JPS6257991B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing a charge pattern on an electrostatic image holding surface, and more particularly to a developing device using a powder developer, and a developer holding member of the device. The present invention relates to a developing device having a mechanism for preventing developer from scattering.

In general, developing devices using powder developer include:
Typical examples are the magnetic brush method and the cascade method, and the magnetic brush method includes a method that uses a developer consisting of a magnetic carrier and toner, and a method that uses toner that itself has magnetic properties. Especially in the latter development method using magnetic developer,
Since operations such as mixing carrier and toner are not required, the configuration of the developing device can be simplified compared to conventional powder developing devices. A developing device using the above-mentioned magnetic developer includes a hopper that stores the developer to be supplied, and a cylinder or cylinder that is located below the hopper so as to directly obtain the developer from the hopper, and that carries the developer on its surface. can be the main component. That is, the developer conveyance means is composed of a magnetic cylinder or a non-magnetic cylinder with magnetic means inside, and after holding the developer on the surface of the conveyance means, these magnetic cylinders or the outer non-magnetic cylinder The developed image is conveyed to an electrostatic image holding surface such as a photoreceptor by rotating the image forming apparatus or rotating the inner magnetic means to perform development.

Incidentally, the developing device using the magnetic developer described above has a simplified device configuration due to the principle of development, but these magnetic cylinders and non-magnetic cylinders (hereinafter simply referred to as conveying bodies for convenience) are used for conveying the developer. ), the force generated by driving the conveyance body, and the force caused by the pressure means to make the thickness of the developer applied to the conveyance body uniform, etc. Therefore, the developer was likely to be scattered from both ends of the conveying body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mechanism for preventing the developer from scattering from an end of the rotating conveyor in a developer conveyor that holds and conveys the developer as described above.

In order to achieve the above object, the present invention prevents the scattering of developer from the conveying body of a developing device that uses a magnetic powder developer such as a mixed developer containing a magnetic carrier and toner or a magnetic toner developer. It not only features a scattering prevention mechanism, but also has an area for development,
That is, the developer which has moved outside the development area on the surface of the conveying member corresponding to the development width of the electrostatic image holding surface is collected into the hopper and contributed to the development.

The structure of the present invention is to develop an electrostatic image using a magnetic powder developer stored in a hopper, so that the thickness of the developer layer on the conveyance surface of a conveyor that magnetically carries the magnetic powder developer is adjusted. In a developing device that carries out development by conveying the developer by a conveying member after regulating it with a developer thickness regulating member, the first invention represented by FIGS. , a sealing member for regulating the movement of the developer diffused toward the end in the axial direction of the conveying body; and a sealing member located inside the conveying body from the sealing member in the hopper and regulating the movement by the sealing member. The developing device is characterized in that the developing device is equipped with scooping members at both ends of the conveying body for scooping up the developer from the surface of the conveying body and collecting it in a developing area of the conveying body, A second invention represented by FIG. 6 regulates the movement of the developer that has been diffused toward the end in the axial direction of the conveying body, among the regulated developer, and also controls the movement of the developer toward the center of the conveying body. A developing device characterized in that a sealing member having a wall surface that guides and collects the developer whose movement is regulated in a protruding manner into a developing area of the conveying body is disposed in sliding contact at both ends of the conveying body. be.

Both the first and second aspects of the present invention remove and collect the developer in advance, which is a new cause of developer scattering that moves toward both ends of the conveying body and gradually accumulates. The anti-scattering effect can be achieved for a much longer period of time and more reliably than in the past. In particular, in the second invention, the scooping member of the first invention functions as the sealing member itself to collect the developer, so there is no boundary between the members, and a more stable prevention effect can be obtained.

