Image forming device

Abstract

To provide an image forming device capable of easily changing an installation form of a transformer.SOLUTION: An image forming device 1 comprises: a frame 7 to which an image forming unit PU can be mounted; a board 200; and first to fourth output electrodes 101, 102, 103, 104 that can be electrically connected to one of first to fourth transformers 81, 82, 83, 84 supported by the board and output voltage to each of first to fourth electrifiers 54K, 54C, 54Y, 54M. The frame comprises: first to fourth housing sections 71, 72, 73, 74 capable of individually housing the first to fourth transformers; and a cover mounting section 18 for mounting a cover 20 for supporting a relay terminal 4 that is electrically connected to at least two electrodes of the second to fourth output electrodes and is electrically connected to the fourth transformer, and for covering at least one portion of the housing sections while extending over at least two housing sections of the second to fourth housing sections with the board.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] For example, as described in Patent Document 1, in a conventional image forming apparatus, an image forming unit having a photosensitive member and a charger for charging the photosensitive member is mounted on a frame disposed inside the apparatus body. A high-voltage power supply board having a transformer mounted thereon is disposed opposite the image forming unit across the frame. The transformer has a connection electrode, and an output electrode is connected to the connection electrode. The output electrode outputs a voltage to the charger, thereby charging the charger.

[0003] The image forming apparatus disclosed in Patent Document 1 is equipped with two molded transformers. The installation configuration, including the number of transformers, varies depending on the voltage control performance required of the image forming apparatus, the constraints on the space available for arranging the transformers, the charging method, and other factors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-194534 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the image forming apparatus with the above-described configuration did not have a frame configuration that assumed that the installation configuration of the transformers could be changed, so that, for example, when changing the number of transformers, it was necessary to change not only the configuration of the high-voltage power supply board, but also the frame, the configuration of the connection wires from the transformers to the output electrodes, etc., resulting in low compatibility. For example, there was a problem in that it was not easy to change models between an image forming apparatus with two transformers and an image forming apparatus with four transformers.

[0006] SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an image forming apparatus in which the installation form of the transformer can be easily changed. [Means for solving the problem]

[0007] (1) To achieve the above-mentioned object, according to one embodiment of the present disclosure, there is provided an image forming apparatus comprising: an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers that charge the first to fourth photosensitive members, respectively, and that forms an image on a recording medium; a frame to which the image forming unit can be attached; a substrate disposed opposite the image forming unit across the frame; and first to fourth output electrodes that are electrically connectable to any of the first to fourth transformers supported on the substrate and output voltages to the first to fourth chargers, respectively; the frame further comprising: first to fourth housing sections that can individually house the first to fourth transformers; and a cover mounting section that supports a relay terminal that electrically connects two or more of the second to fourth output electrodes and is electrically connected to the fourth transformer, and that is configured to mount a cover between the frame and the substrate, the cover spanning two or more of the second to fourth housing sections and covering at least a portion of the housing sections.

[0008] In this image forming apparatus, the connection between the output electrode and the transformer can be changed depending on whether the cover supporting the relay terminal is attached to the cover attachment portion of the frame or not. That is, the frame is configured to accommodate the first to fourth housing portions and the cover attachment portion, and is designed to accommodate switching of the transformer installation configuration. Therefore, when the image forming apparatus undergoes a model change, the installation configuration of the transformer can be easily changed, resulting in an image forming apparatus with high compatibility.

[0009] (2) In the image forming apparatus of the above aspect, the relay terminal may be electrically connected to the second to fourth output electrodes and also to the fourth transformer, and the cover may straddle the second to fourth housing sections and cover at least a portion of the second to fourth housing sections.

[0010] According to the image forming apparatus of this aspect, the first output electrode can be configured to meet specifications such as controlling the voltage independently of the other second to fourth output electrodes.

[0011] (3) In the image forming apparatus of the above aspect, the first output electrode may be electrically connected to the first transformer, the second output electrode may be electrically connected to the second transformer, the third output electrode may be electrically connected to the third transformer, and the fourth output electrode may be electrically connected to the fourth transformer.

[0012] According to the image forming apparatus of this aspect, the first to fourth output electrodes are connected to the first to fourth transformers, respectively, so that the voltages of the first to fourth output electrodes can be controlled independently.

[0013] (4) In the image forming apparatus of the above aspect, the cover may be attached to the cover attachment portion of the frame.

[0014] According to the image forming apparatus of this aspect, by attaching the cover to the frame, two or more of the second to fourth output electrodes can be electrically connected to the fourth transformer via the relay terminal.

[0015] (5) In the image forming apparatus of the above aspect, the first output electrode is electrically connected to the first transformer, and the second to fourth output electrodes are electrically connected to the fourth transformer, and the second transformer and the third transformer may not be provided.

[0016] According to the image forming apparatus of this aspect, it is possible to provide two transformers, the first transformer and the fourth transformer.

[0017] (6) In the image forming apparatus of the above aspect, the first to fourth housing sections may include housing ribs that surround at least a portion of the periphery of the first to fourth transformers that can be housed therein, respectively.

[0018] In this image forming apparatus, the housing ribs can easily separate and form the housing sections, and the housing ribs can ensure an insulation distance between the transformers housed in adjacent housing sections and improve the strength of the frame.

[0019] (7) In the image forming apparatus of the above aspect, the relay terminal may have a curved portion for climbing over the receiving rib.

[0020] With this type of image forming device, when the cover is attached to the frame, the curved portion of the relay terminal overcomes the accommodating rib, preventing interference between the accommodating rib and the relay terminal, and allowing the cover to be easily attached to the frame.

[0021] (8) In the image forming apparatus of the above aspect, the cover may have a groove that accommodates the curved portion.

[0022] With this type of image forming device, even if the relay terminal has a curved portion and is bent in each section as a whole, the curved portion can be accommodated in the groove of the cover, so the relay terminal can be easily supported by the cover.

[0023] (9) In the image forming apparatus of the above aspect, the cover mounting portion may include an engaging portion that engages with an engaged portion of the cover.

[0024] According to the image forming apparatus of this aspect, the cover can be easily attached to the cover attachment portion due to the engagement structure between the engaging portion and the engaged portion.

[0025] (10) In the image forming apparatus of the above aspect, the engaged portion may include a plurality of holes, and at least one of the holes may be an elongated hole.

[0026] According to this type of image forming apparatus, the rotation of the cover can be prevented by the plurality of holes, and the oblong holes can absorb dimensional errors with the engaging portions, allowing the cover to be suitably positioned relative to the frame.

[0027] (11) In the image forming apparatus of the above aspect, a duct for circulating air inside the image forming unit may be provided, and the first and fourth transformers may be disposed above the duct.

[0028] According to the image forming apparatus of this aspect, the image forming unit can be cooled by the duct, and the first and fourth transformers can be suitably disposed above the duct.

