JPH03164770A - Developing device - Google Patents

Abstract

PURPOSE:To stably attach necessary quantity of fully charged toner to a latent image on a photosensitive body and to form a distinct toner image by allowing the fiber of a toner supply means to capture the toner with the aid of magnetic field generated by a magnetic field generation means and supplying the toner to a developing roller. CONSTITUTION:The magnetic field is generated in a developing device 10 by the magnetic field generation means 16 and the toner supplied to the developing device 10 is captured by the fiber 15 made of a magnetic material of the toner supply means 12 with the magnetic field and gravity. By rotating the toner supply means 12, the sufficient toner is supplied to the developing roller 11 because the fiber 15 which fully captures and holds the toner comes in contact with the developing roller 11, and the fiber 15 comes in contact with the developing roller 11 while it moves with the magnetic field, so that the toner is uniformized and supplied to the developing roller 11. Thus, the necessary quantity of toner is stably supplied to the latent image on the photosensitive body from the developing roller 11 and the distinct toner image is always formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing device, and particularly to a developing device used in an image forming apparatus such as a copying machine.

[Prior Art] An image forming apparatus such as a copying machine has a method of supplying toner to form a visualized toner image on a latent image formed on a photoreceptor by exposure corresponding to an image on a document. A developing device is provided.

JP-A-105573/1983 discloses this type of developing device. This developing device.

A developing roll is disposed within the housing facing the cylindrical sleeve and the opening of the housing, a photoreceptor is disposed closely facing the developing roll, and a magnet is housed within one cylindrical sleeve.

As a developer, a magnetic carrier and two
A two-component developer consisting of negatively charged toner mixed with 7% by weight is used, and this developer is supplied to the cylindrical sleeve.

DC power is applied between the developing roller and the cylindrical sleeve,
The negatively charged toner in the developer is electrostatically attracted to the developing roller, the developing roller is rotated at the same speed as the circumferential speed of the photoreceptor, and the cylindrical sleeve is rotated at two to three times the speed of the developing roller. The toner is rotated, and the toner is brought into sliding contact with the latent image on the photoreceptor to perform development.

In the developing device according to this disclosure, since a two-component developer is used, a magnet for holding the carrier in the cylindrical sleeve must be provided, which limits the degree of freedom in device design. In addition, the carrier tends to scatter, and the carrier adheres to the developing roller, damaging the toner thickness forming means provided on the developing roller, and in some cases, the carrier adhering to the roller may be developed and cause background stains. .

In order to solve these problems, developing devices using a one-component developer made only of toner have come into use.

Further, in a developing device using a one-component developer disclosed in Japanese Patent Application Laid-Open No. 62-95558, a toner supply roller to which toner is supplied from a toner hopper is formed of a conductive elastic material such as polyurethane. Different voltages are applied depending on the IE polarity of the toner used in the developing roller and the toner replenishing roller, each of which has a rubber magnetic layer formed around the core material.

In this developing device, the toner supplied to the toner supply roller is charged by friction with the surface of the developing roller, is electrostatically attracted to the developing roller, and is transported to a developing area where development is performed.

In a developing device using a one-component developer disclosed in Japanese Patent Publication No. 63-50706, toner is directly supplied from a hopper to a developing roller, and a cylindrical magnet that rotates independently is arranged inside the developing roller. has been done. A magnetic fiber made of, for example, stainless steel is attached to the circumferential surface of the developing roller.

In the developing device according to this disclosure, the magnetic fiber that conveys the toner is moved by the rotation of the cylindrical magnet, and the toner that adheres to the latent image forms a -like toner image.

[Problems to be Solved by the Invention] As mentioned above, carrier scattering in a developing device using a two-component developer, damage to the toner thickness forming means by the carrier, background stains due to carrier development, or problems due to device design. The problem of limited degrees of freedom is solved by using -component developers.

However, in a developing device using -component developer.

In the method disclosed in Japanese Patent Application Laid-Open No. 62-95558, actual measurements by the inventors showed that the supply of toner from the toner replenishment roller to the developing roller was higher than the set applied voltage between the replenishing roller and the developing roller. It has been confirmed that the stability of toner supply is lacking because it often depends on the mechanical characteristics between the two.

Furthermore, in the developing device disclosed in Japanese Patent Publication No. 63-50706, the toner is directly supplied from the hopper to the developing roller, so the toner is not sufficiently charged and the toner is not sufficiently supplied to the latent image. If this is not done, a clear toner image may not be obtained.

An object of the present invention is to provide a developing device that can stably supply toner at each stage, stably supply the necessary amount of toner to the latent image on the photoreceptor, and always form a clear toner image. It is about providing.