With the above configuration, even if the developer moves in the direction of the rotation axis of the developer transport body and tries to scatter, the movement is first regulated by the sealing member, and furthermore, the developer is transported before being scattered by the scooping member. removed from the body. A preferred form for preventing the developer from scattering is that the conveying body, which is cylindrical in appearance, has a small diameter at both ends, and the conveying body having the small diameter and the sealing member are used to prevent the developer from scattering. A groove may be formed at the end of the carrier, and a scooping member may be disposed in the groove so as to mesh with the groove. With the above configuration, it is possible to clearly divide the peripheral surface of the conveyor into a necessary area that is actually used for development and an unnecessary area, and by removing the developer that has fallen into the groove, it is possible to sufficiently prevent the developer from scattering. . Furthermore, by using the groove, unnecessary developer that has fallen into the groove can be effectively removed by the scooping member without being affected by other components. In addition, by arranging the tip of the scooping member to engage with the groove,
The mounting state and operating state of the scooping member are also stabilized.

The developer removed from the conveyor by the scooping member is returned to the hopper and reused. Particularly, in the case of a developer without a carrier such as a magnetic developer, the developer does not get tired even when the developer is moved or stirred, so that the developer can be used effectively by being collected and reused. Note that the developer scattering described in the present invention is as follows:
This includes not only the case where the developer particles are scattered in a floating state in the air, but also the situation where the developer particles spread over the surface of the developer transporting member as they are transported. Also,
The conveyor of the present invention refers to a cylindrical magnetic means that directly holds the developer as described above, or a non-magnetic cylinder having a magnetic means inside. Regarding the latter carrier, there are those in which the non-magnetic cylindrical side rotates and the inner magnetic means is fixed, and those in which the cylindrical side is fixed and the inner magnetic means rotates.

Hereinafter, the present invention will be described in more detail with reference to embodiments and explanatory drawings.

FIG. 1 shows an image forming apparatus to which a developing device of the present invention is applied, and an electrophotographic copying apparatus is taken as an example. The figure shows the main parts of the copying apparatus. Reference numeral 1 denotes a photosensitive drum, which has a two-layer structure consisting of a conductive support and a photoconductive layer, and rotates in the direction of the arrow. Reference numeral 2 denotes a charger, and the surface of the photoreceptor is uniformly charged by the charger. 3 is an optical means that connects the drum 1 through the optical means.
An image is projected onto the surface of the drum 1, and an electrostatic image is formed on the surface of the drum 1 by the above-mentioned charging and projection. Next, the photosensitive drum 1 is developed by the developing device 4, and the developed image is transferred to the transfer section 5 and transferred to the paper feed section 6.
The image is transferred onto the transfer paper that has been conveyed. In the figure, 7 is a charger for transfer. After the above transfer, the transfer material is charged for separation by a charger 8,
While being conveyed by a conveyor belt, the sheet is heated and fixed by a fixing lamp 9, and is conveyed by a discharge roller 10 onto a tray 11 that is not attached. On the other hand, photosensitive drum 1
After the entire surface is exposed to light using a lamp 12 to eliminate static electricity, residual developer is removed by a cleaning device, and the sheet is prepared for the next copying cycle.

Next, the developing device of the present invention will be explained with reference to FIG. 2 and some related drawings. The cross-sectional view of the developing device 14 in FIG. 2 shows the developing device 4 of the device shown in FIG.
corresponds to In the figure, reference numeral 15 denotes a hopper, and a developer 16 made of insulating magnetic toner for supply is stored in the hopper 15, and the upper part is covered with a lid 17. On the other hand, the above hopper 1
The lower part of the hopper 5 is open to face the non-magnetic developing sleeve 18 constituting the conveying body, and the developer 16 is supplied to the conveying body from this open part at the lower part of the hopper. The sleeve 18 is rotating at the same speed as the circumferential speed of the photosensitive drum 1 in the direction of the arrow. A permanent magnet 19 having a plurality of magnetic poles arranged on its circumferential surface is fixedly provided inside the sleeve 18 . The principle of conveyance of the developer is based on the sleeve 18 mentioned above.
Due to the rotation of the sleeve 18 and the action of the magnet 19, the sleeve 18
The developer placed on the sleeve 18 is conveyed as the sleeve 18 rotates. Of course, contrary to this, it is possible to convey the developer even if the sleeve 18 is fixed and the magnet 19 is rotated.

