JPH0131611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention develops latent images such as electrostatic images formed in electrophotography, electrostatic recording, electrostatic printing, etc., or magnetic images formed in magnetic printing, etc. The invention relates to a developing device for

In general, there are two known methods for developing an electrostatic charge image to form a visible image: a wet developing method using a liquid developer, and a dry developing method using a powder developer. The latter method, which is superior in that it does not require a solvent, is further divided into a method using a two-component developer consisting of a carrier and toner, and a method using a single-component developer consisting only of toner.

Therefore, in the development method using a one-component developer, there is essentially no change in toner concentration, which simplifies the configuration of the developer, and the characteristics of the developer do not deteriorate over a long period of time. Although it is superior to systems using two-component developers in that it is possible to stably obtain images without using any This is because it is difficult to charge the developer to the required state and to cause the developer to act on the electrostatic image support in the required state during development.

In other words, in order to obtain a good visible image using the dry development method, it is necessary to charge the toner so that it has a polarity opposite to that of the electrostatic charge image to be developed and a charge amount of an appropriate amount. In the system using a two-component developer, the toner is triboelectrified by mechanically stirring the toner and carrier, so by selecting the characteristics of the carrier, stirring conditions, etc. It is possible to control charge polarity and charge amount to a considerable extent. However, in a single-component developer consisting only of toner, such a carrier does not exist, so
It is very difficult to control the toner charge polarity and charge amount.

On the other hand, in conventional developing devices, in order to charge the developer, it is necessary to provide a developer charging mechanism independent of the developer transport body, and this developer charging mechanism makes the developing device considerably large. Furthermore, although high positional accuracy is required, it is difficult to fully satisfy this requirement.

The present invention eliminates the above drawbacks, makes it possible to charge a one-component developer to a desired charging state, achieves good development, and occupies a small space, simplifying the overall configuration. The purpose is to provide a developing device.

This purpose consists of a developer transport body for transporting a one-component developer, and the developer transport body has, in its surface portion, a first electrode and a first electrode disposed therebetween via a charging space. The developing device has a large number of electrode pairs each including two electrodes, and an alternating electric field is formed in the charging space by the first electrode and the second electrode. achieved.

The present invention will be specifically explained below with reference to the drawings.

First, the principle of charging the one-component developer (hereinafter referred to as "toner") used in the present invention will be explained.

In Figure 1, 1A and 1B are electrode plates provided facing each other, and the electrode plate 1A is connected to a DC power source EA.
is connected to the electrode plate 1B, and an AC power source V and a DC power source EB are connected to the electrode plate 1B so as to be superimposed thereon.
On the opposing surfaces of the electrode plates 1A and 1B, charging members 2A,
2B are provided respectively, and these charging members 2A,
The space between 2B constitutes a charging space 3. When the toner T is introduced into the charging space 3 and an alternating electric field is formed via the electrode plates 1A and 1B by the AC power supply V, the toner T flies in the charging space 3 due to the action of this alternating electric field. As a result, the particles of toner T become charged, and the mechanism is as follows.

That is, since the toner T is in the form of powder particles, it is slightly electrically charged even in its natural state, and even if it is not electrically charged at all, the particles remain until it is introduced into the charging space 3. They become electrically charged due to friction between them or friction with conveying members, instruments, vessel walls, etc.

However, when an electric field acts, a Coulomb force is applied to the toner particles due to the fact that the toner particles are electrically charged, even if only slightly, or due to the charge being injected into the particles if they are conductive. When the alternating electric field is applied as described above, the toner particles begin to vibrate according to the alternating oscillation of the electric field. That is, when an AC power source V is used, in a half cycle of the voltage, toner particles fly in the charging space 3 in the direction toward the charging member 2A or 2B and collide with them, and in the next half cycle, the toner particles fly in the direction toward the charging member 2A or 2B and collide with them. The charging member 2B or 2 flies in the direction
A, this is repeated, and as a result, the toner particles are charged by friction when they collide with the charging member 2A or 2B.

The charge polarity of the toner T due to this friction is
It is determined by the relative relationship in the triboelectric charging order between the materials of the charging members 2A and 2B and the toner T,
Therefore, by selecting these materials so that the toner T is charged to a desired polarity, the toner T can be charged to any positive or negative polarity.

The charging state of the charged toner particles obtained by such means depends on the voltage and frequency of the AC power source V, the combination of polarities and voltages of the DC power sources EA and EB, or if the toner T is a magnetic toner and the magnetic force When the toner T is applied, it is controlled by the magnitude of the magnetic force and other factors, so by selecting these conditions and the conditions in the configuration of the charging space 3, the toner T can be charged to a desired charging state. The toner particles charged to a certain amount or more adhere to the charging member 2A or 2B, although this is influenced by the effects of the DC power sources EA and EB.

