JPS5922936B2 - electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel electrophotographic method using a screen-like photoreceptor (hereinafter simply referred to as a screen) having a large number of fine passage apertures.

A method of forming an image by using a screen in which a photoconductive layer is provided on a conductive layer obtained by metal mesh or etching, applying a corona ion flow to the screen at the same time as image exposure, and causing the ions to pass through the screen in an image form. is a special public official in 1974-8.
There are descriptions in Publication No. 32, Japanese Patent Publication No. 46-39318, etc. These known methods may have difficulty producing commercially acceptable images for reasons discussed below. Other image forming methods using screens include
Although described in Japanese Patent Publication No. 8-5063 and Japanese Patent Publication No. 50-18782, etc., in these methods, it is not possible to apply a simple configuration in which the corona ion flow is modulated at the same time as image exposure, so the device configuration is It becomes complicated.

An object of the present invention is to make it possible to obtain an image with sufficient resolution by modifying the screen configuration and the method of applying a corona ion flow for modulation, performing modulation at the same time as image exposure.

The present invention that achieves the above object includes a photoconductive layer existing on one side, a first conductive layer supporting the photoconductive layer, and a first conductive layer that supports the photoconductive layer.
A second conductive layer is provided to the conductive layer via an insulating layer, and the second conductive layer is provided on the opposite side of the screen from the photoconductive layer, and the image is irradiated onto the screen and modulated at the same time. It provides a corona ion flow to form an image. As a method for modulating the ion flow, two types of voltages are alternately applied between the first conductive layer and the second conductive layer to modulate AC or DC corona ions.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings and a conventional example. Figure 1 shows ion modulation using a conventional screen. In the figure, 1 is a screen. The screen consists of two layers: a conductive layer and a photoconductive layer. It consists of:

While exposing the screen 1 with a light image by an image exposure means (not shown), a corona ion flow is applied from the corona discharge wire 2 to form an electrostatic latent image on the recording medium 3 having charge retention ability. Indicates the state in which In the figure, E1 and E2 indicate high voltage power supplies, the broken line indicates an electric field, and the corona ion flow advances in the direction of the electric field to form a latent image. According to the above conventional method, the dark side of the screen (black part of the image) is charged, and as a result, the ion flow is not absorbed by the screen 1 and reaches the recording medium 3, but on the other hand, the ions on the bright side (white part of the image) are charged. The charges thus carried flow into the conductive portion of the screen 1, and fewer ions reach the recording medium 3. Due to the above phenomenon, an electrostatic latent image is formed on the recording medium 3. However, when using the above method, since the screen 1 is charged in the dark area, at the boundary between the dark area and the bright area of the image, an electrostatic latent image is formed on the recording medium 3.
As shown in the figure, the electric field is bent toward the bright side. As a result, at the boundary of the image, unnecessary ions flow into areas where ions should not be allowed to pass, rather than areas where they should be allowed to pass. Furthermore, if too many modulating ions are supplied on the bright side, the number of ions passing through increases, and as a result, the boundary of the latent image formed on the recording medium 3 becomes unclear. Furthermore, in the case of a thin line image, most of the corona ions flow into the image bright areas on both sides of the line image area of the screen, making it difficult to form a line image latent image. Considering the above phenomenon, the potential of the screen on the side that supplies the corona ion flow will be required to be always in a uniform state.

The present invention fulfills the above requirements and will be described in detail below with reference to principles and examples. FIG. 2 shows the configuration of a screen used in the electrophotographic method of the present invention.

