JP3127928B2 - Developing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a developing method and an apparatus used in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like.

[0002]

[Prior art]

Conventionally, dry development methods and wet development methods are generally known as this type of development method. The wet developing method using a liquid developer has an advantage that high resolution can be obtained due to the finer toner particles compared to the dry developing method. However, the liquid developer used in conventional plate development and roller development is inconvenient to handle in many cases, such as leakage of the liquid when the machine is tilted. Therefore, a developing agent which is solid at room temperature and becomes a liquid or a gel by heat or electric stimulation has been developed. One of them is a solid in which colorant particles are dispersed in an electrically insulating organic material at room temperature.Using a developer that reversibly repeats heat melting and cooling and solidification, it is heated by a heating means provided at the bottom of the development tank. Has been proposed (see JP-A-2-81073 and JP-A-2-113275).

[0003]

[Problems to be solved by the invention]

However, in the above-mentioned prior art, the developer is always in a molten state in the tank, and is in a solid state when the power is off for a long time, for example, only at night or on holidays. In this case, the merit of the reversibility of the solid liquid is limited only when the developer is solidified in advance such as when the machine is moved, and is not fully utilized. Further, in the above-mentioned conventional technique, in a liquefied state, development is performed by a normal wet two-component development method (also referred to as electrophoresis development method), and charged toner particles are suspended in an insulating organic solvent. Then, development is performed by an electric field formed between the electrostatic latent image formed on the photoconductor and the developing electrode. The developer used for this consists of two components, toner and an insulating organic solvent, and the insulating organic solvent requires several tens of times the amount of the toner. When a developer is used, a large amount of a solid developer is required, and replacement of the developer becomes frequent. Therefore, there arises a problem that a large space for storing the developer is required. Furthermore, once the developer is liquefied, the ratio between the toner and the insulating organic solvent changes after the developer is used for development, so that the developer cannot be reused as it is. If the toner and the insulating organic solvent are separate replenishing means, they can be reused by replenishing only the insulating organic solvent, but in this case the two components are mixed and the remaining developer is reused. There is no way to do that.
Therefore, the liquid developer remaining on the photoreceptor must be cleaned and collected by a cleaning means such as a blade, which is not only one of the causes that requires a large amount of the developer, Both the toner remaining on the photoreceptor after development and the insulating organic solvent are discarded, resulting in high costs and waste. Further, the ratio between the toner and the insulating organic solvent may be changed due to evaporation of the insulating organic solvent from the developing roller or the surface of the photoreceptor, and the image quality is degraded. The present invention has been made in view of such problems of the related art, and a first object of the present invention is to use a solid liquid reversible developer and to exist as a solid in a normal state. By providing a development method that liquefies only at the time of development and that the developer is not always stored in the machine in a liquid state and the developer does not spill out even when the machine is tilted unintentionally. A second object of the present invention is to provide a wet developing method in which the developer does not spill when the wet copying machine is moved or when the developer is replenished, and is wasteful.

[0004]

[Means for Solving the Problems]

