Circuit boards, image forming apparatus

Abstract

To solve the problem in which: an IC cannot be replaced with another IC replaceable with the IC.SOLUTION: A circuit board 300 has an IC 10 and an IC 20 exclusively mounted thereon and is used for achieving a predetermined function, and the circuit board has: a first conductor pattern formed to electrically connect an electrical part component 3031 including the IC 10 mounted on one face of the circuit board 300 and a common part; vias electrically connected with the first conductor pattern; and a second conductor pattern formed to electrically connect an electrical part component 3032 including the IC 20 mounted on the other face of the circuit board 300 and the common part mounted on one face through the vias.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a printer, a copier, or a multifunction peripheral that has a circuit board on which electric components for operating built-in components such as an actuator are mounted. Background Art

[0002] An image forming apparatus includes a plurality of control circuit boards for controlling a plurality of actuators provided for image formation. A plurality of electric components are mounted on the control circuit board, such as electric components for performing logical operations, electric components for performing drive control, and electric components for generating a power supply voltage. Each electric component constitutes an electric component component that implements a predetermined function including peripheral electric components. For example, an electric component component is constituted by an integrated circuit (IC) and peripheral electric components such as resistors, capacitors, and inductors connected to input / output terminals of the IC.

[0003] A circuit board is manufactured by procuring and mounting a large number of electric components. However, for various reasons such as distribution, environment, and accidents, it may become difficult to obtain electric components. For example, supply shortages of ICs have become a problem in recent years. In order to avoid such a situation, alternative replaceable components having the same function and the same or similar shape and specifications are investigated in advance for each electric component, and when a component procurement problem occurs, the alternative replaceable components are procured. The manufacturing of the circuit board is continued using the alternative replaceable components.

[0004] An image forming apparatus prints an image onto paper through multiple processes, including paper transport, image formation, image transfer to paper, and image fixing to paper. To achieve this, the image forming apparatus needs to control a wide variety of actuators, such as optical sensors, temperature sensors, motors, and solenoids. The control circuit board mounted on the image forming apparatus incorporates multiple ICs for actuator control. For example, a motor driver board for driving a motor has an IC for generating a motor drive signal based on a control signal input from a controller in order to properly control the motor (Patent Document 1). Furthermore, multiple control circuit boards are provided within the image forming apparatus.

[0005] In control circuit boards, the required voltage may differ depending on the connected actuator. Therefore, multiple voltage-generating electrical components are mounted on the circuit board to produce different voltage values. In such a configuration, multiple power supply voltages with different voltage values ​​are generated within the control circuit board. DC-DC converter ICs, which have low heat loss, are widely used as voltage-generating electrical components (Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-6639 [Patent Document 2] Japanese Patent Publication No. 2021-164356 [Overview of the project] [Problems that the invention aims to solve]

[0007] DC-DC converter ICs and motor driver ICs often require peripheral components for proper operation. Furthermore, the terminal functions and electrical specifications of DC-DC converter ICs and motor driver ICs almost always differ from one IC to another. Therefore, simply replacing one IC with another may not guarantee proper operation due to differences in required peripheral components, terminal functions, voltage values, etc.

[0008] Therefore, a circuit board designed to implement a specific function is equipped with electrical component parts consisting of an IC and peripheral components (electrical parts) that complement the IC's function. Furthermore, the wiring (conductor patterns) on the circuit board are often specific to the IC. Replacing one IC with another requires corresponding peripheral components and wiring (conductor patterns) for the replacement IC. In other words, replacing an IC requires a redesign of the circuit board. Consequently, it is not easy to simply replace an IC in a circuit board designed to implement a specific function.

