DE1608200A1 - Photosensitive plate - Google Patents

Description

Patent attorneys Dipl.-Ing. RWeickmann, Dr. Ing.A.Weickmann

DiPi _n -ING. EWeickmann, Pipl.-Phy $. Dr. K. Fincke Dipl.-Ing. R A.Weickmann, Dipl.-Chem. B. Huber

SB

RANK XEROX LIMITED
Rank Xerox Eouse ■
338, Euston Road
London, HW 1
England

8 MUNICH 27, DEN

MÖHLSTRASSE 22, CALL NUMBER 483921/22

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The invention relates "to the xerographic technique, and more particularly to a photosensitive plate. ■

In the xerographic technique, as is known, a plate is used to generate an electrostatic latent image, which plate consists of a conductive substrate, for example made of metal, and a photoconductive insulating material layer applied to it. A plate suitable for this purpose consists of a metal base and a layer of vitreous selenium. Such a plate is characterized by its ability to absorb electrostatic charges as well as its selective dissipation during exposure, whereby it is mainly sensitive to light in the blue-green spectral range.

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Vitreous selenium is the standard material in most cases for commercial pcerographic technology, but can- \ Many of its properties can be improved by adding alloying elements, for example the sensitivity spectrum, photosensitivity, thermal stability, etc. The advantages of modifying vitreous selenium by adding appropriate amounts of arsenic and the larger area obtained with it of the sensitivity spectrum go from the US patent specification 2,803 5 ^ 2 and 2,822 JOO. This results in an increase the overall photographic speed as well as an improvement in the stability of the photoconductive layer.

Although vitreous selenium has a satisfactory sensitivity photoconductors are required for fast-running processes, which have an increased sensitivity and a wider range of sensitivity compared to vitreous selenium. This requires plates that are designed for rapid imaging or the small time factor a very high sensitivity . -

"ability or panchromatic properties.

The addition of antimony represents a step in this direction in suitable amounts for selenium, as described in German patent application R 4-6 503 IXa / 57e. Glass-shaped alloys of antimony and selenium result in a photosensitive composition having a sensitivity factor of up to 12 times larger than that of glasfö & gem selenium, the relative sensitivity to that of vitreous Selenium is up to 3 times larger in the blue-green spectral range. t Although with this alloy the xerographic speed

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1808200

has been increased, however, there is still a disadvantage ^ that in a relative lack of thermal stability in terms of aif Crystallization exists. .

To avoid this drawback, the invention provides a photosensitive plate having a photoconductive Isolierstoff- _r ~ layer of a glassy alloy of arsenic, antimony and selenium has. . ; ^ ^:

These alloys are formed in a manner similar to the vitreous, photo-conductive alloys of the arsenic-selenium system, which are described in US Pat. It has been found that a glass £ örmige alloy of arsenic, antimony and selenium 'in a range of up to about 50 ^ At (4 to 8.7 wt. #) Arsenic, about 0.1 to 22 ktfo (0.15 to 3 ¹ IjO wt g is greater than that of glasfcriniiqem selenium, wherein the thermal stability is improved and become larger set as diejenise.des vitreous selenium ICANN. A preferred range of up to about 4-5 At ¹ P (4-5.7 wt.; 5) arsenic, up to about 13 It ^ (18.8 wt At about 55; i- (56.3 wt>. 6) results in the selenium Lombination optimum stability and light thermischei- ¹ 'empfindlicälceit. The lor maximum thermal stability erforderliehe .Verhältnis "-from arsenic to antimony is intended; on the order of about 2 to 4 * At $ arsenic or antimony hÖh0r per -1At ^ lie in $ eäem -% | ^{#; e."} Is this: ^ A.rsen in an amount of at least approx. ■

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0.5 At # '"(O» "6 GeWi ^) exist to be an acceptable thermal Maintain stability while eating an amount of antimony at least approx; 0.1 At # (0.15 wt. ^) Should be present to the desired sensitivity or sensitivity distribution obtain. *

The benefit of these improved photosensitive fabrics together- ■ 'Setting is based on the following description of the invention.'Hand fc of the characters Ifervor

