JPS63155162A - Developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device for an electrophotographic copying machine, an electrostatic copying machine, etc., which visualizes an electrostatic latent image using a developer.

Conventional technology developing devices form an electrostatic latent image on a photoconductor or recording medium, bring a developer close to this electrostatic latent image, make the toner in the developer adhere, and visualize the electrostatic latent image. Transfer it to paper etc.
Fix and record.

The developers and development methods currently in practical use in developing devices include a one-component development method that uses a developer made of magnetic toner, and a one-component development method that uses a developer made of magnetic toner, and one that uses iron powder, resin particles in which magnetic material is dispersed, and resin-coated ferrite sintered particles. There is a two-component development method that uses a developer mixed with a magnetic carrier such as the above and a toner made of particles in which a coloring material is dispersed in a resin. -The component development method has the advantage of simplifying the structure of the developing device because it does not require toner concentration control, but it has the disadvantages of developing operations such as the complexity of stabilizing the toner charge and problems with image quality. Furthermore, for color image recording, magnetic toner is used to disperse the magnetic material, but there is a problem that the magnetic component development technique cannot be applied.

On the other hand, the two-component development method is widely put into practical use because of its advantages such as easy development operation, relatively good image quality, and fewer restrictions on the toner materials that can be used. However, the accuracy of the development gap and the developer amount regulation gap has a large influence on image quality not only for the negative component but also for the two components.

To maintain the accuracy of the developing gear knob, a spacer ring method is widely used in which rollers are placed at both ends of the magnetic roller and come into contact with the photoreceptor, and a structure that always provides a stable gap has been established. However, if the gear knob is wide, problems such as fogging on non-image areas and overtoning may occur, and if the gap is narrow, it may cause blurring (image blurring). There are problems with undertoner, etc.

Further, problems such as developer consumption and toner contamination from the developing device also occur. For this reason, various methods have been considered regarding the need to manage and fix the developer amount regulating gap using a jig or the like, and the material and shape of the blade.

Generally, the structure is such that a magnet roll is rotatably fixed to a frame that constitutes a developing device, and a blade is fixed to the frame while maintaining a constant gap. With this structure, in order to maintain the gap with a certain degree of accuracy, a member of the same size as the gear lug is sandwiched between the surface of the developing sleeve of the magnetic roller and the blade surface, the blade is fixed on top of that, and then the member is pulled out. Work is required. Even if a member of the same size as the gear knob is held in place, it will come out with good accuracy, but the dimensions will change if you pull it out after fixing it. In addition, a structure has been devised to achieve gear accuracy by keeping a member with the same size gap between the magnet roll and both ends of the blade, but since the member with the same size gap is in direct contact with the surface of the developing sleeve of the magnet roll, the member There were side effects such as dimensional changes due to wear and an increase in the torque of the developing sleeve of the magnetic roll. On the other hand, there is a method of measuring and fixing the gas knob in a non-contact manner, but this method has not been put to practical use because it is very difficult to measure the dimensions of the gear knob in a non-contact manner. As described above, although the accuracy of the developer amount regulating gap has a very large influence on image quality, an inexpensive and simple structure for ensuring stable accuracy has not been obtained.

Problems to be Solved by the Invention With the structure of the developer amount regulating gear as described above, there are cases where the operator relies on his or her senses due to differences in the amount of friction when inserting members of the same size, variations in the insertion angle, etc. In many cases, it is extremely unstable, and since members of the same size are sandwiched and fixed, there are problems in that the members wear out and the developing sleeve torque increases. In view of the above problems, the present invention provides a developing device having a structure that stabilizes the dimensional accuracy of the development amount regulating gap without complicating the structure of the developing device.

Means for Solving the Problems In order to solve the above problems, the present invention solves the above problems without complicating the structure of the developing device. It is equipped with a cylindrical bearing member that rotatably supports the magnet roller, and a blade that regulates the amount of spikes of the developer being conveyed. By keeping the blade in contact with the outer peripheral surface of the bearing member, the amount of developer can be adjusted. It has a configuration that improves the precision of the regulation gear and eliminates defects and variations in image quality.

