JP2563014Y2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a toner carrier that carries and transports toner on its surface while being rotated, and a layer of toner that is carried and transported by the toner carrier. The present invention relates to a developing device that includes a layer thickness regulating unit that regulates the thickness, and visualizes an electrostatic latent image formed on a latent image carrier with toner whose layer thickness is regulated by the layer thickness regulating unit.

[Conventional technology]

In an image forming apparatus such as an electronic copying machine, a laser printer, or a facsimile, which obtains a recorded image by visualizing an electrostatic latent image formed on a latent image carrier, a toner to which an auxiliary agent is added as necessary, It is conventionally well known to employ a developing device of the above type using a component-based developer.

This type of developing device has the advantage that the maintenance of the device can be simplified and the structure of the device can be reduced, as compared with a developing device using a two-component developer containing a carrier.

By the way, in a developing device using a one-component developer, in order to form a high-quality visible image of a predetermined density, a large amount of sufficiently charged toner is conveyed to a developing area, and a latent image is formed by the toner. It needs to be visualized.

When a magnetic toner is used, a large amount of toner can be carried on the toner carrier by utilizing the magnetic force of a magnet provided in the toner carrier, so that the above-described requirement can be satisfied relatively easily. is there. However, when a non-magnetic toner is used, it cannot be easily carried on the toner carrier by a magnetic force, so that it is not easy to satisfy the above requirements.

Therefore, the present applicant uses a toner carrier having a conductive surface on the surface of the substrate and a dielectric material fixed to the substrate regularly or irregularly exposed on the surface of the conductive substrate. By charging the body to a predetermined polarity, a minute closed electric field is formed in the vicinity of the toner carrier surface, and the toner used for visualizing the electrostatic latent image is adhered to the toner carrier surface by the closed electric field. Has proposed a developing device for visualizing a latent image with the toner (Japanese Patent Application No. 2-15110).

With this developing device, a large amount of sufficiently charged toner can be carried on the toner carrier by the action of the closed electric field, and a high quality visible image can be obtained. However, such a toner carrier has a problem in that the cost is relatively high.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device which can exhibit the function of the above-described developing device as it is, and can be configured at low cost and easily.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a developing device of the type described at the outset, wherein the toner carrier forms a conductive substrate and a dielectric substance on the surface of the substrate in a regular or irregular pattern. And a dielectric material formed by transferring the toner image on the toner carrier. It is located downstream of the development area where visualization is performed, and contacts the surface of the toner carrier to charge the dielectric to a predetermined polarity, thereby forming a minute closed electric field near the toner carrier surface. Carrier charging means,
A toner charging unit for charging the toner supplied to the toner carrier to a predetermined polarity; and a statically upstream side of a toner layer thickness regulating unit by the layer thickness regulating unit with respect to a rotation direction of the toner carrier. The toner charged on the surface of the toner carrier, which is located on the downstream side of the development area where the visualization of the electrostatic latent image is performed and is charged by the carrier charging means to form a minute closed electric field, is continuously charged. And a toner supply unit for supplying the toner to the developing device.

In order to achieve the same object, the present invention provides a developing device of the type described at the beginning, wherein the toner carrier is
A conductive substrate, and a dielectric formed by transferring a dielectric substance on the surface of the substrate in a regular or irregular pattern. It is located on the upstream side of the toner layer thickness regulating unit by the thickness regulating unit, on the downstream side of the developing area where the electrostatic latent image is visualized, and on the surface of the toner carrier while being rotationally driven. The toner is charged to a predetermined polarity in contact with the surface of the toner carrier to form a minute closed electric field in the vicinity of the surface of the toner carrier, and the toner supplied to the toner carrier is charged to a predetermined polarity. And a toner supply roller for continuously supplying charged toner to the surface of the toner carrier on which the toner is formed.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing an example of the developing device according to the present invention, and first, its overall configuration and operation will be clarified.

