JPS58174971A - Developing device - Google Patents

Abstract

PURPOSE:To repulse a developer on a developer supporting body by its repulsing magnetic field, and to prevent it from advancing in the direction of a side member, by forming a magnetic field which repulses a magnetic field of a developer carrying magnet suitably provided in the developer supporting body, on both end parts of the developer supporting body. CONSTITUTION:When a notch groove 13A is provided on both end parts of a magnet 13 surrounded with a sleeve 12 for supporting a developer, a magnet in the direction of a side member 11A becomes a repulsing magnetic field forming magnet 131. By this repulsing magnetic field, a developer D on the sleeve 12 becomes unstable existing in the repulsing magnetic field forming part, and does not move in the direction of the side member 11A. It is prevented that the developer D leaks to the ouside and intrudes into the bearing part, by only making an elastic member 16 for preventing the leakage of a developer contact slightly, and also the developer is not accumulated not solidified on the elastic member, therefore, it is also prevented that elastic member 16 falls off.

Description

[Detailed description of the invention]

The present invention is a developing device used in an electrostatic recording device,
The present invention relates to a developing device that is improved to prevent developer from accumulating near both ends of the surface of a developer support or leaking to the outside. In an electrostatic recording device such as an electrophotographic copying machine or facsimile IJ, an electrostatic latent image of an image to be recorded is formed on a charge retaining member such as a photoreceptor or a dielectric, and this electrostatic latent image is transferred to an image containing toner. It is developed into a visible image using a developer. The device used for this development is a developing device, and various types of developing devices are currently known. FIG. 1 shows a developing device 1 known as a magnetic brush developing device. A drug support (referred to as a sleeve) 12 is provided so as to be rotatable in the direction of the arrow. Inside the sleeve 12, one main magnet 1- and a plurality of auxiliary magnets 13b are fixed to the magnet holder 14 with a slight distance from the sleeve. A part of the sleeve 12 is disposed close to the rotating drum 2, which has a charge holding member 2hk made of a dielectric material, on the surface of the photoreceptor 11 when the developing container 11 is opened, and this close position is the developing position. be. The upper part of the developer container 11 is provided with a spike regulation IIi, 15 that regulates the thickness of the developer layer conveyed to the development position by the sleeve 12, and the distance between the tip and the surface of the sleeve 12 is determined by the composition of the developer. It varies depending on the situation, but in one-component development that does not contain a carrier, it is usually 0. It is set at IIIJI~0.8. Now, when the sleeve 12 rotates, the internal auxiliary magnet group 13
Due to the magnetic action of b, the developer is attracted to the surface of the sleeve 12 and is fed, but the developer layer is regulated to a constant thickness by the spike regulating plate 15. When the developer approaches the position of the main magnet 3s, it stands up like a brush.The spikes of this brush-like developer slide against the surface of the charge retention member 2a.The toner in the developer is electrostatically charged on the charge retention member 2a. When a latent image is formed, toner is attracted to the electrostatic latent image by electrostatic attraction force, and the electrostatic latent image becomes a visible image.By the way, the developer used in this type of developing device includes:
Magnetic powder (carrier) such as iron powder and colored synthetic resin powder (
There are two-component developers, which consist of toner), and component-based developers, which consist of synthetic resin mixed with coloring material and magnetic powder.
Recently, the latter has started to attract attention due to reasons such as maintenance 7 Lee. Since the -a split thread developer does not contain a carrier, it consists only of crosslinkers whose particle size is smaller than that of a two-component developer. Therefore, the distance between the ear standing regulation plate 15 and the sleeve 12 is also 0.
．． The length is 5 m or less, which is smaller than the approximately 1 to 5 m for a two-component developer. Therefore, - modified thread developer has the property of being easily agglomerated, and since pressure is applied at the narrow regulating section, it is even more likely to agglomerate, and because the gap between the developing sleeve and the regulating plate is narrow, even the slightest agglomeration or dust can cause it to clump. There is a problem that clogging occurs and density unevenness occurs in the vertical direction. If developer clumps or dust are mixed in, the space between the spike control plate 15 and the sleeve 12 will become clogged, and the developer will not be transported to that area, preventing development from occurring (a white vertical line will appear on the copy). This problem is likely to occur. A phenomenon in which the developer sticks to the sleeve also occurs. These phenomena are particularly likely to occur when an insulating toner is used as a developer. As a result of experiments and studies, it has become clear that one of the causes of such aggregated toner and dust generation is from the vicinity of the side member that holds the developer and the developing roller. FIG. 2 shows a part of a sectional view of a developing roller of a conventional developing device and a side member of the developing device. In the figure, developer residue tends to accumulate at the end of the developing roller during development due to the spike control plate, stirring member, etc., and therefore developer residue leaks from between the side member 11A and the developing sleeve 12. In order to prevent this, leakage of toner is prevented by filling and fixing the spongy elastic member 16' in the concave portion of the side member 11A and making strong sliding contact with the outer periphery of the end of the sleeve 12. However, in such a configuration, a portion of the sliding surface of the elastic member 16 falls off due to friction caused by the rotation of the sleeve 12, and is mixed into the developer as dust. Alternatively, the developer particles that have entered between the sliding surfaces 12 and 16 and become clogged aggregate, and the coagulated mass is mixed into the developer in the developer container 11.Fragments of these elastic members, developer supports, etc. This is considered to be the main cause of the development defects mentioned above. Further, if the developer scum, fallen lumps, coagulated lumps, etc. enter the shaft end of the developing roller through the gap between the side member 11A and the sleeve 12, they will enter the bearings, gaps, etc., and cause the developing roller to rotate.

