JPH07225516A - Excess developer removing device - Google Patents

Abstract

PURPOSE:To provide an excess developer removing device capable of imparting rigidity to a roll to suck the excess developer on an image carrying member, efficiently and selectively removing a carrier liquid from the developer sticking onto this image carrying member and affording good image quality free from transfer defects and unequalness. CONSTITUTION:This excess developer removing device removes the excess developer sticking onto the image carrying member formed with an electrostatic latent image after supplying the developer to the image carrying member and developing this image. The device described above has a liquid absorbent roll member 10 consisting of a perforated body which comes into contact with the surface of the image carrying member. This liquid absorbent roll member 10 consisting of the perforated body is composed of a sleeve 101 consisting of the perforated body having air permeability, electrical conductivity and rigidity and a perforated body layer 102 which is clad on this sleeve 101 consisting of the perforated body and has the electrical conductivity and elasticity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet electrophotographic copying machine which visualizes an electrostatic latent image with a liquid developer composed of toner particles dispersed in an insulating carrier liquid. The present invention relates to a surplus developer removing device used for an image recording device such as a printer and removing an excess developer adhering to an image carrier.

[0002]

2. Description of the Related Art Conventionally, in the above wet type electrophotographic copying apparatus, an electrostatic latent image formed on the surface of an image bearing member such as a photosensitive drum is visualized by a wet type developing apparatus. Has become. In this wet type developing device, a liquid developer composed of toner particles dispersed in an insulating carrier liquid is brought into contact with a photoconductor on which an electrostatic latent image is formed, and the toner particles in the liquid developer are electrostatically charged. It is configured to be attached to a latent image to form a visible image, and toner particles having a smaller particle size can be used as compared with a dry-type developing device, and high-quality development is possible. It has, and has recently received a lot of attention.

By the way, in the case of an image forming apparatus such as an electrophotographic copying apparatus using the above-mentioned wet type developing apparatus, in order to prevent bleeding of the toner image formed on the surface of the image carrier, the image carrier is prevented. The excess developer removing device for removing the excess developer adhering to the surface of is used. The excess developer may be removed by pressing a roller against the surface of the image carrier to squeeze the excess developer adhering to the surface of the image carrier, or by blowing an air stream onto the image carrier. There are known an air knife system that removes excess developer by applying the wind pressure and a corona squeeze system that utilizes corona discharge.

However, the above conventional method has the following problems. That is, in the case of the roller method, the developer adsorbed by the roller remains inside the roller, and if it dries in this state, it sticks to the roller as dirt, and uneven liquid removal or transfer of dirt at the next use. However, there is a problem in that Further, in the case of the air knife method, an air flow is blown to the surface of the image carrier to remove excess developer by the wind pressure, so that the air in the apparatus is a carrier liquid composed of an organic solvent or the like. In addition to being contaminated with toner that is fine particles and fine particles, a large amount of droplets of the developing solution are generated on the image surface, noise is generated, and the toner flows on the photoconductor due to wind pressure, so-called image flow easily occurs, and it is uniform. There is a problem that it is difficult to blow air onto the surface and the excess developer cannot be removed uniformly. Further, in the case of the corona squeeze method, ozone that causes deterioration of the toner and the photoconductor is generated by corona discharge, and when performing copying at a high speed, the liquid removal performance is low, which is disadvantageous. Have

Therefore, as a technique for solving these problems, Japanese Patent Application Laid-Open Nos. 3-80274 and 3-14 are available.
There are those disclosed in Japanese Patent No. 5680 and Japanese Patent Laid-Open No. 55-153971. JP-A-3-8027
The surplus developer removing device disclosed in Japanese Patent No. 4 is a surplus developer for removing the surplus developer on the photoconductor by a sponge roller provided inside the wet developing device and rotatably facing the photoconductor. In the removing device, the sponge roller has a hollow structure capable of sucking the developer from the inside thereof, and a negative pressure is applied to the hollow portion of the sponge roller to suck the developer penetrating into the sponge. The suction means and a roller cover for covering unnecessary portions of the roller are provided.

Further, in the case of the carrier recovery method of the developing solution disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-145680, after the latent image on the rotating latent image carrier is developed with the developing solution, this image surface is A cylindrical air-permeable foam roller having a layer of fine particles having a uniform particle size is brought into contact with the surface of the carrier, and the carrier of the excess developer on the holder is sucked and recovered from the inner cavity of the roller.

Further, in the case of the developing solution removing method for removing the excessive developing solution disclosed in the above-mentioned Japanese Patent Laid-Open No. 55-153971, development is carried out by a liquid developer consisting of an insulating liquid in which charged toner particles are dispersed. In a developer removing method of removing excess developer from the photoconductive surface containing the electrostatic image formed,
(A) A compressive polyurethane roller having a Shore A hardness of 45 ° or more and a resistivity of 10 ⁹ ohm-cm or less is brought into contact with the photoconductive surface, and (b) of the charged toner particles in the developer. An electric potential of a polarity corresponding to the polarity of the charge is applied to said roller such that (c) the roller has substantially zero relative motion between its surface and the surface of the photoconductor containing the electrostatic image of liquid development. It is configured to remove excess liquid from the surface of the photoconductor containing the developed electrostatic image by rotating so that

[0008]

