JP3235889B2 - Wet developing device and developer carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet type developing device and a developing solution carrier used in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like. The present invention relates to a wet developing device for supplying a developing solution to a developing device to develop a latent image, and a developing solution carrier.

[0002]

2. Description of the Related Art Conventionally, dry developing methods and wet developing methods are generally classified as developing methods used for image formation. In the wet development method, for example, a developing solution in which a toner made of, for example, carbon black coated with a resin is dispersed in a carrier liquid made of an aliphatic hydrocarbon such as Isopar (trade name) is used as a latent image on which an electrostatic latent image is formed. The developer is supplied between the surface of the carrier and a counter electrode arranged at a constant interval on the surface to bring the developing solution into contact with the surface of the latent image carrier, and utilizes the electrophoresis phenomenon of the charged toner in the carrier liquid. To develop an electrostatic latent image. The developer used in this developing method is called a two-component developer because a carrier liquid is used for charging and transferring the toner. The developing method using the two-component developing solution has an advantage that high resolution can be obtained because the toner particles are finer than a general dry developing method.

However, in the wet developing method using the two-component developing solution, the developing solution is applied to a portion of the electrostatic latent image to which toner is to be adhered (hereinafter referred to as an image portion. The portion that should not be adhered is called not only the non-image portion but also the non-image portion of the latent image carrier. May be soiled. When the final image is obtained by transferring the toner on the latent image carrier to a transfer material such as transfer paper, the carrier liquid adhered to the latent image carrier regardless of the image portion and the non-image portion is transferred to the transfer material. Therefore, a large amount of the 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 being 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.

Therefore, as a wet developing method for solving the above-mentioned problems, a method has been proposed in which a developing solution is applied only to an image portion of an electrostatic latent image on a latent image carrier and not to a non-image portion. I have. This method includes a one-component developing method and a non-contact two-component developing method described below. In the one-component developing method, a developer in which a coloring material such as carbon or dye is dispersed or dissolved in a liquid is used. Unlike the two-component developer, this developer does not move the coloring material in the liquid unlike the electrophoretic phenomenon, and the entire developer acts like a toner in the two-component developer. Thus, since there is no equivalent to the carrier liquid in the two-component developer, it is called a one-component developer.

[0005] The one-component developing method is a method in which this developing solution is arranged close to the developer carrying member so as to come into contact with the developing solution, and only the image portion of the electrostatic latent image is selectively developed. Depending on the characteristics of the developer, a charge is induced in the conductive developer by electrostatic induction, and in a dielectric developer by dielectric polarization, a charge having a polarity opposite to that of the electrostatic latent image is induced in the developer, and the Coulomb force causes the developer to be static. This is a developing method for attaching to an electrostatic latent image. The advantage of this one-component developing method is that the developing solution does not adhere to the non-image area.
For this reason, the background is not stained in the image. In addition, when a final image is obtained by transferring the image onto a transfer material such as transfer paper, the developer adheres only to the image portion. No heat or effort to evaporate. The amount of the developer taken out of the apparatus is small. For example, U.S. Pat. No. 3,084,043 discloses that a conductive liquid ink as a one-component developer is supplied to a developing roller having a fine uneven surface, and the ink at the top of the convex portion is squeezed with a blade or the like to prevent background contamination. As a result, the developing roller holding the ink uniformly only in the concave portion is brought into contact with the surface of the latent image carrier, and the ink in which the opposite polarity charge is induced by the latent image charge is latently passed through the vertex of the developing roller in a meniscus state. There has been disclosed a wet developing method in which an image charge is attracted and adhered to develop.

There is also a one-component developing method in which the developing roller and the latent image carrier are developed without contact. In this method, the one-component developer is used, and the developer is arranged close to the latent image without being brought into contact with the latent image by a developing roller to selectively attach the developer to the latent image. According to this method, since the developing roller does not come into contact with the latent image, there is no need to squeeze the convex portion of the developing roller unlike the above-described one-component developing method, and there is no fear of background contamination.

