JPS63309981A - Developing device - Google Patents

Abstract

PURPOSE:To facilitate the exchange of developer and to improve the carrying force of new developer by providing at least one of fixed magnets disposed on a magnetic roll so that the magnetic force of both poles appear on the peripheral surface of a developing sleeve. CONSTITUTION:A main magnet N1 and sub magnets S1 and S2 disposed on the magnetic roll 12A provide the axis of a permanent magnet in a radius direction, and make only either magnetic pole opposite to the developing sleeve 11. But the sub magnet N2 is made to turn both poles of N and S to a peripheral direction so that the magnetic force appears on the peripheral surface of the developing sleeve 11. The sub magnet N2 is arranged and fixed in order to make its same pole S adjacent to the sub magnet S2 which positions on the upper part of the rotation of the developing sleeve 11. Thus, the carrying faculty and the exchangeability of the developer is enhanced even in a developing device where the developing sleeve 11 having a short diameter is used.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a #electrostatic latent image formed on an image carrier, which is developed by the rotation of a developer carrier containing a magnetic roll on which an electrostatic latent image is fixed. The present invention relates to a developing device for a recording device.

[Background of the invention]

Conventionally, a three-component developer using a one-component developer containing a magnetic material or a two-component developer using a mixture of toner and a carrier that is a magnetic material has been used, for example, a magnetic brush developing device as shown in FIG. used. In the figure, 31 is an image carrier that rotates in the direction of the arrow, and is a photosensitive layer of, for example, ZnO, Se, etc., and 32 is a developing sleeve that is a developer carrier made of a non-magnetic cylinder that rotates in the direction of the arrow. Developer D
e to the development area E. Reference numeral 33 denotes a magnetic roll in which a plurality of magnets of different polarities are arranged radially in an alternating manner, and its magnetic force causes the developer De to adhere to the developing sleeve 32 and forms spikes.

Reference numeral 34 denotes a spike regulating section provided on the upstream side of the development area E, which regulates the thickness of the developer layer so that the maximum likelihood latent image is developed under the best condition. Reference numeral 35 denotes a bias power supply applied to the developing sleeve 32, which is a DC bias for preventing, for example, toner scattering and development capillary, and 35a denotes a protective resistor.

In this magnetic brush developing device, there are two types: one is to fix the magnetic roll 33 and rotate the developing sleeve 32 to perform development, and the other is to rotate the magnetic roll 33 as well to perform development.

However, the magnetic flux density and magnetic field distribution of the magnetic pole required for developer transport and the magnetic flux density and magnetic field distribution of the magnetic pole required for good development in the development area are generally different, and the magnetic roll rotating type is different from the fixed type. Drive compared to 8! Since there are disadvantages such as a complicated structure, a magnetic roll fixing system in which magnets with different magnetic forces are arranged is advantageous.

Regarding the direction of rotation of the developing sleeve 32, there are two methods in which development is performed while the rotating image carrier surface and the rotating developing sleeve surface rotate in the same direction (forward direction) in the developing area E, and a method in which development is performed while rotating in the opposite direction. There is a method to do this. However, developing by rotating in the opposite direction tends to cause a decrease in the density at the leading edge of the image (first of all, the leading edge of the solid area), and it is difficult to transport the developer stably in the development area E, resulting in the formation of a layer of developer. Since then, development is often performed by forward rotation.

In any of the above methods, the developer layer regulated by the spike control member 34 forms a developer flow, is conveyed on the developing sleeve, and is conveyed to the development area E, where development is performed. The developer flow that has completed the development is conveyed to the developer reservoir in a form that adheres to the developing sleeve 32, but the developer that has completed the development is piled up while remaining attached to the developing sleeve 32 and is transferred to the developing area E. In order to prevent the developer from being conveyed, a scraper 36 is provided which slides into contact with the developing sleeve 32 and acts to strip off the developer.

