JPS6013179B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic method using a screen-like photoreceptor (hereinafter referred to as a screen) having fine gates.
More specifically, the present invention relates to a method for removing a change in the visible image that occurs at the initial stage of modulation when modulating the ion flow using a screen.

A static latent image (hereinafter referred to as the primary latent image) is formed on the screen through processes such as corona discharge and image irradiation, and the ion flow is modulated by the molten image, and the primary port image is formed on the chargeable member. A method of forming a corresponding new electrostatic image (hereinafter referred to as a secondary latent image) is described in, for example, Japanese Patent Publication No. 45-3032 and Japanese Patent Publication No. 48-5063. Using the above-mentioned screens, secondary latent images may be formed a plurality of times by ion flow modulation from the primary melted images on these screens to obtain images (hereinafter referred to as retention copies).

The problem in this case is that the potential of the secondary latent image formed changes depending on the number of retention copies. This change is particularly noticeable in the early stages of retention copying, and when a secondary latent image obtained by superposition tension copying is converted into a head image using toner particles, etc. under the same conditions, a density difference will occur in the formed visible image. There is. In order to solve the above problem, it is possible to adjust the corona ions by changing the bias voltage applied to the screen during initial modulation during retention copying, or by changing the applied voltage of the corona discharger for modulation. A discharge device separate from the corona discharge device has been disposed before modulation, and a certain amount of corona has been applied in advance before the initial modulation. However, each of these methods requires cumbersome setting of bias voltage during initial modulation and complicates the configuration within the drum-shaped screen. In particular, in the former method using a bias, the stability of the primary latent image on the screen is determined by two requirements: the bias voltage and the modulating corona, so there is a problem with the stability of the primary latent image. . In addition, in the latter method using other corona dischargers, the use of two dischargers that must be fixedly disposed within the rotating screen complicates the support mechanism and further reduces the diameter of the screen. It also becomes an obstacle when downsizing. An object of the present invention is to solve the above-mentioned problems of the conventional method, and to use a simple configuration and method to obtain images by forming secondary latent images multiple times using the same primary beach image. The goal is to obtain a constant image state from the initial one. The present invention achieves the above object by forming a screen in a drum shape, forming a primary latent image while rotating the screen, and performing the initial modulation of the ion flow by a modulating corona discharger. The photoreceptor is rotated idly to perform initial modulation without forming a secondary latent image on the member, and after the primary latent image is stabilized by application of corona during the idling rotation, a second latent image is placed on the chargeable member. Next, a latent image is formed to obtain an image.

According to the method of the present invention, the primary latent image is stabilized by the corona from the modulating corona discharger, so the configuration and control method are easy, and furthermore, the stabilization of the latent image can be set only by the corona discharge. Therefore, it has high stability in response to environmental changes. Further, since only a single modulating corona discharger exists within the rotating screen, the configuration is simplified. Note that the initial modulation described in the present invention means the application of modulation ions for the first time or at least several times after the formation of the primary latent image. Further, idle rotation of the screen refers to a state in which the screen is simply rotated without forming a secondary latent image on the chargeable portion. Furthermore, the chargeable member includes a sheet-like member such as an insulating drum, an insulating web, or a sheet of paper facing the screen. As will be described in detail later, specific methods of not forming a secondary submarine on the chargeable member during initial modulation include, for example, a method of not disposing the chargeable member at the modulation position while the screen is idly rotating; Alternatively, there is a method such as providing a shielding member between the screen and the three chargeable members. Hereinafter, the present invention will be described in more detail with reference to Examples and their explanatory drawings. Figures 1 to 5 show an example of the screen, and the details are described in Tokusei No. 51-341 by the applicant, and here a brief explanation of the four latent image forming steps will be given. stop.

