SU449516A3 - Photosensitive material - Google Patents

Description

one

This invention relates to a photosensitive material intended for electrical photographs and.

A photosensitive material for electrophotography is known, comprising a high-insulating transparent layer with a permanently internal polarization and an electrically conductive layer, connected as one piece.

In order to increase the efficiency of latent image formation and to provide high resolution, the thickness of the photosensitive layer is usually increased.

However, at a high cycle speed, fatigue, or hysteresis, is caused by the appearance of a residual charge, which causes a decrease in the photosensitive material’s ability to form a latent image.

The purpose of the invention, the elimination of the effect of residual charge, is achieved by the fact that between the photosensitive and electrically conductive layers there is a layer with low resistivity, the composition of which is close to the composition of photosensitivity J

body layer from the side of the electrically conductive layer.

Usually a pure metal layer is introduced between the low resistivity layer and the electrically conductive layer, or a second insulating layer is placed.

In addition, a pure metal layer and a second insulating layer can be placed between the photosensitive and electrically conductive layers.

Figure 1a-b depicts the distribution of charges in a photosensitive material containing a photosensitive layer with constant internal polarization; Fig. 2 illustrates the photosensitive and electrically conductive layers in ohmic contact; in fig. 3 and FIG. 4 - the proposed photosensitive material; in fig. 5 is a diagram of an apparatus for vacuum deposition of vapors from a gif to inspecting a photosensitive material.

The photosensitive layer contains a transparent, high insulating layer 1, a photosensitive layer 2, and an electrically conducting layer 3, which are integral. ,

The photosensitive layer contains a ZeTv photoconductor that has p-type conductivity and many levels of charge capture. FIG. l and shows the distribution of charges after equal to | 14nogo charge of the surface apo 1 negative

the charge that causes the migration of charge carriers and thereby creates intra polarization. Since the photoconductor has p-type conductivity, carriers of positive charges in a free state under the action of a negative charge deposited on an insulating layer migrate through the photosensitive layer and are trapped at the interface between the photosensitive and insulating layers. The plus sign denotes delayed charges. At the second stage, a positive charge is applied to the surface of the insulating layer 1 simultaneously with the exposure of the image to the layer 2

through the insulation layer. The left and right half of FIG. 16 shows the areas corresponding to the light and dark areas of the exposed image, respectively. In the light areas, under the influence of a positive charge, again deposited on the insulating layer, the carriers of positive charges migrate through the photo-C1S-intermittent layer and create a charge distribution, shown in the left half of FIG. 16. In the dark areas, the charge, the delay at the interface, is unchanged, since there is no charge migration in the sensitive layer. In the second stage of the process, the charge is deposited in such a way that the surface potential of the insulation layer CTiMi is uniform. Application of the polarization (of the charge on the insulation layer O1r111111 dark areas and thereby creates a distribution of the charge / 1ov, shown on the right half

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phi 16, in which the positive charge density differs from the charge density in the light areas shown by 1 in the left half of fig. 16. A delayed charge (plus) is re-energized when the latent image is uniformly irradiated with light, such as light from a light bulb or fluorescent light, to form new free charge carriers. Thus, the charge distribution in the areas corresponding to the dark areas of the image is changed, as shown in Figure 1c.

According to the distribution of the charges shown in 4) ig-1b, the latent image formed in the second stage has different densities of positive charge in different areas, in particular. exposed image, and can be displayed in any suitable way. The resulting powder image can be transferred to a recording material, such as paper. The photosensitive material is returned to its original state for the next cycle of operation, erasing the remaining latent image and removing the wealth of the reader.

Until the photosensitive and electrically conductive layers are in two, side contact, charge carriers migrating in the direction of the electrically conductive layer during the second and subsequent stages are delayed in areas of the photosensitive layer adjacent to the electrically conductive layer (Fig. 2) and can not be released due to C41 absorption of light by the photosensitive material used, creating less than the residual charge that Buabieae-j-rncTejieanc and not completely allow him to separate the charges in subsequent cycles of operation. 3i | 4) eKT hysteresis accumulator-1c in accordance with the number of cycles, thereby limiting the service life of the photosensitive material.

Where the photosensitive and the electrical conductor and the first layers are located in the second insulating layer, the effect of hister & ng is especially significant due to the blocking of charges by the second insulating layer.

When using the proposed photosensitive material (fig.Z) between the layer 4 with low specific resistance and the layer 3 will not be a discrete interface. In the modified photosensitive material (FIG. 4), the second insulating layer 5 is located between layer 4 and layer 3. In the known photosensitive material in which layer 2 is rigidly connected to layer 3, it is difficult to: create two-sided ohmic contact between them. Therefore, a charge blocking phenomenon occurs at the interface, causing an unintended hysteresis.

