JP4162350B2 - Magnet roller, magnetic brush carrier roller, magnetic brush carrier roller built-in device, image forming apparatus, and magnet roller shaft member removing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnet roller provided with a plurality of magnets, a developing roller having the magnet roller and forming a magnetic brush on the surface, a cleaning roller or charging roller, a developing device including the roller, a cleaning device, and a charging device. The present invention relates to an apparatus for capturing a developer for preventing carrier scattering and an image forming apparatus equipped with at least one of these apparatuses.
[0002]
[Prior art]
In general, in an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine, a printer, or a facsimile, the surface of a latent image carrier composed of a photosensitive drum or a photosensitive belt is uniformly charged and then the surface is An electrostatic latent image corresponding to the image data is formed, and a developing operation is performed by the developing device, a visible image is obtained, and the visible image is fixed to form an image on a recording medium such as recording paper. It has become. At that time, in executing the developing operation, a magnetic brush developing system using a two-component developer composed of a toner and a carrier from the viewpoints of transferability, halftone reproducibility, and stability of development characteristics with respect to temperature and humidity. Is becoming mainstream. That is, in the developing device, the two-component developer rises in a brush chain shape on the developer carrying member, and in the developing area, the toner in the developer is supplied to the latent image portion on the latent image carrying member. . Here, the development region is a range where the magnetic brush rises on the developer carrier and is in contact with the latent image carrier. It is also known to form a magnetic brush for charging or cleaning when the latent image carrier is uniformly charged or when the surface of the carrier is cleaned after transfer.
[0003]
By the way, in the case of an image forming apparatus, if it is used for a long period of time, maintenance work such as replacement of a photosensitive drum or the like, supply or replacement of a developer or toner, or adjustment, cleaning, or replacement of a charging device or a cleaning device is performed. Is required. However, such maintenance work is generally performed by a service person having specialized knowledge. As a result, the user may be inconvenienced.
[0004]
Therefore, in order to eliminate such inconvenience, a process cartridge in which image forming process means such as a photoreceptor, a developing device, and a cleaning device are integrated as a unit has been commercialized. By using such a process cartridge, the user can easily perform maintenance and replacement by himself / herself when maintenance is required for the image forming process means, and high-quality image quality can be continuously obtained. It came to be able to.
[0005]
On the other hand, a developing roller or the like is provided in the developing device of the process cartridge in order to visualize the latent image on the photosensitive member. A sleeve (development sleeve) that is usually formed in a cylindrical shape is provided, and a magnet body (magnet roller) that forms a magnetic field is provided inside the sleeve so as to cause rise of the developer on the sleeve surface. In a magnet roller formed by forming a magnet that forms a plurality of magnetic poles in a bar shape, a magnet and a shaft member that supports the magnet are fixed by integral molding, adhesion, press-fitting, or the like.
[0006]
In the above fixing method by bonding, the adhesive is uniformly applied to the outer peripheral surface of the shaft member that supports the magnet, the magnet is attached to the outer surface to which the adhesive has been applied, and stored in an environment where the temperature and humidity are kept constant, The adhesive is completely cured. In addition, as an adhesive agent to be used, an instantaneous adhesive agent, an adhesion primer, an anaerobic adhesive agent, etc. are mainly used, and it is properly used according to the use, purpose, required strength, etc. In the integrally molded product, when the shaft member and the magnet portion are formed, a magnetic material is molded into the mold by injection molding or the like. Further, in the press-fitted product, a magnetic material extruded into a cylindrical shape (bamboo ring shape) is softened by heat, and a shaft member that supports a magnet is press-fitted into the inner space to form a magnet roller.
[0007]
[Problems to be solved by the invention]
However, the integral molding, bonding, and press-fitting configurations have the following problems. That is, when the developing roller is reused, the deformed and worn parts themselves must be replaced or their surface properties must be restored by a mechanical or chemical method. Therefore, the magnet roller, gear, flange, and sleeve are disassembled and separated, and the corresponding member is replaced with a new one according to the amount of deformation and wear, or processed so that it can be reused using a mechanical or chemical method. There is a need to. However, in the fixing method using an adhesive, it is difficult to separate the magnet and the shaft member that supports the magnet without causing deformation. The same applies to the press-fitting joining method. In the integral molding, separation / disassembly is not originally assumed. Therefore, the magnet roller, and hence the developing roller, is not reused and has been discarded.
