US3490903A - Alloys of antimony and selenium used in photoconductive elements - Google Patents

Alloys of antimony and selenium used in photoconductive elements Download PDF

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Publication number
US3490903A
US3490903A US566593A US3490903DA US3490903A US 3490903 A US3490903 A US 3490903A US 566593 A US566593 A US 566593A US 3490903D A US3490903D A US 3490903DA US 3490903 A US3490903 A US 3490903A
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Prior art keywords
selenium
antimony
percent
vitreous
plate
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US566593A
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English (en)
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Mark B Myers
James W Sparks
Evan J Felty
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Xerox Corp
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Xerox Corp
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    • 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, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
    • G03G5/082—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and not being incorporated in a bonding material, e.g. vacuum deposited

Definitions

  • a photoconductive insulating layer comprising a vitreous alloy of antimony and selenium, with the antimony being present in a concentration of from about 5 to 25 percent and the method of imaging a xerographic plate containing the antimony-selenium composition.
  • This invention relates in general to the art of xerography, and in particular, to a new photosensitive element.
  • a member or plate which comprises a conductive backing such as, for example, a metallic surface having a photoconductive insulating layer thereon.
  • a suitable plate for this purpose is a metallic member having thereon a layer of vitreous selenium.
  • Such a plate is characterized by being capable of receiving a satisfactory electrostatic charge and selectively dissipating such a charge when exposed to a light pattern and, in general, is largely sensitive to light in the bluegreen spectral range.
  • vitreous selenium for the most part has become the standard in commercial xerography, many of its properties can be improved by the addition of alloying; elements which enhance such properties as spectral response, light sensitivity, photoconductive stability, etc.
  • vitreous selenium shows a satisfactory sensitivity
  • the need for photoconductors exhibiting increased sensitivity and spectral response exceeding those of vitreous selenium is needed in high speed processes which require plates having a very high degree of sensitivity due to the short time factor in rapid cycling.
  • a vitreous alloy of antimony and selenium in an effective range of about 5 to 21 percent by weight antimony, with the remainder substantially selenium yields a photosensitive composition having a sensitivity factor (to be more fully described later) up to 12 times greater than that of vitreous selenium, and in addition having a relative response up to three times that of vitreous selenium in the blue-green spectral range.
  • a preferred range of about 7 to 19 percent antimony yields the greatest sensitivity factor while, at about 14 percent antimony the maximum sensitivity of a factor of 12 is reached.
  • Percentages of antimony less than about 5 percent and more than about 21 percent yield no increase in sensitivity or spectral response over that of substantially pure vitreous selenium.
  • FIGURE 1 is a graphical illustration of the sensitivity factor of vitreous selenium as compared with various percentages of antimony, and selenium as contemplated by this invention.
  • FIGURE 2 is a graphical illustration of the relative response of the antimony-selenium alloys contemplated by this invention as compared with vitreous selenium.
  • the antimony-selenium vitreous alloys of this invention may be prepared by any suitable techniques. Typical techniques are co-evaporation, wherein the appropriate amount of selenium and antimony are each separately placed in heated crucibles maintained in a vacuum chamber under any suitable vacuum conditions such as from about 2X10- to 2x10 millimeters of mercury.
  • the crucibles may be made of any inert material such as quartz or ceramic lined metal.
  • the selenium and antimony are each maintained at a temperature between about their respective melting points and boiling points.
  • a temperature of about 290 C. for selenium, and 660 C. for antimony was found sufiicient.
  • the temperature of the antimony containing crucible would be increased and/ or the temperature of the selenium containing crucible lowered.
  • the temperature changes would be reversed.
  • the evaporation temperature of one or both of the components may be maintained at a temperature below their melting point.
  • a film thickness of about 10 to 40 microns is obtained when evaporation is continued for a time ranging from about 1 to 3 hours at a vacuum of about 5 X 10- mm. of mercury.
  • a substrate is supported above the heated crucibles upon which the antimony and the selenium are co-evaporated.
  • a suitable substrate temperature is from about 50 to C.
  • Another typical method includes flash evaporation under vacuum conditions similar to those defined in coevaporation, wherein an alloy of selenium and antimony having a particle size of about less than about 0.1 mm. in diameter is selectively dropped into a heated inert crucible maintained at a temperature of about 450 to 550 C. The vapors formed by the heated mixture are evaporated upward onto a substrate supported above the crucible. The substrate is maintained at a temperature of about 50 to 70 C. This procedure is continued until 3 the desired thickness of the vitreous antimony-selenium alloy has been formed on the substrate.
  • the alloys of this invention may be conveniently formed on any conductive substrate.
  • This may be a conventional metal plate such as brass, aluminum, gold, platinum, steel or the like.
  • the support member may be of any convenient thickness, rigid or flexible, in the form of a sheet, a web, a cylinder, or the like and may be coated with a thin layer of plastic. It may also comprise such materials as metallized paper, plastic sheets covered with a thin coating of aluminum or copper iodide, or glass coated with a thin layer of chromium or tin oxide. In certain cases, the substrate may even be dispensed with, if desired.
  • the thickness of the antimony-selenium vitreous alloy layer for use as a photoconductor is not critical.
  • the layer can be as thin as a micron, or as great as 300 microns or more, but for most applications the thickness will generally be about 20 to 80 microns.
  • EXAMPLE I An alloy of about 20 percent antimony and 80 percent selenium is ground in a ball mill and then placed in a brass hopper containing a copper chute adapted to deliver particles, up to 0.1 cm. in diameter, into a quartz crucible maintained below said hopper.
  • the quartz crucible is surrounded with a resistance heater controlled to heat the crucible to a temperature of about 490 C.
  • An aluminum substrate placed on a base and maintained at a temperature about 55 C. is positioned about 12 inches above the quartz crucible.
