Image forming apparatus

Abstract

To reduce faulty cleaning of a transfer member.SOLUTION: In an image forming apparatus comprising a wire 154 connecting a jumper wire for electrification 150 and an electrifying roller 17 to each other, the wire 154 has a wire 154d located between a converter circuit for electrification 123 and a converter circuit for transfer 125 when seen in a y direction orthogonal to a surface of a printed circuit board 101.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] Conventional electrophotographic image forming devices use a roller transfer method in which a conductive roller is charged by applying a DC voltage and then rolled over the recording paper while applying an appropriate pressure, thereby transferring the charge to the recording paper. In this method, a high voltage of several hundred volts to approximately 6 kilovolts is applied to a conductive roller (hereinafter referred to as the transfer roller) to transfer the image to the recording paper. In this method, when no recording paper is inserted between the image carrier and the transfer roller, the transfer roller comes into direct contact with the image carrier. Therefore, if a jam occurs and the recording paper is not transported, the surface of the transfer roller becomes dirty with developer adhering to it. Furthermore, if developer remains on the image carrier between the recording paper and the next recording paper during initial operation or continuous printing, the surface of the transfer roller becomes dirty. Although the amount of developer adhering in this case is very small, prolonged use can lead to gradual deterioration of the dirt.

[0003] As such, contamination of the transfer roller with developer is unavoidable to some extent, making it necessary to clean the transfer roller. The transfer roller is cleaned by applying a voltage of the opposite polarity to that during transfer to the transfer roller when not transferring, and using electrostatic force to move the developer adhering to the surface of the transfer roller to the image carrier. Therefore, the transfer roller requires a high-voltage power supply device that can output a switchable positive or negative high voltage. Patent Document 1, for example, proposes a positive-negative switching high-voltage power supply device as a high-voltage power supply device that switches between positive and negative voltages. A schematic circuit diagram of a positive-negative switching high-voltage power supply device is shown in Figure 12.

[0004] 12, the secondary side of a charging power supply transformer 1414 that outputs a negative DC high voltage is connected to the transfer roller 7. As a result, when the charging power supply drive circuit 1404 is in the ON state and the transfer power supply drive circuit 1402 is in the OFF state, a negative DC high voltage is output from the charging power supply transformer 1414 to the transfer roller 7 via a resistor 1456. Therefore, by turning on the charging power supply drive circuit 1404 when no image is being formed on the photosensitive drum 11, a negative DC high voltage can be output to the transfer roller 7, thereby cleaning the transfer roller 7. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-206414 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a first circuit (charging power supply) that generates a negative high voltage and a second circuit (transfer power supply) that generates a positive high voltage are connected and the circuit is configured to output voltages of different polarities superimposed, noise generated in the first circuit may be coupled to the second circuit, reducing the negative DC voltage output. If the negative DC voltage output is reduced, poor cleaning of the transfer member may occur.

[0007] The present invention has been made under these circumstances, and has as its object to reduce the occurrence of poor cleaning of the transfer member. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0009] (1) An image forming apparatus comprising: a power supply circuit board having a first circuit having a first output section, generating a negative voltage and outputting it from the first output section to a first load; and a second circuit having a second output section, generating a positive voltage and outputting it from the second output section to a second load; and a conductive section connecting the first output section and the first load, wherein the conductive section has a first conductive section located between the first circuit and the second circuit when viewed in a first direction perpendicular to the surface of the power supply circuit board. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce defective cleaning of the transfer member. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of an image forming apparatus according to first and second embodiments; [Figure 2] Cross-sectional view of the image forming apparatus according to the first and second embodiments. [Figure 3] FIG. 10 is a perspective view illustrating the position of the circuit board in the first and second embodiments. [Figure 4] 1 is a perspective view of a circuit board and its peripheral members in Examples 1 and 2, and is a diagram for explaining electronic components on the circuit board. [Figure 5] Block diagram for explaining the function of the circuit board of Examples 1 and 2 [Figure 6] 1 is a perspective view of a contact portion provided at an end portion of a circuit board according to first and second embodiments; [Figure 7] Cross-sectional view of a contact portion provided at an end of a printed circuit board in Examples 1 and 2 [Figure 8] 1 is a view of the printed circuit board of Example 1 viewed from a direction perpendicular to the surface of the printed circuit board. [Figure 9] FIG. 1 is a perspective view of a circuit board seen from the rear of the main body of the first embodiment; [Figure 10] Circuit diagram showing coupling due to stray capacitance in Examples 1 and 2 [Figure 11] A top view of the circuit board for comparison with the wire shape of Example 2. [Figure 12] Conventional circuit diagram DETAILED DESCRIPTION OF THE INVENTION

