Roller and image forming device

Abstract

In the roller and the image forming apparatus, compared with a case where a fixing portion is not provided on the portion of the shaft where the annular member is mounted, and a fixed portion fixed to the fixing portion is not provided on the annular member, the phenomenon of discharge occurring through a gap generated between the annular member and the elastic layer due to factors such as time is suppressed. The roller (6) includes: a conductive shaft (61); an elastic layer (62) provided on the shaft (61); and a non-conductive annular member (64) installed on at least one of the two end portions (61a, 61b) of the shaft (61) protruding from the two end portions (62e) of the elastic layer in the axial direction (D) in a state of contact with the end surface (62e) of the elastic layer, and a fixing portion (71) for fixing the installation position of the annular member (64) is provided at the parts of the two end portions (61a, 61b) of the shaft (61) where the annular member (64) is installed, and a fixed portion (73) fixed by the fixing portion (71) of the shaft (61) is provided on the inner peripheral surface of the annular member (64).

Description

Technical Field

[0001] The present invention relates to a roll and an image forming device. Background Art

[0002] Conventionally, there is a technique described in Patent Document 1 below regarding a roller or the like that is unlikely to cause leakage even when a high voltage is applied thereto.

[0003] Patent document 1 describes a roller component and an image forming device using the roller component as a transfer roller or a transfer opposing roller, wherein the roller component is a roller component having an elastic layer formed on the outer peripheral surface of a core rod, the core rod having a protrusion formed in a manner protruding from a range where the elastic layer is formed toward an axial end portion, and having a non-conductive component, wherein the non-conductive component is formed of a non-conductive material and is arranged on the protrusion in a manner so as to bite into the end face of the axial end portion of the elastic layer.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-9985 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] The present invention provides a roller and an image forming device using the roller, wherein the roller is provided with at least an elastic layer on a conductive shaft to which a voltage that may cause discharge may be supplied, and has a non-conductive annular component, wherein the non-conductive annular component is installed in the shaft at an end portion protruding from the end portion of the elastic layer in the axial direction in a state of contact with the end face of the elastic layer. In this roller, compared with a case where a fixing portion is not provided on the portion of the shaft where the annular component is installed, and a fixed portion fixed to the fixing portion is not provided on the annular component, the phenomenon of discharge occurring through a gap generated between the annular component and the elastic layer due to factors such as time can be suppressed.

[0009] [Technical means to solve the problem]

[0010] The roller of the present invention (A1) is as described in technical solution 1, comprising:

[0011] Conductive shaft;

[0012] an elastic layer disposed on the shaft; and

[0013] A non-conductive annular member is mounted on at least one of the two end portions of the shaft protruding from both end surfaces of the elastic layer in the axial direction in a state of contact with the end surface of the elastic layer.

[0014] The portions of the shaft at both ends where the annular member is mounted are provided with fixing portions for fixing the mounting position of the annular member in the axial direction.

[0015] A fixed portion fixed to the fixing portion of the shaft is provided on a portion of the inner peripheral surface of the annular member in the axial direction.

[0016] The roller of the present invention (A2) is the roller according to the invention A1, wherein a portion of the inner peripheral surface of the annular member other than a portion forming the fixed portion is configured as a press-fit portion that is press-fitted into the end portion of the shaft.

[0017] The roller of the present invention (A3) is a roller according to the invention A1, wherein the portion at the two ends of the shaft on which the annular component is installed is a two-stage stepped portion including a small diameter portion and a large diameter portion, and the annular component is a component with a two-stage shape having a small diameter portion and a large diameter portion, and the small diameter portion and the large diameter portion are respectively installed on the small diameter portion and the large diameter portion of the stepped portion of the shaft, the fixing portion is provided on the small diameter portion of the stepped portion of the shaft, and the fixed portion is provided on the inner circumferential surface of the small diameter portion of the annular component.

[0018] The roller of the present invention (A4) is a roller according to the invention A1, wherein the portion at the two ends of the shaft on which the annular component is installed is a two-stage stepped portion including a small diameter portion and a large diameter portion, and the annular component is a component with a two-stage shape having a small diameter portion and a large diameter portion, and the small diameter portion and the large diameter portion are respectively installed on the small diameter portion and the large diameter portion of the stepped portion of the shaft, the fixing portion is provided on the large diameter portion of the stepped portion of the shaft, and the fixed portion is provided on the inner circumferential surface of the large diameter portion of the annular component.

[0019] The roller of the present invention (A5) is the roller according to the invention A3, wherein the large diameter portion of the annular member is configured as a press-fit portion that is press-fitted into the large diameter portion of the shaft.

[0020] The roller of the present invention (A6) is the roller according to the invention A4, wherein the small diameter portion of the annular member is configured as a press-fit portion that is press-fitted into the small diameter portion of the shaft.

[0021] The roller of the present invention (A7) is the roller according to any one of the inventions A1 to A6, wherein the fixing portion is configured as a recessed portion, and the fixed portion is configured as a projecting portion fitted into the recessed portion.

[0022] The roller of the present invention (A8) is the roller according to any one of the inventions A1 to A6, wherein a protrusion that is inserted into the end surface of the elastic layer is provided on the end surface of the annular member that contacts the elastic layer.

[0023] Furthermore, the image forming device of the present invention (B) comprises: a roller having a conductive shaft, an elastic layer provided on the shaft, and a non-conductive annular member, wherein the non-conductive annular member is mounted on at least one of the two end portions of the shaft protruding from the two end surfaces of the elastic layer in the axial direction; and a power supply member for supplying a voltage to the shaft of the roller,

[0024] The roller includes the roller of any one of the inventions A1 to A8.

[0025] [Effects of the Invention]

[0026] According to the roller of the invention A1, compared with a case where a fixing portion is not provided on the portion of the shaft where the annular member is mounted, and a fixed portion fixed to the fixing portion is not provided on the annular member, it is possible to suppress the phenomenon of discharge occurring through the gap generated between the annular member and the elastic layer due to factors such as the passage of time.

[0027] According to the roller of the invention A2, compared with the case where the portion other than the portion forming the fixed portion on the inner peripheral surface of the annular member is not constituted as a pressed portion, the phenomenon of discharge occurring through the gap generated between the annular member and the elastic layer due to factors such as time can be more effectively suppressed.

