JPS5911907B2 - Insulating liquid removal device - Google Patents

Description

[Detailed Description of the Invention] The present invention utilizes corona discharge to remove excess insulating liquid adhering to transfer photoreceptors, transfer materials, photosensitive sheets, etc. during various electrophotographic copying processes. This invention relates to an insulating liquid removal device.

More specifically, the present invention develops an electrostatic latent image formed on the surface of a transfer photoreceptor with a liquid, and then removes excess liquid developer that adhered to the transfer photoreceptor before transferring it to a transfer material. Insulating properties that remove excess liquid developer that has adhered to the post-transfer material or the excess liquid developer that has adhered to the surface of the photosensitive sheet after developing the electrostatic latent image formed on the surface of the photosensitive sheet and before fixing. This invention relates to a liquid removal device. In a transfer-type wet-type electrophotographic copying device (in general, an electrostatic latent image on the surface of a photoreceptor is developed with a liquid developer, the developed image is transferred to a transfer material, and the transferred image on the transfer material is fixed). The photoreceptor is cleaned of residual developer remaining on the photoreceptor after transfer, and the cleaned photoreceptor is reused.

In such a conventional electrophotographic process, the copied image on the transfer material causes fogging even in the bright areas of the original image, and also causes blurring of the image, making it extremely unclear and difficult to see. This is because when the electrostatic latent image on the surface of the photoreceptor is developed, excess developer is attached to the surface, and developer usually contains at least toner and carrier, and this toner Floating toner in areas other than the image area may be fixed as is, or in the transfer method, toner may be transferred and adhered to non-image areas during transfer, or toner attracted to the image area may be transferred to the image area due to pressure during transfer, etc. It is thought that this is due to the adverse effects of the carrier flowing out on the carrier flow.For this reason, in the past, a squeezing roller or the like was placed on the photoreceptor after development to squeeze out the excess developer. However, the use of this squeezing roller inevitably causes image disturbances as well as the transfer process described above, and the use of a squeezing roller to remove excess developer on the transfer material also causes similar image disturbances. Furthermore, after the electrostatic latent image on the surface of the photosensitive sheet is developed with a liquid, if the excess developer on the photosensitive sheet is removed by a squeezing roller, it is inevitable that image disturbances will occur.

In order to solve the above-mentioned problems, an improved insulating liquid removal device has been proposed and implemented, which applies corona discharge to the excess insulating liquid adhered to the surface of the holding member in conventional electrophotographic copying machines to squeeze out the liquid. ing.

That is, in an electrophotographic copying apparatus, a transfer photoreceptor or a photosensitive sheet has excess developer attached to it after liquid development is completed, and a transfer photoreceptor or photosensitive sheet has excess developer attached to it after completion of transfer of a liquid developed image. A corona discharge of a desired polarity is applied from the surface of a holding member such as a transfer material to which an insulating liquid is attached, thereby removing the insulating liquid.

That is, by moving the corona discharger relative to the surface of the insulating liquid and sequentially charging it from one side to the other, the liquid surface becomes depressed and the squeezing effect is removed. As a result, the remaining liquid is almost completely pushed out and removed. The insulating liquid squeezed out as described above is then removed by liquid removal means such as suction or gravity.

In the case where the insulating liquid on the holding member is squeezed and removed by corona discharge, the discharge polarity will be described.

First, when the target subject to the aperture action by corona discharge is a developer that has developed an electrostatic latent image on the surface of a photoreceptor, the process is as follows. The charging polarity due to corona discharge is preferably the same as the polarity of the toner used to develop the electrostatic latent image on the surface of the photoreceptor. That is, since the developer is squeezed while the developer toner is pressed against the surface of the photoreceptor by the electric charges generated by corona discharge, the squeezing effect can be obtained without disturbing the image. However, if the electrostatic latent image on the surface of the photoreceptor strongly attracts toner, the charging polarity by corona discharge for removing the developed image can be carried out satisfactorily without disturbing the image in any way even if the polarity is opposite to that of the developed toner. It is. Therefore, although some selection of conditions may be required, it can be said that good effects can be obtained with either polarity. Next, when squeezing and removing an insulating liquid such as a cleaning liquid, the corona discharge polarity can be selected quite freely. The above is not limited to applying direct current to corona discharge, but if the surface of the insulating liquid can be charged by applying alternating current voltage, sufficient aperture removal effect has been obtained in experiments, so alternating current voltage application is also applicable. be. In order to achieve the above-mentioned effect of removing the insulating liquid on the holding member by corona discharge more efficiently, it is necessary to add additional means to the ordinary corona discharger.

