JPS5911908B2 - Insulating liquid removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an insulating liquid that removes excess insulating liquid adhering to a transfer photoreceptor, transfer material, photosensitive sheet, etc. by using corona discharge in the copying process of various electrophotographs. Relating to a removal device.

More specifically, in the present invention, after an electrostatic latent image formed on the surface of a transfer photoreceptor is developed with a liquid, excess liquid developer adhering to the transfer photoreceptor before being transferred to a transfer material, or Excess liquid developer that adheres to the transfer material after transfer to the transfer material, or excess liquid developer that adheres to the surface of the photosensitive sheet after liquid developing the electrostatic latent image formed on the surface of the photosensitive sheet and before fixing. The present invention relates to an insulating liquid removal device for removing chemicals, etc.
In a transfer-type wet-type electrophotographic copying device, an electrostatic latent image on the surface of a photoconductor is generally developed with a liquid developer, and this developed image is transferred to a transfer material to fix the transferred image on the transfer material. After that, the residual developer remaining on the photoreceptor is cleaned by a cleaning device using a cleaning liquid, and the cleaned photoreceptor is reused.

In such a conventional electrophotographic process, the copied image on the transfer material has fogging even in bright areas of the original image, and also has image deletion, 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 the developer usually contains at least toner and carrier, so the inner image area of this toner This is thought to be due to the fact that floating toner is transferred as is, and toner attracted to the image area is also flowed out from the image area along with the carrier flow due to the pressure during transfer. On the other hand, the developer transferred onto the transfer material also has a considerable amount of excess carrier, and therefore, when dried in a drying device, a large amount of carrier gas is generated, which adversely affects the health and hygiene of copying operators. Therefore, conventionally, after development, a squeezing roller or the like is arranged on the photoreceptor to squeeze out the excess developer. However, even when this squeezing roller is used, image disturbances may occur as in the case of transfer, and even when a pressure squeezing roller is used to remove excess developer on the transfer material, similar image disturbances may occur. In addition, in electrofax type electrophotography, after the electrostatic latent image on the surface of a photosensitive sheet is developed with a liquid, image distortion occurs when the excess developer on the photosensitive sheet is removed using a pressure squeezing roller. If this is done, carrier gas will be generated due to this, and as mentioned above, it is extremely hygienic.

In order to solve the above-mentioned problems, an improved insulating liquid removal device applies a corona discharge to the insulating liquid excessively adhered to the surface of the image holding member in a wet type electrophotographic copying machine and squeezes and removes the excess liquid. has been proposed and implemented.

That is, by moving the corona discharger relative to the surface of the insulating liquid attached to the image holding member and charging one side to the other in order, the liquid surface is depressed and a squeezing effect is created, causing excess liquid to drain away. It is removed from the image bearing member.

The insulating liquid squeezed out as described above is then removed by liquid removal means such as suction or gravity.

The discharge polarity when the insulating liquid in the image holding member soil is squeezed and removed by corona discharge will be described.
First, if the target subject to the aperture action is a developer that has developed the electrostatic latent image on the surface of the photoreceptor, the charged polarity due to corona discharge is the same polarity as the charged polarity of the toner that has developed the electrostatic latent image on the surface of the photoreceptor. It is good that the This is because the developer is squeezed while the developer toner is pressed against the surface of the photoreceptor by the charge generated by the corona discharge, so the squeezing effect can be obtained without disturbing the image. However, when the electrostatic latent image strongly attracts the toner, liquid squeezing can be performed satisfactorily without disturbing the image in any way even if the charged polarity of the corona discharge for removing the developed image is opposite to that of the developed toner.
When squeezing and removing an insulating liquid such as a cleaning liquid, the corona discharge polarity can be selected completely freely. The above is a case where direct current is applied to the corona discharge electrode, but if the surface of the insulating liquid can be charged not only by applying an alternating current voltage, but also by applying an alternating current voltage, a sufficient aperture removal effect has been obtained in experiments, so corona discharge It is also possible to apply an alternating voltage to the electrodes. In order to more efficiently remove the insulating liquid on the holding member by corona discharge as described above, it is necessary to provide additional means to the ordinary corona discharger.

