US3003870A - Alteration of characteristic curve of zinc oxide electrophotographic materials - Google Patents

Alteration of characteristic curve of zinc oxide electrophotographic materials Download PDF

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US3003870A
US3003870A US653316A US65331657A US3003870A US 3003870 A US3003870 A US 3003870A US 653316 A US653316 A US 653316A US 65331657 A US65331657 A US 65331657A US 3003870 A US3003870 A US 3003870A
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zinc oxide
sensitivity
specks
particulate
coatings
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James G Jarvis
Dale L Smith
Rayen W Tyler
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Eastman Kodak Co
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Eastman Kodak Co
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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
    • G03G5/09—Sensitisors or activators, e.g. dyestuffs

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  • This invention relates to electrophotography, and more particularly, to a means of altering the sensitivity characteristics of an electrophotographic material containing zinc oxide as the photoconductive ingredient.
  • zinc oxide can be dispersed in an insulating material, such as various synthetic resins of the polyvinyl type, waxy materials (e.g., paraffin, etc), etc, and this material coated on a conducting support, e.g., paper (sufliciently conducting at relative humidities above 30%).
  • a conducting support e.g., paper (sufliciently conducting at relative humidities above 30%).
  • the resulting photographic element can then be given a blanket negative charge by placing the same under a corona discharge which serves to give a more or less uniform negative charge to the surface of the photoconductive layer.
  • the negative charge leaks away roughly in proportion to the quantity of light falling upon that area of the surface of the photoconductive layer.
  • the exposed material can then be treated with a developer containing a powder or toner on a granular carrier, e.g., iron filings, the powder being. attracted to those portions of the photoconductive layer which still retain an electrostatic charge.
  • a low-melting solid. for one of the constituents of the powder, it is possible to treat the developed photoconductive material with heat and cause the powder to adhere permanently to the surface of the photoconductive layer.
  • This method has been described as being somewhat similar to the process known as xerography, although it will be noted that the photoconductive layer itself provides the final print as distinguished from the xerographic process wherein the original photoconductive surface is used as a transfer plate to transfer the developed image to a separate receiving sheet. See RCA Review, vol. (1954), pages 469-484.
  • the zinc oxide customarily employed in the above process has sensitivity from about 325 to 410 mp, although its sensitivity can be extended considerably by special treatments with carbon dioxide or ammonia, or by sensitizing with a spectral sensitizing dye, such as Rose Bengal, iluorescein, cyanine dyes, etc.
  • a spectral sensitizing dye such as Rose Bengal, iluorescein, cyanine dyes, etc.
  • zinc oxide which may or may not have been treated to extend its light absorption range gives an H and D curve having rather steep gradation so that the exposure scale is generally no more than about 0.8 Log E unit (depending upon toner used as developer, etc.).
  • an object of our invention to'provide an electrophotographic material having, an exposure scale considerably broader than the customarily employed electrophotographic materials comprising zinc oxide.
  • Another object or our invention is to provide an electrophotographic material showing varying degrees of contrast, depending upon the spectral distribution of the exposing source.
  • Still another object is to provide zinc oxide electrophotographic papers, the surface of which is sensitive to various regions of the spectrum.
  • surface layer is continuous, although in the instant in-.
  • the first method comprises treating the surface of a' zinc oxide photoconductive layer as described in greater detail hereinafter with a pattern of specks of a zinc oxide dispersion having a sensitivity difierent from that of the uniformly sensitive lower layer.
  • This difierence in sensitivity may be a dilferent level of sensitivity, to the same region of the spectrum as the lower layer, or it may be a sensitivity in a different region of the spec trum.
  • the lower continuouslayer may be green sensitive, while the pattern of specks may have its maximum sensitivity in the red region of the spectrum.
  • the lower layer may have its sensitivity in the green region of the spectrum, while the pattern of specks. may have a different level of green sensitivity.
