JPH05346692A - Wet type developing method and its device - Google Patents

Abstract

PURPOSE:To provide the two-component wet type developing method which prevents the consumption of a developer by adhesion to the non-image part of an electrostatic latent image and can stably form the high-resolving power image substantially free from surface staining at a high density over a long period of time. CONSTITUTION:The developer which is a dielectric substance induces dielectric polarization and is attracted to the image part of the electrostatic latent image and the liquid surface builds up (b, c) when the two-component developer is held on the surface of a conductive developing roller 131 and is opposed to the electrostatic latent image on a photosensitive drum 10 (a). The toner in the liquid carrier migrates to the surface layer of the developer at this time (c). The built-up developer part sticks selectively to the charge part of the electrostatic latent image to form the state of bridging between only the charge part of the electrostatic latent image and the developing roller 131. The electrophoresis of the charged toner which is the ordinary two-component developer is executed in the developer in this bridging state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet developing method and its apparatus used in image forming apparatuses such as copiers, facsimiles and printers, and more particularly to a wet developing method and apparatus using a two-component developer. is there.

[0002]

2. Description of the Related Art Conventionally, dry developing methods and wet developing methods are known as the developing methods adopted for image formation. As a wet developing method, for example, a developer obtained by dispersing a toner made of carbon black coated with a resin in a carrier liquid made of a petroleum solvent such as Isopar (trade name) is used as a latent image on which an electrostatic latent image is formed. The developing solution is brought into contact with the surface of the latent image carrier by supplying it between the surface of the carrier and a counter electrode arranged at a constant interval on the surface, and the electrophoretic phenomenon of the toner charged in the carrier liquid is utilized. Generally, a method of developing an electrostatic latent image is developed. This developer is called a two-component developer because a carrier liquid is used for charging the toner and transferring the toner. The developing method using this two-component developing solution has an advantage that high resolution can be obtained because the toner particles are finer than the toner in the general dry developing method.

However, in the wet developing method using a two-component developing solution, the developing solution is a portion of the electrostatic latent image to which the toner should be attached (hereinafter referred to as an image portion. The part that should not be called is called non-image part.)
Not only does it contact the non-image part of the latent image carrier,
Toner may adhere to the non-image portion due to the action of the residual charge of the non-image portion, and the image may be stained. Further, when the toner on the latent image carrier is transferred to a transfer material such as a transfer to obtain a final image, the carrier liquid adhered to the latent image carrier is transferred to the transfer material regardless of the image area and the non-image area. As a result, a large amount of carrier liquid is taken out of the apparatus. Further, the transfer material immediately after the transfer of the developed image is in a wet state with the carrier liquid, and it is necessary to evaporate the carrier liquid before it is discharged out of the apparatus. The amount of heat for evaporating the carrier liquid occupies most of the power consumption of the image forming apparatus. Also,
When the vapor concentration of the carrier liquid evaporated by drying becomes high around the image forming apparatus, some people may feel discomfort.

Therefore, as a wet developing method for solving the above problems, there has been proposed a method in which the developing solution is attached only to the image portion of the electrostatic latent image on the latent image carrier and not to the non-image portion. There is. This developing method uses a developing solution in which a coloring material such as carbon or dye is dispersed or dissolved in a liquid. Unlike the two-component developer, this developer does not move the coloring material in the liquid like the electrophoretic phenomenon, and the entire developer behaves as a toner in the two-component developer. As described above, since there is no equivalent to the carrier liquid in the two-component developer, it is called a one-component developer.

The wet one-component developing method uses a one-component developing solution which does not cause migration of toner particles as described above, and the developing solution is brought into contact with a developing solution carrier so that the developing solution is brought into close proximity to the electrostatic latent image. This is a method of selectively developing only the image portion of the image. Depending on the characteristics of the developing solution, electrostatic conductivity is induced in the conductive developing solution and dielectric polarization in the dielectric developing solution, which induces a charge of a polarity opposite to that of the electrostatic latent image in the developing solution, so that the developing solution is statically moved by Coulomb force. This is a developing method in which the latent image is attached. The advantage of this wet one-component developing method is that the developer does not adhere to the non-image area. Therefore, the image does not have background stains. Also, when the final image is obtained by transferring to a transfer material such as transfer paper, the developing solution adheres only to the image area. It does not take the amount of heat or effort to evaporate. Further, the amount of developer taken out of the apparatus is small. For example, US Pat. No. 30,840.
In No. 43, a conductive liquid ink as a one-component developing solution is supplied to a developing roller having a fine uneven surface, and ink at the apex of the convex portion is squeezed with a blade or the like to prevent background stains. The developing roller, which holds the ink evenly, is brought into contact with the surface of the latent image carrier, and the ink whose opposite polarity charge is induced by the latent image charge is attracted to the latent image charge by the meniscus state via the apex of the developing roller. There is disclosed a wet development method in which the development is performed. Japanese Patent Publication No. 52-17419 also discloses a developing method using a one-component developing solution.

