JP2020118722A - Image forming device - Google Patents

Abstract

To solve the problem with a configuration in which a first substrate is covered with sheet metal in order to suppress noise from the first substrate, that it is difficult to efficiently cool the first substrate and a second substrate.SOLUTION: An image forming device 101 comprises: a fuser 13; a triac 209 for controlling the supply of mains power to the fuser 13; an AC input circuit board 202 on which the triac is mounted; a power supply board 201 receiving the supply of mains power from the AC input circuit board and generating, and outputting, a DC voltage on the basis of the power supply voltage of the mains power; a substrate base shield 203 for supporting the AC input circuit board and the power supply board on the same plane; a noise shield member 204 fixed to the substrate base shield so as to cover the power supply board with a space therebetween; and a cooling fan 205 for cooling the power supply board. The noise shield member and the substrate base shield form a duct having an inflow port and an outflow port for the cooling airflow generated by the cooling fan, with the triac mounted further downstream of the cooling airflow than the outflow port of the duct of the AC input circuit board.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus including a power supply board and an AC input circuit board.

Image forming apparatuses such as printers and multi-function peripherals include an AC input circuit board for receiving power from a commercial power source. The image forming apparatus also includes a power supply board that converts an AC voltage supplied via the AC input circuit board into a DC voltage and supplies the obtained DC voltage to each load and each board. The power supply board and the AC input circuit board are connected by an AC line, and the power supply board is arranged near the AC input circuit board in order to shorten the AC line from the viewpoint of noise. Further, when the space is limited due to the miniaturization of the device, the power supply board and the AC input circuit board may be arranged side by side on the same plane.

In such an image forming apparatus, in order to shield the noise generated from the power supply board, a configuration is adopted in which the power supply board is covered with a sheet metal having a box shape to shield between the power supply board and the AC input circuit board. ing. Further, since a member such as a switching element and a coil that generates a large amount of heat is mounted on the power supply board, a fan for cooling these members is installed. For example, as shown in Patent Document 1, in order to cool a power supply substrate covered with a shielding sheet metal, an air duct having a side wall of a part of the sheet metal covering the power supply substrate is provided and the air duct is used. A configuration is known in which a power supply board is cooled by means of such a method.

JP, 2017-44986, A

Generally, in an image forming apparatus, electric components that generate heat are mounted on a power supply board, so that it is necessary to place a FAN near the power supply board to actively cool the entire board. Further, for example, the AC input circuit board arranged in the vicinity of the power supply board is also mounted with an electric component that generates a large amount of heat, and thus needs to be cooled.

However, in the above-mentioned conventional technique in which the power supply board is covered with a metal plate to suppress noise from the power supply board, and an air duct whose part is a side wall is provided, an AC input circuit board arranged near the power supply board is provided. There is a problem that the wind path of is blocked.

That is, in the above-described conventional technique, the cooling member for suppressing the noise of the power supply board interferes with the cooling air passage for the AC input circuit board arranged on the same plane as the power supply board, so that the efficiency of the AC input circuit board is improved. There was a problem that it could not be cooled well.

An object of the present invention is to provide an image forming apparatus capable of efficiently cooling a power supply board and an AC input circuit board while suppressing noise from the power supply board.

In order to solve the above problems, the image forming apparatus according to claim 1 is a load that receives a commercial power supply and executes a process for forming an image, and a control that controls the commercial power supply to the load. An element, a first board on which the control element is mounted, and a second power source that receives commercial power from the first board and generates and outputs a predetermined DC voltage based on the power voltage of the commercial power source. The substrate, the third substrate supporting the first substrate and the second substrate on the same plane, and the second substrate were fixed to the third substrate so as to cover the second substrate with a space. A noise shielding member and a cooling fan for cooling the second substrate, wherein the noise shielding member and the third substrate are an inlet and a cooling airflow into which a cooling airflow generated by the cooling fan flows. Is formed, and the control element is mounted downstream of the cooling airflow with respect to the outlet of the duct in the first substrate.