In the above, it is practically necessary that at least a part of the surface of the charging members 2A and 2B is electrically conductive, so that the charge generated on the charging member 2A or 2B due to collision with toner particles is required. It is possible to maintain an electrical balance with the battery and prevent charge from accumulating. Moreover, the electrode plates 1A, 1B
If the charging members 2A and 2B are made to also function as charging members, independent charging members 2A and 2B are unnecessary.

The present invention utilizes a charging means based on the principle as described above.
To explain the configuration of the figure as an example, a developing drum 12 is provided in the developing area of a latent image supporting drum 11 made of a photoconductive photoreceptor, and is opposed to the latent image supporting drum 11, and the toner T filled in a toner tank 13 is In the developing device configured to convey the toner to the developing area, the developing drum 12, which is a toner conveying body, is provided with a first electrode and a second electrode located across the charging space from the first electrode on its surface portion. A large number of pairs of electrodes are formed, and an alternating current power source is connected to form an alternating electric field between the first electrode and the second electrode. To explain an example of the structure of the electrode pair, for example, as shown in FIG. Electrode 21A
A large number of electrode pairs are formed thereon, with second electrodes 21B formed thereon via an insulating material 22.

According to this configuration, the toner particles supplied to the surface portion of the developing drum 12 are used for charging along the side surface of the insulating material 22 between the first electrode 21A and the second electrode 21B constituting the electrode pair. In the space, due to the action of an alternating electric field there, it vibrates as shown by the arrow, or vibrates between the first electrode 21A and the second electrode 21B of an adjacent pair through the space. It becomes electrically charged.

Various modifications can be made to the specific configuration of the electrode pair consisting of the first electrode 21A and the second electrode 21B. For example, in the example shown in FIG. 4, the first electrode 21A is provided so as to cover the surface of the insulating support layer 20,
The example of FIG. 5 has a configuration in which an insulating material 22 is provided on the electrode 21A and a second electrode 21B is formed thereon.
In the example shown in FIG. 6, which has a plurality of second electrodes 21B formed thereon, the first electrode 21A is embedded in the insulating support layer 20 along the surface thereof, and In the configuration in which the second electrode 21B is buried in the insulating material 22 provided to protrude above, the example shown in FIG. 22
The example shown in FIG. 8 has a configuration in which a first electrode 21A is provided on the surface of the insulating support layer 20 between them, and a second electrode 21B is provided on the insulating material 22. An insulating material 22 is provided protrudingly on the surface of the insulating support layer 20 .
burying the first electrode 21A along the exposed surface of the
The structure in which the second electrode 21B is provided on the insulating material 22, the example of FIG. In the example shown in FIG. 10, insulating materials 22 are provided on the insulating support layer 20 so as to face each other with a space between them. The structure in which the first electrode 21A and the second electrode 21B are provided in a protruding manner and are embedded in alternately adjacent insulating materials 22, 22, the example shown in FIG. Insulating materials 22, 22 are provided on the insulating materials 22, 22 protruding from each other so as to face each other with a space therebetween, and first electrodes 21 are provided on alternately adjacent insulating materials 22, 22.
In the example shown in FIG. 12, an insulating support is provided. A control electrode 23 is embedded along the surface of the layer 20, and the insulating support layer 2
In the example of FIG. 13, the first electrode 21A and the second electrode 21B are provided on the surface of the substrate 0 in the same manner as in FIG. 9. In addition to providing the second electrode 21B, a second electrode 21B is further provided on each of the first electrodes 21A via an insulating material 22, and a second electrode 21B is provided on each of the first electrodes 21A via an insulating material 22.
A first electrode 21A is placed on 1B via an insulating material 22.
In the example of FIG. 14, the first layer is provided on the insulating support layer 20.
This first electrode 21A is provided protrudingly.
An insulating material 22 is provided on the insulating support layer 20 so that the electrode 1A is embedded therein, and a second electrode 21B is provided on the surface of the insulating material 22 in an area adjacent to a region corresponding to the first electrode 21A. , 21B are provided in a protruding manner, and the example shown in FIG. 21A and the second electrode 21B are buried so as to be alternately spaced apart from each other,
The first electrode 21A and the second electrode 21B are made of an insulating material 2
The toner particles vibrate and become electrically charged as shown by arrows. The control electrode 23 controls the state of vibration of the toner particles by applying a suitable DC voltage thereto, and as a result controls the state of charge of the toner.

