Image forming apparatus

Abstract

The invention relates to an image forming apparatus capable of simply positioning a transfer unit holding a transfer member with respect to an image forming apparatus main body and supplying power to the transfer member. The image forming apparatus is provided with a secondary transfer roller (89) (transfer member) for transferring an image to a sheet (P) (transfer target), and a secondary transfer unit (60) (transfer unit) rotatably supported on an image forming apparatus main body (1) about a support shaft (50a) and holding the secondary transfer roller (89). In addition, a power supply unit (110) capable of outputting a secondary transfer bias voltage (transfer bias voltage) applied to the secondary transfer roller (89), and a compression spring (93) (biasing member) for biasing the secondary transfer unit (60) such that the secondary transfer unit (60) comes into contact with a positioning portion (23a) of the image forming apparatus main body (1) are provided. The compression spring (93) functions as a part or all of a power supply path for supplying the secondary transfer bias voltage from the power supply unit (110) to the secondary transfer roller (89).

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine or a printing machine thereof provided with a transfer member such as a secondary transfer roller. Background Art

[0002] Conventionally, in image forming devices such as copiers and printers, a known technique is to apply force to a transfer unit that holds a secondary transfer roller (transfer member) by a force-applying member so that the transfer unit abuts against a positioning portion of the image forming device body, thereby positioning the transfer unit relative to the image forming device body (for example, refer to Patent Document 1).

[0003] On the other hand, the technology disclosed in Patent Document 2 is to supply power from a power supply unit to a powered component such as a secondary transfer roller by causing a power supply terminal provided on the main body cover to come into contact with the powered component in conjunction with the closing of the main body cover.

[0004] In a conventional image forming apparatus, since a component for positioning a transfer unit holding a transfer member on a main body of the image forming apparatus and a component for supplying power to the transfer member are separately provided, the apparatus becomes complicated and the cost increases.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of easily positioning a transfer unit holding a transfer member relative to a main body of the image forming apparatus and supplying power to the transfer member.

[0006] [Patent Document 1] (Japan) Patent Publication No. 2019-133008

[0007] [Patent Document 2] (Japan) Patent No. 4368663 Summary of the invention

[0008] The image forming device in the present invention includes: a transfer component, which is used to transfer an image to a transfer body; a transfer unit, which is rotatably supported with respect to a support shaft relative to a main body of the image forming device and holds the transfer component; a power supply unit, which can output a transfer bias voltage applied to the transfer component, and a force-applying component, which applies force to the transfer unit so that the transfer unit abuts against a positioning portion of the main body of the image forming device, and the force-applying component acts as a part or all of the power supply path of the transfer bias voltage from the power supply unit to the transfer component.

[0009] According to the present invention, it is possible to provide an image forming apparatus capable of easily positioning a transfer unit holding a transfer member relative to a main body of the image forming apparatus and supplying power to the transfer member. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention.

[0011] Figure 2 (A) and (B) are schematic diagrams showing the action of opening and closing the cover.

[0012] Figure 3 Shown is a diagram of the vicinity of the secondary transfer unit.

[0013] Figure 4 FIG. 1 is a diagram showing the vicinity of a secondary transfer unit as a modified example. DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their detailed descriptions are appropriately omitted.

[0015] First, through Figure 1 The overall configuration and operation of the image forming apparatus 1 will be described.

[0016] like Figure 1 As shown, the image forming apparatus 1 in this embodiment is a tandem color printer. In a tank storage portion 101 located above the image forming apparatus body 1, four toner tanks 102Y, 102M, 102C, and 102K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably arranged (replaceable).

[0017] An intermediate transfer unit 85 is disposed below the tank storage unit 101. Image forming units 4Y, 4M, 4C, and 4K corresponding to respective colors (yellow, magenta, cyan, and black) are arranged in parallel to face an intermediate transfer belt 78 (intermediate transfer body) of the intermediate transfer unit 85.

[0018] A paper feed unit 12 (paper feed cassette) is provided below the image forming apparatus main body 1 to store a plurality of sheets P such as paper in a stacked manner.