As shown in the figure, the screen 4 includes a first conductive layer 5 having a large number of passage openings of about 100 to 400 meshes, and
On the other hand, there is a second conductive layer 7 with an insulating layer 6 in between, and a photoconductive layer 8 formed on the side opposite to the insulating layer 6 of the first conductive layer. 8, and the second conductive layer 7 faces on the other side. The material for the conductive layer 5 constituting the screen 4 may be a metal plate with good conductivity such as stainless steel, copper, aluminum, tin, etc., which may be formed by etching a countless number of minute openings, electroplating, or the like. A metal net made by knitting thin metal wires as described above may be used. Materials for the insulating layer 6 include organic insulating substances such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic resin, polycarbonate, silicone resin, fluororesin, epoxy resin, and copolymers and mixtures thereof. Materials such as solvent-based, thermopolymer, and photopolymer types can be used. These materials are formed by spray coating or vacuum deposition. Conductive layer 7 on the insulating layer 6
The materials and forming methods include Al, Cu, Au, In,
It is provided by vacuum evaporation of Ni or other metals, or by spray coating a mixture of a conductive resin containing a quaternary ammonium salt, or a mixture of carbon powder, fine metal powder such as Ag or Cu, and a binder resin. Materials for the photoconductive layer 8 include S, se, pbO.
An alloy or intermetallic compound containing S, Se, Te, As, Sb, Pb, etc. can be used, and these are provided in the conductive layer 5 by vacuum deposition. Regarding the materials used for these screens, please refer to the Japanese Patent Application Laid-Open No. 1983-1973 by the applicant of this patent.
This is also stated in Publication No. 89042. In the screen 4, the first conductive layer is not necessarily used as the base, and a net woven from insulating fibers such as nylon or Tetron may be used as the base. FIG. 3 shows the configuration of a screen 9 made of such an insulating fiber as a base material. In the figure, the screen 9 includes an insulating layer 10 as its base, a first conductive layer 12 and a second conductive layer 13 provided on both sides thereof, and a first conductive layer 12 and a second conductive layer 13 provided on both sides thereof.
A photoconductive layer 14 is provided on the conductive layer 12 side. By the way, in the above-mentioned screen 4, charged particles such as corona ions and optical images are applied from the side where the conductive layer 7 is present, so the conductive layer 7, the insulating layer 6, etc. must be translucent, so that the photoconductive layer 8 can be Although it is preferable to be electrically conductive, it does not necessarily have to be translucent. During image formation, the screen 4, corona ion source, exposure means, recording medium, etc. are arranged as shown in FIG. However, according to the screen used in the present invention, since the conductive layer faces the corona ion source side, it has the same potential as the ion source side of the screen, so the bending of the electric field as shown in Figure 1 does not occur. There is no. FIG. 4 shows the amount of ions passing through the screen 4 as the surface potential Vs of the photoconductive layer 8 when modulating corona ions are applied from the second conductive layer 7 side using the screen 4 having the configuration shown in FIG. It is shown as a function of the difference in potential Vb of the second conductive layer 7. When the applied corona ions are negative (D), the right side of the horizontal axis is positive, and conversely, when the applied corona ions are positive, the right side is positive. is negative. FIG. 5 shows how modulated corona ions are applied and the voltage applied to the second conductive layer 7 when forming an image using the screen 4.

In the above figure, the upper side shows the voltage waveform applied to the corona discharge electrode to generate alternating current corona discharge for modulation.
On the other hand, the lower graph shows an example of the voltage waveform applied to the second conductive layer 7 in synchronization with the AC corona discharge. In the examples, a case is shown in which the photoconductive layer 8 is used while being positively charged, but when it is used while being negatively charged, the polarity may be reversed. Further, for convenience, the potential of the first conductive layer 5 of the screen is set to zero, and this will be considered as a reference. When applying a voltage to the first conductive layer 5, it is only necessary to shift the voltage value. Figure 6 is the 5th figure above.
The figure shows the change in surface potential of the photoconductive layer 8 of the screen 4 when the voltage shown in the figure is applied. Assuming that a positive corona discharge occurs from the modulating AC corona discharger, a voltage of 1 is applied to the second conductive layer 7 in FIG. The surface potential D of the bright portion of the image of the layer 8 increases as it approaches V. In the bright areas of the image, the photoconductive layer 8 becomes conductive due to exposure, and the value V becomes closer to zero.
It becomes L. The reason why the potential rises in a stepwise manner is because it is charged only during periods when positive ions are applied, and not during periods when negative ions are applied. Note that when negative ions are applied, a voltage as shown in FIG. 1 is applied between the screen and the recording medium, and since the negative ions are absorbed into the second conductive layer 7, photoconductive It does not erase the positive charge of layer 8. The photoconductor 8 is charged using the positive component of the AC corona discharge as described above, but recording on the recording medium is performed using the negative component of the AC corona discharge.
f) It is carried out by the ingredients. When negative corona discharge occurs, the potential b of the second conductive layer 7 is at a potential V2 between VD and VL. Since D is positive with respect to V2, a large amount of negative ions pass through, as shown in FIG. 4, and since L is negative, no ions pass through. As described above, a clear electrostatic latent image matching the optical image can be formed on the recording medium. In addition, there is a conductive layer on the ion source side, and for the reason mentioned above, the electric field from the ion source to the screen acts perpendicularly, making it possible to sharpen the boundaries between bright and dark areas and create fine line latent images. Make it. In the above description, the case of using an alternating current corona discharge was described, but in the above description, the modulated ion flow passing through the image dark part of the screen forms a latent image on the recording medium, which is then developed.

Next, a case where direct current is used for modulating corona discharge will be explained.