[0028] According to the roller of the invention A3, the two-stage annular member can be attached in close contact with the elastic layer, and thus the occurrence of the discharge can be more reliably suppressed.

[0029] According to the roller of the invention A4, the two-stage annular member can be attached in close contact with the elastic layer, and thus the occurrence of the discharge can be more reliably suppressed.

[0030] According to the roller of the invention A5, the two-stage annular member can be attached to the elastic layer in a more stable manner in close contact with the elastic layer, and the occurrence of the discharge can be suppressed more reliably.

[0031] According to the roller of the invention A6, the two-stage annular member can be attached to the elastic layer in a more stable manner in close contact with the elastic layer, and the occurrence of the discharge can be suppressed more reliably.

[0032] According to the roller of the invention A7, the fixing portion and the fixed portion can be provided more easily than in the case where the fixing portion is not a recessed portion and the fixed portion is not a projecting portion.

[0033] According to the roller of the invention A8, the occurrence of the discharge can be more reliably suppressed compared to a case where the annular member is not provided with a protrusion that is inserted into the end surface of the elastic layer.

[0034] According to the image forming device of the invention B, compared with a case where a fixing portion is provided on a portion of the shaft where the annular component is mounted and a fixed portion fixed to the fixing portion is provided on the annular component which is not in the roller, the phenomenon of discharge occurring through the gap between the annular component of the roller and the elastic layer due to factors such as time can be suppressed, and the occurrence of secondary failures caused by the discharge can also be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram showing the structure of the image forming apparatus according to Embodiment 1.

[0036] Figure 2 Yes means Figure 1 A schematic diagram of a portion of an image forming apparatus (mainly an imaging apparatus) of FIG.

[0037] Figure 3 Yes means Figure 1 A schematic diagram of another part (mainly a secondary transfer part) of the image forming apparatus.

[0038] FIG. 4(A) is a schematic diagram showing the entire secondary transfer roller to which the roller of Embodiment 1 is applied, and FIG. 4(B) is a schematic diagram showing one end portion of the roller of FIG. 4(A) in an enlarged manner.

[0039] 5(A) is a schematic diagram showing a state where a holder and the like of one end portion of the secondary transfer roller of FIGS. 4(A) and 4(B) are removed, and FIG. 5(B) is a perspective view showing one end portion of the roller of FIG. 5(A) .

[0040] 6(A) is a perspective view showing one end portion of a shaft in the secondary transfer roller of FIGS. 5(A) and 5(B) , and FIG. 6(B) is a perspective view showing an annular member in the secondary transfer roller of FIGS. 5(A) and 5(B) .

[0041] FIG. 7(A) and FIG. 7(B) are schematic diagrams showing states of the annular member of FIG. 6(B) when viewed from different directions.

[0042] 8(A) is a schematic diagram showing one end portion of a shaft in the secondary transfer roller of FIGS. 5(A) and 5(B) , and FIG. 8(B) is a schematic cross-sectional view of the annular member of FIG. 7(B) taken along line QQ.

[0043] Figure 9(A) is a partial cross-sectional view showing the state of an annular member installed in one end of the secondary transfer roller of Figures 5(A) and 5(B), and Figure 9(B) is a longitudinal cross-sectional view of one end of the secondary transfer roller of Figures 5(A) and 5(B).

[0044] 10(A) and 10(B) are cross-sectional views showing the structure of one end portion of the secondary transfer roller according to the second embodiment.

[0045] FIGS. 11(A) and 11(B) are schematic diagrams showing the state when the annular member in the secondary transfer roller of FIGS. 10(A) and 10(B) is viewed from different directions.

[0046] 12(A) and 12(B) are diagrams showing a secondary transfer roller according to Embodiment 3, wherein FIG. 12(A) is a schematic diagram showing one end portion of a shaft in the secondary transfer roller, and FIG. 12(B) is a schematic cross-sectional diagram showing an annular member in the secondary transfer roller.

[0047] Fig.13 These are cross-sectional views showing the structure of one end portion of the secondary transfer roller according to the fourth embodiment.

[0048] FIG. 14(A) shows Fig.13 FIG. 14(B) is a schematic diagram showing one end portion of the shaft of the secondary transfer roller. Fig.13 A schematic cross-sectional view of an annular member in a secondary transfer roller.

[0049] 15(A) and 15(B) are schematic cross-sectional views showing the structure of an annular member in a secondary transfer roller of Comparative Example 1 and a state when discharge occurs.

[0050] 16(A) and 16(B) are schematic cross-sectional views showing the structure of an annular member in a secondary transfer roller of Comparative Example 2 and a state when discharge occurs.

[0051] [Explanation of Symbols]

[0052] 1: Image forming device

[0053] 6: Roller

[0054] 15: Power supply device (an example of a power supply component)

[0055] 61: Axis (an example of an axis)

[0056] 61a, 61b: Both ends

[0057] 62: Elastic layer

[0058] 62e: End face

[0059] 64: Ring-shaped member (an example of a ring-shaped component)

[0060] 71: Groove (an example of a fixing portion and a recessed portion)

[0061] 73: protrusion (an example of a fixed portion and a convex portion)

[0062] 75: Pressed part

[0063] 80: protrusion (an example of an inserted protrusion)

[0064] 351: Secondary transfer roller

[0065] 612: Large diameter part of the shaft

[0066] 613: Small diameter part of the shaft

[0067] 641: Small diameter portion of annular member

[0068] 642: Large diameter portion of annular member

[0069] D: Axis direction DETAILED DESCRIPTION

[0070] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0071] [Implementation Method 1]

[0072] Figure 1 In the figure, an image forming apparatus 1 according to the first embodiment is shown. Figure 1 In the other drawings of the invention, arrows with the symbols X, Y, and Z indicate the directions of width, height, and depth assumed in the drawings. Figure 1 , Figure 2 In the figures, the circular symbol at the intersection of the arrows of the symbols X and Y indicates that the direction of the symbol Z is directed vertically downward in the drawing.

[0073] <Image forming device>

[0074] The image forming apparatus 1 is an apparatus that forms an image containing toner as a developer on a sheet 9 as an example of a recording medium by using an image forming method such as an electrophotographic method. The image forming apparatus 1 is configured as, for example, a printer as described below, and the printer forms an image corresponding to image information input from an external device such as an information terminal or an image reading device.

