US3249430A - Process for producing images in electrophotography and radiography - Google Patents

Process for producing images in electrophotography and radiography Download PDF

Info

Publication number
US3249430A
US3249430A US128882A US12888261A US3249430A US 3249430 A US3249430 A US 3249430A US 128882 A US128882 A US 128882A US 12888261 A US12888261 A US 12888261A US 3249430 A US3249430 A US 3249430A
Authority
US
United States
Prior art keywords
photo
conductor
charge
light
image
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.)
Expired - Lifetime
Application number
US128882A
Other languages
English (en)
Inventor
Kenneth A Metcalfe
Robert J Wright
Robert V Wissell
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.)
Australian Government
Original Assignee
Australian Government
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
Priority claimed from AU63314/60A external-priority patent/AU253042B2/en
Application filed by Australian Government filed Critical Australian Government
Application granted granted Critical
Publication of US3249430A publication Critical patent/US3249430A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/04—Exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • 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
    • Y10S430/167—X-ray

Definitions

  • This invention relates to an improved process for controlling contrast when producing images in electrophotography and radiography.
  • the customary method of producing an image in electrophotography and radiography is to charge a xerographic paper or film by subjecting it to a corona discharge and to then light-modify the charged medium, after which development is carried out by any of the known xerographic processes.
  • the xerographic surface is conditioned so that both the charge holding ability, i.e., the amount of charge for a given voltage which can be held by the xerographic surface and its charge leakage rate is decreased.
  • the invention therefore consists in the method of controlling contrast of a xerographic image which embodies the steps of first exposing a photo-conductor surface to electromagnetic waves which can be absorbed by the photo-conductor whereby both its charge holding ability and its leakage rate is decreased, then charging the so modified photo-conductor in the absence of light by subjecting to a corona discharge to produce a uniform electric charge on the photo-conductor, then exposing the surface to electromagnetic Waves of the required pattern to differentially bleed away the charge and produce an electrostatic image, and then developing the electrostatic image by applying a developer which deposits according to the electrostatic pattern.
  • the invention thus shows that when a photo-conductor medium is subjected to pre-exposure to a relatively strong light, or other electromagnetic wave, the photo-conductor medium is rendered more conductive than it is when it is dark-rested. This has the effect that when it is subjected to electrons, the electrons result in a lower fiux density immediately above the zinc oxide layer which is equivalent to a much lower voltage on the surface while the modified condition maintains.
  • the amount of light or other electromagnetic wave used for conditioning is much greater than for exposure.
  • the secondary yield of carriers, namely the second exposure, is taking place from material deficient in easily produced carriers so the yield per photon is less. This means that there is a lower decay rate for conditioned areas.
  • the conductive backing or substrate which is otherwise necessary between the paper or other backing and the photo-conductor medium is not necessary when this invention is practised, the photo-conductor medium itself acting as the conductive backing so that a relatively low charge only can be maintained on the immediate outer surface of the photo-conductor material.
  • the photo-conductor medium was applied to an insulating film without a conductive backing and, only when pre-modified by light, could a satisfactory picture be obtained.
  • a photo-conductor medium such as zinc oxide, which is highly sensitive to light conditioning by visible rays of light, provides an efiective medium for carrying the invention into effect
  • materials which can be preconditioned by exposure to electromagnetic waves to cause the materials to be what we term fatigued or electro magnetic Wave conditioned to charging by electron means in their pre-conditioned state with better controlled development of such an image by xerographic means.
  • curves showing dark and light decay characteristics of zinc oxide paper under different pre-exposure conditions will now be referred to, the curves being designated FIGURES 1 to 6 and showing respectively the effects of pre-treatment of dark-rested xerographic paper, and the image exposure curves where the paper is exposed to various degrees and sources of electromagnetic energy.
  • FIGURE 1 the surface charge remaining on a zinc I oxide papers is shown by the curves A and B and C respectively where in curve A the paper has been dark-rested to remove fatigue of the zinc oxide, in curve B a preexposure for 10 seconds to visible light has been made, and in curve C a pro-exposure of 30 seconds to visible light has been made, the source of illumination in each case being a Watt actinic lamp spaced at six inches from the zinc oxide paper, giving a luminance of 1,130 candles per square foot.
  • the charge drops down respectively to volts, 100 volts, and 65 volts, while after one hour of dark resting, the respective voltages are 150, 80 and 50 volts.
  • FIGURE 2 the voltages are shown where the photoconductor is charged in a similar manner but the paper is then exposed to light of 200 candles per foot to give a light decay curve, in which case it will be noted that curves A and B after one second have dropped down materially below curve C which itself remains almost unaltered in its slope under the conditions of both FIGURE 1 and FIGURE 2.
  • FIGURE 3 the surface charge remaining on the Zinc oxide paper is again shown by c-urves A, B and C respectively wherein curve A the paper has been darkrested while in B a pre-exposure of 2.5 seconds has been made, the ultra violet source being a 125 watt Hanovia black lamp with filter placed 10 inches from the paper while C shows the curve where a 30 second exposure to the same ultra violet source was made.