Next, the non-contact two-component developing method uses the two-component developing solution described above and arranges the two-component developing solution close to the latent image without being brought into contact with the latent image by a developer carrier. This is a development method that has a combination of features of the development method. In this development method, high-quality images are exhibited because development is performed by two-component development toner migration at the same time as or before or after the selective adhesion of the developer to the latent image, which is a feature of the one-component development method. In this developing method, unlike a normal wet two-component developing method, the developing solution adheres to the latent image by a one-component developing method. Does not adhere to the image area. For this reason, the non-image portion is not wet with the developing solution, there is no background contamination, the consumption of the developing solution is small, and the amount of heat for evaporating the excess developing solution is not required. Since the developer carrier and the latent image carrier do not come into contact with each other, both may be rigid bodies, and there is no need to strictly control contact with each other. Moreover, when the developer fills the gap between the latent image carrier and the developer carrier only in the image area, the fine particle toner migrates in the carrier liquid between the latent image carrier and the developer carrier. Develop the latent image finely. Therefore, high resolution can be obtained.

However, in the above-mentioned non-contact two-component developing method, the surface of the developer carrying member for supplying the developing solution to the developing section where the latent image on the latent image is developed is developed even on a relatively flat surface. Although the liquid can be supplied, it is difficult to form a uniform thin film of the developer such that the developer does not fill a minute gap between the latent image carrier and the developer carrier on a flat surface. . Further, even when a thin film is formed, high-speed development cannot be followed with the amount of the developing solution that can exist between the minute gaps. This problem can be solved, for example, by using a developer carrier 90 having a surface with irregularities as shown in FIG. By using such a developer carrier, contact between the developer and the latent image carrier can be prevented, and the developer can be uniformly carried on the surface of the developer carrier.

[0009]

However, the developing method disclosed in the above-mentioned U.S. Pat. No. 3,084,043 has the advantage that the carrier liquid does not adhere to the non-image area and the ink adheres only to the image area. However, the pitch of the unevenness of the developing roller determines the resolution, and the finer the pitch, the higher the resolution. However, there is a problem that the processing technology is limited in order to make the pitch fine. In addition, since the development is performed by bringing the convex portion of the developing roller into contact with the latent image carrier, an image is not formed unless the two uniformly contact each other. When the two are brought into uniform contact as described above, either the latent image carrier or the developer carrier must be made elastic to prevent damage to each other, and there is little room for material selection. was there. In addition, when the squeeze of the convex portion is insufficient due to abrasion of the blade or the like, there is a problem that background dirt is generated.

Also, in the non-contact two-component developing method using the developer carrier 90 having the irregularities formed on the surface,
In order to form fine pitch irregularities, there is a problem that an advanced processing technique is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to use a simpler developer carrier which does not require uneven surface processing, and to reduce the consumption of the developer. A novel wet developing apparatus capable of stably forming a high-density, high-resolution image without long-term development liquid adhering to a latent image carrier and having almost no background smear on an image, and a novel wet developing apparatus thereof. The object is to provide a developer carrier.

[0012]

Means for Solving the Problems To achieve the above object, the invention of claim 1 is employed in a wet developing apparatus for developing a latent image on a latent image carrier using a liquid developer, The receding contact angle is reduced when the surface of the developing solution carrier is heated and is brought into contact with a liquid in the developing solution carrier that is disposed to face the latent image carrier and carries the developer. And a partially heated in a state of being in contact with the liquid, or being brought into contact with the liquid in a state of being partially heated, so that the surface has a receding contact angle corresponding to a heating temperature. Characterized by forming the indicated area. According to a second aspect of the present invention, there is provided a wet developing apparatus for developing a latent image on a latent image carrier using a liquid developer, wherein a material having a receding contact angle reduced when heated and in contact with a liquid is used. Is formed on the surface, a heated region and a non-heated region are formed, and the surface and the liquid, the vapor, or the solid that becomes a liquid or a liquid or a vapor at or below the temperature at which the receding contact angle of the material starts to decrease. By contacting a selected contact material, a developer carrier in which a region having a receding contact angle corresponding to a heating temperature is formed on the surface, and a developer supply unit for attaching the developer to the heated region It is characterized by having. According to a third aspect of the present invention, there is provided a wet developing apparatus for developing a latent image on a latent image carrier using a liquid developer, wherein a material having a receding contact angle which is reduced when heated and in contact with a liquid is heated. The surface is partially constituted by the material, and is selected from the surface and a liquid or a vapor, or a solid that becomes a liquid or a liquid or a vapor at or below the temperature at which the receding contact angle of the material starts to decrease. Contacting the contact material to be contacted, a developer carrier having an area showing a receding contact angle corresponding to the heating temperature formed on the surface, and a developer supply means for attaching the developer to the heated area. It is characterized by having .