In order to achieve the first object, the invention according to claim 1 is characterized in that it is solid at ordinary temperature and has the reversibility of melting and solidification which is melted by heat, and substantially in a molten state in a molten liquid by an electric field. A solid-state developer capable of wet one-component development without particle movement is locally heated and melted by a heating and melting member disposed near the opening of the developing container, and brought into contact with the electrostatic latent image;
The electrostatic latent image is subjected to wet one-component development. To achieve the second object, the invention according to claim 3 is directed to a crystalline polymer having a long alkyl group and a colorant. Containing a dispersant and a conductivity adjusting agent, is solid at room temperature, has the reversibility of melting and solidifying due to heat, and is wet in a molten state substantially without particle movement in a molten liquid by an electric field in a molten state. It is characterized in that a developer capable of one-component development is melted by heating during development, brought into contact with an electrostatic latent image, and the electrostatic latent image is subjected to wet one-component development. [Function] The invention according to claim 1 is a method in which a solid developer which is solid in a normal state and is melted by heat and has reversibility of melting and solidification is locally heated and melted by a heating and melting member arranged near an opening of a developing container. In this case, the developer is heated and melted, and the developer is liquefied by the amount required for the development just before the development so that the developer can be developed.
In addition, during development, the entire liquid behaves as a toner when it is melted by heat, and only the toner particles are selectively used, as in the wet two-component development method, causing a change in composition and a corresponding change in toner charge. However, it works so that the electrostatic latent image can be developed. According to a third aspect of the present invention, during development, the entire liquid behaves as a toner in a state of being melted by heat, and only the toner particles are selectively used as in a wet two-component development method to change the composition and the resulting toner. The electrostatic latent image acts so that the electrostatic latent image can be developed without causing a charge change.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment in which the present invention is applied to an electrophotographic copying machine as an image forming apparatus will be described. In FIG. 1, according to a well-known electrophotographic process, a photosensitive member 1 is charged, and reflected light from a document is image-formed by an optical system (not shown) to form an electrostatic latent image. The developer is supplied to perform development. The developed electrostatic latent image is transferred to a transfer material by a bias to be a visible image. There is no fixing step because fixing is only based on penetration of the developer into the paper. The developer is non-volatile and does not need to be dried. This is an example of the roller developing method, in which the developer 2 in the developer container 4 is solid in a normal state, and the leading end thereof is a developing electrode arranged so as to close the opening of the developer container 4. By contacting the developing roller 7 having a certain heat source 6,
It melts locally and becomes liquid. The developer that has become a liquid is supplied to the photosensitive member 1 by the developing roller 7 as in the conventional roller development.
To develop the electrostatic latent image. The developer 2 is constantly pressed against the developing roller 7 by the pushing member 3.

FIG. 2 shows an example in which the photosensitive member is transported linearly. As in the example shown in FIG. 1, the developer 2 in the developer accommodating case 4 is solid in a normal state and the developer is extruded. By being pressed against the upper lid having the heat source 5 by the member 3, the liquid locally melts and becomes a liquid, flows out of a slit formed by the upper lid having the heat source 5, and forms an electrostatic latent image formed on the photoconductor 1. develop.

The developer extruding member 3 used in each of the above embodiments is not shown, but is composed of a spring, a screw, an eccentric cam, or the like, and the extruded developer generates heat from the heat sources 5 and 6. Therefore, even if the volume is reduced, the developer is constantly pressed against the developing roller 7 and the developer accommodating case 4 so as to be in contact with the upper lid.

FIG. 4 shows a cross section of the solid developer in each of the above-mentioned embodiments. A plate-like member 13 made of a heat-insulating material such as plastic is fixed to a surface of the solid developer in contact with the extruding member 3. Have been. Until it is stored in the developer storage case 4, it is wrapped in the developer cover 15.

FIG. 3 shows a cross section of the bottom of the developer case 4. The plate-like member 13 has a guide groove 14, and a projection 16 provided on the pushing member 3 in the developer case 4. It is designed to interact with them. The developer 2 wrapped in the developer cover 15 is inserted into the developer case 4 along the protrusion 16 attached to the extruding member 3, and after the insertion, the developer cover 15 is pulled out and used.
The developer is extruded together with the plate member 13 by the extruding member 3. When the developer runs out, insert a new solid developer. Since the replaceable solid developer liquefies at a temperature higher than the melting point, the storage temperature must be lower than the melting point. Since the photoreceptor 1 is also heated by the heat source 10, the liquefied developer 2 remains liquid both when the electrostatic latent image is formed and when the image is transferred from the photoreceptor to the transfer target. As usual, the toner migrates through the insulating organic solvent.