  • FIGURE 4 the voltages are shown where the photoconductor is electrically charged in a similar manner but the paper is dark rested in curve A, has an exposure of 2.5 seconds to an ultra violet light source before charging in curve B.
  • curve C a 30 second exposure was used under similar conditions, showing that the effective light then is very materially altered.
  • Curve A shows that a high charge can be taken initially where no pre-treatment with ultra violet light has existed, but the charge has bled away almost completely in one second.
  • a short pre-charge under ultra violet light has taken place as in case B the electrical resistance of the zinc oxide film has been altered so that now only approximately 150 volts can be held for the same charge effect, andthis again bleeds away in something under a second.
  • FIGURES 5 and 6 are similar to FIGURES 3 and 4 except that the pre-treatment of the paper has now been carried out with X-rays, the charging having been effected under curve B by exposure for ten milliampere minutes to 120 kv. at a distance of 12 inches.
  • zinc oxide can suitably be treated by electromagnetic waves of a wave length somewhere between 3,000 to 4,000 angstrom units, the greatest effect of course being where there is the greatest absorption of the radiation.
  • a wave length should prefferably be chosen where the rays are most easily absorbed by the medium being conditioned, and it is to be noted for instance that for zinc oxide there is an absorption edge of somewhere about 1.28 angstrom units while for lead the effective edge would be at approximately .949 angstrom unit, in which case again X-rays which normally have a range from 0.1 to 100 angstrom units would be useful.
  • Gamma rays with an angstrom range of 0.0051.40 are similarly suitable with materials where there is an absorption edge within this range, but generally the shorter wave length requires a longer time element to effect the conditioning of the materials.
  • any electromagnetic wave can be used to condition materials prior to using them in xerographic processes, the particular wave length preferably being chosen according to where the greatest absorption of the radiation will result.
  • Example 1 Zinc oxide on bond paper backing, with coating comprising zinc oxide and 25% resin by weight, such as a linseed oil modified resin for example a short oil alkyd resin.
  • the coating is applied by known methods such as electrostatic coating.
  • This surface is exposed to light over its entire area, the light being that from 160 watt blue actinic lamp held 6 inches from the surface for 30 seconds.
  • Pentarol 20 is a phenol modified pentaerythritol ester of resin, acid value 7-15, specific gravity 1.09 at 20 C., melting range l10-l20 by Polymer Corporation Interstate Pty. Ltd.
  • Rhodene L6/ is a linseed oil modified alkyd resin oil length 52%, acid value 6-10, specific gravity 0.965 at 20 C. by Polymer Corporation Interstate Pty. Ltd.
  • the resultant image is characterized by a low contrast wide latitude, soft image, covering a density range of not less than 3.0, with minimum grain due to paper backing.
  • Example 3 Step 1. Use zinc oxide with 10% bismuth trioxide and then as in 1.
  • Example 4 As in Example 1, but expose to X-rays instead of light in step 4, for example to 140 kv. X-rays for two minutes through aluminum casting, the result is characterized by a radiograph of wide latitude and little paper grain.
  • Example 5 Use selenium, amorphous variety, vacuum evaporated on glass to 50 microns thickness.
  • step 2 expose for two seconds
  • step 4 expose for one second.
  • the result is characterized by soft tones, wide latitude and absence of flaws due to electrical exaggeration of defects at the interface.
  • Example 6 Use zinc oxide or selenium on a polyester film base without conductive substrate.
  • Example 1 The process is carried out as in Example 1 or 5. Result is production of a relatively conductive interface or substrate and a wide latitude picture without the normally encountered non-image patterns such as Lichtenberg figures and confusion zones.
  • the method of controlling contrast of a xerographic image which consists of the steps of first uniformly preexposing a photo-conductor surface to high intensity electromagnetic waves of a wave length which can be absorbed by the photo-conductor and to which the surface is sensitive whereby the photo-conductor is fatigued so that both its charge holding ability and its leakage rate is decreased, subsequently charging the thus fatigued photo-conductor in the absence of light by subjecting the photo-conductor to a corona discharge to produce a uniform electric charge on the photo-conductor, then exposing the photo-conductor to electromagnetic waves of the required pattern to differentially bleed away the charge and produce an electrostatic image, and then developing the electrostatic image by applying a developer which deposits according to the electrostatic pattern.
  • the electromagnetic waves are in the visible light range between about 4,000 to 7,000 angstrom units and the material being conditioned is a zinc oxide photo-conductor, the pre-exposure being to an electromagnetic wave in the light range between 4,000 to 7,000 angstrom units of effect equal to at least an intensity and duration of 1,130 candles per square foot acting for 30 seconds.
  • the electromagnetic waves are in the X-ray range between 0.1 and angstrom units and the material being conditioned is a zinc oxide photo-conductor, the pre-exposure eifect being equal to at least an intensity and duration from an X-ray tube at kv. at 12 inch spacing for ten milliampere-minutes.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Paper (AREA)
US128882A 1960-08-08 1961-08-02 Process for producing images in electrophotography and radiography Expired - Lifetime US3249430A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU63314/60A AU253042B2 (en) 1960-08-08 Improved process for producing images in electro-photography and electroradiography