[0019] Furthermore, an opening and closing cover 50 for exposing the interior of the image forming apparatus 1 (the conveyance paths K0 and K1 of the sheet P, the fixing device 20 , etc.) is openably and closably provided on the left side of the image forming apparatus 1 .

[0020] Photosensitive drums 5Y, 5M, 5C, 5K are provided in the imaging units 4Y, 4M, 4C, 4K. In addition, charging units 75, developing devices 76, cleaning devices 77, and static elimination units (not shown) are provided around the photosensitive drums 5Y, 5M, 5C, 5K. Then, after the imaging process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drums 5Y, 5M, 5C, 5K, images of different colors are formed on the surfaces of the photosensitive drums 5Y, 5M, 5C, 5K.

[0021] The photosensitive drums 5Y, 5M, 5C, and 5K are driven by the main motor. Figure 1 Then, at the position of the charging section 75, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged (ie, a charging process).

[0022] Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser beam from the exposure unit 3 (writing unit), and electrostatic latent images corresponding to the respective colors are formed by exposure scanning at the position (ie, exposure process).

[0023] Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76 , and at this position, the electrostatic latent image is developed to form a toner image of each color (ie, a developing step).

[0024] After that, the surfaces of the photosensitive drums 5Y, 5M, 5C, 5K reach a position facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, 79K, and the toner images on the photosensitive drums 5Y, 5M, 5C, 5K are transferred to the intermediate transfer belt 78 at this position (i.e., the primary transfer process). At this time, a small amount of untransferred toner still remains on the surfaces of the photosensitive drums 5Y, 5M, 5C, 5K.

[0025] Afterwards, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position opposite to the cleaning device 77, and at this position, the cleaning scraper of the cleaning device 77 mechanically recovers the untransferred colorant remaining on the photosensitive drums 5Y, 5M, 5C, and 5K (i.e., the cleaning process).

[0026] Finally, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach positions facing the static eliminating sections, and the residual potential on the photosensitive drums 5Y, 5M, 5C, and 5K is eliminated at the positions.

[0027] In this way, a series of imaging processes on the photosensitive drums 5Y, 5M, 5C, and 5K are completed.

[0028] After that, the toner images of the respective colors formed on the surfaces of the photosensitive drums after the development process are superimposed on the surface of the intermediate transfer belt 78 (intermediate transfer body). Thus, a color image is formed on the surface of the intermediate transfer belt 78.

[0029] Here, the intermediate transfer unit 85 is composed of an intermediate transfer belt 78 as an intermediate transfer body, four primary transfer bias rollers 79Y, 79M, 79C, 79K, a secondary transfer support roller 82, a cleaning support roller 83, a tension roller 84, an intermediate transfer cleaning device 80, etc. The intermediate transfer belt 78 is stretched and supported by three rollers 82-84, and is also rotated by a roller 82 connected to a main motor. Figure 1 Move in the direction of the arrow.

[0030] The four primary transfer bias rollers 79Y, 79M, 79C, and 79K respectively sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C, and 5K to form a primary transfer nip. A primary transfer bias having a polarity opposite to that of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.

[0031] Then, the intermediate transfer belt 78 moves in the direction of the arrow and passes through the primary transfer nip of each primary transfer bias roller 79Y, 79M, 79C, and 79K in sequence. In this way, the toner images of each color on the photosensitive drums 5Y, 5M, 5C, and 5K are superimposed on the surface of the intermediate transfer belt 78 and are primarily transferred (this is a primary transfer process).

[0032] After that, the intermediate transfer belt 78, to which the toner images of each color are superimposed and transferred primarily, arrives at a position facing the secondary transfer roller 89 as a transfer member. At this position, the secondary transfer backup roller 82 and the secondary transfer roller 89 (transfer member) sandwich the intermediate transfer belt 78 to form a secondary transfer nip. Then, the 4-color toner image formed on the intermediate transfer belt 78 is transferred (secondary transfer) to the sheet P transported to the position of the secondary transfer nip (secondary transfer process). At this time, untransferred toner that has not been transferred to the sheet P still remains on the intermediate transfer belt 78.

