electronic machines

Abstract

To provide electronic equipment that can suppress interference from high-voltage output with a simple configuration. [Solution] An electronic device according to one embodiment of the present invention comprises a high-voltage circuit board and a conductor. The high-voltage circuit board has a plurality of high-voltage output circuits formed thereon that generate a high voltage supplied to a part used in the electrophotographic development process. The conductor is provided in the space between the plurality of high-voltage output circuits and is electrically grounded.

Description

Technical Field

[0001] The present technology relates to an electronic device applicable to a copying machine or the like.

Background Art

[0002] Patent Document 1 describes an image forming apparatus including a high-voltage substrate. The high-voltage substrate is a substrate that generates a high voltage for supplying to a developing roller or the like used in an electrophotographic system. In the high-voltage substrate, a plurality of high-voltage circuits are formed in one substrate, and high voltages for applying to a developing roller or the like are independently output by each high-voltage circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a plurality of high-voltage circuits are provided on one substrate as in Patent Document 1, depending on the magnitude of the voltage generated in each high-voltage circuit and the distance between the high-voltage circuits, it is conceivable that the high-voltage outputs interfere with each other. Further, in the case of miniaturizing the substrate, the interference of the high-voltage outputs may appear more prominently. For this reason, a technology for suppressing the interference of the high-voltage output with a simple configuration is required.

[0005] In view of the above circumstances, an object of the present invention is to provide an electronic device capable of suppressing the interference of the high-voltage output with a simple configuration.

Means for Solving the Problems

[0006] To achieve the above object, an electronic device according to one aspect of the present invention includes a high-voltage circuit board and a conductive object. The high-voltage circuit board has multiple high-voltage output circuits formed therein that generate high voltages supplied to the parts used in the electrophotographic development process. The conductive material is provided in the space between the multiple high-voltage output circuits and is electrically grounded.

[0007] In this electronic device, a grounded conductive material is placed in the space between multiple high-voltage output circuits on a high-voltage circuit board. This conductive material, for example, inhibits capacitive coupling between the high-voltage output circuits. This makes it possible to suppress interference of high-voltage outputs with a simple configuration.

[0008] The conductive material may be a conductive member having a predetermined function in the electronic device.

[0009] The conductive material may be a heat sink provided on the high-voltage circuit board.

[0010] The conductive material may be a grounded metal member that constitutes the body of the electronic device.

[0011] The plurality of high-voltage output circuits may include a set of high-voltage output circuits arranged adjacent to each other, each having a leaded component that protrudes from the substrate surface of the high-voltage circuit board and generates a high voltage. In this case, the conductive material may be provided in the space between the leaded components provided in each of the set of high-voltage output circuits.

[0012] The lead component may also be a capacitor connected to the secondary side of a step-up transformer. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing an example configuration of an image forming apparatus according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing an example of the circuit configuration of a high-voltage circuit board. [Figure 3] Figure 2 is a schematic circuit diagram illustrating the high-voltage section of the high-voltage circuit board shown. [Figure 4] It is a schematic diagram showing an example of the circuit configuration of a high-voltage circuit board cited as a comparative example. [Figure 5] It is a schematic circuit diagram for explaining the high-voltage portion of the high-voltage circuit board shown in FIG. 4.

Embodiments for Carrying Out the Invention

[0014] <First Embodiment> Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] [Image Forming Apparatus] FIG. 1 is a block diagram showing a configuration example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 is an apparatus that forms an image on a sheet by an electrophotographic method, and includes a photosensitive drum, a charging roller that charges the photosensitive drum, a developing roller that attaches toner to an electrostatic latent image on the surface of the photosensitive drum, a transfer roller for primary or secondary transfer of the toner image, and the like.

[0016] The image forming apparatus 100 is configured as, for example, a copying machine, a printer, a facsimile machine, or a multifunction peripheral (MFP) having a plurality of these functions. In addition, any type of apparatus capable of forming an image on a sheet may be used. In the present embodiment, the image forming apparatus 100 is an example of an electronic device.

[0017] As shown in FIG. 1, the image forming apparatus 100 includes a control board 10, a high-voltage circuit board 20, and an image forming unit 30.

[0018] The control board 10 is a board on which a control circuit for controlling the image forming apparatus 100 is mounted. In the control board, arithmetic processing related to the operation of the image forming apparatus 100 is executed, and a control signal for controlling each part of the image forming apparatus 100 is generated based on the result of the arithmetic processing.

[0019] The high-voltage circuit board 20 is a board on which a plurality of high-voltage output circuits 21 are formed. The high-voltage circuit board 20 outputs the high voltage output from each high-voltage output circuit 21 to the image forming unit 30.

