Electric circuit and image formation device

Abstract

To provide a circuit board capable of protecting an electronic component from damage while keeping life of the electronic component mounted on the circuit board.SOLUTION: An electric circuit includes a protection circuit board 520 having a board surface 525 on which a varistor (521) is arranged, and an element cover 530 forming a storage space (538) for storing the varistor (521) on the board surface 525. A first portion of the element cover 530 is in contact with the board surface 525, and an opening is formed between a second portion of the element cover 530 different from the first portion and the board surface 525. An airflow path passing through the opening and communicating from the outside of the element cover 530 to the varistor (521) in the housing space (538) is formed. The element cover 530 has a shielding rib (535) disposed between the opening and the varistor (521) stored in the housing space (538).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electric circuit including a circuit board on which electronic components are mounted, and an image forming apparatus including such an electric circuit. [Background technology]

[0002] An image forming apparatus includes a power supply board, a high-voltage board, a control board, and other components mounted on it to control electrical components such as various motors, sensors, and switches. To electrically protect the electronic components mounted on these circuit boards from excessive voltages and currents, the image forming apparatus is provided with a protection circuit board with a protection circuit. These circuit boards are primarily located in the rear space of the image forming apparatus main body.

[0003] Each circuit board is removed and replaced due to breakdowns or maintenance. Furthermore, in order to reduce the size of image forming devices, it is also necessary to arrange the circuit boards in a space-saving manner. Therefore, when assembling an image forming device or replacing components, care must be taken not to damage the electronic components mounted on the circuit boards. Patent Document 1 proposes an electric circuit in which the electronic components are covered with a cover, and the circuit board itself is further covered with a box-shaped component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-110154 Summary of the Invention [Problem to be solved by the invention]

[0005] Covering the circuit board itself with components increases the cost of the components and requires more space for installation in the image forming device. Furthermore, covering electronic components with a cover prevents them from being cooled by the surrounding air during operation, resulting in high temperatures. This can cause malfunctions and shorten the lifespan of the electronic components.

[0006] In view of the above-mentioned problems, the main object of the present invention is to provide an electric circuit that can protect electronic components mounted on a circuit board from damage while maintaining the life of the electronic components. [Means for solving the problem]

[0007] The electrical circuit of the present invention comprises a circuit board having a first surface on which electronic components are arranged, and a cover that forms a storage space on the first surface for storing the electronic components, wherein a first portion of the cover contacts the first surface of the circuit board, and an opening is formed between a second portion of the cover that is separate from the first portion and the first surface of the circuit board, and an airflow path is formed through the opening that communicates from outside the cover to the electronic components in the storage space, and the cover has a shielding member arranged between the opening and the electronic components stored in the storage space. [Effects of the Invention]

[0008] According to the present invention, it is possible to protect electronic components mounted on a circuit board from damage while maintaining the life of the electronic components. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an inkjet recording apparatus. [Figure 2] Layout diagram of electrical circuits. [Figure 3] FIG. [Figure 4] FIG. 4 is a diagram illustrating the configuration of the protection circuit board with the element cover attached. [Figure 5] FIG. 4 is a diagram illustrating the configuration of the protection circuit board with the element cover attached. [Figure 6] 10(a) and 10(b) are explanatory diagrams of the configuration of the element cover. [Figure 7] FIG. 4 is an explanatory diagram of a state in which the protection circuit board is attached to the cooling module. [Figure 8]10A and 10B are explanatory diagrams of another example of a method for fixing the element cover. [Figure 9] 10A and 10B are explanatory diagrams of another example of a method for fixing the element cover. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] FIG. 1 is a configuration diagram of an inkjet recording apparatus, which is an image forming apparatus of this embodiment. The inkjet recording apparatus 100 of this embodiment is a sheet-fed image forming apparatus that produces a finished product by forming an ink image on a sheet using two liquids, a reaction liquid and ink. The inkjet recording apparatus 100 includes a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a paper discharge stacking module 7000. A cut sheet on which an image is to be printed is supplied from the paper feed module 1000, undergoes predetermined processing related to image formation in each module, and is then discharged to the paper discharge stacking module 7000.