[0006]

However, the developing method disclosed in US Pat. No. 30,840,43 has the advantage that the carrier liquid does not adhere to the non-image area and the ink adheres only to the image area. There is. Then, the pitch of the unevenness of the developing roller becomes the decisive factor of the resolution, and the finer the pitch, the higher the resolution. However, there is a limit to the processing technology for making the pitch fine. Further, since the convex portion of the developing roller is brought into contact with the latent image carrier to develop the image, an image is not formed unless both are evenly contacted. In the case of contacting both of them uniformly as described above, it is necessary to make either the latent image carrier or the developer carrier an elastic body in order to prevent mutual damage, and there is little room for material selection. Further, when the squeeze of the convex portion is insufficient due to abrasion of the blade, scumming occurs.

Therefore, the processing conditions for the unevenness of the developing roller,
Shape (for example, JP-A-51-90828), material (for example, JP-A-49-60534, and JP-A-50-)
98337), physical properties such as ink composition and viscosity (for example, JP-A-50-38546), processes using them (JP-A-47-13946, JP-A-51-118439). Have been proposed.
For example, in Japanese Unexamined Patent Publication No. 51-90828, the recess is a sparse surface,
A developer bearing member having a convex surface having a smooth surface is disclosed in JP-A-49-6.
In Japanese Patent No. 0534, both the developer carrying member and the photosensitive member are made elastic, and in Japanese Laid-Open Patent Publication No. 50-98337, the surface of the developer carrying member is made of cloth. Three
No. 8546 discloses an ink containing a resin in the form of an organosol, JP-A No. 47-13946 discloses a technology for preventing development bleeding, and JP-A No. 51-118439 discloses vibration by applying vibration to an elastic blade. Techniques for restricting the developer on the developer carrier have been disclosed. But,
Even by these, the uniform contact between the latent image carrier and the developer carrier, the squeeze property of the concave portions, etc. were not sufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to consume a small amount of a developing solution, prevent the developing solution from adhering to the latent image carrier more than necessary, and It is an object of the present invention to provide a novel wet developing method and apparatus capable of stably forming an image having a high density and a high resolution with almost no background stain on the image for a long period of time.

[0009]

In order to achieve the above object, the wet developing method according to claim 1 is a two-component method in which a toner is dispersed in a dielectric carrier liquid on a developer carrier having surface irregularities. On the surface of the latent image carrier on which the electrostatic latent image is formed by supporting the developer, the electrostatic latent image is formed on the surface of the latent image carrier by an electric field between the image portion of the latent electrostatic image and the developer carrier. The two-component developer is raised so that the developer carrier and the image area are communicated with each other via the two-component developer, and the charged toner is electrophoresed in the carrier solution of the two-component developer to the image area. It is characterized by attaching charged toner,
3. The wet developing method according to claim 2, wherein a latent image carrier on which an electrostatic latent image is formed by carrying a two-component developing solution having toner dispersed in a dielectric carrier solution on a developing solution carrier having irregularities on its surface The electric field between the image portion of the electrostatic latent image and the developer carrier causes the two-component developer on the developer carrier to rise and the charged toner to be electrophoresed in the carrier liquid. Is concentrated on the tip portion of the ridge, and the developer carrier and the image portion are brought into contact with each other via a two-component developer to attach the charged toner to the image portion.
The wet developing method according to claim 3 is the wet developing method according to claim 1 or 2, wherein an electrostatic latent image in which an image portion is a non-charged portion and a non-image portion is a charged portion is formed on the developer carrier. It is characterized in that the toner having the same polarity as that of the charging portion is used, and the developing solution carrying member is biased so as to have the same potential as that of the charging portion and the reversal development is performed. Also,
5. The wet developing apparatus according to claim 4, further comprising: a developer carrier having an uneven surface, and a developer supply unit for supplying a two-component developer having toner dispersed in a dielectric carrier liquid onto the developer carrier. A developing solution regulating means for regulating the amount of the developing solution supplied by the developing solution supply means and conveyed to the opposing portion of the developing solution carrier and the latent image carrier, and the developing solution carrier, The portion of the two-component developer which is not in contact with the surface of the image bearing member and which faces the image portion of the electrostatic latent image on the latent image bearing member is the image portion and the developer bearing member. A positioning means is provided which is raised by an electric field between the developing solution carrier and the image portion so that the developing solution carrier and the image portion can be communicated with each other via the two-component developing solution.

[0010]

In the present invention, a developer carrying member having irregularities on its surface carries a two-component developer in which a toner is dispersed in a dielectric carrier liquid to form a latent image carrying member on which an electrostatic latent image is formed. Face each other. At this facing portion, an electric field between the image portion of the electrostatic latent image and the developer bearing member causes the two-component developer on the developer bearing member to rise so that the developer bearing member and the image portion. And two components via a two-component developer, whereby the two-component developer is selectively attached only to the image portion of the electrostatic latent image. Further, the charged toner is electrophoresed in the carrier liquid of the two-component developer by the electric field to adhere the charged toner to the image portion, or the tip of the developer portion which is raised toward the image portion by the electric field. The charged toner is concentrated on the image area by electrophoresis in a carrier liquid, and the charged toner is attached to the image area.