[0075] The image forming device 1 is as follows Figure 1 As shown, the internal space of a frame 10 as an example of the main body of the device is provided with the following parts, namely: an image forming component 2, which forms a toner image as an unfixed image; an intermediate transfer component 3, which temporarily holds and conveys the toner image formed by the image forming component 2, and then transfers the toner image to a paper 9 for the second time; a paper supply component 4, which receives and delivers the paper 9 to be supplied to the secondary transfer position of the intermediate transfer component 3; and a fixing component 5, which fixes the toner image secondarily transferred by the intermediate transfer component 3 to the paper 9.

[0076] The frame 10 is a structure formed by assembling various supporting members, exterior materials, etc. into a desired structure and shape. The frame 10 has a discharge receiving section 12 formed on a portion of its upper surface, and the discharge receiving section 12 receives the discharged paper 9 with images formed thereon in a stacked state. Figure 1 The dotted chain line in shows a main conveyance path when the paper 9 is conveyed in the housing 10 .

[0077] The image forming unit 2 includes, for example, four imaging devices 2Y, 2M, 2C, and 2K. The four imaging devices 2Y, 2M, 2C, and 2K are dedicated to forming toner images of four colors, namely, yellow (Y), magenta (M), cyan (C), and black (K). The four imaging devices 2 (Y, M, C, and K) in the first embodiment are arranged in a Figure 1 The interior of the housing 10 shown is arranged in a state of being tilted toward the upper right.

[0078] Four imaging devices 2 (Y, M, C, K) are as follows Figure 1 or Figure 2 As shown in FIG. 1 , each of the photosensitive drums 21 includes a photosensitive drum 21 as an example of an image holding member, and the photosensitive drum 21 rotates in the direction indicated by an arrow.

[0079] Moreover, the imaging devices 2 (Y, M, C, K) are all equipped with the following machines around the photosensitive drum 21, namely: a charging device 22 for charging the image holding area of ​​the photosensitive drum 21; an exposure device 23 as an example of an exposure component, which exposes the charged image holding area of ​​the photosensitive drum 21 corresponding to the image information to form an electrostatic latent image; a developing device 24 (Y, M, C, K) for developing the electrostatic latent image formed on the image forming surface of the photosensitive drum 21 with toner of the corresponding color to form a toner image; and a first cleaning device 26 for cleaning the image forming surface of the photosensitive drum 21.

[0080] Figure 1 For convenience, all symbols 21 to 24 and 26 are recorded for the black (K) imaging device 2K, while only a part of the imaging devices 2Y, 2M and 2C of other colors are recorded and the remaining part is omitted.

[0081] The charging device 22 is a charging device of a contact charging method, that is, a charging roller 221 is used as an example of a contact charging member, and a required charging voltage is supplied to the charging roller 221 from the power supply device 15 to perform charging. Figure 2 Reference numeral 223 in the figure denotes a cleaning roller which contacts the charging roller 221 to clean the roller surface.

[0082] The developing devices 24 (Y, M, C, K) have substantially the same structure except that the color of the toner in the developer contained in the main body (housing) 241 thereof is one of the four colors (Y, M, C, K). Figure 2 As shown, a developing roller 242, a stirring member 243 such as an auger, and a layer thickness limiting member 244 are arranged in a main body 241. The developing roller 242 holds and rotates to transport the developer so that it passes through the developing process area facing the photosensitive drum 21. The stirring member 243 stirs and rotates to transport the developer in the main body 241 to supply it to the developing roller 242. The layer thickness limiting member 244 limits the amount (thickness) of the developer held by the developing roller 242. The developing roller 242 is supplied with a required development voltage from the power supply device 15 to perform development.

[0083] The intermediate transfer member 3 is disposed above the image forming devices 2 (Y, M, C, K) serving as the image forming member 2 in the housing 10 .

[0084] The intermediate transfer component 3 is composed of an intermediate transfer belt 31, a primary transfer device 33, a secondary transfer device 35 and a second cleaning device 36. The intermediate transfer belt 31 receives and holds the toner images formed by the imaging devices 2 (Y, M, C, K) respectively through the primary transfer, and then rotates to transport it to the position for secondary transfer to the paper 9. The primary transfer device 33 transfers the toner images formed on the photosensitive drums 21 of the imaging devices 2 (Y, M, C, K) to the image holding area on the outer peripheral surface of the intermediate transfer belt 31. The secondary transfer device 35 transfers the toner images on the intermediate transfer belt 31 to the paper 9 for the second time. The second cleaning device 36 cleans the outer peripheral surface of the intermediate transfer belt 31.

[0085] The intermediate transfer belt 31 is mounted on a plurality of support rollers 32a to 32d, and rotates in the direction indicated by the arrow while sequentially passing through the photosensitive drums 21 of the image forming devices 2 (Y, M, C, K) and the secondary transfer device 35. The support roller 32a is configured as a driving roller, and the support roller 32b is configured as a secondary transfer opposing roller.

[0086] Furthermore, the primary transfer device 33 is as follows Figure 1 or Figure 2 As shown, a transfer device of a contact transfer method is applied, which uses a primary transfer roller 331 as an example of a contact transfer member, and a necessary primary transfer voltage is supplied to the primary transfer roller 331 from the power supply device 15 to perform primary transfer.

[0087] Furthermore, the secondary transfer device 35 is as follows Figure 1 or Figure 3 As shown, a transfer device of a contact transfer method is applied, and the transfer device of the contact transfer method uses a secondary transfer roller 351 as an example of a contact transfer member, and a required secondary transfer voltage is supplied to the secondary transfer roller 351 from the power supply device 15 to perform secondary transfer.

[0088] The paper feed unit 4 is composed of a paper container 41 for storing paper 9, a feeding device 43 for feeding paper 9 one by one from the paper container 41, and the like. The paper 9 fed from the paper feed unit 4 is conveyed to a secondary transfer position between the intermediate transfer belt 31 and the secondary transfer device 35 in the intermediate transfer unit 3 via a paper feed conveying path including a paper conveying roller 45 and a conveying guide (not shown).

[0089] The fixing member 5 is arranged above the secondary transfer position of the intermediate transfer member 3. The fixing member 5 is configured by arranging a heating rotating body 51, a pressing rotating body 52 and other devices in the internal space of a frame 50. The paper 9 fed out of the fixing member 5 after fixing is conveyed to the discharge storage section 12 via a discharge path including a paper conveying roller 47, a conveying guide (not shown) and the like.