[0012] <General high voltage power supply> FIG. 12 is a diagram showing a high-voltage power supply device, and also shows a photosensitive drum 11 as a rotating body, a charging roller 17 as a charging means, a developing roller 12, and a transfer roller 7 as a transferring means. In FIG. 12, a transfer power supply drive circuit 1402, a charging power supply drive circuit 1404, a developing DC power supply 1444, and a developing AC power supply 1480 are connected to a controller 1100. The controller 1100 controls the ON / OFF of the transfer power supply drive circuit 1402, the charging power supply drive circuit 1404, the developing DC power supply 1444, and the developing AC power supply 1480. The output of the charging power supply drive circuit 1404 is connected to the base of an npn-type transistor 1408. The collector terminal of the transistor 1408 is connected to a DC power supply 1410, and a signal from the controller 1100 controls the base current of the transistor 1408, thereby controlling the ON / OFF of the current flowing from the collector terminal to the emitter terminal. The emitter terminal of the transistor 1408 is connected to a primary winding 1418 of a charging power supply transformer 1414. The charging power supply transformer 1414 has a primary winding 1418 and a secondary winding 1422, and boosts the voltage on the primary side to output a high voltage from the secondary side. A diode 1426 is connected in series to the secondary winding 1422. A capacitor 1445 and a resistor 1438 are connected in parallel to the secondary winding 1422. When a signal to turn on the charging power supply drive circuit 1404 is input from the controller 1100, a negative DC high voltage is output from the secondary side of the transformer 1414. The secondary side of the transformer 1414 is connected to a charging roller 17 as a first load and a transfer roller 7 as a second load.

[0013] Next, the output of the transfer power supply driving circuit 1402, which is connected to the controller 1100, is connected to the base terminal of an NPN transistor 1406. The collector terminal of the transistor 1406 is connected to a DC power supply 1410, and a signal from the controller 1100 controls the base current of the transistor 1406, thereby controlling the ON / OFF of the current flowing from the collector terminal to the emitter terminal. The emitter terminal of the transistor 1406 is also connected to a primary winding 1416 of a transfer power supply transformer 1474. The transfer power supply transformer 1474 has a primary winding 1416 and a secondary winding 1420, and boosts the voltage on the primary side to output a high voltage. A diode 1424 is connected in series to the secondary winding 1420. The diode 1424 is connected so as to have the opposite polarity to the diode 1426 for the charging voltage. A capacitor 1470 and a resistor 1456 are connected in parallel to the secondary winding 1420. One end of the resistor 1456 and the forward side (cathode terminal) of the diode 1424 are connected to the transfer roller 7. Therefore, when a signal to turn on the transfer power supply driving circuit 1402 is input from the controller 1100, a positive DC high voltage is applied to the transfer roller 7.

[0014] Since the secondary side of the transformer 1414 for the charging power supply is also connected to the transfer roller 7, the charging voltage also serves as a transfer cleaning voltage for the transfer roller 7. When the charging power supply drive circuit 1404 is in the ON state and the transfer power supply drive circuit 1402 is in the OFF state, a negative high DC voltage is output from the transformer 1414 for the charging power supply to the transfer roller 7 via a resistor 1456. Therefore, by turning on the charging power supply drive circuit 1404 when no image is being formed on the photosensitive drum 11, a negative high DC voltage can be output to the transfer roller 7 to perform cleaning.

[0015] <Causes of poor cleaning> In circuits that generate high voltages using high-voltage transformers, AC voltages with peaks of several hundred volts to several kV are generated on the secondary side of the transformer as boosted voltages. Because stray capacitance exists between two conductors, when high AC voltages are generated, capacitive coupling occurs between nearby conductors, causing noise voltages from operating circuits to be transmitted to inactive circuits, affecting them. In a circuit configuration where the first circuit (charging power supply) that generates negative high voltage and the second circuit (transfer point) that generates positive high voltage are connected, as described above, and the output voltages of opposite polarities are superimposed, the pattern layout of the first and second circuits tends to be close to each other. As the pattern layout becomes closer, the coupling capacitance increases, strengthening the coupling between the two and increasing the noise voltage that is mixed in.

[0016] Furthermore, a rectifying and smoothing circuit is generally used in the circuit that generates the high DC voltage. When the high AC voltage generated by the first circuit is coupled as noise to the second circuit that generates a positive high DC voltage, the noise voltage is rectified and smoothed with a positive polarity, resulting in a positive high DC voltage being output from the second circuit. If a positive high DC voltage is output from the output of the second circuit, the positive high DC voltage is superimposed on the negative high DC voltage that should be applied to the transfer roller 7 during cleaning, reducing the negative DC voltage output.

[0017] The negative DC high voltage is used for the cleaning described above, and therefore it is necessary to output a voltage high enough to move the developer adhering to the surface of the transfer roller 7 to the photosensitive drum 11. However, if the necessary negative high voltage is insufficient due to the superposition of the positive DC high voltage caused by noise voltage, poor cleaning of the transfer roller 7 may occur, and image defects may occur due to the back side of the paper being soiled by toner adhesion. For the reasons mentioned above, in a power supply circuit board having a positive DC high voltage power supply (second circuit) and a negative DC high voltage (first circuit), image defects such as staining of the back of paper due to toner adhesion caused by poor cleaning of the transfer roller 7 can become particularly noticeable. [Example]

[0018] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0019] <Overall configuration of image forming apparatus> The overall configuration of the image forming apparatus 1 of the first embodiment will be described. In the following description, the height direction (opposite to the vertical direction) of the image forming apparatus 1 when the image forming apparatus 1 is installed on a horizontal surface is referred to as the Z direction. The direction that intersects with the Z direction and is parallel to the direction of the rotation axis of the photosensitive drum 11 (main scanning direction) described later is referred to as the X direction. The direction that intersects with the X and Z directions is referred to as the Y direction. The X, Y, and Z directions preferably intersect perpendicularly with each other. For convenience, the positive side in the X direction is referred to as the right side and the negative side is referred to as the left side; the positive side in the Y direction is referred to as the front side or front side and the negative side is referred to as the rear side or back side; and the positive side in the Z direction is referred to as the upper side and the negative side is referred to as the lower side.