[0013]

In the present invention, part or all of the surface of the developer carrying member is made of a material whose receding contact angle decreases when it is brought into contact with a liquid in a heated state. Partially heated or partially heated in contact with vapor or a contact material selected from a liquid or a solid that generates vapor at or below the temperature at which the receding contact angle of the material decreases. By contacting with the contact material, a region having a receding contact angle corresponding to the heating temperature is formed on the surface, and uniform developer droplets are formed on the surface of the developer carrier. Then, the droplets are selectively caused to fly to the latent image for development. Here, the reason why uniform droplets of the developer can be formed by forming regions having different receding contact angles on the surface of the material constituting the surface of the developer carrier is as follows. That is, the adhesion of the liquid on the solid surface occurs mainly by tacking of the liquid on the solid surface. Tucking appears to be a kind of friction when a liquid slides on a solid surface. Therefore, the following relationship is established when the receding contact angle θr is assumed to be γf (saito, Kitajima et al., “Journal of the Japan Adhesion Society”, Vol. 22, No. 12, No. 1986).

(Equation 1) Here, γ: surface tension of the solid in vacuum γsl: solid-liquid interfacial tension γlv: surface tension when the liquid is in contact with the saturated vapor πe: equilibrium surface tension γf: frictional tension γs: solid of the solid without the adsorption layer Therefore, when the value of the receding contact angle θr decreases, the friction tension γ
The value of f increases. That is, the liquid becomes less slippery on the solid surface, and the liquid adheres to the solid surface.

[0014]

An embodiment in which the present invention is applied to a wet developing apparatus 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 photoreceptor drum 10 as a latent image carrier is rotationally driven in a direction indicated by an arrow at a constant speed by a driving device during copying, and is uniformly charged by the main charger 11.
The original image IM is projected by the exposure device to form an electrostatic latent image on the photosensitive drum, and the eraser 12 removes electricity outside the image forming area. The electrostatic latent image on the photoreceptor 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 broken arrow. The image is transferred to a transfer sheet S as a transfer material by a transfer charger 15. This transfer paper S
Is separated from the photoreceptor drum 10 by a separation roller 16 and is conveyed by a conveyance belt 17. Thereafter, the toner is fixed by a fixing device and is discharged to the outside. After the transfer paper S is separated from the photosensitive drum 10, the cleaning unit 18
As a result, the residual toner is removed, and the residual potential is removed by the charge removing lamp 19 to prepare for the next copy.

Next, the wet developing device 13 will be described. The wet developing device 13 of the present embodiment includes the photosensitive drum 10
And a tank 22 for storing the developing solution used in the cleaning device 18 and the developing container 130. The developing container 130 and the tank 22 are connected to the developing solution supply pipe 23. And a developer collection tube 21.

In the developing container 130, a conductive developing roller 131 serving as a developer carrier is provided with a photosensitive drum 10.
And the developer squeeze roller 13
2 (which is provided when a two-component developer is used) is supported by the photosensitive drum 10 with a small gap G therebetween, and the developer squeeze roller 132 is driven to rotate in the direction of the arrow. . The rotation direction of the developing roller 131 may be either direction. Here, the gap A corresponds to the developing roller 1
The size of the developer carried on the developing roller 131 may be about 450 μm or less, as long as the size of the developer carried on the developing roller 131 does not contact the surface of the photosensitive drum 10. In some cases, the gap A may be set to about 500 μm or less. Developing roller 1
Numeral 31 is arranged so that a part thereof is immersed in a developing solution in a developing solution container 131C whose base end is fixed to the developing container 130.

The developing solution container 131C is provided so as to store the developing solution discharged from the liquid discharging port of the developing solution supply pipe 23.

Above the developing roller 131, a developing roller 1 is provided.
A squeeze roller 131 </ b> Q is provided opposite to the squeeze roller 31. The squeeze roller 131 </ b> Q is used to remove excess developer when the developer is excessively attached to the surface of the development roller 131.