In FIG. 1, a belt-shaped photoconductor 1, which is an example of a latent image carrier, is driven in the direction of arrow A, and a developing device 2 is provided opposite to the photoconductor. In the toner container 3 of the developing device 2, a non-magnetic toner 4 to which an auxiliary agent is externally added as necessary, that is, a non-magnetic one-component developer is stored. The specific volume resistivity of the toner is about 10 ⁷ to 10 ¹² Ωcm. On the front and rear side plates of the toner container 3, a developing roller 5 is supported in a state where a part thereof is exposed from an opening of the container. The developing roller 5 faces the photoreceptor 1 and is, for example, 400 rpm in a counterclockwise direction in FIG. It is driven to rotate at the rotation speed. The developing roller 5 is an example of a toner carrier, but a belt-shaped toner carrier may be used instead of the roller 5. A toner supply roller 6 which is an example of a toner supply member is supported on front and rear side plates of the toner container 3. The roller 6 contacts the developing roller 5 at a rotation speed of, for example, 300 rpm in a counterclockwise direction (or in a clockwise direction). Good).

The toner 4 in the toner container 3 is conveyed to the toner supply roller 6 while being stirred by the agitator 7 rotating clockwise, and then supplied to the developing roller 5 by the roller 6. At the time of this supply, the toner is frictionally charged to a predetermined polarity, in this example, a positive polarity opposite to the electrostatic latent image of the photoconductor 1,
The toner adheres electrostatically to the peripheral surface of the developing roller 5 and is carried by the developing roller 5. The configuration and operation related to this will be described later in detail.

As described above, the toner supplied and carried on the peripheral surface of the developing roller 5 is conveyed by the rotation of the roller 5, is leveled by the doctor blade 8 which is an example of a layer thickness restricting means, and is regulated to a uniform thickness. . Next, the toner is conveyed to a developing area 9 where the photoconductor 1 and the developing roller 5 are opposed to each other,
Here, the latent image is electrostatically transferred to the electrostatic latent image formed on the photoconductor 1, and the latent image is visualized.

The toner that has not passed through the development area 9 without being used for development is returned to the toner supply roller 6 while being carried on the development roller 5. Further, the visible image formed on the photoreceptor 1 is transferred to a transfer sheet (not shown) and fixed on the transfer sheet by a fixing device.

As described above, the developing device 2 according to the present embodiment includes the toner carrier including the developing roller 5 that carries the toner on the surface thereof while being driven to rotate, and the layer of the toner carried and carried by the toner carrier. And a layer thickness regulating unit configured as a doctor blade 8 for regulating the thickness. The electrostatic force formed on the latent image carrier made of the photoreceptor 1 by the toner whose layer thickness is regulated by the layer thickness regulating unit. Visualize the latent image.

The above-described configuration itself is no different from a conventionally known developing device. In such a conventional developing device, it is difficult to transport a large amount of sufficiently charged toner to a developing area, and the density of a visible image may be reduced. was there.

In the illustrated developing device, FIGS.
As schematically shown in the figure, the developing roller 5 is made of a conductive base made of a conductive roller 10 such as aluminum, for example. ) 11 is provided. Thus, on the surface of the developing roller 5, the conductive surface 12 of the conductive roller surface and the dielectric 11 fixed to the roller 10 are exposed in a regular or irregular state. The shape and size of each dielectric 11 can be appropriately set, but if the shape is a short shape as shown in FIG. 3, the length D1 of one side is, for example, about 10 to 500 μm, and a circle. If the diameter is, for example, 10
The distance D2 between the dielectrics 11 is set to, for example, about 10 to 500 μm. In addition, each dielectric may be formed in a triangle or another shape, and the respective shapes may be different. Further, a dielectric material having a minute width is extended along the surface of the conductive roller 10, and the width and the interval thereof are, for example, 10 to 500.
It can be set to an appropriate value of about μm. The ratio of the surface area of the dielectric 11 to the total surface area of the developing roller 5 is, for example,
It is about 30 to 70%.

The values exemplified above and the shape of the dielectric 11 are appropriately selected so that the electric field strength of a closed electric field described later is increased and an optimal amount of toner can be attached to the developing roller 5.

When the toner carrier comprises a belt, a minute or minute width dielectric is fixed to the surface of the conductive substrate of the belt.

As the dielectric 11, a polarity opposite to the charging polarity of the toner,
In this example, a material that is frictionally charged to a negative polarity is selected.