According to the present invention, it is possible to efficiently cool the first substrate and the second substrate while suppressing noise from the first substrate.

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to an embodiment. FIG. 3 is a perspective view showing a substrate arrangement on the back surface of the image forming apparatus of FIG. 1. FIG. 3 is a partially enlarged view of FIG. 2, showing the substrate arrangement with the noise shielding member removed. It is a rear view corresponding to FIG. 3, and is a figure which shows the arrangement relationship of a noise shielding member and a control element. FIG. 3 is a diagram showing an arrangement relationship of various members when viewed from a cooling fan provided on a back surface side of a left side surface of the image forming apparatus of FIG. 1. It is a perspective view corresponding to FIG. 4, and is a figure which shows the flow path of a cooling airflow.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to an embodiment.

In FIG. 1, the image forming apparatus 101 includes four cartridges Pa, Pb, Pc, and Pd that form toner images of respective color components. The four cartridges Pa, Pb, Pc, and Pd are arranged substantially horizontally along the conveyance direction of the intermediate transfer belt 7. The cartridge Pa forms a yellow toner image, the cartridge Pb forms a magenta toner image, the cartridge Pc forms a cyan toner image, and the cartridge Pd forms a black toner image.

The image forming apparatus 101 is provided with four bottle mounting portions corresponding to the four cartridges Pa, Pb, Pc, and Pd. Removable toner bottles Ta, Tb, Tc, and Td are mounted on the respective bottle mounting portions. The toner bottle Ta contains yellow toner, the toner bottle Tb contains magenta toner, the toner bottle Tc contains cyan toner, and the toner bottle Td contains black toner. Is housed. The toner bottles Ta, Tb, Tc, and Td function as a container for containing toner as a developer.

The cartridges Pa, Pb, Pc, and Pd have the same configuration and are attachable to and detachable from the image forming apparatus 101.

The cartridges Pa to Pd have photosensitive drums 1a to 1d, chargers 2a to 2d for charging the photosensitive drums 1a to 1d, and developing units 100a to 100d containing toner. Each of the photosensitive drums 1a to 1d is formed of a cylindrical metal roller, and has a layer of the photoconductor on the surface thereof. The photosensitive drums 1a to 1d rotate in the direction of arrow A in FIG. After the photosensitive drums 1a to 1d are charged by the chargers 2a to 2d, the laser exposure devices 3a to 3d expose the photosensitive drums 1a to 1d based on the image data. As a result, electrostatic latent images are formed on the photosensitive drums 1a to 1d. Then, the developing devices 100a to 100d develop the electrostatic latent images on the photosensitive drums 1a to 1d with toner. As a result, toner images of respective colors are formed on the photosensitive drums 1a to 1d.

The developing units 100a to 100d include magnetic permeability sensors (not shown) that detect the amount of toner accumulated in the developing units 100a to 100d. When it is detected by the magnetic permeability sensor that the amount of toner in the developing devices 100a to 100d has decreased, toner of the corresponding color is supplied to the developing devices 100a to 100d from the corresponding toner bottles Ta to Td.

The intermediate transfer belt 7 is wound around a secondary transfer counter roller 8, a driven roller 17, a first tension roller 18, and a second tension roller 19. The intermediate transfer belt 7 is rotated in the arrow B direction in FIG. 1 by the rotational drive of the secondary transfer counter roller 8. A secondary transfer roller 9 is arranged on the opposite side of the secondary transfer counter roller 8 with respect to the intermediate transfer belt 7. The contact portion between the secondary transfer counter roller 8 and the secondary transfer roller 9 becomes the secondary transfer nip portion T2.

