JP2002287500A - Developing roller and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roller having high magnetic characteristic and the high accuracy of a main pole part, and to provide a method and a device for inexpensively and easily manufacturing the developing roller. SOLUTION: The thickness of an adhesive 51 for a high magnetic force magnet block attached to a housing groove 49 is made different in the shaft direction of the developing roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., a developing roller of a developing device mounted on the image forming apparatus, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Magnetic brush development using a two-component developer in electrophotography and other image forming methods using powder toner is well known and widely used in image forming apparatuses.

In this magnetic brush development, a magnetic brush is formed by magnetically adsorbing a developer on an outer peripheral surface of a developing roller, and a magnetic brush is formed in a developing area (an area where a developable electric field is secured between the developing roller and the image carrier). An electric field between the image carrier on which the electrostatic latent image is formed and the sleeve to which an electric bias is applied, selectively supplying and attaching toner from the magnetic brush to the latent image surface of the opposite image carrier. Thereby, development is performed.

The developing roller is usually formed as a cylindrical sleeve (developing sleeve), and has a magnet body (magnet roller) inside the sleeve which forms a magnetic field so as to cause the developer to spike on the surface of the sleeve. ing. When the ears are raised, the carrier is raised on the sleeve so as to follow the lines of magnetic force generated by the magnet roller, and the charged toner is attached to the carrier related to the raised ears. The magnet roller has a plurality of magnetic poles, and the magnets forming the respective magnetic poles are formed in a bar shape or the like. In particular, the developing roller is provided with a developing developing pole for starting up a developing agent in a developing region on the sleeve surface. By moving at least one of the sleeve and the magnet roller, the developer that has raised ears on the sleeve surface moves, and the developer conveyed to the developing area moves along a magnetic line of force generated from the developing electrode. The chains of the developer contact the surface of the image carrier so as to bend, and the chain of the contacted developer rubs against the electrostatic latent image based on the relative linear velocity difference with the image carrier. While
Supply toner.

In the conventional magnetic brush developing device, the developing condition for increasing the image density and the developing condition for obtaining a good contrast image are incompatible, and both the high density portion and the low density portion are simultaneously used. Difficult to improve. That is, the developing conditions for increasing the image density include (i)
For example, the developing gap, which is the distance between the image carrier and the developing sleeve, may be reduced, or (ii) the width of the developing area may be increased. On the other hand, developing conditions for obtaining a low-contrast image favorably include (i ′) widening the developing gap or (ii ′) narrowing the developing area width. In other words, both development conditions are opposite and incompatible, and it is generally difficult to satisfy both conditions over the entire density range to obtain a good quality image.

For example, when emphasis is placed on a low-contrast image, a so-called “back-end blank area” in which a blank portion occurs at a cross portion of a solid line, a black solid area, or a rear end section of a half-tone solid image.
An abnormal image called “image” easily occurs. Further, such a phenomenon that a horizontal line of a grid image formed with the same width becomes thinner than a vertical line, and a small point image such as one dot is not developed has occurred.

[0007] The development conditions for increasing the image density and the development conditions for obtaining a low-contrast image, which have been problems in the past, are satisfied at a high point in time, and a high-quality image can be obtained over the entire density range. The applicant of the present application has previously proposed a developing method and a developing device for obtaining the same (Japanese Patent Application 200
0-29637).

[0008]

However, in the developing device proposed by the applicant of the present invention, since the angle between the main poles of the developing roller is narrower than that of the conventional developing roller, it is difficult to use magnet material. High magnetic properties are required.
In addition, the accuracy of the main pole portion is required to be higher than that of the conventional developing roller (± 1 ° for the conventional ± 2 °).

[0009] In order to achieve these requirements, it has been difficult to implement the conventional materials, roller configuration and manufacturing method. In particular, with respect to magnet materials, generally used ferrite-based magnets cannot provide sufficient magnetic properties, so that it is necessary to use rare-earth magnets. In addition, since rare earth magnets are expensive, as a realistic roller magnet configuration,
It is desirable to use a rare earth magnet only for the main pole requiring high magnetic properties, and use a ferrite magnet for the other poles.