FIG. 1 shows an embodiment of a screen to which the present invention can be applied, and a partially enlarged cross section is depicted in a formal manner. In the figure, the screen has a photoconductive member 3 and a surface insulating member 4 provided in a laminated manner on a guide member 2 having a large number of fine passage openings. A case will be described below using, as an example, a case where the light guide member 2 has a characteristic that electrons are injected into the light guide member even in a dark area. Specifically, the photoconductive member 3 contains cadmium sulfide (CdS) and zinc oxide (Z
It is a semiconductor whose main carriers are electrons such as n○). FIG. 2 shows the result of uniformly charging the insulating portion of the screen 1 to a positive polarity (10) using a known charging means such as a corona discharger 5 as a primary voltage application process. FIG. 3 shows the results of performing the secondary voltage application step and the image irradiation step substantially simultaneously.
Although a DC voltage (1) having a polarity opposite to that of the primary voltage application step is used to apply the secondary voltage, an AC voltage may also be used as the power source.

In the figure, 6 indicates a document, L indicates a bright area, D indicates a dark area, 7 indicates a light beam, and 8 indicates a corona discharger. The following FIG. 4 shows the result of irradiating the entire surface of the screen 1, and the surface potential of the screen 1 changes rapidly to form a primary latent image. 9 in the diagram
indicates a light beam from a light source means such as a lamp. FIG. 5 shows a state in which the ion flow is modulated by the primary latent image to form a secondary latent image on the recording medium.

In the figure, 10' is a corona wire of a discharger, 11 is a counter electrode member, and 12 is copy paper, on whose surface a secondary latent image is formed. Reference numerals 13 and 14 denote power supply units that form a dragon field between the corona wire and the copy paper 12 in the direction in which corona ions flow.

The copy paper 12 is disposed close to the side of the screen 1 facing the insulating member 4, and an ion current is applied to the copy paper 12 from a corona wire 10 disposed through the screen 1. At this time, an electric field due to the primary latent image of the screen 1 acts on the neck side of the image, which blocks the negative ion flow shown by the solid line Q, and conversely, an electric field acts on the dark side to accelerate the ion flow shown by the solid line 8. do. As a result, a secondary latent image is formed on the copy paper 12 in the form of a positive image of the original image. In the screen 1 having the above structure according to the present invention, since the primary latent image is formed on the insulating member, it is possible to make the electrostatic contrast based on the amount of charge of the latent image very high. Furthermore, for the same reason, the attenuation of the latent image charge formed can be minimized, making the above-mentioned IJ tension copy possible. The present invention can be applied to any screen as long as it can perform retention copying, and in addition to the above screens,
In addition to those with a two-layer structure consisting of a conductive member and a light guide member or an insulating member, there are also those with a four-layer structure, and the layer structure is not limited to that shown in FIG. 1 above. By the way, when performing retention copying using the above method, the ion flow passing through the screen 1 may be small in the initial stage, particularly in the first ion flow modulation.

If the secondary latent image formed on the chargeable member is developed under such conditions, a developed image with different density will be formed as a result. FIG. 6 shows how the current passing through the screen changes due to ion flow modulation. The amount of passing current is determined by using polyethylene terephthalate with a thickness of 12 mm as the chargeable member, and determining the current Z in the area necessary to form a secondary latent image with a contrast of 150 Y in order to obtain a visible image with an appropriate density on the member. It is a passing value. As is clear from this figure, the screen passing current value for the first modulation is significantly lower than the value for subsequent modulations. The reason for this phenomenon is that, as shown in Fig. 7, some of the modulating corona ions flow near the conductive layer on the modulation 2 corona source side of the screen, neutralizing the charges of opposite polarity near the conductive layer. Further, the modulating corona ions are charged with opposite polarity after neutralization. It is thought that this charging phenomenon is remarkable at the beginning of modulation, and thereafter the number of corona ions flowing to the above portion gradually decreases until an equilibrium state is reached2. For this reason, as shown in FIG. 6, the amount of current passing through the first modulation G is extremely low. FIG. 8 shows an embodiment of the present invention, in which the screen 1 shown in FIG.
The next latent image forming part is shown in cross section. In FIG. 3, the screen 1 is configured in a drum shape with the side where the guide member is exposed inside, and is rotated counterclockwise around a rotation shaft 15 by a driving means (not shown). A latent image forming means is arranged around the drum-shaped screen 1 in the vicinity of the screen. In the figure, 16 is a corona discharger that applies a primary voltage, and 17 is also a corona discharger, and since a secondary voltage is applied at the same time as image irradiation, the back of the discharger is made optically transparent by glass 18. It has become. Reference numeral 19 denotes a lamp for irradiating the entire surface, which is used to rapidly increase the potential of the primary static exposure latent image.