As in each of the above configuration examples, it is only necessary that a space is formed that allows the vibration of toner particles.
This space becomes a charging space, and the direction of vibration itself is not limited. Moreover, various configurations other than the above configuration examples are possible. Of course, in order to charge the toner to the required state, it is important to select the material of the portion with which toner particles collide with each other by taking into account the triboelectric charging order. In each of the illustrated configuration examples, the electrode 21A or 21B is shown as a rectangle for convenience.
A rectangular shape is not necessarily preferable due to the requirement of suppressing discharge at the edge portion, the requirement of allowing electric lines of force to effectively act on the toner, and manufacturing requirements. Further, as the material of the insulating support layer 20 and the insulating materials 22 and 24, resin or rubber is usually used.
As the material for the first electrode 21A, the second electrode 21B, and the control electrode 23, resin or metal in which conductive powder is dispersed is preferably used.

Although some specific configuration examples of electrode pairs effective in the present invention have been conceptually or schematically shown above, they can actually be manufactured, for example, as follows.

Manufacturing Example 1 An aluminum drum with a diameter of 50 mm is used as a base, and as shown in FIG. A copper metal layer 32 having a thickness of about 20 microns is formed by sputtering, and then a photoresist and etching technique is used to form a regular array on the metal layer 32 as shown in FIG. 16B. 16 holes 33 each having a diameter of 70 microns are formed using a solvent.
As shown in Figure C, the portion of the insulating material layer 31 exposed by the hole 33 was dissolved and removed to form a hole 34 and the surface of the substrate was exposed, thereby producing a developing drum. The drum thus obtained has the base body 30 as the first
If the remaining portion of the metal layer 32 is used as the second electrode, the electrode pair structure will be similar to that shown in FIG.

Production Example 2 Copper was further deposited on the surface of the product obtained in Production Example 1 to a thickness of about 30 microns by sputtering, and the thickness of the metal layer 32 on the insulating material layer 31 was changed as shown in FIG. At the same time, the exposed surface of the base 30 due to the hole 34 was covered with a metal layer 35. The drum thus obtained has an electrode structure similar to that shown in FIG. 7, with the metal layer 35 serving as the first electrode and the metal layer 32 serving as the second electrode.

Manufacturing Example 3 Using an aluminum drum with a diameter of 30 mm as a base, as shown in FIG. 18A, an insulating photoresist film 41 with a thickness of about 50 microns was formed on the outer peripheral surface of the base 40 by a dipping method. , and conductive carbon is further dispersed thereon by a dipping method to a thickness of approximately 2.
By forming a micron conductive photoresist film 42, then irradiating it with light using a mask, and then dissolving and removing the uncured portion, as shown in FIG. 18B.
As shown in FIG.
Then, regularly arranged holes 43 each having a diameter of 100 microns were formed in the insulating photoresist film 41.
The drum thus obtained has an electrode pair structure similar to that shown in FIG. 4, with the base 40 serving as the first electrode and the remaining portion of the conductive photoresist film 42 serving as the second electrode. It is.

Manufacturing Example 4 Using an aluminum drum with a diameter of 50 mm as a base, an insulating material layer 51 with a thickness of about 50 microns was formed on the outer peripheral surface of the base 50 as shown in FIG. 19A, and then as shown in FIG. 19B. This insulating material layer 51
5 holes, each 70 microns in diameter, arranged regularly in
2 is formed, copper is deposited on the entire surface so that the hole 52 is filled, and then the copper on the insulating material layer 51 is removed by polishing to fill the hole 52 with metal as shown in FIG. 19C. A layer 53 is formed, and copper is deposited on this surface using a sputtering method using a mask to a thickness of about 100 microns.
As shown in FIG. 19D, a metal layer 53' is formed on the metal layer 53, and the entire metal layer 53' is a continuous metal layer having portions extending along the circumference with each of the metal layers 53' as the center. A layer 54 was formed on the insulating material layer 51. The drum obtained here has the integral metal layers 53, 53' as the first electrode, and the metal layer 54 as the second electrode.
The electrodes have a similar electrode pair structure to the example shown in FIG.

The toner is charged while being conveyed by the developing drum 12 configured as described above, and this charged toner is conveyed by the developing drum 12 to the developing area facing the latent image support drum 11 with the electric force due to the charging applied. and is subjected to development by a known developing means, thereby forming the latent image support drum 1.
The electrostatic charge image on 1 is visualized.

As can be understood from the above manufacturing examples, when using a developing drum, it is preferable that the base drum is made of metal and used as a conductive path for the first electrode. When an insulating drum is used as an insulating drum, its outer peripheral surface may be coated with a metal layer. The same applies when a belt is used instead of the developing drum. Furthermore, by forming the second electrode into a continuous net-like structure, it is possible to easily conduct electricity therethrough.