[0029] (12) In the image forming apparatus of the above aspect, the first transformer may have a first connection electrode, and the first connection electrode may be in direct contact with the first output electrode.

[0030] According to this form of image forming apparatus, the first transformer and the first output electrode can be configured to be in direct contact via the first connection electrode of the first transformer, and the voltage of the first output electrode can be controlled independently.

[0031] (13) In the image forming apparatus of the above aspect, a metal plate may be provided to position the first to fourth photosensitive members, the fourth transformer may be disposed between the fourth output electrode and the metal plate, and the frame may have an insulating rib between the fourth transformer and the metal plate.

[0032] According to the image forming apparatus of this aspect, the insulating rib can provide suitable insulation between the fourth transformer and the metal plate.

[0033] (14) In the image forming apparatus of the above aspect, a metal plate may be provided to position the first to fourth photosensitive bodies, the first transformer may be disposed between the first output electrode and the metal plate, and the frame may have an insulating rib between the first transformer and the metal plate.

[0034] According to the image forming apparatus of this aspect, the insulating rib can provide suitable insulation between the first transformer and the metal plate.

[0035] (15) An image forming apparatus according to a second aspect of the present disclosure includes an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers that charge the first to fourth photosensitive members, respectively, and that forms an image on a recording medium; a frame to which the image forming unit can be attached; and first to fourth output electrodes that can be electrically connected to any of the first to fourth transformers and output voltages to the first to fourth chargers, respectively, wherein the frame includes first to fourth housing sections that can individually house the first to fourth transformers, and a mounting section to which a support frame can be attached that electrically connects two or more of the second to fourth output electrodes and supports a relay terminal that is electrically connected to the fourth transformer.

[0036] In this image forming apparatus, the connection between the output electrode and the transformer can be changed depending on whether the support frame supporting the relay terminal is attached to the attachment portion of the frame or not. That is, the frame is configured to accommodate the first to fourth housing portions and the attachment portion, and is designed to accommodate switching of the transformer installation configuration. Therefore, when the image forming apparatus undergoes a model change, the installation configuration of the transformer can be easily changed, resulting in an image forming apparatus with high compatibility.

[0037] (16) An image forming apparatus according to a third aspect of the present disclosure includes an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers that charge the first to fourth photosensitive members, respectively, and that forms an image on a recording medium; and first to fourth output electrodes that are electrically connectable to any of the first to fourth transformers and output voltages to the first to fourth chargers, respectively, and is characterized in that the image forming apparatus is capable of switching between a first state in which the first to fourth transformers are electrically connected to the first to fourth output electrodes, respectively, and a second state in which only the first transformer and the fourth transformer are provided, the first transformer is electrically connected to the first output electrode, and the fourth transformer is electrically connected to two or more of the second to fourth output electrodes.

[0038] According to this form of image forming device, it is possible to easily switch between a first state in which the first to fourth transformers are electrically connected to the first to fourth output electrodes, respectively, and a second state in which only the first transformer and the fourth transformer are provided, the first transformer is electrically connected to the first output electrode, and the fourth transformer is electrically connected to two or more of the second to fourth output electrodes. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic block diagram of a high-voltage power supply board included in the image forming apparatus according to the first embodiment. [Figure 3]FIG. 2 is an overall perspective view showing a right side frame, a cover, and a transformer. [Figure 4] FIG. 10 is a side view of the right side frame with the cover attached, seen from the right side. [Figure 5] 5 is a cross-sectional view taken along line VV in FIG. 4. [Figure 6] FIG. 10 is a perspective view showing the right side frame without the cover attached. [Figure 7] FIG. [Figure 8] FIG. 10 is a schematic block diagram of a high-voltage power supply board included in an image forming apparatus according to a second embodiment of the present invention. [Figure 9] FIG. 2 is an overall perspective view showing a right side frame and a transformer. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. First Embodiment An image forming apparatus 1 according to a first embodiment of the present invention will be described with reference to FIGS. [Overall configuration of image forming apparatus 1] 1 is a schematic diagram showing the configuration of an image forming apparatus 1 according to a first embodiment. The image forming apparatus 1 is a color laser printer that forms a multi-color image on a sheet S by electrophotography. The sheet S corresponds to an example of a "recording medium."

[0041] In the following description, the left side in Fig. 1 is defined as the front side of the image forming apparatus 1, the right side in Fig. 1 is defined as the rear side of the image forming apparatus 1, the front side of the paper in Fig. 1 is defined as the right side of the image forming apparatus 1, and the back side of the paper in Fig. 1 is defined as the left side of the image forming apparatus 1. In addition, the upper and lower sides in Fig. 1 are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0042] The image forming apparatus 1 includes an apparatus main body 2, a paper feed unit 3, an image forming unit 5, and a high-voltage power supply board 200. The image forming unit 5 forms an image on a sheet S conveyed by the paper feed unit 3.

[0043] The device main body 2 is formed in a substantially rectangular parallelepiped shape and houses the paper feed unit 3 and the image forming unit 5. A front opening 2A is formed in the front of the device main body 2, and the device main body 2 has a front cover 21 that can open and close the front opening 2A.

[0044] The front cover 21 is configured to be rotatable around a rotation shaft 21a at its lower end, and by rotating around the rotation shaft 21a, it can move between a closed position where it closes the front opening 2A and an open position where it opens the front opening 2A. A paper output tray 22 is formed on the top surface of the device body 2, and is inclined downward from the front to the rear.

[0045] The paper feed unit 3 has a paper feed tray 10 that supports the sheets S and a sheet transport unit 30 that transports the sheets S. The paper feed unit 3 is arranged in the lower part of the device main body 2, and transports the sheets S supported in the paper feed tray 10 to the image forming unit 5 by the sheet transport unit 30. The paper feed tray 10 is configured to be slidable in the front-to-rear direction, and is configured to be movable between a storage position where it is stored in the device main body 2 and a separation position where it is pulled out forward from the storage position.

[0046] The sheet conveying section 30 includes a paper feed roller 32, a separation roller 33, a separation pad 33a, a pair of conveying rollers 34, and a pair of registration rollers 35. Within the device main body 2, a conveying path P1 for the sheet S is configured, which runs from the paper feed tray 10 to the paper discharge tray 22 via the image forming section 5.

[0047] The sheets S supported on the paper feed tray 10 are separated one by one by the paper feed roller 32, the separation roller 33, and the separation pad 33a and sent to the conveying path P1. The paper feed roller 32 is a roller that conveys the sheets S from the paper feed tray 10 toward the image forming unit 5. The separation roller 33 and the separation pad 33a constitute a separating means that separates the sheets S supported on the paper feed tray 10 one by one.

[0048] The sheet S sent to the conveying path P1 is conveyed toward the image forming unit 5 by a pair of conveying rollers 34 and a pair of registration rollers 35. The pair of registration rollers 35 regulates the movement of the leading edge of the conveyed sheet S, temporarily stops the sheet S, and then conveys the sheet S toward the image forming unit 5 at a predetermined timing.