As shown in FIG. 7 described later, below the developing roller 131 in the developing solution container 131C, one end is made to be an axis, and the other end is in contact with the surface of the developing roller 131 (solid line in the drawing). ), And a blade 131B configured to be separated (indicated by a broken line in the figure).
Are arranged. The blade 131 </ b> B is used to keep fresh developing solution adhered to the surface of the developing roller 131 and to clean dirt on the surface of the developing roller 131. For example, blade 1
By making the surface of the developing roller 131 always in contact with the surface of the developing roller 131, a new developing solution can be constantly adhered to the surface of the developing roller 131.
Is controlled so that the surface of the developing roller 131 is brought into contact and non-contact with the surface of the developing roller 131 as appropriate, so that the dirt on the surface of the developing roller 131 can be properly cleaned. Which of the above configurations is adopted depends on whether the blade 131 is used.
The selection may be made depending on which function B is to exhibit.

On the surface of the developer squeeze roller 132, a scraper 132S is provided in pressure contact.

In the tank 22, a two-component developer is stored in the case of non-contact two-component development (as shown), and a one-component developer is stored in the case of one-component development. This two-component developer is obtained by dispersing charged toner particles comprising a colorant and a resin in a carrier liquid having a high insulating property and a low dielectric constant. Component developers can be used. The one-component developer is obtained by mixing a binder and a pigment or a dye with an oily or aqueous solvent.
An aqueous or oily developer known in, for example, Japanese Unexamined Patent Publication No. 8 can be used. Then, various special agents may be added to the developer as needed to exhibit a special function. As the special agent, for example, an additive for viscosity control, a surface tension modifier that contributes to fixation of the pigment on the transfer paper S, or the like can be used. The viscosity of the one-component developer is desirably 500 cp or less. Also,
It is desirable that the material be non-volatile so that it does not dry and stick at the developer supply port. The one-component developer may be charged or uncharged. Here, as the one-component developer and the two-component developer, both aqueous ink and oil-based ink can be used. However, a material that may damage the surface of the developing roller 131 or the latent image body should not be selected. Examples of the water-based ink include a water-soluble ink mainly composed of water, a lubricant, a dye, water, a pigment, and a dispersion ink. An aqueous pigment-dispersed ink mainly composed of a polymer compound and a lubricant, and an emulsion ink in which a pigment or a dye and a surfactant are dispersed in water are used. As the oil-based ink, for example, as in the case of the aqueous ink, an oil-soluble dye dispersed in an organic liquid compound, or a pigment or dye emulsified in an oil base is used.

The tank 22 has a pump P for pumping the stored developer into the developing container 130 and the like via the developer supply pipe 23, a density sensor 24 for detecting the toner density of the stored developer, and the like. Is provided. Reference numeral 25 denotes a developer discharge pipe for stirring the developer in the tank.

The above configuration is basically the same as that of a conventionally known wet two-component developing device, and develops an electrostatic latent image on the photosensitive drum 10 as follows. First, the tank 22
The developing solution inside is pumped up by the pump P into the developing container 130 via the developing solution supply pipe 23, and is supplied from the discharge port into the developing solution container 131C, where a pool of the developing solution is formed. The developing solution pumped up by the rotation of the developing roller 131 from the pool of the developing solution in the developing solution container 131 </ b> C is conveyed to a developing area, which is an opposing portion between the photosensitive drum 10 and the developing roller 131, and Is supplied to the electrostatic latent image. At this time, the developer carried on the developing roller 131 is squeezed with excess developer by the squeeze roller 131 </ b> Q before facing the photosensitive drum 10.
The thickness of the developing solution is regulated so that the surface of the developing solution and the surface of the photosensitive drum 10 do not come into contact with each other, and thereafter, the developing is performed in a developing region where the developing roller 131 and the photosensitive drum 10 face each other. Excess carrier liquid is squeezed from the developed image in the area of the surface of the photosensitive drum 10 that has passed through the developing area and faces the developing liquid squeeze roller 132. The carrier liquid transferred to the developer squeeze roller 132 by the squeezing is removed by the scraper 132S, and is collected in the tank 22 through the developer collection pipe 21 opened at the bottom of the developing container 130. When the developing solution squeeze roller 132 is made of a conductive material like the developing roller 131, an electric field is formed between the developing solution squeezing roller 132 and the electrostatic image on the photosensitive drum 10 to assist the developing squeeze roller 132. Functions can be exercised.

