Magnet roller, method for manufacturing magnet roller, and developing device

Abstract

To provide a technique for improving accuracy in magnetic characteristics and shape.SOLUTION: A magnet roller 100 comprises a shaft 3, and a first magnet piece 1 and a second magnet piece 2. The first magnet piece 1 and the second magnet piece 2 are attached to an outer circumference of the shaft 3 with an adhesive 4. The first magnet piece 1 has a first surface 10 and a recess 15. The recess 15 is recessed relative to the first surface 10. The second magnet piece 2 has a second surface 20 and a projection 25. The second surface 20 contacts the first surface 10. The projection 25 protrudes relative to the second surface 20. The projection 25 fits into the recess 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a magnet roller, a method for manufacturing a magnet roller, and a developing device. [Background technology]

[0002] The magnet roller of Patent Document 1 includes a magnet and a shaft. The magnet is made up of five magnet pieces surrounding the shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-158154 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the magnet roller described in Patent Document 1, adjacent magnet pieces need to be attached to each other with adhesive at their flat contact surfaces.

[0005] On the other hand, when the contact surfaces are attached with adhesive, the adhesive may overflow from the edge of the contact surface onto the inner periphery of the magnet piece. In this case, the adhesive hardens between the magnet piece and the shaft on the inner periphery of the magnet piece. As a result, it is difficult to position the magnet piece and the shaft close to each other.

[0006] As described above, the magnet roller described in Patent Document 1 is difficult to properly position, and therefore the magnetic properties and shape precision cannot be improved.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique capable of improving the magnetic properties and shape accuracy. [Means for solving the problem]

[0008] According to a first aspect of the present invention, a magnet roller includes a shaft, a first magnet piece, and a second magnet piece. The first magnet piece and the second magnet piece are attached to the outer periphery of the shaft with an adhesive. The first magnet piece has a first surface and a recess. The recess is recessed relative to the first surface. The second magnet piece has a second surface and a protrusion. The second surface contacts the first surface. The protrusion protrudes relative to the second surface. The protrusion fits into the recess.

[0009] According to a second aspect of the present invention, a method for manufacturing a magnet roller is the same as the method for manufacturing a magnet roller according to the first aspect of the present invention. First and second magnet pieces are placed on a base. The second surfaces are brought into contact with the first surfaces so that the protrusions fit into the recesses. The first and second magnet pieces, with their protrusions fitted into the recesses, are lifted from the base. The first and second magnet pieces are attached to the outer periphery of the shaft with adhesive.

[0010] According to a third aspect of the present invention, a developing device including a magnetic roller is the developing device including the magnetic roller of the first aspect of the present invention. The developing device includes a developing magnetic roller. The developing magnetic roller is arranged to face an image carrier that carries an electrostatic latent image. The developing magnetic roller has a sleeve. The sleeve has the magnetic roller disposed therein. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a technique for improving the magnetic properties and the accuracy of the shape. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view of the magnet roller according to the embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the magnet roller taken along line II-II in FIG. [Figure 3]3 is an enlarged cross-sectional view of the lower half of the magnet roller corresponding to FIG. 2, with the second magnet piece omitted. [Figure 4] 3 is an enlarged cross-sectional view of the lower half of the magnet roller corresponding to FIG. 2, with the first magnet piece omitted. [Figure 5] 3 is an enlarged cross-sectional view of the lower half of the magnet roller corresponding to FIG. 2. FIG. [Figure 6A] FIG. 2 is a cross-sectional view showing a first magnet piece and a second magnet piece grounded to a base. [Figure 6B] 10 is a cross-sectional view showing a first magnet piece and a second magnet piece in which the first surface and the second surface are in contact with each other on a base. FIG. [Figure 6C] FIG. 2 is a cross-sectional view showing the first magnet piece and the second magnet piece lifted up from the base. [Figure 6D] 10 is a cross-sectional view showing the first magnet piece and the second magnet piece being attached to the outer periphery of the shaft from below. FIG. [Figure 7] 10 is a cross-sectional view showing how the first magnet piece and the second magnet piece are attached to the outer periphery of the shaft from above. FIG. [Figure 8] FIG. 2 is a perspective view of a developing device and an image carrier. [Figure 9] FIG. 1 is a schematic diagram of an image forming apparatus. [Figure 10] FIG. 2 is a schematic enlarged view of an image forming unit. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description will not be repeated. Furthermore, even if terms meaning specific positions and directions are used in the following description, these terms are used for convenience to facilitate understanding of the contents of the embodiments, and do not relate to the directions when actually implemented.