In this case, an alternating current voltage is applied to the screen and the recording medium. Figure 7 shows when an image is formed by applying positive DC corona discharge at the same time as image exposure, with the voltage applied to the recording medium on the upper side and the waveform of the voltage applied on the conductive layer of the screen on the lower side. Indicated. That is, when a voltage of V1 is applied, the surface potential of the photoconductive layer 8 of the screen 4 in the dark part of the image approaches V1, similar to the steps shown in FIGS. 5 and 6 above. At this time, a positive voltage is applied to the recording medium with respect to the conductive layer of the screen 4, and the positive corona ions do not reach the recording medium. On the other hand, when voltage V2 is applied to the screen, a negative voltage is applied to the recording medium, so positive corona ions are applied to the screen in the bright area of the image where the voltage is more negative than V2. to form a latent image on the recording medium. Since the potential of the photoconductive layer in the dark part of the image is more positive than 2, positive corona ions are repelled and cannot pass through the openings of the screen 4. In this way, the ion flow passes only through the screen openings corresponding to the bright areas of the image, and the latent image is developed to obtain a negative image. In addition, in the above modulation method, a vertical electric field acts from the corona ion source to the screen, so
The boundaries between bright and dark areas of the image appear clearly, and a good line latent image can also be obtained. [Example 1] 3 woven with 30μ stainless steel wire as a screen
A vinyl chloride resin solution was spray-coated on one side of the first conductive layer made of a 00 mesh wire mesh and dried to form an insulating layer with a thickness of 12 μm.

Next, photoconductive Cd is applied to the conductive layer from the side opposite to the insulating layer.
Spray a solution of S powder dispersed in Sl resin,
The photoconductive layer was constructed to have a thickness of μ. Further toward the insulating layer side 100
Palladium was vacuum-deposited to a thickness of 1 angstrom to form a second conductive layer. The screen was stretched on a metal frame and supported on a flat surface, and electrostatic recording paper was placed facing the photoconductive layer of the screen and 5 mm from the screen. A voltage of -3k was applied to the conductive layer portion of the electrostatic recording paper using an electrode, and the first conductive layer of the screen was grounded. In the above condition, the image is irradiated onto the screen with a light intensity of 40 lux in the bright part of the image, and 7 at 100 Hz (Hertz).
An alternating current corona discharge is applied for 0.2 seconds from a discharger of k. At this time, the second conductive layer of the screen has - when negative corona occurs.
A rectangular wave voltage of 200 V and -70 V when a positive corona occurred was applied. When the electrostatic recording paper was then developed with a liquid developer containing negatively charged toner, a positive image was obtained that clearly reproduced fine line images and boundaries between light and dark areas. The above modulation state will be explained with reference to FIGS. 8 and 9.

In the figure, reference numeral 4 denotes a starne whose construction is the same as that described in FIG. 2 above. Further, 1 indicates a corona wire to which an AC voltage is applied, 3 indicates a dark area of the recording member D, L indicates a bright area, arrow α indicates a blocking electric field, and arrow β indicates an accelerating electric field. FIG. 8 shows the case when a positive voltage is applied to the corona wire 2. At this time, -70V is applied to the second conductive layer as shown in the figure, and the photoconductive layer 8 on the dark side is charged to -150, for example, between 200 and -70V, and the photoconductive layer 8 on the bright side No. 8 has a surface potential of O. Therefore, as shown in the figure, a blocking electric field α for the ion flow (dashed line) acts in the bright area, and an accelerating electric field β acts in the dark area, causing the recording medium to
A positive (1) latent image is formed thereon. On the other hand, FIG. 9 shows a case where a negative (d) voltage is applied to the corona wire 2. In this case, since -200V is applied to the second conductive layer 7, an interfering electric field α acts on both bright and dark areas, and as a result, negative (
f) Ions flow into the second conductive layer and do not reach the recording medium 3. Therefore, a latent image is formed on the recording medium 3 by positive corona ions. [Example 2] Using the same screen as in Example 1, recording paper, screen, and discharger were arranged in the same manner, and an alternating current corona discharge of 7K was applied from the discharger for 0.2 seconds at 100Hz.

At this time, the voltage applied to the second conductive layer was +200V when a positive corona occurred, and -80V when a negative corona occurred.On the other hand, a voltage of +3k was applied to the electrostatic recording side electrode, and the ion performed modulation. When the resulting latent image on the record was developed with the above developer, a clear negative image was obtained as in Example 1 above. [Example 3] Using the same screen as in Example 1 above, negative corona discharge was applied at the same time as image irradiation in the same arrangement.

The negative corona discharge was carried out at 100 Hz and -8K for 0.2 seconds, while the image irradiation was carried out at a light intensity of 40 lux in the bright part of the image. The first conductive layer of the screen was grounded, and voltages of -1k, -200V, 1+3kV, and -100V were alternately applied to the electrode for electrostatic recording paper and the second conductive layer of the screen, respectively. As a result of developing the latent image obtained on the electrostatic recording paper with a liquid developer containing positively charged toner, a clear negative image could be obtained. Next, one embodiment of the electrophotographic method according to the present invention will be explained with reference to FIG.