The use of layer 4 with low specific resistivity, which does not detain or almost does not detain charge carriers, for example, a layer of an alloy of $ eTb with a large content of Te, not disturbing the migration of charge carriers in this layer. Charge carriers that migrate in the direction of an electrically conductive layer easily reach a layer with a low resistivity and accumulate in it in the form of free charges. Thus, the possibility of creating a hysteresis is eliminated, which makes it possible to reuse the proposed photosensitive material at a high cycle rate. The electrically conductive layer is made of metal or of any material having a relatively low resistance, such as thin metal foil, electrically conductive paper, and electrically conductive glass. Different materials can be used to make the photosensitive layer and the low resistivity layer. For example, blends with different content of §6 and Te can be used to make a photosensitive layer of CTVV. For this, a pair of pure Te or a mixture of Te and Sec, containing a small amount of 3®, is deposited on the surface of the electrically conductive layer, a layer of Te and 5e alloys with a lower Te content is deposited on the Te layer, and a layer consisting of one from Se or from Se with a very small content of Te. In this case, a layer is formed between the electrically conductive and photosensitive layers, in which the content of the photosensitive material with constant internal polarization gradually changes. The Te layer or the layer enriched by Te, adjacent to the electrically conductive layer, eliminates incomplete ohmic contact with the electrically conductive layer, and hence the delay, in charge carriers. Copper or aluminum can be diffusely distributed in a layer of Se or SeTe. In the modified photosensitive material (Fig. 4) containing insulating layers or layers 1 and 5, blocking currents located on both sides of layer 2, layer 4 with low resistivity completely eliminates the flow of charge carriers between layer 2 and layer 3. The fuiccigo of the second insulating layer can also perform a metal electrode with an oxide coating. A low resistivity layer can be obtained by vacuum deposition. Example. In the bunker 6 of the apparatus depicted in FIG. 5, the SeTe alloy weighing 16 mol.% Te is suspended, in the bunker 7 is SeTe alloy containing 4O mol% Te, and in the boat 8 is pure Te using all the components in powder form. . In the upper part of the apparatus have a thin aluminum substrate 9 with a thickness of 1 mm, covered with a film of polycarbonate resin with a thickness of 2-4 microns, and a flap 1O under it. After evacuating the apparatus, the boat 8 is heated to apply Te onto the substrate 9. After applying the Te layer with a thickness of 3mc, the boat 11 is heated to 4OO-5OOOC and from the hopper 6 is filled with SeTe alloy containing 16 mol.% Te to apply a layer on the Te, containing alloy SeTe. The application of Te is continued until a layer thickness of 5 microns is obtained, after which only the layer of SeTe alloy is applied until the thickness of the applied layer reaches 5O micron. After that, the temperature of the boat; 12 are poured before and loaded into it from the bunker 7 of the SeTe alloy containing 4O mol% Te in order to apply this alloy together with the SeTe alloy containing 16 mol% Te. When the thickness of the deposited layer containing both SeTe alloys reaches 1 micron, the deposition process is stopped and the coated aluminum substrate 9 is removed from the apparatus. Then, on top of the SeTe alloy layer, they form an insulating layer of polycarbonate resin with a thickness of 10 microns and a photosensitive material is obtained, which is shown in Fig. 4. A layer of polycarbonate resin on the aluminum substrate can not be applied. In this case, get a photo sensation of the bodies and. The material depicted in the FNG. EXAMPLE 2 A CdS powder containing 1O mol% of copper and chlorine as a co-activator is calcined at BOO ° C for 1 vl hour, 10 mol of copper and a small amount of sulfur are added, again calcined at 6OO ° C : for 15 minutes in a nitrogen atmosphere without the addition of an oddity inhibitor, a CdS: C U powder having many levels of charge capture is obtained. By roasting CdS containing 10 mol.% Of copper as an activator and chlorine as a co-activator, at 6OO ° С in TOieHHO-vl hour 11rig-o- (finely ground CdS: Cu powder with a particle size of 3 microns, which has a low resistivity. Each CdS-Ci alloy is dispersed in an organic solvent containing 7% by weight of vinilacetate. A solution of CdS: Cctivi-i 10% by weight copper is first applied to the aluminum substrate. Then both solutions are sprayed. Through a nozzle which sprayed a solution of CdS: Cu activated with 10 mol% I and, after gradual throttling, only one CdS: Cu solution is activated, 5-10 mol% of copper is activated. The total thickness of the light-conducting layer is 8 O microns, the thickness of the upper layer with constant internal polarization, and the thickness of the lower layer with low the resistivity is 1O microns (for each). On the light-conducting layer on top of the nano-ins insulation layer, a photosensitive material is obtained. Cd can be activated not only by copper, but. and gold, manganese silver, etc. The temperature and calcination time depend on the properties of the light guide material and the activator. Fabricated photosensitive materials can be reused in electrophotography without hysteresis. Any known photosensitive materials that exhibit a constant internal polarization can be used to make photocell materials. CdS, CdSe, 8e, SeTe, ZnSe, ZnS, ZnCdlS, ZtiO, PbO and other metal sulfides, anthracene, anthraquinone and other organic compounds are suitable for this purpose. A layer with a low resistivity can be formed from materials with a low resistivity, obtained by modifying the light-conducting mat & rials with constant internal polarization with activators, or from materials With a low resistivity that do not exhibit constant internal polarization and non-retarding charges. It is better to use a low resistivity material, which is a semiconductor and in which most carriers have the same polarity as in a material with constant internal polarization. In addition, any transparent high-insulating materials can be used, such as polyesters, epoxides, polyethylene, polyurethanes or polycarbonates. The subject matter of the invention is 1. A photosensitive electrophotographic material containing a transparent one: a high insulating layer, a photosensitive layer with a constant internal polarization, and an electrically conductive layer, connected as one unit, characterized in that, in order to eliminate the effect of the remaining charge, A photosensitive and electrically conductive layer is a layer with low resistivity, the composition of which is close to the composition of the photosensitive layer on the side of the electrically conductive layer. 2. Material according to claim 1, that is, with the fact that a layer of pure metal is introduced between the layer with low resistivity and the electrically conductive layer. 3. The material according to claim 1, wherein the second insulating layer is disposed between the low resistivity layer and the electrically conductive layer. 4. Material pop.1, characterized in that between the photo sensitive and electrically conductive s / m there is a layer of pure metal and a second insulating layer.

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