[0012] The paper feed module 1000 includes multiple (three tiers in this embodiment) storage cabinets 1100a-1100c. Each of the storage cabinets 1100a-1100c can store sheets. Each of the storage cabinets 1100a-1100c can be pulled out toward the front of the device, and is pulled out toward the front of the device to store sheets. The paper feed module 1000 feeds sheets one by one to the print module 2000. To achieve this, each of the storage cabinets 1100a-1100c is provided with a separation belt and a transport roller. Note that the number of storage cabinets 1100a-1100c is an example, and there may be one, two, four or more tiers.

[0013] The print module 2000 forms an image on a sheet fed from the paper feed module 1000. The print module 2000 includes a pre-imaging registration correction unit (not shown), a print belt unit 2200, and a recording unit 2300. The pre-imaging registration correction unit corrects the inclination and position of the sheet fed from the paper feed module 1000 and conveys the sheet to the print belt unit 2200.

[0014] The print belt unit 2200 and the recording unit 2300 are disposed facing each other across the sheet transport path, downstream of the pre-imaging registration correction unit in the sheet transport direction. The print belt unit 2200 adsorbs and transports the sheet transported from the pre-imaging registration correction unit. The recording unit 2300 is a sheet processing unit that forms an image by performing a recording process (printing) on ​​the sheet transported by the print belt unit 2200 from above using a recording head. The recording head prints by ejecting ink onto the sheet. As the sheet is adsorbed and transported by the print belt unit 2200, a constant clearance is maintained between the sheet and the recording head.

[0015] A plurality of recording heads are arranged along the sheet transport direction. The recording heads of this embodiment are five line-type recording heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and K (black), as well as the reaction liquid. The number of colors and recording heads is not limited to five. The inkjet method can employ a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, or the like. Ink of each color is supplied to the recording head from an ink tank (not shown) via an ink tube.

[0016] The sheet printed by the recording unit 2300 is transported by the print belt unit 2200. An inline scanner (not shown) is disposed downstream in the transport direction from the recording unit 2300. The inline scanner is used to detect misalignment and color density of the image formed on the sheet and correct the printed image.

[0017] The drying module 3000 dries the sheet on which an image has been formed by the print module 2000. By drying the sheet, the drying module 3000 reduces the liquid component contained in the ink and improves the fixation of the ink to the sheet. The drying module 3000 includes a decoupling unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400.

[0018] The sheet printed by the recording unit 2300 of the print module 2000 is transported to the decoupling unit 3200 in the drying module 3000. The decoupling unit 3200 weakly holds the sheet by air pressure from above and belt friction while transporting it. This prevents the portion of the sheet remaining on the print belt unit 2200 from shifting, while the sheet straddles the decoupling unit 3200 and the print belt unit 2200.

[0019] The sheet conveyed from the decoupling section 3200 is attracted to and conveyed by the drying belt unit 3300, and at the same time, hot air is blown onto the ink-applied surface (image printed surface) from the hot air blowing section 3400 arranged above the belt, drying the ink-applied surface. Note that the drying method may be configured by combining a method of applying hot air, a method of irradiating the sheet surface with electromagnetic waves (ultraviolet rays, infrared rays, etc.), or a conductive heat transfer method by contact with a heating element.

[0020] The fixing module 4000 heats the sheet dried in the drying module 3000 to dry the ink, thereby fixing the image to the sheet. The fixing module 4000 includes a fixing belt unit 4100 having an upper belt unit 4110 and a lower belt unit 4120. The fixing module 4000 passes the sheet conveyed from the drying module 3000 between the heated upper belt unit 4110 and lower belt unit 4120, thereby allowing the ink solvent to sufficiently penetrate (fix) the sheet.

