JP2006165477A - Magnet roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve releaseability of a developer by forming an odd-number of poles in a shaft-integrated magnet roller or a shaft-inserted magnet roller. <P>SOLUTION: In the magnet roller where a shaft and a magnet main body are molded integrally, the maximum value of a magnetic flux density of at least one of two adjacent magnetic poles having the same polarity of magnetic flux density is designated to be not smaller than 30 mT, and the minimum value of the magnetic flux density between the two poles is designated to be from 2 mT to 20 mT with the same polarity. Thus, the odd-number of poles can easily be formed, and an area between the two poles is designated to be a developer releasing area to improve the releaseability of the developer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnet roller incorporated in an image forming apparatus such as a copying machine, a printer, or a facsimile.

  In general, a magnet roller incorporated in an image forming apparatus using powder toner in a copying machine, a printer, a facsimile machine or the like is configured as follows.

That is, (1) Since the intervening pole piece is interposed between the magnetic pole pieces at a position where the same pole pieces are adjacent to each other, the magnetic field waveform between the same poles can be easily controlled. This improves the performance. (Patent Document 1) (2) By providing a notch portion in a magnetic field molding piece in an adjacent portion of the same-polarity magnetic waveform, image quality deterioration due to developer drifting is prevented. (Patent Document 2)
JP 2001-34068 A JP 2003-229309 A

However, since Patent Document 1 has a magnet piece corresponding to each magnetic pole and a magnet piece provided at a position corresponding to the developer peeling area, it takes time and effort to bond the magnet pieces. An error in pasting may occur, the developer peeling area may be shifted from a desired position, and the developer peeling may not be performed well.

  Also, in Patent Document 2, as in the above case, it takes time to bond the magnet pieces together, an error in bonding occurs, the developer peeling area is shifted from the desired position, and the developer peeling is performed well. There are cases where it is not.

  Furthermore, the current shaft-integrated magnet roller (the shaft and the magnet body are integrally formed of the same resin magnet material) usually has a four-pole configuration and does not require developer peeling. Used in development systems (using magnetic toner). In the case of this four-pole configuration, the angle between the poles of adjacent magnetic poles is about 50 degrees even if it is narrow, so that the yoke and the excitation source (permanent magnet or electromagnet) that orients and magnetizes each magnetic pole interfere with each other. In order to form a 5-pole configuration, it is necessary to increase one or two or more yokes and excitation sources. Therefore, adjacent yokes and excitation sources (permanent magnets or electromagnets) interfere with each other, A 5-pole configuration may not be formed.

  The magnet roller of the present invention is a magnet roller in which a shaft portion and a magnet main body portion are integrally formed, and has two maximum values and one minimum value in a developer peeling region formed with the same polarity. A magnet roller having a maximum density of 30 mT or more and a minimum magnetic flux density of 2 mT to 20 mT.

  The magnet roller of the present invention is the magnet roller according to claim 1, wherein the developer peeling region has a minimum value of 10 mT to 20 mT and a magnetic flux density value between the maximum values of 30 mT or less is 15 degrees. The magnet roller is characterized by the above.

    The present invention also relates to a magnet roller with a shaft according to claim 1, wherein the shaft is inserted into a mold in advance, and then a resin magnet material for forming a magnet main body is injected into the mold. It is.

  According to the present invention (invention 1), a magnetic flux density pattern having an odd-numbered pole configuration can be easily obtained with a shaft-integrated magnet roller, and a good developer peeling region can be obtained.

  According to the present invention (Claim 2), it is possible to obtain a developer peeling region having a better developer changeability with a shaft-integrated magnet roller.

  According to the present invention (Claim 3), a magnetic flux density pattern having an odd number of poles can be easily obtained with a magnet roller with a shaft, and a good developer peeling region can be obtained.

  The present invention is a magnet roller in which a shaft portion and a magnet body portion are integrally formed, and has two maximum values and one minimum value in a developer peeling region formed with the same polarity, and has a maximum magnetic flux density. A magnet roller having a value of 30 mT or more and a minimum magnetic flux density of 2 mT to 20 mT.

