JPS63298375A - Developing device - Google Patents

Abstract

PURPOSE:To improve carriability of a developer to a developing area by setting the control position of a crest control member so that it is not interposed between repulsing magnetic fields above and below in the rotation direction of a developer carrier. CONSTITUTION:A magnetic roll 13B is used where a rubber magnet N3 whose N pole is directed to a developing sleeve 11 is attached to the end face, which faces a main magnet N1, of an auxiliary magnet S1 as one body, and repulsing magnetic fields generated between the main magnet N1 and the auxiliary magnet S1 are extinguished to prevent a crest control member 13 from being interposed between repulsing magnetic fields. Thus, the developer carrying capability of the small-sized developing sleeve 11 is stabilized to freely set the height of crests of the developer, and the quantity of carried developer and the crest state suitable for a development condition are obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrostatic latent image formed on an image carrier, which is developed by rotating 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, as a developing device 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, a magnetic brush developing device as shown in FIG. 5 has been used, for example. In Fig. 0, 31 is an image carrier that rotates in the direction of the arrow, for example, a photosensitive layer of ZnO, Se, etc., and 32 is a developing sleeve that is a developer carrier made of a non-magnetic cylindrical body that rotates in the direction of the arrow. Rotate and remove 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. 34 is the development area E
The spike regulating member is provided on the upstream side of the developer and regulates the thickness of the developer layer so that the electrostatic latent image is developed under the best condition. Reference numeral 35 represents a bias power supply applied to the developing sleeve 32, which is a DC bias for preventing, for example, toner scattering and development fog, and 35a represents 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. Compared to the conventional method, there are disadvantages such as a complicated drive mechanism, etc. Therefore, from this point of view, a magnetic roll fixing method in which magnets with different magnetic forces are arranged is advantageous.

Regarding the rotation direction 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 region E, and a method in which development is performed in the opposite direction. There is a method in which development is performed while rotating. However, developing by rotating in the opposite direction tends to cause a decrease in density at the leading edge of the image (especially the leading edge of the solid area), and it is difficult to transport the developer stably in the development area E (developer layering is likely to occur). , development is often performed by forward rotation. No matter which method is used above,
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;
In order to prevent the toner from being conveyed to the developing area E in an overlapping manner while adhering to the toner, 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 40~50mmφ.
In the past, the magnetic roll used was one in which a permanent magnet with a magnetic force of about 6 to 10 poles was fixed on the surface of the developing sleeve, but recently, due to the miniaturization and cost reduction of developing devices, the outer diameter of the developing sleeve has been reduced. A small-diameter developing sleeve with a diameter of about 20III and 11φ and containing a magnetic roll of 4 to 5 poles has come to be used.

[Problem that the invention seeks to solve]

When such a small-diameter developing sleeve is used, the length of the outer circumference of the developing sleeve is short, and three or more permanent magnets having a magnetic force of 400 Gauss or more are fixed at appropriate angle distribution on the surface of the developing sleeve as a magnetic roll. teeth,
For example, a main magnet N and an adjacent sub-magnet S on the rotational upstream side.
By arranging the spike control member between the developer sleeve and the developer sleeve, the regulated developer layer is adsorbed and held on the surface of the developing sleeve.
As the developing sleeve rotates, it becomes possible to be transported to the developing area and to be developed.

In this case, it is important not to provide a sub-magnet that causes spikes to stand between the main magnet N and the spike-setting regulating member on the upstream side of the rotation, in order to prevent the developer, especially the carrier, from scattering and to maintain good development. found that it is extremely effective.

The present inventors have developed a developing device with a built-in small-diameter developing sleeve by providing a spike regulating member between the main magnet N and the adjacent sub-magnet S on the rotational upstream side, thereby preventing the developer from scattering. , good developing performance could be obtained.

However, when the present inventors conducted various experiments on developing devices equipped with built-in developing sleeves that met the above conditions, it was found that although most of the conditions were satisfied, there were some differences, and there was a group that would be more desirable if improved. I found out what to do. Therefore, we conducted a detailed analysis to determine the outer circumference of the developing sleeve.
When we created a magnetic distribution table for 0°, we found that there was a common tendency for the above groups.

The present invention was made based on the second-class data, and is a developing device incorporating a small-diameter developing sleeve with an outer diameter of 25n+mφ or less, which has excellent developer conveyance to the developing area, and therefore can perform good development. It is an object of the present invention to provide a developing device in which the developer is not scattered and the developer is not scattered.

[Means for solving problems]

The above purpose is to provide a developer carrier having a magnetic roll inside which is arranged a magnet for development and a plurality of transport magnets for transporting the developer, and a spike regulating member to regulate the amount of spikes of the developer. This is achieved by a developing device equipped with the above-mentioned developing device, characterized in that the regulating position of the bristling regulating member is set so as not to be caught by a repulsive magnetic field on the upstream side and the downstream side with respect to the rotating direction of the developer carrier. .

〔Example〕

Examples of the present invention are shown in FIGS. 1, 2(B), and 3.

FIG. 3 shows the main structure of the developing device 10 to which the present invention is applied, before taking the measures according to the present invention.

The developing device 10 includes a developing device main body 10A and a developing device main body 10A.
The developing sleeve 11, which is a developer carrier built into the developing device main body 10A and is composed of a toner replenishing portion 10B integrally connected to the toner replenishing portion 10B, is a small-diameter sleeve with an outer diameter of 25 mm or less, and its circumferential surface is at least capable of developing. In this case, the photosensitive drum 20, which is an image carrier, is mounted at a position facing the circumferential surface of the photosensitive drum 20 at a predetermined distance and forming a developing area.

