JPS61105575A - Developing device - Google Patents

Abstract

PURPOSE:To obtain developed images of high quality which are not changed with time neither environmentally, by providing a drag generating means which generates a drag due to non-electrostatic force in the direction opposite to the flying direction of a developer so that flying of the developer can be controlled. CONSTITUTION:A developer 8 is a conductive toner and is formed into a single developer layer on a developer carrier 5 and is carried to a developing area, and the electric charge having a polarity opposite to that of an electrostatic latent image 2 is induced in this area under an electric field formed between an electrostatic latent image carrier 1 and the developer carrier 5, and the developer 8 is transferred to only an image part to terminate the development. Further, a non-electrostatic developing drag is given in the direction opposite to the direction, in which the developer tries to fly by the induced electric charge, in the developing area for the purpose of controlling the flying of the developer. By this method, the quantity of the electric charge is not varied among individual toner particles and is not varied by secular change, environmental change, or the like, and a required and sufficient quantity of the developer is always transferred, thus preventing the disturbance of developed images, the occurrence of photographic fog, the variance of density, etc. together with the secular change and the environmental change.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a developing device, and particularly to a developing device using a -component developer.

"Prior Art" Conventionally, in fields such as electrophotography and electrostatic recording, it has been widely known that electrostatic latent images are developed using colored fine powder. Among these, in recent years, one-component development methods using a developer that does not use a carrier, a so-called -component developer, have been actively proposed. As a developing method using such a one-component developer, ■
A method in which developer is formed in the form of a spike on a developer carrier and then developed by rubbing the electrostatic latent image (contact development method); These methods can be broadly divided into methods in which an electrostatic latent image is developed by flying or elongating the developer from above the body (non-contact development method).

The first contact development method can be further divided into a conductive toner contact development method and an insulating (high resistance) toner contact development method.

"Problems to be Solved by the Invention" This conductive toner contact developing method is, for example,
As proposed in Japanese Patent No. 4532, a magnetic brush of magnetic conductive toner is formed on a magnetic roll and brought into sliding contact with the electrostatic latent image, and a charge of opposite polarity is applied to the magnetic brush according to the charge of the electrostatic latent image. In this method, development is performed by injecting (inducing) This method has less fog and can perform development faithfully, but since the magnetic brush comes into contact with the photoreceptor, the latent image charge may leaf and development may not be possible, or it may adhere to the photoreceptor. The toner is further rubbed with a magnetic brush,
This method has the disadvantage that the developed image is disturbed.

The insulating toner contact development method is a method in which development is carried out by rubbing a magnetic brush on the photoreceptor with which the toner has been charged in advance through triboelectric charging. This has advantages such as no charge leakage and easy transfer. However, since this method applies a charge to the toner in advance, it is difficult to apply a uniform charge to the toner, and the amount of charge fluctuates over time or due to the influence of temperature and humidity, causing density unevenness and unevenness in the developed image. It has the disadvantage that fogging etc. occur.

Further, as the second non-contact type developing method, for example, Japanese Patent Publication No. 41-9475, Japanese Patent Application No. 1987-109237-109
No. 242, JP-A-49-104639, etc., the electrostatic latent image carrier maintains a minute gap where the developer layer formed on the developer carrier does not come in direct contact with the developer. This is a method in which an electrostatic latent image is developed by flying or elongating a developer that has been given a charge in advance from above a developer carrier.

In this method, unlike the former developing method, the developer does not come into contact with the electrostatic latent image carrier indiscriminately, and the developer flies or extends only in the image area, thereby preventing the fogging phenomenon. It can almost eliminate the occurrence of the problem, and the developer can be sufficiently ejected to the electrostatic latent image area.
Method 7 It is necessary to impart a charge to the developer, and for this purpose, a method of injecting charge with a charge injection electrode, a method of applying triboelectric charges with a triboelectric charging member, etc. have been proposed.

The charge injection method is a method in which a voltage is applied to an electrode provided close to a developer carrier and in contact with the developer to impart a charge to the developer.In many cases, the electrode is attached to the toner layer. It is also used as a thickness control member. This method is
It has the advantage that the structure is simple and that the polarity of the charge that can be applied to the developer can be arbitrarily set by selecting the polarity of the voltage applied to the electrode.

However, it is only the upper layer of the developer layer that can be charged, and in the inner layer, developers of opposite polarity generated by friction between developers are mixed in the developer layer, and this reverse polarity is mixed in the developer layer. Polar developers may fly and adhere to non-image areas, causing fog.Also, developers of different polarities may adhere to each other to form a chain, which is then flown and developed as a chain. There is a problem in that the sharpness of the image becomes worse.