The image forming apparatus 101 includes primary transfer rollers 4 a to 4 d that transfer the toner images on the photosensitive drums 1 a to 1 d onto the intermediate transfer belt 7. While the toner image formed on the photosensitive drum 1 is passing through the primary transfer nip portions T1a to T1d where the photosensitive drums 1a to 1d and the intermediate transfer belt 7 are pressed by the primary transfer rollers 4a to 4d, A primary transfer voltage is applied to each of the transfer rollers 4a to 4d. As a result, the toner images on the photosensitive drums 1a to 1d are transferred to the intermediate transfer belt 7. The toner images formed on the photosensitive drums 1a to 1d are transferred onto the intermediate transfer belt 7 in an overlapping manner, so that the intermediate transfer belt 7 carries a full-color toner image. The toner remaining on the photosensitive drums 1a to 1d is removed by the drum cleaners 6a to 6d, respectively.

On the other hand, a paper feed roller (not shown), a conveyance roller pair 61, and a registration roller pair 62 are arranged on the conveyance path for conveying the recording material S stored in the cassette unit 60. The paper feed roller starts to feed the recording material S stored in the cassette unit 60, and the conveying roller pair 61 conveys the recording material S toward the registration roller pair 62. The registration roller pair 62 adjusts the timing of conveying the recording material S to the secondary transfer nip portion T2 so that the toner image on the intermediate transfer belt 7 is transferred to a desired position on the recording material S.

In the secondary transfer nip portion T2 in which the secondary transfer opposing roller 8 and the intermediate transfer belt 7 are pressed by the secondary transfer roller 9 in response to the secondary transfer voltage being applied to the secondary transfer opposing roller 8. The toner image on the intermediate transfer belt 7 is transferred to the recording material S. The toner remaining on the intermediate transfer belt 7 without being transferred to the recording material S at the secondary transfer nip portion T2 is removed by the belt cleaner 11.

The recording material S on which the toner image has been transferred flows out from the secondary transfer nip portion T2 and is then carried into the fixing device 13. The fixing device 13 includes a fixing roller having a heater and a pressure roller. The toner image on the recording material S is fixed on the recording material S by the heat of the heater and the contact pressure between the fixing roller and the pressure roller. The recording material S on which the toner image is fixed is discharged from the fixing device 13, and is discharged from the image forming apparatus 101 by the discharge roller pair 64. The fixing device 13 functions as a load for receiving a commercial power supply and performing a fixing process for forming an image.

Next, the arrangement relationship of various substrates arranged on the back side of the image forming apparatus 101 will be described.

FIG. 2 is a perspective view showing a substrate arrangement on the back surface of the image forming apparatus of FIG.

In FIG. 2, an AC input circuit board 202 as a first board receives an AC voltage supplied from a commercial power supply 200 at a commercial power supply connector 208, and a power supply board 201 as a second board and a fixing device 13 (see FIG. AC voltage is supplied to the heater (see 1). The heat value of the heater of the fixing device 13 is controlled based on the AC voltage. The supply of the AC voltage to the heater of the fixing device 13 is ON/OFF controlled by the triac 209 mounted on the AC input circuit board 202. The triac 209 as a control element is a member that easily generates heat.

The supply of the AC voltage from the AC input circuit board 202 to the power supply board 201 is output from the AC output connector 207 on the AC input circuit board 202 and input to the power supply board 201 from the AC input connector 206. The AC output connector 207 and the AC input connector 206 are arranged so as to be adjacent to each other with a gap between the AC input circuit board 202 and the power supply board 201. The AC input connector 206 is mounted on the power supply board 201 in the vicinity of the cooling fan 205. The AC voltage is supplied via an AC cable 214 connecting the AC output connector 207 and the AC input connector 206.

The power supply board 201 converts the AC power supply into a predetermined DC voltage based on the power supply voltage of the commercial power supply supplied from the AC input circuit board 202, and supplies the generated DC voltage to each load and each board. The power supply board 201 supplies, for example, a DC voltage to the control board 220, and the DC voltage is output from the DC output connector 221 on the power supply board 201 and input to the control board 220 from the DC input connector 222. That is, the DC voltage is supplied from the power supply board 201 to the control board 220 via the DC cable 223 connecting the DC output connector 221 and the DC input connector 222. The control board 220 controls a load such as a motor arranged in the image forming apparatus 101 and supplies a DC voltage to each load.