In order to increase the liquid squeezing force, it is possible to increase the voltage applied to the corona discharge electrode or to bring 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, it is desired to enhance the squeezing effect of the insulating liquid without increasing the discharge potential. It has been found that in order to obtain a high squeezing effect for removing the insulating liquid on the image holding member, it is necessary to rapidly apply a corona discharge to the liquid surface.

That is, even if the charged potential of the insulating liquid becomes high after the corona discharge is applied, the squeezing effect of the liquid is extremely weak when the charging is gradually carried out over a wide range.
On the other hand, even if the discharge potential is low, if corona discharge is rapidly performed in a narrow range on the liquid surface, the throttling effect becomes large. FIGS. 1A and 1B are explanatory diagrams of a conventional device that is capable of applying a corona discharge to a narrow range on the surface of an insulating liquid.

In the figure, 1 is a corona discharge electrode to which a high voltage is applied, 2
31 and 32 are a shield member which is grounded and surrounds the electrode 1 except for the discharge opening, and which is electrically insulated from the electrode 1; This is a corona discharge convergence member provided near the aperture and between the image holding member and the aperture.

The focusing members 31 and 32 are opposed to each other to form a corona discharge passage opening, and the members 31 and 32 are shown in FIG.
Even if it is arranged parallel to the image holding member as shown in FIG.
They may be arranged at an angle as shown in . In any case, it is either an insulating (dielectric) member or a conductive member such as metal, which is arranged on the entrance side and the exit side of the image holding member 4 with respect to the bottom of the discharge opening, and constitutes a corona discharge convergence means. If so, it is electrically insulated from the electrode 1, shield member 2, etc. Reference numeral 4 denotes an image holding member such as a photoreceptor, a transfer material, a photosensitive sheet, etc., which moves in the direction of the arrow.

5 is an insulating liquid such as a developer.

The discharge opening of the insulating liquid removal device is arranged toward the image holding member 4. In this insulating liquid removal device,
The convergence members 31 and 32 narrowly limit the discharge width from the corona discharge electrode to the liquid 5 of the image holding member soil. The insulating liquid 5 is charged by this corona discharge, and the charged charges of the same polarity repel each other, or the liquid is depressed by the electric field of the charges charged in the insulating injection liquid, whereby the liquid is squeezed and removed. be done. The present invention is shown in FIGS. 1A and B.
By adjusting the positions of the corona discharge convergence members 31 and 32 provided near the discharge opening of the shield member 2 shown in FIG. The charging potential of the insulating liquid 5 is suppressed to a low level, and the effect of squeezing and removing the insulating liquid 5 is further improved.

That is, an object of the present invention is to install an insulating member or an electrically shielding member near the discharge opening of a corona discharger when removing insulating liquid excessively attached to the surface of a photoreceptor in an electrophotographic copying apparatus by corona discharge. A corona discharge convergence member made of a conductive material insulated from other materials is arranged, and its position is adjusted so that corona discharge is rapidly applied to the liquid surface and the insulating liquid is squeezed out. An object of the present invention is to provide an improved insulating liquid removal device that improves its effectiveness under all circumstances.

That is, in the apparatuses shown in FIGS. 1A and 1B, the corona discharge convergence means provided at the opening of the corona discharger is located on the upper side of the perpendicular line drawn from the electrode 1 to the image holding member 4 with respect to the moving direction of the image holding member 4. As shown in the figure, a perpendicular line hanging from the corona discharge wire 1 onto the image holding member 4 and a first converging member 32 are provided on the lower side. When the distance to the convergence member 31 is b, and the distance between the perpendicular line and the second convergence member 32 is a, a=b in the apparatuses shown in FIGS. 1A and B, but according to the present invention, this distance A
, b to control the squeezing removal effect and charging potential of the insulating liquid.

Therefore, the following experiment was conducted by varying A and b to investigate the relationship between A and b and the liquid squeezing removal effect, and the results shown in FIGS. 2 to 5 were obtained.

The apparatus shown in FIG. 1 was set as follows by making b variable (that is, making the member 31 movable).