On the other hand, the toner supply roller 6 in contact with the developing roller 5
Regarding the rotation direction of the developing roller 5, the doctor blade 8
Is located upstream of the toner layer thickness regulating portion and downstream of the developing area 9, contacts the surface of the developing roller 5, and causes the dielectric 11 to have a polarity opposite to the charged polarity of the toner. A negative electric field is formed in the vicinity of the surface of the developing roller 5 as described later. Thus, the toner supply roller 6 serves as a carrier charging unit for charging the developing roller 5. FIG. 1 and FIG.
In the example shown in the figure, the toner supply roller 6 is made up of a conductor core member 14 and a cylindrical foam 15 laminated therearound, and this foam 15 is pressed against the developing roller 5 while being elastically deformed. I have. When such a toner supply roller 6 is used, the foam 15 may be made of a material that frictionally charges the dielectric 11 to a negative polarity as described above. Instead of the foam 15, a well-known material such as a fur brush may be used.

The more detailed operation of the above configuration will be described below.

As described above with reference to FIG. 1, the developing roller portion that has passed the developing area 9 moves to the toner supply roller 6 and contacts the roller 6. Here, the developing roller 5
The toner not supplied to the development carried on the top is scraped off by the scavenging force received from the toner supply roller 6. At the same time, the dielectric 11 of the developing roller 5
Comes into contact with the toner supply roller 6 and is charged to a negative polarity opposite to the charging polarity of the toner by the friction. that time,
Even if an electrostatic residual image due to the influence of the electrostatic latent image on the photoconductor 1 remains on the dielectric 11 on the peripheral surface of the developing roller that has passed through the developing area 9, the friction with the toner supply roller 6 causes the dielectric 11. Is charged to a substantially saturated state, and the charge amount becomes uniform, so that the residual image is eliminated and the developing roller 5 is initialized.

On the other hand, the toner carried to the developing roller 5 while being in contact with the peripheral surface of the toner supply roller 6 is frictionally charged to a positive polarity by friction with the toner supply roller 6 as schematically shown in FIG. At this time, the toner is further frictionally charged to a more positive polarity due to the friction with the developing roller 5, particularly the dielectric 11, and is electrostatically attached to the peripheral surface of the developing roller 5. As described above, the toner supply roller 6 serves as a toner charging unit for charging the toner supplied to the developing roller 5 to a predetermined polarity, and continuously supplies the charged toner to the surface of the developing roller 5. It serves as a toner supply unit.

At this time, each of the dielectrics 11 of the developing roller 5 is negatively triboelectrically charged, and the conductive surface 12 of the conductive roller 10 exposed on the surface is present around each of the dielectrics 11. The surface is in a state where a negative charge is applied to many dielectrics 11. As a result, as shown in FIG.
12, a small closed electric field (microfield) is formed near the surface of the developing roller 5. That is, when considering lines of electric force representing the state of the electric field, lines of electric force E are formed in the space near the surface of the developing roller 5 as represented by a large number of arc-shaped lines in FIG.
The lines of electric force exit from the developing roller 5 and return to the same developing roller 5, so that a closed electric field is formed between each dielectric 11 and the conductive portion 12. Thus, an electric field having a large electric field gradient is formed near the surface of the developing roller.

Since the surface area of each dielectric 11 is very small as described above, the intensity of each closed electric field is greatly increased by the so-called edge effect or fringing effect (peripheral electric field effect).
Due to such a closed electric field, the positively charged toner becomes a dielectric material.
The roller 11 is strongly pulled and held on the roller 5 in such a state that it is hard to separate. At this time, the toner is strongly frictionally charged due to the friction between the toner supply roller 6 and the developing roller 5 and is held on the surface of the developing roller 5 by the action of a strong closed electric field. A large amount of charged toner is carried. In addition, the toner carried on the developing roller 5 is a doctor blade 8 made of, for example, urethane.
When the layer thickness is regulated, the toner having a sufficient charge is strongly held on the surface of the developing roller 5 by the minute closed electric field, but the toner having a small charge amount is removed by the contact pressure with the doctor blade 8, and eventually. Only the toner having a large charge amount is conveyed to the developing area 9 in a larger amount than in the related art, and the electrostatic latent image is visualized as described above. The electric field between the developing roller 5 and the photoconductor 1 in the developing area 9 has a large electrode effect, and the toner on the developing roller 5 is likely to adhere to the photoconductor 1. In this way, the image density of the visible image is increased,
In addition, soil on the ground can be prevented.