Publications (1)

Publication Number Publication Date
US3249430A true US3249430A (en) 1966-05-03

Family

ID=3748160

Family Applications (1)

Application Number Title Priority Date Filing Date
US128882A Expired - Lifetime US3249430A (en) 1960-08-08 1961-08-02 Process for producing images in electrophotography and radiography

Country Status (6)

Country Link
US (1) US3249430A (en])
CH (1) CH387079A (en])
DE (1) DE1205828B (en])
FR (1) FR1369326A (en])
GB (1) GB963645A (en])
NL (1) NL267966A (en])

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3477846A (en) * 1967-05-01 1969-11-11 Gaf Corp Xerographic charge transfer process
US3533783A (en) * 1967-07-31 1970-10-13 Eastman Kodak Co Light adapted photoconductive elements
US3663225A (en) * 1969-04-04 1972-05-16 Itek Corp Photographic reflex process
US4175955A (en) * 1976-09-24 1979-11-27 Minolta Camera Kabushiki Kaisha Electrophotographic processes using a pre-exposure
US4288514A (en) * 1969-07-28 1981-09-08 Canon Kabushiki Kaisha Method for controlling image formation in electrophotography by pre-exposure step
US4464449A (en) * 1979-05-04 1984-08-07 Canon Kabushiki Kaisha Recording method having uniform exposure, charging, and infrared image exposure
US20100128847A1 (en) * 2008-11-27 2010-05-27 Postech Academy-Industry Foundation X-ray induced wettability modification

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6027026B2 (ja) * 1977-06-17 1985-06-26 キヤノン株式会社 電子写真方法及び装置
GB2058400B (en) * 1979-07-16 1983-12-07 Canon Kk Electrophotographic image forming apparatus

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2690394A (en) * 1943-08-27 1954-09-28 Chester F Carlson Electrophotography
US2741959A (en) * 1953-04-10 1956-04-17 Haloid Co Electrophotography
US2845348A (en) * 1952-01-04 1958-07-29 Kallman Hartmut Electro-photographic means and method
US2907674A (en) * 1955-12-29 1959-10-06 Commw Of Australia Process for developing electrostatic image with liquid developer
US2914403A (en) * 1955-05-17 1959-11-24 Rca Corp Electrostatic printing
US3041167A (en) * 1959-08-19 1962-06-26 Xerox Corp Xerographic process