Incidentally, the wet developing apparatus 1 according to the present embodiment
Reference numeral 3 denotes a developing roller 131 of the wet developing device 13 having a flat surface with no unevenness, forming uniform droplets of the developing solution on the surface, and performing development with the droplets. Hereinafter, this will be described. In the present embodiment, uniform regions of the developing solution are formed on the surface of the developing roller 131 by forming regions having different receding contact angles on the surface of the material constituting the surface of the developing roller 131. here,
When the value of the receding contact angle θr decreases, the value of the frictional tension γf increases, so that the liquid does not easily slide on the solid surface, and the liquid adheres to the solid surface. From this, the liquid adhesion depends on the receding contact angle θr.
The receding contact angle θr is determined by a material having a surface self-orientation function on the surface. Therefore, since the developing roller 131 in this embodiment needs to form a uniform droplet of the developing solution on the surface, at least the surface is made of a material having a surface self-orientation function on the surface. The material having a surface self-orientation function on the surface is a compound containing a molecule having a high self-aggregation property, a molecule having a planar structure, and a linear molecule having a hydrophobic group at a terminal.

Therefore, in the present embodiment, as the material constituting at least the surface of the developing roller 131, a material (A) which is reduced in the receding contact angle when heated and in contact with a liquid is used. As this material (A), for example, there are compounds having the following structure shown in JP-A-3-178478.

Embedded image

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Then, the material (A) is contacted with a contact material (B) selected from a liquid, a vapor, or a solid which generates a liquid or a vapor at a temperature equal to or lower than the temperature at which the receding contact angle of the material (A) starts to decrease. Is selectively heated while in contact with the material, or is brought into contact with the contact material (B) while the surface of the material (A) is partially heated, so that the surface of the material (A) retreats according to the heating temperature. An area indicating a contact angle is formed.

The contact material (B) is a polar liquid such as water, an aqueous solution containing an electrolyte, an alcohol such as ethanol or n-butanol, a polyhydric alcohol such as glycerin or ethylene glycol, or a ketone such as methyl ethyl ketone. And non-polar liquids such as linear hydrocarbons such as n-nanone and n-octane, cyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as m-xylene and benzene. Further, as the contact material (B), a mixture thereof, or various dispersions and liquid inks can be used. More desirably, polar liquids are better.

Next, the heating means will be described. As the heating means, a contact heating means such as a heater or a thermal head, or a non-contact heating means using electromagnetic waves (light from a light emitting source such as a laser light source or an infrared lamp is condensed by a lens) can be employed. In addition, even when electron beam irradiation and light (UV light) irradiation are used, it can be adopted as long as heating is performed substantially. The heating temperature is preferably in the range of 50 to 250C, more preferably 80 to 150C. The heating temperature is about 0.1 msec to 1 sec, preferably 0.5 msec.
sec to 2 msec.

Next, a specific method for manufacturing the developing roller 131 according to this embodiment will be described below. The above material (A)
As a water- and oil-repellent agent “TG-702” or “TG-602” (trade name, manufactured by Daikin Industries, Ltd.), which is a fluorine-containing acrylate material, this undiluted solution is subjected to freon TF (trade name, manufactured by Mitsui Fluorochemicals) 2 After dilution by a factor of 2,
As shown in FIG. 2, coating is performed on the aluminum roller 1,
After drying at 90 ° C. for 2 hours, a film 2 having a thickness of about 1 μm is formed.
Then, in a state where a liquid 3 such as pure water as a contact material (B) is brought into contact with the film 2, a heating section 4 of a thermal head for a thermal transfer printer is brought into contact with the surface of the film 2,
The film 2 is heated by sending an appropriate signal to the thermal head while rotating. By doing so, the developing roller 1
Regions having different receding contact angles can be formed on the surface 31. That is, the receding contact angle in the region heated by the thermal head becomes smaller, and the receding contact angle in the region not heated by the thermal head becomes larger. According to an experiment by the present inventors, as shown in FIG. 3, when the receding contact angle of the surface of the film 2 before heating was 100 °, the receding contact angle after heating by the thermal head was 40 °. Became. On the surface of the developing roller 131 having a partially different receding contact angle formed as described above, the developer adheres in a region where the receding contact angle is 90 ° or less, and the developer adheres in a region where the receding contact angle is 90 ° or more. Since the toner is not repelled and adhered, droplets can be formed on the surface of the developing roller 131 in accordance with the heated area. In this embodiment, by regularly sending a signal to the thermal head to regularly heat the surface of the developing roller 131, a regular developing solution adhering area can be formed on the surface of the developing roller 131. As shown in FIG. 4, the droplets 5 can be regularly adhered to the surface of the developing roller 131.