[0033] Thereafter, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning device 80. Then, at this position, the untransferred toner on the intermediate transfer belt 78 is recovered.

[0034] In this way, a series of transfer processes on the intermediate transfer belt 78 are completed.

[0035] Here, the sheet P conveyed to the position of the secondary transfer nip is conveyed from the paper feed unit 12 disposed below the apparatus body 1 through the conveyance path K0 and the like.

[0036] Specifically, a plurality of sheets of paper or the like are stacked and stored in the paper feed section 12. Then, when the paper feed roller 31 is moved Figure 1 When the sheet P is driven to rotate counterclockwise in the conveying path K0, the uppermost sheet P sandwiched between the paper feed roller 31 and the friction pad 32 is guided by the guide plate forming the conveying path K0 and is also fed toward the roller gap of the registration roller pair 33 (timing roller pair).

[0037] The sheet P conveyed to the registration roller pair 33 (timing roller pair) temporarily stops at the roller nip (nipping portion) of the registration roller pair 33 whose rotational drive is stopped. Then, after timing with the color image on the intermediate transfer belt 78, the registration roller pair 33 is driven to rotate, and the sheet P as the transfer object is conveyed toward the secondary transfer nip. In this way, the desired color image is transferred to the sheet P.

[0038] After that, at the position of the secondary transfer nip, the sheet P with the color image transferred thereto is transported to the position of the fixing device 20 via the transport path. Then, at this position (the fixing nip formed by the fixing belt 21 and the pressure roller 22 being pressed together), the toner image carried on the surface is fixed to the sheet P by heat and pressure (i.e., the fixing process).

[0039] After that, the sheet P after the fixing process passes through the conveying path K2 and is discharged to the outside of the apparatus by the discharge roller pair 40. The sheets P discharged to the outside of the apparatus by the discharge roller pair 40 are sequentially stacked on the stacking unit 100 as output images.

[0040] In this way, a series of image forming processes in the image forming apparatus are completed.

[0041] Below, use Figure 2 , Figure 3 etc., the characteristic configuration and operation of the image forming apparatus 1 in this embodiment will be described in detail.

[0042] As previously used Figure 1 As described above, the opening and closing cover 50 for opening and closing the inside of the image forming apparatus 1 is provided on the left side of the image forming apparatus 1 in the present embodiment.

[0043] Here, refer to Figure 2 (A) and (B) of the image forming apparatus 1, the opening and closing cover 50 is configured to be rotatable around the support shaft 50a in order to open and close the interior of the image forming apparatus 1. The secondary transfer unit 60 (which holds the secondary transfer roller 89, etc.) described later is held in the opening and closing cover 50. Therefore, the secondary transfer unit 60 is linked to the opening and closing action of the opening and closing cover 50, and rotates together with the opening and closing cover 50 around the support shaft 50a.

[0044] Specifically, if Figure 2 (A)(and Figure 1 ) as shown, when the closed opening and closing cover 50 and the secondary transfer unit 60 are together as shown in FIG. Figure 2 When the image forming device 1 rotates counterclockwise (in the direction of the arrow) around the support shaft 50a as shown in (B), a portion of the interior of the image forming device 1 (conveying paths K0, K1, secondary transfer unit 60, fixing device 20, etc.) is opened (exposed), so that the sheet P jammed in the conveying paths K0, K1, fixing device 20, etc. can be removed, or the secondary transfer unit 60 and fixing device 20 can be loaded and unloaded to perform maintenance.

[0045] In addition, if Figure 2 As shown in (B), when the opening and closing cover 50 and the secondary transfer unit 60 are opened, the support shaft 50a is used as the center. Figure 2 When the clockwise rotation of Figure 2 (A) Figure 3 As shown, the opening and closing cover 50 is in a closed state, and the secondary transfer roller 89 is in contact with the intermediate transfer belt 78 to form a secondary transfer nip.