[0020] FIG. 1 shows a perspective view of image forming apparatus 1, and FIG. 2 shows a cross-sectional view of image forming apparatus 1 cut along a plane perpendicular to the X direction (the rotational axis direction of photosensitive drum 11). In FIG. 1, image forming apparatus 1 has a feed cassette 4 that stores recording materials P, and an output tray 14 on which discharged recording materials P are stacked. When feed cassette 4 is inserted into a feed opening (not shown), the recording materials P stored in feed cassette 4 become ready to be fed into image forming apparatus 1. In addition, feed cassette 4 can be pulled out from the feed opening in the Y direction, allowing the user to replenish recording materials P. The recording materials P that have been fed from feed cassette 4 and on which images have been formed are discharged from output opening 15 in the discharge direction De (positive direction of the Y axis) shown in FIG. 1, and are stacked on output tray 14.

[0021] A front cover 70 is provided on a portion of the end face (part of the front face) of the image forming apparatus 1 downstream in the discharge direction De, and covers a circuit board 100, which will be described later. An exterior cover 71 is provided on a portion of the front face other than the portion where the front cover 70 is provided, as well as on the side and top faces of the image forming apparatus 1. The front cover 70, the exterior cover 71, and the discharge tray 14 described above together form a housing 72 of the image forming apparatus 1. Here, the housing 72 is a member that covers the entire image forming apparatus 1, and houses process components such as a scanner unit 50, which will be described later, inside. The above-mentioned feed port and discharge port 15 are openings formed in part of the housing 72, and the recording material P is inserted into the image forming apparatus 1 through the feed port and discharged to the outside of the image forming apparatus 1 through the discharge port 15.

[0022] The flow of an image forming operation on a recording material P will be described using the cross-sectional view of FIG. 2. When image information is sent to the image forming apparatus 1, the photosensitive drum 11, which is a rotating body, is rotated in the direction of arrow R at a predetermined peripheral speed (process speed) based on a print start signal. The scanner unit 50 irradiates the photosensitive drum 11 with laser light based on the input image information. The scanner unit 50 is a box-shaped unit that internally includes components such as a laser oscillator that outputs the laser light, a rotary polygonal mirror and lenses for irradiating the photosensitive drum 11 with the laser light, and a scanner motor for rotating the rotary polygonal mirror. The photosensitive drum 11 is pre-charged by a charging roller 17, and an electrostatic latent image is formed on the photosensitive drum 11 by irradiating it with laser light. Thereafter, the electrostatic latent image is developed with toner by a developing roller 12, forming a toner image on the photosensitive drum 11.

[0023] In parallel with the image formation process described above, recording materials P are fed from a feed cassette 4. A pickup roller 3, a feed roller 5a, and a pair of conveying rollers 5c are provided on the conveyance path of the image forming apparatus 1. The pickup roller 3 (feeding member) comes into contact with the uppermost recording material P stored in the feed cassette 4, and the roller itself rotates to feed the recording material P in the feed direction (the negative Y-axis direction). The feed roller 5a and the separation pad 5b that presses against it form a separation nip. If multiple sheets of recording materials P are fed into the separation nip due to the friction between the recording materials P, the feed roller 5a and the separation pad 5b separate the multiple sheets of recording materials P and feed only the uppermost one downstream.

[0024] The recording material P fed from the feeding cassette 4 is conveyed by a pair of conveying rollers 5c toward a transfer roller 7. A transfer voltage is applied to the transfer roller 7, so that the toner image formed on the photosensitive drum 11 is transferred onto the recording material P. The recording material P onto which the toner image has been transferred by the transfer roller 7 is heated and pressurized by a fixing device 9, so that the toner image is fixed onto the recording material P. The fixing device 9 is composed of a heating roller 9a incorporating a heater (not shown), and a pressure roller 9b that is urged toward the heating roller 9a. Then, the recording material P onto which the toner image has been fixed is discharged onto a discharge tray 14 by a pair of discharge rollers 10.

[0025] When an image is formed on both sides of the recording material P, the pair of discharge rollers 10 switches back the recording material P with the image formed on the first side, thereby guiding the recording material P to the double-sided conveying path 16. The recording material P guided to the double-sided conveying path 16 is conveyed again toward the transfer roller 7 by the pair of double-sided conveying rollers 5d. After an image is formed on the second side of the recording material P by the transfer roller 7, the recording material P is discharged outside the apparatus by the pair of discharge rollers 10. After the toner image is transferred to the recording material P, any toner remaining on the photosensitive drum 11 is cleaned by the cleaning unit 13.

[0026] As shown in Fig. 2, the image forming apparatus 1 has a circuit board 100. The circuit board 100 is composed of a printed circuit board 101 made of an insulating material as a power supply circuit board, and electronic component groups 111 and 121 soldered to the printed circuit board 101. The printed circuit board 101 is provided with conductive wiring, so that the electronic component groups 111 and 121 are electrically connected. The circuit board 100 is equipped with a converter circuit (not shown) that rectifies a voltage supplied from outside the image forming apparatus 1 and converts the voltage to obtain a predetermined voltage value required for the image formation process.