[0014] <Embodiment> A magnet roller 100 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view of the magnet roller 100 according to this embodiment. Figure 2 is a cross-sectional view of the magnet roller 100 of Figure 1 taken along line II-II.

[0015] 1, the magnet roller 100 includes a shaft 3, a first magnet piece 1, and a second magnet piece 2. The first magnet piece 1 and the second magnet piece 2 are attached to the outer periphery of the shaft 3 with an adhesive 4.

[0016] As shown in FIG. 2, the first magnet piece 1 has a first surface 10 and a recess 15. The recess 15 is recessed relative to the first surface 10. The second magnet piece 2 has a second surface 20 and a protrusion 25. The second surface 20 contacts the first surface 10. The protrusion 25 protrudes relative to the second surface 20. The protrusion 25 fits into the recess 15.

[0017] The above configuration can improve the magnetic properties and shape precision. Specifically, by fitting the convex portion 25 into the concave portion 15, adhesive is not required or only a small amount is required to join the first magnet piece 1 and the second magnet piece 2. As a result, no adhesive is required between the first magnet piece 1 and the second magnet piece 2 and the shaft 3, making it possible to position them close to each other. Furthermore, by fitting the convex portion 25 into the concave portion 15, misalignment between the first magnet piece 1 and the second magnet piece 2 is suppressed. As a result, the magnet roller 100 can improve the magnetic properties and shape precision by appropriately positioning the first magnet piece 1, the second magnet piece 2, and the shaft 3.

[0018] The magnet roller 100 will be described in detail below with reference to Figs. 3 to 5. Fig. 3 is an enlarged cross-sectional view of the lower half of the magnet roller 100 corresponding to Fig. 2, with the second magnet piece 2 omitted. Fig. 4 is an enlarged cross-sectional view of the lower half of the magnet roller 100 corresponding to Fig. 2, with the first magnet piece 1 omitted. Fig. 5 is an enlarged cross-sectional view of the lower half of the magnet roller 100 corresponding to Fig. 2.

[0019] 3 and 4, the recessed portion 15 and the protruding portion 25 have a width W in the radial direction of the shaft 3. The width W of the recessed portion 15 and the protruding portion 25 is 40% or less of the distance from one end 11, 21 to the other end 19, 29 of the first surface 10 and the second surface 20 in the radial direction, and is 0.5 mm or more. The distance from one end 11, 21 to the other end 19, 29 of the first surface 10 and the second surface 20 in the radial direction is sometimes referred to as the contact surface distance D.

[0020] By making the width W of the recessed portion 15 and the protruding portion 25 40% or less of the contact surface distance D, as shown in FIG. 3, the recessed portion outer side 18, which is from the other end 19 of the first surface 10 in the radial direction to the recessed portion 15, is shaped to a degree that makes it difficult for it to deform. Therefore, even if the protruding portion 25 fits into the recessed portion 15, the recessed portion outer side 18 is difficult to deform, so undesirable effects on the magnetic properties are suppressed. As a result, the magnet roller 100 can further improve the accuracy of the magnetic properties by suppressing undesirable effects on the magnetic properties.

[0021] By making the width W of the recessed portions 15 and the protruding portions 25 0.5 mm or more, misalignment between the first magnet piece 1 and the second magnet piece 2 is further suppressed. As a result, the magnet roller 100 can further improve the accuracy of its shape by further suppressing misalignment between the first magnet piece 1 and the second magnet piece 2.