[0049] The image forming unit 5 is disposed above the paper feed unit 3 and includes four toner cartridges 50 arranged side by side in the front-to-rear direction, and a photosensitive drum 51 corresponding to each toner cartridge 50. The toner cartridges 50 are arranged corresponding to each color in the order of yellow, magenta, cyan, and black from the front. The toner cartridges 50 are detachably supported in a drawer 59. The drawer 59 can be attached to and detached from the device main body 2 through the front opening 2A in the device main body 2 by opening the front cover 21. The toner cartridges 50 include a developing roller 52. In the following description, when each component is to be distinguished by color, the suffix Y (yellow), M (magenta), C (cyan), or K (black) is added to the reference numeral of each component, and when no distinction is made, the suffix is ​​omitted.

[0050] The photosensitive drum 51 is formed in a generally cylindrical shape with its axis extending in the left-right direction, and is rotatably supported by a drawer 59. The developing roller 52 extends in the left-right direction, and is rotatably supported by a toner cartridge 50. Toner is an example of a developer. The developing roller 52 supplies toner to the photosensitive drum 51.

[0051] The apparatus main body 2 has an exposure device 56 that exposes the surfaces of the photosensitive drums 51. The exposure device 56 includes a laser diode, a polarizer, a lens, and a mirror (not shown). The exposure device 56 is configured to emit a light beam toward each photosensitive drum 51 to expose the surface of each photosensitive drum 51.

[0052] A transfer belt 41 is disposed below the photosensitive drum 51, facing it across the transport path P1. The transfer belt 41 is in contact with the photosensitive drum 51. The transfer belt 41 is stretched between a drive roller 42 and a driven roller 43 disposed in front of the drive roller 42. A transfer roller 44 is disposed at a position facing each photosensitive drum 51 across the transfer belt 41. In the image forming unit 5, the transfer belt 41, the drive roller 42, the driven roller 43, the transfer roller 44, etc. form a belt device 40. The photosensitive drum 51 corresponds to an example of a "photosensitive member."

[0053] The image forming unit 5 is equipped with a charger 54 for charging each photosensitive drum 51. The charger 54 is supported by a drawer 59. The photosensitive drums 51, which have been uniformly charged by the charger 54, are selectively exposed to light by an exposure device 56. This exposure selectively removes charge from the surface of the photosensitive drum 51, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. The charger 54 is a scorotron charger, and uniformly charges the surface of the photosensitive drum 51. The charger 54 may also be a charging roller.

[0054] The toner contained in the toner cartridge 50 is positively charged and carried on the surface of the developing roller 52. A developing bias is applied to the developing roller 52, and when the electrostatic latent image formed on the photosensitive drum 51 faces the developing roller 52, the potential difference between the electrostatic latent image and the developing roller 52 causes toner to be supplied from the developing roller 52 to the electrostatic latent image. As a result, a toner image is formed on the surface of the photosensitive drum 51.

[0055] When the sheet S transported toward the image forming unit 5 reaches the transfer belt 41, it is transported by the transfer belt 41 and passes sequentially between the transfer belt 41 and each photosensitive drum 51. Then, when the toner image carried on the surface of the photosensitive drum 51 faces the sheet S, it is transferred onto the sheet S by a transfer bias applied to the transfer roller 44.

[0056] In this embodiment, the transfer belt 41 is configured as a conveying belt that conveys the sheet S onto which the toner image is transferred, but it can also be configured as an intermediate transfer belt in which the toner image is transferred to the belt itself and the toner image transferred to the belt is further transferred to the sheet S.

[0057] The sheet S onto which the toner image has been transferred is transported to a fixing device 60. The fixing device 60 includes a heating roller 61 and a pressure roller 62 that is in pressure contact with the heating roller 61, and the toner image on the sheet S transported to the fixing device 60 is thermally fixed while the sheet S passes between the heating roller 61 and the pressure roller 62. In other words, the fixing device 60 fixes the toner image on the sheet S.

[0058] The sheet S on which the toner image has been thermally fixed is transported downstream in the transport direction from the fixing device 60. An intermediate paper discharge roller 63a and a driven roller 63b arranged opposite the intermediate paper discharge roller 63a are arranged downstream in the transport direction from the fixing device 60. A paper discharge roller 64a and a driven roller 64b arranged opposite the paper discharge roller 64a are arranged downstream in the transport direction from the intermediate paper discharge roller 63a and the driven roller 63b.

[0059] The sheet S transported downstream in the transport direction from the fixing unit 60 is transported by intermediate discharge rollers 63a and driven rollers 63b, and further transported by discharge rollers 64a and driven rollers 64b, and discharged onto the discharge tray 22.

[0060] In the image forming apparatus 1, a process unit PU that forms a toner image on a sheet S is configured by a drawer 59, a toner cartridge 50 supported by the drawer 59, a photosensitive drum 51, a charger 54, etc. Note that the process unit PU is only required to include at least the photosensitive drums 51 (first photosensitive drum 51K, second photosensitive drum 51C, third photosensitive drum 51Y, fourth photosensitive drum 51M) and chargers 54 (first charger 54K, second charger 54C, third charger 54Y, fourth charger 54M), and may also include a transfer belt 41 or a fixing unit 60. The process unit PU corresponds to an example of an "image forming unit."

[0061] The image forming apparatus 1 includes a power supply board 11 on which a power supply circuit is formed, and a board cover 12 that covers the power supply board 11. The board cover 12 is disposed between the paper feed tray 10 and the belt device 40 at the rear of the apparatus main body 2. The apparatus main body 2 houses the process unit PU and the board cover 12.

[0062] The discharge roller 64a and the intermediate discharge roller 63a are rotatably supported by the device body 2 with their axial directions aligned in the left-right direction. The discharge roller 64a and the intermediate discharge roller 63a extend along their axial directions. The discharge roller 64a is an example of a conveyance roller.

[0063] The discharge rollers 64a and the intermediate discharge rollers 63a are configured to be rotatable in a forward direction, which is the rotation direction when conveying the sheet S toward the discharge tray 22, and in a reverse direction, which is the rotation direction opposite to the forward direction. The image forming apparatus 1 has a re-conveyance path P2 that guides the sheet S, which has been conveyed along the conveyance path P1 and passed through the fixing device 6, to the conveyance path P1 upstream of the registration roller pair 35 in the sheet conveyance direction.

[0064] The re-conveying path P2 branches off from the conveying path P1 at a branching point Pb located between the fixing unit 6 and the intermediate paper discharge roller 63a, then extends forward between the substrate cover 12 and the paper feed tray 10, and merges with the conveying path P1 at a junction point Pa located between the conveying roller pair 34 and the registration roller pair 35.