However, the above-mentioned prior art has the following problems. That is, in the case of the excess developer removing device disclosed in the above-mentioned JP-A-3-80274, the sponge roller has a hollow structure capable of sucking the developer from the inside thereof, and the hollow sponge roller is hollow. The sponge roller comprises a suction means for applying a negative pressure to the portion to suck the developer penetrating into the sponge, and a roller cover for covering unnecessary portions of the roller. Is a single-layer sponge body that has no mechanical strength and it is virtually impossible to make uniform contact with the surface of an image carrier such as a photoconductor drum along its length. It has a problem that Further, in the case of the above-mentioned excess developer removing device, since the sponge roller is simply used while being hollow, a voltage having the same polarity as the charging polarity of the toner can be applied to this sponge roller. However, there is also a possibility that the toner may be adsorbed at the same time, which causes a problem that the toner density is lowered.

Further, in the case of the carrier recovery method of the developing solution disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-145680, polyurethane having a layer of fine particles of resin, metal, glass or the like having a uniform particle size on the surface thereof. Although a cylindrical breathable foam roller made of silicone rubber or the like is used, this cylindrical breathable foam roller also does not have rigidity as a roll body, and it is difficult to obtain cylindricity and practical strength is obtained. In addition to the above, there is a problem in that the voltage necessary for selectively removing the carrier liquid from the developed image cannot be applied.

Furthermore, in the case of the developing solution removing method for removing the excess developing solution disclosed in the above-mentioned JP-A-55-153971, the compressive polyurethane roller having a certain hardness is used as the roller. , The roller itself has a certain degree of rigidity and is practical in this respect, but since the roller is made of a compressible polyurethane roller,
When the roller absorbs the developer to some extent, it is difficult to absorb the developer any more. Even if the developer absorbed by the roller is removed by mechanical means, There is a problem that it is difficult to sufficiently increase the liquid removal efficiency.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art. The purpose of the present invention is to impart rigidity to a roll for sucking excess developer on the image carrier. Of course, it is possible to remove the carrier liquid selectively and efficiently from the developer adhered on the image carrier, and it is possible to obtain good image quality without transfer defects or unevenness. An object of the present invention is to provide a possible excess developer removing device.

[0012]

According to a first aspect of the present invention, there is provided an apparatus for removing excess developer, which comprises supplying a developing solution to an image bearing member on which an electrostatic latent image is formed, developing the image bearing member, and then developing the image bearing member. A surplus developer removing device for removing surplus developer adhering to the body, comprising a porous liquid absorbent roll member in contact with the surface of the image bearing member, which can be aerated. It is composed of a conductive and rigid porous sleeve and a conductive and elastic porous layer coated on the porous sleeve.

According to the second aspect of the present invention, the excess developing solution removing apparatus supplies the developing solution to the image bearing member on which the electrostatic latent image is formed, develops the image bearing member, and then adheres onto the image bearing member. A surplus developer removing device for removing the surplus developer, comprising a porous liquid absorbing roll member in contact with the surface of the image carrier,
The porous liquid absorbing roll member is composed of a porous sleeve having gas permeability, conductivity and rigidity, and a conductive and elastic porous layer coated on the porous sleeve. In this case, a foam made of conductive polyurethane made by a wet method is used.

The porous liquid absorbing roll member is provided with a suction means for sucking the excess developing liquid absorbed by the porous liquid absorbing roll member, if necessary.

Further, for example, a bias voltage is applied to at least one of the breathable, conductive and rigid porous body layer and the conductive and rigid porous body layer.

Further, as the above-mentioned breathable, conductive and rigid porous sleeve, for example, a mesh-shaped metal sponge sheet made of Ni-Cr is wound and formed into a sleeve shape.

Further, as the constitution of the porous liquid absorbing roll member, for example, the pore diameter is set so that the porous sleeve is larger than the porous layer.

By the way, the material of the porous sleeve which is permeable, electrically conductive and rigid is selected from, for example, sintered plastic, sintered ceramics or porous metal. Here, the above-mentioned sintered plastic is selected from, for example, ultra-high molecular weight polyethylene, polypropylene, fluororesin and the like. The sintered ceramics are selected from alumina, zirconia, silicon carbide and the like. Further, when the material forming the porous sleeve is insulative, as a method for making the outer surface of the porous sleeve conductive, for example, carbon, metal powder or the like is added internally, or metal deposition, The one selected from methods such as printing is used. Further, as the porous metal, for example, a sintered metal selected from stainless steel, brass, etc., or a reticulated metal sponge body selected from Ni, Ni-Cr (for example, "Celmet" product name of Sumitomo Electric Industries, Ltd.), or It is selected from a metal material having a hole mechanically or chemically provided in the thickness direction.

As the material for forming the conductive and elastic porous material layer, for example, a material selected from foamed materials such as conductive polyurethane and conductive fluororubber is used.

Further, as the suction means, for example, a means for sucking from the inside of the breathable porous sleeve or from the outer surface of the breathable porous sleeve or the conductive elastic porous body is used.