[0022] The width W of the recessed portion 15 and the protruding portion 25 is preferably 1.0 mm or more. This is because when the width W of the recessed portion 15 and the protruding portion 25 is 1.0 mm or more, misalignment between the first magnet piece 1 and the second magnet piece 2 is further suppressed.

[0023] 5, the recessed portion 15 and the protruding portion 25 have a depth and length P in a direction perpendicular to the radial direction of the shaft 3. The first magnet piece 1 further has a third surface 13 in addition to the first surface 10 and the recessed portion 15.

[0024] Here, the midpoint that is equidistant from one end 11, 21 and the other end 19, 29 in the radial direction of the first surface 10 and the second surface 20 is sometimes referred to as the contact surface midpoint M. Furthermore, when an arc 16 centered on the axis 30 of the shaft 3 has the contact surface midpoint M and the third surface 13 as both ends, the length of the arc 16 is sometimes referred to as the predetermined arc length. The radius r of the arc 16 corresponds to the distance between the axis 30 of the shaft 3 and the contact surface midpoint M.

[0025] The depth and length P of the recessed portion 15 and the protruding portion 25 are 23% or less of the predetermined arc length and 1.0 mm or more.

[0026] By making the depth and length P of the recessed portion 15 and the protruding portion 25 23% or less of the predetermined arc length, the second magnet piece 2 that enters the inside of the first magnet piece 1 as the protruding portion 25 becomes shorter. As a result, the magnetism of the second magnet piece 2 does not significantly interfere with the magnetism of the first magnet piece 1, suppressing undesirable effects on the magnetic properties. As a result, the magnet roller 100 can further improve the precision of the magnetic properties.

[0027] By making the depth and length P of the recessed portions 15 and the protruding portions 25 1.0 mm or more, misalignment between the first magnet piece 1 and the second magnet piece 2 is further suppressed. As a result, the magnet roller 100 can have a further improved shape precision.

[0028] As shown in Figures 3 to 5, the recessed portions 15 and the protruding portions 25 are symmetrical on the side closer to and farther from the shaft 3 with respect to the contact surface midpoint M, which is the midpoint between one end 11 and 21 and the other end 19 and 29 in the radial direction of the first surface 10 and the second surface 20.

[0029] The recesses 15 and the protrusions 25 are symmetrical on the side closer to and farther from the shaft 3 with respect to the contact surface midpoint M, thereby suppressing undesirable effects on the magnetic properties. As a result, the magnet roller 100 can further improve the accuracy of the magnetic properties by suppressing undesirable effects on the magnetic properties.

[0030] Symmetry may mean partial symmetry or complete symmetry. As shown in Figures 3 to 5, it is preferable that the recessed portions 15 and the protruding portions 25 are completely symmetrical on the side closer to the shaft 3 and the side farther from the shaft 3 with respect to the contact surface midpoint M. Complete symmetry further suppresses undesirable effects on magnetic properties.

[0031] The materials of the first magnet piece 1 and the second magnet piece 2 will be described in detail below.

[0032] The first magnet piece 1 and the second magnet piece 2 are made of magnetic powder and resin. The magnetic powder contains ferrite. The ferrite is, for example, anisotropic ferrite. The magnetic powder containing ferrite improves the magnetic properties. Therefore, the magnet roller 100 can further improve the precision of the magnetic properties.