    Conventionally, as shown in Patent Documents 1 and 2 and the like, with a magnet piece bonding type magnet roller, it takes time to perform the bonding operation, which increases the cost, and the developer peeling region is desired due to a shift in bonding. In some cases, the developer is not peeled off well from the above position, and it is difficult to form the developer peeling area with the shaft-integrated magnet roller due to interference between the yoke and the excitation source.

  In the present invention, a mold (magnetic circuit portion) as shown in FIG. 1 is used, and a shaft portion and a main body portion are integrally injection-molded with a magnet material by a mixture mainly composed of ferromagnetic powder and a resin binder. Such a magnet roller is formed. The magnetic flux density pattern of the obtained magnet roller is as shown in FIG. As shown in FIG. 3, a demagnetizing yoke (electromagnet) or permanent magnet is brought into contact with the outer peripheral surface of the magnet roller corresponding to the vicinity of the magnetic flux density peak position of the N2 pole in FIG. The magnetic field at the time of demagnetization is adjusted according to the magnetic flux density peak value of the magnetic pole to be demagnetized. As shown in FIG. 4, the bottom value of the magnetic flux density after demagnetization is 2 mT to 20 mT, preferably 10 mT to 20 mT. Like that. In this case, when the bottom value is less than 2 mT, the developer is not peeled favorably, and the developer is swung around, which adversely affects the image quality. When it exceeds 20 mT, as in the case of less than 2 mT, the developer is not peeled off satisfactorily, causing the developer to rotate, which adversely affects the image quality.

  In the present invention, as shown in FIG. 6, the width of the orientation and magnetization yoke corresponding to the magnetic pole to be demagnetized needs to be 10% or more of the magnet outer peripheral dimension. Desirably, the content is 10% to 30%. When the yoke width is less than 10%, it is difficult to make the half-value width 80 degrees or more. When the yoke width exceeds 30%, the half-value width becomes 80 degrees or more, but the magnetic flux density peak value of the magnetic pole decreases and is practical. It may be an unintended value. As shown in FIG. 3, a demagnetizing yoke (electromagnet) or permanent magnet is brought into contact with the outer peripheral surface of the magnet roller corresponding to the vicinity of the magnetic flux density peak position of the magnetic pole (N2 pole) to be demagnetized in FIG. Do magnetism. The magnetic field at the time of demagnetization is adjusted according to the magnetic flux density peak value of the magnetic pole to be demagnetized, and as shown in FIG. 4, the bottom value of the magnetic flux density after demagnetization is 2 mT to 20 mT, preferably 10 mT to 20 mT. Like that. In this case, when the bottom value is less than 2 mT, the developer is not peeled favorably, and the developer is swung around, which adversely affects the image quality. When it exceeds 20 mT, as in the case of less than 2 mT, the developer is not peeled off satisfactorily, causing the developer to rotate, which adversely affects the image quality.

  Further, the present invention is the magnet roller according to claim 1, wherein the minimum value of the developer peeling region is 10 mT to 20 mT, and the range in which the magnetic flux density value between the maximum values is 30 mT or less is 15 degrees or more. It is a magnet roller characterized by.

  In the present invention, as shown in FIG. 6, the width of the orientation magnetized yoke corresponding to the magnetic pole to be demagnetized is set to 10% or more, preferably 10% to 30% of the outer circumference of the magnet, and the half width of the magnetic pole is As shown in FIG. 3, a demagnetizing yoke (electromagnet) or permanent magnet is provided on the outer peripheral surface of the magnet roller corresponding to the vicinity of the magnetic flux density peak position of the magnetic pole (N2 pole) to be demagnetized as shown in FIG. Demagnetize by abutting the magnet. The magnetic field at the time of demagnetization is adjusted according to the magnetic flux density peak value of the magnetic pole to be demagnetized, and as shown in FIG. 4, the bottom value of the magnetic flux density after demagnetization is set to 10 mT to 20 mT and within 30 mT or less. Is set to 15 degrees or more. In this case, the magnetic force in this range (30 mT or less) becomes almost zero or repulsive (force to peel off the developer from the sleeve), and the developer is peeled well. When the bottom value is less than 10 mT, the developer is not peeled off satisfactorily, causing the developer to rotate and adversely affecting the image quality. In the case of exceeding 20 mT, as in the case of less than 10 mT, the developer is not peeled off satisfactorily, causing the developer to rotate and adversely affecting the image quality. When the range of 30 mT or less is less than 15 degrees, the developer is once peeled off from the sleeve, but since the adjacent downstream magnetic force (attraction force) exists nearby, the developer once peeled off is removed. Then, it is adsorbed on the sleeve again, and as a result, the developer is not peeled off favorably, and the developer is swung around, which adversely affects the image quality.