  • Another means of providing the novel com positions of our invention is to sensitize by means of a non-wandering dye, a zinc oxide dispersion and this sensitized dispersion intimately with another zinc oxide dispersion which may or may not have been Sensitized (its sensitivity being different from that of the our invention is dependent upon three variables, which are:
  • FIGURE 1 is a diagrammatic sketch of the characteristic curve of a typical electrophotographic material prepared according to prior art methods. 7 g
  • FIGURE 2 shows the characteristic curve of ail electrophotographic material obtained according to our invention upon exposure of this material to red illumination.
  • FIGURE 3 illustrates the characteristic curve ofan electrophotographic material obtainable according to our invention and shows the elfect ofexposure of this material to red or green illumination.
  • FIGURE 4 illustrates the characteristic curve of the same material shown in FIGURE 3', the ratio of red green illumination being adjusted,- as described more fully, below. 7 7
  • FIGURE 5 illustrates the sensitometr'ic' properties of the material obtained according to Example 1 below, as compared with uniformly sensitized electropho'tographic material.
  • FIGURE 6 illustrates the relationship between speck coverage and integrated density, as described in more detail below, and
  • FIGURE 7 illustrates a family ofcliaract'eristic curves wherein the speck coverage is varied as described in more detail below.
  • the background and specks have their sensitivity lying in the same region of the spectrum, both have generally been sensitized by means of a spectral sensitizing dye as described in more detail below.
  • the background and specks will have a sensitivity differing from one another on the order of about 6 to 8 times as a maximum to about 1% times as a minimum. That is, the sensitivities of the two areas will differ from one another on the order of not more than about 0.8 Log E unit and not less than about 0.1 Log E unit. This means that the shoulder of the characteristic curve of one area will correspond approximately to the toe of the characteristic curve of the other material for the maximum case.
  • the percentage of area covered by the specks should vary between about 2 and 98 percent, based on the total area of the photoconductive surface.
  • the specks can vary in number from about 10 to 300 per square inch. This corresponds roughly to a halftone screen ruling from about 10 lines per inch, such as might be used for billboard posters, to about between 200 and 300 lines per inch for high quality reproduction. While the foregoing applies primarily to coatings prepared by applying a pattern of specks to a continuous photoconductive coating, so that the material can be said to be composed of a background area and an area of specks, it is to be understood that similar characteristics are necessary where the photoconductive surface is prepared from a mixture of two or more zinc oxide dispersions having different sensitivities.
  • Cyanine dyes (9) 3,3-diethyl-4,5,4,5'-dibenzothiacyanine chloride 10) 3-B-carboxyethyl-1'-ethyl 6' methoxy 5 phenylthia-2'-cyanine iodide (11) 3,3'-diethyl-4,5,4',5'-dibenzoxacyanine iodide (12) 3,3'-diethylthiazolinocarbocyanine iodide (13) 3,3'-diethyloxacarbocyanine iodide (14) 3,3'-diethyl-9-methyloxaselenacarbocyanine 1od1de Typical dyes for conferring sensitivity in the red region of the spectrum are:
  • Dicarbocyanine dyes (15) 3,3-di-B-hydroxyethylthiadicarbocyanine bromide (16) Anhydro 3,3'-di-13-carboxyethylthiadicarbocyanine hydroxide (17) 3,3'-diethyloxathiadicarbocyanine 1od1de D (18) 3,3-diethyl-4,5,4',5-dibenzothiadicarbocyanme 1odide (19) 3'-carboxymethy1-3-ethyloxathiadicarbocyanine iodide (20) 3-carboxymethyl-3-ethyloxathiadicarbocyanine iodide (21) 3,3-di(carboxymethyl)oxathiadicarbocyaniue bromide B.
  • Carbocyanine dyes (22) 3,3'-diethyl 9 methyl-4,5,4',5-dibenzothiacarbocyanine chloride (23) Anhydro-3,3 di ,8 carboxyethyl-5,5-dichloro-9- ethylthiacarbocyaniue hydroxide (124) Anhydro 3 ,B carboxyethyl-S,5'-dichloro-9-ethyl- 3- 3-sulfoethylthiacarbocyanine hydroxide (25) 9-ethyl-3,3-di-,8-hydroxyethy1thiacarbocyanine 1odide C.