The developing roller 61 is, as shown in FIG.
Two types, a type in which the developing pole 68 is divided into three poles and a type in which the developing pole 68 shown in FIG. The type shown in FIG. 12 is a magnet roller having a six-pole type in which a development auxiliary pole is provided adjacent to the main development pole.
Is a magnet roller in which a rare earth magnet is arranged at a developing pole in a conventional four-pole type developing roller. In the type of FIG. 12, a development auxiliary electrode is provided on the adjacent pole of the main development pole,
It is a 6-pole type. Which magnetic waveform is used is determined by the specifications of the magnet roller.

The rare earth magnet arranged at the main developing pole has a width of 1.5 to 3 mm, a height of 2 to 3 mm, and a length of 300 to 310 m.
m. The rare earth magnet is arranged in the groove of the magnet roller and fixed with an adhesive to obtain a developing magnet roller. However, variations in magnetic properties (polar positions, magnetic flux densities) in the axial direction are problematic. The variation of the pole position is required to be ± 1 °, but is currently ± 1.5 ° or more. The magnetic flux density is required to be ± 5% or less, but may be ± 10% or more at present.

The cause of such a large variation is that, depending on the specifications of the magnet roller, the magnets are repelled by the repulsion between the magnets when the rare earth magnet is attached. It is conceivable that the ferrite magnet roller generates deflection, distortion, twist, and the like. In particular, variations in the magnetic flux density often occur because the distance from the rare earth magnet to the inner wall surface of the sleeve (hereinafter, referred to as MS gap) differs depending on the axial direction. Rare earth magnets have a large magnetic force, but as shown in the graph of FIG.
As the MS gap increases, the attenuation rate increases. That is, as the distance increases, the magnetic flux density greatly decreases. Isotropic Nd-Fe- with residual magnetic flux density (Br) of 600mT
When a B-based magnet is used, a reduction of about 8 mT occurs at 0.1 mm. The target specification value of the magnetic flux density on the sleeve surface is 90m
In the case of T, ± 5% is 4.5 mT, and the required bonding accuracy (height) of the rare earth mug is 0.056 mm.

As described above, a magnet roller using a rare earth magnet having a high magnetic force requires a high sticking accuracy. Furthermore, a magnet roller using a rare earth magnet with high magnetic force is obtained by arranging a rare earth magnet block in the groove of the developing pole part and fixing it with an adhesive,
The rare earth magnet block has a width of 1.5
15 mm, a height of 2 to 3 mm, and a length of 300 to 310 mm. When the rectangular parallelepiped is disposed in the developing pole portion, the axial peak magnetic flux density distribution of this portion is as shown in FIG. Density increases. The magnet 68 generally has a property (edge effect) in which the magnetic flux density at the end is high regardless of its shape and length. As a result, the magnetic flux density at both ends becomes high, and a uniform peak magnetic flux density distribution in the axial direction cannot be obtained. Cause. For this reason, it is necessary to keep the peak magnetic flux density constant in the axial direction in the image area.However, it is very difficult to eliminate the deviation of the peak magnetic flux density due to the nature of the magnet. This has been dealt with by making the magnet length longer than the effective development width. However, in this method, it is difficult to reduce the size of the developing device.

Further, a method of reducing the edge effect by providing ring-shaped magnets at both ends of a magnet roll has been known (Japanese Utility Model Publication No. 58-7388). However, in this structure, the number of parts is increased. There is a problem that the number of steps is expected to be increased, productivity is inferior, and cost is expected to be increased.

The present invention solves the above-mentioned conventional problems,
It is an object of the present invention to provide a developing roller having high-precision magnetic characteristics and a method for manufacturing the same.

In order to solve the above problems, the present invention provides a cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound. A developing roller in which a groove-shaped housing portion is provided at a portion corresponding to at least one developing pole, and a magnet block having a higher magnetic force than the magnet roll is fixed to the housing portion by an adhesive; It is characterized in that the thickness of the layer is different in the axial direction of the developing roller.