Here, by changing the heating time by the thermal head, it is possible to change the size of the area on the surface of the developing roller 131 where the droplets adhere (the area where the receding contact angle is small). According to an experiment by the present inventors, for example, a voltage of 10 V was applied to a thermal head having a heating element resistance of 400 dpi at 200 dpi, and the energizing time was set to 1.0.
When msec is set, a droplet adhered area with a diameter of about 100 μm is formed. When the energization time is set to 0.5 msec, the diameter is about 40 μm. When the energization time is set to 0.3 msec, a droplet is set to about 10 μm. Was formed. The area to be heated on the surface of the developing roller 131 is not particularly limited, but it is preferable that the area of the heated part is small and the pitch is small because the resolution is good.

Next, another embodiment in which regions having different receding contact angles are formed on the surface of the developing roller 131 will be described.
As shown in FIG. 5, for example, a metal roller, a resin roller, or a surface of a roller 1a in which a conductive process is performed on the resin roller,
A solution obtained by diluting the fluorine-containing acrylate material as the material (A) with a solvent is partially adhered in an island shape by a printing technique such as screen printing, letterpress, intaglio, pad printing, and the like. 2a is formed. In the present embodiment, in order to change the receding contact angle on the surface of the film 2a at the final stage of the drying step, the entire roller 1a is impregnated with the contact material (B) and heated.

By performing the above, the developing roller 13
On one surface, only the receding contact angle on the surface of the film 2a can be reduced, and the developer can be adhered only on the film 2a. Further, in the above-mentioned drying step, the area of the material to be dried is smaller than that of the uniform single-layer film 2 in the above embodiment, so that the drying step can be completed in a short time.
Manufacturing efficiency can be increased.

FIG. 6 is an explanatory view of a method for forming regions having different receding contact angles on the surface of the developing roller 131 according to another embodiment. In this embodiment, irregularities are formed on the surface of the roller 1b, and the material (A) is uniformly applied to the entire surface and dried (see FIG. 6A). Thereafter, the convex portion 100 is mechanically polished or subjected to a chemical treatment.
The surface is exposed, and a film 2b is formed on the surface of the roller 1b (see FIG. 6B). Then, the entire roller 1b is impregnated with the contact material (B) and heated.

In the manner described above, only the receding contact angle on the surface of the film 2b formed in an island shape on the surface of the roller 1b can be reduced, and the developing solution can be adhered only on the film 2b. it can.

In this embodiment, if the material (A) is filled only in the concave portion on the surface of the roller 1b,
The treatment of impregnating and heating the dried contact material (B) can be performed without the need for the above-mentioned treatment such as polishing.

The developing roller 131 manufactured by the method described in the above embodiment has the following characteristics, and can sufficiently withstand practical use as a developer carrier of a wet developing device. The first characteristic is that the material (A) provided with a property having a different receding contact angle maintains its property unless the surface property is modified or the material is not heated again without the contact material (B). It is. The second characteristic is that the material (A) to which the property in which the receding contact angle is once different is given,
Even if the contact material (B) is simply brought into contact, its properties are maintained unless it is heated in that state. Of course, the contact material (B)
That is, even if it comes into contact with other materials, its characteristics are maintained.

The film (2, 2) on the surface of the developing roller 131 made of the material (A) formed as described above
a, 2b) can exhibit characteristics in which the receding contact angle changes from a thickness of several tens angstroms. However, in consideration of the surface properties of the material of the developing roller 131 and its use as a developing roller, a thickness of several μm to 30 μm is desirable. Further, the manufacturing method shown in the above embodiment is
The present invention can also be applied to a belt-shaped developer carrying member instead of a roller as in the above embodiment.

Next, a developing method using the developing roller 131 will be described. In the following description, the developing roller having the configuration shown in FIG. 4 will be described as an example.