[0011]

EXAMPLE An example in which the present invention is applied to a wet developing device for an electrophotographic copying machine will be described below. First, an outline of a copying machine according to an example will be described with reference to FIG. The photosensitive drum 10 as a latent image carrier is
At the time of copying, the drive unit rotates the drive unit in the direction of the arrow at a constant speed, and the main charger 11 uniformly charges the original image IM by the exposure unit to form an electrostatic latent image on the photosensitive drum. , The eraser 12 eliminates charges outside the image forming area. The electrostatic latent image on the photoconductor drum 10 is visualized by a wet developing device 13 to which the present invention is applied, and is fed from a sheet feeding device (not shown) via a conveying roller 14 as indicated by a dashed arrow. It is transferred by the transfer charger 15 to the transfer sheet S as a transfer material. The transfer sheet S is separated from the photosensitive drum 10 by the separation roller 16 and conveyed by the conveyance belt 17, and thereafter, the toner is fixed by the fixing device and discharged to the outside. After the transfer paper S is separated from the photosensitive drum 10, the cleaning unit 18 removes the residual toner, and the charge removal lamp 19
Thus, the residual potential is removed to prepare for the next copy.

Next, the wet developing device 13 will be described. The wet-type developing device 13 of the present embodiment is the photosensitive drum 10
Has a developing container 130 arranged opposite to the surface of the developing container 130 and a tank 22 for storing the developing solution used in the developing container 130 and the cleaning device 18. The developing container 130 and the tank 22 are provided with a developing solution supply pipe 23. And a developer recovery pipe 21. In the developing container 130, a conductive developing roller 131 as a developer carrying member is provided with a minute gap A between the photosensitive drum 10 and a developing solution squeeze roller 132 is provided with a minute gap G between the photosensitive drum 10. The rollers 131 and 132 are pivotally supported, and the rollers 131 and 132 are rotationally driven as indicated by arrows. The developing roller 13
The front end of the scraper 131P, the base end of which is fixed to the developing container 130, is pressed against the surface of No. 1 so that the liquid reservoir and the toner on the surface of the developing roller 131 can be cleaned. The pressure contact with the liquid reservoir means that the scraper 131 extends in the longitudinal direction of the developing roller 131.
The side surface of the free end portion of the P on the side of the developing roller 131 forms a substantially V-shaped facing area between the side surface of the developing roller 131 and the peripheral surface of the developing roller 131, and is discharged from the liquid discharge port of the developer supply pipe 23. This means that the developing solution is set so that it can be stored in this facing area. A scraper 132P is provided in pressure contact with the surface of the developer squeeze roller 132.
A two-component developer is stored in the tank 22.
This two-component developer is one in which charged toner particles composed of a colorant and a resin are dispersed in a carrier liquid having a high insulating property and a low dielectric constant. For example, the two-component developer disclosed in Japanese Patent Publication No. 3-15740 is known. A component developer can be used. Then, in this tank 22, a pump P for pumping the stored developing solution into the developing container 130 or the like via the developing solution supply pipe 23.
A density sensor 24 for detecting the toner density of the stored developer and the like are provided. Reference numeral 24 indicates a developer discharge pipe for stirring the developer in the tank.

The above-described structure is basically the same as that of a conventionally known wet two-component developing device, and the electrostatic latent image on the photosensitive drum 10 is developed as follows. First, the tank 22
The developing solution inside is drawn up by the pump P into the developing container 130 through the developing solution supply pipe 23, and is supplied from the discharge port to the area where the developing roller 131 and the scraper 131P face each other to form a pool of the developing solution. .. The developer drawn up by the rotation of the developing roller 131 from the pool of the developing solution in the facing area is transferred to the photosensitive drum 10 and the developing roller 13.
1 is conveyed to the developing area, which is a portion facing 1 and is supplied to the electrostatic latent image on the photosensitive drum 10. The surface portion of the photosensitive drum 10 that has passed through the developing area is the developer squeeze roller 13
Excess carrier liquid is squeezed from the developed image in the area opposite to 2. With this squeeze, the developer squeeze roller 1
The carrier liquid transferred to 32 is removed by the scraper 132P, and is recovered in the tank 22 via the developer recovery pipe 21 opened at the bottom of the developing container 130. In addition,
Like the developing roller 131, the developing solution squeeze roller 132 is made of a conductive material.
An electric field can be formed between the electrostatic image and the above electrostatic image so as to exert an auxiliary or developing electrode function.

Here, in the conventional wet two-component developing device, the development is performed while the developing area, which is the facing portion between the developing roller 131 and the photosensitive drum 10, is filled with the developing solution. That is, the amount of the developer drawn up from the pool of the developer formed in the area where the scraper 131P and the developing roller 131 face each other by the rotation of the developing roller 131 and conveyed to the developing area is the surface of the developing roller 131 and the photosensitive drum 10. The amount was sufficient to fill the gap with the surface with the developer. Therefore, as described above, the developing solution is uniformly attached on the photoconductor drum 10 to cause various problems.

Therefore, in this embodiment, the developing roller 131
In a situation where the amount of the developer carried on the photoconductor drum 10 and conveyed to the developing area is not influenced by the electrostatic force due to the electrostatic latent image on the photoconductor drum 10, the developer on the developing roller 131 is the surface of the photoconductor drum 10. The amount is adjusted so that it does not come into contact with the two-component developer by using the electrostatic force of the electrostatic latent image or the like only on the image portion of the electrostatic latent image on the photoconductor. For this reason, in the present embodiment, as the developing roller 131, for example, one having unevenness on the surface as shown in the enlarged view of FIG. 1B is used. Further, the developing roller 13 is located at a position downstream of the facing area in the rotation direction of the developing roller 131 and upstream of the facing portion facing the photoconductor drum 10.
A developer scraper 131Q as a developer regulating member whose base end is fixed to the developing container 130 is provided so that the free end edge comes into contact with the surface of 1.