[Means for Solving the Problems] The above object is to provide a toner supply means which is disposed in contact with a developing roller and has a magnetic fiber on its surface, and which supplies toner to the developing roller; This is achieved by providing a magnetic field generating means for applying a magnetic field.

[A magnetic field is formed within the developing device by the working magnetic field generating means,
The toner supplied to the developing device is captured by the magnetic fibers of the toner supply means by gravity and the magnetic field within the developing device.

Then, as the toner supply means rotates, the fibers that have sufficiently captured and held toner come into contact with the developing roller, so that a sufficient amount of toner is supplied to the developing roller. Further, depending on the magnetic field formed in the developing device, the fibers are moved by the magnetic field and come into contact with the developing roller, so that the toner is uniformly supplied to the developing roller.

Therefore, the necessary amount of toner is stably supplied from the developing roller to the latent image on the photoreceptor, and a clear toner image is always formed.

[Example 1 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the overall configuration of each embodiment of the present invention, FIG. 2 is an explanatory diagram showing the configuration of main parts of the first to fourth embodiments, and FIG. FIG. 4 is an explanatory diagram showing the configuration of the main part of the sixth embodiment. FIGS. 5 and 6 are explanatory diagrams showing the configuration of the fiber in each embodiment. It is.

In these figures, 1 is a photoreceptor, 2 is a charger, 3 is a transfer device, 4 is a cleaner, 5 is a cleaning blade, 6 is a static eliminator, 7 is a case, 10 is a developing device, 11 is a developing roller, 12 is a Toner supply roller, 13, agitator, 14
15 is a thin layer blade, 15 is a magnetic fiber, 15a is a sleeve, and 16A to 16D are magnets.

As shown in FIG. 1, a developing roller 11, a toner replenishing roller 12 serving as toner supplying means, an agitator 13, and a thin layer blade 14 are provided in a case 7 in which an open lower a is formed.
The developing device 10 is configured by housing the developing device 10 .

That is, a developing roller 11 is disposed so as to be freely rotatable around a shaft with its end protruding from the opening lower a, and a toner replenishing roller 12 is disposed in contact with this developing roller 11 so as to be freely rotatable around the shaft. ing. Further, a thin layer blade 14 is disposed close to and opposite to the developing roller 11, and an agitator 13 is rotatably disposed at one end of the bottom of the case 7.

A photoreceptor 1 is disposed close to and opposite the developing roller 11 of the developing device 10 and is rotatable about a shaft.

This photoreceptor 1 is grounded. A charger 2 is arranged above the photoreceptor 1 in close opposition to it, and a transfer device 3 is arranged below it in close opposition to it.

In the rotation direction θ of the photoreceptor 1, a cleaner 4 is adjacent to the transfer device 3 and faces the photoreceptor 1 in close proximity.
is equipped with a brush 4a and a cleaning blade 5. A static eliminator 6 is disposed between the cleaner 4 and the charger 2 so as to closely face the photoreceptor 1 .

Further, the developing roller 11 has a structure in which an insulating layer is formed on the surface of a conductive member, and a bias power source E4 is connected to this conductive member. The toner replenishment roller 12 includes a sleeve 15a made of a conductive non-magnetic material (for example, aluminum), to which one end of a fiber 15 of magnetic material is fixed, and the other end of the fiber 15 has a radius. It extends protrudingly in the direction.

This fiber 15 is made by mixing ferrite or magnetite into a resin such as nylon or Teflon, and forming each fiber to have a diameter of 0.00511I11 to 0.1al111, an electrical resistance of 10s to 107Ω, a Cl11 elastic modulus of 0.2 to
21N/m'' linear fiber, and one end of this linear fiber is attached to a sleeve 15 with adhesive 8 as shown in FIG.
a, they are fixed so as to protrude parallel to each other in the radial direction.

Furthermore, as shown in FIG. 6, the above-mentioned linear fibers can be woven into a woven fabric and the free end side can be finished into a loop shape. In this case, 300 to 20 linear fibers are used.
It is preferable to collect about 00 lines and arrange them at equal intervals.

Furthermore, the fiber 15 can be constructed by fixing one end of a magnetic wire made of stainless steel, for example, to the sleeve 15a with a conductive adhesive, and having the other end protrude parallel to each other in the radial direction. In this case, the entire fiber 15 attached to the sleeve 15a becomes electrically conductive.

Further, the bias power source E2 is applied to the sleeve 15a of the toner replenishing roller 12, and although FIG. 1 shows a case where the bias power sources E, E2 are DC power sources, these power sources are AC power sources. Alternatively, it may be a power source in which direct current is superimposed on alternating current.