The AC input circuit board 202 and the power supply board 201 are on the same plane with respect to the Z axis on a board stand shield 203 made of sheet metal as a supporting board (third board), and vertically in the Y axis direction on the board. They are arranged side by side in parallel. The AC input circuit board 202 and the power supply board 201 are fixed to the board stand shield 203 with, for example, screws. The AC input circuit board 202 and the power supply board 201 are arranged close to each other in order to shorten the AC cable 214 from the viewpoint of noise. Further, since the depth of the image forming apparatus 101 is limited as the size of the image forming apparatus 101 is reduced, the image forming apparatuses 101 are arranged in parallel vertically, for example.

On the upper side and the left side of the substrate platform shield 203, wall surfaces that project vertically in the Z-axis direction are formed. That is, the substrate platform shield 203 is a box type in which the upper side wall 203a is formed on one side of the substrate platform shield 203, that is, the upper side, and the left side wall 203b is formed on the other side of the substrate platform shield 203, that is, the left side. It has such a shape. The board platform shield 203 is fixed to the body frame 218 by means of body mounting portions 216a and 216b, for example, with screws.

The left side wall 203b of the board stand shield 203 and the upper side wall 203a of the board stand shield 203 are provided with a first wire saddle 224 and a second wire saddle 225, respectively. The first wire saddle 224 and the second wire saddle 225 serve to regulate the DC cable 223.

The power supply board 201 is covered with a noise shielding shield 204 made of steel sheet metal which is a noise shielding member, with a space therebetween. The noise shielding shield 204 is fixed to the board stand shield 203 with, for example, a screw. The noise shielding shield 204 has, for example, a U-shaped cross section in order to cover the power supply substrate 201. The noise shield shield 204 is fixed to the substrate stand shield 203, so that the planar substrate stand shield 203 and the noise shield shield 204 having a U-shaped cross section form a tubular duct. Further, the noise shielding shield 204 covers the power supply board 201 to effectively shield the space between the AC input circuit board 202 and the power supply board 201. The noise shielding shield 204 suppresses leakage of the power supply board 201, for example, switching noise from being superimposed on the AC line of the AC input circuit board 202.

The cooling fan 205 (FAN) cools the power supply board 201 and the AC input circuit board 202. Since many heat generating members are mounted on the power supply board 201, the cooling fan 205 is attached near the power supply board 201 for the purpose of actively cooling the power supply board 201. Further, the duct (cylindrical body) formed by fixing the noise shielding shield 204 covering the power supply substrate 201 to the substrate stand shield 203 has an inlet and an outlet for the cooling airflow (wind) from the cooling fan 205. Therefore, the duct functions as an air duct. The heat generating member mounted on the power supply board 201 is efficiently cooled by the cooling airflow generated in the cooling fan 205 and flowing in the duct.

FIG. 3 is a partially enlarged view of FIG. 2, and is a view showing the substrate arrangement with the noise shielding member removed.

In FIG. 3, the power supply board 201 is a typical flyback switching power supply. On the power supply board 201, a diode bridge 227, a switching element 210, and a transformer 226 necessary to convert the AC power input from the AC input connector 206 into a DC voltage are mounted. Although only the connector and the mounting members that easily generate heat are shown in FIG. 3 for convenience, originally, there are many mounting members of the power supply board 201, and all the mounting members can fulfill the function of the power supply board 201. The power supply substrate 201 converts an AC voltage into a DC voltage and outputs a DC voltage of +24V, for example.

As for the AC input circuit board 202, only connectors and mounting members that easily generate heat are shown in FIG. The triac 209 mounted on the AC input circuit board 202 controls ON/OFF of the power supply when the AC voltage input from the commercial power supply connector 208 is supplied to the fixing device 13.

The power supply board 201 and the AC input circuit board 202 are arranged on the board stand shield 203 on the same plane with respect to the Z-axis direction and vertically parallel to the Y-axis direction, and a space between the two boards is required. For example, screws are attached so that only the insulation distance is separated.

FIG. 4 is a rear view corresponding to FIG. 3, and is a diagram showing an arrangement relationship between the noise shielding member and the control element.