  • a bell jar is then placed over the hopper, crucible, and substrate, and evacuated to a vacuum of about 5 10 millimeters of mercury, and the quartz crucible heated to a temperature of 490 C.
  • the quartz crucible When the quartz crucible is brought to 490 C. the hopper door below the chute leading to the quartz crucible is opened allowing a small sample of the antimony-selenium mixture to pour into the quartz crucible.
  • the antimonyselenium mixture rapidly evaporates causing vapors of antimony and selenium to come into contact with the suspended aluminum substrate. This process is continued for about 2 hours at which time a 15 micron layer of antimony-selenium containing about 20 percent antimony has been formed on the aluminum substrate.
  • the crucible is then allowed to cool to room temperature, the vacuum broken, and the coated substrate removed from the vacuum chamber.
  • a 40 micron film of vitreous antimony-selenium on a NESA substrate containing about 10 percent antimony and 90 percent selenium is prepared by placing 20 gm. samples of antimony and selenium in the form of pellets into separate quartz crucibles. The quartz crucibles are placed into a vacuum chamber which is evacuated to'a vacuum of about 5X10 millimeters of mercury. A substrate of NESA glass is suspended about 12 inches above the quartz crucibles and maintained at a temperature of about 55 C. The antimony and selenium are co-evaporated onto the NESA substrate by maintaining the temperature of the selenium crucible at about 290 C. and the temperature of the antimony crucible at about 602 C. by means of resistance heating elements. The quartz crucibles containing the antimony and selenium samples are maintained at these temperatures for about 1 hours at which time the evaporation is complete. The crucibles.
  • the vitreous-selenium coated plate formed by the method of Example II is then imaged as follows in a xerographic mode:
  • the plate is corona charged to a positive potential of about 300 volts, and then exposed to a watt tungsten light source at a distance of about 16 inches for about 2 seconds to form a latent electrostatic image on the surface of said plate.
  • the latent image is then developed by cascading electroscopic marking material across the surface containing said image.
  • the image is transferred to a sheet of paper and heat fused to make it permanent. A good quality copy of an original is obtained by this method.
  • Example IV The vitreous-antimony selenium coated plate of Example I is imaged by the method set forth in Example III. A Xerox 914 Green Lamp is used in place of the tungsten light source. A good quality image is obtained.
  • a series of antimony-selenium alloys were prepared by the method set forth in Example II, and compared with a standard test plate of vitreous selenium such as those shown by U.S. Patent 2,970,906 to Bixby. Both the antimony-selenium plates, and the selenium plates contained a layer of about 40 to 50 microns of the respective photoconductive layers on an aluminum substrate. Both groups of plates were compared for their sensitivity factor and relative spectral response as illustrated in FIGURES 1 and 2, respectively.
  • FIGURE 1 antimony-selenium plates of varying compositions and thicknesses were tested by the electrostatic contrast potential scanner in order to determine their speeds relative to selenium under given (Xerox 2400 Machine) conditions.
  • the relative speed is illustrated by the sensitivity factor; a factor of 2 meaning that the particular alloy is 2 times faster or more sensitive than selenium.
  • the plate is run through a cycle consisting of corona charging the plate to a constant field of twelve volts per micron (12 v./;:.), exposing the plate to reflected light measuring the potential on the plate by means of an electrometer, and then erasing all residual voltage by means of a cool white fluorescent lamp.
  • the plate is first exposed using light reflected from a white background with the exposure aperture varying logarithmically (3 /2) for twelve consecutive cycles. The plate is again run through the same cycles; however, this time the exposure light is reflected from a grey subject. A potential difference is then calculated between the areas discharged by the light reflected from the white and grey subjects. The point at which this potential difference is the greatest is then compared to selenium under the same conditions and this gives a relative speed with respect to the selenium standard.
  • the light source used in a Xerox 914 fluorescent green lamp The residual voltage is erased by a cool white fluorescent lamp.
  • the potential is measured by a Monroe 1264-4 dual electrometer follower, with a brush, Mark 280, dual channel strip chart recorder.
  • the addition of antimony to selenium increases the sensitivity from a factor of 2 at about 6.0 percent to a factor of 12 times that of selenium at about 14 percent antimony.
  • FIGURE 2 the relative response of various percentages of antimony and selenium as compared with 100 percent selenium is illustrated at four different wavelengths. The relative response is based on a factor of 1.0 for 100 percent vitreous selenium at a wavelength of 0.40 micron.
  • the relative response is measured by first positively charging the plates under dark room conditions to a field of 12 volts per micron by corona discharge. The potential is measured by an electrometer probe. The plates are then discharged by monochromatic radiation from a Burton lamp which is a 100 watt tungsten lamp Model 1200, using Corning filters to give the appropriate wavelength as illustrated by the graph. Monochromatic radiation of 0.40, 0.50, 0.60 and 0.70 microns was used. At each particular wavelength the initial rate of discharge (loss of voltage per unit time) for the 100 percent selenium plate was measured against various antimony-selenium alloys. The relative response is measured as the ratio of the initial discharge rate of the antimony-selenium alloy to the 100 percent vitreous selenium based on selenium at 0.40 microns. The rate of discharge is measured with an electrometer.
  • a photosensitive element having a photoconductive insulating layer, said layer comprising a vitreous alloy of antimony and selenium with the antimony comprising between about 5 to 21 percent of said layer.
  • a xerographic plate having an electrically conductive support member and a photoconductive insulating layer thereon, comprising a vitreous alloy of antimony and selenium, with the antimony comprising between about 5 to 21 percent of said layer.
  • a method of imaging comprising:
  • a xerographic plate having an electrically conductive support member and a photoconductive insulating layer thereon, comprising a vitreous alloy of antimony and selenium, with the antimony comprising between about 5 to 21 percent of said layer;
  • a method of imaging comprising:
  • a xerographic plate having an electrically conductive support member and a photoconductive insulating layer thereon, comprising a vitreous alloy of antimony and selenium, with the antimony comprising between about 5 to 21 percent of said layer;