. Fig. 1 shows part of the ternary diagram for antimony, 3 S and selenium,. ^; ■ ':, · ■

Figure 2 shows a number of spectral sensitivity curves for? _Λ a group of photoconductors in the form of a '• ternary alloy according to the invention. - ■ "..;:; · .. - ■;

• The ternary diagram shown in Fig.1 shows the surface parts, for which the alloy antimony-arsenic-selenium has the desired photoconductivity properties and has thermal stability. The area below the curve A-B-G-D represents compositions of matter; represent, which preferably have thermal stability. The area under the curve E-F-G-H, which is also the area under the Including curve A-B-G-D, contains additional compounds with somewhat lower thermal stability, but with somewhat better xerographic properties than those under the Curve A-B-G-D. . . '

The dashed "lines-J-" uiid-K- are the limits for the minimum Amounts of arsenic and antimony for the preferably ternary alloy.

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As can be seen from the ternary diagram, the arsenic is said to be in a Amount of at least about 0.5 at # (0.6 wt., $) And the antimony in in an amount of at least about 0.1 At $ (0.15 wt, $).

The inventive vitreous alloys of arsenic, antimony and selenium can be produced by any suitable process. Typical processes of this type are conventional single-source evaporation and flash evaporation Selenide compounds result, the vapor pressures of which are better than those of the elementary substances. The initial alloys are made by weighing the elemental arsenic, antimony and selenium and entering in _; a vacuum is created inside a silica glass ampoule. The fabrics are heated to 600 G for a few hours and then cooled to room temperature in the air. Depending on the composition, the cooled alloy is completely polycrystalline, a mixture of crystalline and amorphous phases or completely amorphous. The pre-reacted alloy is then converted into a> | Ball mill ground to a small particle size of less than about 1 mm in diameter.

In the case of single source evaporation, an appropriate amount of the pre-reacted alloy in a heated flat crucible or a boat entered, which is in a vacuum of for example 10 to 10 mm of mercury column.

The crucibles can be made of any neutral material such as quartz, Molybdenum, or ceramic-lined metal, »The Le-

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alloy of arsenic, antimony and selenium is at a temperature _; held, which ensures the ore ring for a deposition of sufficient vapors within a reasonable time. This temperature is normally higher than the melting point of the alloy. A total evaporation time of approx. 20 minutes at approx. 400 ° G and the vacuum described above results in the formation of an alloy layer with a thickness of approx. 20 to 40 microns.

fe A pad is placed over the heated crucible, on the leg; eration is evaporated. This document is based on kept at a relatively low temperature. Suitable. Temperatures lie between approx. 60- and 150 ° C. .- ■. ·.: -: * -..-

Another method of vaporization is relaxation vex vaporization. At a vacuum similar to that mentioned for the single-source evaporation, the pre-reacted alloy of arsenic, antimony and selenium with a particle size of less than Λ mm in diameter is selectively dripped into a heated, neutral crucible, which is at a temperature of approx. 450 to 660 C. is held. The vapors generated by heating the mixture are evaporated onto a base placed above the crucible. The alloy is dripped in at a rate sufficient to prevent the formation of an alloy melt in the crucible, which minimizes the problem of fractional evaporation. The substrate is at a temperature of approx. 60 to 150 ° G. This process is continued until the required thickness of the vitreous alloy layer is present on the substrate. BADORiMAt. ■

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pi 'The alloys according to the invention can be used on any substrate

?; be applied in a conductive or insulating manner * Serve for this Metal plates made of brass, aluminum, gold, platinum, for example,

; Steel, etc. The base can be of any suitable thickness, rigid or be flexible, have the shape of a sheet, a band, a cylinder or similar and are covered with a thin layer of plastic.

. be pulled. Further, they may be made of metallized paper, plastic, · with a thin coating of aluminum or copper iodide-provided plastic, with a thin layer of partially transparent λ copper iodide, tin oxide or gold consist LABEL FOR glass. In certain cases it is even possible to dispense with the support after the alloy has been formed.