[0027] 2, the circuit board 100 is arranged so that the surface of the printed circuit board 101 on which the electronic component groups 111 and 121 are mounted intersects with the ejection direction De. Furthermore, the printed circuit board 101 is provided between the front cover 70 and the scanner unit 50 in the ejection direction De. The electronic component groups 111 and 121 are provided on the surface of the printed circuit board 101 facing the scanner unit 50.

[0028] <Circuit board layout> The arrangement of the circuit board 100 will now be described in detail. Fig. 3 is a perspective view of the image forming apparatus 1 for explaining the arrangement of the circuit board 100, and unlike Fig. 1, the front cover 70 and the exterior cover 71 are omitted. As shown in Fig. 3, the circuit board 100 is installed on the front side, and the scanner unit 50 and the drive motor 60 are provided further back (on the negative side in the Y direction) of the circuit board 100. Note that the scanner unit 50 and the drive motor 60 are shown in Fig. 3 by dotted lines because they are not actually visible.

[0029] 3, the image forming apparatus 1 has a right side plate frame 75 (first side plate frame), a left side plate frame 73 (second side plate frame), and a base frame 74. The right side plate frame 75 supports the right end of the photosensitive drum 11 in the X direction, and the left side plate frame 73 supports the left end of the photosensitive drum 11 in the X direction. The base frame 74 is provided on the bottom surface and supports the right side plate frame 75 and the left side plate frame 73 from below.

[0030] The circuit board 100 is supported by these frame members and is mounted on the image forming apparatus 1 with its plate surface approximately parallel to the XZ plane. The right and left side plates 75 and 73 have bent portions 75a and 73a formed at their Y-direction ends for reinforcement. The bent portion 75a is bent toward the positive side of the X direction so as to be approximately parallel to the XZ plane, while the bent portion 73a is bent toward the negative side of the X direction so as to be approximately parallel to the XZ plane. In other words, the bent portions 75a and 73a are bent so as to fit along the surface of the printed circuit board 101. By bending the side plates 75 and 73a toward the outside of the image forming apparatus 1 (away from the photosensitive drum 11 in the X direction), electronic components can be mounted on a larger area of the printed circuit board 101.

[0031] In this manner, the discharge direction De in which the recording material P is discharged in the direction (Y direction) perpendicular to the rotation axis direction of the photosensitive drum 11 as a rotating body that carries the toner image to be transferred onto the recording material P is defined as the front side of the image forming apparatus 1. In this case, the printed circuit board 101 is disposed on the front side of the image forming apparatus 1.

[0032] <Positional relationship between electronic components, scanner unit, and drive motor> Next, the positional relationship between the electronic component group 111, the scanner unit 50, and the drive motor 60 will be described in detail using FIG. 4(a). FIG. 4(a) is a perspective view of the circuit board 100 as viewed from the rear of the main body. The scanner unit 50 is located in an optimal position for irradiating the photosensitive drum 11 with laser light. The electronic component group 111, which is larger in the Y direction than the other components, is mounted to fit below the scanner unit 50 to efficiently utilize space. The drive motor 60 rotates the components for feeding and conveying the recording material P (such as the pickup roller 3, the feed roller 5a, and the conveying roller pair 5c) and the photosensitive drum 11. The drive motor 60 protrudes toward the negative side in the X direction, and the printed circuit board 101 is located on the front side of the main body relative to the drive motor 60. The electronic component group 111 is mounted away from the drive motor 60 to avoid interference with it. By arranging the electronic component group 111 in the above-described position, the image forming apparatus 1 can be made smaller. Reference numeral 115 denotes a power input unit.

[0033] As described above, the image forming apparatus 1 includes a front cover 70 (cover) provided on the front side, a scanner unit 50 that forms an electrostatic latent image on the photosensitive drum 11 (on the rotating body), and electronic component groups 111 and 121 mounted on a printed circuit board 101. The printed circuit board 101 is provided between the front cover 70 and the scanner unit 50 so as to intersect with the discharge direction De. The electronic component groups 111 and 121 are mounted on the surface of the printed circuit board 101 that faces the scanner unit 50.

[0034] <Circuit board configuration> Next, the configuration of the circuit board 100 will be described using Figure 4(b). Figure 4(b) is a rear view of the circuit board 100 as seen from the rear side of the main body. Figure 4(b) also illustrates the scanner unit 50 and drive motor 60 in addition to the circuit board 100. The circuit board 100 has a power supply input unit 115 that takes in AC voltage from an AC power supply, which is an external power source, a low-voltage power supply unit 110 that converts the AC voltage to DC voltage, and a high-voltage power supply unit 120 that supplies the high voltage required for image formation to each process component.

[0035] The low-voltage power supply unit 110 includes a group of electronic components 111 that are large in size in the Y direction, such as a low-voltage power supply transformer 112, a heat sink 113, and an electrolytic capacitor 114. The high-voltage power supply unit 120 includes a group of electronic components 121 that are large in size in the Y direction, such as a charging transformer 122 and a transfer transformer 124. As described above, in order to make the most of the space inside the image forming apparatus 1, all of the electronic components that are large in size in the Y direction are mounted on the printed circuit board 101 on the inner surface side of the image forming apparatus 1.

