Image forming apparatus

Abstract

To provide an image forming apparatus that facilitates replacement of a DC / DC converter and a main motor driving circuit.SOLUTION: An image forming apparatus comprises a body housing, a main motor 160, an AC / DC converter 141, a main substrate 110, and a sub substrate 120. The main substrate 110 has an ASIC 111 that controls the main motor 160. The sub substrate 120 is removably attached to the body housing or the main substrate 110. The sub substrate 120 is electrically connected to both the main motor 160 and the main substrate 110. The sub substrate 120 has a DC / DC converter 121 and a main motor driving circuit 122 arranged thereon. The DC / DC converter 121 converts the DC voltage of a first voltage to the DC voltage of a second voltage lower than the first voltage. The main motor driving circuit 122 outputs driving power to the main motor 160 on the basis of a control signal sent from the ASIC 111.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus having a detachable substrate. [Background technology]

[0002] Conventionally, an image forming apparatus having a detachable board is known (see Patent Document 1). On this board, a DC / DC converter for changing the voltage of a direct current voltage and the like are arranged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-241924 Summary of the Invention [Problem to be solved by the invention]

[0004] In an image forming apparatus, if the main board having the ASIC (main control circuit) also has circuits such as a DC / DC converter and a main motor drive circuit, replacing the DC / DC converter or the main motor drive circuit requires replacing the main board, which is time-consuming.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus in which the DC / DC converter and main motor drive circuit can be easily replaced. [Means for solving the problem]

[0006] In order to achieve the above object, an image forming apparatus according to the present invention includes a main body housing, a photosensitive drum, a main motor, an AC / DC converter, a main board, and a sub-board. The photosensitive drum is rotatable about a rotation axis extending in a first direction. The main motor provides a driving force to the photosensitive drum. The AC / DC converter converts an AC voltage supplied from a commercial power source into a DC voltage of a first voltage. The main board has an ASIC that controls the main motor. The sub-board is detachably attached to at least either the main body housing or the main board. The sub-board is electrically connected to both the main motor and the main board. A DC / DC converter and a main motor drive circuit are arranged on the sub-board. The DC / DC converter converts a first voltage DC to a second voltage DC lower than the first voltage. The main motor drive circuit outputs drive power to the main motor based on a control signal sent from the ASIC.

[0007] When replacing the DC / DC converter or main motor drive circuit, it is only necessary to replace the sub-board, so the DC / DC converter and main motor drive circuit can be easily replaced without replacing the main board containing the ASIC.

[0008] In addition, the sub-board may be disposed between the main motor and the main board in a second direction perpendicular to the up-down direction and the first direction.

[0009] The sub-board may also have a first connector that is disposed parallel to the main board and is directly connected to the main board without a harness.

[0010] Since the sub-board is directly connected to the main board without a harness, the harness can be reduced.

[0011] The sub-board may have at least a portion facing the main board in the first direction, and the first connector may be connected to the main board in the first direction.

[0012] Since the first connector is connected to the main board in the first direction, the sub-board can be easily removed by moving the sub-board in the first direction.

[0013] The first connector may also transmit a DC voltage of the second voltage and a control signal sent from the ASIC.

[0014] The main board can receive the second DC voltage via the sub-board, and can transmit control signals from the ASIC via the sub-board.

[0015] The image forming apparatus may also include a low-voltage power supply board on which an AC / DC converter is arranged, and the low-voltage power supply board and the main board may be electrically connected via a sub-board.

[0016] The low-voltage power supply board and the main board are electrically connected via the sub-board, which allows the number of harnesses to be reduced.

[0017] The image forming apparatus may also include a low-voltage power supply board on which an AC / DC converter is arranged, and a sub-board may include a second connector arranged on which a terminal of a first harness that connects the low-voltage power supply board and the sub-board is connected.

[0018] The main body housing may have a first region on one side of the photosensitive drum in the first direction, and a second region on the other side of the photosensitive drum in the first direction, and the main board, sub-board, and main motor may be located in the first region, and the low-voltage power supply board may be located in the second region.

[0019] Since the main board, sub-board, and main motor are located in the first area and the low-voltage power supply board is located in the second area, interference between the main board, sub-board, and main motor and electromagnetic waves generated from the low-voltage power supply board can be suppressed.

[0020] Furthermore, the sub-board may at least partially overlap the low-voltage power supply board when viewed from the first direction.

[0021] Since the sub-board overlaps the low-voltage power supply board when viewed from the first direction, the first harness can be made shorter than when the sub-board does not overlap the low-voltage power supply board when viewed from the first direction.

[0022] Furthermore, in the vertical direction and in a second direction perpendicular to the first direction, the connection portion between the first harness and the low-voltage power supply board may be located closer to the sub-board than to the main board.

[0023] The connection portion between the first harness and the low-voltage power supply board is located closer to the sub-board than to the main board, so the first harness can be made shorter than if it were located closer to the main board than to the sub-board.

[0024] The sub-board may further include a fuse connected in series with the main motor drive circuit.

[0025] Since the sub-board has a fuse connected in series with the main motor drive circuit, the fuse can be easily replaced by replacing the sub-board.

[0026] The sub-board may further include a fuse connected in series with the DC / DC converter.

[0027] The sub-board is equipped with a fuse connected in series with the DC / DC converter, so the fuse can be easily replaced by replacing the sub-board.

[0028] The exposure unit may further include an exposure unit having a light source device capable of emitting a beam, a polygon mirror that deflects the beam, and a polygon motor that rotates the polygon mirror. The sub-board may further include a polygon motor drive circuit that outputs drive power to the polygon motor. The polygon motor drive circuit may be configured to output drive power to the polygon motor based on a control signal sent from the ASIC.

[0029] When replacing the polygon motor drive circuit, it is only necessary to replace the sub-board, so the polygon motor drive circuit can be easily replaced without replacing the main board having the ASIC.

[0030] The mounting surface of the sub-board may face the direction in which the low-voltage power supply board is located.

[0031] Since the mounting surface of the sub-board faces the direction in which the low-voltage power supply board is located, the first harness can be shortened and the number of times the first harness needs to be bent can be reduced.

[0032] The sheet conveying device may further include a pickup roller that receives driving force from the main motor to feed sheets stored in the sheet tray toward the photosensitive drum, and a gear train that transmits driving force from the main motor to the pickup roller and is located in the first region.The main board, sub-board, main motor, and pickup roller may be arranged in this order in the vertical direction and in a second direction perpendicular to the first direction.

[0033] At least a portion of the sub-board may be located on one side of the rotation axis of the photosensitive drum in a second direction perpendicular to the up-down direction and the first direction, and the first harness may be located on one side of the rotation axis of the photosensitive drum in the second direction.