The illustrated device 15 has a stationary document table and a screen covering the entire exposure surface. In the figure, 16 is an outer box of the apparatus, and 17 is a screen stretched at the exposure position described in FIG. 2, and the screen 17 is stretched with the second conductive layer facing upward. 18 is a corona discharger for modulation, 19 is an original table, 20 is a lamp for illuminating the original, and 21 is a lens. The original placed on the original table 19 is irradiated by the lamp 20, and an image is formed on the screen 17 by the lens 21. be done.

Further, on the photoconductive layer side of the screen, a rolled electrostatic recording paper 21 serving as a recording medium and a counter electrode 22 are arranged. The recording paper 21 is placed at a latent image forming position by rollers 23 and 24, and after the latent image is formed, the recording paper 21 is cut by a cutter 25, and by rollers 26, 27, and
0, the image is discharged via the fixing device 31 to a tray 32 outside the machine. The apparatus 33 in FIG. 11 has a movable document table and a starne for slit exposure.

In the figure, numeral 34 denotes a machine box of the apparatus 33, and numeral 35 denotes a screen, which has the structure shown in FIG. In the figure, reference numeral 36 denotes a movable document table, and the document on the document table 36 moving in the direction of the arrow is illuminated by a lamp 37, and is imaged onto the screen 35 through an in-mirror lens 38. A corona discharger 39 for modulation is fixedly installed on the document side of the screen 35, and the modulated corona ion flow is formed on an insulating drum 40, which is a recording medium, and rotates in the direction of the arrow in synchronization with the document table. Ru. The latent image on the insulating drum 40 is developed by a developing device 41, and then a plain paper transfer material 42 is sent out by a paper feed roller 43, and the developed image is transferred onto the transfer material 42 by a corona discharger 44. The transfer material is separated from the drum 40 by the post-transfer separation means 45 and transferred to the fixing device 46 by the roller 47.
and later discharged to a tray 48 outside the apparatus. Note that residual toner is removed from the insulating drum 40 by a cleaning means 49 in preparation for the next image forming process. In addition, in the embodiment apparatus shown in FIGS. 8 and 9, the voltage applied to the modulation dischargers 18, 39, the starne 17, 35, the counter electrode 22, the insulating drum 40, the amount of light during exposure, etc. are the same as in the above embodiment. etc. apply. As described above, the present invention makes it possible to perform modulation simultaneously with image exposure, clearly reproduce mirror fields in bright and dark areas of the image, and also clearly reproduce linear images.

Therefore, there is no need to arrange a complicated latent image forming means near the screen, and furthermore, since modulation is performed simultaneously with exposure, it is possible to increase the image forming speed, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the state of conventional ion modulation, FIGS. 2 and 3 are partially enlarged sectional views of the screen used in the present invention, and FIG. 4 is modulation performed by the Stareen 4 configured in FIG. 2. Figure 5 shows the voltage applied to the screen when alternating current corona discharge is used as the modulating corona ion. Figure 6 shows the state of the latent image formed on the screen. Figure 7 is a graph showing the relationship between the voltage applied to the screen and the recording medium when DC corona discharge is used as the modulating corona ion, and Figures 8 and 9 are graphs showing the relationship between the voltage applied to the screen and the recording medium side.
The figure is a process explanatory diagram showing the modulation state in Example 1,
FIGS. 10 and 11 are cross-sectional views of the apparatus according to the present invention, schematically showing the configuration of the apparatus according to the present invention. In the figures, 1...screen, 2...corona discharge wire, 3...・
...Recording medium, 4,9...Screen, 5,
12...First conductive layer, 6,10...Insulating layer, 7,13...Second conductive layer, 8,14...
...Photoconductive layer, 17, 35...Screen, 18,39...Discharger, 21...Electrostatic recording paper, 22... Electrode, 40...Insulated drum.

Claims (1)

[Claims] 1. A method of forming an image using a screen-like photoreceptor having a large number of fine passage openings, including a photoconductive layer existing on one side, a first conductive layer supporting the photoconductive layer; a second conductive layer that is present on the opposite side of the screen from the photoconductive layer; An electrophotographic method in which corona discharge is applied as a modulating ion flow simultaneously with image irradiation, two types of voltages are alternately applied between the first conductive layer and the second conductive layer, and the corona ion flow is modulated. 2 Using AC corona discharge as the modulation ion flow,
As a potential difference between the first conductive layer and the second conductive layer, two types of voltages are applied alternately in synchronization when positive (+) corona and negative (-) corona occur in the AC corona discharge. An electrophotographic method according to claim 1. 3 Using DC corona discharge as the modulated ion flow, the potential difference between the first conductive layer and the second conductive layer and the potential difference between the conductive layer and the chargeable member are synchronized with each other and
The electrophotographic method according to claim 1, which is carried out by alternately applying different voltages.