JPH01114850A - Electrostatic recording medium - Google Patents

Abstract

PURPOSE:To increase a space between a recording electrode and a recording medium without enlarging recording dots not increasing a recording voltage by providing many independent minute electroconductive cells on the surface of a dielectric layer on a base body. CONSTITUTION:A drum shaped recording medium 10 is prepd. by covering an Al drum 3 with a dielectric layer 2 comprising polyimide, etc., forming a Cu electrode as electroconductive cells 1 thereon by printing, and finishing to a smooth surface by pressing. An electric charge is injected into the cells 1 of the medium 10 through an electroconductive roll 4 connected to a high voltage power source 11 to charge the cells to have a uniform surface potential. Then, a pulse voltage corresponding to an image signal 12 is impressed to a recording electrode 5 held at a desired space from the surface of the medium 10. Thus, the charge in the cell 1 is eliminated, and an electrostatic latent image is formed. Succeedingly, the latent image is developed reversally with a magnetic brush developing device 6, and a toner image is transferred to a common paper 13, then the recording medium is cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrostatic latent image carrier used in an electrostatic recording device, hereinafter referred to as an electrostatic recording medium or simply a recording medium.

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[Prior Art and its Problems] In general, conventional electrostatic recording methods can be broadly divided into direct recording methods and indirect recording methods.

The direct recording method does not use a recording medium, but instead creates an electrostatic latent image directly on electrostatic recording paper and then develops and fixes the image, and is used in high-speed facsimiles and the like.

This direct recording method has the advantage of simplifying the device configuration compared to the indirect method, but on the other hand, electrostatic recording paper is several to ten times more expensive than plain paper, so it has the disadvantage of high running costs. However, this point becomes increasingly disadvantageous, especially as recording becomes faster and the amount of recording paper used increases.

On the other hand, in the indirect recording method, for example, a drum or belt is formed of metal or a conductive material, a dielectric material such as resin is applied on top of the drum or belt, and a dielectric layer is formed, and the recording is placed opposite to the dielectric layer. A signal voltage corresponding to the image to be recorded is applied from the electrode to the drum or belt as a counter electrode to form an electrostatic latent image on the dielectric material, which is then developed and transferred to plain paper and fixed to form the recorded image. This is a method to obtain This method has the great advantage of reducing running costs because inexpensive plain paper can be used in addition to the recording paper. By the way, since a recording medium formed by forming a dielectric layer on a conductive drum or belt is used repeatedly, the recording medium is placed opposite the recording electrode with a gap of about 10 to 30 μm, so that the two are directly connected. It is necessary to prevent wear and deterioration that would occur if there is contact. If the gap length becomes large, the mechanism for holding and covering the recording electrode facing the recording medium becomes simpler, but the resolution of the image on the recording medium decreases, and if the gap length becomes small, the resolution increases. Another drawback is that the recording electrode holding mechanism is extremely complicated, making the device expensive, and that residues of toner used for development adhere to and accumulate in the gaps, resulting in deterioration of image quality. The gap created by the non-contact between the recording medium and the induction electrode increases the firing voltage of the recording electrode, and therefore the voltage (2) applied to the recording electrode must be increased. (2) An increase in the number of pixels impedes high-density mounting of recording electrodes due to the limitation of withstand voltage between adjacent electrodes, which in turn makes it difficult to achieve high pixel density and high-quality printing. Further, the use of high voltage circuit components makes it difficult to reduce the cost and size of the device.

Another problem is that when a recording medium is used repeatedly, the latent image left on the surface of the recording medium must be quickly erased before the next process, but it is generally difficult to remove static from the dielectric layer. Therefore, the equipment required to achieve static elimination in a short time becomes large-scale.

The purpose of the present invention is to provide a completely new recording medium that solves the above problems, and is highly reliable by increasing the gap between the recording electrode and the recording medium without enlarging the recording dot or increasing the recording voltage. An object of the present invention is to provide an electrostatic recording medium for an indirect electrostatic recording method that can achieve the following, does not require a static eliminator, is small in size, and can achieve high speed.