In the developing roller of the present invention, it is effective if the adhesive is a photo-curable adhesive. Further, in the developing roller of the present invention, it is effective if a notch is provided to irradiate the groove-shaped storage portion with light.

According to another aspect of the present invention, there is provided a cylindrical developing roller comprising a plastic magnet in which a magnetic powder is dispersed in a polymer compound. A developing roller in which a groove-shaped housing portion is provided in a portion corresponding to a pole, and a plastic magnet block having a higher magnetic force than the plastic magnet is fixed to the housing portion with an adhesive. Are characterized by different thicknesses in the axial direction.

In the developing roller of the present invention, it is effective if the groove-shaped storage portion has a different depth in the axial direction of the developing roller. Further, in order to solve the above problems, the present invention has a cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and at least one developing pole of the magnet roll In a developing roller in which a groove-shaped housing portion is provided in a corresponding portion, and a magnet block having a higher magnetic force than the magnet roll is fixed to the housing portion by an adhesive, the magnet block is positioned in the axial direction of the developing roller. It is characterized by different filling rates of magnet powder.

According to another aspect of the present invention, there is provided a cylindrical developing roller comprising a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound. In a method for manufacturing a developing roller, a groove-shaped housing portion is provided in a portion corresponding to a developing pole, and a magnet block having a higher magnetic force than the magnet roll is fixed to the housing portion by an adhesive. The adhesive is cured while maintaining a constant gap with the magnet block based on the smooth surface of the cored bar in the constituent member.

Further, in order to solve the above problems, the present invention provides a cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and at least one pole of the magnet roll. In a method of manufacturing a developing roller, a groove-shaped housing portion is provided at a portion corresponding to a developing pole, and a magnet block having a higher magnetic force than the magnet roll is fixed to the housing portion with an adhesive. Bonding
It is characterized in that when solidifying, it is adhered and solidified while applying different pressures in the axial direction of the developing roller.

[0021]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, an image forming unit of an image forming apparatus equipped with a developing device according to the present invention will be described with reference to FIG.

In FIG. 1, a charging device 2 for charging the surface of a photosensitive drum 1, which is an electrostatic latent image carrier, and a laser beam for forming a latent image on a uniformly charged surface. , A developing device 4 for forming a toner image by attaching charged toner to a latent image on the drum surface, a transfer device 5 for transferring the formed toner image on the drum to recording paper, A cleaning device 7 for removing the residual toner and a static elimination 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 is
The exposure 3 forms an electrostatic latent image, and the developing device 4 forms a toner image. The toner image is transferred from the surface of the photosensitive drum 1 to recording paper conveyed from a paper feed tray (not shown) by a transfer device 5 including a transfer belt or the like. The recording paper electrostatically attached to the photosensitive drum at the time of this transfer is separated from the photosensitive drum 1 by a separation claw. The unfixed toner image on the recording paper is fixed on the recording paper by the fixing device 9. 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 discharge lamp 8, and is used for the next image forming process. Reference numeral 6 denotes a registration roller for sending recording paper from a paper feed tray (not shown) in synchronization with the toner image on the photoconductor 1.

In the developing device 4, a developing roller 41, which is a developing roller, is disposed so as to be close to the photosensitive drum 1, and a developing area where the photosensitive drum and the magnetic brush contact each other is provided at both opposing portions. Are formed. Developing roller 41
Is such that a developing sleeve formed of a non-magnetic material such as aluminum, brass, stainless steel, or conductive resin in a cylindrical shape is rotated clockwise in the figure by a rotation driving mechanism (not shown). Reference numeral 42 denotes a doctor blade that regulates the height of the developer chain, that is, the amount of the developer on the developing sleeve, reference numeral 43 denotes an inlet seal member, and reference numeral 44 denotes a developer while stirring the developer in the developing device casing. This is a screw for pumping to the roller 41.