[0008]
Further, the shaft member that supports the magnet is constantly in contact with the flanges at both ends in the longitudinal direction that support the developing sleeve, and is rubbed and worn with time by a slide bearing or a ball bearing inserted into the flange. When the shaft member that supports the magnet is worn, the deflection accuracy of the outer periphery of the developing sleeve is lowered, and therefore, the amount of developer pumped up varies, causing problems such as abnormal images and carrier scattering. Therefore, it is difficult to reuse the magnet roller itself depending on the wear amount of the shaft member that supports the magnet.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a magnet roller capable of reusing a permanent magnet, a magnetic brush forming roller incorporating the magnet roller, and an apparatus including the magnetic brush forming roller.
[0010]
[Means for Solving the Problems]
According to the present invention, in the magnetic brush forming roller according to the present invention, the magnet roller fixedly disposed in the nonmagnetic sleeve is formed so as to be separable between the magnet portion having the magnet holding member and the shaft member supporting the magnet portion. In the magnet roller, the shaft member penetrates the magnet holding member, and an outer peripheral surface of the shaft member is provided with a protruding shape capable of making a one-way insertion / extraction direction. When removing the shaft member, the shaft member can be removed by pushing or pulling out the shaft member in the one-way insertion direction .
[0011]
It is preferable that the shaft member is provided with a notch or a protrusion in the range of insertion into the magnet portion, and a hole having a shape corresponding to this is provided on the end surface of the magnet portion . The shaft member may penetrate the magnet holding member, and may be fixed by a pin member after the shaft member is inserted into the magnet holding member.
[0012]
Examples of the apparatus provided with the magnetic brush forming roller include a developing device, a cleaning device, a charging device, and a developer capturing device for preventing carrier scattering.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described based on examples shown in the drawings.
First, the entire photosensitive unit including the developing device according to the present invention will be described. Although a developing device will be described as an example of the subject of the invention, it should be understood from the above description that a cleaning device or a charging device may be used as long as a magnetic brush is formed on the peripheral surface. I must. In FIG. 1, around a photosensitive drum 1 as a latent image carrier, there are a charging device 2 for charging the drum surface, an exposure 3 made of a laser beam for forming a latent image on a uniformly charged surface, A developing device 4 that forms a toner image by attaching charged toner to the latent image on the drum surface, a transfer device 5 that transfers the toner image on the formed drum to the recording paper 6, and residual toner on the drum is removed. A cleaning device 7 for removing the charge and a charge eliminating lamp 8 for removing the residual potential on the drum are arranged in this order. In such a configuration, the photosensitive member 1 whose surface is uniformly charged by the charging roller of the charging device 2 forms an electrostatic latent image by the exposure 3 and forms a toner image by the developing device 4. The toner image is transferred from the surface of the photosensitive drum 1 to a recording sheet conveyed from a paper supply tray (not shown) by a transfer device 5 including a transfer belt. The recording paper that electrostatically adheres to the photosensitive drum during the transfer is separated from the photosensitive drum 1 by the separation claw. The toner image on the unfixed recording paper is fixed on the recording paper by the fixing device. On the other hand, the toner remaining on the photosensitive drum without being transferred is removed and collected by the cleaning device 7. The photosensitive drum 1 from which the residual toner has been removed is initialized by the charge eliminating lamp 8 and used for the next image forming process.