[0065] The sheet S conveyed from the fixing unit 6 to the discharge rollers 64a can be conveyed again to the image forming unit 5 through the re-conveyance path P2 by rotating the discharge rollers 64a and the intermediate discharge rollers 63a in the reverse direction. The sheet S conveyed to the re-conveyance path P2 by the discharge rollers 64a and the intermediate discharge rollers 63a is conveyed toward the image forming unit 5 by the first re-conveyance roller pair 36 and the second re-conveyance roller pair 37 arranged on the re-conveyance path P2.

[0066] The image forming apparatus 1 is capable of double-sided printing, in which a sheet S, on one side of which an image has been formed in the image forming unit 5, is transported again to the image forming unit 5 via a re-transport path P2, and an image is formed on the other side of the sheet S.

[0067] On the right side of the image forming apparatus 1, a right side frame 7 (see FIGS. 3 to 6), a cover 20 (see FIGS. 3 to 5), and a high-voltage power supply board 200, which will be described later, are arranged in this order from the process unit PU side to the outside. The high-voltage power supply board 200 is attached to the right side frame 7 by an attachment member (not shown). The right side frame 7, the cover 20, and the high-voltage power supply board 200 will be described in detail below.

[0068] A left side frame (not shown) is disposed on the left side of the image forming apparatus 1. That is, the process unit PU is detachably mounted to the right side frame 7 and the left side frame. That is, the process unit PU (image forming unit) can be mounted to the right side frame 7. A high-voltage power supply board 200 is disposed on the side of the right side frame 7 opposite to the side on which the process unit PU is mounted, at a position facing the process unit PU. The right side frame 7 is an example of a "frame," and the cover is an example of a "cover" and a "support frame."

[0069] [Configuration of high-voltage power supply board 200] Next, the configuration of the high-voltage power supply board 200 will be described with reference to Fig. 2. Fig. 2 is a schematic block diagram for explaining the electrical configuration of the high-voltage power supply board 200 provided in the image forming apparatus 1. A main board 9 on which an ASIC 8 is mounted is disposed on the side of the left side frame (not shown) opposite to the side on which the process unit PU is mounted. The main board 9 and the high-voltage power supply board 200 are connected via a signal line FFC.

[0070] The main board 9 is mounted with an ASIC 8 having a CPU 90, a ROM 91, and a RAM 92. The CPU 90 controls the charging voltage generation circuits 23K and 23CMY, which will be described later. The ROM 91 stores the operation program for the entire image forming apparatus 1, and the RAM 92 is used to store image data used in the printing process and to expand the program in the ROM 91.

[0071] The high-voltage power supply board 200 is provided with charge voltage generation circuits 23K and 23CMY. The charge voltage generation circuits 23K and 23CMY are each connected to the ASIC 8 via a signal line FFC. The charge voltage generation circuit 23K is provided with a first transformer 81. The charge voltage generation circuit 23CMY is provided with a fourth transformer 84. The first transformer 81 and the fourth transformer 84 are both molded transformers and include a voltage transformer and a smoothing circuit.

[0072] The process unit PU is provided with a first output electrode 101, a second output electrode 102, a third output electrode 103, and a fourth output electrode 104. The first output electrode 101 is electrically connected to a first transformer 81 and is also electrically connected to a charger 54K (first charger). The second output electrode 102 to the fourth output electrode 104 are electrically connected to a fourth transformer 84. The second output electrode 102 to the fourth output electrode 104 are electrically connected to chargers 54C (second charger), 54M (third charger), and 54Y (fourth charger), respectively.

[0073] The charging voltage generating circuit 23K generates a charging voltage to be applied to the discharge wire 13K of the charger 54K. A connection electrode 810 is disposed in the first transformer 81. A first output electrode 101 is directly connected to the connection electrode 810. The "connection electrode 810" corresponds to an example of a "first connection electrode." The first output electrode 101 is directly connected to the first transformer 81 via the connection electrode 810. The charging voltage generated by the charging voltage generating circuit 23K is output to the first output electrode 101 via the connection electrode 810 of the first transformer 81 under control of the ASIC 8, thereby charging the charger 54K. Here, the charging voltage is, for example, 5.5 kV to 8 kV (positive polarity), and the grid voltage is, for example, approximately 700 V (positive polarity).

[0074] The charging voltage generating circuit 23CMY generates charging voltages to be applied to the discharge wires 13C, 13M, and 13Y of the three chargers 54C, 54M, and 54Y, respectively. A connection electrode 840 is disposed on the fourth transformer 84. The second output electrode 102 to the fourth output electrode 104 are connected to the connection electrode 840. For convenience, only the second output electrode 102 is shown in FIG. 2. The second output electrode 102 to the fourth output electrode 104 are connected to the fourth transformer 84 via the connection electrode 840 and a relay terminal 4 (described later), but are not directly connected like the first output electrode 101 and the first transformer 81. The charging voltages generated by the charging voltage generating circuit 23CMY are output to the output electrodes via the connection electrode 840 of the fourth transformer 84 under control of the ASIC 8, and the chargers 54C, 54M, and 54Y are charged.

[0075] The charging voltage input to the connection electrode 840 is divided, and then the divided charging voltage is applied to the three discharge wires 13C, 13M, and 13Y. The grid voltages of the grids 14C, 14M, and 14Y corresponding to each discharge wire are controlled so that the surfaces of the photosensitive drums 51Y, 51M, and 51C corresponding to each grid are uniformly charged to approximately the same potential (for example, +700V). Here, the charging voltage is, for example, 5.5 kV to 8 kV (positive polarity), and the grid voltage is, for example, approximately 700 V (positive polarity).

[0076] The charging voltage generation circuit 23K generates a charging voltage according to a PWM signal from the PWM1 port of ASIC 8, and the charging voltage is feedback-controlled via the A / D1 port. The charging voltage generation circuit 23CMY generates a charging voltage according to a PWM signal from the PWM2 port of ASIC 8, and the charging voltage is feedback-controlled via the A / D2, A / D3, and A / D4 ports.

[0077] [Right side frame 7 configuration] Next, the configuration of the right side frame 7 will be described. FIG. 3 is an overall perspective view showing the right side frame 7, cover 20, and transformers 81 and 84, and is a view of the right side frame 7 as seen from the cover mounting portion 18 (see FIG. 6) where the cover 20 is mounted. FIG. 4 is a side view of the right side frame 7 with the cover 20 mounted, as seen from the right side. For ease of understanding, the cover 20 is shown cross-hatched in FIG. 4. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 6 is a perspective view of the right side frame 7 without the cover 20 mounted, as seen from the cover mounting portion 18 where the cover 20 is mounted. Note that although the cover 20 is not shown in FIG. 6, the relay terminal 4 supported by the cover 20, which will be described later, is also shown.