  Here, the magnet roller is mainly composed of a mixture of 50% by weight to 95% by weight of anisotropic ferrite magnetic powder and 5% by weight to 50% by weight of resin binder, and if necessary, the surface of the magnetic powder. As a processing agent, coupling agents such as silane and titanate, polystyrene and fluorine lubricants that improve fluidity, stabilizers, plasticizers, flame retardants, etc. are added, mixed and dispersed, melt kneaded, After molding into a pellet, injection molding is performed.

  The orientation magnetization magnetic field applied at the time of molding may be appropriately selected according to the magnetic flux density specification required for each magnetic pole. Further, depending on the required magnetic properties, the orientation magnetization magnetic field may not be applied at the time of molding, and may be magnetized after molding.

  The magnet roller uses a mold as shown in FIG. 1 or FIG. 5, and 240 K · A / m to 2400 K by an orientation magnetizing yoke disposed in the mold with a molten resin magnet from the injection port and an electromagnet or permanent magnet. Injecting while applying a magnetic field of A / m, magnetic particles are oriented and magnetized in a desired direction and cured to obtain a magnet roller. Since the obtained magnet roller is molded in a mold by injection molding, the dimensional accuracy is better than that of an extruded product, so that post-processing is not required, and a high dimensional accuracy magnet roller can be obtained at low cost. . Also, in the case of injection molding, the melt viscosity of the molten resin magnet is much lower than that of extrusion molding, etc., so the degree of orientation of magnetic particles is improved, a magnet piece with high magnetic properties is obtained, and developer transportability is good In addition, developer fogging can be prevented and high image quality is achieved.

Here, examples of the magnetic powder include anisotropic ferrite magnetic powder having a chemical formula represented by MO.nFe ₂ O ₃ (n is a natural number). As M in the formula, one or more of Sr, Ba, lead and the like are appropriately selected and used.

  Further, as a resin binder, polyamide resin, ethylene-ethyl acrylate resin, polystyrene resin, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), EVA (ethylene-vinyl acetate copolymer), EVOH ( One or more of thermoplastic resins such as ethylene-vinyl alcohol copolymer), CPE (chlorinated polyethylene), and PVC (polyvinyl chloride), or epoxy resin, phenol resin, urea resin, melamine resin, One kind or two or more kinds of thermosetting resins such as furan resin, unsaturated polyester resin and polyimide resin can be used in combination.

  Further, depending on the required magnetic flux density, as magnetic powder, anisotropic ferrite magnetic powder, isotropic ferrite magnetic powder, anisotropic rare earth magnetic powder (for example, SmFeN system), isotropic rare earth magnetic powder (for example, NeFeB system) May be used alone or in admixture of two or more.

  If the content of the single magnetic powder or the mixed magnetic powder shown above is less than 50% by weight, the magnetic properties of the magnet piece are lowered due to insufficient magnetic powder, making it difficult to obtain a desired magnetic force. If it exceeds 95% by weight, the binder becomes insufficient and the moldability may be impaired.

  Moreover, this invention is a magnet roller with a shaft of Claim 1, 2 which inserts a shaft in a metal mold | die beforehand and forms a magnet main-body part after that.

