost density achieved upon such a frostable member as a function of the charge density present on the member after recharging.
  • density refers to the light attenuation, 1.e.,
  • the essence of the present invention resides principally in the discovery of a technique whereby the range of frost densities extending between aT and Umax may be made to coincide with exposure ranges of varying widths.
  • the discovery will further be seen in what ensues to indicate a method for adjusting the sensitivity of the photoresponsive member-at least to a reasonable degree.
  • the effect of dark decay cannot be distinguished from effects of exposure; therefore, the change in surface potential AV includes exposure and dark decay.
  • the charge at the interface UE includes the charge due to exposure and dark decay.
  • VE U0 da
  • the photoreceptor member 1 is then recharged to restore the condition of an equipotential surface. Charging to a potential VR(VR V0) will result in a surface charge density URE in the exposed area and RD in an unexposed area. Hence, in the dark R RD el en and in the exposed area magg-ag) l D B By combining the values of AV and VR the surface charge density in the exposed area is found to be This analysis shows that the final surface charge density is a function of--among other thingsthe two independent processing parameters representd by the initial potential V0 and the recharge potential VR, as well as of the exposure.
  • FIGURE 3 illustrates a representative set of curves that result on utilizing Equation 1 to determine surface charge density URE as a function of log exposure for a representative device constructed in accord with FIGURE 1.
  • Variation in surface potential, VE as a result of exposure and before recharge is also shown on the same set of axes.
  • Exposure units in FIGURE 3 may be assumed to be relative, absolute values not being of any particular relevance to the present discussion.
  • Curves 1 and 2 in FIGURE 3 show the values for initial and recharge potentials equal to 400 volts each.
  • Curves 3 and 4 show the values for an initial potential of 200 volts and recharge potential of 550 volts. It may be noted in these curves that, as would be expected, the charge density curves at 2 and 4 are mirror images of the potential curves at 1 and 3. It will also be noted as a general feature that curves 1 and 2 join at the vertical axis whereas 3 and 4 are separated by a degree that results from the voltage differential between the initial potential and the recharge potential utilized.
  • a frostable photoreceptor member essentially in struc- 'tural accord with that depicted in FIGURE 1 was prepared wherein the substrate 2 comprised an anodized aluminum sheet 0.05 inch thick.
  • the layer in the instant example was compound and included a selenium charge storage layer 25 microns thick adjacent the conductive substrate.
  • a .3 micron thick photosensitive layer comprising an alloy having a nominal composition of 75% selenium and 25% tellurium, the latter layer by virtue of its composition exhibiting generally panchromatic light response.
  • an interlayer of an organic material about 0.05 micron thick was applied over the photosensitive selenium tellurium layer, its function being to obtain the maximum possible resolution with the device. The mechanism of operation of this interlayer is not clear.
  • thermoplastic frostable layer corresponding to 6 in FIGURE 1.
  • this layer comprised about 2 microns of Staybelite Ester-10 (glyceryl tri-ester of 50% hydrogenated wood resin). This particular material is available under the trade name indicated from the Hercules Powder Company, Wilmington, Del. Storage layers and photosensitive layers were applied by vacuum deposition. The interlayer and the frostable layer were applied by dip coating from a solution.
  • a method for adjusting the gamma response in a frostable photoreceptor member including a conductive substrate overcoated with a photoconductive layer of thickness ds and permittivity es in turn overcoated with a deformable frostable thermoplastic layer of thickness dp and permittivity ep comprising:
  • a method for varying the gamma characteristics of a frostable photoreceptor member comprising initially charging said member to a potential V0 and, subsequent to exposure to an image, recharging said member to a potential VR where the ratio of the absolute values V0 to VR is less than unity.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US541835A 1966-04-11 1966-04-11 Continuous tone thermoplastic photography Expired - Lifetime US3485623A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US54183566A 1966-04-11 1966-04-11

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US3485623A true US3485623A (en) 1969-12-23

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US (1) US3485623A (de)
DE (1) DE1572360B2 (de)
GB (1) GB1181093A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4059827A (en) * 1975-03-13 1977-11-22 The Marconi Company Limited Molecular information storage systems
US20020155355A1 (en) * 2000-06-08 2002-10-24 Holotech A.S Device for registration of optical holograms on the amorphous molecular semiconductor films
US20060015996A1 (en) * 2002-05-14 2006-01-26 Goettl John M Swimming pool drain

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3196011A (en) * 1962-05-08 1965-07-20 Xerox Corp Electrostatic frosting
US3196008A (en) * 1962-05-08 1965-07-20 Xerox Corp Electrophotographic process for formation of frost-like deformation images in mechanically deformable photoconductive layers

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3196011A (en) * 1962-05-08 1965-07-20 Xerox Corp Electrostatic frosting
US3196008A (en) * 1962-05-08 1965-07-20 Xerox Corp Electrophotographic process for formation of frost-like deformation images in mechanically deformable photoconductive layers

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4059827A (en) * 1975-03-13 1977-11-22 The Marconi Company Limited Molecular information storage systems
US20020155355A1 (en) * 2000-06-08 2002-10-24 Holotech A.S Device for registration of optical holograms on the amorphous molecular semiconductor films
US6998197B2 (en) * 2000-06-08 2006-02-14 Holotech A.S. Device for registration of optical holograms on the amorphous molecular semiconductor films
US20060015996A1 (en) * 2002-05-14 2006-01-26 Goettl John M Swimming pool drain
US20090007325A9 (en) * 2002-05-14 2009-01-08 Goettl John M Swimming pool drain

Also Published As

Publication number Publication date
DE1572360A1 (de) 1970-02-19
DE1572360B2 (de) 1976-04-15
GB1181093A (en) 1970-02-11

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