Next, a developer for performing wet one-component development in a state of being heated and melted will be described. In the wet one-component developing method, a coloring material is dispersed or dissolved in a liquid, but the coloring material in the liquid does not move and the whole liquid acts as a toner. Such a behavior in a liquid state, and as a solid developer at normal temperature, organic substances, colored particles, consisting of resins,
It has a relatively low resistance as a whole. As organic substances, plant waxes such as carnauba wax (mp83-93 ° C), candelilla wax (mp67-72 ° C), animal wax such as beeswax (mp61-65 ° C), insect wax (mp65-80 ° C), paraffin wax, micro There are petroleum waxes such as crystallin wax, mineral waxes such as ozokerite and montan wax, and paraffins having 19 to 60 carbon atoms.
The melting point of these organic substances is 50 ° C. or higher. This is because the temperature around the developing device is higher than room temperature and is solid at normal temperature. Even if the organic substance itself is an insulator, it is sufficient that the overall resistance of the developer is relatively low by a conductivity adjusting agent described later, but the organic substance itself is preferably as low as possible.

In this organic substance, an organic pigment, an inorganic pigment,
Resins such as synthetic resins, natural resins, and rubbers are used to disperse dyes and the like and improve the dispersibility, stability, fixability, and the like. In addition, a quaternary ammonium salt, a low-molecular-weight fluorine-containing resin or a low-molecular silicone for preventing the flow of an image is added as a conductivity adjusting agent.

FIG. 5 shows an example of the roller developing method. The difference from the apparatus shown in FIG.
The surface of the developing roller 7 is provided with a groove, and the surface of the developing roller 7 is provided with an appropriate elasticity to prevent damage to the drum surface and promote uniform contact with the drum.
The point 17 is always in pressure contact.

A heat source 6 is built in, and the solid developer 2 is constantly pressed against the surface of the developing roller 7 at normal temperature, and the solid developer 2 in the pressed portion is locally melted and liquefied. . The developing roller 7 has a function of keeping the temperature of the liquid developer constant, and controlling the temperature of the developer helps stabilize the viscosity of the developer, which is an important characteristic of the developing system. The developing roller 7 has a solid developer 2 and a doctor blade.
17 is always in pressure contact, and the amount of developer in the groove portion is always kept constant by the rotation of the contact with the photosensitive drum 1 and used for development. The doctor blade 17 also has a function of removing the developer at the top portion and preventing the developer from adhering to the non-image portion. The developer held in the groove is induced to have an opposite polarity charge by the latent image charge, and is attracted to the latent image charge via the apex portion by an electric capillary phenomenon and developed.

Since the photoconductor 1 is also heated by the heat source 10, the liquefied developer 2 remains in a liquid state even when developing the electrostatic latent image and when transferring from the photoconductor to the transfer target. The viscosity of the developer is also a value suitable for development transfer.

Since the developer that performs wet one-component development in a molten liquid state is relatively conductive, if the developer remains on the photosensitive member after the transfer of the electrostatic latent image, charge leakage or leakage occurs. Latent image blur occurs and the next cycle is not established. Therefore, thorough cleaning is required. In the cleaning, the developer collected using a blade is considered to contain foreign matter such as paper dust, and when collected and reused, there is a concern that the grooves on the surface of the developing roller may be clogged.

The charge removing step is unnecessary because the developer is conductive, so that the charge is removed almost at the same time as the development, or even if there is a residual latent image due to poor development, because the developer contacts the cleaning section.

FIG. 6 shows the case of linear conveyance of the photoconductor, corresponding to the example of FIG. The difference from the example of FIG. 2 is that instead of the opening on the slit,
The point is that a relatively wide opening is provided, and a heat conductive mesh 18 in contact with the heating means 5 is provided in this opening to constitute an upper lid. The leading end of the developer is pressed into contact with the mesh 18 by the developer pushing member 3 to be melted into a liquid, thereby developing the electrostatic latent image formed on the photoconductor 1. Alternatively, it is pressed into contact with an upper lid 19 formed of a mesh having a heat source itself to melt and become a liquid, thereby developing the electrostatic latent image formed on the photoconductor 1 (see FIG. 7).

In the development in the case of the mesh, the overlapping portion of the mesh corresponds to the vertex of the roller of the first embodiment, and the developer existing in the gap of the mesh induces the opposite polarity charge by the latent image charge, and the electric capillary phenomenon causes the developer. The latent image charge is attracted to the latent image via the top of the mesh.