[0078] As shown in FIGS. 3 and 6 , the right side frame 7 includes a duct 70, a first housing section 71, a second housing section 72, a third housing section 73, two fourth housing sections 74a and 74b, and a cover mounting section 18. The duct 70 is a flow path for circulating cooling air inside the process unit PU and is formed from front to rear in the approximate center in the vertical direction. The first housing section 71 is a housing space capable of individually housing the first transformer 81. The second housing section 72 is a housing space capable of individually housing the second transformer 82. The third housing section 73 is a housing space capable of individually housing the third transformer 83. The fourth housing section 74 is a housing space capable of individually housing the fourth transformer 84. Here, "housing a transformer" does not necessarily mean that the transformer and the housing section are in contact with each other, and includes a state in which at least a portion of the transformer is located within the space within the housing section.

[0079] The housing sections 71 to 74a, 74b are disposed above the duct 70, and are arranged in the order of the first housing section 71 to the fourth housing section 74a, 74b from rear to front. As described above, the image forming apparatus 1 of the first embodiment has only two transformers 81, 84, and does not have a second or third transformer. Therefore, no transformers are housed in the second housing section 72 or the third housing section 73.

[0080] The second housing section 72 and the third housing section 73 are used to house the second and third transformers when the image forming apparatus 1 of the first embodiment is upgraded to a different model image forming apparatus that further includes a second and third transformer in addition to the first transformer 81 and the fourth transformer 84, for example, an image forming apparatus corresponding to the second embodiment described below that includes four transformers. Hereinafter, the image forming apparatus 1 corresponding to the first embodiment that includes two transformers will also be referred to as a "2-channel image forming apparatus." Furthermore, the image forming apparatus 100 corresponding to the second embodiment described below that includes four transformers will also be referred to as a "4-channel image forming apparatus."

[0081] Each of the accommodating sections 71 to 74a, 74b is provided with an accommodating rib 75 that is arranged to surround the periphery of the corresponding transformer that can be accommodated therein. The accommodating rib 75 stands upright from the bottom of the right side frame 7 and is configured, for example, with a wall-like member that extends in the vertical direction. The bottom of the right side frame 7 is the side that faces the process unit PU. The multiple accommodating ribs 75 divide the space within the right side frame 7, and the corresponding transformer can be accommodated in the space surrounded by the accommodating ribs 75. The accommodating rib 75 not only serves to divide the accommodating sections 71 to 74a, 74b and maintain an insulating distance, but also serves to improve the strength of the right side frame 7.

[0082] Of the two fourth housing sections 74a, 74b, the fourth housing section 74a located on the front side is a housing section for housing the fourth transformer 84 in a 2-channel image forming apparatus 1. The fourth housing section 74b located on the rear side (i.e., the housing section adjacent to the third housing section 73) is a housing section for housing the fourth transformer 84 in a 4-channel image forming apparatus. Therefore, in this embodiment, as shown in FIG. 3, of the two fourth housing sections 74a, 74b, the fourth transformer 84 is housed in the fourth housing section 74a located on the front side. The first housing section 71 houses the first transformer 81.

[0083] As shown in FIG. 6, the cover mounting portion 18 is a portion for mounting the cover 20 between the right side frame 7 and the high-voltage power supply board 200. The cover mounting portion 18 is a portion formed long in the front-rear direction and is formed in the right side frame 7 so as to straddle approximately the lower half of the second housing portion 72, the third housing portion 73, and the rear fourth housing portion 74b in the front-rear direction. A cover 20 (described later) is attached and fixed to the cover mounting portion 18 with bolts 45 (see FIG. 4). The cover mounting portion 18 has two engagement protrusions 76a, 76b extending vertically from the bottom of the right side frame 7. The engagement protrusions 76a, 76b include a front engagement protrusion 76a located near the front end of the cover mounting portion 18 and a rear engagement protrusion 76b located near the rear end of the cover mounting portion 18. Each engagement protrusion 76a, 76b engages with a corresponding hole 16a, 16b (see FIG. 7; described in detail later) formed in the cover 20.

[0084] A front metal plate 77a is disposed at the front end of the right side frame 7 for positioning the front end of the process unit PU within the apparatus body 2. A rear metal plate 77b is disposed at the rear end of the right side frame 7 for positioning the rear end of the process unit PU within the apparatus body 2. Each of the metal plates 77a, 77b has a flat surface in the vertical direction and is fixed to the right side frame 7 with screws. Each of the metal plates 77a, 77b has a locking portion that can lock into an engagement notch (not shown) formed in the drawer 59. When replacing the photosensitive drum 51 or the like, the user can detach the process unit PU from the apparatus body 2, and each of the metal plates 77a, 77b is used to position the process unit PU when it is reattached to the apparatus body 2.

[0085] The fourth transformer 84 is disposed between the front metal plate 77a and the fourth output electrode 104 (see FIG. 4). In the right side frame 7, a front insulating rib 78a is disposed between the fourth transformer 84 and the front metal plate 77a. The first transformer 81 is disposed between the rear metal plate 77b and the first output electrode 101 (see FIG. 4). In the right side frame 7, a rear insulating rib 78b is disposed between the fourth transformer 84 and the front metal plate 77a. Each insulating rib 78a, 78b is a rib for suppressing discharge from the adjacent transformers 81, 84.

[0086] [Cover 20 Configuration] Next, the configuration of the cover 20 will be described. Fig. 7 is an overall perspective view showing the cover 20, as seen from the side facing the right side frame 7 when attached. As shown in Fig. 7, the overall shape of the cover 20 is roughly the shape of a long, shallow, bottomed container that corresponds to the cover attachment portion 18 of the right side frame 7. The relay terminal 4 is supported on the bottom of the cover 20.

[0087] Here, the "bottom of the cover 20" refers to the portion that faces the bottom of the right side frame 7 when the cover 20 is attached to the right side frame 7. The depth of the bottom of the cover 20 is not constant, and the distance between the bottom of the cover 20 and the opposing bottom of the right side frame 7 varies depending on the portion. The cover 20 has an uneven shape in the left-right direction, and covers the entire cover attachment portion 18 when attached to the right side frame 7. The relay terminal 4 is a connection terminal for connecting the second output electrode 102, the third output electrode 103, and the fourth output electrode 104 to the fourth transformer 84. In other words, when the cover 20 is attached to the right side frame 7, the relay terminal 4 is electrically connected to the second output electrode 102 to the fourth output electrode 104, as well as to the fourth transformer 84.

[0088] The relay terminal 4 is fixed by being hooked onto a plurality of hook portions 24 formed on the bottom of the cover 20. The relay terminal 4 has a transformer connection spring portion 25, a second output electrode connection spring portion 26 (hereinafter simply referred to as the "second spring portion"), a third output electrode connection spring portion 27 (hereinafter simply referred to as the "third spring portion"), and a fourth output electrode connection spring portion 28 (hereinafter simply referred to as the "fourth spring portion"). The transformer connection spring portion 25, the fourth spring portion 28, the third spring portion 27, and the second spring portion 26 are connected in this order from the front side. The transformer connection spring portion 25 is connected to a connection electrode 840 of the fourth transformer 84. The second spring portion 26 is connected to the second output electrode 102. The third spring portion 27 is connected to the third output electrode 103. The fourth spring portion 28 is connected to the fourth output electrode 104 .