[0021] The cooling module 5000 cools the sheet on which the image has been fixed by the fixing module 4000, solidifying the ink softened by heating and suppressing changes in the temperature of the sheet caused by downstream devices. The cooling module 5000 includes multiple cooling units 5001. The multiple cooling units 5001 cool the high-temperature sheet conveyed from the fixing module 4000. Each cooling unit 5001 is configured to increase the pressure inside the cooling box by drawing in outside air with a fan into the cooling box, and to cool the sheet by blowing air from nozzles formed in the conveyance guide onto the sheet. The multiple cooling units 5001 are arranged on both sides of the conveyance path, allowing the sheet to be cooled from both sides.

[0022] A transport path switching unit is provided inside the cooling module 5000. The transport path switching unit switches the transport path of the sheet depending on whether the sheet is transported to the reversing module 6000 or to a double-sided transport path used for double-sided printing.

[0023] During double-sided printing, the sheet is transported to a transport path below the cooling module 5000 and then transported through a double-sided transport path including the fixing module 4000, drying module 3000, print module 2000, and paper feed module 1000. The double-sided transport section of the fixing module 4000 is provided with a first reversing unit 4200 that reverses the sheet from front to back. The sheet is transported to the first reversing unit 4200, then reversed and transported toward the drying module 3000, thereby reversing the print side of the image. By passing through the first reversing unit 4200, printing on the back side of the sheet becomes possible. The sheet is then transported again to the pre-imaging registration correction unit, print belt unit 2200, and recording unit 2300 of the print module 2000, where it is printed.

[0024] The inversion module 6000 includes a second inversion unit 6400. The inversion module 6000 can invert the front and back sides of the conveyed sheet using the second inversion unit 6400. This allows the orientation of the front and back sides of the discharged sheet to be changed. The discharge stacking module 7000 includes a top tray 7200 and a stacking unit 7500. The discharge stacking module 7000 aligns and stacks the sheets conveyed from the inversion module 6000 on the top tray 7200 or the stacking unit 7500.

[0025] (Circuit board layout) FIG. 2 is an explanatory diagram of the arrangement of the electric circuits mounted in each module of the inkjet recording apparatus 100. The electric circuits include a circuit board on which electronic components are mounted. FIG. 2 is a rear view of the inkjet recording apparatus 100. The electric circuits are used, for example, for predetermined operations related to image formation in each module. FIG. 2 illustrates the arrangement of a protection circuit board 520 on which a protection circuit is mounted, as an example of a circuit board equipped with the electric circuits. Image forming apparatuses generally include a protection circuit for electrically protecting the electronic components mounted on the circuit board in case an excessive voltage is input. The protection circuit is provided near the external power input unit.

[0026] In a system consisting of multiple modules, such as the inkjet recording apparatus 100 of this embodiment, a protection circuit board 520 is provided in each module. The protection circuit board 520 is attached to the rear side of each module. In the inkjet recording apparatus 100 of this embodiment, a total of eight protection circuit boards 520 are arranged in six of the seven modules. The peripheral configuration of the protection circuit boards 520 of each module is not the same, but is unique to each module.

[0027] FIG. 3 is an explanatory diagram of the configuration of a protection circuit board 520. The protection circuit board 520 includes a varistor 521, which is a voltage-dependent resistor that electrically protects other electronic components mounted on the protection circuit board 520 when an excessive voltage is input. A connector 523, to which an external input terminal is connected, is provided on a board surface 525, facing the varistor 521. Cover mounting holes 522 are provided on the left and right sides of the varistor 521 for mounting an element cover, which will be described later. A plurality of board mounting holes 524 are provided on the edge of the protection circuit board 520. The protection circuit board 520 is fixed to a mounting plate, which is a sheet metal part and will be described later, with screws through the board mounting holes 524. The mounting plate is attached to a predetermined position on the module.

[0028] 4 and 5 are explanatory diagrams of the configuration of the protection circuit board 520 with the element cover attached. Fig. 4 is a diagram showing the attached state of the element cover 530 as seen from the mounting surface side (board surface 525: component surface side) of the protection circuit board 520, and Fig. 5 is a diagram as seen from the solder surface.