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
US566593A 1966-07-20 1966-07-20 Alloys of antimony and selenium used in photoconductive elements Expired - Lifetime US3490903A (en)

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US56659366A 1966-07-20 1966-07-20

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US3490903A true US3490903A (en) 1970-01-20

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US (1) US3490903A (de)
DE (1) DE1597872B2 (de)
GB (1) GB1185389A (de)
NL (1) NL159201B (de)
SE (1) SE318193B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3867143A (en) * 1969-01-17 1975-02-18 Canon Kk Electrophotographic photosensitive material
US3887368A (en) * 1966-05-16 1975-06-03 Xerox Corp Composition
US3973960A (en) * 1973-02-03 1976-08-10 Licentia Patent-Verwaltungs-G.M.B.H. Electrophotographic element having a selenium layer containing arsenic in varying concentrations across the layer thickness
US4049505A (en) * 1974-10-14 1977-09-20 Chatterji Arun K Photoconductors for electrostatic imaging systems
US4097277A (en) * 1973-01-31 1978-06-27 Canon Kabushiki Kaisha Photosensitive member having layer of vinyl carbazole polymer containing antimony chalcogen compound of antimony and sulfur

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297691A (en) * 1939-04-04 1942-10-06 Chester F Carlson Electrophotography
US2910602A (en) * 1956-07-24 1959-10-27 Emi Ltd Light sensitive devices
US2962376A (en) * 1958-05-14 1960-11-29 Haloid Xerox Inc Xerographic member

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297691A (en) * 1939-04-04 1942-10-06 Chester F Carlson Electrophotography
US2910602A (en) * 1956-07-24 1959-10-27 Emi Ltd Light sensitive devices
US2962376A (en) * 1958-05-14 1960-11-29 Haloid Xerox Inc Xerographic member

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3887368A (en) * 1966-05-16 1975-06-03 Xerox Corp Composition
US3909458A (en) * 1966-05-16 1975-09-30 Xerox Corp Photosensitive vitreous layer comprising bismuth and selenium
US3867143A (en) * 1969-01-17 1975-02-18 Canon Kk Electrophotographic photosensitive material
US4097277A (en) * 1973-01-31 1978-06-27 Canon Kabushiki Kaisha Photosensitive member having layer of vinyl carbazole polymer containing antimony chalcogen compound of antimony and sulfur
US3973960A (en) * 1973-02-03 1976-08-10 Licentia Patent-Verwaltungs-G.M.B.H. Electrophotographic element having a selenium layer containing arsenic in varying concentrations across the layer thickness
US4049505A (en) * 1974-10-14 1977-09-20 Chatterji Arun K Photoconductors for electrostatic imaging systems

Also Published As

Publication number Publication date
NL159201B (nl) 1979-01-15
NL6709986A (de) 1968-01-22
GB1185389A (en) 1970-03-25
DE1597872B2 (de) 1976-02-12
SE318193B (de) 1969-12-01
DE1597872A1 (de) 1970-09-17

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