[0033] The magnetic powder further contains rare earth magnetic powder in addition to ferrite. The rare earth magnetic powder is, for example, neodymium, samarium cobalt, or samarium iron nitrogen. The magnetic powder is a mixture (blend) of ferrite and rare earth magnetic powder, which improves the magnetic properties. Therefore, the magnet roller 100 can further improve the precision of the magnetic properties. [Example]

[0034] Next, the magnet roller 100 according to the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

[0035] In all examples, the size and material of the magnet roller 100 were the same, with only the conditions (width W, depth, and length P) of the recessed portion 15 and the protruding portion 25 being different. Specifically, in the first magnet piece 1 and the second magnet piece 2 shown in FIG. 5, the distance between both ends (between top and bottom) of the recessed portion 15 and the protruding portion 25 in the width W direction was 5 mm, and the distance between both ends (between left and right) of the recessed portion 15 and the protruding portion 25 in the depth and length P direction was 8 mm. The first magnet piece 1 and the second magnet piece 2 were made of a resin primarily composed of polychloroethylene and anisotropic ferrite magnetic powder (85% by weight). The shaft 3 was φ6-330 mm and was nickel-plated 5 μm±2 μm on SUM23. The adhesive 4 was Aron Alpha (registered trademark) 800 series.

[0036] In all examples, an automatic magnetic field distribution measuring device 6800ROLL2 manufactured by Nippon Denji Sokki Co., Ltd. was used to measure the magnetic properties. Measurement positions were 10 positions spaced 10 mm apart from the axis 30 of the shaft 3 and evenly spaced along the axis 30 of the shaft 3. The rotation speed of the shaft 3 was approximately 6 seconds / revolution.

[0037] Of all the Examples (Example 1 to Example 15), Examples 1 to 7 are shown in Table 1 below, and Examples 8 to 15 are shown in Table 2 below. Table 1 is a table summarizing Examples 1 to 7, which gave more favorable results. Table 2 is a table summarizing Examples 8 to 15, which gave less favorable results than Table 1, but gave more favorable results.

[0038] In the following Tables 1 and 2, the "width W of the recess 15 and the protrusion 25 relative to the contact surface distance D" is simply referred to as the "relative width," the "depth and length P of the recess 15 and the protrusion 25 relative to a specified arc length" is simply referred to as the "relative depth, etc.", and the "misalignment between the first magnet piece 1 and the second magnet piece 2" is simply referred to as the "misalignment between the magnets."

[0039] [Table 1]

[0040] [Table 2]

[0041] *1 The preferred range for magnetic force is 55±6mT, and the even more preferred range is 55±5mT. *2 The preferred range for the polar angle is 0±8°, and the even more preferred range is 0±3°. *3 The half-value width is preferably in the range of 50±5°, and more preferably in the range of 50±3°.

[0042] As shown in Table 1, more favorable results were obtained in terms of magnetic properties and misalignment between magnets when the following conditions (1) and (2) were met. (1) Relative width is 40% or less and 10% (0.5 mm) or more (2) Relative depth, etc., is 23% or less and 12.5% ​​(1.0 mm) or more

[0043] As shown in Table 2, under the conditions (3) and (4) below, favorable results were obtained in terms of magnetic properties and misalignment between magnets, although not as good as those in Table 1. (3) Relative width is 60% or less and 8% (0.4 mm) or more (4) Relative depth, etc., is 40% or less and 10% (0.8 mm) or more

[0044] A manufacturing method of the magnet roller 100 will be described below with reference to Figs. 6A to 6D and 7. Fig. 6A is a cross-sectional view showing the first magnet piece 1 and the second magnet piece 2 grounded to a base B. Fig. 6B is a cross-sectional view showing the first magnet piece 1 and the second magnet piece 2 with the first surface 10 and the second surface 20 in contact with each other on the base B. Fig. 6C is a cross-sectional view showing the first magnet piece 1 and the second magnet piece 2 lifted from the base B. Fig. 6D is a cross-sectional view showing the first magnet piece 1 and the second magnet piece 2 being attached to the outer periphery of the shaft 3 from below. Fig. 7 is a cross-sectional view showing the first magnet piece 1 and the second magnet piece 2 being attached to the outer periphery of the shaft 3 from above.

[0045] As shown in FIG. 6A, a worker or a working device (neither of which is shown) places the first magnet piece 1 and the second magnet piece 2 on the base B.