The photosensitive drum 20 is a photosensitive member having an aluminum drum having an outer diameter of 100 Iφ as a support and having a photoconductive layer of 5e-Te (selenium-tellurium) on the circumferential surface, and is rotated clockwise at a circumferential speed of 140 mm per second in FIG. It is positively charged by a charging electrode provided on the upstream side.

The developing sleeve 11 is a thin cylinder with an outer diameter of 20 mm and made of stainless steel with a wall thickness of 0.7 to 0.8 mm, the outer surface of which is roughened by sandblasting (30). It is rotated at a circumferential speed 2.5 times that of the photosensitive drum 20, that is, 330 revolutions per minute, and the distance in the developing area between its outer circumferential surface and the outer circumferential surface of the photosensitive drum 20 (D・S−D> is 0). .5
It is set to a position where it is maintained at mm.

Here, we will explain the developing roller and the spike control member according to the present invention. First, we will explain the state before the measures taken by the present invention, and then we will provide a comparative explanation of the measures and the embodiments of the present invention after the measures. conduct.

The magnetic roll 12 included in the developing sleeve 11 is equipped with a main magnet N1 as a permanent magnet related to development and sub magnets SL, N2, and S2 as transport magnets for transporting the developer on the outer peripheral surface of an aluminum bar. The main magnet N1
The photosensitive drum 20 is fixed at an angle such that it is tilted 5° to the upstream side and faces the central axis of the photosensitive drum 20.

The width dimension in the circumferential direction of each magnet is 8-ring for the main magnet N1, and 4 m+s for each of the sub-magnets Sl, N2, and S2, and the strength of the magnetic force on the circumferential surface of the developing sleeve 11 is 9-ring for the main magnet
50 gauss, sub-magnets S1 and 82 are 550 gauss, 450 gauss, respectively, and the N pole of sub-magnet N2 fixed transversely to the sleeve radial direction is 450 gauss, Si is 40 gauss.
0 gauss and arranged so that each peak magnet has the angular relationship shown in FIG.
1 at a position 100' in the rotational upstream direction of the developing sleeve 11. FIG. 2(A) shows the magnetic distribution on the circumferential surface of the developing sleeve 11 in this case, and shows that a weak S-pole repulsive magnetic field is generated between the main magnet N1 and the sub magnet S1. It shows.

The present inventors believe that the reason why the developer conveyance performance is slightly decreased is that even if the magnetic force is weak, it is trapped by the repulsive magnetic field of the S poles of the same polarity on the upstream and downstream sides of the spike regulating member 13. I inferred that this was due to its shape. and the first
As shown in the figure, a magnetic roll 13 is integrally equipped with a rubber magnet N3 having a width of 2 mm in the circumferential direction and having an N pole facing the developing sleeve 11 side on the end face of the main magnet Nl side of the sub magnet S1.
B was used under exactly the same conditions as in the case of magnetic roll IIA described above. In this case, the magnetic distribution on the peripheral surface of the developing sleeve 11 is as shown in FIG. 2(B), with the main magnet N1 and the sub magnet S1
The repulsive magnetic field that had been generated during this period disappeared, the spike-stiffing regulating member was no longer caught in the repulsive magnetic field, and it was found that the developer conveyance performance was also significantly improved.

Regarding the developer conveyance characteristics of the developing roller, if the gap H between the spike-up regulating plate 13 and the developing sleeve 11 is made small, there will be a noticeable difference in the conveyance characteristics between the good and bad conveyance characteristics. When using the improved magnetic roll 13B, experiments were conducted with various gap amounts H, and the comparisons shown in the following table were made.
The above improvement measures were proven to be effective.

〔Effect of the invention〕

The present invention has been made based on the discovery that the development characteristics can be improved by configuring the spike control member in the rotational direction of a small-diameter developing sleeve so that it is not caught in the repulsive magnetic field even if one side is induced. Therefore, the present invention stabilizes the developer conveyance capacity of a small-diameter developing sleeve, making it possible to freely set the cutting height of the developer and adjusting the developer conveyance amount suitable for the developing conditions. Thus, a developing device is provided which is capable of developing a toner image with a high quality and a bristling state, and in which scattering of the developer is extremely small.

[Brief explanation of drawings]

Fig. 1 shows the cross-sectional structure of the magnetic roll improved by the present invention, Fig. 2 (A) shows the magnetic distribution on the circumferential surface of the developing sleeve using a general magnetic roll, and Fig. 2 (B) shows the same as Fig. 1. Magnetic distribution diagram on the circumferential surface of the developing sleeve due to the magnetic roll shown, 3rd
The figure is a cross-sectional view of a developing device before the measures taken according to the present invention are applied, and FIG. 4 is a cross-sectional configuration diagram of a general magnetic roll.
FIG. 5 is a configuration diagram of a conventional developing device. 10A-m-Developer body 10B-m=Toner supply section 1
1--Developing sleeves 12A, 12B-m-Magnetic roll 13--Standing control member 14-m-Agitation member 15.1
6.17---) Toner conveying member 20---Photosensitive drum

Claims (1)

[Claims] A developer comprising a developer carrier having inside thereof a magnetic roll in which a magnet related to development and a plurality of transport magnets for transporting the developer are arranged, and a spike regulating member for regulating the amount of spikes of the developer. A developing device characterized in that the regulating position of the bristling regulating member is set so as not to be caught by a repulsive magnetic field on an upstream side and a downstream side with respect to the rotating direction of the developer carrier.