In FIG. 7, the developing roller 1 is arranged so that a part thereof is immersed in the developing solution in the developing solution container 131C.
Numeral 31 rotates at the speed of Vd in the arrow direction. Further, the photosensitive drum 10 arranged with a gap A with respect to the developing roller 131 is rotating in the direction of the arrow at the speed of Vp. Further, a predetermined voltage is applied to the developing roller 131 and the photosensitive drum 10 by the power supply 70 so that a predetermined electric field is formed between the developing roller 131 and the photosensitive drum 10. In this figure, when the developing roller 131 rotates, the developer container 131 is rotated.
The developer in C is held in the form of droplets on the surface (see FIG. 4), and is conveyed to a region facing the photosensitive drum 10. Here, the electric charge is injected into the droplet 5 on the surface of the developing roller 131 by the power supply 70, so that the droplet 5 is easily attached to the electrostatic latent image.
The droplet 5 on the surface of the developing roller 131 in the facing region is
The electric field generated by the power supply 70 flies through the gap A, adheres to the electrostatic latent image formed on the surface of the photosensitive drum 10, and is used for development.

In this embodiment, as the voltage, for example, an AC, a DC, or a power supply having an AC component and a DC component may be selected from a combination in which the droplet 5 can easily fly. When the rotation speed Vd of the developing roller 131 and the rotation speed Vp of the photosensitive drum 10 are Vd / Vp = 1, the droplet 5 on the surface of the developing roller 131 moves at a constant speed.
Adheres to the surface of the photosensitive drum 10. Then, the droplets 5 deposited on the photosensitive drum 10 are finally transferred to the transfer paper S. At this time, if the concentration of the developer attached to the photosensitive drum 10 is low, the rotation speed of Vd / Vp By increasing the ratio, the amount of the developer adhering to the photosensitive drum 10 can be increased. Furthermore, by increasing the rotation speed ratio of Vd / Vp, jaggies (jaggies) that are likely to occur when developing oblique lines can be reduced, and a smooth curve can be obtained.

FIG. 8 is an explanatory diagram of a developing method according to another embodiment. This embodiment is significantly different from the above embodiment in that the transfer sheet S is opposed to the developing roller 131 in a non-contact manner. On the back surface of the transfer paper S, a plurality of electrodes 80 such as, for example, matrix electrodes are disposed in close contact with the transfer paper S. Further, a pulse-like voltage is applied to the electrode 80 and the developing roller 131 by the power supply 81, and an electrostatic force is generated therebetween. In the above configuration, the developing roller 131 conveyed to the area facing the photosensitive drum 10 in the same manner as in FIG.
The upper droplet 5 is supplied to the developing roller 13 by electrostatic force from a power source 81.
1 flies through the gap between the transfer paper 1 and the transfer paper S, adheres to the transfer paper S, and is subjected to development.

As described above, according to the present embodiment, the developing roller 131 having no unevenness on the surface can be used. Therefore, it is possible to reduce the cost without requiring the trouble of the concavo-convex processing unlike the related art. Further, when the developing solution fills the space between the developing roller 131 and the photosensitive drum 10 only in the image, the fine particle toner migrates in the carrier liquid between the developing roller 131 and the photosensitive drum 10 and finely Since the latent image is developed, a high-resolution image is obtained. Further, since the toner as a colorant does not directly adhere to the photosensitive drum 10 and the toner containing the colorant migrates to the latent image via the carrier in the developer, the developer protrudes from the latent image and adheres. However, only the latent image portion is developed. Further, since the developing roller 131 and the photosensitive drum 10 do not come into contact with each other, both may be rigid bodies, and there is no need to strictly control contact with each other.

In this embodiment, it is also possible to use the one-component developer described above (in this case, the developer squeeze roller 132 is not necessarily required).

[0044]

According to the first to third aspects of the present invention, since the adhesion of the developer to the latent image is governed by the one-component developing method, the developer selectively adheres to the image portion of the latent image, It does not adhere to the non-image portion of the latent image. For this reason, the non-image portion does not get wet with the developing solution, there is no background stain, the consumption of the developing solution is small, and the amount of heat for evaporating the excess developing solution is not required. In addition, since a developer carrier that does not require any special processing on the surface is used, labor and cost for the processing can be saved. further,
As described above, the developer carrying member does not require any special irregularity processing on the surface, and there is no strict restriction on the surface shape. Therefore, the developer carrying member having various irregularities and pitches can be used. In addition, since the developer adheres or does not adhere due to the receding contact angle on the surface of the developer carrier, if the region having a uniform receding contact angle is formed on the surface of the developer carrier, the developer can be developed. It can be uniformly attached to the surface of the liquid carrier. Further, since the amount of the developer on the surface of the developer carrier can be regulated so as not to fill the gap between the developer carrier and the latent image carrier, strict developer regulation conditions are not required.

