DE1483294B2 - Use of a substance as a photoconductive material - Google Patents

Description

3 4

Appealing photoconductive material, previously used, which has a low content of crystallites

beat. or nuclei that are uniform in the

All quantities are given in percent by weight. Layer are distributed, have.

Such a material can be used in a very even manner. In addition, other elements or components can be added to the photoconductive mixtures with moderate, thin films as photoconductive layer 5. A particular advantage of this photo-joining, the specific effects on the conductive material, is that a spectral sensitivity or a photoconductive layer produced from it cause a particularly tendency to crystallize,
high sensitivity to shorter-wave radiation.For numerous purposes, if visible light is present, it is worth seeing, if this photo- ίο, to apply the mixture beforehand as a coating on a subconducting layer by means of a positive charge, whereby the mechanical stabilization has been sensitized while the same layer was doing , the contact with a voltage source or the like can be significantly improved compared to exposure to visible light. So that is practically insensitive. With such a pre-mix z. B. when used for photoconductive layer treated photoconductive layer for electrostatic dry printing as a coating pierplatten are thus particularly suitable for on a base of conductive material, as it is used in recordings or images, the aluminum, magnesium, brass, steel or Chromium, generated with electromagnetic radiation or made of non-conductive material such as glass or paper, which is shorter-wave than visible light. Plastic or the like, as far as this with a coating

A particularly "quickly tiring" copy plate 20 made of conductive material such as gold, tin oxide, copper results if this is provided with a photoconductive iodide or the like, be opened. From the above-mentioned photoconductive material, a layer of conductive material emerges Material is made and the photoconductive material is not just mechanical stability Layer before exposure with a negative on the copying plate produced is significantly enlarged, charge is sensitized. Such a plate is more suitable for its presence is particularly suitable for reproductions using a directly below the surface of the Generation of electromagnetic radiation in the electrically grounded surface lying in the layer area. Charging by means of a corona discharge is essential

The photoconductive material is lent facilitated by mixing.

made of thallium with amorphous selenium. It should also be mentioned that for this purpose at the same time, up to about 5% of the "conductive material" is not necessarily included in the preparation of the mixture Thallium can be used, must be considered, a metallic conductor must be, rather it is sufficient that selenium in amorphous form compared to thallium when the electrical resistance is extremely sensitive by a few tens and that thallium potencies is lower than the resistance of the Belich additives down to 0.0001% noticeable effects in 35 th photoconductors. There is therefore the possibility of reference point to the properties of the alloy. some special glasses and art ais as a base An additive has become a particularly favorable area, even without a metallic coating about 0.0005% to about 0.002%, especially since turning. On the other hand, they become certain other larger ones Additions often contaminate themselves with charging methods applied, such as. B. the in bring, without additional beneficial effects to 40 of the United States patent 2,922,883 described time, drive a bilateral corona charge, so can

The thallium can practically neglect the selenium according to any of the conductivity of the substrate.

known method can be added. So be casual, so that the choice of material

For example, the selenium can be adjusted to a temperature for the substrate only after its mechanical

heated above its melting point, where 45 properties are aimed.

after then the melted selenium, the To apply the mixture to the surface

required amount of thallium is added. practically all known

Mixing is expediently carried out under drive in which the amorphous state of the mixture

Stir in order not to destroy an intimate mixing of the two, d. that is, that he was practically frozen

Components to achieve. At this point it must be 50 without any noticeable crystallization

it should be mentioned that it is not certain whether this is the wrong material. These procedures include

added thallium with the present in excess, for example evaporation in a vacuum on a

which selenium with the formation of a small amount of cooled base, as well as pouring, dipping or

Thallium selenide undergoes a reaction or whether a similar process.

solid solution of the two components is created. 55 Evaporation in a vacuum has therefore proven to be a particularly advantageous process, especially since "mixture" is to be understood in its broadest sense. the surfaces thus obtained are extraordinary. Accordingly, both those materials will be smooth and uniform. The thickness of the substances to be produced, which contain a small proportion of thallium selenide, in loin layers, depends on the particular dissolved form, as well as those which are made up of the intended use of the finished panels. For example, the two original components selenium and thal- lium are required for some areas of application without the addition of a small amount of reaction- thin coatings, the layer thickness of which exists in the product. However, the former is on the order of a few microns. For possibility, that is, the formation of a bond, which is more likely to be used in the general electromechanical. The mixture is deposited in amorphous 65 static dry print copying processes are da-form. This is very similar to the amorphous mode against layer thicknesses of around 40 μΐη to around 100 μία fication of selenium. The designation appropriate. In the X-ray area or when using the »amorphous form«, layers of other very high-energy radiation are also required here.