  • FIGURE 1 the characteristic curve of a typical zinc oxide coating which has been made green sensitive.
  • FIGURE 1 shows that the maximum density obtainable with such material is 1.2 when developed with a typical toner, while its exposure scale covers only 0.8 Log E unit.
  • the photoconductive material in FIGURE 1 consists of a continuous layer having more or less uniform sensitivity. Each part of the surface area of such a sheet is then covered with a pattern of specks having red sensitivity and occupying approximately 20.3 percent of the surface area. A material is obtained having the characteristic curve shown in FIGURE 2, if the material is exposed to red illumination.
  • the red sensitive specks have become completely discharged, while the green sensitive areas of the background have lost no charge and can still be developed to a micro maximum density of 1.2. Since the red sensitive specks occupy 20.3 percent of the surface area, the sample will have an integrated reflectance of about 25 percent, corresponding to a macro or integrated density of about 0.6. Of course, by controlling the percentage of area covered y he specks, the density of region A can be placed at any desired level.
  • FIGURES l to 4 are diagrammatical, they are typical for the process, and it can be seen that the exposure scale of the paper has been doubled, while the gamma or contrast has been halved.
  • the sample can be illuminated by a mixture of red and green light. This can easily be obtained from an incandescent light source filtered by magenta and cyan color compensating filters. Inasmuch as the red and green sensitive areas shown in the characteristic curves of FIGURES 1 to 4 are also sensitive to ultraviolet radiation, and about equally so, the ultraviolet component should be filtered out if maximum exposure scale is to be obtained.
  • exposing the material illustrated in FIGURES 1 to 4 by ultraviolet radiation alone a curve shape similar to that of FIGURE 1 can be obtained.
  • any curve between FIGURES 1 and 4 can be obtained.
  • EXAMPLE 1 100 parts of powdered zinc oxide were mixed with 20 parts of a high styrene content styrene-butadiene resin sold commercially as Pliolite S-7 (Goodyear Rubber & Tire Co.) and sufficient toluene added to the viscous dispersion to give 50 percent in total solids. Rose Bengal (0.02 part) was added to the viscous solution which was then coated on a photographic paper base (baryta coated). The toluene was then evaporated from the coating to give a photoconductive layer comprising zinc oxide, binder and sensitizing dye. It was green sensitive.
  • Pliolite S-7 Goodyear Rubber & Tire Co.
  • a second dispersion of zinc oxide was prepared exactly as described above, except that 0.01 part of 3,3'-di(fihydroxyethyl)thiadicarbocyanine bromide was used as the sensitizing dye in place of the Rose Bengal.
  • the dispersion was then diluted with toluene to 22.5 percent in total solids and this. dispersion sprayed by a few rapid passes. of a finely-adjusted, spray gun onto the surface of the dried photoconductive coating.
  • the amount of dispersion laid. down was. estimated by weighing.
  • the speck size was found to be approximately 0.1 to 0.2 mm., while the amount of specks added was about 0.10 g./square foot, corresponding to an area coverage of 20.3 percent.
  • the solvent. was then evaporated. from the speck areas of the coating.
  • FIGURE of the accompanying drawings The eltect of exposing the above photoconductive paper is illustrated in FIGURE of the accompanying drawings.
  • Curve 1 of FIGURE 5 illustrates the characteristic curve obtainedfor this material using only ultraviolet radiation for the exposure.
  • ex.- posure was made through a Wratten No. 18A filter, i.e., a filter transmitting radiation only between about 285 and 405 m
  • Curve 3 of FIGURE 5 illustrates the characteristic curve obtained for this material when exposure is made to 3000- K. tungsten illumination filtered by a Kodak, Wratten; filter No.