Generally speaking, the outer diameter of conventional developing sleeves is 40 to 50 m.
At about +sφ, the magnetic roll is also 6 to 10 on the surface of the developing sleeve.
A device with a fixed permanent magnet that has a magnetic force of about 1000 mm was used, but recently, due to the miniaturization and cost reduction of developing devices, a developing sleeve with a small outer diameter of about 20111111φ has been used. Became.

[Problem that the invention seeks to solve]

Naturally, a small-diameter magnetic roll is used for such a small-diameter developing sleeve, so due to the space required to arrange the magnet body, it is necessary to install the permanent magnet axis in the radial direction, so that only one magnetic pole is attached to the circumferential surface of the developing sleeve. If they are arranged like a hailstorm, it is not possible to have a large number of magnetic poles, and as a result, the ability to transport the developer around the circumference of the developing sleeve is insufficient, or when using a two-component developer, the developer still adheres to the developing sleeve after the development process. There was a problem in that it was difficult to replace the developer being used.

That is, as shown in FIG. 6(A), both main magnet N1 and S
When using a magnetic roll 33A consisting of two sub-magnets S1 and 82 arranged so that the magnetic force of the pole appears on the circumferential surface of the developing sleeve 32A, there are sub-magnets of the same polarity on the circumferential surface of the developing sleeve 32A. Since the repulsive magnetic field generated by S1 and 82 is shaped like 1&, the developer with a high carrier component ratio after the development process can be moved to the developing sleeve in this repulsive magnetic field even if a plate or the like is not brought into sliding contact with the developing sleeve 32A. Although it has the feature that it can be easily removed from the circumferential surface of the developing sleeve 32A and replaced with a new developer with an appropriate component ratio of toner and carrier, the developer conveyance ability on the circumferential surface of the developing sleeve 32A is limited because the number of magnetic poles is too small. This has the disadvantage that the density of the image to be developed is insufficient and the developer is scattered outside the developing device.

On the other hand, as shown in FIG. 6 (B), when using a magnetic roll 33B in which a sub-magnet N2 is arranged between two sub-magnets S1 and 82 to produce an N-pole magnetic force on the circumferential surface of the developing sleeve 32B, The ability of the developing sleeve 32B to hold and transport the developer is kept higher than that shown in FIG. 6(A), but on the other hand, it is difficult to replace the developer because no repulsive magnetic field is formed on the circumferential surface. This causes unevenness in image density, and it is therefore necessary to install a scraper or the like to remove the remaining carrier.

However, since this scraper is an elastic member that presses against the surface of the rotating developing sleeve, there is a risk of damaging the surroundings, and it also results in braking the rotation of the developing sleeve, so its installation is not desirable from a functional standpoint.

The present invention solves and improves this problem, and as a result, it is possible to easily replace the developer after the development process, while using a small-diameter developing sleeve, and to maintain sufficient conveying force without scattering the new developer. The object is to provide a developing device that can be transported to a developing area.

[Means for solving problems]

The above purpose is to provide a developing device that develops a latent image on an image carrier using a developer conveyed by a magnetic roll that is fixedly provided and a developer conveyed by a developing sleeve that rotates around the outer periphery of the magnetic roll. , at least one is achieved by a developing device characterized in that it is provided so that magnetic forces of both poles appear on the circumferential surface of the developing sleeve.

〔Example〕

Embodiments of the present invention are shown in FIGS. 1 to 4.

FIG. 1 shows the structure of a developing device according to the present invention. It is arranged on a substantially horizontal side surface of the photosensitive drum 20, which is an image carrier inside the recording apparatus.