[0021]

In the apparatus for removing excess developer according to the first aspect of the present invention, the porous liquid absorbing roll member is covered with a porous sleeve having gas permeability, conductivity and rigidity, and the porous sleeve. Since the porous liquid absorbent roll member is provided with a porous sleeve that is breathable and has conductivity and rigidity on the inner peripheral side thereof, the porous body Since the liquid absorbing roll member has rigidity and can be brought into contact with the image carrier in a reliable and stable state, it can withstand practical use sufficiently and has dimensional stability during manufacturing. Further, since both the porous sleeve and the porous layer constituting the porous liquid absorbing roll member have conductivity, only a carrier liquid is selectively removed by applying a bias voltage to at least one of them. It is possible to perform high-quality image formation. Furthermore, since the porous sleeve has a porous layer having elasticity on its surface, the porous layer can efficiently absorb the excess developer.

Further, in the excess developer removing device according to the second aspect of the present invention, the porous body layer provided on the surface of the porous liquid absorbing roll member is a foam made of conductive polyurethane produced by a wet method. In addition to the apparatus according to claim 1, the conductive polyurethane foam made by a wet process has continuous pores and the size of the pores can be arbitrarily controlled. It is possible to form a porous layer mainly having fine pores of 100 μm or less, and it is possible to more efficiently adsorb the excess original image liquid on the image carrier by the capillary force of the fine pores.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an embodiment of a color copying machine using a wet type developer to which the excess developing solution removing device according to the present invention is applied.

In FIG. 2, reference numeral 1 denotes a photoconductor drum as an image carrier, and the photoconductor drum 1 is rotationally driven in a direction of an arrow at a predetermined rotational speed by a driving means (not shown). The surface of the photosensitive drum 1 is
After being uniformly charged to a predetermined potential by the primary charger 2, the image of the original is scanned and exposed by the exposure optical system 3,
An image-like electrostatic latent image is formed on the surface of the photosensitive drum 1. The electrostatic latent image formed on the photoconductor drum 1 has four colors of yellow (Y), magenta (M), cyan (C), and black (K), which are sequentially arranged around the photoconductor drum 1. One of the wet type developing devices 6Y, 6M, 6C and 6K is used for selective development. The four developing devices 6Y, 6M, 6C and 6K have the same configuration. Here, the yellow developing device 6Y
As an example, the wet developing solution used in the wet developing apparatus 6 is contained in the developing solution supply box 9, and the developing solution is passed through the developer supply tube 7 by a supply pump (not shown) to develop the developing apparatus. 6 is supplied. The developing solution supplied to the developing device 6 flows on the upper surface of the developing electrode 4 while the photosensitive drum 1
Develop the electrostatic latent image formed above. Further, excess developer of the developer supplied to the surface of the photoconductor drum 1 is collected and removed by the metalling roller 5 which rotates in the same direction as the rotation direction of the photoconductor drum 1 in a non-contact state. It

After that, the developer attached to the photosensitive drum 1 is further removed of excess developer before transferring the toner image. The excess developer removing device 1 according to one embodiment of the present invention.
It is removed by 0 and adjusted to an appropriate amount.

On the other hand, the transfer sheet is conveyed by the sheet conveying device 19, electrostatically wound around the surface of the transfer roll 25 and guided to the transfer area, and the developed image of the first color is transferred by the transfer corotron 15 to the transfer sheet. Transcribed on. After that, latent image formation, development, and transfer for the second, third, and fourth colors are similarly performed, and four colors of cyan, magenta, yellow, and black are formed on the transfer sheet held on the transfer roll 25. The toner image is transferred. Then, the transfer sheet is peeled off from the transfer roll 25 by the peeling corotron 16 and conveyed to the fixing device 18 via the conveying belt 17 to be fixed to form a permanent image. On the other hand, the toner and the developer remaining on the photoconductor drum 1 are cleaned by the sponge duster bar 21 and the cleaning blade 20 and the residual charge is erased by the charge eliminating lamp 23 to prepare for the next image forming step. In the figure, 22 is a carrier liquid filter, 13 is a cleaning and recovery liquid tank, 14 is a pump, and 24 is a static eliminating corotron pair for static eliminating the transfer roll 25.

By the way, the apparatus for removing excess developer according to this embodiment is provided with a porous liquid absorbing roll member which comes into contact with the surface of the image bearing member, and the porous liquid absorbing roll member is breathable, conductive and The porous sleeve has rigidity, and the porous sleeve having conductivity and elasticity is coated on the porous sleeve. That is, as shown in FIG. 2, the excess developer removing device is composed of a liquid absorbing roll 10 as a porous liquid absorbing roll member, a vacuum tank 11 for storing a liquid, and a pump 12.

The liquid absorbing roll 10 has a hollow structure as shown in FIG. Reference numeral 101 denotes a porous porous sleeve having air permeability, and this porous sleeve is made of a material having solvent resistance, conductivity and rigidity. The conductivity of the porous sleeve 101 does not cause any problem as long as the resistivity is 10 ⁶ Ωcm or less. As a material for forming the porous sleeve 101, for example, metal is used. As a porous metal,
For example, sintered metal such as stainless steel or brass, or N
A candidate is a mesh metal sponge such as i, Ni—Cr (“Celmet”, a product name of Sumitomo Electric Industries, Ltd.), or one having mechanically punched holes on its surface. In addition,
It has been found that when a mesh metal sponge body is used as the porous sleeve 101, the mesh metal sponge sheet may be wound three times or more from the viewpoint of uniform thickness of the sleeve. Further, as the material of the mesh metal sponge body, Ni-Cr is more suitable and more suitable than Ni as shown in FIG. 3 from the viewpoint of compressive strength.