A method as shown in FIG. 8 can also be used. In this method, the developer melted and liquefied by the developer supply roller 24 having a heat source is transported to the photoconductor by the mesh belt 20. The mesh belt 20 is supported by two or more rollers and can move between the developer supply unit 21 and the photosensitive member 1.
The roller 22 is pressed against the mesh belt 20 and is supported by one or more rollers 23. Development is the sixth
This is the same as the case of the mesh of the embodiment shown in FIGS.

The solid developer 2 is melted by a developer supply roller 24 having a heat source, and the rotation of the roller causes a mesh belt disposed so as to be in contact with the developer with the developer supply roller 24 interposed therebetween. It is supplied and held in the 20 recesses and used for development. The mesh belt 20 is sandwiched between the squeeze rollers 25 facing the developer supply roller 24, and excess developer attached to the projections and the like is squeezed.

As a method of transporting the developer melted and liquefied by the developer supply roller 21 having a heat source to the photosensitive member by the mesh belt 20, there is a method as shown in FIG. In this case, it is supported by at least a roller 22 for pressing the mesh belt 20 against the photoreceptor 1 and a roller 24 having a heat source and melting the solid developer. That is, the roller 24 has a function of melting and liquefying the solid developer and a function of carrying the developer to the photoconductor and supporting the mesh belt 20 used for development. Thereby, the number of mesh belt supporting rollers can be reduced, which contributes to cost saving.

The developer supply roller 24 having a heat source is connected to the mesh belt 20.
The solid developer is melted and liquefied through the liquefied developer, and the liquefied developer is meshed by a mesh belt supported by a developer supply roller 24.
It is held and carried in the 20 recesses.

Excess developer adhering to the convex portions and the like is removed by two squeeze rollers so as to sandwich the mesh belt 20 between the developer supply roller 24 and the roller 22 for pressing the mesh belt 20 against the photosensitive member. Set 25 and squeeze.

As shown in FIG. 10, the mesh belt 20 can be supported by a roller 22 and a squeeze roller 25 for pressing against the photosensitive member. One end of the mesh belt 20 supported by the squeeze roller 25 is disposed in contact with the surface of the developer supply roller 24 having a heat source opposite to the surface in contact with the solid developer. The solid developer 2 is melted and liquefied by a developer supply roller 24, and the squeeze roller is rotated by rotation of the roller.
It is supplied to a mesh belt 20 supported by 25.
At the same time, excess developer adhering to the convex portions of the mesh belt 20 is removed by the squeeze roller 25 and the developer supply roller.
The developer is squeezed by a squeeze roller 25 arranged so as to sandwich the mesh belt 20 with the developer 24, and the developer held in the concave portion is carried to the photoconductor 1 and developed. In this example, the number of squeeze rollers can be reduced, which is advantageous in layout and cost saving.

As a developer regulating method when the mesh belt 20 is supported by at least a roller 22 for pressing the photosensitive member 1 and a developer supply roller 24, as shown in FIG. A squeeze roller 25 may be provided in contact with the developer supply roller 24 and also in contact with the surface of the developer 2. Since the squeeze roller 25 also serves as a mesh belt support roller, the number of components is small, and the squeeze roller 25 is in contact with the surface of the developer, so that the squeezed liquid developer returns to the developer case 4 and can be reused.

Although the developer extruding member 3 used in each of the above-described embodiments is not shown, similar to those shown in FIG. 1, FIG. 2, and FIG. 5 to FIG. It is constituted by an eccentric cam or the like, and is pressed so as to be always in contact with the developer melting member even if the extruded developer is melted and reduced. Further, in order to improve the conversion property of the developer, a structure similar to that shown in FIGS. 1 to 4 can be employed.

