SU1379767A1 - Method of charging electrographic layers and device for implementing same - Google Patents

Abstract

The invention relates to a method for charging electrophotographic layers and to a device for implementing this method, which makes it possible to improve the quality of charging. The device contains a high-voltage source of alternating voltage 1. Electrodes 3 and 4 are located one below the other and are surrounded by an electrostatic screen 2. Screen 2 is electrically insulated. The electrodes 3 and 4 are connected to the terminal of the source 1 through the diodes. Electrode 4 is connected to the cathode of a high-voltage diode. The directions of the direct current diodes are opposite to each other. 2 sec. f-ly, 1 ill.

Description

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The invention is from Osits to electrophotographs, in particular, to electrophotographic mechanical engineering.

The goal of retreat is the superfluous of charge-charging.

The drawing shows a diagram of the device.

The device contains a high voltage source 1 of an alternating voltage, an electrostatic screen 2, made of electrically isolated electrodes 3 and 4, which are located one above the other and connected to source 1 through high-voltage diodes. The lower electrode 4 is connected to the cathode of a high voltage diode. The essence of the method lies in the fact that the charging of the electrophotographic layer is conducted in cyclically alternating pulsed ionic fluxes of opposite sign at a cycle time close to the time of flight of ions from the electrodes to the layer for about 10-500 cycles. Keeping the layer charged in cyclically alternating pulsed ion fluxes of opposite sign makes it possible to avoid the recombination of ions in that new gap of corona discharge. At a time of 1 point, close to the time of flight of ions through a dark gap, almost all ions of each sign reach the surface of the layer.

The alternation of the fluxes of ions of different signs makes it possible to effectively equalize the potential of the surface of the charged layer, if the number of cycles is sufficiently large less than 10). At the beginning of the charge, the current of ions of the chosen sign is set larger than the current of ions of another sign. As the potential increases, the selected sign decreases from cycle to cycle, while the current of ions of another sign increases. This process of periodically charging and discharging a layer with a predominant charge continues until the numerical values of the currents of both streams become equal to each other, and the potential of the layer reaches a predetermined value with high charge uniformity The data does not change, only slightly fluctuates around a given value. The amplitude of these oscillations is the smaller the shorter the cycle time compared with the time required for charging.

layer up to a given potential value.

Example I. Two identical corona electrodes are made for an apparatus (for charging a 1 cylinder and for transferring powder image to paper) with a working length of corona wires of about 650 mm with a diameter of each wire of 80 µm. The screen is made of 2.5 mm thick Plexiglas; small-sized high-voltage silicon poles with reverse voltage and currents of 6 kV and 0.1 μA, respectively, are used as diodes. Both electrodes are mounted, as shown in the drawing, with the following dimensions: the distance between the electrodes is 14 mm, the distance from electrode 4 to the layer is 2-14 mm, the distance from electrodes 4 and 3 to the inner surfaces of the screen is 2-14 mm. The amplitude of the alternating voltage of source I is regulated within 2-g5 kV at a frequency of Hz and a power consumption of not more than 5 watts. In the absence of resistors R and Rj (R CC J), the selenium layer is stably charged to a potential of 800 V, at R, 4 mΩ, to a potential of 1200 V at an amplitude of alternating voltage of source 1–1.4 kV. With a linear speed on the circumference of the cylinder 2, 7 min, the quality of prints is good. Increasing the amplitude of the alternating voltage to 5 kV makes it possible to increase the charging potential to 100 V and the transfer potential to 1500 V,

Example2. Mylar films of different thickness are placed on a cylindrical metal substrate: 12, 40 and 100 microns. The films are simultaneously charged by the proposed method. All films are charged to a single 800 V potential during one cycle. After five recharging cycles, the film potential does not change.

Claims (2)

1. Method of charging electrophotographic layers in a bipolar corona discharge jesymmetrical in amplitude with a electrostatic screen corona electrolyte, including the formation of an asymmetrical amplitude variable amplitude in the corona region of the electrolyzer exceeding the corona ignition potential, characterized in that, in order to increase the charging efficiency, the duration of each unipolar phase of the electric field is commensurate with the ion transit time through the discharge gap, while after each unipolar phase at the time of corona ignition in the phase other polarities form the potential difference between the screen and the corona-forming area. 2. A device for charging electrophotographic layers containing a high voltage alternating voltage source, an electrostatic shield and two discharge electrodes, which, in order to increase the charging efficiency, the electrical shield is made electrically isolated, and the electrodes are located one above the other and connected to the source terminal through high-voltage diodes, the npHbfbix directions of the diode currents being opposite, while for charging the positive polarity layer the lower electrode is connected to the high cathode voltage diode.