Possible methods for this include increasing the voltage applied to the corona discharge electrode or bringing the corona discharge wire closer to the holding member. However, these methods inevitably cause the photoreceptor to be strongly charged, causing undesirable conditions such as spark discharge and dielectric breakdown of the photoreceptor. Therefore, the squeezing effect of the insulating liquid is performed without opening the discharge potential. It is hoped that As a result of research on removing the insulating liquid from the holding member, it was found that corona discharge must be applied rapidly to achieve a high squeezing effect. In other words, even if the charging potential of the insulating liquid becomes high after applying a corona discharge, in other words, even if the charging is done strongly, if the charging is done gradually over a wide range, the squeezing effect of the liquid will be extremely weak. be. On the other hand, even if the discharge potential is low, if corona discharge occurs rapidly in a narrow range, the throttling effect becomes very large. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic copying apparatus which is improved so as to more efficiently aperture remove excess insulating liquid adhered to the surface of a photoreceptor by corona discharge without increasing the charging potential. An object of the present invention is to provide an insulating liquid removal device.

First, a conventional insulating liquid removal device will be explained with reference to FIG. 1. In the figure, 1 is a corona discharge electrode, 2 is a grounded shield member having a discharge opening, and 3 is a grounded shield member disposed in the discharge opening of the shield member. This is a corona discharge convergence member.

A high voltage is applied to the discharge line 1 by a power cord.
Reference numeral 4 denotes a holding member for the photoreceptor, transfer material, photosensitive sheet, etc., which moves in the direction of the arrow.

Reference numeral 5 denotes an insulating liquid such as a developer, and the discharge opening of the insulating liquid removing device is arranged to face the holding member.

In this insulating liquid removal device, an insulating convergence member 3
Therefore, the discharge width from the corona discharge electrode onto the holding member is narrowly limited. The insulating liquid 5 on the holding member 4 is charged by this corona discharge, and charges of the same polarity are repelled from each other by this charging, or the liquid is depressed and squeezed out by the electric field of the charges charged in the insulating liquid. It seems likely that

However, even with this insulating convergence member, the corona discharge may blur while reaching the holding member 4 from the convergence member 3.
Spreading occurred, and the corona discharge was not sufficiently converged by the converging member, and the liquid squeezing effect by the corona could not be sufficiently exerted.

Furthermore, if the width w of the opening of the corona convergence member of the corona discharger is narrowed, the charging effect will be weakened and a sufficient throttling effect will not be obtained. The effectiveness of the focusing member is weakened.

The present invention minimizes the attenuation of the charging effect when the opening is relatively narrow in a corona discharger in which an insulating corona convergence member is provided in the opening, and the boundary between the charged part and the non-charged part is The corona discharge is sharpened and an electric field is formed between the holding member and the convergence member to prevent blurring and spreading of the corona discharge, and the corona discharge to the holding member has a sharp potential gradient to effectively perform the liquid squeezing effect by the corona. be. The insulating liquid removing device of the present invention will be specifically described below with reference to the drawings. In order to improve the removal effect of the insulating liquid removal device, we conducted an improvement experiment and found that the aperture effect was greatly influenced by the "thickness" and "shape" of the insulating corona discharge focusing member.

I Regarding the thickness of the corona discharge convergence member In the device configured as shown in FIG. However, if the thickness of the corona discharge convergence member 3 is too thick, its tip will be strongly charged, which will strongly repel the corona discharge, making it difficult for it to pass through the corona discharge opening 6, resulting in less charge. .

This influence can be reduced by reducing the thickness of the corona discharge focusing member 3, thereby making it possible to concentrate a large amount of corona discharge on the holding member. Next, we will show this experimental data and clarify the numerical meaning of the thickness of the corona discharge focusing member, which affects corona discharge. The experiment was conducted using the configuration shown in FIG. FIG. 2a shows the thickness of the first corona discharge convergence member 31 provided on the entry side of the holding member with respect to the bottom of the corona discharge opening is d1, and the thickness of the second corona discharge convergence member 32 provided on the exit side of the opening. Assuming that the thickness was D2, the following results were obtained regarding the squeezing removal effect of the insulating liquid depending on the difference in thickness between the two.

Experimental conditions> Applied voltage to corona discharge wire 1 +8K Moving speed of holding member 4 300 mu/Sec Opening width (w) between corona discharge convergence members 31 and 32 5 mm Insulating liquid 5 Isopa-H (manufactured by Etsuso) Holding member Aperture effect of photosensitive drum with Se-Te layer and insulating layer provided on aluminum substrate The amount of insulating liquid remaining on the surface of the holding member is measured by the transfer content (Gr/A4 size transfer paper) on A4 size transfer paper.

Experimental results> Figure 2b shows the thickness of the main body of the first corona discharge convergence member 31 as d.
1. The thickness of the discharge opening tip is D3, and the thickness of the second corona discharge convergence member 32 is D2. The following results were obtained.

Experimental conditions> Applied voltage to corona discharge wire 1 +8κV Moving speed of holding member 4 300 pilgrims/Sec Opening width (w) between corona discharge convergence members 31 and 32 5W! L insulating liquid 5 Isopa H (manufactured by Etsuso) Holding member Photosensitive drum with Se-Te layer insulating layer provided on aluminum substrate Squeezing effect The amount of insulating liquid remaining on the surface of the holding member is transferred to A4 size transfer paper See the transfer content (Gr/A4 size transfer paper).