[0014]
The configuration of the developing device 4 will be described with reference to FIG. In the developing device 4, a developing roller 41, which is a developer carrying member, is disposed so as to be close to the photosensitive drum 1, and a developing area where the photosensitive drum and the magnetic brush are in contact with each other is provided. Is formed. In the developing roller 41, a developing sleeve 43 formed of a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is rotated in a clockwise direction by a rotation driving mechanism (not shown). . In this embodiment, the drum diameter of the photosensitive drum 1 is 60 mm, the drum linear speed is set to 240 mm / second, the sleeve diameter of the developing sleeve 43 is 20 mm, and the sleeve linear speed is set to 600 mm / second. . Therefore, the ratio of the sleeve linear velocity to the drum linear velocity is 2.5. The development gap, which is the distance between the photosensitive drum 1 and the development sleeve 43, is set to 0.4 mm.
[0015]
A doctor blade 45 that regulates the height of the developer chain spike, that is, the amount of developer on the developing sleeve, is installed on the upstream side of the developing area in the developer transport direction (clockwise as viewed in the figure). ing. The doctor gap, which is the distance between the doctor blade 45 and the developing sleeve 43, is set to 0.4 mm. Further, a screw 47 for pumping up the developer in the developing casing 46 to the developing roller 41 while stirring the developer is provided in a region opposite to the photosensitive drum of the developing roller.
[0016]
In the developing sleeve 43, a magnet roller body (magnet roller) 44 that forms a magnetic field is provided in a fixed state so as to cause the developer to rise on the peripheral surface of the developing sleeve 43. The developer carrier rises in a chain shape on the developing sleeve 43 so as to follow the normal direction magnetic line of force generated from the magnet roller body, and the charged toner adheres to the carrier that has the chain shape. Thus, a magnetic brush is configured. The magnetic brush is transferred in the same direction as the developing sleeve 43 (clockwise as viewed in the figure) by the rotation of the developing sleeve 43. The magnet roller body 44 includes a plurality of magnetic poles (magnets). Specifically, the developing main magnet P1b that causes the developer to rise in the developing region, the main magnetic pole magnetic force forming auxiliary magnets P1a and P1c for assisting the magnetic forming of the main magnetic pole, and the developer sleeve 43 for pumping up the developer. A magnet P4, magnets P5 and P6 for conveying the pumped developer to the development area, and magnetic poles P2 and P3 for conveying the developer in the developed area. These magnets P1b, P1a, P1c, P4, P5, P2 and P3 are arranged in the radial direction of the developing sleeve 43. In this example, the magnet roller body 44 is composed of 8-pole magnets. However, in order to improve the pumping performance and black solid image followability, the number of magnets (magnetic poles) is further increased between the P3 pole and the doctor blade 45. You may comprise 10 poles or 12 poles.
[0017]
As can be understood from FIG. 2, the developing main pole group P1 is composed of magnets having small cross sections arranged in the order of P1a, P1b, and P1c from the upstream side. These magnets having a small cross section are made of a rare earth metal alloy, but samarium alloy magnets, particularly samarium cobalt alloy magnets, can also be used. Among rare earth metal alloy magnets, a typical iron neodymium boron alloy magnet has a maximum energy product of 358 kJ / m ³ , and an iron neodymium boron alloy bonded magnet has a maximum energy product of around 80 kJ / m ³ . Unlike conventional magnets, such a magnet can ensure the required developing roller surface magnetic force even if the size is considerably reduced. In the conventional ordinary ferrite magnets or ferrite bond magnets maximum energy product each 36 kJ / ^{m 3} before and after a 20 kJ / ^{m 3} before and after. When it is acceptable to increase the sleeve diameter, it is possible to reduce the half-value width by increasing the shape using a ferrite magnet or ferrite bonded magnet, or by forming the tip of the magnet facing the sleeve side narrowly. Is possible. In this embodiment, the magnet is formed by a magnet having a small cross section, but may be formed by a magnet roller formed by integral molding. Further, magnets other than the P1 pole group are first integrally molded and the P1 pole group is individually formed. May be formed integrally or simultaneously.