[0027]

【The invention's effect】

In the present invention, unlike the case of the conventional wet development, the developer is usually in a solid state and is liquefied by a necessary amount at the time of development, so that there is no excess liquid in the copying machine. Therefore, there is no fear of liquid leakage even when the machine is tilted, for example, when transporting the machine, and work around the developing device is easy during maintenance. For example, in the case of slit development, since a heating means is attached to the member forming the slit, it is pressed and melted by the extruding member, and comes out of the slit immediately after being melted by being pushed by the extruding member. No developer is present. Also, for example, in the case of roller development, since the developing roller is provided with a heating means, the developer melted by the amount in contact with the developing roller and the liquefied developer on the surface of the developing roller remains on the photosensitive member by the developing roller. As it is carried, there is no excess liquid developer. Further, even when the solid developer is melted and reduced, for example, if the developer extruding means is provided on the side opposite to the heat melting part, the developer is always pressed against the heating means, so that the supply of the developer is always performed. It will not be interrupted. Regarding the handling of the developer, the liquid developer replenishment method currently used, whether it is the chicken feed method or the pressure can method, is a cartridge type, but if it falls, the liquid is supplied from the supply port. Blowing out and spilling are inevitable. In the case of two-component development, replenishment of an insulating organic solvent is also necessary. If this also spills out, unpleasant odor and feeling are not good. However, if the developer is a solid in a normal state as in the present invention, the developer can be easily handled in terms of storage, transportation, and replenishment without soiling the hands. Since there is no danger of liquid dripping, the layout of the developing unit can be freely adjusted, and the layout of the entire machine is also variable. Further, since the developer is solid in a normal state, only the developer can be replaced when the developer is consumed, and the cost is lower than when, for example, the entire developer case is replaced. If you replace the developer along the guide rail,
Work becomes easier. If the replacement is performed while being wrapped in the cover and the cover is removed after insertion, the replacement operation can be performed without damaging the hands. In a state where the developer is melted, wet one-component development is performed, and
Unlike the component-based developer, a non-volatile wax or the like is used without using an insulating organic solvent, so that no solvent adheres to the background portion, and no drying or fixing of transfer paper is required. No solvent evaporation from the developer adhering to the image area was observed at all. In addition, stable development conditions can be maintained without physical property changes due to spontaneous evaporation from the surface of the developing roller. Since there is no drying or fixing step, there is no need for a fixing heater, and it is possible to save cost, labor, light weight, and quick image formation in terms of energy, structure, process, and the like. The one-component system has a good stability because the whole liquid acts as a toner, and only one toner particle is selectively used as in a two-component system. There is no need to sense or adjust the composition of the developer. In addition, since the development is performed using a conductive developer, a charge elimination step is not required, so that the size of the developing unit can be reduced and the cost can be reduced. In addition, the fact that development using a conductive developer is also independent of the polarity of the photoreceptor, and the negative / positive can be freely controlled by the development potential contrast and bias polarity.
There is also an advantage that the charging polarity of the photoconductor is not selected.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a roller developing system.

FIG. 2 is a front view of the embodiment when the photosensitive member is transported linearly.

FIG. 3 is a sectional view of a bottom portion of the developer accommodating case of the embodiment shown in FIGS. 1 and 2;

FIG. 4 is a sectional view of the developer of the embodiment of FIGS. 1 and 2.

FIG. 5 is a front view showing an embodiment of wet one-component development.

FIG. 6 is a front view showing another embodiment of wet one-component development.

FIG. 7 is a front view showing still another embodiment of wet single-component development.

FIG. 8 is a front view showing still another embodiment of wet single-component development.

FIG. 9 is a front view showing still another embodiment of wet single-component development.

FIG. 10 is a front view showing still another embodiment of wet single-component development.

FIG. 11 is a front view showing still another embodiment of wet single-component development.