    In the present invention, a shaft insert mold (magnetic circuit part) as shown in FIG. 5 is used, and a magnet body part is injection-molded with a magnet material on the outer peripheral part of the shaft by a mixture mainly composed of ferromagnetic powder and resin binder. Thus, a magnet roller as shown in FIG. 8 is formed. The magnetic flux density pattern of the obtained magnet roller is as shown in FIG. As shown in FIG. 3, a demagnetizing yoke (electromagnet) or permanent magnet is brought into contact with the outer peripheral surface of the magnet roller corresponding to the vicinity of the magnetic flux density peak position of the N2 pole in FIG. The magnetic field at the time of demagnetization is adjusted according to the magnetic flux density peak value of the magnetic pole to be demagnetized, and as shown in FIG. 4, the bottom value of the magnetic flux density after demagnetization is 2 mT to 20 mT, preferably 10 mT to 20 mT. Like that. In this case, when the bottom value is less than 2 mT, the developer is not peeled favorably, and the developer is swung around, which adversely affects the image quality. When it exceeds 20 mT, as in the case of less than 2 mT, the developer is not peeled off satisfactorily, causing the developer to rotate, which adversely affects the image quality. Further, in this specification, a magnet roll having a five-pole configuration is illustrated, but the present invention is not limited to a five-pole magnet roll. That is, the number of magnet pieces may be selected according to the desired magnetic flux density and magnetic field distribution, and the number of magnetic poles and the magnetic pole position may be set as appropriate.

  Furthermore, when a magnetic field is applied simultaneously with molding, in order to improve the demoldability of the molded product, to prevent adhesion of dust such as magcus of the molded product, and to facilitate the handling of the magnet roller, It may be demagnetized once outside the mold and then magnetized.

  Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1
As the magnetic roller material of FIG. 7, an anisotropic strontium ferrite magnetic powder (SrO · S) is used as a magnetic powder in 10% by weight of nylon 6 (A1015P manufactured by Unitika Co., Ltd.) as a resin binder. 6Fe ₂ O ₃ ) 90% by weight, these are mixed, melt-kneaded, formed into pellets, the pellets are melted, and the molten resin magnet material is introduced from the inlet using the mold shown in FIG. The magnetic particles of the molten resin magnet were oriented and magnetized while being injected and injected with a magnetic field of 500 K · A / m to 1500 K · A / m, and the magnet roller shown in FIG. 7 was injection molded. The outer diameter of the magnet roller main body was 13.6, the length of the magnet main body was 320 mm, and the outer diameter of the shaft was 6 mm. (The material of the main body and shaft is the same resin magnet material)
The probe (magnetic flux density sensor) is set at a position 8 mm away from the center of the magnet roller (on the sleeve) while supporting the shafts on both ends of the obtained magnet roller and rotating the magnet roller. The circumferential magnetic flux density pattern was measured. A magnetic flux density pattern of the magnet roller is shown in FIG.

A demagnetizing yoke (electromagnet) is brought into contact with the outer peripheral surface of the magnet roller corresponding to the vicinity of the magnetic flux density peak position of the N2 pole shown in FIG. 2, and the maximum value of the magnetic flux density is 30 mT or more (10 = 40 mT, 11 = 30 mT in FIG. 4). ) And the magnetic flux density has a minimum value (bottom value) of 2 mT, and a magnetic flux density pattern as shown in FIG. 4 is formed. The magnet roller after demagnetization is a developing roller with a sleeve (sleeve outer diameter is φ16), a flange, etc., and as shown in FIG. 9, a developer (two-component developer: magnetic carrier + non-magnetic) on the sleeve (Toner) 100 g is uniformly adsorbed in the longitudinal direction, and the sleeve is rotated at a speed of 200 rpm for 1 minute via a flange on the driving side, and during this time, the presence or absence of developer stagnation in the developer peeling area is visually observed. At the same time, the amount of developer remaining on the sleeve after the rotation was stopped was measured with a precision balance. The remaining amount of developer on the sleeve was determined to be 3 g or less.
The observation and measurement results are shown in Table 1.