  • EXAMPLE 2 An electrophotographic paper having performance characteristics similar to the paper described in Example 1 above was prepared by spraying the red sensitive specks on a green sensitive support layer which was prepared by the following method:
  • EXAMPLE 3 100 parts of powdered zinc oxide were mixed with 20 parts of a high styrene content styrene-butadiene resin of the type used in Example 1 above, and suflicient toluene was added to produce a dope containing 50 percent in total solids. This dope was then coated on an ordinary photographic paper support containing a conventional baryta layer. The toluene was then evaporated fromthe coating.
  • the electrophotographic paper prepared in this man.- ner was found to have an exposure scale of about 1.3 Log E units compared with a uniformly sensitive, unsensitized layer having an exposure scale of about 0.7 Log E unit.
  • the unsensitized layer had normal sensitivity to ultraviolet iilumination, while the pattern of specks was sensitive both to ultraviolet and green illumination. By varying the ratio of ultraviolet to green illumination, it was possible to produce a large variety of curve shapes.
  • Unfiltered tungsten illumination of 3000 K. was found to provide a useful ultraviolet-green ratio giving the desired exposure scale of 1.3 Log E units. Variations in the ultraviolet-green ratio can be made using a Kodak Wratten filter No. 8 and a Kodak Wratten filter such as No. 18A, which transmits radiation only between about 285 and 405 m the filters being superposed on separate tungsten light sources in order to control. mixing.
  • EXAMPLE 4 A layer of green sensitive zinc oxide was prepared exactly as described in Example 1 above, this coating con taining about 0.02 part of Rose Bengal. This composition was then coated on an ordinary photographic paper support containing the conventional ba'ry-ta layer. A second. green sensitive zinc oxide dispersion was prepared as follows:
  • Another type of coating similar to that of Example 4, comprises an ultraviolet sensitive zinc oxide layer coated with specks of a dispersion having a dilferent ultraviolet sensitivity.
  • the difference in ultraviolet sensitivity can be obtained by dyeing the binder in either the support layer or the specks with an ultraviolet absorbing dye of the type illustrated in Sawdey U.S. Patent 2,739,888, issued March 27, 1956.
  • either region could also contain a spectral sensitizing dye, preselected to give different sensitivity in the background and speck portions of the coatings but the sensitivity in the specks and the background should have the same relative values (i.e., ratio of ultraviolet to sensitized) throughout the ultraviolet and visible spectrum so that such a coating is invariant with respect to the spectral quality of the illuminant and can be manufactured in specified contrast grades.
  • a spectral sensitizing dye preselected to give different sensitivity in the background and speck portions of the coatings but the sensitivity in the specks and the background should have the same relative values (i.e., ratio of ultraviolet to sensitized) throughout the ultraviolet and visible spectrum so that such a coating is invariant with respect to the spectral quality of the illuminant and can be manufactured in specified contrast grades.
  • EXAMPLE An unsensitized zinc oxide dispersion was prepared exactly as described in Example 3 above and 5 parts of this unsensitized dispersion was mixed with 1 part of a green sensitive zinc oxide dispersion prepared according to Example 4 above, this dispersion containing 0.01 part of Rose Bengal as the green sensitizer. The mixed dispersions were then coated out onto an ordinary photographic paper support having a baryta layer. After removal of the toluene by heating, the exposure scale of the resulting paper was extended, compared with a similar material which had been uniformly sensitized.
  • a spectral sensitizing dye having non-wandering properties such dyes generally containing a long-chain alkyl group.
  • Typical of such non-wandering dyes which can be usefully employed is 5-[ (3-ethy1-2( 1H) -a-naphthothiazolylidene) ethylidene] -3 -n-hep tyll-phenyl-Z-thiohyd antoin.
  • sensitizing dye such as by letterpress or lithography, silk screen, gravure, etc. Under such conditions, care should be taken to avoid diffusion of the dye away from the area to which it is originally applied.