[0009] In view of the above-mentioned problems, the present invention aims to provide a circuit board that allows for easy replacement of an IC with another IC that can be used as a substitute. [Means for solving the problem]

[0010] A circuit board according to one embodiment of the present invention is a first integrated circuit or Different from the above-mentioned integrated circuit Second integrated circuit Either one of them exclusively A circuit board for an image forming apparatus, comprising: an electrical component provided on a first surface of the circuit board; a first mounting portion provided on the first surface of the circuit board and configured to allow the attachment of terminals of a first integrated circuit; a first conductor pattern formed on the first surface and constituting at least a part of a first wiring that connects the first mounting portion and the electrical component; a second mounting portion provided on a second surface of the circuit board opposite to the first surface and configured to allow the attachment of terminals of a second integrated circuit; a second conductor pattern formed on the second surface and constituting a part of a second wiring that connects the second mounting portion and the electrical component; and a via that penetrates the circuit board and constitutes another part of the second wiring. Another embodiment of the present invention is an image forming apparatus for forming an image on paper, comprising a first integrated circuit or Different from the above-mentioned integrated circuit Second integrated circuit Either one of them exclusivelyThe present invention includes a circuit board and a conversion means for converting the value of a voltage input to the circuit board, wherein the circuit board comprises an electrical component provided on a first surface of the circuit board, a first mounting portion provided on the first surface of the circuit board and configured to allow the attachment of terminals of a first integrated circuit, a first conductor pattern formed on the first surface and constituting at least a part of a first wiring that connects the first mounting portion and the electrical component, a second mounting portion provided on a second surface of the circuit board opposite to the first surface and configured to allow the attachment of terminals of a second integrated circuit, a second conductor pattern formed on the second surface and constituting a part of a second wiring that connects the second mounting portion and the electrical component, and vias that penetrate the circuit board and constitute another part of the second wiring. An image forming apparatus according to another embodiment of the present invention includes a rotating body that rotates to form an image on paper, a drive source, and a first integrated circuit or Different from the above-mentioned integrated circuit Second integrated circuit Either one of them exclusively An image forming apparatus comprising a circuit board provided for controlling the drive source to rotate the rotating body, wherein the circuit board comprises an electrical component provided on a first surface of the circuit board; a first mounting portion provided on the first surface of the circuit board and configured to allow the attachment of terminals of a first integrated circuit; a first conductor pattern formed on the first surface and constituting at least a part of a first wiring that connects the first mounting portion and the electrical component; a second mounting portion provided on a second surface of the circuit board opposite to the first surface and configured to allow the attachment of terminals of a second integrated circuit; a second conductor pattern formed on the second surface and constituting a part of a second wiring that connects the second mounting portion and the electrical component; and vias that penetrate the circuit board and constituting another part of the second wiring. [Effects of the Invention]

[0011] According to the present invention, an IC can be easily replaced with another IC that is interchangeable with it. [Brief explanation of the drawing]

[0012] [Figure 1] System configuration diagram of an image forming apparatus. [Figure 2] Configuration diagram of an image forming apparatus. [Figure 3] Functional block diagram of a circuit board. [Figure 4] Circuit diagram of a DCDC converter. [Figure 5] Explanatory diagram of a DCDC converter on a circuit board. Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration and circuit of the apparatus described in the present embodiment are merely examples for explaining the content of the proposal, and are not limited to the content described herein.

[0014] (Configuration of Image Forming Apparatus) FIG. 1 is a system configuration diagram of an image forming apparatus including the circuit board according to the present embodiment. It goes without saying that, unless otherwise specified, the image forming apparatus 100 may be a system configured by a plurality of apparatuses connected via a network as long as the functions of the image forming apparatus 100 can be implemented.

[0015] The image forming apparatus 100 of the present embodiment is communicably connected to a host computer 101 via a network 105. The network 105 is constituted by communication lines such as a LAN (Local Area Network), a WAN (Wide Area Network), and a public line. A plurality of the image forming apparatuses 100 and a plurality of the host computers 101 may be connected to the network 105, respectively. The host computer 101 generates a print job and transmits the print job to the image forming apparatus 100 via the network 105.