[0029] The element cover 530 is attached so as to cover the varistor 521 of the protection circuit board 520. The element cover 530 comes into contact with the board surface 525 via a side wall 537 having a notch 533. The element cover 530 has a flexible claw 532 which is a flexible support part with a fixed claw 531 formed at its tip. The fixed claw 531 is passed through a cover mounting hole 522 of the protection circuit board 520 and is engaged with the solder surface of the protection circuit board 520. At this time, the fixed claw 531 bends the flexible claw 532 before passing through the cover mounting hole 522. The bending of the flexible claw 532 is released, and the fixed claw 531 is engaged with the solder surface. With the fixed claw 531 engaged with the solder surface, the element cover 530 is fixed to the board surface 525 and is integrated with the protection circuit board 520.

[0030] By attaching element cover 530, varistor 521 protruding from board surface 525 of protection circuit board 520 is protected. In other words, when removing protection circuit board 520 or working near protection circuit board 520 during assembly or maintenance work, varistor 521 will not be accidentally touched. As a result, varistor 521 is protected from damage.

[0031] Figure 6 is an explanatory diagram of the configuration of the element cover 530. Figure 6(a) is a perspective view of the element cover 530, and Figure 6(b) is a view of Figure 6(a) seen from below. The element cover 530 of this embodiment is made of flame-retardant resin and is produced by, for example, injection molding.

[0032] As described above, the element cover 530 has a side wall 537 on its outer periphery. When the side wall 537 comes into contact with the board surface 525 of the protection circuit board 520, the element cover 530 encloses the varistor 521 inside. A notch 533 is provided in part of the side wall 537. When the side wall 537 comes into contact with the board surface 525, an opening (gap) is formed between the notch 533 and the board surface 525. This opening forms an airflow path (communication path 534) that communicates from the outside to the inside of the element cover 530. Therefore, heat generated by the varistor 521 inside the element cover 530 is discharged to the outside of the element cover 530 through the opening.

[0033] The opening will be described from another perspective. In this embodiment, the sidewall 537 includes a first portion and a second portion. The first portion of the sidewall 537 is a portion that contacts the substrate surface 525. The second portion of the sidewall 537 is a portion where the notch 533 is provided. That is, an opening is formed between the second portion of the sidewall 537 and the substrate surface 525. The sidewall 537 also includes an edge portion 539. At least a portion of the edge portion 539 contacts the substrate surface 525. Conveniently, the edge portion 539 includes a first edge corresponding to the first portion of the sidewall 537 and a second edge corresponding to the second portion of the sidewall 537. That is, the edge portion 539 of the sidewall 537 includes a first edge that contacts the substrate surface 525 and a second edge that does not contact the substrate surface 525. Here, the second edge portion is formed as the notch 533 relative to the first edge portion.

[0034] A varistor storage space 538 for containing the varistor 521 is formed inside the element cover 530. A shielding rib 535 is provided as a shielding member between the varistor 521 arranged in the varistor storage space 538 and the cutout 533. The end of the shielding rib 535 contacts the substrate surface 525, as do the side walls 537. The shielding rib 535 connects the varistor storage space 538 and the cutout 533 via two crank-shaped communication paths 534 on the left and right. Because of the shielding by the shielding rib 535, the varistor 521 in the varistor storage space 538 cannot be directly seen from the cutout 533 (opening). In other words, the communication path 534 is formed to bypass the shielding rib 535; conversely, the shielding rib 535 does not block the airflow path from the outside of the element cover 530 to the varistor storage space 538. In this way, the shielding rib 535 divides the varistor storage space 538 into a first space facing the opening and a second space in which the varistor 521 is disposed. The shielding rib 535 also branches the path connecting the first space to the second space into two branch paths.

[0035] The element cover 530 has a top surface that is approximately parallel to the mounting surface (substrate surface 525). The first and second portions of the side wall 537 and the shielding rib 535 each include a plate portion that is continuous with the top surface and extends approximately perpendicular to the mounting surface.

[0036] As described above, since the varistor storage space 538 and the cutout 533 communicate with each other, air is less likely to become trapped inside the varistor storage space 538, making it possible to suppress a rise in temperature of the varistor 521. The size of the cutout 533 and the size of the communication path 534 are determined according to the type of electronic component to be housed inside the element cover 530.