By the way, in the developing device 14 equipped with the scattering prevention mechanism of the present invention, the developer supplied onto the sleeve 18 from the hopper 15 first passes through the hopper 1.
5. The fixed blade 20 integrally formed at the lower part of the film is applied in a manner that regulates the thickness to be constant. The fixed blade 20 serves not only to keep the thickness of the developer applied to the sleeve 18 constant, but also to prevent large lumps of developer from being applied to the surface of the sleeve 18. The developer layer on the sleeve 18 is then uniformly compressed by an elastic blade 21 in order to make the thickness of the developer layer more uniform and thinner. This elastic blade 21 has a flexible elastic blade 21a made of rubber, synthetic resin, etc. on the sleeve side, and a spring member 21b made of a thin steel plate provided in close contact with the back surface of the elastic blade 21a. One end of the blade 21 is connected to the hopper 1
5 is locked with a screw 22. By adjusting the configuration of the blade 21 so that a pressure of 0.4 to 40 g is applied per 1 cm in the longitudinal direction of the sleeve 18, the thickness of the developer layer can be formed into a uniform layer of 50 μm or less. In particular, by making the blade 21 a double structure of elastic steel plates, even if a lump of developer gets into the position of the blade 21, due to the appropriate elasticity and steel properties,
This lump can be crushed to form a uniform developer layer of 100 μm or less without affecting the surrounding developer or sleeve.

The developer layer formed to a thickness of about 50μ by the elastic blade 21 is attracted by the charge of the electrostatic image formed on the surface of the photosensitive drum 1 at a position facing the photosensitive drum 1 in the gap b, and the electrostatic image It is adsorbed to the part. The gap b is about 0.1 mm, which is set larger than the gap a formed between the fixed blade 20 and the sleeve 18. The developer that does not actually contribute to development at the development position is stored in the sleeve 18.
While being attracted to the top, the developer reaches the developer supply section of the hopper 15 again.

By the way, after the developer is applied to the rotating body such as the sleeve 18 that conveys the developer as described above, the developer layer is stroked or pressurized again to make the thickness of the developer uniform. In this case, the developer is diffused in the axial direction of the conveyor such as the sleeve due to the action of these blades 21 and the like. If this diffusion phenomenon continues, the developer reaches a position where the magnetic force of the conveyor does not reach, and the developer eventually falls from the conveyor and contaminates the photosensitive drum and surrounding components. Examples of countermeasures to solve this problem include providing convex portions at both ends of the conveyor, or providing a sealing material to restrict the spread of the developer. However, even with these measures in place, developer that spreads outside the developing area accumulates and solidifies near the sealing material, etc., and becomes load resistant to the rotational force of the rotating body. The developer that continues to spread and spread will eventually accumulate in large quantities near the sealing material, so it may move toward the axial end of the conveyor and overcome the sealing material. is expected. The present invention solves these problems in the developing device, and an embodiment thereof will be described with reference to the drawings from FIG. 3 onwards.