[0016] An image forming apparatus 100 includes a controller board 110, a storage 115, a paper feeding unit 140, a printer engine 150, and an operation panel 180. The controller board 110, the storage 115, the paper feeding unit 140, the printer engine 150, and the operation panel 180 are communicatively connected to each other via a system bus 116.

[0017] The controller board 110 includes an I / O control unit 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and a CPU (Central Processing Unit) 114. The I / O control unit 111, the ROM 112, the RAM 113, and the CPU are mounted on a circuit board. The controller board 110 functions as a main control unit of the image forming apparatus 100, and controls the overall operation of the image forming apparatus 100. The circuit board is a multilayer printed circuit board.

[0018] The I / O control unit 111 controls communication with an external device such as a host computer 101 via a network 105. The CPU 114 executes computer programs stored in the ROM 112 and the storage 115, thereby controlling operations such as image forming processing performed by the image forming apparatus 100. The RAM 113 provides a work area for the CPU 114 to execute processing, and stores temporary data and the like. The storage 115 stores large-capacity data such as image data and print data temporarily or long-term. For example, the storage 115 stores image data for generating an adjustment image for adjusting image forming conditions. A control program and an operating system executed by the CPU 114 are stored in the ROM 112 and the storage 115.

[0019] The control panel 180 is a user interface equipped with input and output interfaces. The input interface is, for example, a key button or a touch panel. The output interface is, for example, a display or a speaker. The control panel 180 receives instructions and other information from the user and inputs them to the CPU 114. The CPU 114 controls the operation of the image forming apparatus 100 according to the instructions. The control panel 180 also displays the status of the image forming apparatus 100 and various setting screens according to instructions from the CPU 114.

[0020] The paper feeding unit 140 includes a paper feeding device consisting of one or more paper feeding stages, and an entire transport unit that transports paper from the paper feeding stages to the paper discharge unit. The paper feeding unit 140 feeds paper one sheet at a time from the paper feeding stages in response to instructions from the CPU 114.

[0021] The printer engine 150 comprises an image forming unit 152, a print position control unit 153, an image position detection unit 154, a fuser unit 260, and an image reading unit 290. The image forming unit 152 forms an image (toner image) on the paper fed by the paper feeding unit 140. The fuser unit 260 fixes the image (toner image) to the paper. The image reading unit 290 reads an adjustment image printed on the image. The image position detection unit 154 detects the image position on the paper based on the reading result of the adjustment image by the image reading unit 290. The print position control unit 153 controls the position of the image formed on the paper based on the image position detected by the image position detection unit 154.

[0022] Figure 2 is a diagram of the configuration of the image forming apparatus 100. The image forming apparatus 100 has an operation panel 180 on the top of the housing 201. Inside the housing 201 are the controller board 110, storage 115, paper feed unit 140, and printer engine 150 shown in Figure 1. The printer engine 150 contains the various mechanisms that make up the engine unit and an engine control unit that controls the processing performed by each mechanism. The various mechanisms that make up the engine unit include an optical processing mechanism for electrostatic latent image formation, visualization of the electrostatic latent image, and transfer of the visualized image to the paper P, and a fixing processing mechanism for fixing the toner image transferred to the paper P.

[0023] The image forming unit 152 of the printer engine 150 corresponds to an optical processing mechanism and includes a Y station 220, an M station 221, a C station 222, a K station 223, an intermediate transfer belt 252, and a secondary transfer outer roller 251. The Y station 220, M station 221, C station 222, and K station 223 have the same configuration, differing only in the color of the image they form. The Y station 220 forms a yellow image. The M station 221 forms a magenta image. The C station 222 forms a cyan image. The K station 223 forms a black image. Here, the configuration of the Y station 220 will be described, and the configurations of the M station 221, C station 222, and K station 223 will be omitted.

[0024] The Y-station 220 comprises a photosensitive drum 205, a charger 211, an exposure unit 207, and a developer unit 212. The photosensitive drum 205 is a drum-shaped photoreceptor having a photosensitive layer on its surface. The charger 211 uniformly charges the surface of the photosensitive drum 205, which rotates around the drum axis. The exposure unit 207 scans the surface of the charged photosensitive drum 205 with a laser beam modulated according to the image data.