[0034] Since at least a part of the sub-board and the first harness are located on one side of the rotation axis of the photosensitive drum in the second direction, the first harness can be made short. [Effects of the Invention]

[0035] According to the present invention, it is possible to provide an image forming apparatus in which the DC / DC converter and the main motor drive circuit can be easily replaced. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a main board, a sub-board, a low-voltage power supply board, a high-voltage power supply board, a main motor, etc. [Figure 3] 2 is a block diagram showing electrical connections and control signals for a main board, a sub-board, a low-voltage power supply board, a high-voltage power supply board, a main motor, etc. FIG. [Figure 4] FIG. 2 is a diagram showing the image forming apparatus as viewed from above, illustrating the positional relationship between the main board, sub-board, metal plate, low-voltage power supply board, and main motor. [Figure 5] FIG. 5 is a diagram showing a state in which the sub-board is removed from the state shown in FIG. 4. [Figure 6] FIG. 2 is a diagram showing the image forming apparatus as viewed from a first direction, illustrating the positional relationship between the main board, the sub-board, the metal plate, and the main motor. [Figure 7] FIG. 2 is a diagram of the image forming apparatus as seen from a first direction, showing the positional relationship between a main board, a connector board, a main motor, an electric clutch, and a gear train. [Figure 8] FIG. 11 is a perspective view showing a main board, a sub-board, a low-voltage power supply board, a high-voltage power supply board, a main motor, and the like according to the second embodiment. [Figure 9] FIG. 11 is a block diagram showing electrical connections and control signals for a main board, a sub-board, a low-voltage power supply board, a high-voltage power supply board, a main motor, etc. according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0037] The first embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, image forming apparatus 1 is a monochrome printer. In the following description, the front side (right side in FIG. 1) as viewed from the user using image forming apparatus 1 is referred to as the "front," and the back side (left side in FIG. 1) is referred to as the "rear." The up-down direction is the vertical direction. The front-to-back direction is perpendicular to the up-down direction. Furthermore, the left side (front side of the paper in FIG. 1) as viewed from the user is referred to as the "left," and the right side (back side of the paper in FIG. 1) is referred to as the "left."

[0038] The image forming apparatus 1 includes a main body housing 10, a front cover 20, a sheet supply unit 30, an image forming unit 40, a discharge roller 81, and an operation panel 180.

[0039] The main body housing 10 is a housing that houses the sheet supply unit 30, the image forming unit 40, and the like. The front cover 20 opens and closes the front opening 11 of the main body housing 10. The front opening 11 is formed in the front surface of the main body housing 10.

[0040] Operation panel 180 is disposed on top surface 10A of main body housing 10. Operation panel 180 is capable of displaying various messages and inputting commands to image forming apparatus 1. Operation panel 180 is disposed on the front side of main body housing 10.

[0041] The sheet supply unit 30 supplies sheets S to the image forming unit 40. The sheet supply unit 30 is located at the bottom inside the main body housing 10. The sheet supply unit 30 includes a sheet tray 31 and a sheet supply mechanism 32. The sheet tray 31 stores sheets S to be supplied to the image forming unit 40. The sheet tray 31 is detachable from the main body housing 10. The sheet tray 31 can be removed by pulling it forward from the main body housing 10. When attached to the main body housing 10, the sheet tray 31 is located below the image forming unit 40.

[0042] The sheet supply mechanism 32 includes a pickup roller 33, a separation roller 34, a separation pad 35, a first roller 36, and a registration roller 37. The pickup roller 33 feeds the sheets S stored in the sheet tray 31 toward the photosensitive drum 61. The separation roller 34 and the separation pad 35 separate the sheets S fed by the pickup roller 33 into a single sheet. The first roller 36 and the registration roller 37 transport the sheets S toward the image forming unit 40.

[0043] The image forming section 40 forms an image on the sheet S. The image forming section 40 includes an exposure unit 50, a process unit 60, and a fixing unit .

[0044] The exposure unit 50 is located in the upper part of the main body housing 10. The exposure unit 50 has an optical device 51, a polygon mirror 52, and a polygon motor 53. The optical device 51 emits a laser beam as an example of a beam. The polygon mirror 52 deflects the laser beam emitted from the optical device 51. The polygon motor 53 rotates the polygon mirror 52. As shown by the imaginary lines, the exposure unit 50 emits a light beam from the optical device 51, which is deflected by the polygon mirror 52 and then exposes the surface of a photosensitive drum 61 of the image forming section 40.

[0045] The process unit 60 is located between the exposure unit 50 and the sheet tray 31 inside the main body housing 10. When removing the process unit 60, the process unit 60 is pulled forward from the main body housing 10 with the front cover 20 open. The developing unit 60B is detachable from the drum unit 60A when the process unit 60 is removed from the main body housing 10. The process unit 60 includes the drum unit 60A and the developing unit 60B, which is detachable from the drum unit 60A.

[0046] The process unit 60 can be attached to and detached from the main body casing 10 through the front opening 11 when the front cover 20 is open. The drum unit 60A includes a photosensitive drum 61, a uniform positive charger 62, and a transfer roller 63.

[0047] The photosensitive drum 61 is rotatable about a rotation axis 61X extending in the first direction. A toner image is formed on the surface of the photosensitive drum 61. The charger 62 charges the photosensitive drum 61. The transfer roller 63 transfers the toner image onto the sheet S together with the photosensitive drum 61.

[0048] In the following description, the direction in which the rotation axis 61X of the photosensitive drum 61 extends is referred to as the "first direction." Furthermore, the direction perpendicular to the up-down direction and the first direction is referred to as the "second direction." Furthermore, the arrow directions in the drawings point to one side of each direction. Furthermore, the direction opposite to one side is referred to as the other side. In this embodiment, the first direction is the left-right direction, and one side of the first direction is the left side, and the other side of the second direction is the right side. The second direction is the front-rear direction. In this embodiment, one side of the second direction is the rear side, and the other side of the second direction is the front side.

[0049] The developing unit 60B has a developing roller 64, a supply roller 65, a layer thickness regulating blade 66, an agitator 67, and a toner storage section 68. The toner storage section 68 stores toner. The agitator 67 agitates the toner in the toner storage section 68. The agitator 67 also supplies toner to the supply roller 65. The supply roller 65 supplies toner to the developing roller 64. The layer thickness regulating blade 66 contacts the surface of the developing roller 64 and regulates the thickness of the toner on the developing roller 64 to a constant thickness.

[0050] The fixing unit 70 is located behind the process unit 60 inside the main body housing 10. The fixing unit 70 includes a heating unit 71 and a pressure roller 72. The heating unit 71 heats the sheet S. The pressure roller 72 is pressed against the heating unit 71.

[0051] In the image forming section 40, the exposure unit 50 emits a light beam onto the surface of the charged photosensitive drum 61. As a result, an electrostatic latent image based on image data is formed on the photosensitive drum 61. The development roller 64 supplies toner to the surface of the exposed photosensitive drum 61. As a result, a toner image is formed on the photosensitive drum 61.

[0052] The photosensitive drum 61 and the transfer roller 63 transport the sheet S supplied from the sheet supply unit 30. As a result, the toner image formed on the photosensitive drum 61 is transferred onto the sheet S. The heating unit 71 and the pressure roller 72 transport the sheet S onto which the toner image has been transferred. As a result, the toner image transferred onto the sheet S is fixed onto the sheet S.

[0053] The discharge rollers 81 are located above the fixing unit 70. The discharge rollers 81 discharge the sheet S, on which an image has been formed by the image forming section 40, onto the discharge tray 13. The discharge tray 13 is formed on the top surface 10A of the main body housing 10.

[0054] As shown in FIG. 2, the image forming apparatus 1 includes a main board 110, a sub-board 120, a low-voltage power supply board 140, a high-voltage power supply board 150, and a main motor 160.

[0055] The main board 110 and the sub-board 120 are connected directly without a harness. The sub-board 120 and the low-voltage power supply board 140 are connected by a first harness H1. The sub-board 120 and the main motor 160 are connected by a second harness H2. The sub-board 120 and the high-voltage power supply board 150 are connected by a third harness H3. The sub-board 120 and the operation panel 180 are connected by a fourth harness H4. The sub-board 120 and the circuit board 50A of the optical device 51 are connected by a fifth harness H5. The sub-board 120 and the polygon motor 53 are connected by a sixth harness H6.

[0056] The type of harness is optional, and the harness may be an FFC (flexible flat cable).

[0057] As shown in FIG. 3, the main board 110 includes an ASIC 111, a sub-converter 112, a ROM 114, a RAM 115, a non-volatile memory 116, a USB connector 118, a LAN connector 119, and a main connector CM.