The "thickness of the alloy layer made of arsenic, antimony and selenium is not critical. It can be approx. 0.1 micron or JOO micron or more, for most applications it is but between approx. 20 and 80 microns * · ·

In another embodiment, the inventive photo, conductive alloy doped with a halogen such as iodine, chlorine or bromine in order to reduce the residual voltage and reduce the electrical To improve properties in general. The halogen doping agent is present in amounts of approximately 10 "" * wt. # up to 2 wt. {£.

In a further embodiment of the. Invention, the alloy of arsenic, antimony and selenium in a layered 'Configuration' -... .Werden used "Typical arrangements consist of a relatively thin SAE% eirtAvanvca- -SSI * ^ ^ pis microns arsenic-antimony Selenlegie- \,. , tion over a reiktiv./thicker layer -from '^ iMf orm-ig'eia selenium.

_ ₈ _ 1606200

Another typical structure includes an alloy of arsenic and selenium, for example, disclosed in US Pat. No. 2,822,300 which is used in place of the selenium in the above-mentioned two-layer configuration. It should be noted that both layers a two-layer structure can be doped with a suitable halogen in order to improve the electrical properties » Structures with more than two photoconductive layers are also encompassed by the present invention. The alloy layer of arsenic, antimony and selenium can also be used on the The substrate boundary layer of a transparent substrate can be formed and exposed through this substrate. In this embodiment, the alloy of arsenic, antimony and Selenium alone or in combination with other photoconductive layers of the type mentioned above can be used.

Description of preferred exemplary embodiments

The following examples serve for further specific explanation of the present invention in terms of a method of making a photosensitive plate having a. Arsenic-antimony-selenium alloy. The percentage values relate to the weight, unless otherwise stated. Provide the examples Various preferred embodiments for the production of an external arsenic, antimony and selenium consisting of photoconductor.

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Example I.

. An initial alloy is from 18 wt ^ Ar sen, -. 1% by weight antimony and 81 wt · ^ selenium in elemental form prepared and maintained within a Silikaglasampulle under vacuum closure.... The mixture is then heated for about 2 hours to about 600 ° G in a rocking oven and then cooled to room temperature. The alloy obtained is a solidified polycrystalline matrix. , mixed phases, which are then ground in a ball mill to a particle size of less than about 1 mm diameter. . (J

Example II

One. 40 "micron alloy layer of vitreous arsenic, antimony and selenium is formed on an aluminum substrate of about 1 Geitf # antimony, 18 wt # arsenic and 81 wt% selenium as follows:... The prereacted alloy of Example I is converted to a ceramic Lined flat metal boat measuring 5 x 10 cm. The particulate alloy is evenly distributed over the surface of the boat. The boat is then placed in a vacuum chamber. A 10 χ 12.5 cm aluminum plate is carefully cleaned and placed in the vacuum chamber 50 cm above the boat and kept at a temperature of about 65 ° C., for which purpose a water-cooled plate is used, the chamber is brought to a vacuum of about 10 mm of mercury long evaporated onto the aluminum plate by about 20 minutes heating the boat to 400 ° 0th Then, the boat is cooled to room temperature, the V removed and the aluminum plate coated with the arsenic-antimony-selenium alloy was removed from the vacuum chamber.

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Due to the fractionation during evaporation, the outer surface of the alloy layer formed in Example II

Antimony deten plate a greater percentage / than the interior the alloy layer, with the outer surface of the alloy layer containing the lowest amount of antimony. This was done through Analysis determined by electron probe.

Example III

The plate made by the procedure given in Example II is made in a xerographic process as follows exposed: The plate is placed on a corona device positive voltage of approx. 500 volts and then charged with a tungsten filament lamp of 100 watts from a distance of approx. 4-0 cm exposed for about 1/2 second to form an electrostatic latent image on its surface. The latent image then becomes developed by cascading electroscopic drawing particles across the imaged surface. That; Image is on Transferred to a sheet of paper and made "permanent" by heat-setting. In this way, excellent reproduction results of an original image. - ·

Example IV " j

A 25 micron thick layer of a vitreous arsenic-antimony-selenium alloy is formed on an aluminum backing as follows: A pre-reacted alloy of approximately 12 wt.% Antimony, 28 wt. % Arsenic and 60 wt manufactured. The pre-reacted alloy is placed in a brass funnel which contains a copper chute _λ through which the particles are placed in a quartz crucible.