[0090] <Secondary transfer roller>

[0091] The secondary transfer roller 351 is configured as an example of the roller 6 of the present invention.

[0092] The secondary transfer roller 351 is as follows Figure 3 to Figure 5 (A) As shown in Figure 5(B) and other figures, it includes the following structure, which includes: a shaft 61; an elastic layer 62 and a surface layer 63 provided on the shaft 61; and an annular member 64 as an example of an annular component, which is respectively installed in the shaft 61 in a state of contact with the end face 62e of the elastic layer 62, and has two end portions 61a, 61b protruding from the two end faces 62e of the elastic layer 62 in the axial direction D.

[0093] In FIG. 4(A) and FIG. 4(B), reference numeral 65 indicates a non-conductive bracket, which is used to hold the two end portions 61a, 61b of the shaft 61 and to mount the secondary transfer roller 351 as a whole on a mounting portion such as a support frame not shown. Reference numeral 66 indicates a two-stage gear, which includes a gear for the secondary transfer roller 351 to receive the rotational power transmitted from the rotation drive device not shown, and a relay gear for relaying the rotational power to a rotating part other than the secondary transfer roller 351. Reference numeral 67 indicates a non-conductive cover, which covers the gap between the shielding bracket 65 and the annular member (64) described later.

[0094] Bearings are arranged in the two brackets 65 to rotatably support the two end portions 61a and 61b of the shaft 61, and a power supply member (not shown) is arranged in the bracket 65 on one side of the cover 67. The power supply member contacts the shaft 61 to supply the secondary transfer voltage from the power supply device 15. When the secondary transfer roller 351 is installed, the power supply member contacts and is connected to the power supply member from the power supply device 15.

[0095] The shaft 61 is a substantially cylindrical member having a required diameter and length as a whole, and is made of a conductive material such as stainless steel (SUS).

[0096] As shown in FIG. 6(A) and the like, the shaft 61 in the first embodiment has a stepped portion formed at the ends 61a and 61b where the annular member 64 is mounted, and the stepped portion includes a large diameter portion 612 and a small diameter portion 613 that have different outer diameters. The large diameter portion 612 has the same diameter as the portion where the elastic layer 62 is provided. The small diameter portion 613 is a portion with a smaller outer diameter than the large diameter portion 612. The elastic layer 62 and the surface layer 63 are omitted in FIG. 6(A).

[0097] 5(A) and 5(B), 6(A), etc., the shaft 61 is further formed with a second small diameter portion 614 having an outer diameter smaller than the small diameter portion 613 and a third small diameter portion 615 having an outer diameter smaller than the second small diameter portion 614, outside the small diameter portion 613. The second small diameter portion 614 and the third small diameter portion 615 are used for mounting the bracket 65 and the bearing.

[0098] When performing the secondary transfer, a secondary transfer voltage of 5 kV to 7 kV is supplied to the shaft 61 via a power supply member (not shown) located in the holder 65 .

[0099] The elastic layer 62 is an elastically deformable layer having a desired layer thickness, and is formed using a conductive foam material (conductive foamed epichlorohydrin rubber / nitrile rubber (ECO / NBR)) or the like.

[0100] The elastic layer 62 in the first embodiment is formed by slightly leaving both ends of the large diameter portion 612 of the shaft 61. The elastic layer 62 has a volume resistivity of, for example, 10 6 Ω·cm~10 9 The method is configured to be within the range of Ω·cm.

[0101] The surface layer 63 is a surface layer for imparting necessary functions such as mold release properties.

[0102] The surface layer 63 in the first embodiment is formed as a release layer using a material such as polyimide to cover the outer peripheral surface of the elastic layer 62. The surface layer 63 has a volume resistivity of, for example, 10 8 Ω·cm~10 12 The method is configured to be within the range of Ω·cm.

[0103] 5(A) and 5(B) etc., the surface layer 63 is formed in a state of protruding by a desired length from both end portions 61a, 61b of the elastic layer 62. Reference numeral 63b in FIG. 5(A) and 5(B) etc. indicates the protruding portion of the surface layer 63.

[0104] The annular member 64 is a non-conductive (volume resistivity: 10 15 Ω·cm or more), is also called a collar. The annular member 64 is formed into a desired shape using a material such as polyformaldehyde (POM) molding material (M90-44).

[0105] The annular member 64 in the first embodiment is constituted as a two-stage member having a small diameter portion 641 and a large diameter portion 642 as shown in Fig. 5(B) and Fig. 6(B), and the small diameter portion 641 and the large diameter portion 642 are respectively embedded in the small diameter portion 613 and the large diameter portion 612 of the step portion of the shaft 61. A small diameter mounting hole (cavity) 643 is formed on the inner side of the small diameter portion 641 so that the small diameter portion 613 of the shaft 61 can be embedded. A large diameter mounting hole (recess) 644 is formed on the inner side of the large diameter portion 642 so that the large diameter portion 612 of the shaft 61 can be embedded. A tapered surface 645 including a slope extending from the small diameter mounting hole 643 toward the large diameter mounting hole 644 is formed at the boundary portion of the small diameter mounting hole 643 and the large diameter mounting hole 644 as shown in Fig. 7(A) and Fig. 7(B).

[0106] Furthermore, according to the research of the present inventors, when the roller 60X of Comparative Example 1 is used as the secondary transfer roller 351, the following problem has been confirmed: the roller 60X of Comparative Example 1 is, for example, as shown in FIG. 15(A), a comparative annular member 640 which is different only in that it is not stepped is installed at the end of the shaft 61 in a state of contact with the end surface 62e of the elastic layer 62 instead of the annular member 64. In addition, the annular member 640 at this time is firmly installed at one end of the shaft 61 by press-fitting or the like.

[0107] That is, when the roller 60X of Comparative Example 1 is used as the secondary transfer roller 351 to which a secondary transfer voltage of about 5 kV to 7 kV is supplied, discharge may occur after a certain period of time (e.g., more than 100 hours). It is presumed that the discharge occurs from the shaft 61 of the roller 60X toward the intermediate transfer belt 31.