[0036] <Function of the circuit board> Next, the functions of the low-voltage power supply unit 110 and the high-voltage power supply unit 120 will be described with reference to Figures 4(b) and 5. Figure 5 is a block diagram showing the functions of the circuit board 100. First, the low-voltage power supply unit 110 takes in power from an AC voltage via a power supply input unit 115, and converts the AC voltage into a desired DC voltage (3.3V, 5V, 24V, etc.) using a converter circuit including an electrolytic capacitor 114 and a low-voltage power supply transformer 112. Furthermore, because power loss in the circuit components appears as heat, a heat sink 113 is provided to dissipate the heat.

[0037] The DC voltage output from the low-voltage power supply unit 110 is supplied to the high-voltage power supply unit 120, scanner unit 50, drive motor 60, engine controller 130, video controller 140, etc. via power distribution components such as patterns and harnesses on the printed circuit board 101. The engine controller 130 is responsible for overall control of various process components. The engine controller 130 includes a CPU (not shown), a RAM (not shown) used for calculations and temporary storage of data necessary for controlling the image forming apparatus 1, and a ROM (not shown) for storing programs and various data for controlling the image forming apparatus 1. The engine controller 130 may be provided on a board separate from or on the same board as the circuit board 100. The video controller 140 communicates with external devices such as a personal computer to receive print data and notifies the engine controller 130 of the results of analyzing the print data. The high voltage generated by the high-voltage power supply unit 120 is supplied to the charging roller 17, the developing roller 12, and the transfer roller 7.

[0038] <Configuration of electrical contacts> Next, the configuration of the contacts and the function of the high-voltage power supply unit 120 will be described with reference to Figures 6 and 7. Figure 6 shows a perspective view of the contact unit provided at the end of the printed circuit board 101, Figure 7(a) shows a cross-sectional view of the charging contact unit provided at the end of the printed circuit board 101, and Figure 7(b) shows a cross-sectional view of the transfer contact unit provided at the end of the printed circuit board 101.

[0039] The high-voltage power supply unit 120 has a converter circuit that converts the voltage (for example, 24 V) supplied from the low-voltage power supply unit 110 into a high voltage required for the image formation process, such as charging, developing, and transferring. A charging converter circuit 123 (see FIG. 8) serving as a first circuit including a charging transformer 122 converts the voltage supplied from the low-voltage power supply unit 110 into a high voltage for charging, and the high voltage is supplied to a charging jumper wire 150 serving as a first output unit.

[0040] The charging jumper wire 150 is arranged across a slit 153 (indicated by a dashed line in FIG. 7(a)), which is a through-hole that penetrates the component side 101a and the solder side 101b of the printed circuit board 101. The charging contact spring 151 is designed to allow the arm portion 152 to fit into this slit 153, and when the arm portion 152 fits in, the charging jumper wire 150 and the arm portion 152 come into contact. The charging contact spring 151 is shaped like a torsion coil spring. The arm portion 152 is designed so that a force acts in the direction of the charging jumper wire 150, so pressure 155 is generated at the contact point between the arm portion 152 and the charging jumper wire 150, resulting in a stable electrical contact.

[0041] A transfer converter circuit 125 (see FIG. 8) serving as a second circuit including a transfer transformer 124 converts the voltage supplied from the low-voltage power supply unit 110 into a high voltage for transfer, and the high voltage is supplied to a transfer jumper wire 156 serving as a second output unit. The transfer jumper wire 156 is provided across a slit 159 (indicated by a dashed line in FIG. 7(b)), which is a through-hole that penetrates the component surface 101a and the solder surface 101b of the printed circuit board 101. The transfer jumper wire 156 is configured to allow an arm portion 158 of a transfer contact spring 157 to fit into this slit 159, and when the arm portion 158 fits into the slit, the transfer jumper wire 156 and the arm portion 158 come into contact. The transfer contact spring 157 is in the form of a torsion coil spring. Because arm portion 158 is set so that a force acts in the direction of transfer jumper wire 156, pressure 161 is generated at the contact point between arm portion 158 and transfer jumper wire 156, resulting in a stable electrical contact. Note that because the secondary side of transformer 122 is also connected to transfer roller 7 (see FIG. 9), the charging voltage is also the transfer cleaning voltage. In this way, transfer jumper wire 156 can output a negative voltage generated by charging converter circuit 123 to transfer roller 7.

[0042] <Wire and guide configuration> Next, the configuration of the other arm portion 154 and guide of the charging contact spring 151 will be described using Figures 8, 9, and 10. The arm portion 154 is a conductive portion that connects the charging jumper wire 150 and the charging roller 17. In Example 1, the conductive portion is implemented as a wire as an example, and will hereinafter be referred to as the wire 154. The charging contact spring 151 has two arms (see Figure 7(a)), and the arm portion 152 on one side is configured to be able to come into contact with the charging jumper wire 150, as described above. In other words, the wire 154 is one end of the charging contact spring 151, which is a torsion coil spring, and the other end of the charging contact spring 151 is connected to the charging jumper wire 150.

[0043] The wire 154 is supported by a guide member 200. The guide member 200 includes a first guide portion 201 and a second guide portion 202. When viewed in the y direction, the wire 154 has a wire 154d as a first conductive portion located between the charging converter circuit 123 and the transfer converter circuit 125. The wire 154 has a wire 154e as a second conductive portion connected to the wire 154d and extending toward the charging roller 17. As shown in FIG. 9, the first guide portion 201 supports the wire 154d, and the second guide portion 202 supports the wire 154e.