[0018]
In this example, the developing main magnet P1b, the magnet P4 for pumping up the developer onto the developing sleeve 43, the magnet P6 for transporting the pumped developer to the developing area, and the developer in the post-development area. The magnetic poles P2 and P3 form an N pole, and the main magnetic pole magnetic force forming auxiliary magnets P1a and P1c that assist the magnetic formation of the main magnetic pole and the magnet P5 that conveys the pumped developer form an S pole. As the main magnet P1b, a magnet having a normal magnetic force of 85 mT or more on the developing roller was used. The magnetic force related to carrier adhesion is tangential magnetic force, and in order to increase this tangential magnetic force, it is necessary to increase the magnetic force of P1b, P1a, and P1c, but suppressing the occurrence of carrier adhesion by increasing any one sufficiently. Can do. The magnet width of the magnets P1b, P1a, and P1c was 2 mm. At this time, the half width of P1b was 16 °.
[0019]
As an example (second example) of a magnet roller body having another magnet arrangement, FIG. 3 shows an arrangement configuration in which no auxiliary magnetic pole is provided on the upstream side or the downstream side of the main magnetic pole. Except for the magnet arrangement of the magnet roller body, the configurations of the developing device 4 and the photosensitive drum 1 are the same as those shown in FIG. The magnet roller body 44 ′ includes a developing main magnet P1 for causing the developer to sprout in the developing area, a magnet P4 for pumping the developer on the developing sleeve 43, and a magnet P5 for conveying the pumped developer to the developing area. P6 includes magnetic poles P2 and P3 for conveying the developer in the developed area. These magnets P 1, P 4, P 5, P 2 and P 3 are arranged in the radial direction of the developing sleeve 43. In the second example, the magnet roller body 44 ′ is composed of a 6-pole magnet. However, as in the above example, in order to improve the pumping performance and the black solid image followability, the gap between the P3 pole and the doctor blade 45 is increased. Further, the number of magnets (magnetic poles) may be further increased to constitute 8 or more poles.
[0020]
Similar to the above example in which auxiliary magnets are provided on the upper and downstream sides of the main magnet, the main magnet P1 forming the developing main pole is composed of a magnet having a small cross section. The magnet having a small cross section is made of a rare earth metal alloy, but a samarium alloy magnet, particularly a samarium cobalt alloy magnet, can also be used. When it is permissible to increase the sleeve diameter, it is possible to narrow the half-value central angle by using a ferrite magnet or a ferrite bonded magnet to make the tip of the magnet thin toward the sleeve side.
[0021]
In the second example, a magnet P4 for pumping the developer onto the developing sleeve 43, a magnet P6 for transporting the pumped developer to the development area, and magnets P2 and P3 for transporting the developer in the developed area are provided. The N pole is formed, and the developing main magnet P1 and the magnet P5 for conveying the pumped developer form the S pole.
[0022]
A mounting structure of the developing roller 41 including the magnet roller bodies 44 and 44 'having the magnet arrangement as described above will be described with reference to FIG. In this figure, a doctor blade 45 is integrally formed with a gap between the blade and the roller so that a necessary pumping amount can be obtained via the developing roller 41, the screw 11 and the support plate 12 during development. ing. The developing roller 41 includes flange members (front and rear flanges) 13 and 14 at both ends in the longitudinal direction, a developing sleeve 43 closed at both ends by these flange members, and a magnet roller body 44 (denoted by reference numerals) accommodated in the developing sleeve 43. For the sake of simplicity, the reference numeral 44 is assumed to include a second magnet roller body 44 ′). In the front and rear flanges 13 and 14, a sliding bearing 15 is inserted in a low-speed developing device, and a ball bearing is inserted in a medium- and high-speed developing device, and slides with a shaft piece supporting a magnet. . In the developing process, the developing roller is rotationally driven by a driving source (not shown) from the left side (rear side of the apparatus) via a transmission means such as a gear or a coupling. While the magnet roller 44 is fixed to the support plate 12 on the right side in the drawing by a front shaft piece so as not to rotate, the developing sleeve 43 is supported by another bearing 16 incorporated in the rear support plate 12. After that, the developer rotated with the rotation of the flange 14 and pumped up to the outer peripheral surface is supplied to the developing area. At this time, the developing sleeve 43 rotates around the bearing 15 inserted in the front and rear flanges 13 and 14, and the surface of the shaft piece that contacts the bearing 15 is worn by rotational sliding.