[0046] As shown in FIG. 6B, an operator or a working device (neither of which is shown) brings second surface 20 into contact with first surface 10 so that protrusions 25 fit into recesses 15.

[0047] As shown in FIG. 6C, the worker or a working device (neither is shown) lifts up the first magnet piece 1 and the second magnet piece 2, with the protrusions 25 fitted into the recesses 15, from the base B.

[0048] As shown in FIG. 6D, a worker or a working device (neither is shown) attaches the first magnet piece 1 and the second magnet piece 2 to the shaft 3 from the outer periphery with adhesive 4.

[0049] The first magnet piece 1 and the second magnet piece 2 have the protrusions 25 fitted into the recesses 15, which prevents misalignment when lifting and attaching them to the shaft 3. Therefore, the manufacturing method for the magnet roller 100 can manufacture a magnet roller 100 with improved magnetic properties and shape precision.

[0050] As shown in Figure 6D, the first magnet piece 1 and the second magnet piece 2 may be attached to the shaft 3 from below, or as shown in Figure 7, the first magnet piece 1 and the second magnet piece 2 may be attached to the shaft 3 from above. Since the first magnet piece 1 and the second magnet piece 2 are attached to the shaft 3 from above, they need to be turned upside down from their lifted state.

[0051] The first magnet piece 1 and the second magnet piece 2 have the protrusions 25 fitted into the recesses 15, so misalignment is suppressed when the magnet roller 100 is turned upside down. Therefore, the manufacturing method for the magnet roller 100 can manufacture a magnet roller 100 with improved shape precision.

[0052] The developing device 200 including the magnet roller 100 will be described below with reference to Fig. 8. Fig. 8 is a perspective view of the developing device 200 and the image carrier 300.

[0053] The developing device 200 includes a developing magnetic roller 201. The developing magnetic roller 201 is disposed so as to face an image carrier 300. The image carrier 300 carries an electrostatic latent image.

[0054] The developing magnetic roller 201 has a magnet roller 100 and a sleeve 270. The sleeve 270 has the magnet roller 100 disposed therein.

[0055] The developing device 200 develops the electrostatic latent image on the image carrier 300 into a toner image with high precision. In particular, the developing device 200 is equipped with the magnet roller 100, which has improved magnetic properties and shape precision, and therefore is able to perform development with high precision.

[0056] The developing magnetic roller 201 further has two flanges 280. The two flanges 280 are adhered to the sleeve 270 so as to close the two openings of the sleeve 270. The sleeve 270 and the flanges 280 are both made of aluminum.

[0057] 9 and 10, an image forming apparatus 400 including a developing device 200 will be described. Fig. 9 is a schematic diagram of the image forming apparatus 400. Fig. 10 is a schematic enlarged view of an image forming section 430.

[0058] As shown in FIG. 9, the image forming apparatus 400 includes a sheet storage section 410, an upstream sheet transport path 420, an image forming section 430, and a downstream sheet transport path 440.

[0059] The sheet storage section 410 stores the sheet S. The upstream sheet transport path 420 transports the sheet S from the sheet storage section 410 to the image forming section 430. The image forming section 430 forms an image on the sheet S. The downstream sheet transport path 440 transports the sheet S from the image forming section 430. The upstream sheet transport path 420 and the downstream sheet transport path 440 are provided with a large number of transport rollers (not shown) for transporting the sheet S.

[0060] As shown in FIG. 10, the image forming section 430 includes the image carrier 300, a charging device 431, the developing device 200, a transfer roller 432, a transfer belt 433, and a cleaning member 434.

[0061] The image carrier 300 is a member having a photosensitive layer on its surface (periphery). The image carrier 300 is driven by, for example, a motor (not shown). The image carrier 300 is, for example, a photosensitive drum.

[0062] The charging device 431 uniformly charges the surface of the image carrier 300. An electrostatic latent image is formed on the uniformly charged surface of the image carrier 300 by an exposure device (not shown).

[0063] The developing device 200 develops the electrostatic latent image on the image carrier 300 into a toner image using a two-component developer containing toner and carrier.