[0089] 6 and 7, the relay terminal 4 has a first bent portion 29a and a second bent portion 29b for climbing over the accommodating rib 75 formed on the right side frame 7. The first bent portion 29a is located between the second spring portion 26 and the third spring portion 27 and is a portion that climbs over two accommodating ribs 75 that form the boundary between the second accommodating portion 72 and the third accommodating portion 73. The two accommodating ribs 75 that the first bent portion 29a climbs over are partially formed to have a low height so that the first bent portion 29a can easily climb over them.

[0090] The second curved portion 29b is located between the third spring portion 27 and the fourth spring portion 28 and overcomes two housing ribs 75 that form the boundary between the third housing portion 73 and the rear fourth housing portion 74b. The second curved portion 29b protrudes upward from an imaginary line connecting the transformer connecting spring portion 25 and the second spring portion 26 to bypass a protrusion formed on the right side frame 7. A groove 15 that accommodates each of the curved portions 29a and 29b is formed in the cover 20. In this embodiment, the relay terminal 4 has the two curved portions 29a and 29b. However, other curved portions may be appropriately positioned to bypass protrusions or the like formed in the right side frame 7, and the overall shape of the relay terminal 4 may be modified as appropriate.

[0091] A long hole 16b that is long in the front-to-rear direction is provided at the rear end of the cover 20, penetrating the bottom. A circular hole 16a that forms a perfect circle is provided at a position near the front end of the cover 20 and near the fourth spring portion 28, penetrating the bottom. When the cover 20 is attached to the right side frame 7, the rear engagement protrusion 76b of the right side frame 7 is inserted into the long hole 16b, and the front engagement protrusion 76a of the right side frame 7 is inserted into the circular hole 16a. These two holes 16a, 16b prevent the cover 20 from rotating. Furthermore, because one of the holes is the long hole 16b, dimensional errors in the engagement portion between the long hole 16b and the rear engagement protrusion 76b can be absorbed, allowing the cover 20 to be appropriately positioned relative to the right side frame 7. The holes 16a, 16b correspond to an example of an "engaged portion."

[0092] Furthermore, bolt holes 17 are formed in the cover 20 at three positions in the front-to-rear direction: near the front end, approximately in the center, and near the rear end. Bolts 45 (see FIG. 4) for fixing the cover 20 are inserted into the bolt holes 17. When the cover 20 is attached to the right side frame 7, the cover 20 covers roughly the lower half of each of the second housing portion 72, the third housing portion 73, and the rear fourth housing portion 74b across the front-to-rear direction. The cover 20 is an example of a "cover" and a "support frame."

[0093] [Effect] The image forming apparatus 1 of the first embodiment has the above-described configuration and thereby provides the following functions and effects.

[0094] (1) In the image forming apparatus 1 of the first embodiment, the right side frame 7 to which the process unit PU is attached includes first to fourth housing sections 71 to 74 that can individually accommodate the first to fourth transformers 81 to 84, and a cover mounting section 18 for mounting the cover 20. The cover 20 supports a relay terminal 4 that electrically connects the second to fourth output electrodes 102 to 104 and electrically connects the fourth transformer 84. The cover 20 covers at least a portion of each of the second to third housing sections 72, 73, and the rear fourth housing section 74b. Therefore, when the cover 20 is removed, the first to fourth transformers 81 to 84 can be individually accommodated in the first to fourth housing sections 71 to 74 of the right side frame 7.

[0095] For this reason, when upgrading the 2-channel image forming apparatus 1 to, for example, a 4-channel image forming apparatus, first, the cover 20 is removed. More specifically, when the cover 20 is not attached, the connection between the first transformer 81 and the first output electrode 101 is the same as in the 2-channel image forming apparatus 1, and the first transformer 81 is housed in the first housing section 71. Then, the second transformer is newly housed in the second housing section 72, and the connection electrode of the second transformer is connected to the second output electrode 102. Similarly, the third transformer is newly housed in the third housing section 73, and the connection electrode of the third transformer is connected to the third output electrode 103. The fourth transformer is housed in the fourth housing section on the rear side, and the connection electrode of the fourth transformer is connected to the fourth output electrode 104. This allows for easy upgrades to a 4-channel image forming apparatus.

[0096] That is, as described above in detail using the specific example of changing the model from a 2-channel image forming apparatus 1 to a 4-channel image forming apparatus, the image forming apparatus 1 of the first embodiment has a frame configuration that assumes switching of the transformer installation mode. Therefore, although the configuration of the high-voltage power supply board 200 needs to be changed to correspond to the number and installation position of the transformers, the configuration of the right side frame 7 and each output electrode can be applied as is to the image forming apparatus after the model change. In other words, the image forming apparatus 1 can be made highly compatible.

[0097] Here, a state in which only the first transformer 81 and the fourth transformer 84 are provided in the 2-channel image forming apparatus 1, the first transformer 81 is electrically connected to the first output electrode 101, and the fourth transformer 84 is electrically connected to two or more of the second output electrode 102 to the fourth output electrode 104 is referred to as a "second state." On the other hand, a state in which the first transformer 81 to the fourth transformer 84 are electrically connected to the first output electrode 101 to the fourth output electrode 104, respectively, is referred to as a "first state." In this case, it can be said that the image forming apparatus 1 of the first embodiment can be easily switched between the second state and the first state.

[0098] (2) In the image forming apparatus 1 of the first embodiment, the first output electrode 101 is electrically connected to the first transformer 81, and the second output electrode 102 to the fourth output electrode 104 are electrically connected to the fourth transformer 84. The image forming apparatus 1 is a two-channel image forming apparatus that does not have a second transformer or a third transformer, but has only the first transformer 81 and the fourth transformer 84. This makes it possible to provide a suitable configuration that corresponds to specifications and applications where, for example, it is desired to control the voltage of one frequently used color, such as black, independently of the voltage of the other three colors.

[0099] (3) In the image forming apparatus 1 of the first embodiment, the first to fourth storage sections 71 to 74a, 74b are provided with storage ribs 75 that surround at least a portion of the periphery of the first to fourth transformers 81 to 84 that can be stored in the storage sections. Therefore, the storage ribs 75 make it easy to form the storage sections 71 to 74a, 74b. In addition, the strength of the right side frame 7 can be improved.

[0100] (4) In the image forming apparatus 1 of the first embodiment, the relay terminal 4 has the first bent portion 29a and the second bent portion 29b for climbing over the accommodating rib 75. Therefore, when the cover 20 is attached to the right side frame 7, interference between the accommodating rib 75 and the relay terminal 4 can be suppressed, and the cover 20 can be easily attached to the right side frame 7.