[0108] Furthermore, by examining the roller 60X where the discharge occurs, it can be confirmed that, as shown in FIG. 15(B), there is a small gap 100 that reaches the shaft 61 between the annular member 640 and the end surface 62e of the elastic layer 62. The gap 100 at this time can be considered to be generated as shown in FIG. 15(B) because the annular member 640 slightly deviates from the end surface 62e of the elastic layer 62 in the axial direction D. Moreover, the gap 100 is generated in a manner that exists throughout the entire area of ​​the annular member 640 in the circumferential direction.

[0109] Therefore, in the roller 6 as the secondary transfer roller 351, as shown in FIG. 6(A) and FIG. Figure 6(B) to Figure 9(A) As shown in Figure 9(B), a fixing portion 71 for fixing the installation position of the annular member 64 in the axial direction D is provided at the parts of the two end portions 61a, 61b of the shaft 61 where the annular member 64 is installed, and a fixed portion 73 fixed by the fixing portion 71 of the shaft 61 is provided at a part of the inner circumferential surface (614a) of the annular member 64 in the axial direction D.

[0110] As shown in FIG. 6A and other figures, the portion of the shaft 61 where the annular member 64 is mounted is a stepped portion including a large diameter portion 612 and a small diameter portion 613 , and therefore the fixing portion 71 is provided in the small diameter portion 613 of the stepped portion.

[0111] The fixing portion 71 in the first embodiment is formed as a groove (an example of a recessed portion) that is continuous over the entire circumferential direction of the small diameter portion 613 of the shaft 61, as shown in FIG6(A) and FIG8(A). The circumferential direction is a direction that is substantially orthogonal to the axial direction D (intersecting at an angle of 90°±1°). Moreover, the groove of the fixing portion 71 is an annular groove that is continuous over the entire circumferential direction of the small diameter portion 613 with a desired width w1 and depth d1 and includes a substantially quadrilateral cross-sectional shape.

[0112] On the other hand, as shown in Figure 6(B) and the like, since the annular member 64 is in a two-section shape having a small diameter portion 641 and a large diameter portion 642, and the portion of the small diameter portion 613 provided with the fixing portion 71 mounted on the shaft 61 is the small diameter portion 641, the fixed portion 73 is the inner circumferential surface 641a of the small diameter mounting hole 643 provided in the small diameter portion 641.

[0113] The fixed portion 73 has a shape that is inserted into the groove of the fixing portion 71 of the shaft 61 so as not to be displaced at least in the axial direction D. The fixed portion 73 is provided at a position such that when inserted into the groove of the fixing portion 71 of the shaft 61, the end surface 64e of the large diameter portion 642 of the annular member 64 is in contact with the end surface 62e of the elastic layer 62.

[0114] As shown in Fig. 6(B), Fig. 7(A), Fig. 7(B), Fig. 8(B), etc., the fixed portion 73 in the first embodiment is formed in a plurality (three in this example) at intervals in the circumferential direction of the inner peripheral surface 641a in the small diameter portion 641 of the annular member 64. Furthermore, the fixed portion 73 is formed as a plate-like protrusion (an example of a convex portion) that protrudes from the inner peripheral surface 641a in the small diameter portion 641 with a desired width w2 and height h1, and extends in a circular arc shape with a desired length m in the circumferential direction.

[0115] At this time, the width w2 of the fixed portion 73 is slightly narrower than the width w1 of the groove of the fixing portion 71. Moreover, the height h1 of the fixed portion 73 is slightly lower than the depth d1 of the groove of the fixing portion 71, for example, a value of about 0.01 mm to 0.06 mm. Furthermore, since three fixed portions 73 are provided at intervals in the circumferential direction of the inner peripheral surface 641a in the small diameter portion 641, the length m of one fixed portion 73 is a length shorter than 1 / 3 of the circumference of the inner peripheral surface 641a (for example, a length of about 1 / 18).

[0116] In the roller 6 as the secondary transfer roller 351 of the first embodiment, the inner peripheral surface of the annular member 64 other than the portion forming the fixed portion 73 is formed as a press-fit portion 75 that is press-fitted into the end portions 61 a and 61 b ​​of the shaft 61 .

[0117] Here, since a fixed portion 73 is formed on the portion along the circumferential direction of the inner circumferential surface 641a in the small diameter portion 641, the portion of the inner circumferential surface of the annular member 64 of embodiment 1 other than the portion forming the fixed portion 73 is the inner circumferential surface 642a of the large diameter portion 642, rather than the inner circumferential surface 641a of the small diameter portion 641.

[0118] Furthermore, the press-fitting means that the press-fitting portion 75 of the annular member 64 is pressed by applying pressure to thereby install it on the installation portion of the shaft 61. Therefore, the press-fitting portion 75 is configured in the following manner, that is, as shown in, for example, FIG. 8(A) and FIG. 8(B), the inner diameter Di of the inner peripheral surface 642a of the press-fitting large diameter portion 642 of the annular member 64 is set to be the same size as or slightly smaller than the outer diameter De of the large diameter portion 612 of the shaft 61 as the installation target portion, and is made of a material that can deform and temporarily expand the diameter of the large diameter portion 642 without being damaged when a force of a certain value or more is applied to the annular member 64.

[0119] Furthermore, in the roller 6 serving as the secondary transfer roller 351 of embodiment 1, as shown in Figures 7(A) and 7(B), Figure 8(B), etc., a protrusion 80 inserted into the end surface 62e of the elastic layer 62 is provided on the end surface 64e of the annular member 64 that contacts the elastic layer 62.

[0120] As shown in FIG. 8(B) , the protrusion 80 in the first embodiment is a portion having the following shape, that is, from the portion of the annular member 64 that contacts the end face 62e of the elastic layer 62, that is, the end face 64e of the large diameter portion 642, the protrusion 80 protrudes approximately parallel to the axial direction D with a thickness t1 (< t2) thinner than the thickness t2 of the end face 64e. The thickness t1 of the protrusion 80 can be set to, for example, 1 / 2 of the thickness t2 of the end face 64e of the annular member 64.

[0121] Moreover, the protrusion 80 is formed as a protrusion of a shape that is continuous in an annular shape on the annular end surface 64e of the annular member 64, as shown in Fig. 7(A) and Fig. 7(B). Furthermore, the protrusion 80 is provided at a position that does not contact the shaft 61 when the annular member 64 is installed, as shown in Fig. 9(A) and Fig. 9(B). In the first embodiment, the protrusion 80 is provided at a position substantially in the middle of the thickness direction of the end surface 64e of the large diameter portion 642, as shown in Fig. 7(A) and Fig. 7(B), Fig. 8(B), etc.