[0046] Here, as previously used Figure 1 As described above, the image forming apparatus 1 of the present embodiment is provided with the secondary transfer roller 89 as a transfer member for transferring an image onto the sheet material P as a transfer target.

[0047] The secondary transfer roller 89 as the transfer member is a roller member that contacts the intermediate transfer belt 78 as an intermediate transfer body to form a secondary transfer nip, and secondarily transfers the image primarily transferred to the intermediate transfer belt 78 to the sheet P as a transfer target body conveyed to the secondary transfer nip.

[0048] The secondary transfer roller 89 is formed of a shaft portion 89a (see Figure 3 The elastic layer of the secondary transfer roller 89 may be formed in a solid or foamed sponge form by dispersing conductive fillers such as carbon in a rubber material such as polyurethane, EPDM, silicone, or by making it contain an ionic conductive material.

[0049] In addition, refer to Figure 3 The image forming apparatus 1 of the present embodiment is provided with a power supply unit 110 that can output a transfer bias (secondary transfer bias) to be applied to the secondary transfer roller 89 (transfer member).

[0050] The power supply unit 110 applies a secondary transfer bias voltage with a polarity different from that of the colorant to the secondary transfer roller 89, thereby forming a secondary transfer electric field at the position of the secondary transfer clamping portion, so that the colorant carried on the outer peripheral surface (colorant carrying surface) of the intermediate transfer belt 78 is electrostatically moved toward the side of the secondary transfer roller 89.

[0051] In addition, the secondary transfer bias may be a DC voltage or an AC voltage superimposed on a DC voltage.

[0052] In addition, refer to Figure 3 (and Figure 2 ), in the image forming apparatus 1 of the present embodiment, a secondary transfer unit 60 is provided as a transfer unit that holds a secondary transfer roller 89 (transfer member).

[0053] The secondary transfer unit 60 (transfer unit) is supported relative to the image forming apparatus main body 1 so as to be rotatable around the support shaft 50a. Figure 2 As described above, the secondary transfer unit 60 is held by the openable and closable cover 50 that is rotatable (openable and closable) about the support shaft 50 a.

[0054] Furthermore, in the secondary transfer unit 60 , in addition to the holding portion 61 that rotatably holds the secondary transfer roller 89 , a transport guide member 62 that guides the sheet P fed out from the secondary transfer nip is provided.

[0055] The conveying guide component 62 of the secondary transfer unit 60 is arranged on the downstream side of the sheet conveying direction relative to the secondary transfer clamping portion, and is arranged on the upstream side of the sheet conveying direction relative to the fixing entrance guide component 23 of the fixing device 20. It is a component for guiding the sheet P after the secondary transfer process sent out from the secondary transfer clamping portion to the fixing device 20 (fixing entrance guide component 23).

[0056] The holding portion 61 of the secondary transfer unit 60 holds a bearing (not shown) that rotatably holds the shaft portion 89a of the secondary transfer roller 89 so that a portion of the secondary transfer roller 89 is accommodated in its recess (a portion recessed away from the secondary transfer nip).

[0057] In addition, the secondary transfer unit 60 (holding portion 61) is provided with a fitting member 90 that fits with the shaft portion 89a of the secondary transfer roller 89, and a second compression spring 91 that acts as a second urging member to urge the fitting member 90 so that the secondary transfer roller 89 abuts against the intermediate transfer belt 78 (intermediate transfer body). The fitting member 90 fits with the groove portion (provided with the second compression spring 91) formed in the holding portion 61, and can be Figure 3The groove portion slides and moves in the left-right direction (the direction in which the groove portion extends, which is the direction approaching or leaving the intermediate transfer belt 78).

[0058] Here, refer to Figure 3 In the image forming apparatus 1 of this embodiment, a compression spring 93 (first compression spring) is provided as a biasing member for biasing the secondary transfer unit 60 in such a manner that the secondary transfer unit 60 (transfer unit) contacts the positioning portion 23a of the image forming apparatus body 1.