[0037] Because the communication path 534 has a crank-shaped labyrinth structure, the varistor storage space 538 is configured so that foreign matter is less likely to enter through the cutout 533. Even if foreign matter does enter, because there are two communication paths 534, it is unlikely that the path between the cutout 533 and the varistor storage space 538 will be completely blocked. Furthermore, a connector 523 of the protection circuit board 520 is disposed at a position facing the cutout 533 (opening) on ​​the outside of the element cover 530. The size of the connector 523 is equal to or larger than the projected area of ​​the opening formed by the cutout 533 and the board surface 525. Therefore, the connector 523 functions as a shield that prevents foreign matter from entering the cutout 533. Note that although an example in which the connector 523 is provided as the shield is shown here, the shield may be another electronic component.

[0038] The communication path 534 and the notch 533 can be formed in the direction of removal of the mold used in injection molding. This allows for precise adjustment of the height of the notch 533. The shielding rib 535 can also be easily processed, allowing for a high degree of freedom in the shape of the communication path 534.

[0039] In this embodiment, a configuration has been described in which an opening is formed by the cutout 533 and the substrate surface 525. As a modified example, a configuration may be adopted in which an opening (hole) is provided in the side wall 537 itself instead of the cutout 533. In other words, an opening whose entire periphery is surrounded by the side wall 537 may be provided. In this case, it can be considered that an opening and a third portion, which is yet another portion of the side wall 537, are disposed between the second portion of the side wall 537 and the substrate surface 525. Also, multiple openings may be provided. In any case, it is sufficient that an opening is provided that connects the varistor storage space 538 to the external space of the element cover 530 with at least a portion of the side wall 537 in contact with the substrate surface 525, and that the electronic components in the varistor storage space 538 cannot be seen from the external space.

[0040] Fig. 7 is an explanatory diagram of the state in which the protection circuit board 520 is attached to the cooling module 5000. As described above, the protection circuit board 520 is attached to the rear side of the cooling module 5000. Fig. 7 illustrates a state in which the rear exterior cover of the cooling module 5000 has been removed to expose the protection circuit board 520. The same configuration is used when the protection circuit board 520 is attached to another module.

[0041] The protection circuit board 520 is attached to the mounting plate 550 with the element cover 530 attached. The protection circuit board 520 is attached to the cooling module 5000 by fixing the mounting plate 550 to the frame of the cooling module 5000. Because the electronic components (varistors 521) of the protection circuit board 520 are protected by the element cover 530, there is no need to provide a separate protective cover or the like to protect the entire protection circuit board 520. For this reason, the protection circuit board 520 can also be attached directly below the exterior cover.

[0042] This configuration allows for greater freedom in the placement of the protection circuit board 520. Furthermore, the number of components used in the protection circuit board 520 is reduced, which is also effective in terms of cost reduction. The electrical circuit of this embodiment is configured entirely with the protection circuit board 520 and the element cover 530 on the board, and is therefore less affected by the surrounding configuration. This allows for the common use of the electrical circuit configuration consisting of the protection circuit board 520 and the element cover 530, even in cases where the internal configurations differ among multiple modules, as in the inkjet recording apparatus 100 of this embodiment.

[0043] 8 and 9 are explanatory diagrams of another example of a method for fixing the element cover 530. In Fig. 8, the element cover 530 is fixed to the protection circuit board 520 with a screw 541. In Fig. 8, the screw is fastened from the board surface 525 side of the protection circuit board 520.

[0044] 9(a) and 9(b), screws are fastened from the solder surface side of the protection circuit board 520. As shown in Fig. 9(a), a female screw is provided on the element cover 530 side, and as shown in Fig. 9(b), screws are fastened from the solder surface side (the side opposite to the board surface 525).