  • the maximum density of the process is 1.20, corresponding to a reflectance of 6.3 percent, while the minimum density (the paper being substantially completely discharged) is 0.10 corresponding to a reflectance of 79.3 percent. It can be safely assumed that the specks become completely dis charged (corresponding to a micro minimum density of 0.10) while the remaining areas are still fully charged (corresponding to a micro maximum density of 1.20). If the surface area (uniformly sensitized) is then covered to the extent indicated above, i.e., between 2 and 98 percent, with sensitivity specks, the corresponding integrated densitiescan be tabulated as follows:
  • FIGURE 7 the efiect of coverage from 2 to 98 percent on the characteristic curve of the original material is shown diagrammatically.
  • curve A of FIGURE 7 only two percent of the area is covered by specks having a sensitivity different from the background, giving a long shoulder to the characteristic curve.
  • Curve B shows a corresponding material but the coverage of the specks is 70 percent, giving a curve having a long toe.
  • the specks are exposed in such a way that they appear to be faster than the background.
  • the same curves could be obtained for about 98 percent and 30 percent coverages, respectively.
  • sensitizing dyes in our invention which are characterized by their non-wandering properties. See Example 5 above.
  • Such dyes generally contain an alkyl group having at least 7 carbon atoms and a group of such dyes have been previously described in U.S. Patent 2,282,116. Other examples of such dyes can be found in additional patents, domestic and foreign.
  • Typical driers include lanthanum naphthenate, cerium naphthenate, zirconium naphthenate, cobalt naphthenate, lead naphthenate, lanthanum 2-ethylhexoate, cerium 2-ethylhexoate, etc., these metallic driers being used alone or in admixture with one another. These metallic driers are particularly useful in treating resinous binders, such as drying oil-modified styrene alkyd resins, silicone alkyd resins, etc.
  • An electrophotographio element comprising a con tinuous" coating on a conductive snpport of particulate photoconductive zinc oxide (1') having a given sensitivity, dispersed in an insulating binder-material, and coated over said continuous coating a discontinuous coating comprising small spots of substantially,- uniformly-distributed insulating binder-material containing particulate photoeonductive zinc oxide (II) having a ditferent givenflsensitivity, said particulate photoconductive zinc oxide (1) and said particulate photoconductive zinc oxide (II) having sensitivity in the same spectral region; but one of said particulate photoconductive zinc oxides having a sensitivity of from.
  • An electrophotographic element comprising a continuous coating on a conductive support of part u'late photoconductive zinc oxide (I) having a given sensitivity, dispersed in an insulating binder-material, and coated over said continuous coating a discontinuous coating comprising small spots of substantially, uniformly-distributed insulating bindernnaterial containing particulate photoconductive zinc oxide (II) having a different given sensitivity, said particulate photoconductive zinc oxide (I) and said particulate photoconductive zinc oxide (II) having sensitivity in dififerent spectral regions and one of said particulate photoconductive zinc oxides having a sensitivity lying beyond about 410 mu, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly-distributed insulating binder-material containing particulate photoconductive zinc oxide (II), the number of said small spots being between 10 and $00 per square inch, the said insulating binder-materials of said coatings being of such nature that said coatings
  • An electrophotographic element comprising a continuous coating on a conductive support of particulate photoconductive zinc oxide (I) having a given sensitivity, dispersed in an insulating polyvinyl resin, and coated over said continuous coating a discontinuous coating comp1ising small spots of substantially, uniformly-distributed insulating polyvinyl resin containing particulate photoconductive zinc oxide (II) having a different given sensitivity, said particulate photoconductive zinc oxide (I) and said particulate photoconductive zinc oxide (II) having sensitivity in the same spectral region, but one of said particulate photoconductive zinc oxides having a sensitivity of from 1% to 8 times that of the other of said particulate photoconductive zinc oxides, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly-distributed insulating polyvinyl resin containing particulate photoconductive zinc oxide (II), the number of said small spots being between 10 and 300 per square inch, the said insulating polyvinyl resins of