As shown in FIG. 2, the developing roller 41 has, as a core, a magnet body (hereinafter, referred to as a magnet roller 46) for forming a magnetic field in the developing sleeve 45 so as to cause the current agent to spike on the peripheral surface thereof. It is provided in gold 47 in a fixed state. The magnet roller 46 includes a developing pole 48 for causing the developer to spike in the developing area, a transport pole for transporting the pumped developer to the developing area, and a transport for transporting the developer in the developed area. With poles. In the present embodiment, the developing pole is formed by one magnet block 48. However, a plurality of magnet blocks 48 (two poles or three poles) are provided.
The developing pole may be formed by the (pole) magnet block. Then, the developing pole 48 is connected to one magnet block 4.
8, the half width of the developing pole is 25 ° or less, and the attenuation rate of the magnetic flux density in the normal direction of the developing magnetic pole is 40% or less. Note that the half width is an angular width of a portion indicating a half value of the highest normal magnetic force (apex) of the magnetic force distribution curve in the normal direction of the developing pole, and is, for example, the magnetic width of the magnet created by the N pole. 60 if the maximum normal magnetic force is 120mT
It is the angular width of the portion indicating the value of mT. The attenuation rate of the magnetic flux density in the normal direction of the developing magnetic pole is a numerical value indicating how much the magnetic flux density y in the normal direction at a portion 1 mm away from the surface of the developing roller is attenuated with respect to the magnetic flux density x in the normal direction ( x
-Y) Δx × 100%, for example, the magnetic flux density in the normal direction of the developing roller surface is 100 mT,
When the normal direction magnetic flux density at a portion separated by mm is 80 mT, the attenuation rate is 20%. The width indicated by the symbol MS in FIG. 2 is the MS gap.

The developing roller 41 is, for example, a magnet roller 4 having a deformed storage groove 49 as shown in FIG.
When the developing pole 6 is obtained by extrusion molding, the developing pole 48 which is a rare earth magnet block is mounted in the storage groove 49, and when the developing pole 48 is pressed from the developing pole side and fixed with an adhesive, the developing pole 48 also follows the deformation of the magnet roller 46. MS fixed
-The gap differs in the axial direction. For this reason, variations occur in the magnetic properties in the axial direction of the developing pole 48, particularly, the magnetic flux density, which adversely affects the development.

Therefore, when the magnet roller 46 is deformed due to blurring or distortion, as shown in FIG. 4, the thickness of the adhesive 51 layer is changed in the axial direction, and the accuracy of the application of the developing electrode 48 due to the deformation is changed. Variations are absorbed by the thickness of the adhesive 51.

According to this configuration, the magnet roller 4
Regardless of the performance of No. 6, the MS gap can always be kept constant by changing the thickness of the adhesive 51 layer in the axial direction.

In the present invention, the thickness of the adhesive is changed in the axial direction. To this end, the developing pole 48 is accommodated in a state where the magnet roller 46 is fixed to the upper stage of the sticking device with the rare earth magnet. It is necessary to cure the sheet after storing it in 49, adjusting the position and adjusting the height. Therefore, it is desired that the curing time of the adhesive 51 be short (1 min or less) from the viewpoint of productivity. Therefore, the adhesive 5
For example, a cyanoacrylate-based instantaneous adhesive, an anaerobic adhesive, and a photo-curable adhesive can be considered. The cyanoacrylate-based instantaneous adhesive and the anaerobic adhesive are instantaneous by blocking moisture and oxygen in the air. It has been found that it cannot be used because the curing progresses rapidly and the process time for positioning and height adjustment is restricted. Therefore, as the adhesive, ultraviolet light, visible light,
An acrylic, epoxy, thiol, silicone, or other photocurable adhesive that cures with an electron beam or the like is used.