Significantly greater layer thicknesses are required, for example on the order of about 250 μm up to about 500 μΐη to the braking effect of the larger Use layer thickness.

A particular advantage of the photoconductive material mentioned is that when the material is used for the production of copy plates for the electrostatic dry printing process, these copy plates show noticeably different properties depending on the polarity of the charge. Is z. If, for example, a plate made using this material is positively charged, it is practically insensitive in the visible range, while extremely high sensitivity is retained ^{in the X-ray range (at wavelengths of about 10 ~ 6} to 10 ^{~ 9 cm)} If such a plate is provided with a negative charge, it is very sensitive in the visible region of the electromagnetic spectrum (at wavelengths of about 4000 to 7000 Angstroms) and also shows an extremely strong remanence of the fatigue effect after the first exposure After the initial exposure, a charge pattern remains only in the originally unexposed areas by duplicating n of the original without having to re-expose the photoconductive material each time it goes through the duplication process.

In the following, the invention is to be explained using further exemplary embodiments.

Example I.

99 parts by weight of high-purity selenium (degree of purity 99.99% and more) and 1 part by weight of thallium (in elemental form) are initially, for. B. premixed by heating them together in a nitrogen atmosphere. This premix is placed in a boat made of inert material, e.g. B. Pyrex glass, placed in an evacuable evaporation vessel and arranged there below an aluminum plate coated with a thin oxide film. Then the evaporation vessel is closed and ^{evacuated until a vacuum of about 10 ~ 5} mm Hg is reached; the aluminum plate is kept at a temperature of about 50 to 60 ° C. The selenium-thallium mixture is then evaporated by heating the Pyrex boat to a temperature of about 280 ° C. and condenses on the surface of the aluminum plate to form a uniform coating. Although thallium has a melting point of about 300 ° C, it dissolves in the selenium, which melts at about 215 ° C, to form a solid solution and is then evaporated together with the selenium. In this way, a very uniform, glossy coating of amorphous material is obtained, the layer thickness of which is about 160 μτα . After the evaporation process has ended, the evaporation vessel is cooled while maintaining the negative pressure. Then the jar is opened and the plate is removed. The plate produced in this way is then provided with a positive charge by means of a corona discharge. The subsequent examination of the plate with the aid of an electrometer shows that the initial charge on the plate is about 760 volts.

A second check after the panel has been exposed to daylight for three minutes resulted in a charge in excess of 700VoIt. Another exposure of the same

ίο plate with a conventional light source whose Radiation range lies in the visible range of the electromagnetic spectrum, leaves behind in the exposed Areas also have practically all of the original charge (the remaining charge is about 675 volts). Attempts to develop the plate exposed in this way proved unsuccessful. The same plate is then cleaned and charged again (initial potential again 760 volts). Then the plate with

ao X-rays exposed. For example the figure ^ to make a large bovine bone. The resulting latent electrostatic image is then converted into a visible image by means of a cascade development. One receives on this way a high quality visible image of the bovine bone. The developer mix used contained finely divided toner particles and coated, spherical carrier particles. After completion of the development process, the developed image is then printed on a copy paper transferred and fixed there by heating.

Example II

The plate described in Example I above is made in the same manner as in the previous one Example provided with a charge by means of a corona discharge. The only difference is that the polarity of the charge is opposite to that in Example I; H., the plate is given a negative charge. The initial charge on the plate is as the measurement with the help of an electrometer shows, 675 volts. The plate is then in contact with one Original exposed to a light source and developed in the manner explained on the basis of the 1st example. After transferring the developed image to copy paper, the plate is recharged and checked by means of an electrometer. Although the plate was not exposed in the first exposure Areas practically maintaining the entire charge takes place in the previously exposed areas a discharge of nearly 98 per cent took place. The plate is then developed without additional exposure, the developed image is then transferred to copy paper and fixed there. Man thus receives a high-quality image of the first original. Even with about ten repetitions this operation did not detect any noticeable deterioration in the image quality of the copies will.

Examples III to VII

According to the method described in Example I, further copy plates were produced which differed from the first plate by a different thallium content. The thallium content in the third example was 0.5%; in the fourth example 0.1%; in the fifth example 0.05%;

in the sixth example 0.01% and in the seventh example 0.0001 ° / o.

Each of the panels was tested in the manner illustrated in Examples I and II. Essentially the same results were achieved, apart from a gradual decrease - corresponding to the thallium content contained in the mixture - of the stored charge after exposure to visible light for about three minutes. This decrease is extremely insignificant, however, since the plate according to Example VII with a thallium content of 0.0001% still shows a charge of 500VoIt after this exposure and since its sensitivity ¹ in the X-ray range is just as great as that of the plate with a thallium content of 1.0%.