  • An electrophotographic element comprising a continuous coating on a conductive support of particulate photoconductive zinc oxide (I) having a given sensitivity, dispersed in an insulating polyvinyl resin, and
  • An elect-rophotog'raphic element comprising a eontinuous coating on a conductive support of particulate photoconductive zinc oxide (I) having a. given sensitivity, dispersed in an insulating polyvinyl resin, and coated over said continuous coating a disont'inuous coating campus ing small spots of substantially, uniformly-distributed insulating polyvinyl resin containing particulate photoconductive zinc oxide (II) having a diiferent given sensitivity, one of said particulate z'inc oxides having sensitivity only in the red region of the visible spectrum and the other of said particulate zinc oxides having sensitivity only in the green region of the visible spectrum, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly distributed insulating polyvinyl resin containing particulate photoconductive zinc oxide (II), the number of said small spots being between 10 and 300 per square inch, the said insulating polyvinyl resins of said coatings being of such nature that said coatings
  • An electrophotographic element comprising a continuous coating on a conductive support of particulate photoconductive zinc oxide (I) having a given sensitivity, dispersed in an insulating polyvinyl resin, and coated over said continuous coating a discontinuous coating comprising small spots of substantially, uniformly distributed insulating polyvinyl resin containing particulate photoconductive zinc oxide (II) having a different given sensitivity, one of said particulate photoconductive zinc oxides having sensitivity only beyond the blue region in the visible spectrum and the other of said particulate photoconductive zinc oxides being unsensitized, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly distributed insula ing polyvinyl resin containing particulate pliotoconductive zinc oxide (II), the number of said small spots being between 10 and 300 per square inch, the said insulating polyvinyl resins of said coatings being of such nature that said coatings have a low decay rate in the dark when said coatings have received an electrostatic charge.
  • sensitized photoconductive zinc oxide particles are sensitized with a merocyanine dye having an alkyl group containing at least 7 carbon atoms attached to the carbonylic oxygen-containing nucleus of said merocyanine dye.
  • An electrophotographic element comprising a continuous coating on a paper support of particulate photoconductive zinc oxide (1) having a given sensitivity, dispersed in an insulating binder-material, and coated over said continuous coating a discontinuous coating comprising small spots of substantially, uniformly-distributed insulating binder-material containing particulate photoconductive zinc oxide (II) having a different given sensitivity, said particulate photoconductive zinc oxide (I) and said particulate photoconductive zinc oxide (II) having sensitivity in the same spectral region, but one of said particulate photoconductive zinc oxides having a sensitivity of from 1% to 8 times that of the other of said particulate photoconductive zinc oxides, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly-distributed insulating binder-material containing particulate photoconductive zinc oxide (11), the number of said small spots being between 10 and 300 per square inch, the said insulating binder-materials of said coatings being of such nature that
  • An electrophotographic element comprising a continuous coating on a paper support of particulate photoconductive zinc oxide (I) having a given sensitivity, dispersed in an insulating binder-material, and coated over said continuous coating a discontinuous coating comprising small spots of substantially, uniformly-distributed insulating binder-material containing particulate photoconductive zinc oxide (II) having a different given sensitivity, said particulate photoconductive zinc oxide (I) and said particulate photoconductive zinc oxide (11) having sensitivity in different spectral regions and one of said particulate photoconductive zinc oxides having a sensitivity lying beyond about 410 me, from 2 to 98% of the surface of said continuous coating being coated with said small spots of substantially, uniformly-distributed insulating binder-material containing particulate photoconductive 12 zinc oxide (11), the number of said small spots being between 10 and 300 per square inch, the said insulating binder-materials of said coatings being of such nature that said coatings have a low decay rate in the dark when said coatings have