['The developer may leak outside and scatter, causing adverse effects. As mentioned above, the elastic member in the form of a stripe is insufficient and unsatisfactory as a means for preventing developer leakage. The present invention has been made in view of the above-mentioned problems.By providing a magnet for conveying developer in the sleeve and a magnetic pole that forms a repulsive magnetic field, the above-mentioned gap between the magnet and the side member is provided. This substantially solves l[. That is, a developer support that supports the developer to be transported to the development area, a developer transport magnet appropriately disposed within the developer support,
This is achieved by a developing device having repulsion field forming magnets that form a repulsion magnetic field in conjunction with the magnetic field of the conveying magnet at both ends of the developer support. As a result, the developer on the sleeve is repelled by the repulsive magnetic field and is prevented from moving toward the side member. The present invention will be explained below by showing specific examples thereof. FIG. 3 shows one shaft cylinder of an embodiment of the developing device of the present invention, and FIG. 3 shows lines of magnetic force in the repulsion magnetic field region in the configuration shown in FIG. This repulsive magnetic field makes it unstable for the developer on the sleeve 12 to exist in the recurrent magnetic field storage area.
1 *The developer hardly moves in the % direction, and the side member 1
By simply bringing the elastic member 16 for preventing developer leakage into slight contact with or close to the abutting portion with the sleeve 1A, leakage of developer to the outside of the developing device and intrusion into the bearing portion can be prevented. In this way, by the action of the repulsive magnetic field of the magnet 13 having the notched groove 13A, it is possible to prevent developer residue from accumulating and solidifying on the side member 11A and the elastic member 16 for preventing developer leakage. Elastic member 1 in sliding contact with 12
By reducing the contact pressure of the elastic member 16 to no or a small amount, it is possible to prevent the elastic member 16 from falling off. The above effects are achieved by the magnet contained within the sleeve 12], 3
Fixed sleeve 12rr: Not limited to rotating method.
Needless to say, it is possible to use either a system in which the enclosed magnet rotates and the sleeve is fixed, or a system in which both rotate. In addition, in the case of magnet fixation, the magnet 1 has the above-mentioned notch groove 13Arr at least in the magnet located under the spike regulating plate 15 that regulates the thickness of the developer layer of the sleeve 12-1:
The 3rt arrangement has a particularly remarkable effect because a large pressure is applied to the developer under the spike regulating plate 15. Next, FIG. 5 shows another embodiment, showing both ends 13B of the developing magnet 13 included in the sleeve 12, and an external magnet 17 provided on the side plate member 11A as a repulsion field forming magnet.
A repulsive magnetic field is formed by FIG. 6 shows the lines of magnetic force of the repulsion magnetic field caused by the magnets 13 B and +7 in FIG. 5. In FIG. 5, the outer magnet 17 is a part of the side plate member 11A, and is fixed at an alternative position to the elastic member 16 for preventing developer leakage, and is fixed inside both ends of the sleeve 12. A magnetic pole having the same polarity as the magnetic pole on the surface of the fixed magnet 13B is fixedly provided facing the direction of the fixed magnet 13B to form a repulsive magnetic field. Due to the action of this repulsive magnetic field, specifically, the developer is completely prevented from entering the gap between the external magnet 17 and the sleeve 12 due to the repulsive magnetic field between both N magnetic pole portions of the fixed magnet 13B1 and the external magnet 17. be done. Further, in this configuration, the fixed side member 11A
Between the external magnet 17 made of a rubber magnet or the like attached to the sleeve 12 and the rotating sleeve 12, there is no development failure caused by falling lumps due to friction, even without using the smegade-like elastic member or the like. Furthermore, developer residue does not accumulate on the inner wall of the side member 11A and form aggregates. Of course, by forming a strong repulsive magnetic field throughout the axial end of the circumferential surface of the sleeve or devising the shape of the engagement between the side member and the sleeve, even if a narrow space 11t is created between the two, the developer Leakage can be prevented. By using the developer scattering method using repulsive magnetic poles according to the present invention as described above, it is possible to avoid problems such as developer aggregation, development defects due to dust generation, and device failures due to developer leakage, which were problems in conventional developing devices. We have completely improved the environmental pollution caused by leakage and scattering of the agent, and have completed a useful developing device that can produce high-quality images. The above-mentioned developing device according to the present invention is particularly effective for one-component magnetic developers which are fine particles and easily coagulate, but can also be applied to two-component developers containing magnetic materials.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional developing device, FIG. 2 is a schematic sectional view taken along the axial plane of a developer support of the conventional developing device, and FIGS. 3 and 5 are a schematic diagram of a developing device according to the present invention. Schematic cross-sectional views taken along the axial plane of the developer support, FIGS. 4 and 6 show the magnetic force Ii near the repulsive magnetic field forming portion of the developing device according to the present invention.
1 is a diagram schematically showing I. 11...Developer container, IIA...Side member 12
... Sleeve 13 ... Magnet 13A ... Notch groove 13B ... Fixed magnet 14 ... Magnet holder 15 ... Ear standing regulation plate 16 ... Elastic member
17...External magnet D...Developer agent Yoshi Kuwahara Churato 1 1shi1 Saiichi

Claims (1)

Scope of Claims: (1) A developer support which is a developer support conveyed to a development area, a developer conveyance magnet appropriately disposed within the developer support, and a developer support member which is a developer support conveyed to a development area, (2) A developing device having a repulsion field forming magnet formed in part to form a repulsive magnetic field in addition to the magnetic field of the conveying magnet. Developing device according to scope 1. (3) The developing device according to claim 1, wherein the repulsion field forming magnet is fixedly installed outside the developer support. (4) The developing device according to any one of claims 1 to 3, wherein a leak prevention member for preventing developer leakage is provided in contact with the outer peripheral surface of the axial end portion of the developer support. (5) The developing device according to claim 4, wherein the repulsion field forming magnet is also used as the leakage prevention member.