Further, 102 is a conductive and elastic porous material layer, and it is a known technique to impart conductivity to the porous material layer, and the resistivity of the porous material layer is 10
^It is selected to be in the range of ¹⁰ Ωcm or less, preferably 10 ⁶ to 10 ⁹ Ωcm. Further, the rubber hardness of the porous layer is preferably relatively soft from about 10 degrees to about 60 degrees. Examples of the conductive porous body that can be used for this purpose include sponge bodies such as conductive polyurethane and conductive fluororubber. As shown in FIGS. 4 and 5, those having small pore diameters and those having high pore density are available. It can be seen that the liquid absorption efficiency is high. However, from the viewpoint of liquid absorption efficiency,
The conductive polyurethane was good, and among the same polyurethane sponges, as shown in FIG. 4, the elution type conductive polyurethane sponge by the wet method showed a better liquid absorption efficiency than the gas foaming type. This is because the elution type conductive polyurethane produced by the wet method has a process of elution of unnecessary parts during manufacturing, which makes it possible to make the pore size extremely small, and at the time of elution, the pores are completely connected to each other. Since it becomes foamy, it seems to lead to high liquid absorption. At this time, what is important is that when the porous conductive porous body sleeve 101 and the conductive elastic porous body layer 102 are provided thereon, it has air permeability in the thickness direction and prevents excessive pressure loss. The pore diameter of the porous conductive porous body sleeve 101 is roughly 10 to 200 μm, preferably 30 to 150 μm, the thickness of the sleeve 101 is 0.5 to 5 mm or less, and the conductive elastic porous body The layer 102 has a pore size of 3 to 50 μm, preferably 3 to 30 μm, a hardness of 10 to 60 degrees, and a thickness of 5
It is preferable that it is formed in the range of 0 μm to 5 mm. When the hole diameter of the conductive porous body sleeve 101 is larger than that of the conductive elastic porous body layer 102, the air and carrier liquid have good air permeability.

The liquid-absorbing roll 10 thus constructed is
Although it may be in direct contact with the toner image on the photosensitive drum 1,
They may be used in close proximity to each other with a gap of 50 μm or less. When the liquid absorbing roll 10 is used in contact with the surface of the photosensitive drum 1, the liquid absorbing roll 10 is driven to rotate in accordance with the rotation of the photosensitive drum 1.
When the liquid absorbing roll 10 is arranged in a non-contact state with the surface of the photosensitive drum 1, the liquid absorbing roll 1
0 is driven to rotate at the same speed as the peripheral speed of the surface of the photosensitive drum 1 or at a speed slower or faster than the peripheral speed of the surface of the photosensitive drum 1 by a driving unit (not shown).

Further, as shown in FIG. 1, suction of air from the liquid absorbing roll 10 is performed by a vacuum pipe 103 connected to an end portion in the longitudinal direction of the roll 10,
The sucked liquid is collected in the vacuum tank 12 through the vacuum pipe 103.

In the above construction, in the case of the color copying machine to which the excess developing solution removing apparatus according to this embodiment is applied, the excess developing solution deposited on the photosensitive drum is removed as follows. It That is, in the color copying machine, as shown in FIG. 2, the electrostatic latent image formed on the photoconductor drum 1 includes yellow (Y), magenta (M), cyan (C), and black (K). Four wet developing devices 6Y, 6
It is selectively developed by any one of M, 6C and 6K. As shown in FIG. 2, the wet developing solution stored in the developing solution supply box 9 is supplied to the developing apparatus 6 through the developer supply tube 7 by a supply pump (not shown). The developing solution supplied to the developing device 6 develops the electrostatic latent image formed on the photosensitive drum 1 while flowing on the upper surface of the developing electrode 4. At that time, the developer supplied along the upper surface of the developing electrode 4 adheres to the surface of the photosensitive drum 1. Excess developer of the developer supplied to the surface of the photosensitive drum 1 is collected and removed by the metalling roller 5 which rotates in the same direction as the rotating direction of the photosensitive drum 1 in a non-contact state. However, at this point, the surplus developer is still attached to the surface of the photosensitive drum 1.

Excessive developer remaining on the surface of the photosensitive drum 1 is removed by the liquid absorbing roll 10 of the excess developer removing device.

By the way, in this embodiment, as shown in FIG. 1, the liquid absorbing roll 10 is provided with a porous sleeve 101 which is permeable to air and has conductivity and rigidity, and this porous sleeve 1.
No. 01 coated with a conductive and elastic porous material layer 1
02, the liquid-absorbing roll 10 has a porous sleeve 101 that is breathable, conductive, and has rigidity on the inner peripheral side thereof, so that the liquid-absorbing roll 10 has rigidity and the image carrier Since it can be surely and stably contacted with the steel plate, it can withstand practical use sufficiently and has dimensional stability during manufacturing. In addition, the porous sleeve 101 and the porous layer 10 constituting the liquid absorbing roll 10
Since No. 2 has conductivity, it is possible to selectively remove only the carrier liquid by applying a bias voltage to at least one side, and it is possible to form a high quality image. Furthermore, the porous sleeve 101 is
Since the porous body layer having elasticity is provided on the surface, the porous developer layer 102 can efficiently absorb the excess developer.