The photocurable material that cures quickly does not cure unless light energy is applied, so that there is no restriction on the processing time for positioning, height adjustment, and the like. The best material. In addition, since the thickness of the adhesive 51 used in the present invention varies in the axial direction, it is necessary to increase the applied thickness of the adhesive in order to secure the thickness. Therefore, the viscosity of the adhesive 51 is preferably higher. A general photo-curable adhesive, for example, an ultraviolet-curable adhesive is generally 100 (cps) or less, but in the present invention, it is preferable to use 1,000 to 50,000 (cps).

By the way, even if the photocurable adhesive is applied to the accommodating groove 49 so that the MS gap is constant, and the developing electrode 48 is inserted thereafter, if the photocurable adhesive 51 is not irradiated with light, Uncured portions occur. Therefore, as shown in FIGS. 5 and 6, the adhesive 5
In FIG. 1, a notch 52 is provided in the rare-earth magnet housing groove 49 or in the vicinity thereof so that light indicated by an arrow L is irradiated by a lamp or the like.

By providing such a cut portion 52, light is easily irradiated to the photocurable adhesive 51,
The occurrence of the above-mentioned uncured portion can be prevented. FIG. 7 shows an attaching device used when the developing pole 48, which is a magnet block, is adhesively fixed to the housing groove 49 of the magnet roller 46. When attaching the magnet block 48 to the storage groove 49 of the magnet roller 46,
Using the smooth surface 47a formed on the metal core 47 of the magnet roller 46, the adhesive is cured by irradiating light while maintaining the gap G between the smooth surface 47a and the magnet block at a constant value. Thus, the smooth surface 47a
By hardening the adhesive 51 while keeping the gap G between the magnet block and the magnet block at a constant value, a developing roller having a constant MS gap can be easily obtained.

By the way, the developing roller 41 is
The magnet roll 46 provided with the rare earth magnet block is mounted in a non-magnetic cylindrical sleeve. The peak magnetic flux density on the surface of the sleeve 45 is proportional to the distance MS / gap between the magnet roller 46 and the inner wall surface of the sleeve. The rare-earth magnet has a larger magnetic force than a ferrite-based plastic magnet conventionally used for a magnet roller, but has a large attenuation rate as shown in FIG. That is, when the MS gap widens, the magnetic flux density is greatly attenuated. Conventionally, while a plastic magnet used for a magnet roller is reduced by about 4 mT at 0.1 mm, when an isotropic Nd-Fe-B-based magnet having a residual magnetic flux density (Br) of 600 mT is used, 0.1 m is reduced.
The reduction is about 8 mT in mm, and the attenuation factor is about twice.

With this property, the peak magnetic flux density distribution 52 on the sleeve surface of the developing pole 48 can be controlled by changing the thickness of the rare earth magnet block in the axial direction and changing the distance to the inner wall surface of the sleeve in the axial direction. Is possible. For example, in order to prevent the magnetic force at both ends from increasing due to the edge effect of the magnet, as shown in FIG.
The thickness of the end of the rare earth magnet block is made thinner than the center. At this time, by setting the MS gap G1 at the end to be larger than the MS gap G2 at the center,
The peak magnetic flux density distribution on the sleeve surface can be made uniform. In this case, as shown in FIG. 9, if the thickness is changed by providing the rare earth magnet block 48 with a step 48a, a step may also appear in the peak magnetic flux density distribution 52 in the axial direction, and as shown in FIG. If the thickness is changed with a smooth gradient 48b, the displacement of the peak magnetic flux density distribution 52 becomes smooth, and the axial magnetic flux density distribution 52 becomes more uniform.