According to the above-described structure, the center of rotation of the developing sleeve of the magnet roll 7) and the center of the cylindrical outer periphery of the bearing rotatably supporting the magnet roll coincide with each other.

Therefore, if the outer diameter of the bearing is set to the diameter of the developing sleeve of the magnetic roll plus the development amount regulation gap, the development amount regulation gear can be secured simply by touching both ends of the blade to the outer circumference of the bearing. Ru. The outer periphery of the bearing is cylindrical, so no matter which part of the bearing the blade contacts, an accurate gap is ensured. Even if the magnetic roll itself has a movable structure, the blade contacts the bearing that supports it. Gears can also be secured by providing means. Furthermore, even when the magnet roll rotates at high speed, there is no contact between the blade and the surface of the developing sleeve, so there is an advantage that there is no need to consider increases in friction and rotational torque. As described above, although the configuration is simple and inexpensive, stable images can be obtained by accurately maintaining the developer amount regulation gap. Although non-magnetic material is normally used for the blade, ferromagnetic material was used in order to widen the developer amount regulation gap as much as possible. If you use a magnetic blade, the magnetic field will block the flow of developer when the magnetic pole passes under the blade as the mag roll rotates, and the developer will flow only when the non-magnetized part of the magnet roll passes under the blade. You can pass under the blade.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

1 and 2 are cross-sectional views of a developing device in an embodiment of the present invention. Figure 1 shows a mode in which the developing sleeve and the magnet roll are both rotating, and the second
The figure shows a mode in which the developing sleeve is stopped and the magnet roll is rotating. FIG. 3 shows specific parts of an embodiment of the present invention. 1 and 2, 1 is a developing device housing, 2 is a developing sleeve, 3 is a magnet roll, 4 is a blade, 5 is a mesh member having a plurality of openings, 6 is a toner chamber, and 7 is a protective cover. , 8 is a toner stirring blade, 9 is a developer, and the developer 9 is a magnetic carrier 91.
and toner 92. Reference numeral 10 denotes a developer chamber, which is formed by the developing sleeve 2, the blade 4, and the mesh member 5. Reference numeral 11 denotes a photosensitive drum on which an electrostatic latent image is formed, and is formed by forming a photoconductive layer 13 on the surface of a conductive holder 12.

In addition, in Fig. 3, 14 is a bearing, and 16 is a bearing 1.
4 between the blade 4 and the developing sleeve 2.

The developing sleeve 2 is made of a cylindrical conductive non-magnetic material,
It has a magnet roll 3 inside, and the outer periphery of the magnet roll 3 is magnetized alternately with N and S poles. The developing sleeve 2 and the magnet roll 3 can each be rotated independently.

When developing the electrostatic latent image formed on the photosensitive drum 11, as shown in FIG. 1, the developing sleeve 2 is rotated in the direction of arrow a, and the magnet roll 3 is rotated in the direction of arrow The blade 4, which conveys the developer 9 in the direction of the arrow a to form a magnetic brush layer and perform development by rubbing against the electrostatic latent image, faces the surface of the developing sleeve 2 and is oriented in the direction of the developer conveyance. It is installed on the upstream side of the developing area, and the gear 15 between the blade 4 and the developing sleeve 2 is connected to the developing sleeve 2 as shown in FIG.
The brush height of the developer magnetic brush is regulated by bringing the blade 4 into contact with a cylindrical bearing 14 that rotatably supports the developer magnetic brush.

The blade 4 can be made of either magnetic or non-magnetic material. The net-like member ε extends parallel to the axial direction of the developing sleeve 2. The net member 5 may be woven from fibers or wires made of non-magnetic metal materials such as stainless steel, copper, and brass, magnetic metal materials such as steel and nickel, and organic polymer materials such as silk, nylon, and polyester. It may be formed by molding, punching, or etching, as long as it has a plurality of openings. The diameter of the opening of the net-like member 5 needs to be large enough for the developer, that is, the magnetic carrier, toner, and the magnetic carrier to which the toner is charged and adsorbed, to pass through. Generally used two-component developers have particle sizes ranging from 3 μm to 20 μm.
The toner is composed of a toner having a diameter of μm and a magnetic carrier having a particle size of 20 μm to 150 μm. Therefore, the opening diameter is 160μ
In order to maintain the pressure of the developer on the developing sleeve at m or more, that is, 100 mesh or less, it is desirable that the mesh is 9.2 or more (opening diameter 2 mm or less), and a mesh member with an open area ratio of 30% to 70% can be used. .