The developing device main body 10A includes a developing sleeve 11 that rotates during development, a fixed magnetic roll 12 contained in the developing sleeve 11, a stand-up regulating member 13 provided with a slight gap from the circumferential surface of the developing sleeve 11, and a developing sleeve 11. The toner conveying member 15, 16, 17 is provided with a stirring member 14 for mixing and stirring the toner, and the toner conveying member 15, 16, 17 is provided with a stirring member 14 for mixing and stirring the toner.
When the toner is replenished via the stirring member 14, first the stirring member 14
mixes the toner with the carrier held by the developing device main body 10A to produce a two-component developer with uniform toner content density, and then the developing sleeve 11 attracts the developer to its circumferential surface by the magnetic force of the magnetic roll 12.・The developing sleeve 11 is conveyed and subjected to the cutting action by the spike regulating member 13.
The amount of adhesion and conveyance to the photosensitive drum 20 is regulated.
The structure is such that the development abrasion surface, so-called development area, is made to stand up.

That is, in this state, by applying a DC bias voltage to the developing device 111, the toner component of the developer on the circumferential surface of the developing sleeve 11 is transferred to the electrostatic latent image on the circumferential surface of the photosensitive drum 20, and the image is developed. It is now time to change the world.

The photosensitive drum 20 is an aluminum drum with an outer diameter of 100 mm as a support and a photoconductive layer of 5e-Te (selenium-tellurium) is provided thereon. It is rotated, is positively charged in advance, and is exposed to an original image in an exposure device. The developing sleeve 11 has an outer diameter of 25 m.
It is a small diameter sleeve of +φ or less, and in this example, the outer diameter is 2.
0 Theory - Made of φ stainless steel with a wall thickness of 0.7 to 0.
Sandblasting the outer periphery with a thin circular part of 8m11+ ($30
), which is rotated counterclockwise in FIG. 1 at a circumferential speed 2.5 times that of the photosensitive drum 20, and the distance between the surfaces of the photosensitive drum 20 (D , S, D) are set at positions that maintain 0.5 mm.
It has been done.

On the other hand, the magnetic roll 12 is made of a cylindrical aluminum material with four rod-shaped solid main magnets embedded in the inner peripheral surface of the developing sleeve 11 with a gap of about 0.5 mm maintained between them. In the developing device filO of the present invention, the fixed magnets are arranged on the magnetic roll 1 shown in the embodiment shown in FIG. 2(A).
Magnetic roll 1 shown in the embodiment of 2A or 14 (A)
The magnetic roll 12 of either type 2B is used.

The lengths of the fixed magnets embedded in the magnetic rolls IZA and 12B in the same direction are 81 for the main magnet N1 and 81 for the sub magnet S1. , N 2 and S 2 are all 41, and in the case of the magnetic roll 12A, the main magnet N1 and [1 magnet S
1 and S2, and in the case of the magnetic roll 12B, the main magnet N1 and the sub magnet N2 . S2 is provided with a sleeve of permanent magnets in the radial direction, and only one magnetic pole is attached to the developing sleeve 11.
However, in the magnetic roll 12A, the sub magnet N
On the other hand, in the magnetic roll 12B, the N and S poles of only the sub magnet S1 are oriented in the circumferential direction so that magnetic force is applied to the circumferential surface of the developing sleeve 11, and located on the upstream side of the rotation of the developing sleeve 11. Each IJI magnet S
2 or the same polarity as N2 are fixed in an arrangement such that they are adjacent to each other.

In this case, the magnetic force of the mutually adjacent magnetic poles of each side magnet has a peak magnetic force at the angle shown in the figure on the circumferential surface of the developing sleeve 11. In the case of the magnetic roll 12A, the main magnet N1 has a peak magnetic force of 950 Gauss, and the sub magnet S1 has a peak magnetic force of 950 Gauss, 82 is 55 each
Furthermore, sub-magnet N2 is added to make it 0 gauss and 450 gauss.
In the case of the magnetic roll 12B, the main magnet N1 is 950 Gauss, and the sub magnets N2 and 82 are 5507 Gauss and 450 Gauss, respectively. Furthermore, regarding the sub magnet S1, the N pole is 450 Gauss and the S pole is 40 Gauss.
It is configured to be 0 Gauss.