[0044] As shown in FIG. 11 , which will be described later, the first guide portion 201 is supported by a support member 129 attached to the substrate 101. The support member 129 has, for example, a rectangular shape with a hollow interior, and is configured so that the first guide portion 201 passes through the hollow portion. A plurality of support members 129 may be provided according to the length of the first guide portion 201. Note that the surface 201d shown in FIG. 9 may be directly bonded to the substrate 101. The wire 154 is supported by the surface 201e of the first guide portion 201 and the surface 202d of the second guide portion 202. The position of the wire 154 from the substrate 101 in the Y direction (height from the substrate 101) is configured as follows: Here, the length in the Y direction of the capacitor 470 (first capacitor) of the circuit 125 and the capacitor 1445 (second capacitor) of the circuit 123 is referred to as the height from the substrate 101. In order to prevent the capacitors 470 and 1445 from being affected by the generated noise, the position of the wire 154 in the Y direction is set to a position equal to or lower than the height of the capacitors 470 and 1445. As shown in Figures 11(a) and 11(b), if the height from the printed circuit board 101 to the capacitors 470 and 1445 is defined as height H1 and the height from the printed circuit board 101 to the wire 154 (154d) is defined as height H2, then height H2 is lower than height H1 (H1>H2).

[0045] The wire 154 is supported by a first guide portion 201 extending along the surface (component surface 101a) of the printed circuit board 101 and a second guide portion 202 extending away from the surface (component surface 101a) of the printed circuit board 101 toward the charging roller 17, and is connected to the charging roller 17. The first guide portion 201 and the second guide portion 202 are, for example, molded guides. FIG. 8 shows the printed circuit board 101 as viewed from a direction perpendicular to the surface of the printed circuit board 101 (normal direction). At this time, the first guide portion 201 is located between the charging converter circuit 123 and the transfer converter circuit 125.

[0046] As shown in FIG. 9 , the first guide portion 201 is cylindrical and has a first end portion 201a and a second end portion 201b that is farther from the charging jumper wire 150 than the first end portion 201a. The second guide portion 202 is cylindrical and has a third end portion 202a and a fourth end portion 202b that is farther from the first guide portion 201 than the third end portion 202a. The first end portion 201a and the fourth end portion 202b have openings 201c and 202c, respectively. The second end portion 201b and the third end portion 202a are connected to each other. The wire 154 is supported within the cylindrical shapes of the first guide portion 201 and the second guide portion 202.

[0047] FIG. 9 is a perspective view of the circuit board 100 as viewed from the rear of the main body. In addition to the circuit board 100, FIG. 9 also illustrates the wire 154, the first guide portion 201, and the second guide portion 202. In the first embodiment, the first guide portion 201 and the second guide portion 202 are cylindrical with a rectangular cross section. The first guide portion 201 and the second guide portion 202 each have an opening 201c or 202c on only one side, and the joints (second end 201b and third end 202a) of the first guide portion 201 and the second guide portion 202 are integrated without any gaps. The wire 154 enters through the opening 201c of the first guide portion 201, passes through the interiors of the first guide portion 201 and the second guide portion 202, and exits through the opening 202c of the second guide portion 202.

[0048] When the arm portion 152 comes into contact with the charging jumper wire 150 and functions as an electrical contact, the high voltage generated by the charging converter circuit 123 can be supplied to the charging roller 17 via the charging jumper wire 150, charging contact spring 151, and wire 154. At this time, a high-voltage AC current is generated on the pattern of the charging converter circuit 123. Electrostatic capacitance always exists between two unshielded conductors, and, for example, as shown in FIG. 10, noise is transmitted from the charging converter circuit 123 to the transfer converter circuit 125 due to coupling capacitance 1490 between the patterns. The noise voltage is rectified and smoothed by diode 424 and capacitor 470 and then superimposed as a transfer output. Note that other components in FIG. 10 are the same as those in FIG. 12, so the same reference numerals are used and their description is omitted.

[0049] When the first guide portion 201 is positioned between the charge converter circuit 123 and the transfer converter circuit 125, the wire 154 supported by the first guide portion 201 acts as a shield between the charge converter circuit 123 and the transfer converter circuit 125. The presence of the shield suppresses capacitive coupling and reduces voltage interference as noise in the transfer converter circuit 125. As a result, the negative high DC voltage used for cleaning is output as expected, reducing the likelihood of poor cleaning of the transfer roller 7 and suppressing image defects caused by backside contamination of the recording material P due to toner adhesion. Furthermore, by providing the first guide portion 201 and the second guide portion 202 between the charge converter circuit 123 and the transfer converter circuit 125, the creepage distance between the charge converter circuit 123 and the transfer converter circuit 125 can be secured, i.e., increased.

[0050] As described above, in the first embodiment, the wire 154 that supplies high voltage to the charging roller 17 is supported by the first guide portion 201 that extends along the printed circuit board 101 and the second guide portion 202 that extends away from the surface of the printed circuit board 101 toward the charging roller 17. By using the wire 154 for supplying high voltage to shield the pattern that emits noise from the pattern that receives noise and to suppress capacitive coupling, it is possible to suppress image defects caused by staining of the back side of the recording material P due to toner adhesion and to reduce components required to prevent capacitive coupling.

[0051] Note that the image forming apparatus 1, circuit configuration, and main body configuration described in the first embodiment are merely examples, and are not intended to limit the scope of the present invention to those. The shapes of the first guide portion 201 and the second guide portion 202 and the positional relationship between the high-voltage supply wire 154 and the first guide portion 201 and the second guide portion 202 are not limited to these configurations. The first guide portion 201 and the second guide portion 202 may have any shape, and may be independent rather than integrated.