The developing device shown in FIG. 2 has the drum manufactured according to Manufacturing Example 1 described above as the developing drum 12, and the metal layer 32 is connected to an AC power source V and a DC power source E.
1 are superimposed and connected, and a DC power source E2 is connected to the base body 30. Toner particles are supplied as a layer with a thickness of at most 100 microns.
While being conveyed by the developing drum 12 due to the action of these power sources, the inner circumferential surface of the hole 34 is vibrated and charged in the height direction, and in the developing area, it adheres to the electrostatic latent image on the latent image support drum 11 and is developed. will be carried out. Here, as the AC power source V, one having a frequency of 50 Hz to 50 KHz and a voltage of 10 V to 2 KV is used, and as the DC power source E1 or E2, a positive or negative voltage of 0 to 500 V is used. Further, the distance between the latent image supporting drum 11 and the developing drum 12 is 0 to
It is desirable that the thickness be maintained at approximately 500 microns, which is greater than the thickness of the toner layer on the developing drum 12. 14 is a toner amount regulating member that regulates the amount of toner conveyed to the developing area to an appropriate amount; 15 is a cleaning member that collects toner not used for development in the developing area into the toner tank 13. It is something.

The developing device shown in FIG. 20 has the following features except that an AC power source V and a DC power source E1 superimposed thereon are connected to the base 30, and a DC power source E2 is connected to the metal layer 32.
It has the same configuration as FIG. 2. In this case as well, as the AC power source V, a frequency of 50 Hz to 50 KHz and a voltage of 10 V to 2 KV is used, and as the DC power source E1 or E2, a positive or negative voltage of 0 to 500 V is used. Further, the distance between the latent image supporting drum 11 and the developing drum 12 is preferably maintained at about 0 to 500 microns, and is preferably larger than the thickness of the toner layer on the developing drum 12.

The example shown in FIG. 21 is a developing device suitable for using magnetic toner as the toner, and has a structure in which a magnet 60 is provided in the developing drum 12 in the structure shown in FIG. It is transported using the magnetic force of Furthermore, the cleaning section also has a rotating sleeve 61 and a magnet body 62 inside thereof, which collects toner that has not been used for development. The developing conditions are the same as when using the apparatus shown in FIG.

In development tests conducted using each of the developing devices having the configurations shown in FIGS. 2, 20, and 21, good development was achieved in all of them.

Accordingly, in the present invention, a large number of electrode pairs constituted by a first electrode and a second electrode are provided on a toner conveying body such as a developing drum or a developing belt that conveys toner to a developing area. Since the toner is charged by an alternating electric field, the toner can be charged to a desired charging state and good development can be achieved, and the toner conveying body itself has a toner charging function. Therefore, there is no need to provide an independent toner charging mechanism, and the space occupied can be reduced, the overall configuration can be greatly simplified, and furthermore, toner transport and development using applied voltage can be Control can also be easily performed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the developer charging method used in the present invention, FIG. 2 is an explanatory diagram showing the configuration of an embodiment of the present invention, and FIGS. 3 to 15 are respectively diagrams for the present invention. An explanatory diagram showing a specific configuration example of an electrode pair that can be effectively used. FIGS. 16A to 16C are explanatory cross-sectional views showing a method for manufacturing a developing drum that can be used in the present invention in order of steps. FIG. 17 is an illustration of another developing drum. 18A and B, and FIGS. 19A to 19D are explanatory sectional views showing the manufacturing method of other developing drums in the order of steps, respectively.
FIGS. 20 and 21 are explanatory diagrams showing the configuration of other embodiments of the present invention, respectively. 1A, 1B...electrode plate, 2A, 2B...charging member, 3...charging space, T...toner, V...
AC power supply, EA, EB, E1, E2...DC power supply,
11...Latent image support drum, 12...Developing drum,
13... Toner tank, 14... Toner amount regulating member, 15... Cleaning member, 20... Insulating support layer, 21A... First electrode, 21B... Second electrode, 22, 24... Insulating material, 23... Control electrode, 30, 40, 50... Substrate, 31, 51...
...Insulating material layer, 41...Insulating photoresist film,
42... Conductive photoresist film, 32, 35,
53, 53', 54...metal layer, 33, 34, 4
3,52...hole.

Claims (1)

[Scope of Claims] 1. A developer transporting body that transports a one-component developer, and the developer transporting body has a first electrode and a charging space connected thereto in its surface portion, respectively. A developing device comprising a large number of electrode pairs constituted by positioned second electrodes, and an alternating electric field is formed in the charging space by the first electrode and the second electrode. . 2. The developing device according to claim 1, wherein the developer is a one-component magnetic developer. 3. The developing device according to claim 1 or 2, wherein an alternating voltage on which a direct current voltage is superimposed is applied between the first electrode and the second electrode.