The shape of the unevenness on the surface of the developing roller 131 is such that a developing solution can be held and processing is relatively easy. For example, as shown in FIG. 3A, a screw groove is provided. 4 (b), a shape in which a large number of grooves are provided so as to be orthogonal to each other in the developing roller axis direction and the developing roller rotation direction, and as shown in FIG. 4 (c), grooves are formed in the iris in the developing roller rotation direction. The shape provided, the shape having a large number of grooves in the axial direction of the developing roller as shown in FIG. 4D, FIG.
The shape with many grooves in the direction of rotation of the developing roller,
A shape having a large number of independent recesses as shown in FIG.
And so on. Of these examples of uneven shapes, FIG.
In the examples shown in (a), (b) and (c), since the respective grooves are connected to each other, when the developing solution in a certain portion is consumed, the developing solution is replenished from the surroundings, but FIG. ,
In (e) and (f), since the respective grooves are not connected, the amount of the developer that can be supplied is limited to the amount once retained in the groove and may be insufficient. Therefore, when a relatively high developing solution supply capacity is required, as shown in FIG.
The uneven shape as shown in (b) and (c) is preferable.

The developing solution scraper 131Q collects the developing solution which is pumped up by the rotation of the developing roller 131 from the pool of the developing solution formed in the area where the developing roller 131 and the scraper 131P face each other and is conveyed to the developing area. In the situation where the amount is averaged above, and the amount of the amount is not influenced by the electrostatic force due to the electrostatic latent image on the photosensitive drum 10, the developing solution on the developing roller 131 is
The amount is regulated to such an extent that the gap between the surface and the surface of the photosensitive drum 10 is not filled. That is, for example, as shown in FIG. 1B, which is a schematic view of the developing area, the distance between the surface of the photosensitive drum 10 and the developing roller 131 is A (about 500 μm or less).
Then, the thickness C of the liquid film of the developing solution on the developing roller 131 is set to be smaller than the gap A so that a space B exists between the surface L of the developing solution on the developing roller 131 and the surface of the photosensitive drum. Thin (about 450 μm). Here, FIG. 1 (a)
Reference numeral 10a indicates a photosensitive layer, and reference numeral 10b indicates a conductive substrate. Note that, unlike the example shown in the figure, the amount of the developing solution is set so that the apex of the convex portion of the developing roller 131 is not covered with the developing solution.
The amount of the developer may be regulated or the gap A may be set so that the size of the gap B between the liquid surface of the developer and the surface of the photosensitive drum 10 is larger than the gap A.

The developing principle in the case where a predetermined amount of the two-component developing solution is carried on the developing roller 131 having an uneven surface so as to face the surface of the photosensitive drum 10 is not clear, but it is as follows. Conceivable. 2 (a)-
(F) shows a state of adhesion of the two-component developing solution and migration of the toner particles in the carrier solution in this order with time. In the illustrated example, the photosensitive drum 10 is uniformly charged positively, and the non-charged portion in which the uniformly charged electric charge is erased by light irradiation is the non-image portion, and the charged portion not irradiated with light is the image portion. The latent image is formed, and the normal development is performed to selectively attach the negative polarity toner to the image portion. First, as shown in FIG. 2A, the two-component developer is held on the surface of the conductive developing roller 131 and the photosensitive drum 10 is held.
Facing the electrostatic latent image above. Then, FIG. 2 (b), (c)
As shown in, since the developer is a dielectric substance, it causes dielectric polarization, and the developer is selectively attracted to the electrostatic latent image, and the liquid surface rises. At this time, as shown in FIG. 2C, the toner in the carrier liquid is accelerated by the repulsive force due to the induced charges generated on the conductive developing roller 131 by the electrostatic latent image and the attraction force due to the latent image charge. It migrates to the surface layer of the developer. Then, as shown in FIG. 2D, the raised developer surface portion selectively adheres to the charged portion of the electrostatic latent image, so that only the charged portion of the electrostatic latent image and the developing roller 131 are separated from each other. The bridge will be bridged over. Then, as shown in FIG. 2E, it is considered that the electrophoretic development of the charged toner, which is the normal two-component development, is performed in the developer in the crosslinked state. Unlike the example shown in the figure, a charged toner having the same polarity as that of the uniform charge is used, and a voltage not shown is applied to the developing roller 131 by a power source (not shown) to apply the charged toner to the uncharged portion. Even in the case of reversal development in which the toner is selectively attached, an electric field between the image portion of the electrostatic latent image and the developing roller 131 causes the developer surface corresponding to the image portion to rise and contact the surface of the photoconductor. As a result, a bridge is formed between only the image portion of the electrostatic latent image and the developing roller 131, and an electrophoretic phenomenon of charged toner, which is a normal two-component development, occurs in the developer in the bridged state. ..