[0059] Specifically, the positioning portion 23a is formed in the width direction ( Figure 3 The end portion (in the direction perpendicular to the paper surface) is formed so as to protrude downward.

[0060] On the other hand, in the conveyance guide member 62 of the secondary transfer unit 60 , a contact portion 62 a (a portion protruding in a convex shape in the width direction) that contacts the positioning portion 23 a is formed at an end portion in the width direction.

[0061] Then, the secondary transfer unit 60 is moved toward the left by the compression spring 93 provided at the end in the width direction. Figure 3 By applying a force diagonally to the upper right, the contact portion 62a of the secondary transfer unit 60 contacts the positioning portion 23a, and the position of the secondary transfer unit 80 in the image forming device 1 is determined with high precision. Therefore, the position of the secondary transfer nip is determined with high precision, so that a good secondary transfer process is performed. Furthermore, the position of the conveying guide member 62 in the image forming device 1 is also determined with high precision, and the conveying performance of the sheet P from the secondary transfer nip to the fixing nip is also improved.

[0062] In addition, such components related to the positioning of the secondary transfer unit 60 (compression spring 93, contact portion 62a, positioning portion 23a, etc.) are provided at both ends in the width direction.

[0063] In order to effectively perform the above-mentioned positioning, it is preferable to configure the urging direction of the compression spring 93 and the direction in which the contact portion 62 a contacts the positioning portion 23 a to coincide with each other.

[0064] In the present embodiment, the secondary transfer unit 60 is held in the opening and closing cover 50 so as to be movable in the direction of approaching or separating from the intermediate transfer belt 78. Then, the compression spring 93 is provided on the main body of the opening and closing cover 50 (indirectly provided on the image forming apparatus main body 1), and in the opening and closing cover 50, the secondary transfer unit 60 is urged in the above-mentioned direction.

[0065] On the other hand, the secondary transfer unit 60 may be fixed to the opening and closing cover 50, and the compression spring 93 may be directly provided on the image forming apparatus main body 1 without the opening and closing cover 50. In this case, the overall positioning of the opening and closing cover 50 is determined by the contact between the contact portion 62a of the secondary transfer unit 60 and the positioning portion 23a.

[0066] In the present embodiment, the positioning portion 23 a against which the contact portion 62 a of the secondary transfer unit 60 contacts is provided on the fixing inlet guide member 23 of the fixing device 20 , but the position (member) where the positioning portion is provided is not limited thereto.

[0067] Here, the compression spring 93 (first compression spring) as the urging member in the present embodiment functions as a part of a power supply path for supplying the secondary transfer bias from the power supply unit 110 to the secondary transfer roller 89 (transfer member).

[0068] In detail, the compression spring 93 is made of a conductive material such as metal, and one end side thereof is connected to the power supply unit 110 via a first power supply path 94 (for example, made of a wire harness, etc.). In addition, the fitting component 90 and the second compression spring 91 of the secondary transfer unit 60 (holding portion 61) described above are formed of a conductive material such as metal or a conductive resin. Furthermore, a conductive plate 92 is provided in the secondary transfer unit 60 (holding portion 61). One end side of the conductive plate 92 is connected to the second compression spring 91 (second force applying member), and the other end side is connected to a contact portion 93a (having conductivity and a certain degree of rigidity) formed on the other end side of the compression spring 93.

[0069] With such a configuration, the secondary transfer bias (transfer bias) output from the power supply unit 110 (first power supply path 94 ) is applied to the shaft portion 89 a of the secondary transfer roller 89 via the compression spring 93 , the conductive plate 92 , the second compression spring 91 (second biasing member), and the fitting member 90 .

[0070] Furthermore, regardless of the positioning of the secondary transfer unit 60 , components serving only as power supply paths (mainly the conductive plate 92 and the first power supply path 94 ) are not provided at both widthwise end portions but only at one widthwise end portion.