[0023]
In FIG. 5, a magnet roller body 44 according to the present invention comprises a plurality of magnets (not shown), a holding member 21 that holds these magnets, and front and rear shaft members 22 and 23 that support the holding member. When the shaft members 22 and 23 corresponding to the shaft piece in contact with the bearing in the description are worn and become unusable, the shaft member can be removed from the magnet roller body and replaced with a new shaft member. .
[0024]
As described above, the magnet roller is fixed in a non-rotatable manner in the developing device, and a relative position with respect to the photosensitive member and the developing device internal member, such as a doctor position, a pumping position, a developer separating position, etc. is determined. Therefore, it is not necessary to simply replace the shaft member. Therefore, as shown in FIG. 6, notches 26 and 27 are formed on the shaft members 22 and 23 to be replaced so as to correspond to the shapes of the holes 24 and 25 of the magnet holding member fitted to the shaft members. It is formed. As a result of this notch, the cross section of the part has a D shape. The notches of the holes 24 and 25 to be fitted and the shaft members 22 and 23 may support the roller body so that the magnet roller body does not rotate, and various kinds such as a square, a star, a triangle, an oval, a long hole, etc. The shape can be taken. Since the shaft member having such a notch cross section is fixed to the support plate of the developing device so as not to rotate, a notch 28 is also formed on the opposite side of the notch 26 of the shaft member 22. .
[0025]
Another shape configuration of the shaft member is shown in FIGS. As schematically shown in FIG. 7, a claw piece 31 is formed on the shaft member 23 ′. The claw piece 31 may be formed by tearing the shaft member 23 ', or may be formed by additionally attaching a separate piece. By attaching a key groove to the hole of the holding member 21 so as to correspond to the claw part piece 31, the claw part piece 31 bites into the key groove and does not come out, so that the shaft member 23 ′ with respect to the holding member 21 Rotation is prevented. Although the formation of the claw member has been described on the side of the rear shaft member, it is naturally applicable to the front shaft member.
[0026]
FIG. 8 shows an example in which a suitable number of one-way projections 34 are formed on the outer peripheral surface of the shaft member 33 that passes through the holding member 21 ′ that holds the magnet. A shaft member notch for allowing the shaft member to be non-rotatably fixed to the support plate of the developing device is not shown. The protrusion 34 is disposed in a region corresponding to the range of the holding member 21 ′ and engages with a recess 35 formed on the inner peripheral surface of the holding member 21 ′. The worn shaft member is taken out, and the exchange shaft member is inserted from the opposite side to improve exchangeability. It is guaranteed that the relationship between the support plate positioning surface, the shaft positioning surface, and the magnet pattern does not collapse so that the engagement position between the protrusion and the recess does not change depending on the angular position of the shaft member into which the magnet magnetic force distribution pattern is inserted. Of course, it must be decided to be done.
[0027]
7 and 8, the claw member is an elastic protrusion, the protrusion is a claw part, or a groove or a recess is formed on the shaft member side, and the claw or protrusion is provided on the holding member side. You may do it.
[0028]
FIG. 9 shows an example in which both the members are fixed using the positioning pins 37 after the shaft member 36 is fitted to the magnet holding member 21. In this case, the positioning pin mounting position should not be on the developing main magnetic pole side and should be a place that does not affect image formation. The pin may be a screw, a split pin, or the like, as long as it has a shape or method that can be easily replaced. For example, if the member for fixing these magnets is provided in the very vicinity where the developer is separated, it is possible to make the image particularly difficult to influence.
[0029]
In the above description, the magnet roller is described as for the developing device, but it can also be used as an electrophotographic cloning roller using magnetic toner or the like, and also prevents carrier scattering provided on the downstream side of the developing device. It can also be applied to a developer capturing magnet roller.