A light shielding plate 20 having a cylindrical shape is disposed inside the drum-shaped screen 1 to prevent light irradiated onto the screen from affecting the primary latent image. In the figure, 21 is a corona discharger, and corona ions are applied from the discharger 21 onto the lower insulating drum 22 through the screen 1. By applying this corona ion, the passage of the ion stream is controlled by the primary molten image on the screen 1, and as a result, a secondary book image is formed on the insulating drum 22. The insulating drum 22 includes an insulating layer 23 on its surface, and a conductive drum 24 that serves both as a support for the insulating layer 23 and as a counter electrode for the discharger 21. Although not shown, a developing means, a transfer means, and a cleaning means are sequentially provided around the insulating drum 22. For example, the secondary latent image formed on the insulating drum 22 is developed by a developing device, and then the toner image obtained by the development is transferred to a recording member such as plain paper by a transfer device. The recording member is then fixed by means such as a heat roller and used. On the other hand, the insulated drum after the transfer is prepared for the next latent image formation process by removing residual toner by a cleaning means, and then by AC corona discharge, Eliminate static electricity by applying a grounding electrode, etc. Note that the corona discharger, developing means, transfer means, and cleaning means used in conventional electrophotographic apparatuses can be used. The latent image forming section is provided with a mechanism which is an embodiment of the present invention. An operation shielding plate 25 is mounted between the screen 1 and the insulating drum 22 facing the modulating corona discharger 21 so as to be movable in the direction of the arrow along a guide groove 26. This shielding plate 25 is preferably electrically conductive, and in this case, the screen 1 and the insulating drum 22
Since a bias voltage of -04 to Uta V is applied between them, a bias of approximately Ichiro V is applied to the shielding plate 25 for the purpose of preventing discharge. The shielding plate 25 is closed as shown in the figure when the number of retention copies is the first, and after the second modulation, the shielding plate 25 is slid and placed on the insulating drum 22. Next, a latent image is formed. Next, an embodiment of the drive mechanism for the shielding plate 25 will be described with reference to FIG. 9.

In the figure, reference numeral 27 denotes an electromagnetic plunger that serves as a driving source for the shielding plate 25, and an operating portion end 28 is connected to an arm portion 30 that rotates around a central axis 29. A long hole 31 is provided at the other end of the arm member 30, and a pin 32 fixed to one end of the shielding plate 25 is fitted into the chair hole 31. Further, a tension coil spring having one end fixed is connected to the opposite side of the central shaft 29 of the arm member 30 from the plunger side. When the electromagnetic plunger 27 is energized during the above-mentioned slowing, the shielding plate 25 moves along the guide book in the direction of the arrow.
The arm member 30 is rotated in the direction of the arrow against the tension of the spring 33. As a result, the shielding plate 25 is removed in the secondary latent image forming section, and a secondary latent image can be formed on the insulating drum 22. This operation shows a state in which the shielding plate 25 in FIG. 1 moves in the direction of arrow B. Next, when the power to the plunger 27 is stopped, the arm member 30 is pulled by the spring 33 and returns to the starting position. This operation is a state in which the shielding plate 14 in FIG. 1 moves in the direction of arrow A. The shielding plate configured as described above and its operation control method are such that the shielding plate 25 is closed during the first ion flow modulation, no secondary tank image is formed on the insulating drum, and the screen and primary tank image are simply It suffices if a part of the latent image is made into modulating corona ions.