[Explanation of symbols]

1 photoconductor, 2 developer, 3 developer extruder,
4 ... developer storage case, 5 ... heating means, 6 ... developing roller heating means, 7 ... developing roller, 18 ... heat conductive mesh, 19 ... mesh, 20 ... mesh belt, 22 ...
... Mesh belt pressure roller, 23 ... Roller, 24 ... Developer supply roller, 25 ... Squeeze roller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 13/08-13/095 G03G 13/10-13/11 G03G 13/08-13/195 G03G 15 / 10-15/11 G03G 9/12

Claims (8)

(57) [Claims] 1. It is solid at room temperature and has the reversibility of melting and solidifying which is melted by heat, and is capable of wet one-component development in a molten state substantially without particle movement in a molten liquid by an electric field. The solid developer is locally heated and melted by a heating and melting member arranged near the opening of the developing container to be brought into contact with the electrostatic latent image, and the electrostatic latent image is subjected to wet single-component development. Development method. 2. It is solid at room temperature and has the reversibility of melting and solidifying to be melted by heat, and is capable of wet one-component development in a molten state substantially without particle movement in a molten liquid by an electric field. The solid developer is attached and detached between a heating and melting member for locally heating and melting the solid developer, which is disposed near the opening of the developing container, and a developer holding member having an extruding means. The solid developer is locally heated and melted by a heating and melting member arranged near the opening of the developing container and brought into contact with the electrostatic latent image, and the electrostatic latent image is subjected to wet one-component development. A developing device. 3. A polymer containing a crystalline polymer having a long alkyl group, a colorant, a dispersant, and an electric conductivity adjuster, which is solid at room temperature, has reversibility of melting and solidifying by melting with heat, and has a molten state. Using a developer capable of performing wet one-component development without substantially moving particles in a molten liquid due to an electric field, during development, the mixture is melted by heating and brought into contact with an electrostatic latent image to form an electrostatic latent image. A developing method, wherein the latent image is subjected to wet single-component development. 4. It contains one or more crystalline polymers having a long alkyl group such as waxes and paraffins, a colorant, a dispersant, and a conductivity modifier, and is solid at room temperature and melts by heat. A heat-melting member that has a reversibility of melt-solidification and locally heat-melts a developer capable of wet-type one-component development without substantially moving particles in a molten liquid by an electric field in a molten state is formed on a surface. A developing method, comprising a concave portion, wherein a developer is held in the concave portion and brought into contact with an electrostatic latent image, and the electrostatic latent image is subjected to wet single-component development. 5. It contains one or more crystalline polymers having a long alkyl group such as waxes and paraffins, a colorant, a dispersant and a conductivity adjuster, and is solid at ordinary temperature and melts by heat. A melting and solidifying reversible developer capable of wet single-component development in a molten state without substantial particle movement in a molten liquid due to an electric field. And developing the electrostatic latent image by wet single-component development. 6. It contains one or more crystalline polymers having a long alkyl group such as waxes and paraffins, a colorant, a dispersant and a conductivity adjuster, and is solid at room temperature and melts by heat. A developer which has reversibility of melt-solidification and which can be subjected to wet-type one-component development without a particle movement in a molten liquid due to an electric field in a molten state; A developing method, comprising squeezing with a regulating member, holding a developer only in a mesh recess, and bringing the developer into contact with an electrostatic latent image, and subjecting the electrostatic latent image to wet single-component development. 7. One or more crystalline polymers having a long alkyl group such as waxes and paraffins, a colorant, a dispersant, and a conductivity modifier, which are solid at room temperature and melted by heat. A heat-melting member that has a belt-supporting function melts and liquefies a developer that has the reversibility of melt-solidification and is capable of wet one-component development without substantially moving particles in a molten liquid due to an electric field in a molten state. And developing the electrostatic latent image by wet single-component development. 8. It contains one or more crystalline polymers having a long alkyl group such as waxes and paraffins, a colorant, a dispersant, and a conductivity adjuster, and is solid at room temperature and melts by heat. A developer regulating roller having a belt support function, which has a reversibility of melt-solidification, and a developer capable of performing wet single-component development substantially without a particle movement in a molten liquid by an electric field in a molten state, Sandwiching the mesh belt with the heating and melting member, bringing the mesh belt-shaped member into contact with the electrostatic latent image while locally heating and melting with the heating and melting member, and wet-component developing the electrostatic latent image. Development method.