The embodiment shown in FIG. 3 is similar to the embodiment shown in 1R2tK, and has the magnet shape and magnetic force on the surface of the developing sleeve 11 shown in the following table. According to experiments, the sub magnet S
By arranging the 1-pole center at an angle of 120° to 130° from the main magnet N1-pole center, a good developing effect can be obtained.

Sub-magnet N2 in the magnetic roll 12A, sub-magnet S1 in the city record magnetic roll 12B, and magnetic roll 12
The sub magnet N in C is as shown in FIG. 2(B), i13(B) and FIG. 12B, 1
It is arranged at an angle substantially perpendicular to the straight line @XX connecting the center C of the 2C and the 9J magnet N2.81 or N in each of the above.

Note that the surfaces of the sub magnet N2 in the magnetic roll 12A, the sub magnet S1 in the magnetic roll 12B, and the sub magnet N in the magnetic roll 12C, which face the developing sleeve 11, are on the inner circumferential surface of the developing sleeve 111. Needless to say, there is no need to make the sub-magnet N2. Sl and N are fixed to magnetic rolls 12A, 12B and 12C, respectively.

Furthermore, as is clear from the above embodiment, the side ends of the sub-magnets in which both magnetic poles appear on the circumferential surface of the developing sleeve 11 are arranged at an angle of 120 degrees or more from the center of the main magnet N1. .

In this way, the present invention arranges both poles of one specified sub-magnet in the circumferential direction, thereby forming more magnetic poles than the number of magnets on the circumferential surface of the small-diameter developing sleeve 11, and using the magnetic force to spread the developer. This ensures reliable conveyance and also makes it possible to form a repulsive magnetic field on one side between adjacent sub-magnets, making it easy to replace carrier components and preventing the developer being conveyed to the development area from detaching during conveyance. This means that the toner can be fed to the developing area while maintaining a constant toner density without causing any damage.

〔Effect of the invention〕

According to the present invention, even in a developing device that uses a small-diameter developing sleeve, the developer conveying ability and replaceability are improved, and as a result, the developer is not scattered during conveyance.
In addition, a developing device capable of stably forming a latent image on an image carrier into a toner image without unevenness has been provided.

[Brief explanation of the drawing]

Figure @i is a sectional view of the developing device of the present invention. FIGS. 2, 3, and 4 are cross-sectional views of the magnetic roll used in the device and views of its main parts. FIG. 5 is a block diagram of a conventionally common developing device. The ptSc diagram is a cross-sectional view of a conventional general small-diameter magnetic roll. 10...Developing device 10A...Developing device main body 10B...Toner supply section 11...Developing sleeves 12, 12A, 12B...Magnetic roll 13...
・Standing control member 14 ... Stirring member 20 ... Photosensitive drum N1 ... Main magnet S 1 , N 2 , S 2 ... Sub-magnet applicant Konishiroku Photo Industry Co., Ltd. Figure 2 (A) Figure 2 (B) 12A salary p''' Figure 3 (△, Figure 3 (B) 2C Figure 4 (8ri 5a

Claims (3)

[Claims] (1) In a developing device that develops a latent image on an image carrier using a developer conveyed by a magnetic roll that is fixedly provided and a developer conveyed by a developing sleeve that rotates around the outer periphery of the magnetic roll, a fixed magnet that is provided on the magnetic roll is used. . A developing device characterized in that at least one of the two polar magnetic forces is provided on the circumferential surface of the developing sleeve. (2) The developing sleeve is a small diameter sleeve with an outer diameter of 25 mm or less, and the developing sleeve surface has a magnetic force distribution of 5 poles including a magnetic pole by a main magnet. Developing device. (3) The side end of the stationary magnet, at which the at least one pole appears on the circumferential surface of the developing sleeve, is arranged at an angle of deviation of at least 120° from the center of the main magnet. Developing device according to item 1 or item 2.