[0071] Thus, in this embodiment, the compression spring 93 (force-applying component) having the function of positioning the secondary transfer unit 60 on the image forming device body 1 is also used as a power supply path for applying a secondary transfer bias from the power supply unit 110 to the secondary transfer roller 89. Therefore, compared with the case where a component having a positioning function and a component having a power supply function are separately provided, the image forming device 1 becomes simplified and cost-effective.

[0072] It should also be noted that the compression spring 93 (biasing member) functions as a part of the power supply path for providing the secondary transfer bias from the power supply unit 110 to the secondary transfer roller 89, but the compression spring can also be directly connected to the secondary transfer roller, etc., so that it functions as the entire power supply path.

[0073] <Modification>

[0074] like Figure 4 As shown, in the secondary transfer unit 60 (transfer unit) of the modified example, a neutralizing member 70 for neutralizing the sheet P fed out from the secondary transfer nip is provided between the conveyance guide member 62 and the holding portion 61 that rotatably holds the secondary transfer roller 89 .

[0075] The static removing member 70 has a needle-shaped static removing plate 70 a at the front end thereof for removing charges accumulated on the sheet P after the secondary transfer process, thereby reducing the problem of the sheet P being electrostatically attracted to the conveyance guide member 62 .

[0076] Then, in this modification, the compression spring 93 having the function of positioning the secondary transfer unit 60 also has the function of determining the position of the neutralizing member 70 in the image forming apparatus 1. Therefore, the neutralizing function of the neutralizing member 70 can be well exerted.

[0077] As described above, the image forming apparatus 1 in this embodiment is provided with a secondary transfer roller 89 (transfer member) for transferring an image to a sheet P (a transfer object), and a secondary transfer unit 60 (transfer unit) rotatably supported on the image forming apparatus main body 1 around the support shaft 50a and holding the secondary transfer roller 89. In addition, a power supply unit 110 capable of outputting a secondary transfer bias (transfer bias) applied to the secondary transfer roller 89, and a compression spring 93 (biasing member) for biasing the secondary transfer unit 60 in such a manner that the secondary transfer unit 60 abuts against the positioning portion 23a of the image forming apparatus main body 1 are provided. Then, the compression spring 93 functions as a part or all of a power supply path for supplying the secondary transfer bias from the power supply unit 110 to the secondary transfer roller 89.

[0078] This makes it possible to easily position the secondary transfer unit 60 holding the secondary transfer roller 89 (transfer member) relative to the image forming apparatus main body 1 and to easily supply power to the secondary transfer roller 89 .

[0079] In addition, in this embodiment, although the present invention is applied to a color image forming apparatus 1, the present invention can also be applied to a monochrome image forming apparatus. In this case, the transfer member to which the present invention is applied is a transfer roller or the like that contacts a photosensitive body such as a photosensitive drum and forms a transfer nip portion for conveying a sheet as a transfer object.

[0080] In this embodiment, the secondary transfer roller 89 is used as the transfer member to which the present invention is applied, but the primary transfer bias rollers 79Y, 79M, 79C, and 79K may also be used as the transfer member to which the present invention is applied. In this case, the transfer target to which the image is transferred by the transfer member is the intermediate transfer belt 78.

[0081] In the present embodiment, the secondary transfer roller 89 that contacts the intermediate transfer belt 78 to form a transfer nip is used as a transfer member to which the present invention is applied. However, a secondary transfer charger that faces the intermediate transfer belt 78 without contacting it may be used.

[0082] In the present embodiment, the compression spring 93 is used as the urging member having the positioning function and the power supply function, but the urging member is not limited thereto, and for example, a leaf spring or the like may be used.

[0083] However, even in such a case, the same effects as those of the present embodiment can be obtained.

[0084] Furthermore, the present invention is not limited to this embodiment, and within the scope of the technical concept of the present invention, in addition to the teachings of this embodiment, it is obvious that this embodiment can be appropriately changed. In addition, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and appropriate number, position, shape, etc. can be selected when implementing the present invention.

[0085] In addition, the embodiment of the present invention can also be a combination of, for example, the following additional notes 1 to 11.