(Example 2)
The same procedure as in Example 1 was performed except that the maximum value of the magnetic flux density was 30 mT or more (10 = 60 mT, 11 = 40 mT in FIG. 4) and the minimum value (bottom value) of the magnetic flux density was 20 mT. The observation and measurement results are shown in Table 1.

(Example 3)
Before the molten resin magnet material is injected and injected using the mold shown in FIG. 5, the shaft is inserted into the mold, and the molten resin magnet material is injected and injected into the outer peripheral portion of the shaft from the injection port. The magnetic particles of the molten resin magnet were oriented and magnetized while applying a magnetic field of A / m to 1500 K · A / m, and the magnet roller shown in FIG. 8 was injection molded. The same procedure as in Example 1 was performed except that the outer diameter of the magnet roller main body portion was φ13.6, the length of the magnet main body portion was 320 mm, the outer diameter of the shaft portion was φ6, and the material was SUM22.
The observation and measurement results are shown in Table 1.

Example 4
The same procedure as in Example 3 was performed except that the maximum value of the magnetic flux density was 30 mT or more (10 = 60 mT, 11 = 40 mT in FIG. 4) and the minimum value (bottom value) of the magnetic flux density was 20 mT. The observation and measurement results are shown in Table 1.

(Example 5)
The same procedure as in Example 1 was performed except that the half width of the N2 pole was set to 80 degrees by adjusting (increasing) the yoke width corresponding to the N2 pole based on the mold shown in FIG.
The observation and measurement results are shown in Table 1.

(Example 6)
The same procedure as in Example 1 was performed except that the half width of the N2 pole was set to 120 degrees by adjusting (increasing) the yoke width corresponding to the N2 pole based on the mold of FIG.
The observation and measurement results are shown in Table 1.

(Example 7)
The maximum value of the magnetic flux density is 30 mT or more (10 = 50 mT, 11 = 40 mT in FIG. 4), the minimum value (bottom value) of the demagnetized magnetic flux density pattern is 5 mT, and the range of 30 mT or less is 15 degrees. Except for demagnetizing the N2 pole, everything was performed in the same manner as in Example 3.
The observation and measurement results are shown in Table 1.

(Example 8)
N2 so that the maximum value of the magnetic flux density is 30 mT or more (10 = 50 mT, 11 = 50 mT in FIG. 4) and the minimum value (bottom value) of the demagnetized magnetic flux density pattern is 10 degrees and 30 mT or less is 10 degrees. Except for demagnetizing the poles, all operations were performed in the same manner as in Example 3.
The observation and measurement results are shown in Table 1.

Example 9
N2 so that the maximum value of the magnetic flux density is 30 mT or more (10 = 50 mT, 11 = 50 mT in FIG. 4), and the minimum value (bottom value) of the demagnetized magnetic flux density pattern is 10 mT and 30 mT or less is 15 degrees. Except for demagnetizing the poles, all operations were performed in the same manner as in Example 3.
The observation and measurement results are shown in Table 1.

(Example 10)
N2 so that the maximum value of the magnetic flux density is 30 mT or more (10 = 60 mT, 11 = 40 mT in FIG. 4) and the minimum value (bottom value) of the demagnetized magnetic flux density pattern is 20 mT and 30 mT or less is 15 degrees. Except for demagnetizing the poles, all operations were performed in the same manner as in Example 3.
The observation and measurement results are shown in Table 1.

(Example 11)
By adjusting (increasing) the yoke width corresponding to the N2 pole based on the mold in FIG. 1, the half width of the N2 pole is set to 120 degrees, and the maximum value of the magnetic flux density is 30 mT or more (10 = 55 mT in FIG. 4). 11 = 50 mT) and the same procedure as in Example 3 except that the N2 pole is demagnetized so that the minimum value (bottom value) of the demagnetized magnetic flux density pattern is 15 degrees and 30 mT or less is 15 degrees. It was.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the maximum value of the magnetic flux density was 30 mT or more (10 = 30 mT, 11 = 30 mT in FIG. 4) and the minimum value (bottom value) of the demagnetized magnetic flux density pattern was 1 mT. .
The observation and measurement results are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the maximum value of the magnetic flux density was 30 mT or more (10 = 60 mT, 11 = 40 mT in FIG. 4) and the minimum value (bottom value) of the demagnetized magnetic flux density pattern was 25 mT. .
The observation and measurement results are shown in Table 1.