On the other hand, in the frictional charging method using a frictional charging member, etc.,
There have been proposed methods for increasing the triboelectric charging efficiency by using friction between the developer and the developer carrier or by using a separately provided triboelectric charging member.

However, such a developer charging process is affected by various surface changes over time that contribute to charging, such as a decrease in triboelectric charging efficiency due to developer adhering to the charging member, and a decrease in flight rate due to insufficient developer charge. This may cause a decrease in the
Because triboelectric charging efficiency fluctuates significantly due to environmental changes,
This fluctuation has the disadvantage that it becomes difficult to control the phenomenon. Furthermore, since the developers are also triboelectrically charged, opposite polarity developers exist in the developer layer, which appears as defects in image quality as described above. Furthermore, since the amount of charge of each developer particle contributes to development, a certain amount of charge must be imparted to each developer particle, but since the charge injection probability and contact probability of developer particles differ, There is a problem in that the charge amount of the particles varies, and when development is performed with such a developer, image quality defects such as uneven development occur.

As a result of research on such conventional one-component development methods, the present inventors found that the following drawbacks of the conventional method are: (1) There is variation in the amount of charge on each side of the toner particles, and (2) The amount of charge on each side of the toner particles varies over time. It was found that this is due to the following: - The number of toner particles transferred to the latent image surface is not constant when the toner particles are transferred to the latent image surface.

The present invention was made based on this elucidation result,
There is no variation in the amount of charge on each side of the toner particles, and it does not change with time or environment, etc., and it is possible to transfer a constant number of toner particles at all times.As a result, in the conventional one-component development method, It is an object of the present invention to provide a developing device which can prevent various drawbacks such as disturbances in developed images, uneven density due to fogging, and fluctuations thereof over time and fluctuations due to environment.

"Means and effects for solving the problems" The present invention relates to a developing device, and particularly to a novel developing device using a component developer, and is used to develop an electrostatic latent image carrier or an electrode. A conductive developer is held in a substantially single layer on the agent carrier, and then this developer is transported to a development area so as not to be in contact with the electrostatic latent image carrier or the electrode, and the electrostatic latent image is carried. An electrostatic latent image or a charge of the opposite polarity to the voltage applied to the electrode is induced in the developer in an electric field formed by the body or the electrode and the developer carrier, and the developer is caused to fly only in the image area.
The developing device is characterized in that it is provided with a drag force generating means for generating a drag force by a non-electrostatic force in a direction opposite to the flying direction so as to control the flying of the developer in the developing area. .

"Example" Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a developing device according to an embodiment of the present invention.

In FIG. 1, an electrostatic latent image 2 is formed on a latent image carrier 1 by means not shown, while a developer 8 is held in a substantially single layer on a developer carrier 5 for development. transported to the area.

In the development area, the space between the latent image carrier 1 and the developer carrier 5 is such that the developer layer 4 formed on the developer carrier 5 is out of contact with the latent image carrier 1. The developing agent is transferred only to the image area and the developing action is performed.

More specifically, the developer 8 in the present invention is a conductive toner, is formed into a single developer layer on the developer carrier 5, and is conveyed to the development area, where it is static. Under the electric field formed between the electrostatic latent image carrier 1 and the developer carrier 5, charges of opposite polarity to the electrostatic latent image 2 are induced, and as a result, the developer 8 is applied only to the image area. Transfer occurs and the development process is completed. In addition, the code|symbol 3 is a developing image, 6 is a developer holding member, and 7 is a development bias.

Further, in the developing area, in order to control the flying of the developer, the developing area is made non-static by a method described later in the opposite direction to the direction in which the developer tends to fly due to the induced charge. Electrical development resistance is provided.

Note that the latent image forming method is not limited to a normal electrophotographic method, and can be implemented by any means, such as a method using electrostatic induction using a multi-stylus.

Further, the latent image carrier 1 is not limited to a photoconductor, and may be made of, for example, a dielectric material.

According to the method with such a configuration, there is no variation in the amount of charge between the toner particles as described above, and there is no change over time.
The amount of charge does not fluctuate due to environmental changes, etc., and therefore, it is possible to transfer a sufficient amount of developer at all times. Therefore, various drawbacks of conventional one-component development methods, such as disturbances in developed images, occurrence of fog, density unevenness, etc., as well as changes over time and in the environment can be prevented.

Next, development resistance will be explained. In the present invention, the electric charge held by the toner is determined by the developing electric field, which is equivalent to the conventional force for flying a pre-charged toner to F = Q-E n Fa
d (Q: toner charge amount, ED: developing electric field, Fad;
In the case of the present invention, Q is E゜. The development drag force Fad, which is a function of F'' and can control the flight of toner, is given by a non-electrostatic force, and is characterized by being expressed as F''Q(Ee)'EoFad.