FIG. 3 is a sectional view taken along the line - in FIG. 2, and FIG. 4 is a sectional view taken along the line - in FIG. This is what is shown. In Figure 3, hopper 1
The toner 16 stored in the sleeve 5 is supplied toward the back of the figure through a gap a defined by the surface of the sleeve 18 and the fixed blade 20. Note that there are portions 18a with a reduced diameter at positions on both ends of the sleeve 18 that are not used for development. The developer on the sleeve stroked by the second blade 21 falls onto the recess 18a of this sleeve.
Since the magnetic force of the magnet 19 also acts in this recess 18a, the developer is transferred to the recess 18a of the sleeve.
It is transported while being held on top. By the way, a sealing material 23 made of felt, sponge, etc. is provided around the entire circumference of the sleeve recess 18a.
The sealing material 23 of this embodiment is fixed to the container side of the developing device with an adhesive. Therefore, even if the sleeve 18 rotates, the sealing material 23 does not rotate.
The developer that has fallen into the groove formed by the recess 18a and the sealing material 23 reaches the supply section from the position of the elastic blade 21 while sliding or rotating on the sleeve 18. At this time, the developer on the sleeve groove gradually spreads toward the sleeve end as it moves due to conveyance. The developer on the groove 18a of the sleeve that has reached the initial supply section is
Shoulder portions (convex portions) of the sealing material 23 and sleeve 18
It is collected into the hopper 15 by a scooping member 24 disposed so as to mesh with the hopper 15. The scooping member 24 is made of a metal piece, an elastic blade, or the like, and is fixed to the surface of the fixed blade 20 of the hopper 15 by a locking member 25 such as a screw. The elastic blade 21 is in planar contact with the rotation of the sleeve, and the scooping member 24 and the fixed blade 20 are connected to the sleeve 18.
is arranged in the opposite direction to the rotation of. Therefore, the developer that has fallen into the groove reaches the scooping member 24 while being held in the groove by the shoulder of the sleeve 18 and the sealing material 23. The toner in the groove is scooped up by the scooping member 24, collected into the hopper 15, and applied to the sleeve 18 again. Note that since the sealing material 23 and the sleeve 18 rub each other, the toner that has fallen into the groove does not pass under the sealing material 23 and diffuse to the outside of the sealing material.

In the figure, 26 is a driving gear, and 27 is a hollow connecting rotary body, which connects the gear 26 and the sleeve 18, and the gear 26 is fixed to the rotary body 27 by a pin 28. A ball bearing 29 is provided between the container of the developing device 14 and the rotating body 27.
On the other hand, ball bearings 30 and 31 are disposed between the fixed shaft of the magnet 19 and the rotating body around the fixed shaft, and the left end of the magnet (see FIG. 3)
It is fixed to a part of the developer container by a pin 32. With the above configuration, the sleeve 18 is driven by the rotation of the gear 26, and the magnet 20 is fixed against the rotation of the sleeve 18.

Next, the sealing material 23 will be explained with reference to FIG. The figure shows a state in which the end portion of the sleeve 18 and the sealing material 23 are expanded along the periphery of the sleeve 18. In the figure, area A on the sleeve 18 shows the area where the elastic blade 21 acts, and area B shows the area where the fixed blade 20 acts. As shown in the figure, the excess developer falls into the groove 18a due to the stroking action of the elastic blade 21, and moves in the direction of the arrow while spreading slightly as the sleeve 18 rotates. The developer in these grooves 18a is eventually guided by the wall surface of the sealing material 23 and reaches the scooping member 24. At this position of the scooping member 24, the developer in the groove rides on the scooping member 24 by the shoulder of the sleeve 18 and the wall of the sealing material 23, and the scooped up developer is guided into the hopper 15. Although FIG. 5 discloses a configuration in which the wall of the sealing material 23 gradually becomes narrower with respect to the scooping member, the present invention is not limited to this, and a groove portion may be formed in the width of the scooping member over the entire circumference.

With the above configuration, the developer that spreads in the axial direction of the conveyor such as the sleeve does not spread beyond the regulated width, and furthermore, the spread developer is collected and reused by the scooping means, making it economical. It is. Further, the above configuration makes it possible to apply appropriate means on the conveying body in order to make the developer on the conveying body uniform or to make it extremely thin (thickness 100 μm or less). In the embodiment shown in FIG. 2, an elastic blade is used as this appropriate means, but in other cases, a rotating roller or the like can be used.