In the vicinity of the surface of the developing roller 5, only a small closed electric field is formed over the entire surface, as schematically shown in FIG. 4, and a case where an electric field other than the closed electric field is mixed in the closed electric field. However, in any case, since a closed electric field is present, the intensity is increased and a large amount of toner can be carried.

In a conventionally known developing device, about 0.1 to 0.3 mg / cm ² of toner can be attached to the surface of the developing roller after passing through a doctor blade, but 0.4 to
Since it was necessary to attach about 0.5 mg / cm ² of toner, the amount of toner attached on the developing roller was insufficient. Therefore, conventionally, the rotation speed of the developing roller is increased, and the linear speed is set to about three to four times the linear speed of the photoreceptor, thereby increasing the amount of toner conveyed to the developing area and increasing the density of the visible image. Methods to prevent the drop are also employed. However, when the linear velocities of both are set in this manner, the density of the solid image formed on the photoconductor becomes abnormally high only at the rear end side in the photoconductor movement direction as compared with other portions. And the image quality is degraded. In order to eliminate this problem, it is necessary to make the linear velocity of the developing roller equal to or close to the linear velocity of the photoconductor, but in this case, for example, 0.8 to 1.2 mg / cm ² on the developing roller. And the conventional developing device cannot cope with this. However, in the developing device shown in FIG. 1, 5 to 20 (preferably 10 to 20)
15) A large amount of toner charged to about μc / g (for example, 0.8 to 1.2 m
g / cm ² ) can be conveyed to the developing area, and the linear velocity of the developing roller 5 can be made equal to or close to the linear velocity of the photoconductor 1.

As described above, in the developing device according to the present invention, in the rotation direction of the toner carrier, the electrostatic latent image is visualized on the upstream side of the toner layer thickness regulating unit by the layer thickness regulating unit. Is located downstream of the developing area to be developed, and contacts the surface of the toner carrier to charge the dielectric to a predetermined polarity,
Carrier charging means for forming a minute closed electric field near the toner carrier surface, toner charging means for charging toner supplied to the toner carrier to a predetermined polarity, and layer thickness regulation with respect to the rotation direction of the toner carrier Is located on the upstream side of the toner layer thickness regulating portion by the means, and on the downstream side of the developing region where the electrostatic latent image is visualized, and is charged by the carrier charging means so that a minute closed electric field is generated. A toner supply unit for continuously supplying charged toner to the surface of the formed toner carrier. With this configuration, a sufficiently charged toner can be conveyed to a development area in a required amount, and a high-quality image can be formed.

At this time, in the developing device of this embodiment, the above-described carrier charging means, toner charging means, and toner supply means are constituted by the toner supply roller 6. That is, in the developing device of the present example, the developing area, in which the electrostatic latent image is visualized, is located on the upstream side of the toner layer thickness regulating unit by the layer thickness regulating unit in the rotation direction of the toner carrier. Is located further downstream, and contacts the surface of the toner carrier while being rotationally driven, charges the dielectric to a predetermined polarity, forms a minute closed electric field near the toner carrier surface, and A toner supply roller is provided for charging the toner supplied to the carrier to a predetermined polarity and continuously supplying the charged toner to the surface of the toner carrier on which the minute closed electric field is formed. With this configuration, the structure of the developing device is simplified,
And the cost can be reduced.

Although the non-contact development is performed in the development area 9 in the example of FIG. 1, the latent image may be visualized by a contact development method. If necessary, a bias voltage such as direct current, alternating current, superimposed direct current alternating current, or pulse may be applied to the conductive roller 10 of the developing roller 5 or the toner supply roller 6 to further enhance the quality of a visible image. it can. It is also possible to configure the conductive roller 10 to be simply grounded. Furthermore, in the above-described example, the dielectric 11 is charged to the opposite polarity to the toner, but the dielectric 11 is charged to the same polarity as the toner charging polarity, and a large amount of toner adheres particularly to the conductive surface 12 of the developing roller. It can also be done.