In such a case, the developer is held on the developer carrier in the non-development area by a force expressed as F=-Fad<0,
By transporting the developer to the development area, F = Q (E
ll )・En Fad > 0,
Development is performed by changing the force applied to the developer.

In such a case, by appropriately applying F'ad, it is possible to develop only the desired latent image potential area. In other words, in a region where the force F is negative, the developer does not fly.

The important point is that in the present invention, since the toner charge required for development is not artificially provided using a charging member, etc., the number of control factors can be reduced by one, and the control of flight can be reduced by one. Since the method uses a non-electrostatic force as a development drag force, there is no density unevenness due to variations in Q or density fluctuations due to changes in Q over time, etc., and it is possible to obtain developed images that are faithful to the latent image.

Next, this development resistance will be explained in more detail using FIGS. 2 to 5.

FIG. 2 shows an example in which the developer carrier 5 is composed of a conductive substrate 10 and an adhesive layer 9, and is made of aluminum, iron, SUS, etc.
A pressure-sensitive adhesive such as a rubber elastomer or rosin is applied on a metal such as a rubber elastomer or a resin such as polyvinyl chloride or PET in which fine particles of the metal or conductive particles such as carbon are dispersed. It can be manufactured by coating or laminating.

FIG. 3 shows a mesh "21° 1f" as the developer carrier 5.
9'4T;jo')'m['J°2''''' By holding the film in such a way that it is embedded in 1, an appropriate development resistance can be provided.

FIG. 4 shows an example in which a recessed portion in which the developer is buried is formed on the surface of the developer carrier 5 instead of a mesh. For example, in the case of Fig. 4, sintered nylon, cellulose,
It can be formed by using a porous material such as a hardened spherical resin (trade name: Paper Cone).

In FIG. 5, the surface of the developer carrier 5 is treated with minute irregularities. The fine irregularities as shown in FIG. 5 can be formed, for example, by roughening the surface of aluminum or the like with sandpaper, or by performing a process such as sandblasting or shotblasting.

In this way, forces such as adhesive force, frictional force, van der Waals force, and dispersion force are used as non-electrostatic development drag force, and for example, the material of the developer carrier itself and the material of the developer itself are used. It is sufficient to simply select the desired amount, and sufficient development resistance can be provided without making any special efforts to the shape of the surface of the developer carrier.

Note that this drag force does not include not only electrostatic force but also magnetic force, and is non-magnetic.

In either case, it is important to arbitrarily set a sufficient development resistance to control the flying of the developer.

In any case, as a developer carrier, for example, A6
, a metal such as Fe1NISSOS, a conductive member in place of these, a conductive member coated with a semiconductor or an insulator, or a conductive member embedded in an insulator provided on a conductive member, etc. In short, the member may have various shapes as long as it is capable of supporting the developer. Note that the structure is not limited to the above structure.

Further, as described above, the shape may be a belt shape, a cylindrical shape, or the like.

For example, FIG. 6 shows an example of the developer carrier 5. As shown in FIG.

FIG. 6(a) shows a columnar or cylindrical support for the conductor 10, FIG. 6(b) shows an example in which a protective layer 12 of a semiconductor layer or an insulator is provided on the conductor 10, and FIG. 6(c) shows a protective layer on the conductor 10. An example in which conductive fine particles 13 are dispersed in a layer 12, and (d) an example in which microelectrodes 14 are embedded in a laminated member on a conductor 10 are shown.

The developer used in such a configuration is a conductive developer and has a volume resistivity of 10"Ω or less,
Coloring materials such as pigments or dyes are added to resins, such as polymers and copolymers such as polyvinyl chloride polystyrene, polyethylene, polypropylene, phenol resins, and epoxy resins, alone or in combination, to make them conductive. As the conductive particles, an arbitrary amount of metal or magnetic particles such as magnetite, carbon black, or the like can be added, thereby making it possible to obtain a conductive toner having an arbitrary volume resistivity.

In addition, by setting the developing electric field to several hundred V/tm or more,
The surface potential of the latent image on the latent image carrier and the development bias must be set.
Alternatively, it may be one in which AC is superimposed on DC.

As mentioned above, the present invention is not limited to the development of ordinary electrophotography or electrostatic recording, but can also be applied to, for example, methods such as contrastography or modified electrophotography using intermediates. It is possible.

FIG. 7 shows a modification of the present invention, in which numeral 31 is an image signal generating member, 32 is an image signal electrode, and a signal wave voltage corresponding to the image signal is applied to the image signal electrode 32 at the same time. An electric field is formed between the image signal electrode 32 and the developer carrier 5, and the developer has an induced charge due to the mechanism described above, and flies to and adheres to the recording paper 33. The image thus formed becomes a permanent image through a fixing process (not shown). Note that a charge having a polarity opposite to that of the voltage applied to the electrode 32 is induced in the developer.