[0058] The ROM 114 stores a control program, setting data, and the like for controlling the image forming apparatus 1. The RAM 115 and the non-volatile memory 116 are used as a working area from which the control program is read and as a storage area for temporarily storing image data included in a print job.

[0059] The ASIC 111 is a semiconductor integrated circuit for executing print control of the image forming apparatus 1. The ASIC 111 is a control device that executes print control by performing arithmetic processing based on control programs and data stored in the ROM 114, the RAM 115, and the nonvolatile memory 116. In this embodiment, the ASIC 111 controls the operation panel 180, the exposure unit 50, and the main motor 160.

[0060] The sub-converter 112 converts the second DC voltage into a third DC voltage that is lower than the second voltage. The second voltage is, for example, 5 V or 3.3 V. The third voltage is, for example, 1.1 V.

[0061] The USB connector 118 and the LAN connector 119 are arranged at one end of the main board 110 in the second direction. The USB connector 118 and the LAN connector 119 are exposed to the outside of the main body housing 10 from one side (rear side) of the main body housing 10 in the second direction.

[0062] The USB connector 118 is a connector to which a USB terminal of an external device such as a PC is connected. When the USB terminal of the external device is connected to the USB connector 118, the ASIC 111 becomes able to send and receive data to and from the external device.

[0063] A LAN cable is connected to the LAN connector 119. When a LAN cable is connected to the LAN connector 119, the ASIC 111 can send and receive data to and from external devices.

[0064] The main connector CM is a connector that is connected to the sub-board 120. The main connector CM is connected to the sub-board 120.

[0065] The sub-board 120 is electrically connected to both the main motor 160 and the main board 110. The sub-board 120 does not include a control device or main control circuit, such as an ASIC or CPU. The sub-board 120 includes a DC / DC converter 121, a main motor drive circuit 122, a polygon motor drive circuit 123, a first connector C1, a second connector C2, a third connector C3, a fourth connector C4, a fifth connector C5, a sixth connector C6, a seventh connector C7, a first fuse F1, a second fuse F2, a third fuse F3, and a fourth fuse F4. The first fuse F1, the second fuse F2, the third fuse F3, and the fourth fuse F4 are examples of fuses. Note that FIG. 3 is a block diagram showing the electrical connections of each board, and therefore the positions of the connectors differ from those in FIGS. 2 and 4.

[0066] The DC / DC converter 121 converts a first voltage DC to a second voltage DC that is lower than the first voltage. The first voltage is, for example, 24V. The second voltage is, for example, 3.3V.

[0067] The first fuse F1 is connected in series with the DC / DC converter 121. In this embodiment, the first fuse F1 is arranged on the primary side of the DC / DC converter 121. When an excessive current flows through the first fuse F1, the first fuse F1 melts and cuts off the current flowing through the DC / DC converter 121.

[0068] The main motor drive circuit 122 is a circuit that drives and controls the main motor 160. Specifically, the main motor drive circuit 122 is supplied with a first DC voltage from the low-voltage power supply board 140. The main motor drive circuit 122 outputs drive power to the main motor 160 based on a control signal sent from the ASIC 111.

[0069] The second fuse F2 is connected in series with the main motor drive circuit 122. In this embodiment, the second fuse F2 is arranged on the primary side of the main motor drive circuit 122. When an excessive current flows through the second fuse F2, the second fuse F2 melts and cuts off the current flowing through the main motor drive circuit 122.

[0070] The polygon motor drive circuit 123 is a circuit that drives and controls the polygon motor 53. Specifically, the polygon motor drive circuit 123 is supplied with a first DC voltage from the low-voltage power supply board 140. The polygon motor drive circuit 123 outputs drive power to the polygon motor 53 based on a control signal sent from the ASIC 111.

[0071] The third fuse F3 is connected in series with the polygon motor drive circuit 123. In this embodiment, the third fuse F3 is arranged on the primary side of the polygon motor drive circuit 123. When an excessive current flows through the third fuse F3, the third fuse F3 melts and cuts off the current flowing through the polygon motor drive circuit 123.

[0072] The first connector C1 is a connector for connecting the sub-board 120 to the main board 110. The first connector C1 and the main connector CM are board-to-board connectors for connecting boards together. At least one of the first connector C1 and the main connector CM may be a floating connector designed to absorb positional errors by moving relative to the main board 110 and the connector board 120.

[0073] The second connector C2 is a connector for connecting the low-voltage power supply board 140 to the sub-board 120. A terminal of the first harness H1 is connected to the second connector C2.

[0074] The third connector C3 is a connector for connecting the main motor 160 to the sub-board 120. A terminal of the second harness H2 is connected to the third connector C3.

[0075] The fourth connector C4 is a connector for connecting the high-voltage power supply board 150 to the sub-board 120. A terminal of the third harness H3 is connected to the fourth connector C4.

[0076] The fifth connector C5 is a connector for connecting the operation panel 180 to the sub-board 120. A terminal of the fourth harness H4 is connected to the fifth connector C5.

[0077] The sixth connector C6 is a connector for connecting the circuit board 50A of the optical device 51 to the sub-board 120. A terminal of the fifth harness H5 is connected to the sixth connector C6.

[0078] The seventh connector C7 is a connector for connecting the polygon motor 53 to the sub-board 120. A terminal of the sixth harness H6 is connected to the seventh connector C7.

[0079] The low-voltage power supply board 140 has an AC / DC converter 141 and a connection section 142. The AC / DC converter 141 is a converter that converts AC voltage supplied from a commercial power source into DC voltage of a first voltage. The connection section 142 is a section that connects the first harness H1 to the low-voltage power supply board 140. In this embodiment, the low-voltage power supply board 140 and the main board 110 are electrically connected via the sub-board 120. In other words, the low-voltage power supply board 140 and the main board 110 are not connected by a harness.

[0080] The low-voltage power supply board 140 is covered by a box-shaped metal enclosure (not shown) and is housed in the main body housing 10 in a detachable manner.

[0081] The high-voltage power supply board 150 is detachably housed in the main body housing 10. The high-voltage power supply board 150 has a circuit that generates a high voltage by boosting the first voltage supplied from the low-voltage power supply board 140. The high-voltage power supply board 150 has a charging voltage application circuit 151, a development voltage application circuit 152, and a transfer voltage application circuit 153.

[0082] The charging voltage application circuit 151 is a circuit that applies a charging voltage of positive polarity to the charger 62. The charging voltage is, for example, 5 kV to 8 kV. The developing voltage application circuit 152 is a circuit that applies a developing voltage of positive polarity to the developing roller 64. The developing voltage is, for example, 300V to 500V. The transfer voltage application circuit 153 is a circuit that applies a transfer voltage to the transfer roller 63. The transfer voltage application circuit 153 controls the transfer voltage so that the current flowing through the transfer roller 63 has a predetermined current value. The transfer voltage is, for example, about minus several thousand volts.

[0083] The fourth fuse F4 is disposed between the low-voltage power supply board 140 and the high-voltage power supply board 150 and is connected in series with the high-voltage power supply board 150. That is, the fourth fuse F4 is connected in series with the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153. In this embodiment, the fourth fuse F4 is disposed on the primary side of the high-voltage power supply board 150. That is, the fourth fuse F4 is disposed on the primary side of the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153. When an excessive current flows through the fourth fuse F4, the fourth fuse F4 melts and cuts off the current flowing from the low-voltage power supply board 140 to the high-voltage power supply board 150, i.e., the current flowing through the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153.

[0084] The main motor 160 provides driving force to the pickup roller 33, the separation roller 34, the first roller 36, the registration roller 37, the photosensitive drum 61, the developing roller 64, the supply roller 65, the agitator 67, the pressure roller 72, and the discharge roller 81. The pickup roller 33, the separation roller 34, the first roller 36, the registration roller 37, the photosensitive drum 61, the pressure roller 72, and the discharge roller 81 receive driving force from the main motor 160 to transport the sheet S.