As the magnet block, a plastic magnet or a rubber magnet in which a high molecular compound is mixed with magnetic powder is often used. The magnetic powder is Ne-based (Ne-Fe- or the like) or Sm-based (Sm
-Co, Sm-Fe-N, etc.)
PA-based materials such as PA or 12PA, ethylene-based compounds such as EEA (ethylene-ethyl copolymer) and EVA (ethylene-vinyl copolymer), chlorine-based materials such as CPE (chlorinated polyethylene), rubbers such as NBR As a thermoplastic resin such as a material and a thermosetting resin, there are an epoxy type, a silicone type, a urethane type and the like, and an epoxy type is mainly preferable. To form this magnet block,
There are different ways. The magnetic powder and the compound material of the polymer material are compression molded and thermally cured. The magnetic powder is compression molded, and the surface is coated for the purpose of rust prevention and fixing of the surface. The magnet block molded by the conventional method is adhered and fixed to the groove of the developing pole part, but when the solidification is performed by changing the filling rate of the magnetic powder in the axial direction using the method described above, the magnetic characteristics in the axial direction are reduced. It is possible to form different magnet blocks. For example, when the filling rate of the magnetic powder is made larger at the center than at both ends, an increase in the magnetic force at the ends due to the edge effect of the magnet can be suppressed, and the peak magnetic flux density distribution on the sleeve surface becomes uniform.

In order to make the peak magnetic flux density distribution on the sleeve surface uniform, as shown in FIG. 11, by changing the groove depth of the accommodating groove 49 to which the rare earth magnet block 48 is bonded in the axial direction, it is also possible to change the groove depth. The distance between the sleeve and the inner wall surface of the sleeve can be adjusted, and the peak magnetic flux density distribution on the sleeve surface can be controlled. To suppress the increase in magnetic force at the magnet end due to the edge effect, adjust the distance between the magnet block and the inner wall surface of the sleeve in the axial direction by making the groove at the end deep and shallow at the center to suppress the increase in magnetic force at the end. Can be. In this case, the shape of the rare earth magnet block does not need to be different in thickness in the axial direction.

When the pressure applied to the magnet block is changed in the axial direction when the rare earth magnet block is bonded and solidified to the groove accommodating portion of the mag roll, the filling rate of the magnetic powder in the axial direction can be changed. For example, in order to reduce the edge effect, if the applied pressure to the end portion is weakened and the applied pressure to the central portion is increased, the filling factor at the end portion is reduced and the increase in the magnetic force at the end portion can be suppressed.

[0038]

As described above, according to the present invention,
By changing the thickness of the adhesive in the axial direction, deformation such as warpage and distortion of the magnet roller can be absorbed, and the MS gap can be kept constant in the axial direction, so that variations in the magnetic flux density and magnetic pole angle of the developing pole can be reduced. Can be reduced.

Further, by using the photocurable adhesive as an adhesive, the adhesive can be bonded in a short time, so that the number of steps in the production process can be reduced, the productivity can be improved, and a low-cost developing roller can be achieved. is there.

Further, by providing a cut portion for irradiating the photo-curable adhesive with light in the vicinity of the rare-earth magnet housing portion, the photo-curable adhesive is efficiently cured and adhered in a short time. Therefore, man-hours in the production process can be reduced, productivity can be improved, and a low-cost developing roller can be achieved.

Further, by providing a manufacturing method capable of making the MS gap uniform in the axial direction, variations in the magnetic flux density of the developing pole and the magnetic pole angle can be reduced. Furthermore, since the magnet blocks having different shapes in the axial direction are arranged, the peak magnetic flux density on the sleeve surface can be adjusted by changing the distance between the magnet block and the inner wall surface of the sleeve. A stable SLIC developing roller can be provided.

Further, the peak magnetic flux density on the sleeve surface can be adjusted by changing the filling rate of the magnet powder in the magnet block in the axial direction, so that a developing roller having stable image characteristics can be provided.

Further, since the groove depth of the magnet roller is changed in the axial direction, the distance between the magnet block and the inner wall surface of the sleeve is changed, so that the peak magnetic flux density on the sleeve surface can be adjusted, and the image characteristics can be improved. , A stable developing roller can be provided.

Further, by changing the applied pressure in the axial direction when the magnet block is bonded and solidified, magnet blocks having different filling rates in the axial direction can be formed, thereby increasing the number of parts and man-hours and increasing the cost. And a developing roller having stable image characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing the vicinity of an image forming unit of an image forming apparatus equipped with a developing device according to the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a developing roller according to the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a developing roller having warpage.