[0052] As described above, according to the first embodiment, it is possible to reduce the cleaning failure of the transfer member. [Example]

[0053] In Example 1, wire 154, which supplies high voltage to charging roller 17, is supported by a first guide portion 201 extending along printed circuit board 101 and a second guide portion 202 extending away from the surface of circuit board 101 toward charging roller 17. Wire 154 described in Example 1 is cylindrical (with a circular cross section), and its cross section remains approximately circular and has approximately the same diameter no matter where in the path from charging jumper wire 150 to charging roller 17 the wire 154 is located.

[0054] When using a shield to suppress capacitive coupling between the charging converter circuit 123 and the transfer converter circuit 125, the larger the shielded area, the greater the effect. Therefore, in Example 2, the shape of the wire 154 is changed within the range where the wire 154 is supported by the first guide portion 201. The shape of the wire 154 is changed midway along the path that supplies high voltage from the charging jumper wire 150 to the charging roller 17, thereby increasing the area that shields the pattern that is emitting noise and the pattern that is affected by the noise. This makes it possible to more effectively suppress capacitive coupling, and therefore a greater effect can be expected.

[0055] The overall configuration of the image forming apparatus 1, the arrangement of the circuit board 100, the positional relationship between the electronic component groups 111, 121 and the scanner unit 50 and drive motor 60, the configuration of the circuit board, the function of the circuit board, and the configuration of the electrical contacts are the same as those in Example 1, and therefore will not be described.

[0056] <Wire and guide configuration> Fig. 11(a) is a view of the circuit board 100 shown in Example 1 as seen from above. The shape of the wire 154 is the same as described above whether it is in a position supported by the first guide portion 201, a position supported by the second guide portion 202, or a position not supported by the guide member 200. Fig. 11(b) is a view showing that the shape of the wire 154 at the position supported by the first guide portion 201 (first position) is different from the shape of the wire 154 at a position other than the position supported by the first guide portion 201 (second position). That is, the shape of the wire 154 is different between the portion 154a supported by the first guide portion 201 and the portion 154b other than the portion 154a.

[0057] 11(c), in the configuration of Example 2, the shape of the wire 154 is an elliptical cylinder (elliptical cross section) with a long diameter in the Y-axis direction of a portion 154a at a position supported by the first guide portion 201. The first guide portion 201 is located between the charging converter circuit 123 and the transfer converter circuit 125. Therefore, when the wire 154 (portion 154a) becomes large in the Y-axis direction, the area shielding the charging converter circuit 123 and the transfer converter circuit 125 becomes large, and capacitive coupling can be suppressed more effectively.

[0058] Note that the configuration described in Example 2 is merely an example and is not intended to be limiting. As long as the shape of the wire 154 can effectively suppress capacitive coupling, the shape of the portion 154a is not limited to an elliptical cross section and may be other shapes. For example, as shown in FIG. 11(d), the wire 154 may have a rectangular parallelepiped shape (rectangular cross section) with short sides in the Z-axis direction and long sides in the Y-axis direction at the portion 154c where the wire 154 is supported by the first guide portion 201.

[0059] Thus, the cross-sectional shape of wire 154 perpendicular to the extension direction in which wire 154 extends is different between the cross-sectional shape at the first position where wire 154 is supported by first guide portion 201 and the cross-sectional shape at the second position where wire 154 is not supported by first guide portion 201. Specifically, the length of wire 154 in the direction perpendicular to the extension direction and the vertical direction (Y direction) at the first position is longer than the length of wire 154 in the direction perpendicular to the extension direction and the vertical direction at the second position.

[0060] As described above, according to the second embodiment, it is possible to reduce the cleaning failure of the transfer member.