[0122] The roller 6 as the secondary transfer roller 351 is assembled, for example, in the following order.

[0123] First, the annular member 64 is attached to the large diameter portion 612 and the small diameter portion 613 of the shaft 61 of the secondary transfer roller 351. The secondary transfer roller 351 is a roller in which the elastic layer 62 and the surface layer 63 are provided in this order in a predetermined range of the large diameter portion 612 of the shaft 61.

[0124] At this time, the annular member 64 has its small diameter portion 641 attached to the small diameter portion 613 of the shaft 61 substantially simultaneously with the large diameter portion 642 of the annular member 64 being press-fitted into the large diameter portion 612 of the shaft 61 .

[0125] In particular, when the small diameter portion 641 of the annular member 64 is installed on the small diameter portion 613 of the shaft 61, as shown in Figures 9(A) and 9(B), the fixed portion 73 including three protrusions is embedded in the fixed portion 71 in the shape of a continuous groove located in the small diameter portion 613 of the shaft 61, and the three protrusions are located on the inner circumferential surface 641a of the small diameter portion 641 of the annular member 64.

[0126] Thus, the three fixed portions 73 of the annular member 64 contact the left and right groove side wall surfaces of the groove-shaped fixing portion 71 of the shaft 61 in the axial direction D, and are prevented from moving in the axial direction D. As a result, the annular member 64 is not displaced in the axial direction D relative to the shaft 61 and is held in a fixed state, and as a result, the annular member 64 is held in contact with the end surface 62e of the elastic layer 62.

[0127] When the large diameter portion 642 of the annular member 64 is mounted on the large diameter portion 612 of the shaft 61, as shown in Fig. 9(A) and Fig. 9(B), the end face 64e of the large diameter portion 642 is in contact with the end face 62e of the elastic layer 62 in a state where the protrusion 80 bites into the end face 62e of the elastic layer 62. At this time, the protrusion 80 is inserted by elastically deforming a part of the end face 62e of the elastic layer 62 in such a manner that it is pushed inward along the axial direction D.

[0128] Therefore, compared with the case where the annular member 64 is not fixed in a state where the end face 64e of the large diameter portion 642 is in contact with the end face 62e of the elastic layer 62, and the protrusion 80 is not provided on the annular member 64, the end face 64e of the annular member 64 is maintained in a state of being crimped to the end face 62e of the elastic layer 62, and it is more difficult to generate a gap between the end face 62e of the elastic layer 62.

[0129] Moreover, since the protrusion 80 is formed as a protrusion with a circularly continuous shape on the end face 64e of the large diameter portion 642 of the annular member 64, the protrusion 80 will be inserted into the circular end face 62e of the elastic layer 62 in a continuous and uninterrupted state, and therefore, it is more difficult for the annular member 64 to generate a gap between the end face 62e of the elastic layer 62.

[0130] Moreover, since the protrusion 80 is arranged at a position that does not contact the shaft 61 when the annular member 64 is installed, even if the elastic layer 62 is elastically deformed due to the insertion of the protrusion 80, it is difficult to peel off from the peripheral surface of the shaft 61 (large diameter portion 612), and there is no risk of a new gap being generated between the end face 64e of the large diameter portion 642 of the annular member 64 and the outer peripheral surface of the shaft 61.

[0131] Furthermore, when the large diameter portion 642 of the annular member 64 is mounted on the large diameter portion 612 of the shaft 61 , the large diameter portion 642 is mounted in a pressed-fit state because the inner peripheral surface 642 a of the large diameter portion 642 is configured as the press-fit portion 75 .

[0132] As a result, the annular member 64 is difficult to move in the axial direction D of the shaft 61, and the engagement of the fixing portion 71 and the fixed portion 73 prevents the annular member 64 from moving in the axial direction D, thereby maintaining the annular member 64 in a state of being firmly mounted relative to the axial direction D. Furthermore, the annular member 64 is also difficult to move in the circumferential direction of the shaft 61, and is maintained in a state of being firmly mounted.

[0133] Then, as shown in Fig. 4(A) and Fig. 4(B), after the bracket 65 having a bearing is mounted on one end 61a of the shaft 61, the cover 67 is mounted in a state of substantially surrounding the bracket 65 from the outside. Furthermore, after the secondary transfer roller 351 has the two-stage gear 66 mounted on the other end 61b thereof, the bracket 65 is mounted in a state of being inserted into the inner side of the outer gear of the two-stage gear 66. Thus, the secondary transfer roller 351 is completed as a roller 6 having the appearance shown in Fig. 4(A) and Fig. 4(B).

[0134] Then, the completed secondary transfer roller 351 is mounted on the mounting portion of the secondary transfer device 35 of the image forming apparatus 1. When the secondary transfer roller 351 is formally installed at the secondary transfer position in the image forming apparatus 1, the shaft 61 is energized by the power supply device 15.

[0135] Furthermore, it has been confirmed that: for the roller 6 serving as the secondary transfer roller 351, when a secondary transfer voltage of about 5 kV to 7 kV is supplied from the power supply device 15 and the roller 6 is used for a certain period of time (for example, more than 100 hours) in the secondary transfer process, compared with a case where the fixing portion 71 is not provided on the shaft 61 and the fixed portion 73 is not provided on the annular member 64, the phenomenon of discharge occurring through the gap generated between the annular member 64 and the elastic layer 62 is suppressed.

[0136] Furthermore, the secondary transfer roller 351 at this time was inspected, and as shown in FIG9(A), it was confirmed that there was no gap between the annular member 64 and the end surface 62e of the elastic layer 62. In addition, in the secondary transfer roller 351, both ends of the surface layer 63 had protruding portions 63b protruding outward from the end surface 62e of the elastic layer 62, so that discharge caused by the gap between the annular member 64 and the end surface 62e of the elastic layer 62 was unlikely to occur.

[0137] Furthermore, in the image forming apparatus 1 in which the secondary transfer roller 351 including the roller 6 is applied to the secondary transfer device 35, the phenomenon that discharge occurs in the secondary transfer roller 351 through the gap between the annular member 64 and the elastic layer 62 due to factors such as time is suppressed, and thus the occurrence of secondary failures due to the discharge is also suppressed. The secondary failures in this case are, for example, problems such as ignition of the foaming material such as the elastic layer 62 in the secondary transfer roller 351.