[0085] Operation panel 180 has operation panel ASIC 181 and LCD 182. Operation panel ASIC 181 is a semiconductor integrated circuit for executing operations on operation panel 180. LCD 182 is a display into which commands can be input. Various messages are displayed on LCD 182 in accordance with operation panel ASIC 181. In this embodiment, a direct current of a first voltage is sent to LCD 182 via sub-substrate 120, not via main substrate 110.

[0086] As shown in Fig. 4, the main board 110 is fixed to the main body housing 10. The main board 110 is fixed to a first metal plate 10F with screws N (see also Fig. 6). The main board 110 is detachable from the main body housing 10. The first metal plate 10F is fixed to the main body housing 10. The first metal plate 10F is a metal plate and extends in a direction perpendicular to the first direction.

[0087] The mounting surface of the main board 110 faces the first direction. That is, the ASIC 111 is disposed on the board mounting surface facing the first direction. In this embodiment, the mounting surface of the main board 110 faces one side of the first direction, i.e., the left. The main connector CM faces one side of the first direction, i.e., the left. The main connector CM is connected to the first connector C1 of the sub-board 120.

[0088] The sub-board 120 is detachably fixed to the main housing 10. The sub-board 120 is arranged parallel to the main board 110. At least a portion of the sub-board 120 faces the main board 110 in the first direction. The main board 110 is directly connected to the first connector C1 without a harness. In this embodiment, the first connector C1 faces the main connector CM in the first direction, and they face each other. That is, the first connector C1 is connected to the main board 110 in the first direction.

[0089] The main connector CM and the first connector C1 are board-to-board connectors for connecting the boards together. At least one of the main connector CM and the first connector C1 may be a floating connector designed to absorb positional errors by moving relative to the main board 110 and the sub-board 120.

[0090] The main connector CM supports the sub-board 120 via the first connector C1. Therefore, the main board 110 supports the rear end of the sub-board 120. In addition, the first metal plate 10F supports the sub-board 120 via the main board 110.

[0091] At least a portion of the sub-substrate 120 is located on one side in the second direction of the rotation axis 61X of the photosensitive drum 61. The first harness H1 is located on one side in the second direction of the rotation axis 61X of the photosensitive drum 61. In this embodiment, the entire sub-substrate 120 is located on one side in the second direction of the rotation axis 61X of the photosensitive drum 61.

[0092] In the second direction, the connection portion 142 between the first harness H1 and the low-voltage power supply board 140 is disposed at a position closer to the sub-board 120 than to the main board 110.

[0093] The image forming apparatus 1 further includes a second metal plate 130, an electric clutch 170, and a gear train 190.

[0094] The second metal plate 130 is fixed to the main housing 10. The second metal plate 130 is a metal plate and extends in a direction perpendicular to the first direction. The second metal plate 130 supports the main motor 160. The sub-board 120 is detachably supported by the second metal plate 130.

[0095] In the first direction, the second metal plate 130 is located between the main board 110 and the sub-board 120. The main board 110 and the second metal plate 130 are located at different positions in the second direction. Specifically, the second metal plate 130 is located in front of the main board 110.

[0096] The second metal sheet 130 is disposed on one side of the first metal sheet 10F in the first direction. The second metal sheet 130 is located in front of the first metal sheet 10F. The rear end of the metal sheet 130 is located in front of the front end of the main board 110. In this embodiment, the second metal sheet 130 is electrically connected to the first metal sheet 10F by a ground wire (not shown).

[0097] The second metal sheet 130 has a protrusion 131 that protrudes toward the sub-substrate 120. The sub-substrate 120 is fixed to the protrusion 131 with a screw N. The protrusion 131 protrudes to one side in the first direction when the sub-substrate 120 is fixed to the second metal sheet 130. When the sub-substrate 120 is fixed to the second metal sheet 130, the protrusion 131 serves as a spacer that ensures a distance between the sub-substrate 120 and the portion of the second metal sheet 130 other than the protrusion 131. The protrusion 131 is formed by bending the metal sheet 130. The protrusion 131 has an attachment surface 131M for attaching the screw N (see FIG. 5). The attachment surface 131M extends in a direction perpendicular to the first direction.

[0098] The electric clutch 170 is switchable between a transmission state in which the driving force from the main motor 160 is transmitted to the pickup roller 33 and a disconnection state in which the driving force from the main motor 160 is not transmitted to the pickup roller 33 .

[0099] The gear train 190 is made up of multiple gears and is in mesh with a motor gear MG provided on the output shaft of the main motor 160 and the electric clutch 170. The gear train 190 receives driving force from the main motor 160 and transmits the driving force to the pickup roller 33 via the electric clutch 170.

[0100] The electric clutch 170 and the gear train 190 are located on the other side of the main motor 160 in the second direction. In the second direction, the main board 110, the sub-board 120, the main motor 160, and the pickup roller 33 are arranged in this order. In the second direction, the sub-board 120 is disposed between the main motor 160 and the main board 110.

[0101] Here, the main body housing 10 has a first region RE1 and a second region RE2. The first region RE1 is outside the photosensitive drum 61 in the first direction and is a region on one side of the photosensitive drum 61 in the first direction. The second region RE2 is outside the photosensitive drum 61 in the first direction and is a region on the other side of the photosensitive drum 61 in the first direction.

[0102] The main board 110, the sub-board 120, the second sheet metal 130, the main motor 160, the electric clutch 170, and the gear train 190 are all arranged in the first region RE1. The low-voltage power supply board 140 and the high-voltage power supply board 150 are arranged in the second region RE2.

[0103] Also, the main body housing 10 has a first end 1E and a second end 2E. The first end 1E is the left end of the main body housing 10, that is, the end of the main body housing 10 close to the first region RE1 in the first direction. The second end 2E is the right end of the main body housing 10, that is, the end of the main body housing 10 farther from the first region RE1 than the first end 1E in the first direction.

[0104] The distance D1 between the sub-board 120 and the first end 1E is smaller than the distance D2 between the main board 110 and the first end 1E (D1 < D2). Also, the distance D1 between the sub-board 120 and the first end 1E is smaller than the distance D3 between the second sheet metal 130 and the first end 1E (D1 < D3). In this embodiment, the distance D3 between the second sheet metal 130 and the first end 1E is smaller than the distance D2 between the main board 110 and the first end 1E (D3 < D2). Thus, in this embodiment, among the main board 110, the sub-board 120, and the second sheet metal 130, the sub-board 120 is located on the outermost side of the first region RE1, and the main board 110 is located on the innermost side.

[0105] Here, the main board 110 has a mounting surface 110A. An ASIC 111 and a main connector CM are arranged on the mounting surface 110A of the main board 110.

[0106] The sub-substrate 120 also has a mounting surface 120A. A DC / DC converter 121, a main motor drive circuit 122, and a polygon motor drive circuit 123 are arranged on the mounting surface 120A of the sub-substrate 120. A first connector C1, a second connector C2, a third connector C3, a fourth connector C4, a fifth connector C5, and a sixth connector C6 are also arranged on the mounting surface 120A of the sub-substrate 120 (see FIG. 2).

[0107] The mounting surface 110A of the main board 110 faces in the first direction. The mounting surface 120A of the sub-board 120 faces in the first direction. In this embodiment, the mounting surface 110A of the main board 110 faces one side in the first direction, i.e., the left. The ASIC 111 is arranged on the surface of the main board 110 facing the first end 1E. The mounting surface 120A of the sub-board 120 faces the other side in the first direction, i.e., the right. The mounting surface 120A of the sub-board 120 faces in the direction in which the low-voltage power supply board 140 is located. The DC / DC converter 121 is arranged on the surface of the sub-board 120 facing the second end 2E.