FIG. 6 shows a modification of the sealing material 23 shown in FIG. 5, which is a second embodiment of the present invention. As can be understood from FIG. 6, the protrusion 33a located at the end in the axial direction of the conveyor is the seal member 23 itself, and as described above, the developer guide wall surface of the protrusion 33a guides the developer as shown by the arrow. The toner is collected within the area necessary for development of the conveying body, that is, in the hopper on the center side of the conveying body. The other structure of this sealing member is the same as that shown in FIG. 5, as can be understood by comparing the figures. The illustrated sealing material 33 is fixed to the container side like the sealing material 23 described above, and a portion 33a thereof protrudes into the groove 18a so that the developer is collected into the hopper 15. In other words, the fifth
As can be understood by comparing Figure 6, the protrusion 3 in Figure 6
It can be seen that 3a acts as the scooping member in FIG. Even in this manner, the developer can be collected into the hopper.

Regarding the configuration of the sealing material mentioned above, we have described a type that slides on a conveyor such as a sleeve, but
As another example, as shown in FIG.
4 is fixed to the carrier 35, and the carrier and the sealing material 3
A scooping member 36 may be disposed in the groove portion 35a having a constant width formed by the groove portion 35a. Furthermore, the sealing material may be provided on the same plane as the carrier without providing the groove. In addition, although the above-mentioned sleeves up to FIG. 7 are described as rotating ones, it is of course possible to fix the sleeve side and rotate the magnet side disposed inside the developing device of the present invention. The chemical scattering prevention device works effectively. Note that the developing device of the present invention is particularly effective for a type of developing device that strokes the developer on a developer holding member such as a sleeve. It is also effective for a developing device that acts on the agent and a developing device that has a web-like conveyor. As for the developer, any developer can be used as long as it is supported on the conveyor by magnetic force as described above, so the present invention can also be applied to a developer that also has the carrier described above.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a copying apparatus incorporating the developing device of the present invention, FIG. 2 is a sectional view of an embodiment of the apparatus, FIG. 3 is a sectional view taken along the line -- of the apparatus of FIG. Fig. 2 is a sectional view taken along the line - Fig. 5 is a partially exploded view of the sleeve and sealing material, Fig. 6 is an exploded view of another embodiment of the sealing material, and Fig. 7 is a developer conveyance diagram showing another embodiment. A front view of the body end is shown. In the figure, 1...
Photoreceptor, 14...Developing device, 15...Hopper,
18... Sleeve, 20, 21... Blade, 2
3... Sealing material, 24... Scooping member, 33
... Sealing material, 36 ... Scooping member.

Claims (1)

[Claims] 1. In order to develop an electrostatic image using a magnetic powder developer stored in a hopper, the thickness of the developer layer on the conveyance surface of a conveyor that magnetically supports the magnetic powder developer. In a developing device that performs development by transporting the developer by a conveying body after regulating it with a developer thickness regulating member, the developer after the regulation is diffused toward the end in the axial direction of the conveying body. a sealing member for regulating the movement of the developer, which is located inside the transporter than the sealing member in the hopper, and scoops up and transports the developer whose movement is regulated by the sealing member from the surface of the transporter. A developing device comprising scooping members at both ends of the conveying body for recovering the body into a developing area. 2. The sealing member has a wall surface that guides the developer and rubs against the conveying body, and the wall surface gradually faces toward the center of the conveying body toward the scooping member. Developing device according to item 1. 3. In order to develop an electrostatic image using the magnetic powder developer stored in the hopper, the developer thickness regulating member controls the thickness of the developer layer on the conveying surface of the conveying body that magnetically carries the magnetic powder developer. In a developing device that performs development by transporting the developer by the transport body after being regulated by the transport member, the movement of the developer that is diffused toward the end in the axial direction of the transport member, of the developer after the regulation is controlled. A sealing member having a wall surface that restricts the movement of the developer and guides and collects the developer that protrudes toward the center of the conveyor into a developing area of the conveyor is slid onto both ends of the conveyor. A developing device characterized in that: 4. According to claim 3, in the sealing member, a wall surface located upstream from the protruding wall surface in the developer transport direction gradually faces toward the center of the conveying body toward the protruding wall surface. developing device.