In particular, according to the first aspect of the present invention, since the surface of the developer carrying member is made of a material whose receding contact angle is reduced when the developer carrying member is brought into contact with the liquid in a heated state, a desired region can be formed. By heating and contacting with the liquid, there is an effect that only the receding contact angle of the area is reduced and the developer can be attached. According to the second aspect of the present invention, the surface of the developer carrying member is made of a material having a reduced receding contact angle when heated and in contact with a liquid, and a heated region and a non-heated region are formed. The contact angle of the heated region by contact with a contact material selected from liquid, vapor, or a solid that generates liquid or vapor at or below the temperature at which the receding contact angle of the material decreases. And the developer can be made to adhere to the developing solution. According to the third aspect of the present invention, the receding contact angle of the surface of the developer carrying member is reduced when the surface of the developing solution carrier is in contact with the liquid in a heated state, and the heated region is partially formed of an island-like material. It is not necessary to selectively heat the developer carrier surface,
Further, there is an effect that the receding contact angle of the surface of the developer carrier can be partially reduced only by bringing the entire surface into contact with the contact material .

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an electrophotographic copying machine according to an embodiment.

FIG. 2 is an explanatory diagram illustrating a specific method for manufacturing a developing roller according to the embodiment.

FIG. 3 is an explanatory diagram showing changes in receding contact angles before and after heating.

4A is an explanatory diagram showing a state in which droplets adhere to the surface of the developing roller, and FIG. 4B is a partial cross-sectional view of the surface of the developing roller shown in FIG.

FIG. 5 is an explanatory view showing a method of manufacturing a developing roller surface according to another embodiment.

6A is an explanatory view showing a state in which a material (A) is applied to the surface of a developing roller in a method of manufacturing a surface of a developing roller according to another embodiment, and FIG. 6B is a diagram showing the surface of the developing roller shown in FIG. Explanatory drawing which shows the state after processing.

FIG. 7 is an explanatory diagram illustrating a developing method using a developing roller according to the embodiment.

FIG. 8 is an explanatory view showing a developing method according to another embodiment.

FIG. 9 is an explanatory view of a conventional developing roller surface shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum roller 2 Film 3 Liquid 4 Heating part 5 Droplet 131 Developing roller

Continuation of the front page (56) References JP-A-3-55583 (JP, A) JP-A-4-17477 (JP, A) JP-A-2-56585 (JP, A) JP-A-1-237581 (JP) , A) "Plastic Dictionary", edited by the Plastic Dictionary Editor's Committee, published by the Industrial Research Institute, p. 177 "contact angle contact angle" (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/10

Claims (3)

(57) [Claims] 1. A developing device for developing a latent image on a latent image carrier using a liquid developer, wherein the developing device is disposed to face the latent image carrier and carries the developer. In the liquid carrier, the surface of the developer carrier is made of a material having a reduced receding contact angle when heated and in contact with a liquid, and
By partially heating the liquid in contact with the liquid or by contacting the liquid with the liquid in a partially heated state, an area showing a receding contact angle according to the heating temperature is formed on the surface. Developer carrier. 2. A wet developing apparatus for developing a latent image on a latent image carrier using a liquid developer, wherein a surface of the latent image carrier is made of a material having a reduced receding contact angle when heated and brought into contact with a liquid. A heated region and a non-heated region are formed on the surface, and the surface and the liquid or vapor are selected from a liquid or a solid that generates a liquid or vapor at a temperature equal to or lower than a temperature at which the receding contact angle of the material starts to decrease. A developing solution carrier having a region having a receding contact angle corresponding to a heating temperature formed on the surface by contacting the contact material; and a developing solution supply unit for attaching the developing solution to the heating region. A wet type developing device characterized by the above-mentioned. 3. A wet developing device for developing a latent image on a latent image carrier using a liquid developer, wherein the region heated in a heated state and whose receding contact angle is reduced when the material is brought into contact with a liquid. Wherein the surface is partially constituted by the material, and the surface is in contact with a liquid or vapor, or a solid selected from liquid or vapor or liquid or vapor at a temperature at which the receding contact angle of the material begins to decrease. A developing solution carrier having a region having a receding contact angle corresponding to a heating temperature formed on the surface by contacting the material; and a developing solution supply unit for attaching the developing solution to the heating region. A wet developing device.