[0108] The first harness H1 extends from the first region RE1 to the second region RE2 along the first direction. Specifically, the first harness H1 extends from the first region RE1 to the second region RE2, passing through a region on one side of the rotation axis 61X of the photosensitive drum 61 in the second direction.

[0109] The main board 110 and the sub-board 120 are located in an area on one side of the rotation axis 61X of the photosensitive drum 61 in the second direction.

[0110] As shown in FIGS. 4 and 5, the sub-substrate 120 is detachable from the main body housing 10. To this end, the main body housing 10 has a second opening 12 and a side cover 12A on one side in the first direction. The second opening 12 is an opening formed in the first region RE1. The second opening 12 is an opening for attaching and detaching the sub-substrate 120. The side cover 12A is detachable from the main body housing 10, and covers the second opening 12 when attached. Furthermore, when the side cover 12A is removed, the second opening 12 is opened, and the sub-substrate 120 can be attached and detached through the second opening 12.

[0111] When removing the sub-board 120 from the main body housing 10, the side cover 12A is removed from the state shown in FIG. 4 to the state shown in FIG. 5. When the side cover 12A is removed, the second opening 12 is opened. With the second opening 12 opened, the user removes the corresponding harness terminals from the second connector C2, the third connector C3, the fourth connector C4, the fifth connector C5, and the sixth connector C6. Then, the user removes the screws N located at the front of the sub-board 120.

[0112] After removing each connector and screw N, the user pulls the sub-board 120 to one side in the first direction, for example, to the left. Pulling the sub-board 120 to one side in the first direction disconnects the first connector C1 of the sub-board 120 from the main connector CM of the main board 110, and the sub-board 120 can be pulled out to one side in the first direction, for example, to the left.

[0113] When attaching the sub-board 120 to the main housing 10, the side cover 12A is removed and the sub-board 120 is inserted into the second opening 12. Then, the first connector C1 of the sub-board 120 is faced to the main connector CM of the main board 110 and pushed in. This connects the first connector C1 to the main connector CM, allowing the rear part of the sub-board 120 to be attached to the main board 110. In this state, the front part of the sub-board 120 is fixed to the second metal plate 130 with screws N. This fixes the front and rear parts of the sub-board 120 to the main housing 10.

[0114] Once the sub-board 120 is fixed to the main body housing 10, the terminals of the harnesses corresponding to the second connector C2, the third connector C3, the fourth connector C4, the fifth connector C5, and the sixth connector C6 are connected. After each connector is connected, the side cover 12A is attached to the main body housing 10. In this way, the sub-board 120 can be easily attached to and detached from the main board 110 from one side in the first direction.

[0115] 6, when viewed from the first direction, the sub-substrate 120 at least partially overlaps with the low-voltage power supply substrate 140. In this embodiment, when viewed from the first direction, the upper part of the sub-substrate 120 does not overlap with the low-voltage power supply substrate 140, and the lower part overlaps with the low-voltage power supply substrate 140.

[0116] The first connector C1 is disposed at one end of the sub-board 120 in the second direction. The rear end of the sub-board 120 is fixed by the first connector C1. The sub-board 120 is supported detachably with respect to the main connector CM.

[0117] Here, the transmission path of the power supplied from the low-voltage power supply board 140 and the transmission path of the control signal sent from the ASIC 111 will be described.

[0118] 3, DC / DC converter 121 is supplied with a DC voltage of a first voltage from AC / DC converter 141 via second connector C2 and first fuse F1. As described above, DC / DC converter 121 converts the DC voltage of the first voltage into a DC voltage of a second voltage that is lower than the first voltage.

[0119] The ASIC 111 is supplied with power from the low-voltage power supply board 140 via the DC / DC converter 121 and the sub-converter 112. More specifically, the sub-converter 112 is supplied with a direct current voltage converted to a second voltage by the DC / DC converter 121 via the first connector C1. The ASIC 111 is supplied with a direct current voltage converted to a third voltage by the sub-converter 112. The amount of power supplied from the low-voltage power supply board 140 to the DC / DC converter 121 and the like is adjusted based on a control signal sent from the ASIC 111.

[0120] The main motor drive circuit 122 is supplied with a DC voltage of the first voltage from the AC / DC converter 141 via the second connector C2 and the second fuse F2. Based on a control signal sent from the ASIC 111, the main motor drive circuit 122 converts the DC voltage of the first voltage into a drive voltage for the main motor 160 and outputs it to the main motor 160 via the third connector C3. The ASIC 111 sends a control signal to the main motor 160 via the first connector C1 and the third connector C3. The ASIC 111 also receives a signal from the main motor 160 via the third connector C3 and the first connector C1.

[0121] The polygon motor drive circuit 123 is supplied with a first DC voltage from the AC / DC converter 141 via the second connector C2 and the third fuse F3. Based on a control signal sent from the ASIC 111, the polygon motor drive circuit 123 converts the first DC voltage into a drive voltage for the polygon motor 53 and outputs it to the polygon motor 53 via the sixth connector C6. The ASIC 111 sends a control signal to the polygon motor 53 via the first connector C1 and the seventh connector C7. The ASIC 111 also receives a signal from the polygon motor 53 via the seventh connector C7 and the first connector C1.

[0122] The charging voltage application circuit 151 receives power from the low-voltage power supply board 140 via the sub-board 120, without passing through the main board 110. More specifically, the charging voltage application circuit 151 receives a first DC voltage from the AC / DC converter 141 via the second connector C2, the fourth fuse F4, and the fourth connector C4. The charging voltage application circuit 151 outputs a charging voltage to the charger 62 based on a control signal sent from the ASIC 111 via the first connector C1 and the fourth connector C4.

[0123] The developing voltage application circuit 152 receives power from the low-voltage power supply board 140 via the sub-board 120, without passing through the main board 110. More specifically, the developing voltage application circuit 152 receives a first DC voltage from the AC / DC converter 141 via the second connector C2, the fourth fuse F4, and the fourth connector C4. The developing voltage application circuit 152 outputs a developing voltage to the developing roller 64 based on a control signal sent from the ASIC 111 via the first connector C1 and the fourth connector C4.

[0124] The transfer voltage application circuit 153 receives power from the low-voltage power supply board 140 via the sub-board 120, without passing through the main board 110. More specifically, the transfer voltage application circuit 153 receives a first DC voltage from the AC / DC converter 141 via the second connector C2, the fourth fuse F4, and the fourth connector C4. The transfer voltage application circuit 153 outputs a transfer voltage to the transfer roller 63 based on a control signal sent from the ASIC 111 via the first connector C1 and the fourth connector C4.

[0125] The ASIC 111 transmits a control signal to the optical device 51 via the sub-board 120 to control the emission of laser light from the optical device 51. More specifically, the ASIC 111 transmits a control signal to the optical device 51 via the first connector C1 and the sixth connector C6.

[0126] ASIC 111 can receive commands input to operation panel 180 via sub-board 120 and can also send messages to operation panel 180. Specifically, ASIC 111 receives commands input from operation panel ASIC 181 via fifth connector C5 and first connector C1. ASIC 111 also sends messages to operation panel ASIC 181 via first connector C1 and fifth connector C5.

[0127] The LCD 182 is supplied with a DC voltage of the first voltage from the AC / DC converter 141 via the second connector C2 and the fifth connector C5.

[0128] As described above, the first connector C1 transmits the DC voltage of the second voltage and the control signal sent from the ASIC 111. The fifth connector C5 transmits the DC voltage of the second voltage and the control signal sent from the ASIC 111. The sixth connector C6 transmits the drive power for the polygon motor 53 and the control signal sent from the ASIC 111.