[0064] Transfer roller 432 faces image carrier 300 across transfer belt 433. Transfer roller 432 transfers the toner image formed on the surface of image carrier 300 onto transfer belt 433.

[0065] The transfer belt 433 transfers the transferred toner image onto the sheet S. The transfer belt 433 is, for example, an endless belt.

[0066] The cleaning member 434 removes the toner remaining on the surface of the image carrier 300. The surface of the image carrier 300 from which the toner has been removed can once again be uniformly charged.

[0067] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit of the present invention. The drawings mainly show each component in a schematic manner to facilitate understanding, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the speed, material, shape, dimensions, etc. of each component shown in the above embodiments are merely examples and are not particularly limited, and various modifications are possible within a range that does not substantially deviate from the configuration of the present invention.

[0068] In the embodiment, the first magnet piece 1 and the second magnet piece 2 are described as being made of resin and magnetic powder, but they may also be made of rubber.

[0069] Although the shaft 3 in the embodiment is illustrated as being cylindrical, it may have other shapes such as a prism shape.

[0070] Although the first magnet piece 1 and the second magnet piece 2 in the embodiment are illustrated as having sector-shaped cross sections, they may have other shapes. [Industrial Applicability]

[0071] The present invention provides a magnet roller, a method for manufacturing a magnet roller, and a developing device, and has industrial applicability. [Explanation of symbols]

[0072] B. Pedestal P Depth and length W width 1. First magnet piece 2 Second magnet piece 3 shafts 4. Adhesive 10 Page 1 13 Page 3 15 recess 20 Side 2 25 Convex part 30 axis 100 Magnetic Roller 200 Developing device 201 Developing Mag Roller 300 Image carrier

Claims

1. A shaft, a first magnet piece and a second magnet piece attached to the outer periphery of the shaft with an adhesive; Equipped with The first magnet piece is The first page and a recess recessed relative to the first surface; and The second magnet piece is a second surface in contact with the first surface; a protrusion that protrudes from the second surface and fits into the recess; A magnetic roller having

2. the recess and the protrusion have a width in a radial direction of the shaft, 2. The magnet roller according to claim 1, wherein the width is 40% or less of the distance from one end to the other end of the first surface and the second surface in the radial direction, and is 0.5 mm or more.

3. the recess and the protrusion have a depth and a length in a direction perpendicular to a radial direction of the shaft, the first magnet piece further has a third surface in addition to the first surface and the recess, When an arc having a center on the axis of the shaft has a midpoint between one end and the other end of the first surface in the radial direction and the third surface as both ends, the length of the arc is defined as a predetermined arc length, The magnetic roller according to claim 1 , wherein the depth and the length are 23% or less of the predetermined arc length and 1.0 mm or more.

4. The magnetic roller according to claim 2 or 3, wherein the recesses and the protrusions are symmetrical on the side closer to and the side farther from the shaft with respect to a midpoint between one end and the other end of the first surface and the second surface in the radial direction.

5. the first magnet piece and the second magnet piece are made of magnetic powder and resin, The magnet roller according to claim 4 , wherein the magnetic powder comprises ferrite.

6. The magnet roller according to claim 5 , wherein the magnetic powder further comprises rare earth magnetic powder.

7. 3. A method for manufacturing the magnet roller according to claim 1 or 2, The first magnet piece and the second magnet piece are placed on a base; bringing the second surface into contact with the first surface so that the protrusion fits into the recess; Lifting the first magnet piece and the second magnet piece, with the protrusions fitted into the recesses, from the base; The manufacturing method of the magnet roller includes attaching the first magnet piece and the second magnet piece to the outer periphery of the shaft with the adhesive.

8. A developing device comprising the magnet roller according to claim 1 or 2, a developing magnetic roller disposed opposite to an image carrier carrying an electrostatic latent image; The developing device, wherein the developing magnet roller has a sleeve in which the magnet roller is disposed.

Images