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halfway through the funnel. The quartz crucible is surrounded by a resistance heater that has a temperature voti approx. 600 ° C. An aluminum pad is placed on top of a water-cooled plate placed at a temperature of approx. 70 ° G is held * The aluminum washers and the plate are at a distance of approx * 50 cm above the quartz crucible arranged. A bell is placed over the entire arrangement, which evacuated to a negative pressure of approx. 10 ~ mm of mercury becomes j and the quartz crucible is raised to a temperature of approx. 600 ° O heated. When this temperature is reached, the under ■ des? Stoked open the intended flap of the funnel and one small sample of the arsenic-ah-timon-selenium alloy in the quartz crucible entered. The oil mixture evaporates quickly, and the vapors of arsenic, antimony and selenium come into contact with the aluminite underlay. This procedure is approx Continued for hours, after which a 25 micron thick layer a glass-shaped antimony-arsenic-selenium alloy of approx. 12 Wt. # Antimony, 28 wt.> Arsenic and 60 wt. ^ Selenium on the aluminum base is available. The "crucible is then on room | cooled down, the vacuum unleashed the coated under- ' removed from the chamber.

- Example V

The alloy formed in Example IV is then used in the game III described way exposed. It turns out to be an excellent one Copy of an original picture *

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- Examples VI - IX

A group of four plates is prepared for comparison of the sensitivity spectrum. All four plates contain a 40 micron thick layer of photoconductor on an aluminum backing. The plate Kr.1 contains a 40 micron thick layer of vitreous selenium which is manufactured in accordance with US Pat. No. 2,970,906. The plate ITr.2 contains a 40 micron thick layer of a vitreous alloy of 18 wt. # Arsenic and 82 wt. # Selenium doped with approx. 0.1 % iodine, which is obtained by the "patent application R 44 804 IXa / 57e described method is manufactured * the plate # 3 contains a glassy alloy of 14 wt.% antimony, and 86 wt. ^ selenium prepared by the in patent application e contains 46,503 Ixa / 5? e methods described. the plate Hr * 4 as described in example I ternary alloy of about 1 wt.% antimony, 18 wt. $ arsenic and 81 wt. # selenium doped with about 0.1% iodine. the Kurven.des sensitivity spectrum for each of the four plates was added and xverden have the course shown in Figure 2.

In Fig. 2, the sensitivity of the four plates is shown at different

ρ are represented by wavelengths. E represents the energy in ergs / cm that is required to discharge the plate by approx. 25%. The plates were each tested at different wavelengths by bringing each plate to an initial voltage of about 15 volts per micron and then at the respective wavelength

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approx. 2 x "10 photons per cm lake was illuminated. As shown in the curves is shown shows the arsenic-antimony-selenium elimination according to the invention at 4000 Angstroms about twice the sensitivity than the plate with the '"el as form ine η selenium layer and the plate

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with the arsenic-selenium alloy. Also is its sensitivity much larger than that of the "binary antimony-selenium alloy.

As can be seen from the foregoing, the arsenic-antimony-selenium alloys produced according to the invention have an up to approx. 7000 Angstrom: increased sensitivity spectrum and improved sensitivity in the shorter wavelength range. Additionally, these alloys have better thermal stability than those with antimony-selenium photoconductors. is not achievable, λ where the thermal stability at certain ratios of arsenic to antimony exceeds that of vitreous selenium.

Although specific ingredients and amounts of substance in the above Description of preferred exemplary embodiments of the invention given other substances and process steps can also be used, how they continue for example; are on top, -with similar ones Results are used. "In addition, other substances be provided that a synergetic, improving or otherwise modifying effect on the properties of the erfindungsgeraässer Show optical disks.

After knowing the description, other embodiments are available to the laughing man and further developments of the invention are possible. These will encompassed as a whole by the basic concept of the invention.