After the primary latent image has been stabilized in this manner, the plunger 27 is energized to move the shielding plate 25 to enable formation of the secondary latent image on the insulating drum. After completing the modulation a predetermined number of times, the shielding plate 25 returns to the starting position by stopping the power supply to the plunger 27. As shown by the chain line 34 in FIG. 8, by loosely fitting the shielding plate 25 with the enclosure that substantially envelops the screen, the screen is distinguished from the atmosphere except during actual modulation, so that dust can be removed. It is possible to prevent the adhesion of such substances. Further, when introducing high-temperature dehumidified air into the enclosure 34, the air can be specified in a limited area, so that the treated heated air and the like can be used effectively. FIG. 10 shows another embodiment of the shielding member. In this case, the shielding member constitutes a curved shielding plate 35 having the same zero circular shape as the screen 1, and by reciprocating rotation around the screen 1, the above-mentioned effect is achieved. This is what you get. Note that the curved shielding plate is the insulating drum 2.
It may be constructed in the same 0-circle shape as 2 and rotated back and forth. By the way, as shown in FIG. 8, a secondary latent image is formed on a chargeable part such as an insulating drum, the secondary latent image is visualized with a developer, and the image is further developed on a transfer paper or the like. In the indirect method of transferring, the above-mentioned insulated drum can be used as a shielding member. That is, in this case, a secondary molten image is formed on the insulating drum from the first time of ion flow modulation, but an image based on the first secondary latent image is not formed on the transfer paper. In this method as well, the rotation of the upper screen during the first modulation is an idle rotation. In addition, when forming a secondary latent image directly from a drum-shaped screen onto a sheet-shaped recording material such as recording paper,
The recording material need not be conveyed to the secondary latent image forming position during the first modulation. 0 As described above, the screen is configured in the form of a drum, and a corona discharger for modulation is disposed inside to form a secondary latent image.When retention copying is performed using the discharger, 1 The screen is idle rotated or rotated several times to stabilize the primary latent image with a modulating corona.

With the above configuration, it is possible to obtain a stable image from the first image as a final image. Also, for modulation.
Since the discharge device is also used to stabilize the primary latent image, it is also possible to simplify the structure inside the drum-shaped screen.
Furthermore, in order to stabilize the primary latent image using only the modulating corona,
It became possible to simplify the stabilization process.
Note that the shapes and configurations of the screen and the shielding member are not limited to those in the embodiments; for example, the shielding member may be configured with a wave guiding member on the modulation side and an insulating member on the insulating side.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially enlarged sectional view of an exemplary screen used to explain the present invention, FIGS. 2 to 4 are explanatory views of the screen's primary beach image forming process, and FIG. An explanatory diagram of the next latent image forming process. FIG. 6 is a graph showing changes in the current passing through the screen for each number of retention copies. FIG. 7 is an explanation showing the state of charge on the charging side of the screen in the first modulation. 8 is a side view of the latent image forming section of an image forming apparatus showing an embodiment of the present invention, FIG. 9 is a side view of the shielding plate drive mechanism of the above embodiment, and FIG. 10 is a side view of the shielding plate drive mechanism of the above embodiment. A side view showing an example is shown.

In the figure, 1... screen, 15...
...Rotating shaft, 22...Insulated drum, 25...
...Shielding plate, 26... Guide groove, 27...
・Plunger, 29... Central shaft, 30...
Arm member, 33... spring, 34... enclosing body,
35... Curved shielding plate. Figure 1 Figure 2 Tsutomuro Figure 4 Figure 5 Figure 7 Enshrined figure Tsutomu Figure 8 Tsutomu? illustrator'o figure

Claims (1)

[Scope of Claims] 1 Image formation performed by modulating ion flow with an electrostatic latent image formed on a screen-like photoreceptor and forming an electrostatic latent image corresponding to the latent image on the photoreceptor on a chargeable member. In law,
When the screen-like photoreceptor is configured in the form of a drum, a primary latent image is formed on the photoreceptor while rotating the photoreceptor, and initial modulation of the ion flow is performed by a modulation corona discharger, it is possible to An image forming method characterized in that initial modulation is performed by idling the photoreceptor without forming a secondary latent image on the charging member. 2. The image forming method according to claim 1, wherein a shielding member is provided between the screen-like photoreceptor and the chargeable member during the initial modulation.