In the first embodiment, as shown in FIG. 2, a magnet 16D, which is a magnetic field generating means, is disposed on the outside of the case 7 of the developing device 10, facing the toner replenishing roller 12.

Next, the operation of the first embodiment having such a configuration will be explained.

The photoreceptor 1, which has been completely transferred to the transfer paper, is indicated by the arrow θ in FIG.
, reach the cleaner 4 position while rotating in the direction, and move the brush 4.
Due to the contact rotation of a and the sliding action of the cleaning blade 5, residual toner on the photoreceptor 1 is removed. Next, the photoreceptor 1 is discharged from residual static charge by the static eliminator 6, and then uniformly charged by the charger 2.

In this way, for the photoreceptor 1 charged in a negative manner,
At the exposure position T shown in FIG. 1, light modulated by the image of the original is irradiated, and a latent image corresponding to the image of the original is formed on the photoreceptor 1.

On the other hand, the toner supplied to the developing device 10 in FIG. 16D
and is captured by the fiber 15.

The toner captured by the fiber 15 is indicated by the arrow θ.

The toner replenishing roller 12 rotating in the direction transports the toner to a position facing the developing roller 11.
The toner replenishing roller 12 and the developing roller 11, which rotate in the same direction at a circumferential speed two to three times as much as the toner replenishing roller 12 and the developing roller 11, are rotated in opposition to each other. Due to this rotation, the toner is charged by friction with the surface of the developing roller 11, and the bias power source E1. E2 causes the toner to be electrostatically attracted to the developing roller 11 by an electric field formed between the toner supply roller 12 and the developing roller 11.

The toner adsorbed to the developing roller 11 in this way is
The thickness is regulated by the thin layer blade 14, and the toner is frictionally charged between the developing roller 11 and the thin layer blade 14, and is deposited on the latent image at the development position facing the photoreceptor 1, so that a toner image is formed on the photoreceptor 1. It is formed.

In the first embodiment, a sufficient amount of toner is captured by the fiber 15, and the captured toner is charged by friction with the surface of the developer roller 11, and further frictionally charged between the developer roller 11 and the thin layer blade 14. Since development is performed in a sufficiently charged state, the required amount of toner is always stably supplied and a clear toner image is formed.

In addition, the bias power supply E1. By adjusting E2, the toner captured by the fiber 15 is transferred to the developing roller 11 and the photoreceptor 1.
It is possible to set the optimum development conditions by controlling the supply amount. Further, cleaning can also be performed by peeling off the toner on the developing roller 11 and supplying new toner to the developing roller 11.

Magnetic fiber 15. By making the sleeve 15a and the adhesive 8 conductive, the bias power source E2 can be easily applied to the sleeve 15a, and the set voltage by the bias power source E2 can be applied directly to the toner without charging the fiber 15 itself. can be made to act.

Since the sleeve 15a is made of a non-magnetic material, the magnetic field created by the magnet 16D does not short-circuit in the sleeve 15a portion, and the magnetic field can effectively act on the fiber 15.

In the second embodiment, as shown in FIG. 2, a magnet 16C for forming a magnetic field is disposed within the toner replenishing roller 12, and the sleeve 15a is rotatable about the shaft.

In this second embodiment, the magnet 16C is attached to the toner replenishing roller 1.
By arranging the magnet 16C in the developing device 110, there is no need to provide a separate space for the magnet 16C, and the developing device 10 is made smaller.

The configuration and effects of other parts of the second embodiment are the same as those of the first embodiment already described.

In the third embodiment, as shown in FIG.
is provided, and the sleeve 15a is rotatable around the shaft.

In this third embodiment, a magnetic dipole is formed in the fiber 15 of the sleeve 15a passing through the magnet 16B position, and the free end of the fiber 15 is moved by the magnetic field of the magnet 16B, and the toner captured in the fiber 15 is removed. By raising the fiber 15 in the protruding direction, the developing roller 1
1 and the toner, and stable toner supply to the developing roller 11 can be achieved.

The configuration and effects of other parts of the third embodiment are the same as those of the first embodiment already described.

In the fourth embodiment, as shown in FIG. 2, a magnet 16A is disposed within the developing roller 11, and the developing roller 11 is formed into a cylindrical shape and is configured to be freely rotatable about an axis.