In FIG. 4, a noise shielding shield 204 as a noise shielding member shields noise by inserting a shielding plate (sheet metal) between the power supply board 201 and the AC input circuit board 202. The noise shielding shield 204 is configured to shield the vicinity of the mounting of the AC input connector 206 in consideration of workability. That is, the portion of the noise shielding shield 204 facing the AC input connector 206 is cut out in consideration of workability.

The triac 209 (control element) mounted on the AC input circuit board 202 is separated from the end portion of the noise shielding shield 204, that is, the end portion of the duct by a distance L, and is on the X-axis direction (−) side of the noise shielding shield 204. It is arranged to be located in. The distance L is larger than 0 mm, for example, 6.0 mm. By making the distance L larger than 0 mm, the cooling airflow of the cooling fan 205 hits the triac 209 to cool the triac 209.

In addition, in the present embodiment, the triac 209 has been described as the member mounted by being separated from the end portion of the noise shielding shield 204 by the distance L. However, the member mounted at a distance L from the end of the noise shielding shield 204 is not limited to the triac 209, and any member that is mounted on the AC input circuit board 202 and easily generates heat may be used. It is preferable to place it at the position. In this case, the mounting member is not limited to one member and may be a plurality of members.

FIG. 5 is a diagram showing an arrangement relationship of various members as seen from the direction of the cooling fan provided on the back surface side of the left side surface of the image forming apparatus of FIG.

In FIG. 5, the cooling fan 205 is attached so as to blow a cooling airflow toward the power supply board 201, and has a structure for positively cooling the power supply board 201. In the state where the noise shielding shield 204 is attached to the board platform shield 203, the two members form a duct. As a result, the cooling airflow blown from the cooling fan 205 reaches the left side wall 203b of the substrate stand shield 203 provided so as to face the flow direction of the cooling airflow. Thereby, the cooling airflow efficiently cools the entire power supply board 201, that is, all the members mounted on the power supply board 201.

Next, the cooling airflow that flows in the air duct formed by the substrate base shield 203 and the noise shielding shield 204 will be described in detail.

FIG. 6 is a perspective view corresponding to FIG. 4, and is a view showing a flow path of a cooling air flow.

In FIG. 6, the direction of the cooling airflow blown from the cooling fan 205 to the power supply board 201 is indicated by an arrow. The cooling airflow blown from the cooling fan 205 toward the power supply board 201 passes through the air duct formed by the board stand shield 203 and the noise shielding shield 204 and collides with the left side wall 203b of the board stand shield 203. The airflow colliding with the left side wall 203b of the substrate platform shield 203 flows in the Y-axis (−) direction because the upper sidewall 203a of the substrate platform shield 203 is in the Y-axis (+) direction. On the left side wall 203b of the board base shield 203, the cooling airflow flowing in the Y-axis (−) direction hits the triac 209 which is mounted at a distance L from the end of the noise shielding shield 204, and the triac 209 is mounted on the triac 209. Cooling.

That is, while the cooling airflow blown from the cooling fan 205 toward the power supply board 201 efficiently cools the members mounted on the power supply board 201, the triac 209, which is the heat generating member on the AC input circuit board 202, is also cooled. Cooling. This allows one cooling fan 205 to efficiently cool the members mounted on the two substrates.

In the present embodiment, the cooling airflow 219a generated by the cooling fan 205 has, for example, a wind speed of 5 m/s. For example, when the noise shielding shield 204 is not provided, the wind speed near the triac 209 is about 0.6 m/s. turn into. On the other hand, by attaching the noise shielding shield 204 to the board base shield 203 to form the duct, the wind speed of the cooling air flow 219c near the triac 209 becomes, for example, 1.7 m/s. That is, by attaching the noise shielding shield 204 to the board base shield 203 to form a duct, the cooling airflow for cooling the triac 209 arranged on the AC input circuit board 202 is, for example, about three times as fast as the conventional wind speed. A cooling air flow can be secured.