Corona discharge wire 1 and photosensitive wire 10m7! L ram 4
Distance between surfaces: Discharge opening of conductive shield plate 2: 23m
m mouth width corona discharge convergence plate 3, 32 and sense 2.51I
1 Light drum 4 surface distance I2'' Application to corona discharge wire 1 +8.0KV voltage Material of insulating liquid 5
Isopa-H (manufactured by Etsuso) Moving speed of photoreceptor 4 surface 3007!1m/Sec distance a
・・・・・・・・・・・・3.57n71L
Distance b ・・・・・・・・・・・・
Variable corona discharge convergence members 31, 32...
... Due to changes in the insulating member and the distance b, the photosensitive drum 4
FIG. 2 is a graph showing data regarding the amount of insulating liquid remaining on the surface transferred to A4 size transfer paper (Gr/A4 size transfer paper?).

In the graph, the horizontal axis shows the distance b (Mm) and the vertical axis shows the insulating liquid content of the transfer paper (Gr/A4 size transfer paper piece. According to this, the most efficient aperture removal is achieved when the value of b is 1.5 mm) It can be seen that a relatively efficient aperture removal effect can be obtained in the range of 0.3m7!L to 3.0u.Figure 3 shows that the distance b was fixed at 1.5mm using the above-mentioned experimental apparatus. , is a graph showing the results obtained when the distance a is made variable (that is, the member 32 is made movable), and is shown on the vertical axis of the a graph.

The vertical axis is the same as in FIG. According to this, the distance a is 4
The aperture removal effect is greatest when the diameter is 2mm to 5.5m.
In the range of m, the aperture removal effect is relatively efficient and good.

Next, the apparatus shown in FIG. 1 was set up as follows.

Distance between corona discharge wire 1 and surface of photosensitive drum 4 Distance for discharge of conductive shield plate 2 23 m 1 L
Mouth width Distance between the corona discharge convergence plates 31, 32 and the surface of the photosensitive drum 4 Voltage applied to the corona discharge wire 1 0.6 mm +8.0 KV Material of the insulating liquid 5 Isopa-H (manufactured by Etsuso) Surface of the photosensitive drum 4 Movement speed of 3001! l/
Sec distance a...!・・・・・・
...3.57Itm distance b...
...... Variable corona discharge convergence member 31, 3
2......Insulating member Figure 4 shows distance b (Mm) on the horizontal axis and insulating liquid content (Gr/A) on the vertical axis.
4 is a graph of experimental results showing the charging potential (V) charged on the surface of the photosensitive drum at this time.

According to the solid line 1 in the graph, the liquid squeezing effect is b
A range of 0.5 mm to 3.0 mm is relatively efficient, and in order to obtain the effect within this range, the distance from 0.5 mm to 1.0 m, which minimizes charging of the photosensitive drum surface from the broken line 2 of the graph 71! It can be said that the range of is convenient in practice.

Figure 5 shows that the distance b is 1.57! using the above-mentioned experimental apparatus. This is a graph showing experimental results obtained by fixing Lm and varying the distance a, with a as the horizontal axis and the vertical axis as in FIG. 4.

According to solid line 1, the aperture removal effect is greatest when the distance a is 3.5m1L, which is 2.57! T7! In the range of L to 4.5 mm, the aperture removal effect is relatively efficient and good.

Further, according to the broken line 2, it can be seen that the smaller the distance a, especially when it is 3 mm or less, the less the photosensitive drum surface tends to be charged. As described above, based on the experimental data shown in FIGS. 2 to 5, we will comprehensively examine the liquid squeezing removal effect and the effect of lowering the charging voltage on the photosensitive drum surface by changing the distances a and b.

Squeezing removal effect> If both the distances A and b are too large or too small, the squeezing effect will deteriorate.

There is also an optimum value for the aperture effect, as shown in Figures 2 and 3.
As can be seen from the comparison between Figures 4 and 5, changes in distance b have a fairly large effect on the aperture effect, but distance a
A change in does not have a large effect on the aperture effect. This is thought to be due to the fact that by adjusting the b value, a sharp charging gradient was created on the liquid surface by blocking the vicinity of the central part where the charging intensity where the corona discharge current was highest was blocked by the focusing member. <Charged voltage on the surface of the photosensitive drum> The surface potential of the photosensitive plate increases as the distances A and b become larger. Large quantities are more expensive;
It is more effective to control the surface potential of the photosensitive plate by adjusting the a value.