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2901348A (en) * 1953-03-17 1959-08-25 Haloid Xerox Inc Radiation sensitive photoconductive member
US2937943A (en) * 1957-01-09 1960-05-24 Haloid Xerox Inc Transfer of electrostatic charge pattern

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2690394A (en) * 1943-08-27 1954-09-28 Chester F Carlson Electrophotography
US2845348A (en) * 1952-01-04 1958-07-29 Kallman Hartmut Electro-photographic means and method
US2741959A (en) * 1953-04-10 1956-04-17 Haloid Co Electrophotography
US2914403A (en) * 1955-05-17 1959-11-24 Rca Corp Electrostatic printing
US2907674A (en) * 1955-12-29 1959-10-06 Commw Of Australia Process for developing electrostatic image with liquid developer
US3041167A (en) * 1959-08-19 1962-06-26 Xerox Corp Xerographic process

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3477846A (en) * 1967-05-01 1969-11-11 Gaf Corp Xerographic charge transfer process
US3533783A (en) * 1967-07-31 1970-10-13 Eastman Kodak Co Light adapted photoconductive elements
US3663225A (en) * 1969-04-04 1972-05-16 Itek Corp Photographic reflex process
US4288514A (en) * 1969-07-28 1981-09-08 Canon Kabushiki Kaisha Method for controlling image formation in electrophotography by pre-exposure step
US4175955A (en) * 1976-09-24 1979-11-27 Minolta Camera Kabushiki Kaisha Electrophotographic processes using a pre-exposure
US4464449A (en) * 1979-05-04 1984-08-07 Canon Kabushiki Kaisha Recording method having uniform exposure, charging, and infrared image exposure
US20100128847A1 (en) * 2008-11-27 2010-05-27 Postech Academy-Industry Foundation X-ray induced wettability modification
US8497000B2 (en) * 2008-11-27 2013-07-30 Postech Academy-Industry Foundation X-ray induced wettability modification

Also Published As

Publication number Publication date
GB963645A (en) 1964-07-15
NL267966A (en])
CH387079A (fr) 1965-01-31
DE1205828B (de) 1965-11-25
FR1369326A (fr) 1964-08-14

Similar Documents

Publication Publication Date Title
US3041167A (en) Xerographic process
US3457070A (en) Electrophotography
US3615395A (en) Electrostatic and electrophotographic variable contrast image-forming methods
US3249430A (en) Process for producing images in electrophotography and radiography
US3475170A (en) Methods of electrophotographic and electrostatic recording
US3685989A (en) Ambipolar photoreceptor and method of imaging
US3406063A (en) Xerographic material containing an inorganic photoconductor and nonpolymeric crystalline organic substances and methods of using of such material
US4897333A (en) Copying method
US3712810A (en) Ambipolar photoreceptor and method
US2940848A (en) Photoconductive layer for recording element and method of producing same
US3873310A (en) Method of controlling the brightness acceptance range and tonal contrast of a xerographic plate
US2986467A (en) Photoconductive layer for recording element and method of producing same
JPS6238491A (ja) 感光体の除電方法
US4420547A (en) Photosensitive member for electrophotography having ultraviolet absorption layer
US3540885A (en) Reduction of fog formation in an electrophotographic light sensitive sheet
US3414409A (en) Particle transfer
US3655369A (en) Persistent internal polarization process in electrophotography
US3909254A (en) Laser recording method
US4170476A (en) Layered photoconductive element having As and/or Te doped with Ga, In or Tl intermediate to Se and insulator
US3003869A (en) Xerographic plate of high quantum efficiency
US3930853A (en) Accelerating aging method for selenium-arsenic photoconductors
US3645729A (en) Method of transferring electrostatic latent images using multiple photoconductive layers
US2856535A (en) Increasing speed in xeroradiography
US3975635A (en) Xeroradiographic plate
US3095301A (en) Electrophotographic element