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GB12107/58A GB895723A (en) 1957-04-17 1958-04-16 Electrophotographic elements
FR1210685D FR1210685A (fr) 1957-04-17 1958-04-16 Nouveau produit électrophotographique et composition pour sa fabrication

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US3060019A (en) * 1958-07-22 1962-10-23 Rca Corp Color electrophotography
US3170790A (en) * 1959-01-08 1965-02-23 Xerox Corp Red sensitive xerographic plate and process therefor
US3188208A (en) * 1959-05-04 1965-06-08 Xerox Corp Spectral contrast control in xerography
US3252835A (en) * 1960-06-01 1966-05-24 Agfa Ag Sensitization of electrophotographic layers
US3298830A (en) * 1962-06-16 1967-01-17 Agfa Ag Imagewise sensitization of electro-photographic layers
US3310401A (en) * 1963-08-28 1967-03-21 Rca Corp Electrophotographic member and process utilizing polyarylmethane dye intermediates
US3378371A (en) * 1965-04-08 1968-04-16 Eastman Kodak Co Photoconductive material for electrophotography
US3525613A (en) * 1963-08-12 1970-08-25 Rca Corp Thermoplastic deformation imaging process
US6651823B1 (en) * 2000-05-15 2003-11-25 Honeywell International Inc. Plastic filter housing formed from multiple sections and having a skewed weld seam, and filter incorporating same

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GB314838A (en) * 1928-04-03 1929-07-03 Charles Ruzicka Improvements in or relating to light sensitive cells
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US2331444A (en) * 1941-09-16 1943-10-12 Titanium Alloy Mfg Co Photoconductive material and method
US2358060A (en) * 1940-09-03 1944-09-12 Eastman Kodak Co Photographic materials
US2703282A (en) * 1950-12-14 1955-03-01 Eastman Kodak Co Increasing the exposure latitude of photographic emulsions by sensitizing
US2727808A (en) * 1953-10-21 1955-12-20 Rca Corp Panchromatically-sensitive zinc oxide
US2737766A (en) * 1953-12-04 1956-03-13 Garner Paul Disc harrows
US2862815A (en) * 1953-10-01 1958-12-02 Rca Corp Electrophotographic member

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Publication number Priority date Publication date Assignee Title
AU201416A (en) * 1916-09-08 1917-05-29 Belle Fageol Rollie Improvements in trailing road vehicles
GB314838A (en) * 1928-04-03 1929-07-03 Charles Ruzicka Improvements in or relating to light sensitive cells
US2358060A (en) * 1940-09-03 1944-09-12 Eastman Kodak Co Photographic materials
US2318597A (en) * 1941-01-03 1943-05-11 Eastman Kodak Co Photographic printing material
US2331444A (en) * 1941-09-16 1943-10-12 Titanium Alloy Mfg Co Photoconductive material and method
US2703282A (en) * 1950-12-14 1955-03-01 Eastman Kodak Co Increasing the exposure latitude of photographic emulsions by sensitizing
US2862815A (en) * 1953-10-01 1958-12-02 Rca Corp Electrophotographic member
US2727808A (en) * 1953-10-21 1955-12-20 Rca Corp Panchromatically-sensitive zinc oxide
US2737766A (en) * 1953-12-04 1956-03-13 Garner Paul Disc harrows

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060019A (en) * 1958-07-22 1962-10-23 Rca Corp Color electrophotography
US3170790A (en) * 1959-01-08 1965-02-23 Xerox Corp Red sensitive xerographic plate and process therefor
US3188208A (en) * 1959-05-04 1965-06-08 Xerox Corp Spectral contrast control in xerography
US3252835A (en) * 1960-06-01 1966-05-24 Agfa Ag Sensitization of electrophotographic layers
US3298830A (en) * 1962-06-16 1967-01-17 Agfa Ag Imagewise sensitization of electro-photographic layers
US3525613A (en) * 1963-08-12 1970-08-25 Rca Corp Thermoplastic deformation imaging process
US3310401A (en) * 1963-08-28 1967-03-21 Rca Corp Electrophotographic member and process utilizing polyarylmethane dye intermediates
US3378371A (en) * 1965-04-08 1968-04-16 Eastman Kodak Co Photoconductive material for electrophotography
US6651823B1 (en) * 2000-05-15 2003-11-25 Honeywell International Inc. Plastic filter housing formed from multiple sections and having a skewed weld seam, and filter incorporating same

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GB895723A (en) 1962-05-09
FR1210685A (fr) 1960-03-10

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