[0138] [Implementation Method 2]

[0139] 10(A) and 10(B) show the roller 6B as the secondary transfer roller 351 according to the second embodiment.

[0140] The roller 6B as the secondary transfer roller 351 of the second embodiment includes the same structure as the roller 6 of the first embodiment except that the annular member 64B without the protrusion 80 is used as the annular member 64.

[0141] When the annular member 64B is installed on the shaft 61, the secondary transfer roller 351 including the roller 6B is in a state where the end face 64e of the large diameter portion 642 of the annular member 64B is in direct surface contact with the end face 62e of the elastic layer 62, and is not inserted with the aid of the protrusion 80 as the annular member 64 in embodiment 1 (refer to Figures 9(A) and 9(B), etc.). Except for this difference, the annular member 64B is installed on the shaft 61 (large diameter portion 612 and small diameter portion 613) in the same state.

[0142] That is, the annular member 64B has its small diameter portion 641 attached to the small diameter portion 613 of the shaft 61 substantially at the same time as its large diameter portion 642 is press-fitted into the large diameter portion 612 of the shaft 61 .

[0143] In particular, when the small diameter portion 641 of the annular member 64B is installed on the small diameter portion 613 of the shaft 61, as shown in Figures 10(A) and 10(B), the fixed portion 73 including three protrusions is embedded in the fixed portion 71 of the continuous groove shape located on the small diameter portion 613 of the shaft 61, and the three protrusions are located on the inner circumferential surface 641a of the small diameter portion 641 of the annular member 64B.

[0144] When the large diameter portion 642 of the annular member 64B is mounted on the large diameter portion 612 of the shaft 61, as shown in FIG. 10(A) and FIG. 10(B), the large diameter portion 642 is mounted in a state where the press-fit portion 75 of the inner peripheral surface 642a is press-fitted.

[0145] Furthermore, in the secondary transfer roller 351 including the roller 6B, as in the case of the roller 6 in embodiment 1, the phenomenon of discharge occurring through the gap generated between the annular member 64B and the elastic layer 62 is suppressed compared to the case where the fixing portion 71 is not provided on the shaft 61 and the fixed portion 73 is not provided on the annular member 64B.

[0146] For reference, when the roller 60Y of comparison example 2 is used as the secondary transfer roller 351, the following problem is confirmed. The roller 60Y of comparison example 2, as shown in Figure 16(A), replaces the annular member 64B with a comparative annular member. The comparative annular member is divided into two parts: a first annular member 640Y having a fixed portion 73 and a second annular member 640Z having a pressed portion 75. The annular members are installed on one end of the shaft 61 in such a way that the first annular member 640Y is in contact with the end face 62e of the elastic layer 62 and the second annular member 640Z is in contact with the first annular member 640Y.

[0147] That is, when the roller 60Y of Comparative Example 2 is used as the secondary transfer roller 351 to which a secondary transfer voltage of about 5 kV to 7 kV is supplied, discharge may occur after a certain period of time (for example, 100 hours or more) has passed.

[0148] Furthermore, by examining the roller 60Y where the discharge occurs, it can be confirmed that, as shown in Fig. 16(B), there is a small gap 101 between the first annular member 640Y and the second annular member 640Z, which reaches the shaft 61. The gap 101 at this time can be considered to be generated by the second annular member 640Z slightly deviating in the axial direction D in a manner away from the first annular member 640Y as shown in Fig. 16(B).

[0149] In addition, in the roller 60Y at this time, no gap is generated between the first annular member 640Y and the end surface 62 e of the elastic layer 62 .

[0150] [Implementation method 3]

[0151] 12(A) and 12(B) show a part of a roller 6C serving as a secondary transfer roller 351 according to the third embodiment.

[0152] As shown in Figures 12(A) and 12(B), the roller 6C of embodiment 3 has the same structure as the roller 6B of embodiment 2 except that the fixing portion 71 is provided on the large diameter portion 612 of the shaft 61C, the fixed portion 73 is provided on the inner peripheral surface 642a of the large diameter portion 642 of the annular member 64C, and the small diameter portion 641 is configured as a press-fit portion 75.

[0153] The fixing portion 71 provided on the large diameter portion 612 of the shaft 61C is a groove-shaped fixing portion including substantially the same structure (FIG. 8(A)) as the fixing portion 71 in Embodiment 1, as shown in FIG. 12(A). Furthermore, the fixed portion 73 provided on the inner peripheral surface 642a of the large diameter portion 642 of the annular member 64C is three fixed portions including substantially the same structure (FIG. 8(B)) as the fixed portion 73 in Embodiment 1, as shown in FIG. 12(B).

[0154] Furthermore, the annular member 64C is configured such that the inner peripheral surface 641 a of the small diameter portion 641 is press-fitted into a press-fit portion 75 of the small diameter portion 613 of the shaft 61C.

[0155] The annular member 64C in the roller 6C has its large diameter portion 642 mounted on the large diameter portion 612 of the shaft 61C, and its small diameter portion 641 is press-fitted into the small diameter portion 613 of the shaft 61C substantially at the same time.

[0156] In particular, when the large diameter portion 642 of the annular member 64C is mounted on the large diameter portion 612 of the shaft 61C, the three fixed portions 73 located on the inner circumferential surface 642a of the large diameter portion 642 of the annular member 64C are embedded in the continuous groove-shaped fixing portion 71 located on the large diameter portion 612 of the shaft 61C.

[0157] When the small diameter portion 641 of the annular member 64C is mounted on the small diameter portion 613 of the shaft 61C, the small diameter portion 641 is mounted in a state where the press-fit portion 75 of the inner peripheral surface 641 a of the small diameter portion 641 is press-fitted.

[0158] Furthermore, in the secondary transfer roller 351 including the roller 6C, as in the case of the roller 6B in embodiment 2, the phenomenon of discharge occurring through the gap generated between the annular member 64C and the elastic layer 62 is suppressed compared to the case where the fixing portion 71 is not provided on the shaft 61C and the fixed portion 73 is not provided on the annular member 64C.

[0159] [Implementation Method 4]

[0160] Fig.13 A part of the roller 6D serving as the secondary transfer roller 351 according to the fourth embodiment is shown.