The toner agitating blade 8 has a function of rotating and agitating the toner 92 existing in the toner chamber 6 to increase the fluidity of the toner and sending the toner to the vicinity of the developer 9 . The protective cover 7 has functions such as preventing toner from scattering from the developer magnetic brush on the developing sleeve, and preventing foreign matter from entering the developer. The developing device housing 1 is made of an organic polymer material and a metal material base, and holds and fixes the above-mentioned developing sleeve 2, magnet roll 3, blade 4, net member 6, protective cover 7, and toner stirring blade 8, and also serves as a toner chamber. 6. The developer 9 is a mixture of a magnetic carrier 91 and a toner 92 in an amount necessary to form a magnetic brush layer on the developing sleeve 2, the developing sleeve 2, the blade 4, the mesh member 5, and the developing device housing 1. The amount is sufficient to fill the volume of the developer chamber 1Q, which is included in a part of the developer chamber 1Q.

The operation of the developing device constructed as described above will be described below with reference to FIGS. 1, 2, and 3.

By operating the developing device in a mode in which the developing sleeve 2 and the magnet roll 3 rotate together as shown in FIG. 1, it is possible to maintain the toner concentration of the developer within an appropriate range; This is not necessarily sufficient. Therefore, when the rotation of the developing sleeve 2 is stopped, which is operated in the mode shown in FIG. 2 in which the developing sleeve 2 is stopped and the magnet roll 3 is rotating, as necessary, the force of conveying the developer 9 by the developing sleeve 2 is lost. , since the developer 9 is easily transferred due to the rotation of the magnet roll 3,
The spikes of the developer 9 regulated by the blade 4 become high. That is, since the amount of developer flowing out from the blade 4 onto the developing sleeve 2 increases, the developer chamber 1o is
The amount of developer 9 decreases, and the pressure applied to the developer 9 in the developer chamber 1o decreases. Therefore, the developer 9 in the developer chamber 1o is easily transferred due to the rotation of the magnet roll 3, and the developer 9 that had formed a layer of magnetic brushes on the developing sleeve 2 when reaching the developer chamber 10 The developer is mixed and stirred again with the developer that had been stirred in the developer chamber 1o, and is made uniform. After passing through such a state, when the mode is switched again to the mode in which both the developing sleeve 2 and the magnet roll 3 are rotating, the toner concentration of the developer 9 on the developing sleeve 2 will be the same as that of the developing sleeve 2.
The result is more uniformity than in the case where the magnetic roll 3 is stopped and the magnetic roll 3 is not rotated.

Effects of the Invention As described above, the present invention includes at least a magnetic roller for conveying the developer, a cylindrical bearing member for rotatably supporting the magnetic roller, and a doctor blade for regulating the spikes of the conveyed developer. By abutting and maintaining the doctor blade on the outer circumferential surface of the bearing member, it is possible to improve the precision of the developer amount regulating gap and eliminate poor image quality and variations.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of the developing device in an embodiment of the present invention. FIG. 3 is a detailed view of a specific main part of an embodiment of the present invention, showing a state in which the sleeve is stopped and the magnet roll is rotating. 2...Developing sleeve, 3...Magnet roll, 4...Blade, 9...Developer,
14...Bearing member, 15...Developer amount regulation gap.

Claims (2)

[Claims] (1) At least a magnetic roller that conveys the developer, a cylindrical bearing member that rotatably supports the magnetic roller, and a blade that restricts the spikes of the developer that is conveyed, and the outer circumferential surface of the bearing member A developing device characterized in that a blade is brought into contact with and maintained in contact with the blade. (2) The developing device according to claim 1, wherein the blade is made of a magnetic material.