[0020] The high-voltage output circuit 21 generates a high voltage to be supplied to a part used in the development process of the electrophotographic method. Specifically, the high-voltage output circuit 21 generates a necessary high voltage for a part to which a high voltage is applied, such as a developing roller or a charging roller, according to a control signal from the control board 10. Therefore, a plurality of high-voltage output circuits 21 are provided on the high-voltage circuit board 20 corresponding to each part to which a high voltage is applied.

[0021] Here, two high-voltage output circuits 21a and 21b are provided. Each high-voltage output circuit 21a and 21b generates a high voltage independently. The number of high-voltage output circuits 21 formed on the high-voltage circuit board 20 is not limited, and for example, two or more high-voltage output circuits 21 may be provided. Thus, in the image forming apparatus 100, high-voltage output circuits 21 that independently generate high voltages are provided within one board.

[0022] As the high-voltage output circuit 21, for example, a circuit that generates an AC output of high voltage by a step-up transformer or the like, or a circuit that generates a DC output of high voltage by a boost converter or the like is used. The specific configuration of the high-voltage output circuit 21 is not limited, and any circuit that generates a necessary high voltage can be used.

[0023] The image forming unit 30 is a mechanism that forms an image on a sheet by the electrophotographic method. Here, as mechanism components to which a high voltage is supplied from each high-voltage output circuit 21 of the high-voltage circuit board 20, a developing device 31 including a developing roller and a charging device 32 including a charging roller are illustrated. The above-described high-voltage output circuit 21a is a circuit that supplies a high voltage to the developing device 31, and the high-voltage output circuit 21b is a circuit that supplies a high voltage to the charging device 32.

[0024] Figure 2 is a schematic diagram showing an example of the circuit configuration of the high-voltage circuit board 20. Figure 2 schematically illustrates an example of the arrangement of each circuit component provided on the substrate surface 22 of the high-voltage circuit board 20. The high-voltage circuit board 20 is provided with various circuit components that constitute the high-voltage output circuits 21a and 21b described above. Here, the areas where the high-voltage output circuits 21a and 21b are formed are schematically shown by dotted lines.

[0025] The image forming apparatus 100 has a conductive material 23 provided in the space between the multiple high-voltage output circuits 21 and electrically grounded. The conductive material 23 is a conductive component, typically a metal part or the like. In this embodiment, the conductive material 23 is placed on the substrate surface 22 of the high-voltage circuit board 20. The conductive material 23 is also electrically grounded by being connected to, for example, the ground pattern (ground potential 1) of the high-voltage circuit board 20.

[0026] As described above, the conductive material 23 is provided in the space between the multiple high-voltage output circuits 21. Here, the space between the high-voltage output circuits 21 refers to, for example, the three-dimensional space above the substrate surface 22 formed between adjacent high-voltage output circuits 21. Therefore, the conductive material 23 can be said to be a conductive member arranged three-dimensionally above the substrate surface 22.

[0027] In the high-voltage circuit board 20 shown in Figure 2, two high-voltage output circuits 21a and 21b are arranged adjacent to each other. In this case, for example, a grounded conductive material 23 is placed in the three-dimensional space formed between the high-voltage output circuits 21a and 21b. The conductive material placed in this manner provides an electrostatic shielding effect between the high-voltage output circuits 21a and 21b.

[0028] Typically, the conductive material 23 used in the image forming apparatus 100 is a conductive member that has a predetermined function. For example, a conductive member that has a heat dissipation function for cooling circuit components or a support function for supporting a substrate is used as the conductive material 23. In other words, a conductive member that is originally provided in the image forming apparatus 100 is used as the conductive material 23. As a result, there is no need to newly provide additional members for shielding, for example, and thus a shielding effect can be achieved without increasing costs.

[0029] As shown in Figure 2, the high-voltage circuit board 20 is provided with various circuit components that constitute the high-voltage output circuit 21a and high-voltage output circuit 21b and other circuits, and these circuit components are appropriately connected by wiring patterns formed on the board surface 22. Here, as an example of circuit components, step-up transformers (T1 and T2), capacitors (C1, C2, C3, and C4), diode elements (D1, D2, D3, and D4), transistors Tr, and heat sink H are schematically shown.

[0030] The high-voltage output circuit 21a consists of a step-up transformer T1, capacitors C1 and C2, and diode elements D1 and D2. The high-voltage output circuit 21b consists of a step-up transformer T2, capacitors C3 and C4, and diode element D3. A heat sink H is connected to the transistor Tr.