In this fourth embodiment as well, a magnetic dipole is formed in the fiber 15 passing through the magnet 16A position, and the free end of the fiber 15 is moved by the magnetic field of the magnet 16A, and the toner captured by the fiber 15 is transferred to the fiber 15. By raising the toner in the protruding direction, the contact between the developing roller 11 and the toner can be improved, and toner can be stably supplied to the developing roller 11. Furthermore, in the fourth embodiment, the magnet 1
By integrating 6A with the developing roller 11, the apparatus can be made more compact.

The configuration and effects of other parts of the fourth embodiment are the same as those of the first embodiment already described.

In the fifth embodiment, as shown in FIG.
A cylindrical magnet 18 is provided in the magnet 18 so as to be independently rotatable, and different magnetic poles are sequentially formed adjacent to each other in the axial direction of the magnet 18.

In the fifth embodiment, in the same direction as the developing roller 11, two to
The magnet 18 rotates within the sleeve 15a of the toner replenishing roller 12, which rotates at three times the circumferential speed, at a rotation speed greater than the rotation speed of the sleeve 15a.

When the magnet 18 rotates, the toner captured by the fiber 15 is transported around the fiber 15 and
A magnetic dipole is formed in the fiber 15 by the rotation of
The free end of fiber 15 moves. In this case, the movement of the fiber 15 at any point depends on the gradient end of the magnetic field created by the magnet 18.

For example, by making the magnetic properties of each fiber 15 different, each fiber 15 can be caused to move differently in the circumferential direction and in the lateral direction.

By this movement of the fiber 15, the toner captured by the fiber 15 is transferred to the sleeve 15 of the toner supply roller 12.
It is possible to stably supply the fiber 15 with good contact to the developing roller 11 in a state in which the movement of the fiber 15 caused not only by the rotation of the magnet 18 but also by the rotation of the magnet 18 is superimposed.

The configuration and effects of other parts of the fifth embodiment are the same as those of the first embodiment already described.

In the sixth embodiment, as shown in FIG. 4, the magnet 18A has a configuration in which the magnet 18A has a spiral magnetic pole in the axial direction, unlike the fifth embodiment. This magnet 18A is created with a desired magnetic field pitch by finely magnetizing the magnet in a spiral shape, or by cutting a ferrite formed in advance from a rubber or plastic sheet after magnetization, and attaching it in a spiral shape. Created by As such a ferrite material, for example, EPDM rubber mixed with 85 parts by weight of barium ferrite is used.

In this sixth embodiment, a magnetic dipole is formed in the fiber 15 by the rotation of the magnet 18A, and the free end of the fiber 15 is moved in a direction parallel to the axial direction and in a circumferential direction by the magnetic field of the magnet 18. , the toner captured by the fibers 15 is uniformly supplied to the developing roller 11 in the circumferential and axial directions.

Further, since the toner remaining in the sleeve 15a of the toner supply roller 12 is moved in one direction of the shaft, it is convenient to collect it in a hopper and reuse it.

The configuration and effects of other parts of the sixth embodiment are as follows.

This is the same as the first embodiment already described.

[Effects of the Invention] As described above in detail, according to the present invention, the fibers of the toner supply means sufficiently capture toner by the magnetic field generated by the magnetic field generation means, and the toner is stably supplied to the developing roller. This allows a necessary amount of sufficiently charged toner to stably adhere to the latent image formed on the photoreceptor, thereby forming a clear toner image.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the overall configuration of each embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of main parts of the first to fourth embodiments of the present invention, and FIG. 3 is an explanatory diagram of the configuration of main parts of the first to fourth embodiments of the present invention. FIG. 4 is an explanatory diagram of the configuration of the main part of the fifth embodiment of the present invention, FIG. 4 is an explanatory diagram of the configuration of the main part of the sixth embodiment of the present invention, and FIGS. FIG. 2 is an explanatory diagram of a fiber configuration in FIG. 1...Photoreceptor, 2...Charger, 3...
...Transfer device, 4...Cleaner, 4a...
...Brush, 5...Cleaning blade,
6... Static eliminator, 7... Case, 8...
...adhesive, 10...developing device, 11...
Developing roller, 12... Toner supply roller, 13... Agitator, 14... Thin layer blade, 15... Fiber, 15a...・
... Sleeve, 16A-16D ... Magnet, E
1 to E,...Bias power supply, T...Exposure position, D...Development position. No.! figure

Claims (1)

[Claims] A developing device that develops a latent image formed on a photoreceptor by toner includes a developing roller that develops the latent image by bringing the toner into sliding contact with the latent image, and a developing roller that is placed in contact with this developing roller and is applied to the surface. A developing device comprising: a toner supply means that includes a fiber made of a magnetic material and supplies toner to a developing roller; and a magnetic field generation means that applies a magnetic field to the toner supply means.