This a value needs to be within a range that does not weaken the charging strength in the central portion, but if it exceeds that value, it will have little effect on developer squeeze removal, and the main function will be simply to increase the amount of charging.

As a result of the above experiments, it is more effective to adjust the aperture removal amount of the developer by adjusting the b value, and to adjust the potential on the surface of the photoreceptor by adjusting the a value.

In particular, as shown in Figure 6, the range of a value and b value is 1 and a/b≦
It is preferably 20, more preferably 1.5 a
/b<4.5 was found to be ideal. In addition, in the above experiment, the same effect was obtained by using a conductive member completely insulated from others as the focusing member instead of the insulating member.

FIG. 7 shows that 32 of the corona discharge convergence members 3, 32 are placed outside the opening width of the shield 2, or are removed, and the direction of travel of the photoreceptor 4 is set from a perpendicular line drawn from the electrode 1 to the photoreceptor 4. This shows a case in which only the upper portion 31 is left; in this configuration, the charging voltage on the photoreceptor surface is somewhat higher, but the developer can be removed efficiently. In the case of Figure 7. The b value is defined as explained in FIG. 1 etc., but the a value is determined by the vertical line drawn from the electrode 1 to the image holding member 4 and the movement of the image holding member 4 of the discharge opening formed by the shield member 2, as shown in the figure. Regarding the direction, it is defined as the distance between the end on the lower side of the perpendicular line. And A
It goes without saying that the same thing can be said about the ratio of ,b as mentioned above. As detailed above, by adjusting the a value and/or b value, it is possible to adjust the aperture strength for the insulating liquid and the charging potential for the photoreceptor surface, so by making these variable, the insulating liquid It is possible to control the amount of aperture removal. For example, in a wet-type electrophotographic copying machine, when an electrostatic latent image on a photoreceptor is squeezed out after liquid development and before transfer, excess developer is squeezed out. It is necessary to adjust a and/or b by moving and adjusting , and adjust the aperture strength as described below.

When the speed of the photoreceptor drum is variable...
・Changing the transfer paper so that the faster the aperture, the stronger the aperture.
・・・・・・Changes in the temperature of the developing solution, which causes more forceful squeezing for materials with poorer oil absorption.・・・・・・・・・ Changes in the image, which causes more forceful squeezing to occur at lower temperatures. ...A stronger aperture is applied to a line image than a solid black image.As described in detail above, according to the present invention, by adjusting the movement of the convergence members 31 and 32, a liquid aperture effect can be achieved depending on the situation. This is extremely effective because it can lower the charging potential of the holding member as much as possible and improve the aperture removal effect.

[Brief explanation of the drawing]

FIGS. 1A and 1B are explanatory diagrams of the configuration of a conventional insulating liquid squeezing device, FIGS. 2 to 5 are graphs showing changes in the squeezing removal effect due to movement of the corona discharge convergence member, and FIGS. 6 and 7 The figure is an embodiment diagram of the present invention.

Claims (1)

[Scope of Claims] 1. An insulator comprising a corona discharge electrode, a shield member surrounding and electrically insulating from the corona discharge electrode, and having a discharge opening, and attached to an image holding member moving in a predetermined direction. In an insulating liquid removal device that removes excess liquid by applying a corona discharge to the liquid, a corona discharge electrode is located near the discharge opening of the shield member and in the direction of movement of the image holding member. A movable corona discharge convergence member is provided at a position above the perpendicular line drawn to the image holding member, and the distance between the perpendicular line and the convergence member is adjusted by moving the convergence member. An insulating liquid removal device featuring: 2. a corona discharge electrode, a shield member that surrounds and is electrically insulated from the corona discharge electrode and has a discharge opening;
In an insulating liquid removal device that applies a corona discharge to the insulating liquid adhering to an image holding member moving in a predetermined direction and removes excess liquid, a position near the discharge opening of the shield member is provided. It has a movable corona discharge convergence member disposed at a position on the lower side of a perpendicular line drawn from the corona discharge electrode to the image retention member with respect to the traveling direction of the image retention member, and the movable corona discharge convergence member is moved to An insulating liquid removing device characterized in that the distance between a perpendicular line and the convergence member is adjusted.