[0031] The heat sink H is a metal component that dissipates the heat generated in the transistor Tr. As shown in Figure 2, the heat sink H is provided in the space between the multiple high-voltage output circuits 21 together with the transistor Tr and is connected to the ground potential 1. This heat sink H functions as a conductor 23. Thus, in this embodiment, the conductor 23 is the heat sink H provided on the high-voltage circuit board 20.

[0032] Figure 3 is a schematic circuit diagram illustrating the high-voltage portion of the high-voltage circuit board shown in Figure 2. The left side of Figure 3 shows a portion of the circuit including the step-up transformer T1 of the high-voltage output circuit 21a, while the right side shows a portion of the circuit including the step-up transformer T2 of the high-voltage output circuit 21b. Step-up transformers T1 and T2, for example, boost the AC voltage input to the primary side and output it from the secondary side. High-voltage output circuits 21a and 21b are constructed using this principle. Note that the circuit diagrams shown in Figure 3 do not represent the actual arrangement of elements in the circuit.

[0033] The step-up transformer T1 of the high-voltage output circuit 21a has a primary coil 11a and a secondary coil 12a. The primary coil 11a has a first input node 13a and a second input node 14a, and the secondary coil 12a has a first output node 15a and a second output node 16a. A capacitor C2, as shown in Figure 2, is connected in series to the first output node 15a of the secondary coil 12a. Here, the node of capacitor C2 opposite to the first output node 15a is referred to as the connection node 17a.

[0034] The step-up transformer T2 of the high-voltage output circuit 21b has a primary coil 11b and a secondary coil 12b. The primary coil 11b has a first input node 13b and a second input node 14b, and the secondary coil 12b has a first output node 15b and a second output node 16b. A capacitor C3, as shown in Figure 2, is connected in series to the first output node 15b of the secondary coil 12b. Here, the node of capacitor C3 opposite the first output node 15b is referred to as the connection node 17b.

[0035] For example, the high-voltage output circuit 21a is configured as a circuit that outputs a high voltage by appropriately connecting other elements to the connection node 17a and the second output node 16a. Similarly, the high-voltage output circuit 21b is configured as a circuit that outputs a high voltage by appropriately connecting other elements to the connection node 17b and the second output node 16b.

[0036] Thus, the high-voltage output circuits 21a and 21b have a circuit configuration in which capacitors (C1 and C2) are connected in series to the output side of the step-up transformers (T1 and T2). In this case, the part connecting the output node of the step-up transformer and the capacitors becomes a high-voltage point that generates a high voltage.

[0037] For example, in the high-voltage output circuit 21a, the point connecting the first output node 15a and capacitor C2 becomes the high-voltage point 18a. Similarly, in the high-voltage output circuit 21b, the point connecting the first output node 15b and capacitor C3 becomes the high-voltage point 18b.

[0038] In this embodiment, capacitors C2 and C3 are capacitor elements configured as leaded components. Here, a leaded component is a component on which a lead wire for connection is provided for the element body. Leaded components are mounted, for example, by soldering the lead wire to a connection pattern provided on the element substrate, and are positioned so as to protrude from the substrate surface of the element substrate. For this reason, leaded components are relatively taller than, for example, surface-mount type components. For example, in the high-voltage circuit board 20 shown in Figure 2, capacitors C2 and C3 are positioned so as to protrude from the substrate surface 22.

[0039] As described above, the high-voltage circuit board 20 according to this embodiment is provided with a pair of high-voltage output circuits 21a and 21b, each having a leaded component that is mounted on the substrate surface 22 of the high-voltage circuit board 20 and generates a high voltage, and which are arranged adjacent to each other. In other words, on the high-voltage circuit board 20, high-voltage points (high-voltage points 18a and high-voltage points 18b) that generate high voltage independently of each other are arranged to protrude from the substrate surface 22.

[0040] Specifically, capacitor C2 connected to the secondary side of step-up transformer T1 becomes a leaded component that generates high voltage in the high-voltage output circuit 21a. Similarly, capacitor C3 connected to the secondary side of step-up transformer T2 becomes a leaded component that generates high voltage in the high-voltage output circuit 21b.

[0041] As shown in Figure 2, in this embodiment, the conductive material 23 (heat sink H) described above is placed in the space between the leaded components (capacitors C2 and C3) provided in each of the pair of high-voltage output circuits 21a and 21b. In other words, the conductive material 23 is positioned to block the two high-voltage points 18a and 18b that protrude from the substrate surface 22.

[0042] [Interference from high-voltage output] Generally, when a high-voltage output is generated, interference from that output may occur depending on the circuit configuration. Below, we will explain high-voltage output interference with reference to Figures 4 and 5.