When a foam made of a conductive polyurethane made by a wet method is used as the porous body layer 102 provided on the surface of the liquid absorbing roll 10, a foam made of a conductive polyurethane made by the wet method is used. Is a continuous wrapping of pores, the size of the pores can be controlled arbitrarily, a porous body layer having fine pores can be formed, and the capillary force of the fine pores allows the image carrier to be formed on the image carrier. The surplus original image liquid can be more efficiently adsorbed.

Next, the present inventor prototyped a color copying machine using the liquid absorbing roll 10 as shown in FIG. 1 and conducted an experiment for confirming the developing solution removal efficiency.

This experimental example will be described below. Experimental Example 1 First, as the photoconductor drum 1, one using a selenium-based photoconductor was used. As a wet type developer for developing the electrostatic latent image formed on the photoconductor drum 1, the carrier liquid is Isopar L (trade name of Exxon Co.), the polarity is negative, and the toner concentration is 2 The electrostatic latent image was developed in one color by the developing device 6 shown in FIG. 2 using 0.5% developer. At that time, when the dark potential of the electrostatic latent image was +850 V, the background potential was +150 V, the potential of the developing electrode 4 was −50 V, and the metalling roll 5 was +250 V, a good developed image was obtained. The toner concentration in the solid portion of this developed image (ratio of toner in the developing solution) was measured as follows. 5c formed on the photosensitive drum 1
The solid portion of m × 5 cm solid was scraped with a rubber blade, the weight was measured, and the weight of only the toner after sucking and heating at 120 ° C. for about 2 hours was measured, and the toner concentration was calculated to be 15%. It was.

Next, the liquid absorbing roll 10 used in the excess developing solution removing device was manufactured as follows. First, as the porous porous body sleeve 101, a 1-mm thick Ni-
A mesh-like metal sponge body sheet made of Cr (for example, "
Celmet "trade name of Sumitomo Electric Industries, Ltd." was wound in three layers to form a porous sleeve 101 having a wall thickness of 2 mm, a length of 300 mm and an outer diameter of 20 mmφ, and the pore diameter of the porous sleeve 101 was about 100 μm. This porous sleeve 10
The dimensional stability of No. 1 at the time of manufacturing could be ± 0.02 as the wall thickness and ± 0.1 as the runout. Further, as shown in FIG. 1, on the porous sleeve 101, an elastic type porous polyurethane layer 102 having a resistivity of 10 ⁸ Ωcm and a rubber hardness of 15 degrees as an elution type conductive polyurethane foam of a wet method (pore diameter 30 μm) is provided. The liquid absorbing roll 10 was manufactured by laminating 1 mm, and the liquid absorbing roll 10 was arranged as shown in FIG. The liquid absorbing roll 10 has the photosensitive drum 1 at both ends.
The diameter of the tracking roller was adjusted so as to form a contact nip width of 1 mm by being held by a tracking roller (not shown) for contacting both ends of the roller and maintaining a constant distance. In addition, the entire tracking roller is insulated from the surroundings, and a negative bias voltage of -1500V with the same polarity as the toner is used as the bias voltage.
The liquid absorbing roll 10 was driven to rotate so that the liquid absorbing roll 10 was brought into contact with the photoconductor drum 1 and the relative speed was 0.
The vacuum pump 11 has a discharge capacity of 30 l / min, and the liquid is collected in the vacuum tank 12 on the way. The vacuum pump 11 draws a pressure of 400 mm
It was set to Hg.

Under these conditions, as shown in FIG. 2, the excess carrier liquid on the developed image was removed, and the toner concentration was measured under the same conditions, and it was 37%.
Furthermore, when the image was transferred to a transfer sheet under these conditions, an image with delicate copy quality, which was typical of a liquid development image, was obtained.

Comparative Example 1 In Comparative Example 1, an image was formed on the photosensitive drum 1 and transferred onto a transfer sheet under exactly the same conditions as in Experimental Example 1 except that the excess developer removing device was not used. A defective copy with a large amount of carrier liquid, in which so-called image deletion occurred, was obtained.

Experimental Example 2 In this Experimental Example 2, the structure of the excessive developing solution removing device was a liquid absorbing roll 10, and the same 1 mm thick Ni-C as in Experimental Example 1 was used.
A reticulated metal sponge body sheet made of r is wound in four layers this time, and the thickness is 2 mm, the length is 300 mm, and the outer diameter is 20 mm.
A porous sleeve 101 having a hole diameter of φ of about 30 μm was prepared. The dimensional stability during manufacturing could be ± 0.02 as the wall thickness and ± 0.1 as the runout. Further, the same conductive elastic body layer 102 as in Experimental Example 1 was formed on the upper layer of the porous sleeve 101. Using the liquid-absorbing roll 10 configured in this way, liquid was removed under the same conditions as in Example 1, and the toner concentration after liquid removal was measured to be 28%, which was also good when transferred to a transfer sheet. A copy quality image was obtained.