[Means for Solving the Problems] The present invention provides an electrostatic recording medium in which a conductive drum or belt is coated with a dielectric material, and a large number of independent minute conductive cells are provided on the surface of the dielectric material. The conductive cells correspond to recording dots, and the electrostatic latent image is formed depending on the presence or absence of charge within the cells.

The structure of a recording medium according to the present invention will be explained based on the drawings.

FIG. 1 (a) is a partial perspective view of a recording medium according to the present invention,
FIG. 1(b) is a sectional view thereof.

For the conductor substrate 1, a metal material such as aluminum is used in the case of a drum-shaped recording medium, and in the case of a belt-shaped recording medium, a resin belt with a metal film formed by vapor deposition or the like is used.

As the dielectric layer 2 formed on the conductive substrate 1, a dielectric resin film is used.

Independent conductive cells 1, for example copper electrodes, are formed on the dielectric layer 2 by a printing method.

To give an example of a drum-shaped recording medium, an aluminum drum is coated with a polyimide film (Kapton, manufactured by DuPont) with a thickness of 20 to 30 μm as a dielectric layer, and a conductive layer is roughly coated on top of it. Square copper electrodes each having a side of 85 .mu.m were printed as cells at equal intervals at 10 dots/m, and these were firmly adhered by a human press method and finished to form a smooth surface.

An example of a recording process using a recording medium according to the present invention will be explained based on a schematic diagram of an example of an electrostatic recording apparatus shown in FIG.

(1) Charging step: Charge is injected into the conductive cells 1 on the surface of the drum-shaped recording medium 10 using a conductive roll 4 with a diameter of 25 mm connected to a high-voltage power source (+500V) to charge the conductive cells 1 to a uniform surface potential v5.

No charge is injected into the insulating layer 2 existing between the electrodes of the recording medium 10, but on the contrary, it is charged slightly to the negative side by frictional charging with the conductive roll 4. In this way, since the recording medium is charged by charge injection from the conductive roll, the charging potential is not dependent on the environment and is stable, unlike the conventional method in which the rotating recording medium is charged by discharge from a corotron. It can be charged to either positive or negative polarity. Furthermore, in the case of charging using conventional devices such as corotrons and scorotrons, the charging potential decreases as the speed increases, but in the recording medium of the present invention, there is almost no speed dependence and charge injection is instantaneous. It is possible to cope with faster recording. Furthermore, there is the advantage that when the development characteristics or the discharge characteristics of the recording electrode change, by controlling the voltage applied to the conductive roll, the charging potential can be directly changed and a stable image can be obtained.

(2) Latent image forming step: A negative pulse voltage (VpN2) corresponding to the image dots is applied to the recording electrode 2, which maintains a gap of several tens of μm from the surface of the recording medium, to generate a discharge and form a latent image. do.

Most conventional latent image formation involves discharging a charge corresponding to the image onto a neutralized recording medium, but in contrast, the process using the recording medium of the present invention uses a recording medium that has been previously charged in a negative manner. A method is used to remove charges in accordance with the image. According to this method, the voltage required for discharge is divided into the voltage for uniform charging (V) and the voltage applied to the recording electrode (
Since the voltage applied to the recording electrodes can be shared by V, ), it is possible to significantly reduce the voltage applied to the recording electrodes, thereby making it possible to downsize the recording electrode drive circuit and to form the recording electrodes in a single row.

Furthermore, when using the recording medium of the present invention, it is possible to make the gap between the recording electrode tip and the recording medium wider than before.