According to the developing method of this embodiment, since the attachment of the two-component developing solution to the electrostatic latent image is governed by the one-component developing method, the developing solution is selected only in the image portion of the electrostatic latent image. Adhere to the electrostatic latent image and do not adhere to the background portion of the electrostatic latent image. Therefore, the non-image area is not wet with the developing solution, there is no background stain, the developing solution consumption is small, and the amount of heat for evaporating the excess developing solution and the labor are not required.

Further, a bridge is formed between only the image portion of the electrostatic latent image and the developing roller 131, and the electrophoretic migration of the charged toner, which is a normal two-component development in the developer in the bridged state. Since a phenomenon occurs, the fine particle toner migrates individually in the carrier liquid, and the electrostatic latent image is finely developed to obtain a high resolution, high gradation, and high quality image. Due to the electrophoretic phenomenon of the charged toner in the carrier liquid, even if the developing liquid sticks out from the image portion of the electrostatic latent image and adheres, the charged toner containing the colorant in the carrier liquid electrophoreses to form an image. Only the part can be visualized. For example, the electrostatic latent image shown in FIG. 6A is reproduced as an image that is faithful to the electrostatic latent image as indicated by the shaded area in FIG. 6B. On the other hand, in the one-component developing method, as shown in FIGS. 5A and 5B, the developer is selectively attracted to the image portion of the electrostatic latent image. As shown in the figure, when the developer sticks out from the image part of the electrostatic latent image due to the viscosity and dielectric property of the developer, the part that sticks out from the image part of the electrostatic latent image and the developer adheres is colored and the image becomes It becomes thicker than the electrostatic latent image. For example, the electrostatic latent image shown in FIG. 6A is reproduced as a thick image as shown by hatching in FIG. 6C. This is because in the one-component developer, the whole developing solution acts as a colorant, and the whole area where the developing solution adheres is visualized.

Further, since the surface of the developing roller 131 is made uneven, the amount of the developing solution carried on the developing roller 131 and conveyed to the developing area is adjusted so that the surface of the developing roller 131 contacts the surface of the photosensitive drum 10. And it is relatively easy to regulate the amount to a sufficient level for good development. That is, even if the surface of the developing roller 131 is made relatively flat, the surface of the developer film on the surface of the developing roller 131 opposes the surface of the photoconductor with a small gap so as not to contact the surface of the photoconductor drum 10. Can be configured as follows. However, in this case, it is difficult to manage the gap between the developing roller 131 and the photoconductor drum 10 and the developer film. Further, when a thin film of the developing solution is formed, high-speed development cannot be followed with the amount of the developing solution that can exist in the minute gap. If unevenness is formed on the surface of the point developing roller 131, a sufficient amount of the developing solution can be transported to the developing area by the relatively easy management of the gap between the developing roller 131 and the photosensitive drum 10.

Further, as described above, since the resolution of the image is finally determined by the electrophoresis of the charged toner in the carrier liquid, the developing roller 131 of this embodiment has a conventional resolution in which the resolution depends on the uneven pitch of the surface. As compared with the developing roller used in the one-component developing method, there are less restrictions on the shape and pitch of the surface irregularities and the surface material. That is, since the developing roller used in the conventional one-component developing method must be wiped so that the developer on the surface is almost completely eliminated, it is preferable that the area of the convex is too large or the surface is rough. However, it was not possible to perform such development, and there were many restrictions on the surface shape and material of the developing roller. For this reason, high processing technology is required and the cost becomes high.

The developing roller 131 is a photosensitive drum 1.
Since they do not contact the 0 surface, it is possible that both are rigid bodies, and it is not necessary to strictly control the contact between them.

In the above embodiment, the developer scraper 131Q was used as the developer restricting member, but instead of this, for example, as shown in FIGS. 4 (a) and 4 (b), a roller-like developer restricting member is used. The member 131R may be used. Here, the wet type developing device of FIG. 4A forms a pool of the two-component developer in the developing container 130, and the developing roller 131 arranged so as to be partially embedded in the pool of the developer. The developer is conveyed to the surface of the photosensitive drum 10 by the rotation of. In this case as well, the surface of the developing roller 131 has the above-mentioned concavo-convex shape, and due to the developer regulating member 131,
The amount of the developing solution conveyed to the developing area is regulated to such an amount that the gap between the surface of the developing roller 131 and the surface of the photosensitive drum 10 is not filled.

[0025]

According to the present invention, the adhesion of the two-component developing solution to the electrostatic latent image is governed by the one-component developing method, so that the developing solution is the image portion of the electrostatic latent image. It selectively adheres only to the background and does not adhere to the background part of the electrostatic latent image. Therefore, the non-image area is not wet with the developing solution, there is no background stain, the developing solution consumption is small, and the amount of heat for evaporating the excess developing solution and the labor are not required. Further, since the unevenness is formed on the surface of the developer carrying member, the amount of the developer carried on the developer carrying member and conveyed to the developing area can be adjusted so that the liquid surface does not contact the surface of the latent image carrying member in the developing area. And it is relatively easy to make the amount sufficient for good development.