Example VIII

To make sure that any other impurities that may be present have no effect on the plate properties tested, was one with a coating of pure amorphous selenium provided copier plate (the selenium was the same as in Examples I to VI) in the hand of the

ίο Examples I and II examined manner explained. It it was found that this plate was practical after three minutes of exposure showed no stored charge and, moreover, none based on previous exposures "Fatigue pattern" could be determined when the plate was examined according to Example II.

409 512/98

Claims (2)

1 2 bring and stay there, whereby the process of the patent claims: "image transfer" is completely ignored in this process. 1. Use of a substance consisting of Although high quality, under use-0.0001 to 5%, preferably 0.0001 to 0.002%, 5 manure photoconductive materials, such as. B. from Thallium and the remainder of amorphous selenium, as copier plates produced on elec- amorphous selenium in the tromagnetic radiation, which is in the area of the basic process of the previously explained visible light or is shorter-wave than electrostatic dry pressure thanks to what you can see Light, more appealing photoconductive adhesive properties with good success applied material. io det, they are for other imaging methods 2. Use of a substance that is unusable due to these properties. Setting according to claim 1 for the purpose of So are z. B. Plates made using Claim 1 with the proviso that the material was made of amorphous selenium, due to as a photoconductive layer on the active plat- its sensitivity both in the visible range th in the electrostatic dry printing as well as in the X-ray range of the electromagnetic is set. Spectrum, to be handled with extreme caution and must, insofar as they are to be used in the X-ray area, before the effect of the Protected from daylight. 20 In addition, this material is due to the fact that using amorphous '-''Selenium made ⁷ - copy plates one after the other in rapid succession of repeated times under the conventional electrostatic dry printing process. The present invention relates to which may be used without the foregoing of a substance as a photoconductive material. the exposures have any effect on the photoin Recently there has been increased interest in the conductivity-isolation response of selenium for photoconductive alloys, which are used for special purposes in the following processes, for areas of application suitable, developed. This multiplication process is unsuitable. These multipliers Interest was mainly due to the surveillance procedures based on the hold dispatch Subsequent questions about TV tubes, like the one caused by the exposure Office copiers and similar devices, for charge image in the photoconductive layer during such alloys are used, the subsequent reproduction processes. Such evoked. Photoconductors, which one has as "very tiring" Photo-So z. B. can denote the application of electrostatic conductors 35 need only exposed once Dry copying for the past couple of years has become too late for repeated traversal of the experience an extraordinarily large increase. The reproductive process involved a multitude of duplicates known dry copying process is known to yield data on the first image produced. Of the in that a photoconductive insulating layer, includes reproduction process also in this case The essential part of an electrostatic 40 includes the following operations: Creating an equal-dry copy plate is, superficially with a moderate surface charge, developing the latent image resulting from the exposure provided with uniform electrostatic charging and and is thereby sensitized. Then this is done transferring the developed image to a copier plate corresponding to an image activating elec- trical paper or a corresponding pad. Since it is tromagnetic radiation, such as light, X-ray 45 in a material that adapts to the initial lung or the like, exposed. As a result, the on-exposure is "remembered" to avoid a quickly tiring painting acts selectively in the exposed areas, it retains it in the initially exposed areas builds, while it has a relatively high conductivity in the unexposed photo areas, so that the conductive insulating layer is retained. On this renewed application of an even charge In this way, there is only one formation 50 in the photolayer during each replication process electrostatic latent image. The latent provided a recharge to the background areas The image can then be developed or made visible to the exclusion of the originally exposed values. by making finely divided electroscopic rich, in which a rapid charge depletion after Marking material on the surface of the photo- the charging takes place, causes. applying conductive layer. There the fine 55 Mixtures of thallium and selenium were per se distributed material due to its charge already from the literature reference M. H a η s e η, »Consti- speaking of the latent image. In the tution of Binary Alloys, 1958, pp. 1190 and 1191, Cases where the photoconductive material is known. Can be recycled, the object of the present invention is to- through the finely divided or powdered marking grounds, one for the interests of the electrostatic material formed visible image on a second dry printing process more suitable photo- Surface, e.g. B. a sheet of paper, transfer and indicate conductive material, forms a permanent visible reproduction there. of the original. would be the use of a substance consisting of In other cases where cheaper, only once 65 0.0001 to 5%, preferably 0.0001 to 0.002% Usable photoconductive material for applying thallium and the remainder amorphous selenium as on electro- When this happens, the toner particles react directly to magnetic radiation that is in the visible range the surface of the photoconductive layer is exposed to light or has a shorter wavelength than visible light,