FIG. 8 is a diagram showing still another modification, in which an electrostatic latent image is applied to the latent image carrier 1 by a method not shown, for example, by a multi-stylus or the like. In the development area, an intermediate transfer member 34 is disposed between the latent image carrier 1 and the developer carrier 5.
An electric field is formed through the intermediate transfer member 34, and the developer is electrostatically induced in accordance with the electric field, and flies and adheres onto the intermediate transfer member 34.

The developed image thus obtained is heat-transferred and fixed onto the transfer member 35 by a transfer roll 36 to become a fixed image 38 to obtain a permanent image. In addition, the code|symbol 37 is a presser roll.

As described above, the present invention maintains a conductive developer in a substantially single layer on an electrostatic latent image carrier or a developer carrier facing an electrode, and then applies this developer to an electrostatic latent image carrier. The electrostatic latent image or image is transferred to the developer in an electric field formed by the electrostatic latent image carrier or electrode and the developer carrier. A developing device that induces a charge having a polarity opposite to the voltage applied to an electrode to cause developer to fly only in an image area for development, and a developer is provided with a flying developer so as to control the flying of the developer in the development area. The present invention relates to a developing device characterized by being provided with a drag generating means for generating a drag due to non-electrostatic force in the opposite direction.

With such a developing device, (1) the toner particles themselves can be developed into a substantially monolayer; (2) the charge amount of each toner particle is faithful to the corresponding latent image;
There is no variation for a latent image with the same potential. ■ The amount of charge of each toner particle is not affected by changes over time or environmental changes. ■ The amount of transferred toner particles is always constant for a latent image with the same potential. 1. The toner does not fly or adhere to non-image areas; 2. The developed toner image does not move into or around the image, and does not peel off from the image area. .

Therefore, the developing device is capable of preventing image quality defects such as disturbances, roughness, trailing, uneven density, or fogging of developed images, and is also capable of obtaining high-quality developed images that do not change over time or in the environment. It is related to.

Finally, specific examples will be explained in detail to facilitate understanding of the present invention.

Carbon black and magnetite are added as conductive powder to epoxy resin, kneaded, and then pulverized with a jet mill. Carbon black is added and heat treated to adsorb onto the surface, which is then classified. A conductive toner was obtained. When the volume resistivity of the toner was measured under an electric field of 5×10 3 V/am, it showed a volume resistivity of 3×10 hΩ. On the other hand, 25μm on the aluminum pipe
After forming a thick photoreceptor layer made of selenium and uniformly charging the photoreceptor, a light image was applied to obtain an electrostatic latent image at an image potential of 1 kV. Furthermore, a single layer of toner is formed by rolling it in a toner holding container on the surface of the conductive porous material maintained at a distance of 0.3 from the latent image by a spacer roller, and the electrostatic charge is applied onto the layer. When the latent images were placed facing each other and developed, it was possible to obtain developed images that had a high image density of 1.3, had no density unevenness, had sharp images, and were further free from fog.

"Effects of the Invention" As explained above, by using the present invention, it is possible to obtain high-quality images that do not change over time or in the environment.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a developing device according to an embodiment of the present invention, FIG. 2.3.4.5 is an explanatory diagram showing a means for generating development drag, and FIGS. ) and (d) are explanatory diagrams of a developer carrier, and FIGS. 7 and 8 are explanatory diagrams showing modified examples of the present invention. ■...Latent image carrier, 2...Latent image, 3...Visible image, 4
...Developer layer, 5...Developer carrier, 6...Developer holding member, 7...Development bias, 8...Developer,
9... Adhesive layer, 10... Conductive substrate, 11... Mesh. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (d) Figure 7 Figure 8 Continuation of page 1 Akira Hirano Ryo - 227 Hongo, Ebina City
Takashi Saito - 227 Hongo, Ebina City
No. 4 Business Office No. 1 Yoshihiko Fujimura Hongo 2, Ebina City
274 office address Akira Okamoto removed 2274 Hongo office location, Ebina city

Claims (1)

[Claims] (1) A conductive developer is held in almost a single layer on a developer carrier facing an electrostatic latent image carrier or an electrode, and then this developer is kept in a non-contact state with the electrostatic latent image carrier or electrode. The developer is transported to a developing area in such a manner that the developer is charged with a charge of opposite polarity to the voltage applied to the electrostatic latent image or electrode in an electric field formed by the electrostatic latent image carrier or electrode and the developer carrier. A developing device that performs development by directing the developer to fly only in the image area, and in order to control the flying of the developer in the development area, a drag force due to a non-electrostatic force in a direction opposite to the direction of flight of the developer is applied. A developing device characterized by being provided with a drag generating means for generating.