[0101] (5) In the image forming apparatus 1 of the first embodiment, the cover 20 has grooves 15 that accommodate the curved portions 29a and 29b. Therefore, even if the relay terminal 4 has a shape that is curved in each position as a whole, it can be easily supported on the bottom of the cover 20.

[0102] (6) In the image forming apparatus 1 of the first embodiment, the cover mounting portion 18 includes engagement protrusions 76a and 76b that engage with the holes 16a and 16b of the cover 20. Therefore, when mounting the cover 20, the engagement protrusions 76a and 76b are inserted into the holes 16a and 16b of the cover 20, thereby easily positioning the cover 20 relative to the right side frame 7. This facilitates the mounting process. Furthermore, the cover 20 has two holes 16a and 16b, one of which is an elongated hole 16b. Therefore, the two holes 16a and 16b can prevent the cover 20 from rotating. Furthermore, the elongated hole 16b can absorb dimensional errors with the rear engagement protrusion 76b, allowing the cover 20 to be appropriately positioned relative to the right side frame 7.

[0103] Second Embodiment Next, an image forming apparatus 100 according to a second embodiment of the present invention will be described with reference to Figures 8 and 9. Note that components substantially similar to those of the first embodiment are designated by the same reference numerals, and descriptions thereof will be omitted. Image forming apparatus 100 according to the second embodiment differs from image forming apparatus 1 according to the first embodiment in that it does not have cover 20 and is a 4-channel image forming apparatus equipped with four transformers: first transformer 81, second transformer 82, third transformer 83, and fourth transformer 84.

[0104] 8 is a schematic block diagram for explaining the electrical configuration of the high-voltage power supply board 200 provided in the image forming apparatus 100. The high-voltage power supply board 200 is provided with charging voltage generation circuits 23K, 23C, 23M, and 23Y. The charging voltage generation circuits 23K, 23C, 23M, and 23Y are each connected to the ASIC 8 via a signal line FFC. The charging voltage generation circuit 23K is provided with a first transformer 81. The charging voltage generation circuit 23C is provided with a second transformer 82. The charging voltage generation circuit 23M is provided with a third transformer 83. The charging voltage generation circuit 23Y is provided with a fourth transformer 84.

[0105] The first to fourth transformers 81 to 84 have connection electrodes 810, 820, 830, and 840, respectively. The first output electrode 101 is electrically connected to the first transformer 81 via the connection electrode 810 and is also electrically connected to the charger 54K. The second output electrode 102 is electrically connected to the second transformer 82 via the connection electrode 820 and is also electrically connected to the charger 54C. The third output electrode 103 is electrically connected to the third transformer 83 via the connection electrode 830 and is also electrically connected to the charger 54M. The fourth output electrode 104 is electrically connected to the fourth transformer 84 via the connection electrode 840 and is also electrically connected to the charger 54Y. In other words, the first to fourth output electrodes 101 to 104 are directly connected to the connection electrodes 810, 820, 830, and 840 of the first to fourth transformers 81 to 84, respectively.

[0106] The charging voltage generation circuit 23K generates a charging voltage according to a PWM signal from the PWM1 port of ASIC8, and the charging voltage is feedback-controlled via the A / D1 port. The charging voltage generation circuit 23C generates a charging voltage according to a PWM signal from the PWM2 port of ASIC8, and the charging voltage is feedback-controlled via the A / D2 port. The charging voltage generation circuit 23M generates a charging voltage according to a PWM signal from the PWM3 port of ASIC8, and the charging voltage is feedback-controlled via the A / D3 port. The charging voltage generation circuit 23Y generates a charging voltage according to a PWM signal from the PWM4 port of ASIC8, and the charging voltage is feedback-controlled via the A / D4 port.

[0107] 9 is an overall perspective view showing the right side frame 7 and transformer provided in the image forming apparatus 100, with the right side frame 7 viewed from the cover mounting portion 18 side. As shown in FIG. 9, the first housing portion 71 houses a first transformer 81. The second housing portion 72 houses a second transformer 82. The third housing portion 73 houses a third transformer 83. Of the two fourth housing portions 74a and 74b, the fourth housing portion 74b located at the rear houses a fourth transformer 84.

[0108] According to the image forming apparatus 100 of the first embodiment, similarly to the image forming apparatus 1 of the first embodiment, the first state and the second state can be easily changed.

[0109] <Other embodiments> In the image forming apparatus 1, 100 of each of the above embodiments, the right side frame 7 has two fourth housing sections 74a, 74b, but if there are no constraints on transformer installation, only one fourth housing section may be used. In this configuration, the fourth housing section can be the same in the 2-channel image forming apparatus 1 and the 4-channel image forming apparatus 100.

[0110] In the image forming apparatus 1 of the first embodiment, the first output electrode 101 is electrically connected to the first transformer 81, and the second output electrode 102 to the fourth output electrode 104 are electrically connected to the fourth transformer 84. However, the fourth transformer 84 may be configured to electrically connect two or more of the second output electrode 102 to the fourth output electrode 104. As a specific modification, for example, the first output electrode 101 may be electrically connected to the first transformer 81, the second output electrode 102 may be electrically connected to the second transformer, and the third output electrode 103 and the fourth output electrode 104 may be electrically connected to the fourth transformer 84. In other words, the number of transformers is not limited to two and may be three.

[0111] As in the above-described modified example, the relay terminal 4 may be configured to electrically connect two or more of the second to fourth output electrodes 104 and to electrically connect to the fourth transformer 84. The cover 20 may be configured to straddle two or more of the second to fourth housing sections 72 to 74 and cover at least a portion of the housing sections.

[0112] In the image forming apparatus 1 of the first embodiment, the engagement structure between the cover mounting portion 18 of the right side frame 7 and the cover 20 is achieved by engaging two engagement protrusions 76a, 76b formed on the cover mounting portion 18 with two holes 16a, 16b formed on the cover 20, but this is not a limitation. For example, holes may be formed on the cover mounting portion 18 side and protrusions may be located on the cover 20 side. Alternatively, the engagement structure may be located in one place, i.e., singular. Furthermore, the image forming apparatus 1 need not have an engagement structure at all.

[0113] In the image forming apparatus 1, 100 of each of the above embodiments, the first transformer 81 to the fourth transformer 84 are arranged above the duct 70, but they may also be arranged below the duct 70.

[0114] In the image forming apparatus 1 of the first embodiment, the first transformer 81 has the connection electrode 810, and the connection electrode 810 is in direct contact with the first output electrode 101. However, the connection electrode 810 does not have to be in direct contact with the first output electrode 101.

[0115] In the image forming apparatus 1, 100 of each of the above embodiments, the right side frame 7 is provided with the front metal plate 77a, the rear metal plate 77b, the front insulating rib 78a, and the rear insulating rib 78b, but these do not necessarily have to be provided.