[0129] As described above, the following effects can be obtained in this embodiment. In the image forming apparatus 1, the sub-board 120 does not have the ASIC 111, but has a DC / DC converter 121 and a main motor drive circuit 122 arranged thereon. Therefore, when replacing the DC / DC converter 121 or the main motor drive circuit 122, it is sufficient to replace the sub-board 120. In other words, the DC / DC converter 121 and the main motor drive circuit 122 can be easily replaced without replacing the main board 110 that has the ASIC 111.

[0130] Furthermore, since the sub-board 120 is directly connected to the main board 110 without a harness, the number of harnesses can be reduced.

[0131] Furthermore, the first connector C1 of the sub-board 120 is connected in a first direction to the main board 110. Therefore, the sub-board 120 can be easily removed by moving the sub-board 120 in the first direction.

[0132] Furthermore, the first connector C1 of the sub-board 120 transmits the DC voltage of the second voltage and a control signal sent from the ASIC 111. Therefore, the main board 110 can receive the DC voltage of the second voltage via the sub-board 120, and can transmit a control signal from the ASIC 111 via the sub-board 120.

[0133] Furthermore, the low-voltage power supply board 140 and the main board 110 are electrically connected via the sub-board 120. Therefore, by not providing a harness that connects the low-voltage power supply board 140 and the main board 110, the number of harnesses can be reduced.

[0134] Furthermore, the main board 110, the sub-board 120, and the main motor 160 are located in the first region RE1, and the low-voltage power supply board 140 is located in the second region RE2. This prevents the main board 110, the sub-board 120, and the main motor 160 from being interfered with by electromagnetic waves generated from the low-voltage power supply board 140.

[0135] Furthermore, when viewed from the first direction, the sub-board 120 at least partially overlaps with the low-voltage power supply board 140. Therefore, the first harness H1 can be made shorter than when the sub-board 120 does not overlap with the low-voltage power supply board 140 when viewed from the first direction.

[0136] Furthermore, the connection portion between the first harness H1 and the low-voltage power supply board 140 is located closer to the sub-board 120 than to the main board 110. Therefore, the first harness H1 can be made shorter than when it is located closer to the main board 110 than to the sub-board 120.

[0137] Furthermore, the connection portion between the first harness H1 and the low-voltage power supply board 140 is located closer to the sub-board 120 than to the main board 110. Therefore, the first harness H1 can be made shorter than when it is located closer to the main board 110 than to the sub-board 120.

[0138] The sub-board 120 also includes a second fuse F2 connected in series with the main motor drive circuit 122. Therefore, by replacing the sub-board 120, the second fuse F2 can be easily replaced.

[0139] The sub-board 120 also includes a first fuse F1 connected in series with the DC / DC converter 121. Therefore, by replacing the sub-board 120, the first fuse F1 can be easily replaced.

[0140] Furthermore, when replacing the polygon motor drive circuit 123, it is sufficient to replace the sub-board 120. Therefore, the polygon motor drive circuit 123 can be easily replaced without replacing the main board 110 having the ASIC 111.

[0141] Furthermore, the mounting surface 120A of the sub-board 120 faces the direction in which the low-voltage power supply board 140 is located. This shortens the first harness H1 and reduces the number of times the first harness H1 needs to be bent.

[0142] Furthermore, at least a part of the sub-board 120 and the first harness H1 are located on one side in the second direction of the rotation axis 61X of the photosensitive drum 61. This allows the first harness H1 to be shortened.

[0143] Next, a second embodiment will be described.

[0144] The second embodiment differs from the first embodiment in that the high-voltage power supply board 150, the operation panel 180, and the circuit board 50A of the optical device 51 are connected to the main board 110 without going through the sub-board 120.

[0145] 8 and 9, the main board 110 of the second embodiment has an ASIC 111, a sub-converter 112, a ROM 114, a RAM 115, a non-volatile memory 116, a USB connector 118, a LAN connector 119, a main connector CM, a fourth connector C4, a fifth connector C5, and a sixth connector C6. Note that, since FIG. 9 is a block diagram showing the electrical connections of each board, the positions of each connector differ from those in FIG. 8.

[0146] The ROM 114 stores a control program, setting data, and the like for controlling the image forming apparatus 1. The RAM 115 and the non-volatile memory 116 are used as a working area from which the control program is read and as a storage area for temporarily storing image data included in a print job.

[0147] The ASIC 111 is a semiconductor integrated circuit for executing print control of the image forming apparatus 1. The ASIC 111 is a control device that executes print control by performing arithmetic processing based on control programs and data stored in the ROM 114, the RAM 115, and the nonvolatile memory 116. In this embodiment, the ASIC 111 controls the operation panel 180, the exposure unit 50, and the main motor 160.

[0148] The sub-converter 112 converts the second DC voltage into a third DC voltage that is lower than the second voltage. The second voltage is, for example, 5 V or 3.3 V. The third voltage is, for example, 1.1 V.

[0149] The USB connector 118 and the LAN connector 119 are arranged at one end of the main board 110 in the second direction. The USB connector 118 and the LAN connector 119 are exposed to the outside of the main body housing 10 from one side (rear side) of the main body housing 10 in the second direction.

[0150] The USB connector 118 is a connector to which a USB terminal of an external device such as a PC is connected. When the USB terminal of the external device is connected to the USB connector 118, the ASIC 111 becomes able to send and receive data to and from the external device.

[0151] A LAN cable is connected to the LAN connector 119. When a LAN cable is connected to the LAN connector 119, the ASIC 111 can send and receive data to and from external devices.

[0152] The main connector CM is a connector that is connected to the sub-board 120. The main connector CM is connected to the sub-board 120.

[0153] The fourth connector C4 is a connector for connecting the high-voltage power supply board 150 to the main board 110. A terminal of the third harness H3 is connected to the fourth connector C4.

[0154] The fifth connector C5 is a connector for connecting the operation panel 180 to the main board 110. A terminal of the fourth harness H4 is connected to the fifth connector C5.

[0155] The sixth connector C6 is a connector for connecting the circuit board 50A of the optical device 51 to the main board 110. A terminal of the fifth harness H5 is connected to the sixth connector C6.

[0156] The sub-board 120 of the second embodiment includes a DC / DC converter 121, a main motor drive circuit 122, a polygon motor drive circuit 123, a first connector C1, a second connector C2, a third connector C3, a seventh connector C7, a first fuse F1, a second fuse F2, a third fuse F3, and a fifth fuse F5. The first fuse F1, the second fuse F2, the third fuse F3, and the fifth fuse F5 are examples of fuses.

[0157] The DC / DC converter 121 converts a first voltage DC to a second voltage DC that is lower than the first voltage. The first voltage is, for example, 24V. The second voltage is, for example, 3.3V.

[0158] The first fuse F1 is connected in series with the DC / DC converter 121. In this embodiment, the first fuse F1 is arranged on the primary side of the DC / DC converter 121. When an excessive current flows through the first fuse F1, the first fuse F1 melts and cuts off the current flowing through the DC / DC converter 121.

[0159] The main motor drive circuit 122 is a circuit that drives and controls the main motor 160. Specifically, the main motor drive circuit 122 is supplied with a first DC voltage from the low-voltage power supply board 140. The main motor drive circuit 122 outputs drive power to the main motor 160 based on a control signal sent from the ASIC 111.

[0160] The second fuse F2 is connected in series with the main motor drive circuit 122. In this embodiment, the second fuse F2 is arranged on the primary side of the main motor drive circuit 122. When an excessive current flows through the second fuse F2, the second fuse F2 melts and cuts off the current flowing through the main motor drive circuit 122.

[0161] The polygon motor drive circuit 123 is a circuit that drives and controls the polygon motor 53. Specifically, the polygon motor drive circuit 123 is supplied with a first DC voltage from the low-voltage power supply board 140. The polygon motor drive circuit 123 outputs drive power to the polygon motor 53 based on a control signal sent from the ASIC 111.