[0161] The roller 6D of the fourth embodiment is as follows Fig.13 As shown in Figures 14(A) and 14(B), an axis 61D is used in which the length of the small diameter portion 613 of the groove-shaped fixing portion 71 is lengthened, and a cylindrical annular member 64D that is not a two-stage shape is used. A fixed portion 73 is provided on the portion of the annular member 64D close to the end face 64e in contact with the elastic layer 62, and the portion away from the end face 64e is changed to be a pressed portion 75. Other than this, it includes the same structure as the roller 6C of embodiment 3.

[0162] The press-fit portion 75 is configured, for example, by setting the inner diameter Di of the inner peripheral surface 64a of the annular member 64C to the same size as the outer shape Df of the small diameter portion 613 of the shaft 61D.

[0163] The annular member 64D in the roller 6D is attached to the small diameter portion 613 of the shaft 61D with a certain end portion of the end surface 64e in contact with the elastic layer 62 as the leading end.

[0164] In particular, when the portion of the annular member 64D close to the end face 64e is installed on the small diameter portion 613 of the shaft 61D, the three fixed portions 73 located on the inner circumferential surface 64a of the annular member 64D are embedded in the continuous groove-shaped fixing portion 71 located on the small diameter portion 613 of the shaft 61D.

[0165] When the portion of the annular member 64D on the side away from the end surface 64e is mounted on the small diameter portion 613 of the shaft 61D, the annular member 64D is mounted in a state where the press-fit portion 75 on the inner peripheral surface 64a is press-fitted.

[0166] In the secondary transfer roller 351 including the roller 6D, similarly to the roller 6C of Embodiment 3, the phenomenon of discharge through the gap between the annular member 64D and the elastic layer 62 is suppressed, compared with the case where the fixing portion 71 is not provided on the shaft 61D and the fixed portion 73 is not provided on the annular member 64D. That is, when the annular member 64D having the integral structure is used, the generation of the gap 101 ( FIG. 16(B) ) as in the roller 60Y of Comparative Example 2 is suppressed.

[0167] [Modifications]

[0168] The present invention is not limited to the contents illustrated in the first to fourth embodiments, and various modifications can be made without departing from the gist of the invention described in each claim. Therefore, the present invention also includes the following modifications.

[0169] The annular member 64 , the annular member 64B, and the annular member 64D in the first embodiment, the second embodiment, and the fourth embodiment may omit the press-fit portion 75 .

[0170] In addition, when the press-fit portion 75 is omitted, it is preferable to adopt a structure that prevents the annular member 64, the annular member 64B, and the annular member 64D from moving (rotating) in the circumferential direction on the shaft 61 and the shaft 61D to which they are installed. Examples of the structure that prevents the movement in the circumferential direction include: a structure in which the fixing portion 71 is set to a shape that prevents the fixed portion 73 from moving in the circumferential direction (a shape that roughly matches the fixed portion 73); or a structure in which a rod-shaped member that stops rotation is inserted into a groove along the axial direction D provided on both the shaft 61 and the shaft 61D and the annular member 64, the annular member 64B, and the annular member 64D.

[0171] The roller 6 of the present invention may also have the annular member 64, the annular member 64B, the annular member 64C, and the annular member 64D mounted on one of the two end portions 61a and 61b of each shaft 61. Furthermore, the roller 6 of the present invention may also have a structure without the surface layer 63. Furthermore, when the surface layer 63 is provided, the protrusion 63e of the surface layer 63 may be omitted.

[0172] Furthermore, the roller 6 of the present invention is not limited to the case where it is applied to the secondary transfer roller 351, and can also be applied as other rollers that supply a voltage that may cause discharge to the shaft 61. Examples of other rollers include a primary transfer roller, a charging roller, a secondary transfer counter roller, and a developing roller provided with an elastic layer.

[0173] Furthermore, the image forming apparatus to which the roller 6 etc. of the present invention is applied may be any image forming apparatus to which the roller 6 etc. of the present invention is applied, and its form, type, image forming method, etc. are not particularly limited.

Claims

1. A roller comprising: Conductive shaft; an elastic layer, disposed on the shaft; as well as A non-conductive annular member is mounted on at least one of the two end portions of the shaft protruding from both end surfaces of the elastic layer in the axial direction in a state of contact with the end surface of the elastic layer. The portions of the shaft at both ends where the annular member is mounted are provided with fixing portions for fixing the mounting position of the annular member in the axial direction. A fixed portion fixed by the fixing portion of the shaft is provided on a portion of the inner peripheral surface of the annular member in the axial direction. The fixed portion is configured to be embedded in a plurality of protrusions of the fixing portion, The parts of the two ends of the shaft where the annular component is installed are two-stage stepped parts including a small diameter part and a large diameter part. The annular component is a two-stage component having a small diameter part and a large diameter part, and the small diameter part and the large diameter part are respectively installed on the small diameter part and the large diameter part of the stepped part of the shaft.

2. The roller according to claim 1, wherein A portion of the inner peripheral surface of the annular member other than a portion forming the fixed portion is configured as a press-fit portion that is press-fitted into the end portion of the shaft.

3. The roller according to claim 1, wherein The fixing portion is provided at the small diameter portion of the step portion of the shaft portion, The fixed portion is provided on the inner peripheral surface of the small diameter portion of the annular member.

4. The roller according to claim 1, wherein The fixing portion is provided at the large diameter portion of the stepped portion of the shaft portion. The fixed portion is provided on the inner peripheral surface of the large diameter portion of the annular member.

5. The roller according to claim 3, wherein The large diameter portion of the annular member is configured as a press-fit portion that is press-fitted into the large diameter portion of the shaft.

6. The roller according to claim 4, wherein The small diameter portion of the annular member is configured as a press-fit portion that is press-fitted into the small diameter portion of the shaft.

7. A roller according to any one of claims 1 to 6, wherein The fixing portion is configured as a recessed portion.

8. A roller according to any one of claims 1 to 6, wherein The end surface of the annular member in contact with the elastic layer is provided with a protrusion that is inserted into the end surface of the elastic layer.

9. An image forming device, comprising: A roller having a conductive shaft, an elastic layer provided on the shaft, and a non-conductive annular member, wherein the non-conductive annular member is attached to at least one of two end portions of the shaft protruding from both end surfaces of the elastic layer in the axial direction; as well as A power supply component supplies voltage to the shaft of the roller, The roller comprises the roller according to any one of claims 1 to 8.

Images