COMPARATIVE EXAMPLE 2 In this comparative example 2, the structure of the excess developer removing device is such that the liquid absorbing roll 10 is not a mesh metal sponge sheet made of Ni--Cr but a mesh metal made of Ni having a thickness of 1 mm. A sponge body sheet was wound in three layers to form a porous sleeve 101 having a wall thickness of 2 mm, a length of 300 mm and an outer diameter of 20 mmφ and a hole diameter of about 100 μm. This porous sleeve 1
In No. 01, the seam was inconspicuous, but the strength was weak, and it was dented during production as a roll.

Experimental Example 3 In this Experimental Example 3, the structure of the excessive developing solution removing device was set to a liquid absorbing roll 10 and a mesh metal sponge body sheet made of Ni—Cr having a thickness of 1 mm was used as in Experimental Example 1. Wrapped in triple layers, wall thickness 2mm, length 300mm, outer diameter 20mm
A porous sleeve 101 having a φ hole diameter of about 150 μm was prepared. The dimensional stability during manufacturing could be ± 0.02 as the wall thickness and ± 0.1 as the runout. Further, in the same manner as in Experimental Example 1, an eluate type conductive polyurethane foam of a wet process having a resistivity of 10 ⁸ Ωcm and a rubber hardness of 15 degrees is provided on the upper layer of the porous sleeve 101 (provided that the pore diameter is 10 μm).
This time, the conductive elastic body layer 102 was formed by laminating 0.5 mm). The liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after the removal was measured.
It was 9%, and the liquid could be absorbed very efficiently. Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 4 In this Experimental Example 4, as in the case of Experimental Example 1, a mesh-shaped metal sponge sheet of 1 mm thick was used as the liquid absorbing roll 101 in the construction of the excess developer removing device. Three
Wrapped heavily, wall thickness 2mm, length 300mm, outer diameter 20m
A porous sleeve 101 of mφ was created. However, the hole diameter of the porous sleeve 101 is about 3 unlike the experimental example 1.
It was 0 μm. Dimensional stability during manufacturing is ± ±
The deviation was 0.02, and the deviation was ± 0.1. Further, in the same manner as in Experimental Example 1 above the porous sleeve 101, an elution-type conductive polyurethane foam of a wet process having a resistivity of 10 ⁸ Ωcm and a rubber hardness of 15 degrees (however,
The conductive elastic body layer 102 was formed by laminating 0.5 mm (having a pore size of 80 μm). Then, using the liquid absorbing roll 10 configured in this way, the liquid was removed under exactly the same conditions as in Example 1, and the toner concentration after removal was measured,
25%, and when transferred to a transfer sheet,
As the image, the image of the last minute quality was obtained. Moreover, the way the liquid was sucked seemed not to be smooth.

Experimental Example 5 In this Experimental Example 5, the structure of the excess developing solution removing device was reversed in this case. That is, as in the case of Experimental Example 1, as the liquid absorbing roll 10, a mesh-like metal sponge body sheet made of Ni—Cr having a thickness of 1 mm was wound in three layers, and the thickness was 2 m.
m, length 300 mm, outer diameter 20 mmφ hole diameter about 80 μm
A porous sleeve 101 of was prepared. The dimensional stability during manufacturing could be ± 0.02 as the wall thickness and ± 0.1 as the runout. Further, as in Experimental Example 1, 1 mm of an elution type conductive polyurethane foam (pore size 30 μm) of wet process having a resistivity of 10 ⁸ Ωcm and a rubber hardness of 15 was laminated on the upper layer of the porous sleeve 101 to be conductive. The elastic layer 102 is formed. And Experimental example 1
The liquid was removed under exactly the same conditions as above, and the toner concentration after the removal was measured, and it was 34%. When the toner was transferred to the transfer sheet, a good quality image was obtained. Also, the way the liquid was sucked in was smooth.

Comparative Example 3 In this Comparative Example 3, the excess developer removing device was constructed such that the absorbing roller 10 was a double-layered metal mesh sponge body sheet made of Ni and having a thickness of 1.5 mm. A porous sleeve 101 having a hole diameter of about 100 μm having a diameter of 2 mm, a length of 300 mm and an outer diameter of 20 mmφ was prepared. This porous sleeve 1
In 01, the seams were not noticeable at first glance, but their presence was at a level where they could be seen. For dimensional stability, the seam is thick,
At first glance, it was judged to be unusable due to uneven thickness.

Experimental Example 6 In this Experimental Example 6, among the constitutions of the excess developer removing device,
As a porous porous sleeve 101, stainless steel S
Using a sintered metal material of US304 having a pore size of 100 μm,
A porous sleeve 101 having a wall thickness of 2 mm, a length of 300 mm and an outer diameter of 20 mmφ was prepared. Further, the same conductive elastic body layer 102 as in Experimental Example 1 was formed on the porous sleeve 101. The liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after removal was 37%. Even when the toner was transferred to a transfer sheet, an image with good copy quality was obtained.