[0162] The third fuse F3 is connected in series with the polygon motor drive circuit 123. In this embodiment, the third fuse F3 is arranged on the primary side of the polygon motor drive circuit 123. When an excessive current flows through the third fuse F3, the third fuse F3 melts and cuts off the current flowing through the polygon motor drive circuit 123.

[0163] The fifth fuse F5 is disposed between the low-voltage power supply board 140 and the high-voltage power supply board 150 and is connected in series with the high-voltage power supply board 150. That is, the fifth fuse F5 is connected in series with the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153. In this embodiment, the fifth fuse F5 is disposed on the primary side of the high-voltage power supply board 150. That is, the fifth fuse F5 is disposed on the primary side of the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153. When an excessive current flows through the fifth fuse F5, the fifth fuse F5 melts and cuts off the current flowing through the high-voltage power supply board 150, i.e., the current flowing through the charging voltage application circuit 151, the developing voltage application circuit 152, and the transfer voltage application circuit 153.

[0164] The first connector C1 is a connector for connecting the sub-board 120 to the main board 110. The first connector C1 and the main connector CM are board-to-board connectors for connecting boards together. At least one of the first connector C1 and the main connector CM may be a floating connector designed to absorb positional errors by moving relative to the main board 110 and the connector board 120.

[0165] The second connector C2 is a connector for connecting the low-voltage power supply board 140 to the sub-board 120. A terminal of the first harness H1 is connected to the second connector C2.

[0166] The third connector C3 is a connector for connecting the main motor 160 to the sub-board 120. A terminal of the second harness H2 is connected to the third connector C3.

[0167] The seventh connector C7 is a connector for connecting the polygon motor 53 to the sub-board 120. A terminal of the sixth harness H6 is connected to the seventh connector C7.

[0168] Here, the transmission path of the power supplied from the low-voltage power supply board 140 and the transmission path of the control signal sent from the ASIC 111 in the second embodiment will be described.

[0169] 9, the low-voltage power supply board 140 supplies power to the DC / DC converter 121 based on a control signal sent from the ASIC 111. The DC / DC converter 121 receives a DC voltage of a first voltage from the AC / DC converter 141 via a second connector C2 and a first fuse F1. As described above, the DC / DC converter 121 converts the DC voltage of the first voltage into a DC voltage of a second voltage that is lower than the first voltage.

[0170] The ASIC 111 is supplied with a DC voltage of the second voltage from the DC / DC converter 121 via the first connector C1, and is supplied with a DC voltage converted into a third voltage by the sub-converter 112.

[0171] The main motor drive circuit 122 is supplied with a DC voltage of the first voltage from the AC / DC converter 141 via the second connector C2 and the second fuse F2. Based on a control signal sent from the ASIC 111, the main motor drive circuit 122 converts the DC voltage of the first voltage into a drive voltage for the main motor 160 and outputs it to the main motor 160 via the third connector C3. The ASIC 111 sends a control signal to the main motor 160 via the first connector C1 and the third connector C3. The ASIC 111 also receives a signal from the main motor 160 via the third connector C3 and the first connector C1.

[0172] The polygon motor drive circuit 123 is supplied with a first DC voltage from the AC / DC converter 141 via the second connector C2 and the third fuse F3. Based on a control signal sent from the ASIC 111, the polygon motor drive circuit 123 converts the first DC voltage into a drive voltage for the polygon motor 53 and outputs it to the polygon motor 53 via the sixth connector C6. The ASIC 111 sends a control signal to the polygon motor 53 via the first connector C1 and the seventh connector C7. The ASIC 111 also receives a signal from the polygon motor 53 via the seventh connector C7 and the first connector C1.

[0173] The charging voltage application circuit 151 receives power from the low-voltage power supply board 140 via the sub-board 120 and the main board 110. More specifically, the main board 110 receives a first DC voltage from the AC / DC converter 141 via the second connector C2. The charging voltage application circuit 151 receives a first DC voltage from the main board 110 via the fourth connector C4. The charging voltage application circuit 151 outputs a charging voltage to the charger 62 based on a control signal sent from the ASIC 111 via the fourth connector C4.

[0174] The developing voltage application circuit 152 receives power from the low-voltage power supply board 140 via the sub-board 120 and the main board 110. More specifically, the main board 110 receives a first DC voltage from the AC / DC converter 141 via the second connector C2. The developing voltage application circuit 152 receives a first DC voltage from the main board 110 via the fourth connector C4. The developing voltage application circuit 152 outputs a developing voltage to the developing roller 64 based on a control signal sent from the ASIC 111 via the fourth connector C4.

[0175] The transfer voltage application circuit 153 receives power from the low-voltage power supply board 140 via the sub-board 120 and the main board 110. More specifically, the main board 110 receives a first DC voltage from the AC / DC converter 141 via the second connector C2. The transfer voltage application circuit 153 receives a first DC voltage from the main board 110 via the fourth connector C4. The transfer voltage application circuit 153 outputs a transfer voltage to the transfer roller 63 based on a control signal sent from the ASIC 111 via the fourth connector C4.

[0176] The ASIC 111 transmits a control signal to the optical device 51 via the sixth connector C6.

[0177] The ASIC 111 receives a command input from the operation panel ASIC 181 via the fifth connector C5, and also transmits a message to the operation panel ASIC 181 via the fifth connector C5.

[0178] Power is supplied to the LCD 182 from the low-voltage power supply board 140 via the sub-board 120 and the main board 110. More specifically, a first DC voltage is supplied to the main board 110 via the second connector C2 from the AC / DC converter 141. The first DC voltage is supplied to the LCD 182 from the main board 110 via the fifth connector C5.

[0179] As described above, the first connector C1 transmits the DC voltage of the first voltage, the DC voltage of the second voltage, and the control signal sent from the ASIC 111. The fifth connector C5 transmits the DC voltage of the first voltage, the DC voltage of the second voltage, and the control signal sent from the ASIC 111. The sixth connector C6 transmits the control signal sent from the ASIC 111.

[0180] In the second embodiment described above, as in the first embodiment, the sub-board 120 on which the DC / DC converter 121 is arranged is located outside the main board 110 and the second metal plate 130, so that the DC / DC converter 121 can be easily replaced by replacing the sub-board 120.

[0181] Although the embodiment has been described above, the image forming apparatus 1 can be modified as appropriate as exemplified below.

[0182] In the above-described embodiment, the sub-board 120 is disposed between the main motor 160 and the main board 110 in the second direction, but the sub-board 120 does not have to be disposed between the main motor 160 and the main board 110 in the second direction. For example, the sub-board 120 and the main motor 160 may be disposed so as to overlap each other in the second direction, or the main board 110 and the main motor 160 may be disposed so as to overlap each other in the second direction.

[0183] In the above-described embodiment, the low-voltage power supply board 140 and the main board 110 are electrically connected via the sub-board 120, but the low-voltage power supply board 140 and the main board 110 may be electrically connected directly without going through the sub-board 120. In this case, the low-voltage power supply board 140 and the main board 110 may be electrically connected by a harness.

[0184] In the above-described embodiment, the high-voltage power supply board 150 and the main board 110 are electrically connected via the sub-board 120, but the high-voltage power supply board 150 and the main board 110 may be electrically connected directly without going through the sub-board 120. In this case, the high-voltage power supply board 150 and the main board 110 may be electrically connected by a harness.

[0185] In the above-described embodiment, the first fuse F1, the second fuse F2, and the third fuse F3 are arranged on the primary side of the DC / DC converter 121, the main motor drive circuit 122, and the polygon motor drive circuit 123, but they may also be arranged on the secondary side, or on both the primary side and the secondary side.