<Experimental Results> The experimental data above shows representative values, and the following facts were found as a result of this experiment.

By setting the thickness of the first corona discharge converging member 31 to about 2/3 or less of the opening width ω between the first and second corona converging members 31 and 32, a good aperture removal effect can be obtained.
Even if the main body of the corona discharge converging member 31 is thick, as long as its tip is thin, a sufficient constriction effect can be obtained. This figure shows an example of an insulating liquid removal device improved from the experiments shown in FIG. 3 and FIG. 2.

FIG. 3a shows the first and second corona discharge convergence members 3, 32.
FIG. 3b shows an example in which the shape of the discharge opening becomes gradually thinner toward the discharge opening, and FIG. 3b shows an example in which thin members 71 and 72 are provided at the tip forming the discharge opening. Note that when using a conductive material that is completely insulated from other materials or a conductive material that is grounded through a resistor instead of an insulating material as the material of the corona discharge convergence member 3, the same effect can be obtained by reducing the thickness of the member. A good aperture effect could be obtained. Regarding the shape of the corona discharge convergence members, it is considered that among the charges attached to the surfaces of the corona discharge convergence members 31 and 32, it is almost only the tip portions that affect the corona ions passing through the opening ω.

From this, we conducted an experiment to investigate the influence of the shape of the tip and found that if the tip has a gently curved surface, the influence of the charge attached to its surface will extend to corona ions that are relatively far away. However, the influence changes smoothly from near the tip to relatively far away.
Therefore, it is considered that the density of corona ions passing through the opening gradually increases from the periphery to the center of the opening. On the other hand, if a sharp corner exists at the leading edge of the corona discharge focusing members 31, 32, the influence of the charges attached to the surface on the corona ions will be strong in the vicinity of the corner, as in the case described above. However, the corona discharge convergence member 31
, 32, the total amount of charge attached to that point is relatively small, and the influence of the charge on the corona ions does not extend far. Therefore, the density of the corona ions passing through the opening is small at the very periphery, but relatively large at the slightly central part, and the boundary between the charged and non-charged parts of the holding member 4 is sharpened and photosensitive. layer 3
The effect of squeezing the upper insulating liquid can be strengthened. Next, we will show experimental data on how the shape of the opening tip of the corona discharge focusing member 3 affects the insulating liquid squeezing effect.

In the experiment, the first corona discharge convergence member 31 shown in FIG.
As shown in b, c, and d, the shape of the tip of the first corona discharge convergence member with a thickness of 3 mm is (a) radius of curvature 30b) radius of curvature 11
11L. (C) Right-angled cross section, (d) 45 mm cross section, and 1.5 mm thickness was used as the second corona discharge convergence member.

Experimental conditions> Voltage applied to the corona discharge wire 1 +8κ Moving speed of the holding member 4 300 m1/Sec Opening width (ω) between the corona discharge convergence members 31 and 32 5 mm Insulating liquid 5 Isopa-H (manufactured by Etsuo Corporation) held Member 4 Photosensitive drum aperture effect with Se-Te layer insulation layer provided on aluminum substrate
The amount of insulating liquid remaining on the surface of the holding member is determined by the transfer content to A4 size transfer paper (Gr/A4 size transfer paper).

As is clear from the above experiment Zeta 1, even if the corona discharge focusing member is flat, a sufficient effect can be obtained as long as there is a corner at its upper or lower end.

The sharper the corner of the leading edge is, the better, and the effect is particularly obvious when the radius of curvature of the leading edge is smaller than 1/2 of the thickness of the member. A similar effect can be obtained when a conductive material insulated from other materials is used instead of an insulating material as the corona discharge focusing member.

In the above experiment, when the second corona discharge convergence member was also provided with a corner at its tip, the constriction effect was increased.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing a conventional insulating liquid removal device;
FIGS. 2 to 4 are configuration explanatory diagrams showing an embodiment of the insulating liquid removing device of the present invention. In the figure, 1 is a corona discharge electrode, 2 is a shield member,
31 and 32 are focusing members, 4 is a holding member, and 5 is an insulating liquid.

Claims (1)

[Scope of Claims] 1. A corona discharge electrode, a shield member surrounding the corona discharge electrode and electrically insulated therefrom, and having a discharge opening;
a first corona convergence member provided near the discharge opening of the shield member on the entry side of the holding member with respect to the bottom of the discharge opening;
a second corona convergence member provided on the exit side, and the thickness of at least the tip of the first corona discharge convergence member is equal to 2 of the opening width between the first corona discharge convergence member and the second corona discharge convergence member.
An insulating liquid removal device characterized in that the temperature is /3 or less. 2. a corona discharge electrode, a shield member surrounding the corona discharge electrode, electrically insulated from the corona discharge electrode, and having a discharge opening;
a first corona convergence member provided near the discharge opening of the shield member on the entry side of the holding member with respect to the bottom of the discharge opening;
a second corona convergence member provided on the exit side, and the radius of curvature of the leading edge of at least one of the corona convergence members is smaller than 1/2 of the thickness of the convergence member. Sexual fluid removal device.