[0045] As described above, in the electric circuit of this embodiment, the element cover 530 can protect the electronic component (varistor 521) mounted on the circuit board (protection circuit board 520) from damage. When the element cover 530 is attached to the protection circuit board 520, heat generated in the electronic component (varistor 521) is released through the opening provided in the element cover 530. This makes it possible to suppress a rise in temperature of the electronic component (varistor 521). Furthermore, since there is no need to use a separate cover that covers the entire circuit board (protection circuit board 520), the space required to attach the circuit board (protection circuit board 520) to a device can be made smaller than before.

[0046] The above description has been given using the varistor 521 as an example of an electronic component protected by the element cover 530, but the electronic component to be protected is not limited to this, and any component mounted on a circuit board can be an electronic component to be protected. Furthermore, the element cover 530 may be provided so as to cover multiple electronic components mounted on the circuit board. Furthermore, multiple element covers 530 may be attached to the circuit board.

[0047] The circuit board is not limited to the protection circuit board 520, and the element cover 530 can be used for any circuit board on which electronic components can be mounted, such as a power supply board, a high-voltage board, a control board, etc. In addition, although the above description has been given of a case where electronic components are mounted on one side of the circuit board, the element cover 530 can also be used on both sides in a case where electronic components are mounted on both sides of the circuit board.

Claims

1. a circuit board having a first surface on which electronic components are arranged; a cover that forms a storage space for storing the electronic components on the first surface, a first portion of the cover contacting the first surface of the circuit board; an opening is formed between a second portion of the cover, which is different from the first portion, and the first surface of the circuit board; an airflow path is formed through the opening, communicating from the outside of the cover to the electronic component in the storage space; The cover has a shielding member disposed between the opening and the electronic component housed in the housing space. Electrical circuit.

2. an edge of the cover including a first edge corresponding to the first portion and a second edge corresponding to the second portion; the first edge of the cover contacts the first surface of the circuit board; the second edge of the cover is formed as a notch relative to the first edge; The opening is formed between the notch and the first surface.

2. The electrical circuit of claim 1.

3. The shielding member is arranged so that the electronic component cannot be seen through the opening.

2. The electrical circuit of claim 1.

4. the path is formed to bypass the shielding member, The shielding member is arranged so as not to block the path.

2. The electrical circuit of claim 1.

5. the cover includes a flexible support portion and a fixing claw disposed at a tip of the flexible support portion, the circuit board has a mounting hole through which the flexible support portion passes; The fixing claw is engaged with a second surface of the circuit board opposite to the first surface.

2. The electrical circuit of claim 1.

6. The shielding member divides the storage space into a first space facing the opening and a second space in which the electronic components are disposed.

2. The electrical circuit of claim 1.

7. the cover has a top surface portion that is substantially parallel to the first surface of the circuit board, each of the first portion, the second portion, and the shielding member includes a plate portion that is continuous with the top surface portion and extends substantially perpendicular to the first surface of the circuit board; An end of the shielding member is in contact with the first surface of the circuit board.

7. The electric circuit of claim 6.

8. The shielding member branches the path into two branch paths each communicating from the first space to the second space.

7. The electric circuit of claim 6.

9. The shielding member has a labyrinth structure, and each of the branch paths of the two systems is formed in a crank shape.

9. The electrical circuit of claim 8.

10. a shield is disposed on the first surface of the circuit board at a position outside the cover and facing the opening, 2. The electrical circuit of claim 1.

11. The shielding object has a size equal to or larger than the projected area of ​​the opening.

11. The electrical circuit of claim 10.

12. The shielding member includes a connector mounted on the circuit board.

12. The electrical circuit of claim 11.

13. The cover is fixed to the circuit board with screws.

2. The electrical circuit of claim 1.

14. The electronic component is a protection circuit for electrically protecting other electronic components mounted on the circuit board.

2. The electrical circuit of claim 1.

15. The electronic component is a varistor.

2. The electrical circuit of claim 1.

16. an electric circuit according to claim 1; a module for performing a predetermined operation related to image formation, The electric circuit is used for the predetermined operation of the module. Image forming device.

17. The circuit board is a protection circuit board on which a protection circuit for electrically protecting other electronic components mounted on the circuit board is mounted.

17. The image forming apparatus according to claim 16.

Images