FIGS. 4A and 4B are explanatory diagrams of a developing roller showing a portion where the thickness of an adhesive layer is changed.

FIG. 5 is an explanatory diagram of a developing roller showing a cut example of irradiating light;

FIG. 6 is an explanatory diagram of a developing roller showing another example of a cut for irradiating light.

FIG. 7 is an explanatory view showing a developing roller manufacturing apparatus according to the present invention.

FIG. 8 is an explanatory diagram showing another embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a modification of the embodiment in FIG. 8;

FIG. 10 is an explanatory diagram showing another modification of the embodiment of FIG. 8;

FIG. 11 is an explanatory view showing still another embodiment of the present invention.

FIG. 12 is an explanatory view showing a conventional developing roller.

FIG. 13 is an explanatory view showing a conventional developing roller.

FIG. 14 is a graph showing a relationship between an MS gap and a magnetic flux density.

FIG. 15 is an explanatory diagram showing a problem of a conventional developing roller.

[Explanation of symbols]

 41 developing roller 45 developing sleeve 46 magnet roller 48 developing electrode (magnet block) 49 storage groove 51 adhesive 52 magnetic flux density distribution

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mieko Kakegawa 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Noriyuki Kamiya 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Ricoh Company (72) Inventor Kyota Hitsuka 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Tomohiro Atsumi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company F-term (reference) 2H031 AB02 AC11 AC14 AC18 AC19 AC20 AC30 AC38 AD01 AD05

Claims (8)

[Claims] A cylindrical developing roller made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound and a magnet roller of a developing roller, and a groove-shaped housing is provided at a portion corresponding to at least one developing pole of the magnet roll. In the developing roller in which a portion is disposed and a magnet block having a higher magnetic force than the magnet roll is fixed to the housing portion by an adhesive, the thickness of the adhesive layer is different in the axial direction of the developing roller. A developing roller. 2. The developing roller according to claim 1, wherein
The developing roller, wherein the adhesive is a photocurable adhesive. 3. The developing roller according to claim 1, wherein
A developing roller provided with a cutout portion for irradiating light to the groove-shaped storage portion. 4. A cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and a groove-shaped housing is provided at a portion corresponding to at least one developing pole of the magnet roll. In a developing roller in which a portion is disposed and a magnet block having a higher magnetic force than the magnet roll is fixed to the storage portion by an adhesive, the thickness of the magnet block differs in the axial direction of the developing roller. Characteristic developing roller. 5. The developing roller according to claim 4, wherein
2. The developing roller according to claim 1, wherein the groove-shaped storage portion has a different depth in an axial direction of the developing roller. 6. A cylindrical developing roller made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and a magnet roller of a cylindrical developing roller, and a groove-shaped housing is provided at a portion corresponding to at least one developing pole of the magnet roll. In the developing roller, a portion is disposed, and a magnet block having a higher magnetic force than the magnet roll is fixed to the storage portion with an adhesive, wherein the magnet block has a different filling rate of magnet powder in the axial direction of the developing roller. A developing roller. 7. A cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and a groove-shaped housing is provided at a portion corresponding to at least one developing pole of the magnet roll. In the method for manufacturing a developing roller, a portion is disposed, and a magnet block having a higher magnetic force than the magnet roll is fixed to the storage portion with an adhesive, based on a smooth surface of a cored metal in a component member of the developing roller. A method of manufacturing the developing roller, wherein the adhesive is cured while maintaining a constant gap with the magnet block. 8. A cylindrical developing roller magnet roll made of a plastic magnet or the like in which a magnetic powder is dispersed in a polymer compound, and a groove-shaped housing is provided in a portion corresponding to at least one developing pole of the magnet roll. A part is disposed, and a magnet block having a higher magnetic force than the magnet roll is fixed to the storage part by an adhesive. When the magnet block is bonded and solidified, the shaft of the developing roller is fixed. A method for manufacturing a developing roller, wherein the developing roller is bonded and solidified while applying different pressures in different directions.