実施例１、２、３、４と比較例１、２を比べると、実施例１、２、３、４は現像剤のつれ回りも無く、スリーブ上の現像剤残量も３ｇ以下となっており、現像剤剥離性も実用的には問題ないことがわかる。

Comparing Examples 1, 2, 3, and 4 with Comparative Examples 1 and 2, Examples 1, 2, 3, and 4 are free of the developer and the remaining amount of developer on the sleeve is 3 g or less. Thus, it can be seen that there is no practical problem with the developer peelability.

  Therefore, it can be seen that the minimum value (bottom value) of the magnetic flux density of the magnetic pole having the maximum magnetic flux density of 30 mT or more and demagnetized is preferably 2 mT to 20 mT.

When Examples 5 and 6 are compared with Examples 1, 2, 3, and 4, Examples 5 and 6 have a developer peeling region of 30 mT or less by increasing the half-value width of the N2 pole (the magnetic pole to be demagnetized). As a result, the remaining amount of the developer on the sleeve is reduced as compared with Examples 1, 2, 3, and 4, and it can be seen that there is no practical problem with the developer peelability.
Therefore, it can be seen that the half width of the magnetic pole to be demagnetized is desirably 80 degrees or more.

  When Examples 9, 10, and 11 are compared with Examples 7 and 8, Examples 9, 10, and 11 have no developer swirling and the remaining amount of developer on the sleeve is less than 1 g. It can be seen that the developer peelability is good.

Accordingly, the half width of the magnetic pole to be demagnetized is 80 degrees or more, the maximum value of the magnetic flux density is 30 mT or more, the minimum value (bottom value) of the magnetic flux density is in the range of 10 mT to 20 mT, and the developer peeling area is 30 mT or less. The width is desirably 15 degrees or more.

Mold for molding magnetic roller (magnetic circuit) Magnetic flux density pattern on the sleeve of the magnet roller Diagram explaining demagnetization of N2 pole The figure explaining the magnetic flux density pattern of the magnet roller of this invention Mold for shaft insert type magnet roller (magnetic circuit) The figure explaining the orientation magnetizing yoke vicinity of the N2 pole part of this invention Magnet roller of the present invention Another magnet roller of the present invention Device for observing developer peeling state of developing roller

Explanation of symbols

1 Magnet roller body 2 Yoke (magnetic material)
3 Electromagnet or permanent magnet 4 Magnetic flux density pattern 5 N1 pole magnetic flux density peak position 6 S1 pole magnetic flux density peak position 7 N2 pole magnetic flux density peak position 8 S2 pole magnetic flux density peak position 9 Sleeve 10 Magnetic flux density maximum value 11 Other magnetic flux density Maximum value 12 Magnetic flux density minimum value 13 Shaft 14 Shaft (molded with resin magnet material)
15 Shaft (SUM22)
16 Developer Adsorbed on Sleeve 17 Driving Flange 18 Developing Roller Support Jig 19 Developer Roller Support Jig Base

Claims (3)

  A magnet roller in which a shaft portion and a magnet body portion are integrally formed, and in a developer peeling region formed with the same polarity, the maximum value of magnetic flux density is 30 mT or more with two maximum values and one minimum value. A magnetic roller having a minimum magnetic flux density of 2 mT to 20 mT.   2. The magnet roller according to claim 1, wherein a range in which the minimum value of the developer peeling region is 10 mT to 20 mT and the magnetic flux density value between the maximum values is 30 mT or less is 15 degrees or more. roller.   The magnet roller with a shaft according to claim 1 or 2, wherein the shaft is inserted in the mold in advance, and then a resin magnet material for forming the magnet main body is injected into the mold.

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