JPS5917415B2 - electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention forms a primary electrostatic latent image on a photosensitive screen having a large number of openings, modulates the corona ion flow with this latent image, and creates a secondary electrostatic latent image on a chargeable body. It concerns an electrophotographic method for forming.

Conventionally, a primary electrostatic latent image is formed on a photosensitive screen having a large number of apertures using an optical image of the object to be copied, and then a corona ion stream is passed through the apertures of the photosensitive screen to generate a chargeable charge. Regarding the electrophotographic method in which a secondary electrostatic latent image is formed on the body, Japanese Patent Publication No. 832/1983 and Japanese Patent Application Laid-open No. 48/1973
It is known from publications such as No. 59840 and Japanese Patent Application Laid-open No. 51-341.

In these methods, it is difficult to increase the charging voltage of the photosensitive screen for various reasons described below, and furthermore, there is a limit to the memory property, that is, the charge retention ability of the photosensitive screen. A cross-section of a portion of a mesh used in a photosensitive screen in a conventional device is shown in FIGS. 1a-c.

In either case, a primary electrostatic latent image is formed on these screens, and then a corona ion stream is blown onto the screen 1 from a corona wire 2 as shown in FIG. Ions are attached to a chargeable body 3 such as recording paper, and a secondary electrostatic latent image is formed thereon. In order to form a primary electrostatic latent image, as shown in FIG. The photoconductive layer 4 is irradiated with light corresponding to the image.

The resistance value of the photoconductive layer 4 decreases in the area irradiated with light, and the charge in that area escapes through the conductor 5 connected to the ground, resulting in a charge distribution corresponding to the light image, that is, a first-order charge distribution. An electrostatic latent image is formed. Various methods have been considered for this charging method, but in the present invention, the primary latent image may be formed by any method, so no further description will be given here. In any case, in the case shown in Fig. 1a, since the electrostatic latent image is directly charged on the photoconductive layer, the charging voltage cannot be maintained high, and the charge decays over time (dark decay), resulting in no memory. There are drawbacks. In the device shown in FIG. 1, a transparent insulating layer 6 is provided on a conductor 5 and a photoconductive layer 4, and this insulating layer 6 is charged with an electrostatic latent image.

In this case, in order to prevent corona ions from adhering to the insulating layer 6 and destroying the electrostatic latent image when forming the secondary electrostatic latent image, a portion of the conductor 5 is exposed as shown by reference numeral 7. As shown in FIG. 3, the ions of the corona ion flow 9 from the corona beam 2 are absorbed here. However,
Because of this, when the screen is uniformly charged for the first time, the corona ions wrap around this exposed conductor portion 7 and escape from there, as shown in Figure 4, so the voltage for uniform charging must be increased. However, this also caused a problem in the memorability of the latent image, and it was not possible to create a plurality of secondary latent images from the same primary latent image. In the structure shown in FIG. 1c, a photoconductive layer 4 and an insulating layer 6 are provided on both sides of a mesh-like conductor 5, and a bias conductive layer 10 is further provided on the insulating layer 6.

First, as shown in FIG. 5, the photoconductive layer 4 is charged by a corona ion flow 9. Next, a primary electrostatic latent image is formed on the photoconductive layer 4 by irradiating a light image. Since the contrast of this electrostatic latent image is weak, that is, the electrostatic charge polarity is not reversed between the bright and dark areas of the latent image, when forming a secondary latent image, the conductor 5 and the conductive layer are Bias power supply 1 between 10
1 is connected to increase the contrast between bright and dark areas of the secondary latent image. For example, when the potential in the bright area is 50V and the potential in the dark area is 250V, if 100V is applied between the conductors 5 and 10, the flow of corona ions to the chargeable body 3 is blocked in the bright area, but they are allowed to pass through in the dark area. This results in good contrast. However, in this case as well, the charges are transferred to the photoconductive layer 4.
Since the charge is stored in Therefore, the charging voltage of the primary latent image cannot be increased much, and problems remain in the memorability of the primary latent image.

Furthermore, the structure of this screen is complicated and manufacturing is difficult. The purpose of the present invention is to increase the surface potential of the primary latent image of a photosensitive screen, and to maintain this high potential even during the formation of the secondary latent image, so that multiple secondary latent images can be generated from a single primary latent image. The object of the present invention is to provide a method capable of forming a latent image.

In the electrophotographic method of the present invention, the entire conductive member having a large number of openings is covered with a photoconductive member, and an insulating layer is provided on a part of this layer. When a secondary latent image is formed and a secondary latent image corresponding to the primary latent image is formed on another chargeable body by spraying corona ions through this photosensitive screen using a coroch charger, the corona ions are sprayed onto the photosensitive screen. This method is characterized in that it is performed while irradiating the photosensitive screen with light to prevent undesired accumulation of ions.