[0043] Figure 4 is a schematic diagram showing an example of the circuit configuration of a high-voltage circuit board 40, which is presented as a comparative example. Figure 5 is a schematic circuit diagram illustrating the high-voltage portion of the high-voltage circuit board 40 shown in Figure 4. The high-voltage circuit board 40 shown in Figures 4 and 5 has a circuit configured with the same function as the high-voltage circuit board 20 shown in Figures 3 and 4.

[0044] As shown in Figure 4, in the high-voltage circuit board 40 presented as a comparative example, the arrangement of the heat sink H and transistor Tr differs from the example shown in Figure 3, but the other circuit arrangements are the same. Here, the heat sink H and transistor Tr are located on the lower side of the high-voltage output circuit 21b in the diagram. Therefore, no conductive material is placed between the high-voltage output circuits 21a and 21b.

[0045] In the high-voltage output circuits 21a and 21b of the high-voltage circuit board 40, which are used as a comparative example, mutual interference of the high-voltage outputs generated by each circuit may occur. The cause of mutual interference of high-voltage outputs is capacitive coupling. In Figure 5, the capacitive coupling of high-voltage points 18a and 18b is shown using a hypothetical capacitive element 25. Capacitive coupling is a phenomenon in which energy is transferred between conductors due to the capacitance between conductors arranged across space from each other.

[0046] As a result, for example, the high voltage generated at high-voltage point 18a is superimposed on high-voltage point 18b via the capacitance created between it and high-voltage point 18b. This can cause the voltage at high-voltage point 18b to decrease or, conversely, increase. It is also conceivable that the voltage at high-voltage point 18a may change due to the transfer of energy between it and high-voltage point 18b.

[0047] Furthermore, since capacitor C2, which is the high-voltage point 18a, and capacitor C3, which is the high-voltage point 18b, are both leaded components, they are positioned protruding from the substrate surface 22. As a result, capacitive coupling is likely to occur between capacitor C2 and capacitor C3, which can be a major factor causing the mutual interference described above.

[0048] [High-voltage circuit board with conductive material] To suppress mutual interference between high-voltage outputs, it is effective to provide a GND between the high-voltage output circuits that cause interference. Therefore, in the high-voltage circuit board 20 according to this embodiment, as shown in Figure 2, a conductive material 23 (heat sink H) grounded to the space between the high-voltage output circuit 21a and the high-voltage output circuit 21b is provided. The conductive material 23 functions as a three-dimensional GND and functions as an electrostatic shielding member that blocks capacitive coupling through the space above the substrate surface 22. This makes it possible to easily suppress capacitive coupling between the high-voltage output circuit 21a and the high-voltage output circuit 21b.

[0049] Furthermore, the conductive material 23 (heat sink H) according to this embodiment is provided between high-voltage point 18a (capacitor C2) and high-voltage point 18b (capacitor C3). For example, the heat sink H is positioned perpendicular to the straight line connecting capacitor C2 and capacitor C3. In this case, as shown in Figure 3, high-voltage points 18a and 18b are coupled to the heat sink H, which is GND. As a result, direct coupling between high-voltage points 18a and 18b is prevented, and mutual interference of high-voltage outputs can be sufficiently suppressed.

[0050] Furthermore, instead of using a three-dimensional conductive material 23 on the substrate surface 22 to provide GND between the high-voltage output circuits 21, a ground pattern formed along the substrate surface 22 can also be considered. This method is effective, for example, when interference occurs between patterns, but its effectiveness decreases when interference occurs at a distance from the substrate surface 22, such as with leaded components.

[0051] Therefore, in this embodiment, by using a commonly used heat sink H as the conductive material 23, a three-dimensional electrostatic shield can be realized without additional components. For example, in the circuit shown in Figure 4, the heat sink H, which was placed solely for heat dissipation, can be repositioned between the high-voltage points 18a and 18b as shown in Figure 3, thereby enabling it to function as an electrostatic shield. This makes it possible to avoid interference from high-voltage output without increasing costs.

[0052] In the image forming apparatus 100 according to this embodiment, a grounded conductive material 23 is provided in the space between the multiple high-voltage output circuits 21 provided on the high-voltage circuit board 20. The conductive material 23 arranged in this manner inhibits, for example, capacitive coupling between the high-voltage output circuits 21. This makes it possible to suppress interference of high-voltage output with a simple configuration.