Claims (1)

Λ / Photosensitive plate with a photoconductive insulating material layer, characterized in that the photoconductive insulating material layer consists of a vitreous alloy of arsenic, antimony and selenium. 2. The photosensitive plate of claim 1, characterized in \ that the arsenic is present in an amount of at least about 0.5 atomic percent and the antimony is present in an amount of at least about 0.1 atomic percent of the photoconductive insulation layer " 3. Photosensitive plate according to claim 2, characterized in that the alloy contains at most 50 atomic percent of arsenic unä Höetistens 22 atomic percent of antimony, the remainder of which consists of _; % Selenium consists. ^: , ■ / \, '''; * % 4. Photosensitive plate according to one of claims 1 to 3 'thereby'; characterized in that the alloy is moirized with a halogen; ß _: 5. Photosensitive plate according to one of the preceding claims,> characterized in that the photoconductive insulating material layer is applied to a supporting base » 6. Photosensitive plate according to claim 5 »characterized in that that the pad is electrically conductive. .. ■■■ "- 15 -; 103800/0413 * "7» photosensitive plate according to claim 5 or 6, characterized in that between the supporting base and the photoconductive Insulating material layer at least one photoconductive intermediate layer-provided is. 8. Photosensitive plate according to claim 7> characterized in that the photoleii; capable intermediate layer consists of vitreous selenium * -: "-".-.- .'-..-. - -; -. '. ■ - ■ "...." .--- 9. Lichteifipfindliche platform according to claim 7 »characterized, ™ that the photoconductive intermediate circuit. from an arsenic-selenium ■ Government exists. - ", Λ / ΐ- ./V ^: ■ 10. Photosensitive plate according to one of claims 7 to 9, characterized characterized in that the photoconductive intermediate layer with a Halogen is doped. '. ^. 11. Photosensitive plate according to one of claims 7 to 10, characterized in that several · ¹ photoconductive intermediate layers are present are seen. 12. Photosensitive plate according to one of claims 5 to 1-1, characterized in that the supporting base is transparent. 13. Photosensitive plate according to one of claims 5 to 12, characterized characterized that the arsenic-antimony-selenium layer with a white. teren layer of a photoconductive substance is coated. . ;. ■ ■ "■ -... ■ -" ■ - 16 - T0f8O9704ia 14. Photosensitive plate according to one of claims 5 to 12, characterized in that the arsenic-antimony-selenium layer is coated with several photoconductive layers. 15. A method for producing a according to any one of claims 1 ■ to 14 formed photosensitive plate, characterized in that a mixture of arsenic, antimony and selenium on a supporting base which, with regard to its temperature, enables the condensation of these components in a vacuum is vapor deposited, whereby a vitreous arsenic-antimony-selenium alloy is formed on the supporting base; forms. 16. The method according to claim 15, characterized in that a electrically conductive support is used. 17. The method according to claim 15 or T6, characterized in that that the mixture of arsenic, selenium and antimony was dropped into a heated crucible and "fung is applied to the supporting base. 1c. Method according to Claim 16 or I7, characterized in that that the arsenic, the antimony and the selenium are evaporated from a low, flat boat. 19. Thermally stable, vitreous photoconductive alloy of Arsenic, antimony and selenium, produced by the method according to one of claims 15 to 18, characterized in duiOli distribution determined by the curve ■ -A-B-G-I) in jIh.I and by sur.in.de-S! i approx. 0.5 atomic percent arsenic and 0.1 atomic percent. ^ rorsenr ^{AR r 'ino -:} * 10 9809/0418 ⁸ ^ D original - 17 - " -M- 20. Glass-shaped photoconductive alloy of arsenic, antimony and selenium, produced by the method according to one of claims 15 to 18, characterized by a distribution ¹ determined by the curve Ej? -GH in Fig.i and by at least about 0.5 Atomic * percent arsenic and 0.1 atomic percent antimony. 21. An imaging method for using a according to one of the claims 1 to 14 formed photosensitive plate, characterized in that the plate is uniformly electrostatic charged to form a latent electrostatic Image with an activating radiation distributed according to a standard ■ is exposed and developed to make this image visible. 0Rf <3iN _AL $ 10980/0411 «2. Blank page