SU866531A1 - Method of obtaining latent electrostatic image - Google Patents

Description

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The invention relates to electrography and can be used in electrophotographic copying machines that use intermediate image carriers — photoreceptors containing a conductive substrate, a photoconductor layer, and a dielectric layer. A known method of forming a latent image on a selenium photoreceptor with a dielectric layer, comprising charging the photoreceptor in a cross-section of the JJ corona in the light, recharging in the positive corona and subsequent exposing 1D.

In connection with the creation of a relief of an image formed by a positive charge, this method in principle makes it possible to obtain a bipolar latent image, which, unlike the monopolar one, has a lower background level and higher resolution.

However, during cyclic operation of the apparatus, it is difficult to realize a bipolar image due to the accumulation of positive charge at the boundary between the selenium and dielectric layers. In addition, during cyclic operation, the sensitivity of the layer to

the active radiation and the time of the Tammine Discharge due to the accumulation of positive charge at the boundary between the selenium layer and the substrate, which causes the photoreceptor fatigue.

The accumulation of a significant positive charge on the substrate leads to the formation of a local strong electric field in the selenium layer.

10 on the substrate, as a result of which the generation of free charge carriers on the substrate increases sharply and the rate of dark decay of positive charged Svlenovo increases; 10

5 layers Another consequence of the accumulation of positive charge on the substrate is a decrease in the actual potential difference in the rest of the selenium layer, which is charged before

20 value, positive potency. The latter is the reason for the sharp decrease in the sensitivity of the selenium layer to highly absorbable active rays.

25 The purpose of the invention is to improve the image quality.

The goal is achieved by the fact that, before charging with a negative coring, a charge is produced

30 of the carrier with positive corona discharge with simultaneous illumination by its weakly absorbing actinic radiation with a wavelength of not less than 600 microns

The photoreceptor is corona-charged to a predetermined value of positive potential and simultaneously irradiated with weakly absorbing actinic light. Thereafter, the photoreceptor is recharged in the coronal size to a given value of negative potential and simultaneously irradiated with highly absorbable actinic light, then the photoreceptor is recharged again in the dark to a given value of positive potential, and then exposed to highly absorbable actinic light. A charge combined in time with the irradiation of a positively charged photoreceptor with weakly absorbed actinic light leads to the dispersion of a positive volume charge on the substrate and to the fatigue of the selenium layer. The need to use low-absorbing actinic light is dictated by the fact that only low-absorbing light is able to penetrate the selenium layer to the substrate. On the other hand, this light is strongly absorbed in a relatively thin part of the selenium layer near the substrate, just in the zone of formation of a positive volume charge. The absorption of light by the said thin part of the selenium layer near the substrate is due to a considerable degree of selenium polymerization in this region.

Figure 1 shows the distribution of charges and potentials in the photoreceptor during charging with simultaneous illumination with weakly absorbed light (Stage 1); figure 2 shows the distribution of charges and potentials in the photoreceptor during recharging with simultaneous illumination with strongly absorbable light (Stage 2) ; Fig. 3 shows the distribution of charges and potentials in the photoreceptor during charging in the dark (stage 3); Fig. 4 shows the distribution of charges and potentials in the photoreceptor when exposed to highly absorbable light (stage 4).

The electrophotographic carrier (FIG. 1) consists of an aluminum substrate 1 with successively deposited selenium layer 2 and a dielectric film 3. The selenium glassy layer 2 at the interface with the substrate contains a high polymer layer 4.

The distribution of the potentials of selenium 2 and dielectric 3 layers of the photoreceptor after the first stage of charging to a potential of + -25008 while simultaneously irradiated with weakly absorbed (crane) actinic light with a wavelength of 660-800 nm is shown in the first stage. The time of the first stage is about 0.7 s. Red light is not absorbed in the amorphous layer and is almost completely absorbed only in interlayer 4. The absorption of red light in interlayer 4 is accompanied by the generation of positive and negative free charge carriers, which ensures the charge of the dielectric layer in a short time and the resorption of positive volume charge at the boundary amorphous selenium with high polymer selenium.

In the second stage, the distribution of charges and potentials after the second stage of negative charge of DO-2500V is shown, with simultaneous irradiation with strongly absorbable actinic light with a wavelength of 380-500 nm. At this stage, there is no accumulation of positive volume charge near layer 4.

In the upper part of the selenium layer, when irradiated with strongly absorbing light near the selenium – dielectric layer, carriers are generated and under the action of an electric field electrons are injected through the layer to the substrate and positive charges accumulate at the interface, neutralizing the negative charge of the dielectric layer.

At the third stage (Fig. 3), the photoreceptor is recharged in the dark to a potential of + 500V. In this case, the layer due to positive charges at the dielectric – selenium interface acquires a potential with respect to the substrate equal to + 25DOB. The positive charges at the interface are partially balanced by the negative charges on the dielectric. Since the dark potential drop in the selenium layer is small, there is still no volume charge near the polymer layer.

In the fourth stage, the exposed areas correspond to the energy of illumination in the order of 10 J / cm, and the dark areas were illuminated 5-6 times weaker. As a result, a monopolar potential relief of 800V is formed. the selenium layer and the resulting ezipolny relief from -300 to 300 V on the outer surface of the dielectric.

Using the proposed method for obtaining a latent image on a photoreceptor with a dielectric layer provides, in comparison with the known method, a stable bipolar latent electrostatic image with a low background level and high resolution during long-term operation of the device.

Claims (1)

1. Mayatigh K. IEEE Trans on Electr, Dev. V, EO-19, W 4, 1972, p, 405. tun 1 -4 (8) 1 y / w apm 11m clem