[0086] <Additional Note 1>

[0087] An image forming device, comprising:

[0088] A transfer component for transferring an image to a transfer object;

[0089] A transfer unit, which is supported rotatably around a support shaft relative to the image forming apparatus main body and holds the transfer member;

[0090] a power supply unit capable of outputting a transfer bias voltage applied to the transfer member, and

[0091] a force applying member for applying force to the transfer unit so that the transfer unit abuts against a positioning portion of the image forming apparatus body,

[0092] The urging member functions as a part or the entirety of a power supply path for the transfer bias from the power source to the transfer member.

[0093] <Note 2>

[0094] The image forming apparatus according to Supplementary Note 1, characterized in that:

[0095] The transfer member is a secondary transfer roller, which abuts against the intermediate transfer body to form a secondary transfer nip, and secondary transfers the image primarily transferred to the intermediate transfer body to a sheet as the transfer object conveyed to the secondary transfer nip.

[0096] The urging member is a compression spring made of a conductive material.

[0097] <Addendum 3>

[0098] The image forming device according to Supplement 2, characterized in that the transfer unit comprises:

[0099] an engaging member engaged with the shaft portion of the secondary transfer roller;

[0100] a second urging member for urging the engaging member so that the secondary transfer roller abuts against the intermediate transfer body, and

[0101] A conductive plate, one end of which is connected to the second force applying member, and the other end of which is connected to the compression spring.

[0102] The transfer bias output from the power supply section is applied to the secondary transfer roller via the compression spring, the conductive plate, the second urging member, and the fitting member.

[0103] <Note 4>

[0104] The image forming device according to Supplementary Note 2 or Supplementary Note 3 is characterized in that:

[0105] The transfer unit includes a conveying guide member for guiding the sheet fed out from the secondary transfer nip.

[0106] The transport guide member is formed with a contact portion that contacts the positioning portion.

[0107] <Addendum 5>

[0108] The image forming apparatus according to Supplementary Note 4 is characterized in that:

[0109] The transfer unit includes a static eliminating member for eliminating static electricity of the sheet fed out from the secondary transfer nip, provided between the conveyance guide member and a holding portion that rotatably holds the secondary transfer roller.

Claims

1. An image forming device, characterized in that include: A transfer component for transferring an image to a transfer object; A transfer unit, which is supported rotatably around a support shaft relative to the image forming apparatus main body and holds the transfer member; a power supply unit capable of outputting a transfer bias voltage applied to the transfer member, and a force applying member for applying force to the transfer unit so that the transfer unit abuts against a positioning portion of the image forming apparatus body, The urging member functions as a part or the entirety of a power supply path for the transfer bias from the power source to the transfer member.

2. The image forming device according to claim 1, wherein: The transfer member is a secondary transfer roller, which abuts against the intermediate transfer body to form a secondary transfer nip, and secondary transfers the image primarily transferred to the intermediate transfer body to a sheet as the transfer object conveyed to the secondary transfer nip. The urging member is a compression spring made of a conductive material.

3. The image forming device according to claim 2, characterized in that The transfer unit comprises: an engaging member engaged with the shaft portion of the secondary transfer roller; a second urging member for urging the engaging member so that the secondary transfer roller abuts against the intermediate transfer body, and A conductive plate, one end of which is connected to the second force applying member, and the other end of which is connected to the compression spring. The transfer bias output from the power supply section is applied to the secondary transfer roller via the compression spring, the conductive plate, the second urging member, and the fitting member.

4. The image forming apparatus according to claim 2, wherein: The transfer unit includes a conveying guide member for guiding the sheet fed out from the secondary transfer nip. The transport guide member is formed with a contact portion that contacts the positioning portion.

5. The image forming apparatus according to claim 4, wherein: The transfer unit includes a static eliminating member for eliminating static electricity of the sheet fed out from the secondary transfer nip, provided between the conveyance guide member and a holding portion that rotatably holds the secondary transfer roller.

Images