The present invention will be described in detail below with reference to the drawings. Figure 7A
, b show cross-sectional views of examples of photosensitive screens used in the method of the present invention. In the embodiment shown in FIG. 7a, the entire surface of the mesh-like conductor 5 is covered with a photoconductive layer 4, and an insulating layer 6 is applied on one side thereof. In the example shown in FIG. 7b, the entire surface of the mesh-like conductor 5 is covered with a photoconductive layer 4 consisting of two parts.
, 4' and an insulating layer 6 on top of one photoconductive layer 4.
be coated with. The thickness of these layers varies depending on the method of forming the primary latent image, but is approximately 5 to 100 microns. Now, in order to form a primary latent image using the photosensitive screen shown in FIG. 7a, as shown in FIG. After performing charging according to the image, uniform exposure is performed to form a primary latent image. In this way, when light image irradiation and charging are performed simultaneously, the charging efficiency of the dark portion of the primary latent image can be increased, and a primary latent image having an extremely high surface potential can be formed on the insulating layer 6. . Furthermore, since the entire surface of the center conductor 5 is covered with the photoconductive layer 4, when it is charged as shown in FIG. 8, as in the case of the example explained in FIG. 2b and FIG.
Since corona ions do not wrap around the conductor, it is possible to further increase the surface potential compared to the example shown in FIG. 2b. The screen shown in FIG. 7b also provides the same effect as in FIG. 7a. Since the screen is further divided into 4 and 4" parts, an even better primary latent image can be obtained. After forming the primary latent image on these screens, the 9th
As shown in the figure, when corona ions are sprayed, the corona ions pass through the photosensitive screen and become secondary to the chargeable body 3 due to the action of the promoting electric field formed between the insulating layer 6 and the photoconductive layer 4 in the dark area. A latent image is formed, but if DC corona discharge is performed at this time, ions that are blocked from passing through the screen will accumulate on the photoconductive layer 4, deteriorating or destroying the primary latent image.

This is particularly important when forming a large number of secondary latent images. Therefore, in the present invention, as shown in FIG. 9, when forming a secondary latent image, the lamp 1 is
2 uniformly irradiates light to lower the resistance value of the photoconductive layer 4, allowing trapped ions to escape through the conductor 5 to prevent charge accumulation.

In this way, according to the present invention, corona ions when forming a secondary latent image are not accumulated on the screen.
The secondary latent image does not deteriorate, and since the primary latent image is formed on an insulating layer with a high charge retention ability, it is stably retained for a long time.

Therefore, a large number of high-quality secondary latent images can be formed from a single primary latent image. Furthermore, since the screen has a simple structure, it is easy to manufacture. The present invention is not limited to the embodiments described above, but can be modified in many ways. The method of performing primary charging includes (a) primary uniform charging;
There are methods that involve light image irradiation, simultaneous reverse polarity charging, and uniform exposure, and methods that involve (d) light image irradiation, simultaneous charging, and uniform exposure. When the bright and dark areas are charged with opposite polarities, a corona charger with the same polarity as the dark area of the primary latent image is used when forming the secondary latent image, and by adjusting the amount of light, a screen of corona ions can be created. The screen potential can be appropriately set by controlling the amount of charge on the screen.

By doing this, the amount of corona ions passing through the screen can be adjusted, and the contrast of the secondary latent image, etc. can be adjusted freely. Further, in the above example, when forming a primary latent image, corona ions and a light image were irradiated from the insulating layer 6 side of the photosensitive screen, but both or one of these may be performed from the opposite side of the photosensitive screen. You can also do that. Furthermore, during the formation of a secondary latent image, both or one of corona ion and uniform exposure can be performed from the insulating layer side of the photosensitive screen. However, in this case, it is necessary to consider the polarity of the corona ion.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of a conventional photosensitive screen mesh, Figure 2 is a line diagram showing the method of forming a secondary latent image, and Figure 3 is a diagram showing the method of forming a secondary latent image.
The figure is a diagram showing how a secondary latent image is formed by the screen shown in Figure 1b, Figure 4 is a diagram showing how a primary latent image is formed, and Figure 5 is a diagram showing the screen shown in Figure 1c. FIG. 6 is a line diagram showing how a secondary latent image is formed, FIG. 7 is a cross-sectional view showing the structure of a screen used in the electrophotographic method of the present invention, FIG. 8 is a diagram showing how a primary latent image is formed on the screen shown in FIG. 7;
FIG. 9 is a diagram showing how a secondary latent image is formed while irradiating a screen with light according to the method of the present invention. 1... Screen, 2... Corona charger, 4... Photoconductive layer, 5... Conductor,
6... Insulating layer, 10... Light source (lamp).

Claims (1)

[Claims] 1. Forming a primary latent image on the insulating layer of a photosensitive screen constructed by covering the entire conductive member having a large number of holes with a photoconductive member and providing an insulating layer on a part of this layer. ,
When a corona charger sprays corona ions through this photosensitive screen to form a secondary latent image corresponding to the primary latent image on another chargeable body, corona ions are undesirably accumulated on the photosensitive screen. An electrophotographic method that is characterized in that it is performed while irradiating light onto a photosensitive screen to prevent