Experimental Example 7 In Experimental Example 7, among the constitutions of the excess developer removing device,
As the porous porous sleeve 101, as shown in FIG. 6, a stainless steel SUS304 plate having a hole 142 diameter of 1 m is used.
The sleeve 141 was made of a material that was punched continuously with mφ and a pitch of 2 mm. The thickness of the porous sleeve 141 was 0.8 mm, the length was 300 mm, and the outer diameter was 20 mmφ, and the same conductive elastic body layer 102 as in Experimental Example 1 was formed on the upper layer. The liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after removal was measured and found to be 35%.
Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 8 In Experimental Example 8, among the constitutions of the excess developer removing device,
As the porous porous sleeve 101, a cylindrical ceramic sleeve 101 having a hole diameter of 50 μm, a thickness of 1 mm, a length of 300 mm and an outer diameter of 20 mmφ was prepared using alumina. Since the surface of the ceramic sleeve 101 is insulative, gold was melted and coated thinly with a vacuum deposition apparatus. It was good to check the continuity with a tester. Further, the same conductive elastic body layer as in Experimental Example 1 was formed on the porous sleeve 101. Then, the liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after the removal was measured and found to be 35%. Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 9 In Experimental Example 9, among the constitutions of the excess developer removing device,
20% by weight of aluminum powder as metal powder in ultra high molecular weight polyethylene as the porous porous sleeve 101
By mixing, a semiconductive porous sleeve 101 was created. The porous sleeve 101 has a thickness of 22 m and a length of 3
00 mm, outer diameter 20 mmφ, hole diameter 50 μm, and the same conductive elastic body layer 1 as in Experimental Example 1 on the sleeve 101.
02 was formed. In the image forming test, the liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after the liquid removal was measured and found to be 35%. Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 10 In Experimental Example 10, Experimental Example 1 was used as the porous porous sleeve 101 in the structure of the excess developer removing device.
The semiconductive foamed fluororubber foam 102 having a resistivity of 10 ⁹ Ωcm was formed on the mesh-shaped Sponge body sleeve 101 made of Ni-Cr and having a pore size of 100 μm used in 1. 20% by weight of carbon was mixed into Viton rubber (trade name of DuPont) having solvent resistance as fluororubber to form conductive foamed Viton rubber foam 102 of 0.3 mm.
When the surface was observed with a microscope, an open cell structure was confirmed. In the image forming test, the liquid was removed under exactly the same conditions as in Experimental Example 1, and the toner concentration after removal was 33%.
Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 11 In Experimental Example 11, Experimental Example 1 was used as the porous porous sleeve 101 in the structure of the excess developer removing device.
Also, the liquid absorption roll 10 used in Experimental Example 10 was used to perform a test by the suction method from the outer surface shown in FIGS. 7 and 8. In this experimental example, the vacuum pipe 114 was connected to the end of the suction roll 113 in the longitudinal direction, and the suction slit 1
15 was made to oppose the liquid absorption roll 10. Suction slit 11
The opening width of 5 was 3 mm, and this was brought into contact with the liquid suction roll 10. Then, the liquid absorption roll 10 was contacted with the photosensitive drum 1 just on the opposite side of the opening of the suction slit 115 to remove the liquid. An experiment was conducted under the same conditions as in Experimental Example 1 except that the vacuum system was sucked from the outer surface. When the toner concentration after removing the liquid was measured, it was 30% in both the liquid-absorbing rolls 10 used in Experimental Examples 1 and 10. Similarly, an image with good copy quality was obtained even when transferred to a transfer sheet.

Experimental Example 12 In Experimental Example 12, zirconia was used as the porous porous sleeve 101 in the structure of the excess developer removing device, as shown in FIG. 9, with a pore diameter of 50 μm and a thickness of 1 μm.
A cylindrical ceramic sleeve 101 having a size of mm, a length of 300 mm and an outer diameter of 20 mmφ was prepared. To impart conductivity to the surface of the porous sleeve 101, a semi-conductive surface was obtained by thin coating using a gold sputtering device. An image forming test and a liquid removing test by suction from the inside were conducted under the same conditions as in Experimental Example 1 using this porous sleeve 101 (without providing the elastic porous layer as the upper layer), and the toner concentration was 32. %, The copy quality on the transfer sheet was also good.

Experimental Example 13 In Experimental Example 13, as a porous porous sleeve 101 in the structure of the excess developer removing device, 20% by weight of aluminum powder as metal powder was mixed into polypropylene to make semi-conductive material having a pore diameter of 100 μm. The polymer sintered porous body sleeve 101 was formed. Using this porous sleeve 101 (without providing the upper layer), an image forming test and a liquid removal test by suction from the inside were conducted under the same conditions as in Experimental Example 12, and the toner concentration was 28% on the transfer sheet. The copy quality was also good.

Experimental Example 14 In Experimental Example 14, polytetrafluoroethylene particles were used as the porous porous sleeve 101 in the structure of the excess developer removing device, and the pore diameter was 30 μm and the thickness was 3 μm.
A cylindrical sintered plastic sleeve 101 having a diameter of 300 mm, a length of 300 mm, and an outer diameter of 20 mm was prepared. Using this porous sleeve 101 (without providing an upper layer and a conductive layer), a drawing test and a liquid removal test by suction from the inside were performed under the same conditions as in Experimental Example 12, and the toner concentration was 30%.
The copy quality on the transfer sheet was also good. In this case, it is considered that it is not the bias voltage that causes the carrier liquid to be extracted from the excess developer, but the fact that the surface of polytetrafluoroethylene is triboelectrically charged to the same polarity as the toner.

