SU913321A1 - Method of recording concealed electrostatic pictures on electrophotographic medium with outer dielectric coating - Google Patents

Description

The invention relates to electrography, in particular to the recording of an optical image on multilayer electrographic media with a dielectric coating.

The closest in technical essence and the achieved result is a method of recording latent electrostatic images on an electrophotographic carrier with an external dielectric coating, consisting in the primary charging of a carrier by a corona discharge of the same sign, equalizing the potential on the outer side of the dielectric coating, including exhibiting simultaneously the opposite charge of the carrier and flare. In this method, the deposition of charge on the external surface of the dielectric at overdischarge stop just at the moment when the curves of the temporal dependences of the voltage change on the light and dark areas move. Thus, the kinetics of a change in the magnitude of the surface potential due to illumination when the carrier is recharged using coronators that are not high enough is taken into account.

charging efficiency. The known method of recording most fully implements the basic principle of formation

5 electrostatic contrast on multilayer electrophotographic structures: the maximum electrostatic contrast in density of the surface charge in the mode of simultaneous exposure and reloading is formed with equipotential charging of the external dielectric surface 11].

The disadvantage of this recording method is low efficiency.

¹ . corona-charging devices, when they operate in the mode of charging the surface to a predetermined potential, the value of which should not depend on the capacity of various illuminated areas of the carrier. As a result, the rate of electrical energy supply to the photo semiconductor layer decreases and, at the same time, the efficiency of conversion of quanta into free charge carriers, which drift through the photo semiconductor layer, changes the arrangement of screening charges and leads to a change in density of 50 _tons and surface charge on the dielectric

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trick during equipotential charging of this surface. At the same time, a higher density charge accumulates on light areas than on dark ones. The result of an insufficient effective supply of electric energy * is a narrowing of the range of recorded illuminations, since the energy of the light flux at high illuminations is used inefficiently. All this leads to a deterioration in the recording quality of the hidden image.

The purpose of the invention is to improve the recording quality by varying the range of illumination, within the limits of the co-. Secondly, optical contrast can be converted to electrostatic.

This goal is achieved by the fact that in the method of recording latent electrostatic images on an electric photographic carrier with an external dielectric coating, consisting in the primary charging of the carrier by a single-character corona discharge, equalizing the potential on the outer 25 side of the dielectric coating, which includes exposing simultaneously with the discharge of the carrier opposite sign, and flare, when equalizing the potential 30 during recharging on the outside of the carrier form a uniform charge and fected extra charge carrier in the dark after recharging. 35

Example. To record using the proposed method, a multilayer electrophotographic carrier is used, containing a conductive substrate, an amorphous selenium layer with a hexagonal, a transparent layer, and an outer dielectric layer. The thickness of the dielectric layer is 20 microns, the thickness of the selenium layer is 70 microns. The recording process consists of four stages. Two types of direct current chargers are used: for the deposition of a negative charge - a corona device of direct current with a control grid, and for a deposition of a positive charge during recharging - a corona device without a control grid, tuned to the maximum corona current. At the first stage, the carrier is charged with negative charge next to –2 kV. In this case, the screening charges accumulate at the selenium – dielectric interface, since the hexagonal selenium – amorphous selenium contact is injecting for holes. The charging current through the control grid reaches 40 nA / cm ¹ . At the second stage, an optical image is projected onto the carrier, the maximum illumination of which in the lightest areas reaches several thousand lux. The recharge current density is 10 ^ nA / cm ¹ , and the exposure time through a moving coronator is about 10 ms. At the third stage, the potential of the outer surface is equalized, accompanied by a change in the density of the surface charge on this surface. Electrostatic contrast in surface charge density reaches 100 nC / cm. Before the formation of the formed electrostatic image by toner particles, the fourth stage is carried out - uniform illumination of the carrier (illumination of about 50 lx).

As can be seen from the above data, the proposed method provides greater sensitivity compared with the known and greater recording speed due to the use of corona charging devices in maximum efficiency mode.

Claims (1)

Claim The method of recording latent electrostatic images on an external dielectric Coating electrophotographic carrier, consisting in the primary charging of a carrier by a corona discharge of the same sign, equalizing the potential on the outer side of the dielectric coating, including exhibiting simultaneously with the recharge of the carrier by a corona discharge of the opposite sign, and illumination, l and h This is because, in order to improve the quality of the recording, when equalizing the potential during recharging on the outer side of the Formir carrier Cozy uniform charge and carry out an additional charge of the carrier in the dark after it is recharged.