In other words, in the conventional method, the tip of the recording electrode and the recording medium are used to discharge the charged potential on the entire surface of the recording medium in an image-like manner without impairing the resolution, and to keep the applied voltage for charge removal as low as possible. However, in the case of the present invention, since the recording medium is an independent conductive cell, discharge tends to concentrate, and the insulating layer between the electrodes is slightly damaged due to friction. Because it is charged with the opposite polarity (same polarity as the recording electrode), the spread of discharge from the recording electrode is suppressed, so the resolution is approximately twice that of conventional
It becomes possible to widen the void to about 50 μm). 5
The distance of 0 .mu.m is sufficiently larger than the average particle diameter of toner particles of 10 .mu.m, and therefore the problem of contamination due to adhesion and accumulation on the recording electrode is greatly improved.

Furthermore, since the gap can be increased, the problem of simplifying the recording electrode holding mechanism can also be solved.

FIG. 3 is a sectional view of an example of a recording electrode, in which electrode pins 15 having a diameter of 50 μm are arranged in a single row at a density of 10 dots/mtn. A pulse voltage of minus 150 V is applied from a driver circuit (not shown) in response to an image signal to cause a discharge, and the electric charge inside the cell is discharged.

The charge is dissipated and an electrostatic latent image is formed. A positive bias voltage is applied to the pin electrode when not driven to prevent discharge caused by local overvoltage of the recording medium.

In areas where the recording layer is not provided at both ends of the drum, guide rollers (not shown) installed on the recording electrode support serve as running guide rails to maintain the gap distance 16 between the electrode and the drum at a constant value of 50 μm. It is configured to do this.

In the example shown in Fig. 3, the density of the cells of the recording medium and the density of the pins of the recording electrode are the same and their positions are aligned, but the combination of the two is not limited to this. The density may be greater than 15, and in this case, the relative positions of the cells and pins do not need to be matched.

(3) Developing step: A magnetic brush developing machine 6 performs reversal development of the discharge cell portion using a positive polarity dry toner to visualize the latent image.

The developer is 1013Ω・cm (preferably 1015Ω・cm).
It is necessary to use an insulating developer with a volume resistivity of 10 to 15 μC/g.
The carrier used is a ferrite particle whose surface is coated with an insulating resin.

(4) Transfer/fixing step: The toner image is electrostatically transferred onto the plain paper 13 by the transfer corotron 7.

The transferred toner image is thermally fixed by a thermal fixing roll 8,
It becomes a permanently fixed toner image.

(5) After the transfer, the untransferred toner is cleaned from the recording medium by blade cleaning 6, and one cycle is completed.

In the process using the medium of the present invention, it is not necessary to erase the residual latent image by reducing the residual voltage of the recording medium to zero by static electricity removal before entering the next cycle. This is because residual latent images and charging unevenness caused by other development and transfer steps are compensated for by uniform charge injection up to a specified surface potential (V5) in the charging step of the next cycle.

[Effects of the Invention] As explained above, according to the present invention, it is possible to enlarge the gap between the recording electrode and the recording medium without enlarging the recording dot or increasing the recording voltage, thus achieving high reliability. is achieved, does not require a static eliminator prior to a new cycle, and because each conductive cell of the recording medium is injected with charge by contact with an energized conductive roll, the device This makes it possible to achieve smaller size and higher speed.

[Brief explanation of the drawing]

FIG. 1(a) is a partial perspective view of the recording medium of the present invention, FIG. 1(b) is a sectional view thereof, and FIG. 2 is a schematic diagram of an example of an electrostatic recording device using the recording medium of the present invention. FIG. 3 is a sectional view of the recording electrode section. Symbols in the figure: 1... Conductor substrate: 2... Dielectric layer: 3... Conductive cell; 4... Conductive roll; 5... Recording electrode: 6... Developing machine: 7 ...transcription corotron; 8
...Fixing device: 9...Cleaning blade;
10... Recording/recording medium; 11... High voltage power supply; 12
...Image transmission @:13...Recording paper: 14...Discharge: ]5...Power pin; 16...Gap; 17...
·driver. Patent applicant Fuji Xerox Co., Ltd. Representative Patent Attorney
Landlord Kunihisa

Claims (1)

[Claims] An electrostatic recording medium characterized in that a large number of independent microscopic conductive cells are provided on the surface of a dielectric layer on a conductive substrate.