[0061] The disclosure of this embodiment includes the following configuration. (Configuration 1) a power supply circuit board including: a first circuit having a first output section, generating a negative voltage and outputting it from the first output section to a first load; and a second circuit having a second output section, generating a positive voltage and outputting it from the second output section to a second load; a conductive part connecting the first output part and the first load; In an image forming apparatus comprising: The image forming apparatus is characterized in that the conductive portion has a first conductive portion located between the first circuit and the second circuit when viewed in a first direction perpendicular to the surface of the power supply circuit board. (Configuration 2) a guide member for supporting the conductive portion; the conductive portion has a second conductive portion connected to the first conductive portion and extending toward the first load; 2. The image forming apparatus according to claim 1, wherein the guide member includes a first guide member that supports the first conductive portion and a second guide member that supports the second conductive portion. (Configuration 3) the first circuit includes a first capacitor; the second circuit includes a second capacitor; The image forming apparatus of configuration 1 or 2, characterized in that, when viewed in a direction parallel to the surface, the height of the first conductive portion from the surface in the first direction is lower than the height of the first capacitor from the surface in the first direction or the height of the second capacitor from the surface in the first direction. (Configuration 4) The image forming apparatus according to any one of configurations 1 to 3, wherein the conductive portion is disposed on the same side as the surface of the power supply circuit board on which the first capacitor and the second capacitor are mounted. (Configuration 5) 5. The image forming apparatus according to any one of configurations 1 to 4, wherein the guide member is located between the first circuit and the second circuit, and increases a creepage distance between the first circuit and the second circuit. (Configuration 6) 6. The image forming apparatus according to any one of configurations 1 to 5, wherein the second output unit is capable of outputting the negative voltage generated by the first circuit to the second load. (Configuration 7) 7. The image forming apparatus according to any one of configurations 1 to 6, wherein the conductive portion is one end side of a torsion coil spring, and the other end side of the torsion coil spring is connected to the first output portion. (Configuration 8) a rotating body that carries a toner image to be transferred onto a recording material; When the ejection direction in which the recording material is ejected in a direction perpendicular to the rotation axis of the rotating body and the vertical direction is set to the front side of the image forming apparatus, 8. The image forming apparatus according to any one of configurations 1 to 7, wherein the power supply circuit board is disposed on the front side of the image forming apparatus. (Configuration 9) a cover provided on the front side; a scanner unit that forms an electrostatic latent image on the rotating body; a group of electronic components mounted on the power supply circuit board; Equipped with the power supply circuit board is provided between the cover and the scanner unit so as to intersect with the ejection direction; 9. The image forming apparatus according to configuration 8, wherein the electronic components are mounted on a surface facing the scanner unit. (Configuration 10) The image forming apparatus according to any one of configurations 2 to 9, wherein the cross-sectional shape of the conductive portion perpendicular to the extension direction of the conductive portion is different between a first position where the conductive portion is supported by the first guide member and a second position where the conductive portion is not supported by the first guide member. (Configuration 11) The image forming apparatus of configuration 10, wherein the length of the conductive portion in a direction perpendicular to the extension direction and the vertical direction at the first position is longer than the length of the conductive portion in a direction perpendicular to the extension direction and the vertical direction at the second position. (Configuration 12) a rotating body that carries a toner image to be transferred onto a recording material; charging means for charging the rotating body; a transfer means for transferring the toner image carried on the rotating body onto a recording material; Equipped with the first load is the charging means, 12. The image forming apparatus according to any one of configurations 1 to 11, wherein the second load is the transfer means. [Explanation of symbols]

[0062] 101 Printed Circuit Board 123 Charge converter circuit 125 Transfer converter circuit 154 Wire 200 Guide member 201 First Guide Section 202 Second guide section

Claims

1. a power supply circuit board including: a first circuit having a first output section, generating a negative voltage and outputting it from the first output section to a first load; and a second circuit having a second output section, generating a positive voltage and outputting it from the second output section to a second load; a conductive part connecting the first output part and the first load; In an image forming apparatus comprising: an image forming apparatus characterized in that the conductive portion has a first conductive portion located between the first circuit and the second circuit when viewed in a first direction perpendicular to the surface of the power supply circuit board;

2. a guide member for supporting the conductive portion; the conductive portion has a second conductive portion connected to the first conductive portion and extending toward the first load; 2. The image forming apparatus according to claim 1, wherein the guide member includes a first guide member that supports the first conductive portion and a second guide member that supports the second conductive portion.

3. the first circuit includes a first capacitor; the second circuit includes a second capacitor; 2. The image forming apparatus of claim 1, wherein, when viewed in a direction parallel to the surface, the height of the first conductive portion from the surface in the first direction is lower than the height of the first capacitor from the surface in the first direction or the height of the second capacitor from the surface in the first direction.

4. 4. The image forming apparatus according to claim 3, wherein the conductive portion is disposed on the same surface of the power supply circuit board as the surface on which the first capacitor and the second capacitor are mounted.

5. 3. The image forming apparatus according to claim 2, wherein the guide member is positioned between the first circuit and the second circuit, and increases a creepage distance between the first circuit and the second circuit.

6. 2. The image forming apparatus according to claim 1, wherein the second output section is capable of outputting the negative voltage generated by the first circuit to the second load.

7. 2. The image forming apparatus according to claim 1, wherein the conductive portion is one end of a torsion coil spring, and the other end of the torsion coil spring is connected to the first output portion.

8. a rotating body that carries a toner image to be transferred onto a recording material; When the ejection direction in which the recording material is ejected in a direction perpendicular to the rotation axis of the rotating body and the vertical direction is set to the front side of the image forming apparatus, 2. The image forming apparatus according to claim 1, wherein the power supply circuit board is disposed on the front side of the image forming apparatus.

9. a cover provided on the front side; a scanner unit that forms an electrostatic latent image on the rotating body; a group of electronic components mounted on the power supply circuit board; Equipped with the power supply circuit board is provided between the cover and the scanner unit so as to intersect with the ejection direction; 9. The image forming apparatus according to claim 8, wherein the electronic components are mounted on a surface facing the scanner unit.

10. 3. The image forming apparatus according to claim 2, wherein the cross-sectional shape of the conductive portion perpendicular to the extension direction of the conductive portion is different between a first position where the conductive portion is supported by the first guide member and a second position where the conductive portion is not supported by the first guide member.

11. 11. The image forming apparatus according to claim 10, wherein the length of the conductive portion in a direction perpendicular to the extension direction and the vertical direction at the first position is longer than the length of the conductive portion in a direction perpendicular to the extension direction and the vertical direction at the second position.

12. a rotating body that carries a toner image to be transferred onto a recording material; charging means for charging the rotating body; a transfer means for transferring the toner image carried on the rotating body onto a recording material; Equipped with the first load is the charging means, 2. The image forming apparatus according to claim 1, wherein the second load is the transfer means.

Images