[0116] The present invention is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present invention. For example, the technical features in each embodiment corresponding to the technical features in the form described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0117] 1,100...image forming apparatus, 2...apparatus main body, 3...paper feed unit, 4...relay terminal, 5...image forming unit, 6...fuser unit, 7...right side frame (frame, support frame), 8...ASIC, 9...main board, 10...paper feed tray, 11...power supply board, 12...board cover, 13K, 13C, 13Y, 13M...discharge wire, 14K, 14C, 14Y, 14M...grid, 15...groove, 16a...circular hole (engaged portion), 16b...oval hole (engaged portion), 17...bolt hole, 18...cover mounting portion, 20...cover, 21...front cover, 21a...rotating shaft, 22...paper output tray, 23K, 23C, 23Y, 23M...Charge voltage generating circuit, 24...Hook portion, 25...Transformer connecting spring portion, 26...Second output electrode connecting spring portion, 27...Third output electrode connecting spring portion, 28...Fourth output electrode connecting spring portion, 29a...First bent portion, 29b...Second bent portion, 30...Sheet conveying portion, 32...Paper feed roller, 33...Separation roller, 33a...Separation pad, 34...Conveying roller pair, 35...Registration roller pair, 36...First re-conveying roller pair, 37...Second re-conveying roller pair, 40...Belt device, 41...Transfer belt, 42...Drive roller, 43...Driven roller, 44...Transfer roller, 50...Toner Cartridge, 51K...photosensitive drum (first photosensitive member), 51C...photosensitive drum (second photosensitive member), 51Y...photosensitive drum (third photosensitive member), 51M...photosensitive drum (fourth photosensitive member), 52...developing roller, 54K...charger (first charger), 54C...charger (second charger), 54Y...charger (third charger), 54M...charger (fourth charger), 56...exposure device, 59...drawer, 60...fixing unit, 61...heating roller, 62...pressure roller, 63a...intermediate paper discharge roller, 63b...driven roller, 64a...paper discharge roller, 64b...driven roller, 70...duct, 71...first storage section, 72 ...second accommodating section, 73...third accommodating section, 74a, 74b...fourth accommodating section, 75...accommodating rib, 76a...front engaging protrusion, 76b...rear engaging protrusion, 77a...front metal plate, 77b...rear metal plate, 78a...front insulating rib, 78b...rear insulating rib, 81...first transformer, 82...second transformer, 83...third transformer, 84...fourth transformer, 90...CPU, 91...ROM, 92...RAM, 101...first output electrode, 102...second output electrode, 103...third output electrode, 104...fourth output electrode, 200...high voltage power supply board, 810...connecting electrode (first connecting electrode), 820, 830,840...connection electrode, FFC...signal line, P1...transport path, P2...re-transport path, PU...process unit (image forming unit).

Claims

1. an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers for charging the first to fourth photosensitive members, respectively, and for forming an image on a recording medium; a frame on which the image forming unit can be mounted; a substrate disposed at a position facing the image forming unit across the frame; first to fourth output electrodes that are electrically connectable to any of the first to fourth transformers supported by the substrate and output voltages to the first to fourth chargers, respectively; Equipped with The frame is first to fourth housing sections capable of housing the first to fourth transformers, respectively; a cover mounting portion for mounting a cover between the substrate and two or more of the second to fourth housing portions, the cover supporting a relay terminal for electrically connecting two or more of the second to fourth output electrodes and electrically connecting to the fourth transformer, the cover spanning two or more of the second to fourth housing portions and covering at least a part of the housing portions; An image forming apparatus comprising:

2. the relay terminal is electrically connected to the second to fourth output electrodes and to the fourth transformer; 2. The image forming apparatus according to claim 1, wherein the cover extends across the second to fourth storage sections and covers at least a part of the second to fourth storage sections.

3. the first output electrode is electrically connected to the first transformer; the second output electrode is electrically connected to the second transformer; the third output electrode is electrically connected to the third transformer; 3. The image forming apparatus according to claim 1, wherein the fourth output electrode is electrically connected to the fourth transformer.

4. 3. The image forming apparatus according to claim 1, wherein the cover is attached to the cover attachment portion of the frame.

5. the first output electrode is electrically connected to the first transformer; the second to fourth output electrodes are electrically connected to the fourth transformer; 5. The image forming apparatus according to claim 4, wherein the second transformer and the third transformer are not included.

6. 3. The image forming apparatus according to claim 1, wherein the first to fourth storage sections each include a storage rib that surrounds at least a portion of the periphery of the first to fourth transformers that can be stored therein.

7. 7. The image forming apparatus according to claim 6, wherein the relay terminal has a curved portion for climbing over the receiving rib.

8. 8. The image forming apparatus according to claim 7, wherein the cover has a groove for accommodating the curved portion.

9. 3. The image forming apparatus according to claim 1, wherein the cover mounting portion includes an engaging portion that engages with an engaged portion of the cover.

10. 10. The image forming apparatus according to claim 9, wherein the engaged portion includes a plurality of holes, and at least one of the holes is an elongated hole.

11. a duct for allowing air to flow inside the image forming unit; 6. The image forming apparatus according to claim 5, wherein the first and fourth transformers are disposed above the duct.

12. the first transformer has a first connection electrode; 6. The image forming apparatus according to claim 5, wherein the first connection electrode is in direct contact with the first output electrode.

13. a metal plate for positioning the first to fourth photosensitive members; the fourth transformer is disposed between the fourth output electrode and the metal plate; 3. The image forming apparatus according to claim 1, wherein the frame includes an insulating rib between the fourth transformer and the metal plate.

14. a metal plate for positioning the first to fourth photosensitive members; the first transformer is disposed between the first output electrode and the metal plate; 3. The image forming apparatus according to claim 1, wherein the frame includes an insulating rib between the first transformer and the metal plate.

15. an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers for charging the first to fourth photosensitive members, respectively, and for forming an image on a recording medium; a frame on which the image forming unit can be mounted; first to fourth output electrodes that are electrically connectable to any of the first to fourth transformers and output voltages to the first to fourth chargers, respectively; Equipped with The frame is first to fourth housing sections capable of housing the first to fourth transformers, respectively; a mounting portion capable of mounting a support frame that supports a relay terminal that electrically connects two or more of the second to fourth output electrodes and is electrically connected to the fourth transformer; An image forming apparatus comprising:

16. an electrophotographic image forming unit having first to fourth photosensitive members and first to fourth chargers for charging the first to fourth photosensitive members, respectively, and for forming an image on a recording medium; first to fourth output electrodes that are electrically connectable to any of the first to fourth transformers and output voltages to the first to fourth chargers, respectively; An image forming apparatus characterized in that it is possible to change between a first state in which the first to fourth transformers are electrically connected to the first to fourth output electrodes, respectively, and a second state in which only the first transformer and the fourth transformer are provided, the first transformer is electrically connected to the first output electrode, and the fourth transformer is electrically connected to two or more of the second to fourth output electrodes.

Images