[0053] For example, to form an image using the electrophotographic method, it is necessary to supply a high voltage appropriate to each component to multiple components such as charging rollers, developing rollers, and transfer rollers. The high voltage supplied to each component is usually generated by a single high-voltage circuit board. Since a high-voltage circuit board generates multiple high voltages within a single board, depending on the distance and voltage, high-voltage outputs may interfere with adjacent high-voltage output circuits within the same high-voltage circuit board. This problem can become even more significant in small image forming apparatuses where the distance between adjacent circuits is small.

[0054] In contrast, in the image forming apparatus 100 according to this embodiment, a grounded conductive material 23 (heat sink H) is placed in the space between adjacent high-voltage output circuits 21a and 21b. As a result, the conductive material 23 functions as a three-dimensional electrostatic shield that shields the high-voltage output circuits 21a and 21b from each other. By simply placing the conductive material 23 in this manner, interference of high-voltage output can be easily suppressed.

[0055] Furthermore, a heat sink H, commonly used in circuits, is used as the conductive material 23. Therefore, it is possible to realize an electrostatic shield function between high-voltage output circuits without providing additional components. Also, even if the high-voltage circuit board 20 is miniaturized and the high-voltage points are closer together, the three-dimensional electrostatic shield (conductive material 23) makes it possible to reliably inhibit capacitive coupling at the high-voltage points. As a result, interference of high-voltage output can be sufficiently suppressed in the compact image forming apparatus 100.

[0056] <Other Embodiments> This technology is not limited to the embodiments described above, and various other embodiments can be realized.

[0057] In the above embodiment, a configuration was described in which a component (heat sink) provided on the high-voltage circuit board is used as a conductor. However, the invention is not limited to this, and for example, a component provided independently of the high-voltage circuit board may be used to constitute the conductor.

[0058] For example, the conductive material may be a grounded metal member that constitutes the main body of the image forming apparatus. Examples of metal members include sheet metal that makes up the main body of the image forming apparatus (structural members such as the housing cover and frame). For instance, when the high-voltage circuit board is mounted on the image forming apparatus, the metal member extending from the housing cover or frame is positioned in the space between the high-voltage output circuits. This makes it possible to easily suppress interference of the high-voltage output without changing the circuit configuration. Alternatively, a dedicated conductive metal member may be provided and electrically connected to the main body of the image forming apparatus.

[0059] In the above embodiment, a capacitor (lead component) was used as an example of a component that becomes a high-voltage point, but the component that becomes a high-voltage point may be other components depending on the configuration of the high-voltage output circuit, etc. In this case, a conductive material should be placed in the space between the components that become high voltage points in adjacent high-voltage output circuits. Furthermore, the number of conductive materials is not limited, and for example, multiple conductive materials may be provided so as to block high-voltage points that are close to each other.

[0060] The above mainly describes an image forming apparatus using an electronic printing method. However, the present invention is not limited to this and can be applied to any electronic device equipped with a high-voltage circuit board that generates multiple high voltages (for example, voltages higher than the voltage level of the power supply voltage or the voltage level of the control signal) on a single substrate.

[0061] It is also possible to combine at least two of the feature features of the present technology described above. In other words, the various feature features described in each embodiment may be combined arbitrarily, regardless of the specific embodiment. Furthermore, the various effects described above are merely examples and not limiting, and other effects may also be exhibited. [Explanation of Symbols]

[0062] H…Heat sink 1…Ground potential 10…Control board 18b…High-voltage locations 18a... High-voltage areas 20…High-voltage circuit board 21, 21a, 21b... High-voltage output circuits 22... Circuit board surface 23... Conductive materials 100…Image forming apparatus

Claims

1. A high-voltage circuit board having multiple high-voltage output circuits formed therein that generate high voltage supplied to parts used in the electrophotographic development process, A conductive material provided in the space between the plurality of high-voltage output circuits and electrically grounded An electronic device equipped with the following features.

2. The electronic device according to claim 1, The aforementioned conductive material is a conductive member that has a predetermined function in the electronic device. electronic equipment.

3. The electronic device according to claim 2, The conductive material is a heat sink provided on the high-voltage circuit board. electronic equipment.

4. The electronic device according to claim 2, The conductive material is a grounded metal member that constitutes the main body of the electronic device. electronic equipment.

5. An electronic device according to any one of claims 1 to 4, Each of the aforementioned multiple high-voltage output circuits includes a set of high-voltage output circuits arranged adjacent to each other, each having a leaded component that protrudes from the substrate surface of the high-voltage circuit board and generates a high voltage. The conductive material is provided in the space between the lead components provided in each of the set of high-voltage output circuits. electronic equipment.

6. The electronic device according to claim 5, The aforementioned leaded component is a capacitor connected to the secondary side of a step-up transformer. electronic equipment.

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