In particular, according to the first aspect of the invention, a bridge is formed between only the image portion of the electrostatic latent image and the developer carrying member, and in the developer in this bridged state, an ordinary condition is maintained. Since the electrophoretic phenomenon of the charged toner, which is a two-component development, occurs, the fine particle toner individually migrates in the carrier liquid, and the electrostatic latent image is finely developed to obtain a high resolution, high gradation, and high quality image. can get. Due to the electrophoretic phenomenon of the charged toner in the carrier liquid, even if the developing liquid sticks out from the image portion of the electrostatic latent image and adheres, the charged toner containing the colorant in the carrier liquid electrophoreses to form an image. Only the portion is visualized, and a developed image faithful to the electrostatic latent image can be obtained. Further, since the resolution of the image is finally determined by the electrophoresis of the charged toner in the carrier liquid, the developer carrier of the present invention is used in the conventional one-component developing method in which the resolution depends on the uneven pitch of the surface. As compared with the developer carrying member, there are less restrictions on the shape and pitch of the surface irregularities and the surface material. Therefore, it is possible to use a low-priced material without requiring high-level processing technology, and it is possible to reduce the cost.

According to the second aspect of the present invention, the electric field between the image portion of the electrostatic latent image and the developing solution carrying member causes the tip of the developing solution portion protruding toward the image portion. Since the charged toner is concentrated by electrophoresis in the carrier liquid to adhere the charged toner to the image portion, the charged toner dispersed in the carrier liquid is concentrated and adhered to the image portion to develop a sufficient density. You can get a statue.

According to the invention of claim 3, claim 1
Alternatively, in the wet developing method according to the item 2, an electrostatic latent image in which an image portion is a non-charged portion and a non-image portion is a charged portion is used, and the developer carrying member uses a charged toner having the same polarity as the charged portion.
Further, since the developing solution carrying member is biased so as to be at the same potential as the charged portion and the reversal development is performed, the reversal development exhibiting the same effect as the wet development method according to claim 1 or 2 is performed. be able to.

Further, according to the invention of claim 4, since the developing solution carrier having irregularities on its surface is positioned at a position where it does not contact the latent image carrier carrying surface, the developing solution carrier and the latent image carrying body are separated. Both can be rigid, and there is no need to tightly control each other's contact.

[Brief description of drawings]

FIG. 1A is a front view showing a schematic configuration of an electrophotographic copying machine according to an embodiment, and FIG. 1B is a schematic view of a developing area of the copying machine.

2A to 2F are explanatory views of a wet development method according to an embodiment.

FIGS. 3A to 3F are explanatory views of configuration examples of a developing roller surface of the copying machine.

FIG. 4A is a front view showing a modified example of a developing solution regulating means in the copying machine, and FIG. 4B is an explanatory view of the function of the developing solution regulating means.

5A to 5C are explanatory views of a conventional one-component wet development method.

6A is an explanatory diagram of an example of an electrostatic latent image, FIG. 6B is an explanatory diagram of an example of a developed image by a wet development method according to an embodiment,
(C) is an explanatory view of an example of a developed image by the conventional one-component wet development method.

[Explanation of symbols]

 10 Photoreceptor Drum 130 Development Container 131 Development Roller 131P Scraper 131Q Developer Scraper 132 Developer Squeeze Roller L Liquid Level

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[Procedure amendment]

[Submission date] August 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

The wet one-component developing method uses a one-component developing solution which does not cause migration of toner particles as described above, and the developing solution is brought into contact with a developing solution carrier so that the developing solution is brought into close proximity to the electrostatic latent image. This is a method of selectively developing only the image portion of the image. Depending on the characteristics of the developing solution, electrostatic conductivity is induced in the conductive developing solution and dielectric polarization in the insulating developing solution is induced in the developing solution by a charge having a polarity opposite to that of the electrostatic latent image, and the developing solution is statically charged by Coulomb force. This is a developing method in which the latent image is attached. The advantage of this wet one-component developing method is that the developer does not adhere to the non-image area. Therefore, the image does not have background stains. Also, when the final image is obtained by transferring to a transfer material such as transfer paper, the developing solution adheres only to the image area. It does not take the amount of heat or effort to evaporate. Further, the amount of developer taken out of the apparatus is small. For example, US Pat. No. 30,840.
In No. 43, a conductive liquid ink as a one-component developing solution is supplied to a developing roller having a fine uneven surface, and ink at the apex of the convex portion is squeezed with a blade or the like to prevent background stains. The developing roller, which holds the ink evenly, is brought into contact with the surface of the latent image carrier, and the ink whose opposite polarity charge is induced by the latent image charge is attracted to the latent image charge by the meniscus state via the apex of the developing roller. There is disclosed a wet development method in which the development is performed. Japanese Patent Publication No. 52-17419 also discloses a developing method using a one-component developing solution.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