As described above, in the present embodiment, the noise shielding shield 204 is attached to the board base shield 203 so as to cover the power supply board 201, so that the cooling airflow also flows to the triac 209 which is a heat generating member on the AC input circuit board 202. 219c hits. As a result, the rated temperature can be protected by, for example, applying a cooling air flow having a wind speed of 1.7 m/s to the triac 209 which is a heat generating member that exceeds the rated temperature in a windless state. Further, at this time, it is not necessary to add a new temperature rise prevention measure member.

According to the present embodiment, the noise shielding shield 204 is provided in the board configuration in which the power supply board 201 and the AC input circuit board 202 are arranged on the same plane on the Z axis and are arranged in parallel vertically in the Y axis direction. It can be utilized as a part of an air duct when cooling the power supply board 201. Further, since the heat generating member on the AC input circuit board 202 is mounted at a distance L from the end opening of the noise shielding shield 204, not only the power supply board 201 is cooled by the cooling fan 205 but also the AC input circuit board. The heat generating member on 202 can also be cooled. Moreover, in this case, it is not necessary to change the number or size of the cooling fans 205.

In the present embodiment, the noise shielding member and the board base shield form a duct having an inlet and an outlet for the cooling airflow, and a control element of the AC input circuit board is located downstream of the airflow outlet of the duct. The configuration to be mounted on is applied to the image forming apparatus. However, with such a configuration, as long as the AC input circuit board 202 and the power supply board 201 are provided in parallel on the same plane and the apparatus includes the noise shielding member and the cooling fan 205 that shield the power supply board 201, the image forming apparatus It can also be applied to other devices.

201 power supply board 202 AC input circuit board 203 board stand shield (support board)
203a Upper side wall 203b Left side wall
204 Noise shielding shield (noise shielding member)
205 Cooling Fan 206 AC Input Connector 207 AC Output Connector 208 Commercial Power Supply Connector 209 TRIAC (Control Element)
210 switching element 214 AC cable 220 control board 226 transformer 227 bridge diode

Claims (9)

A load that executes the processing for forming an image by receiving the supply of commercial power,
A control element for controlling the supply of commercial power to the load,
A first substrate on which the control element is mounted,
A second substrate which receives a commercial power supply from the first substrate and generates and outputs a predetermined DC voltage based on the power supply voltage of the commercial power supply;
A third substrate that supports the first substrate and the second substrate on the same plane;
A noise shielding member fixed to the third substrate so as to cover the second substrate with a space in between;
A cooling fan for cooling the second substrate,
The noise shielding member and the third substrate form a duct having an inlet through which the cooling airflow generated by the cooling fan flows in and an outlet through which the cooling airflow flows out, and the control element includes the The image forming apparatus is mounted on the downstream side of the cooling airflow with respect to the outlet of the duct in the first substrate. The image forming apparatus according to claim 1, wherein the first substrate and the second substrate are arranged in parallel on the third substrate. The image forming apparatus according to claim 2, wherein the first substrate and the second substrate are respectively arranged in parallel with a flowing direction of the cooling airflow. A side wall of the third substrate facing the cooling airflow and a side adjacent to the one side and facing the control element with the cooling airflow interposed therebetween have side walls on which the cooling airflow flowing out of the duct collides. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided. The image forming apparatus according to claim 4, wherein each of the side walls is formed by bending an end portion of the third substrate. The first board includes an AC output connector, the second board includes an AC input connector, and the AC output connector and the AC input connector are respectively provided between the first board and the second board. The image forming apparatus according to any one of claims 1 to 5, wherein the image forming apparatuses are arranged so as to be adjacent to each other with a gap therebetween. The image forming apparatus according to claim 6, wherein a portion of the noise shielding member facing the AC input connector is cut out. 8. The first board is an AC input circuit board, the second board is a power board, and the third board is a board stand shield. 2. The image forming apparatus according to item 1. 9. The image forming apparatus according to claim 8, wherein a diode bridge for converting an AC power supply into a DC voltage, a switching element, and a transformer are mounted on the power supply board.

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