Experimental Example 15 In Experimental Example 15, silicon carbide was used as the porous porous sleeve 101 in the structure of the excess developer removing device, and the pore diameter was 50 μm, the thickness was 1 mm, and the length was 300 m.
m, outer diameter 20 mmφ, cylindrical ceramic sleeve 10
Created 1. To give conductivity to the surface of the porous sleeve 101, a semi-conductive surface was obtained by thin coating using a gold sputtering device. This porous sleeve 1
01 (without providing the upper layer) was tested by the suction method from the outer surface shown in FIG. The vacuum pipe 134 is connected to the suction roll 133, and the suction slit 13
5 was opposed to the sleeve 131. Suction slit 135
Had an opening width of 3 mm and was brought into contact with the liquid suction roll 10. Then, an image forming test and a liquid removal test by suction from the inside are performed under the same conditions as in Experimental Example 12 so that the liquid absorbing roll 10 is brought into contact with the photosensitive drum 1 on the side opposite to the opening of the suction slit 135. As a result, the toner concentration was 28%. When transferred to a transfer sheet in the same manner, an image with almost good copy quality was obtained.

[0058]

The present invention has the above-described structure and operation. In the excess developer removing device according to the first aspect of the present invention, the porous liquid absorbent roll member is permeable to air and is conductive. Moreover, since the porous sleeve having rigidity and the conductive and elastic porous layer coated on the porous sleeve are provided, the porous liquid absorbing roll member can be vented to the inner peripheral side thereof and electrically conductive. Since the porous liquid absorbing roll member has rigidity and is capable of contacting the image bearing member in a reliable and stable state, the porous liquid absorbing roll member can withstand practical use sufficiently. It is possible and has dimensional stability during manufacturing. Further, since both the porous sleeve and the porous layer constituting the porous liquid absorbing roll member have conductivity, only a carrier liquid is selectively removed by applying a bias voltage to at least one of them. It is possible to perform high-quality image formation. Furthermore, since the porous sleeve has a porous layer having elasticity on its surface, the porous layer can efficiently absorb the excess developer.

Further, in the excess developer removing device according to the second aspect of the present invention, as the porous body layer provided on the surface of the porous liquid absorbing roll member, a foam made of conductive polyurethane produced by a wet method is used. In addition to the apparatus according to claim 1, the conductive polyurethane foam made by a wet process has continuous pores and the size of the pores can be arbitrarily controlled. It is possible to form a porous layer having fine pores, and it is possible to more efficiently adsorb the excess original image liquid on the image carrier by the capillary force of the fine pores.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a porous liquid absorbent roll member showing an embodiment of an excess developer removing device according to the present invention.

FIG. 2 is a block diagram showing a color copying machine to which an embodiment of an excessive developing solution removing device according to the present invention is applied.

FIG. 3 is a graph showing the compressive strength of a sleeve.

FIG. 4 is a graph showing the relationship between the hole diameter of the sleeve and the suction efficiency.

FIG. 5 is a graph showing the relationship between the density of holes in the sleeve and the suction efficiency.

FIG. 6 is a schematic view showing a porous sleeve according to another embodiment.

FIG. 7 is a cross-sectional configuration diagram showing another embodiment of the porous liquid absorbent roll member.

FIG. 8 is an external perspective view showing a suction roll.

FIG. 9 is a cross-sectional configuration diagram showing a porous sleeve according to another embodiment.

FIG. 10 is a cross-sectional configuration diagram showing a porous sleeve according to still another embodiment.

[Explanation of symbols]

1 photoconductor drum (image carrier), 10 liquid absorbing roll, 1
01 porous sleeve, 102 conductive elastic layer, 10
3 Vacuum piping.

Claims (6)

[Claims] 1. A surplus developer removing device for removing a surplus developer adhering to an image bearing member after the developer is supplied to an image bearing member on which an electrostatic latent image is formed to develop the image bearing member. A porous liquid absorbing roll member that comes into contact with the surface of the image carrier is provided, and the porous liquid absorbing roll member is a breathable, conductive and rigid porous sleeve, and a conductive sleeve coated on the porous sleeve. A device for removing excess developer, which is characterized in that it is composed of a porous layer having elasticity and elasticity. 2. A surplus developer removing device for removing a surplus developer adhering to an image carrier after the developer is supplied to an image carrier on which an electrostatic latent image is formed to develop the image carrier. A porous liquid absorbing roll member that comes into contact with the surface of the image carrier is provided, and the porous liquid absorbing roll member is a breathable, conductive and rigid porous sleeve, and a conductive sleeve coated on the porous sleeve. And a porous layer having elasticity,
A device for removing excess developer, wherein a foam made of conductive polyurethane made by a wet method is used as the porous body layer. 3. The surplus developer removing device according to claim 1, further comprising suction means for sucking the surplus developer absorbed by the porous liquid absorbent roll member. 4. A bias voltage is applied to at least one of the porous sleeve having gas permeability, conductivity and rigidity and the porous layer having conductivity and rigidity. The excess developer removing device according to item 3. 5. The breathable, electrically conductive and rigid porous sleeve formed by winding a mesh metal sponge sheet made of Ni—Cr into a sleeve shape is used. The excess developer removing device according to any one of items 1 to 4. 6. The porous liquid absorbing roll member according to claim 1, wherein the porous sleeve has a larger pore size than the porous layer. Excess developer removing device.