In order to achieve the above object, a wet developing method according to a first aspect of the present invention is a two-component method in which a toner is dispersed in an insulating carrier liquid on a developer carrier having irregularities on its surface. On the surface of the latent image carrier on which the electrostatic latent image is formed by supporting the developer, the electrostatic latent image is formed on the surface of the latent image carrier by an electric field between the image portion of the latent electrostatic image and the developer carrier. The two-component developer is raised so that the developer carrier and the image area are communicated with each other via the two-component developer, and the charged toner is electrophoresed in the carrier solution of the two-component developer to the image area. It is characterized by attaching charged toner,
3. The latent image carrier according to claim 2, wherein the electrostatic latent image is formed by supporting a two-component developer having toner dispersed in an insulating carrier liquid on a developer carrier having irregularities on its surface. The electric field between the image portion of the electrostatic latent image and the developer carrier causes the two-component developer on the developer carrier to rise and the charged toner to be electrophoresed in the carrier liquid. Is concentrated on the tip portion of the ridge, and the developer carrier and the image portion are brought into contact with each other via a two-component developer to attach the charged toner to the image portion.
The wet developing method according to claim 3 is the wet developing method according to claim 1 or 2, wherein an electrostatic latent image in which an image portion is a non-charged portion and a non-image portion is a charged portion is formed on the developer carrier. It is characterized in that a charged toner having the same polarity as that of the charging portion is used, and the developing solution carrying member is biased so as to have a potential similar to that of the charging portion, and the reversal development is performed. Also,
5. The wet developing apparatus according to claim 4, further comprising: a developer carrying member having irregularities on its surface; and a developer supplying means for supplying a two-component developer having toner dispersed in an insulating carrier liquid on the developer carrying member. A developing solution regulating means for regulating the amount of the developing solution supplied by the developing solution supply means and conveyed to the opposing portion of the developing solution carrier and the latent image carrier, and the developing solution carrier, The non-contact with the surface of the image carrier, and facing the image portion of the electrostatic latent image on the latent image carrier of the carried two-component developer.
And a positioning means for positioning the developing solution carrier and the image portion so that they can communicate with each other via a two-component developer by raising an electric field between the image portion and the developing solution carrier. It is characterized by that.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

In the present invention, a two-component developer in which toner is dispersed in an insulating carrier liquid is carried on a developer carrier having irregularities on the surface of the latent image carrier on which an electrostatic latent image is formed. Face each other. At this facing portion, an electric field between the image portion of the electrostatic latent image and the developer bearing member causes the two-component developer on the developer bearing member to rise so that the developer bearing member and the image portion. And two components via a two-component developer, whereby the two-component developer is selectively attached only to the image portion of the electrostatic latent image. Further, the charged toner is electrophoresed in the carrier liquid of the two-component developer by the electric field to adhere the charged toner to the image portion, or the tip of the developer portion which is raised toward the image portion by the electric field. The charged toner is concentrated on the image area by electrophoresis in a carrier liquid, and the charged toner is attached to the image area.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