[0186] In the above-described embodiment, the first voltage is 24 V and the second voltage is 3.3 V, but the first voltage and the second voltage can be set arbitrarily. For example, the second voltage may be 5 V, 1.2 V, or 1.1 V.

[0187] In the above-described embodiment, the image forming apparatus 1 is illustrated as having one DC / DC converter, but the image forming apparatus may also have multiple DC / DC converters. For example, multiple DC / DC converters may be connected in parallel to convert to multiple voltages, or multiple DC / DC converters may be connected in series to convert a second voltage to a third voltage that is smaller than the second voltage. Furthermore, at least one of the multiple DC / DC converters may be disposed on the main board.

[0188] In this embodiment, when viewed from the first direction, the upper part of the sub-substrate 120 does not overlap with the low-voltage power supply substrate 140, and the lower part overlaps with the low-voltage power supply substrate 140, but it is also possible for only the upper part, only the front part, or only the rear part of the sub-substrate to overlap with the low-voltage power supply substrate, or for the entire sub-substrate to overlap with the low-voltage power supply substrate when viewed from the first direction.

[0189] In the above-described embodiment, the main connector CM of the main board 110 and the first connector C1 of the sub-board 120 face each other in the first direction, but they may face each other in a direction different from the first direction. For example, if the main connector CM and the first connector C1 face each other in the second direction, the main board 110 is pulled out from the second direction. Also, if the main connector CM and the first connector C1 face each other in the vertical direction, the main board 110 is pulled out from the vertical direction.

[0190] In the above-described embodiment, the first connector C1, the second connector C2, the third connector C3, the fourth connector C4, the fifth connector C5, and the sixth connector C6 were arranged on the mounting surface 120A of the sub-board 120, but at least one of the first connector C1, the second connector C2, the third connector C3, the fourth connector C4, the fifth connector C5, and the sixth connector C6 may not be arranged on the mounting surface 120A.

[0191] In the above-described embodiment, both the main motor drive circuit 122 and the polygon motor drive circuit 123 are arranged on the sub-board 120, but it is also possible to configure at least one of the main motor drive circuit 122 and the polygon motor drive circuit 123 to be arranged on the main board 110.

[0192] In the above-described embodiment, the main board has an ASIC as the main control circuit, but the main board may have a main control circuit other than an ASIC, such as a CPU.

[0193] In the above-described embodiment, the main motor drives the image forming unit and the conveying unit, but the main motor may be configured to drive the image forming unit without driving the conveying unit, or may be configured to drive the conveying unit without driving the image forming unit.Furthermore, the main motor may be configured to drive part of the image forming unit without driving the conveying unit, or part of the conveying unit without driving the image forming unit.

[0194] In the above-described embodiment, the image forming unit 40 is configured to perform so-called direct transfer, in which the toner image formed on the photosensitive drum 61 is transferred to the sheet S by the transfer roller 63. However, the image forming unit may also be configured to perform so-called intermediate transfer, in which the toner image formed on the photosensitive drum is transferred from the intermediate transfer belt to the sheet.

[0195] In the above-described embodiment, the image forming apparatus 1 is a monochrome printer, but the image forming apparatus may be, for example, a color printer. The image forming apparatus may also be a copier, a multifunction peripheral, or the like. In the embodiment, an electrophotographic image forming apparatus is exemplified, but the image forming apparatus may also be, for example, an inkjet image forming apparatus, a dot impact image forming apparatus, or the like.

[0196] The elements described in the embodiments and modifications may be implemented in any combination. [Explanation of symbols]

[0197] 110 Main board 111 ASIC 120 Sub-board 121 DC / DC converter 122 Main motor drive circuit 123 Polygon motor drive circuit 140 Low voltage power supply board 141 AC / DC converter 150 High voltage power supply board 151 Charge voltage application circuit 152 Development voltage application circuit 153 Transfer voltage application circuit 160 Main motor

Claims

1. A main body housing; a photosensitive drum rotatable around a rotation axis extending in a first direction; a main motor for applying a driving force to the photosensitive drum; an AC / DC converter that converts AC voltage supplied from a commercial power source into DC voltage of a first voltage; a main board having an ASIC for controlling the main motor; an image forming apparatus comprising: a sub-board detachable from at least one of the main body housing and the main board, the sub-board being electrically connected to both the main motor and the main board, the sub-board having a DC / DC converter that converts a DC voltage of the first voltage into a DC voltage of a second voltage lower than the first voltage; and a main motor drive circuit that outputs drive power to the main motor based on a control signal sent from the ASIC.

2. 2. The image forming apparatus according to claim 1, wherein the sub-board is disposed between the main motor and the main board in a second direction perpendicular to the up-down direction and the first direction.

3. The sub-substrate is arranged parallel to the main board, 3. The image forming apparatus according to claim 2, further comprising a first connector that is directly connected to the main board without a harness.

4. At least a portion of the sub-board faces the main board in the first direction, 4. The image forming apparatus according to claim 3, wherein the first connector is connected to the main board in the first direction.

5. 5. The image forming apparatus according to claim 4, wherein the first connector transmits the second DC voltage and a control signal sent from the ASIC.

6. a low-voltage power supply board on which the AC / DC converter is arranged, 6. The image forming apparatus according to claim 5, wherein the low-voltage power supply board and the main board are electrically connected via the sub-board.

7. a low-voltage power supply board on which the AC / DC converter is arranged, 2. The image forming apparatus according to claim 1, wherein the sub-board is provided with a second connector to which a terminal of a first harness that connects the low-voltage power supply board and the sub-board is connected.

8. The main body housing includes: a first region that is located outside the photosensitive drum in the first direction and on one side of the photosensitive drum in the first direction; a second region that is located outside the photosensitive drum in the first direction and on the other side of the photosensitive drum in the first direction, the main board, the sub-board, and the main motor are located in the first area, 8. The image forming apparatus according to claim 7, wherein the low-voltage power supply board is located in the second area.

9. 8. The image forming apparatus according to claim 7, wherein the sub-board at least partially overlaps with the low-voltage power supply board when viewed from the first direction.

10. 8. The image forming apparatus according to claim 7, wherein the connection portion between the first harness and the low-voltage power supply board is located closer to the sub-board than to the main board in the vertical direction and in a second direction perpendicular to the first direction.

11. 2. The image forming apparatus according to claim 1, wherein the sub-board further includes a fuse connected in series with the main motor drive circuit.

12. 2. The image forming apparatus according to claim 1, wherein the sub-board further includes a fuse connected in series with the DC / DC converter.

13. an exposure unit including a light source device capable of emitting a beam, a polygon mirror that deflects the beam, and a polygon motor that rotates the polygon mirror; the sub-board further includes a polygon motor drive circuit that outputs drive power to the polygon motor; 2. The image forming apparatus according to claim 1, wherein the polygon motor drive circuit outputs drive power to the polygon motor based on a control signal sent from the ASIC.

14. 8. The image forming apparatus according to claim 7, wherein the mounting surface of the sub-board faces the direction in which the low-voltage power supply board is located.

15. a pickup roller that receives a driving force from the main motor and feeds the sheets stored in the sheet tray toward the photosensitive drum; and a gear train that transmits driving force from the main motor to the pickup roller and is located in a first region; 9. The image forming apparatus according to claim 8, wherein the main board, the sub-board, the main motor, and the pickup roller are arranged in this order in the vertical direction and in a second direction perpendicular to the first direction.

16. At least a portion of the sub-substrate is located on one side of the rotation axis of the photosensitive drum in a vertical direction and in a second direction perpendicular to the first direction, 9. The image forming apparatus according to claim 8, wherein the first harness is located on one side of the rotation axis of the photosensitive drum in the second direction.

Images