[0030]
【The invention's effect】
According to the present invention, the magnet roller fixedly arranged in the non-magnetic sleeve is formed so as to be separable between the magnet portion and the shaft member supporting the magnet portion. Even if it becomes necessary, the magnet part can be used repeatedly by replacing only the shaft member.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a photoconductor unit including a developing device according to the present invention.
FIG. 2 is a detailed configuration diagram of the developing device in FIG. 1;
FIG. 3 is a detailed configuration diagram of a developing device including a magnet roller body having another arrangement configuration.
FIG. 4 is a plan view schematically showing a mounting structure of a developing roller including a magnet roller.
FIG. 5 is a schematic view illustrating that a shaft member can be separated from a magnet holding member.
FIG. 6 is a conceptual diagram illustrating a configuration example of a separable shaft member.
FIG. 7 is a conceptual diagram showing another configuration example of a separable shaft member.
FIG. 8 is a conceptual diagram showing still another configuration example of the separable shaft member.
FIG. 9 is a conceptual diagram showing still another configuration example of the separable shaft member.
[Explanation of symbols]
1 Photosensitive drum 4 Developing device 41 Developing roller 43 Developing sleeve 44 Magnet roller body

Claims (10)

In the magnet roller having at least three magnetic poles extending along the longitudinal direction, it is separably formed in the shaft member for supporting the magnet portion and the magnet part having a magnet holding member for holding the at least three magnetic poles in the magnet roller are,
The shaft member penetrates the magnet holding member, the outer peripheral surface of the shaft member is provided with a protrusion shape that can be one-way in the insertion / drawing direction, and when removing the shaft member, The magnet roller, wherein the shaft member is removable by pushing or pulling out the shaft member in a one-way insertion direction .   2. The magnet roller according to claim 1, wherein the shaft member includes a notch or a protrusion in a range of insertion into the magnet portion, and a hole having a shape corresponding to the notch or protrusion is provided on the end surface of the magnet portion. The magnetic roller comprises a non-magnetic sleeve and a magnet roller fixedly disposed in the sleeve, and draws the developer on the sleeve surface to form a magnetic brush on the sleeve surface. A magnetic brush carrying roller with a pumping magnetic pole, a developer conveying magnetic pole, and a main magnetic pole for developing a developer,
In the magnetic brush carrier roller in which the magnet roller is formed so as to be separable by a magnet part having a magnet holding member that holds the developer pumping magnetic pole, developer transporting magnetic pole and main magnetic pole, and a shaft member that supports the magnet part .
The shaft member penetrates the magnet holding member, the outer peripheral surface of the shaft member is provided with a protrusion shape that can be one-way in the insertion / drawing direction, and when removing the shaft member, The magnetic brush carrying roller, wherein the shaft member is removable by pushing or pulling out the shaft member in a one-way insertion direction . 4. The magnetic brush carrying roller according to claim 3 , wherein the shaft member has a notch or a protrusion in an insertion range into the magnet portion, and a hole having a shape corresponding to the notch or protrusion is provided on the end surface of the magnet portion. A developing device incorporating the magnetic brush carrying roller according to claim 3 or 4 . 5. A cleaning device incorporating the magnetic brush carrying roller according to claim 3 or 4 . A charging device incorporating the magnetic brush carrying roller according to claim 3 or 4 . An apparatus for capturing a developer for preventing carrier scattering, comprising the magnetic brush carrying roller according to claim 3 . An image forming apparatus comprising at least one of the developing device according to claim 5 , the cleaning device according to claim 6 , the charging device according to claim 7 , and the developer capturing device for preventing carrier scattering according to claim 8 . A magnet roller formed so as to be separable between a magnet part having a magnet holding member for holding at least three magnetic poles extending along the longitudinal direction and a shaft member supporting the magnet part, wherein the shaft member is In the method of removing the shaft member from the magnet roller adapted to penetrate the magnet holding member,
Provided on the outer peripheral surface of the shaft member is a protrusion shape that can be inserted and pulled out in a one-way direction, and when removing the shaft member, the shaft member is pushed out or pulled out in the direction in which the one-way can be inserted. Removing
Removal method characterized by.

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