Next, the materials of the non-magnetic toner and the main members of the developing device will be exemplified for reference.

The toner is generally made of a resin such as polyester, BMA, polystyrene, epoxy, or phenol, and its charge polarity and charge amount can be controlled by a polarity control agent internally or externally added to the toner. The external addition is to mix an auxiliary agent such as a polarity control agent with the toner, and the internal addition is to knead the toner particles and integrate them.

Also, for the respective members of the developing device, for example, the following members are appropriately used in consideration of the charging polarity of the toner, the releasability from the toner, the durability, and the like.

Next, the details of the above-described developing roller 5 will be clarified by describing a manufacturing method thereof.

First, as shown in FIGS. 5 and 6, a conductive base, that is, a conductive roller 10 serving as a material of a developing roller is prepared. As the roller 10, a metal roller made of Al, Cu, Fe or the like is used.

On the other hand, a transfer drum 100 for transferring a dielectric substance is rotatably supported on a frame (not shown) of the manufacturing apparatus, and the above-described conductive roller 10 is rotatably supported on the frame in opposition to the transfer drum 100. .

As shown in the enlarged view of FIGS. 7 and 8, a large number of minute projections 101 having a shape and a surface area corresponding to the large number of dielectrics 11 shown in FIG. 3 are formed on the surface of the transfer drum 100. ing. Such a transfer drum 100 and the conductive roller 10
Are arranged to face each other with an extremely small gap δ as shown in FIG.

The transfer drum 100 and the conductive roller 10 are driven to rotate at the same peripheral speed in the direction indicated by the arrow in FIG. At this time, the flowable dielectric material 11a (FIG. 7) is applied to the surface of the minute protrusion 101 of the transfer drum 100 by the supply roller 102 rotating in the counterclockwise direction. Then, the dielectric material 11a is transferred to the surface of the conductive roller 10 in the transfer area 103 where the transfer drum 100 and the conductive roller 10 face each other. After the dielectric substance 11a is transferred to the entire peripheral surface of the conductive roller 10 in the form of a thin film and then dried and cured, the dielectric substance 11a comprising the dielectric substance 11a is provided, as shown in FIGS. 2 and 3. Is completed. Transfer drum 100 to conductive roller 10
In order to enhance the transfer effect of the dielectric substance 11a to the surface, the surface of the conductive roller 10 is cleaned in advance with a chemical, and very minute irregularities are formed on the surface of the roller 10 by a chemical or mechanical treatment. It is desirable that a dielectric substance be easily attached to the substrate.

The above-described manufacturing method is a method of printing the dielectric material 11a on the surface of the conductive roller 10 in accordance with the pattern of the projection 101 on the surface of the transfer drum. The rollers 5 can be mass-produced.

In the examples of FIGS. 5 to 8, a pattern of rectangular minute protrusions 101 is provided on the surface of the transfer drum, and the dielectric substance 11a is transferred to the surface of the conductive roller 10 in a pattern corresponding thereto. As described above, such a pattern may be regular or irregular. The shape of each protrusion 101 may be an appropriate shape such as a circle or a triangle, and the dielectric material 11a having a regular or irregular pattern corresponding to the shape may be transferred to the surface of the conductive roller 10. Ninth
The figure shows an example in which the surface projections 101 of the transfer drum 100 are formed in a lattice shape, and a dielectric 11 formed by the drum 100 is shown.
(See FIG. 3) corresponds to this shape, and a minute width dielectric material extending in a grid along the surface of the conductive roller 10.
11 is formed. Thus, by selecting the shape of the protrusion 101 formed on the surface of the transfer drum 100, the dielectric 11 having a desired form can be accurately formed.

When manufacturing a belt-shaped toner carrier, instead of the conductive roller 10, a substrate made of a conductive sheet 10a as shown in FIG. Then, after cleaning the surface thereof, the dielectric material applied to the protrusion 101 (FIG. 7) of the transfer drum 100 is transferred to the conductive sheet 10a while being fed in the direction of the arrow opposite to the transfer drum 100. This may be cured.