Next, the wet developing device 13 will be described. The wet-type developing device 13 of the present embodiment is the photosensitive drum 10
Has a developing container 130 arranged opposite to the surface of the developing container 130 and a tank 22 for storing the developing solution used in the developing container 130 and the cleaning device 18. The developing container 130 and the tank 22 are provided with a developing solution supply pipe 23. And a developer recovery pipe 21. In the developing container 130, a conductive developing roller 131 as a developer carrying member is provided with a minute gap A between the photosensitive drum 10 and a developing solution squeeze roller 132 is provided with a minute gap G between the photosensitive drum 10. The rollers 131 and 132 are pivotally supported, and the rollers 131 and 132 are rotationally driven as indicated by arrows. The developing roller 13
The front end of the scraper 131P, the base end of which is fixed to the developing container 130, is pressed against the surface of No. 1 so that the liquid reservoir and the toner on the surface of the developing roller 131 can be cleaned. The pressure contact with the liquid reservoir means that the scraper 131 extends in the longitudinal direction of the developing roller 131.
The side surface of the free end portion of the P on the side of the developing roller 131 forms a substantially V-shaped facing area between the side surface of the developing roller 131 and the peripheral surface of the developing roller 131, and is discharged from the liquid discharge port of the developer supply pipe 23. This means that the developing solution is set so that it can be stored in this facing area. A scraper 132P is provided in pressure contact with the surface of the developer squeeze roller 132.
The developer squeeze roller 132 and the scraper
132P can be omitted. The above tank 22
A two-component developer is stored inside. This two-component developer is one in which charged toner particles composed of a colorant and a resin are dispersed in a carrier liquid having a high insulating property and a low dielectric constant,
For example, a two-component developer known in Japanese Patent Publication No. 3-15740 can be used. The tank 22 is provided with a pump P for pumping the stored developer into the developing container 130 and the like via the developer supply pipe 23, a concentration sensor 24 for detecting the toner concentration of the stored developer, and the like. ing. Reference numeral 25 indicates a developer discharge pipe for stirring the developer in the tank.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The developing principle in the case where a predetermined amount of the two-component developing solution is carried on the developing roller 131 having an uneven surface so as to face the surface of the photosensitive drum 10 is not clear, but it is as follows. Conceivable. 2 (a)-
(F) shows a state of adhesion of the two-component developing solution and migration of the toner particles in the carrier solution in this order with time. In the illustrated example, the photosensitive drum 10 is uniformly charged positively, and the non-charged portion in which the uniformly charged electric charge is erased by light irradiation is the non-image portion, and the charged portion not irradiated with light is the image portion. The latent image is formed, and the normal development is performed to selectively attach the negative polarity toner to the image portion. First, as shown in FIG. 2A, the two-component developer is held on the surface of the conductive developing roller 131 and the photosensitive drum 10 is held.
Facing the electrostatic latent image above. Then, FIG. 2 (b), (c)
As shown in, since the developer is an insulator, it causes dielectric polarization, and the developer is selectively attracted to the electrostatic latent image, and the liquid surface rises. Toner carrier liquid At this time, as shown in FIG 2 (c) is a repulsive force due to the induced charge generated in the developing roller 131 of the conductive by an electrostatic latent image, the current image liquid in the suction force due to the latent image charges Figure 2 while migrating to the surface layer
As shown in (d), the raised developer surface portion selectively adheres to the charged portion of the electrostatic latent image, and a bridge is formed between only the charged portion of the electrostatic latent image and the developing roller 131. It will be in a worn state. Then, as shown in FIG. 2E, it is considered that the electrophoretic development of the charged toner, which is a normal two-component development, is accelerated in the developer in the crosslinked state . Note that unlike the example shown in the figure, a charged toner having the same polarity as that of uniform charging is used,
Even in the case of reversal development in which a voltage substantially equal to the uniform charging potential is applied to the developing roller 131 by a power source (not shown) to selectively attach the charged toner to the non-charged portion, the electrostatic latent image is not detected. Due to the electric field between the developing roller 131 and the developing roller 131, the surface of the developing solution corresponding to the image portion is raised and comes into contact with the surface of the photoconductor, thereby forming a bridge between only the image portion of the electrostatic latent image and the developing roller 131. In the crosslinked state, the electrophoretic phenomenon of the charged toner, which is the normal two-component development, occurs in the crosslinked developer.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Further, a bridge is formed between only the image portion of the electrostatic latent image and the developing roller 131, and the electrophoretic migration of the charged toner, which is a normal two-component development in the developer in the bridged state. Since a phenomenon occurs, the fine particle toner migrates individually in the carrier liquid, and the electrostatic latent image is finely developed to obtain a high resolution, high gradation, and high quality image. Due to the electrophoretic phenomenon of the charged toner in the carrier liquid, even if the developing liquid sticks out from the image portion of the electrostatic latent image and adheres, the charged toner containing the colorant in the carrier liquid electrophoreses to form an image. Only the part can be visualized. For example, for the electrostatic latent image shown in FIG. 6A, as shown by the broken line in FIG.
If the developing solution sticks out of the image area of the electrostatic latent image and adheres to the
In this case, the charged toner containing the colorant in the carrier liquid
By migrating, it is reproduced as an image that is faithful to the electrostatic latent image as shown by the hatching in FIG. On the other hand, in the one-component developing method, as shown in FIGS. 5A and 5B, the developer is selectively attracted to the image portion of the electrostatic latent image. As shown, when the developer sticks out from the image part of the electrostatic latent image due to the viscosity of the developer, etc. ,
The portion of the electrostatic latent image that protrudes from the image portion to which the developing solution adheres is also colored, and the image becomes thicker than the electrostatic latent image. For example, the electrostatic latent image shown in FIG. 6A is reproduced as a thick image as shown by hatching in FIG. 6C. This is because in the one-component developer, the whole developing solution acts as a colorant, and the whole area where the developing solution adheres is visualized.

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuichi Aoyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kazuo Tsufuko 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh

Claims (4)

[Claims] 1. A two-component developer in which a toner is dispersed in a dielectric carrier liquid is carried on a developer carrier having irregularities on its surface to face the surface of the latent image carrier on which an electrostatic latent image is formed. An electric field between the image portion of the electrostatic latent image and the developer carrying member causes the two-component developer on the developer carrying member to rise so that the developer carrying member and the image portion have two components. A wet development method characterized in that the charged toner is allowed to adhere to the image area by causing the charged toner to electrophorese in a carrier liquid of a two-component developer while communicating with the developer. 2. A two-component developer having a toner dispersed in a dielectric carrier liquid is carried on a developer carrier having irregularities on its surface to face the surface of the latent image carrier on which an electrostatic latent image is formed. , The electric field between the image portion of the electrostatic latent image and the developer carrier causes the two-component developer on the developer carrier to rise, and the charged toner is electrophoresed in the carrier liquid to cause the tip of the rise. A wet developing method, characterized in that the charged toner is adhered to the image portion by concentrating the toner on the image portion and contacting the developer carrier with the image portion through a two-component developer. 3. An electrostatic latent image in which an image portion is a non-charged portion and a non-image portion is a charged portion is used, and a charged toner having the same polarity as that of the charged portion is used for the developer carrier. 3. The wet developing method according to claim 1, wherein the developing solution carrier is biased so as to have a potential similar to that of the charged portion, and the reversal development is performed. 4. A developer carrier having an uneven surface, a developer supplying means for supplying a two-component developer having toner dispersed in a dielectric carrier liquid on the developer carrier, and the developer. A developing solution regulating means for regulating the amount of the developing solution supplied by the supplying means and conveyed to the opposing portion of the developing solution carrier and the latent image carrier; A portion of the two-component developing solution that is not in contact with the surface and faces the image portion of the electrostatic latent image on the latent image carrier is located between the image portion and the developer carrier. A wet developing device comprising: a positioning means that is raised by an electric field to position the developing solution carrier and the image portion at a position where they can communicate with each other via a two-component developing solution.