As described above, in the developing device according to the present invention, the toner carrier is formed of a conductive base and a dielectric formed by transferring a dielectric substance to the surface of the base in a regular or irregular pattern. Is provided.

In the embodiment shown in FIGS. 1 and 2, a minute electric field is formed in the vicinity of the surface of the toner carrier by charging the dielectric 11 to a predetermined polarity. Although the toner supply roller 6 is used as the carrier charging means for attaching the toner to be used to the toner carrier by the closed electric field, it is obvious that other independent carrier charging means may be used as appropriate.

[Effect of the invention]

As described above, according to the developing device of the present invention, a required amount of sufficiently charged toner can be conveyed to the developing area to form a high-quality image. Moreover, a toner carrier having a dielectric and a conductive portion exposed on the surface can be easily obtained at low cost, and the cost of the developing device can be reduced. Further, the accuracy of the surface shape of each dielectric can be easily increased.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a developing device, FIG. 2 is an explanatory diagram schematically showing a dielectric material of a developing roller and toner adhering to the roller with respect to other elements, and FIG. FIG. 4 is a plan view of the surface of the developing roller in which the dielectric is schematically enlarged, FIG. 4 is an explanatory view showing electric lines of force of a minute electric field formed between the dielectric and the conductive surface, and FIG. FIG. 6 is a front view of the conductive roller and the transfer drum, FIG. 6 is a side view thereof, FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG. 6, FIG. FIG. 10 is an enlarged plan view showing another example of a projection provided on the surface of the transfer drum, and FIG. 10 is an explanatory view showing a method for manufacturing a sheet-like toner carrier. 2 developing device 4 toner 6 toner supply roller 9 developing region 11 dielectric material 11a dielectric material

Continued on the front page (72) Inventor Naoki Iwata 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yuichi Ueno 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Ricoh (56) References JP-A-58-214176 (JP, A) JP-A-60-54150 (JP, U)

Claims (2)

(57) [Scope of request for utility model registration] A toner carrier that carries and transports toner on its surface while being rotationally driven; and a layer thickness regulating unit that regulates a layer thickness of the toner carried and transported by the toner carrier. In a developing device for visualizing an electrostatic latent image formed on a latent image carrier by a toner whose layer thickness is regulated by the layer thickness regulating means, the toner carrier has a conductive base, And a dielectric formed by transferring a dielectric substance on the surface of the base in a regular or irregular pattern. The toner layer thickness is determined by the layer thickness regulating means with respect to the rotation direction of the toner carrier. It is located on the upstream side of the regulating portion, is located on the downstream side of the developing region where the visualization of the electrostatic latent image is performed, and contacts the surface of the toner carrier to bring the dielectric into a predetermined polarity. Charged, minute in the vicinity of the toner carrier surface Carrier charging means for forming an electric field; toner charging means for charging toner supplied to the toner carrier to a predetermined polarity; and toner layer thickness regulation by the layer thickness regulation means with respect to the rotation direction of the toner carrier. Is located upstream of the developing unit and downstream of the developing area where the electrostatic latent image is visualized, and is charged by the carrier charging means to form a minute closed electric field. And a toner supply means for continuously supplying charged toner to the surface of the body. A toner carrier that carries and transports the toner on the surface thereof while being driven to rotate, and a layer thickness regulating unit that regulates a layer thickness of the toner carried and transported by the toner carrier. In a developing device for visualizing an electrostatic latent image formed on a latent image carrier by a toner whose layer thickness is regulated by the layer thickness regulating means, the toner carrier has a conductive base, And a dielectric formed by transferring a dielectric substance on the surface of the base in a regular or irregular pattern. The toner layer thickness is determined by the layer thickness regulating means with respect to the rotation direction of the toner carrier. On the upstream side of the regulating portion, located downstream of the developing region where the electrostatic latent image is visualized, and in contact with the surface of the toner carrier while being driven to rotate, the dielectric is removed. Charged to a predetermined polarity and loaded with toner A minute closed electric field is formed near the surface, the toner supplied to the toner carrier is charged to a predetermined polarity, and the toner charged on the surface of the toner carrier having the minute closed electric field is continuously charged. A developing device provided with a toner supply roller for supplying.