[0025] The exposure unit 207 includes a laser driver that controls the emission of light from a semiconductor laser (not shown) according to image data acquired from the CPU 114, a rotating polyhedron mirror 208, and a reflective mirror 209. The laser light emitted from the semiconductor laser is deflected in the main scanning direction by the rotating polyhedron mirror 208 and guided to the surface of the photosensitive drum 205 by the reflective mirror 209. When the surface of the photosensitive drum 205 is exposed, an electrostatic latent image is formed.

[0026] The developer unit 212 uses toner to reveal the electrostatic latent image, forming a toner image on the surface of the photosensitive drum 205. A yellow toner image is formed on the photosensitive drum 205 of station Y 220. A magenta toner image is formed on the photosensitive drum 205 of station M 221. A cyan toner image is formed on the photosensitive drum 205 of station C 222. A black toner image is formed on the photosensitive drum 205 of station K 223.

[0027] The intermediate transfer belt 252 is mounted on rollers such as the secondary transfer inner roller 240 and rotates clockwise in the figure. The toner images of each color formed on each photosensitive drum 205 are transferred to the rotating intermediate transfer belt 252 so as to be superimposed on them. The transfer of the toner image from the photosensitive drum 205 to the intermediate transfer belt 252 is performed by applying a bias voltage to the intermediate transfer belt 252 that has characteristics opposite to those of the toner image. As a result, the intermediate transfer belt 252 carries the full-color toner image. As the intermediate transfer belt 252 rotates, it transports the carried toner image to the secondary transfer section, which consists of the secondary transfer inner roller 240 and the secondary transfer outer roller 251.

[0028] The paper feeding unit 140 corresponds to the paper feeding mechanism for the paper P and includes a storage compartment 210 for storing the paper P, a transport path, transport rollers, etc. The paper feeding unit 140 transports the paper P one sheet at a time from the storage compartment 210 to the secondary transfer unit. The secondary transfer unit uses the secondary transfer inner roller 240 and the secondary transfer outer roller 251 to grip and transport the intermediate transfer belt 252 and the paper P. At this time, a bias voltage with the opposite polarity to the toner image is applied to the secondary transfer outer roller 251, so that the toner image is transferred from the intermediate transfer belt 252 to the paper P.

[0029] The paper P onto which the toner image has been transferred is transported to the fixing unit 260, which is a fixing mechanism. The fixing unit 260 includes a fixing roller 261 having a heat source inside, a pressure roller 262 that is biased toward the fixing roller 261, and a circuit board 300 that controls the fixing process by the fixing unit 260. The fixing unit 260 fixes the toner image to the paper P by gripping and transporting the paper P with the toner image transferred between the fixing roller 261 and the pressure roller 262. At this time, the fixing roller 261 heats and melts the toner image and pressurizes the paper P between itself and the pressure roller 262.

[0030] As a result, the image is printed on the paper P. In the case of double-sided printing, the paper P with the image printed on the first side is transported again to the secondary transfer section via the inversion path 270. By being transported to the secondary transfer section via the inversion path 270, the image formation surface of the paper P is inverted. The paper P with the inverted image formation surface is then used by the secondary transfer section and the fixing section 260 to print the image on a second side that is different from the first side.

[0031] The paper P on which the image is printed passes through the image reading unit 290, which is located downstream of the fixing unit 260 in the paper transport direction, and is discharged from the image forming apparatus 100. The image reading unit 290 is used to read the adjustment image when the image formed on the paper P is an adjustment image for image forming conditions.

[0032] (Circuit board) To perform the image forming process described above, the image forming apparatus 100 is equipped with numerous actuators, such as motors and sensors. The actuators are connected to circuit boards on which control electrical components are mounted. Each electrical component mounted on the circuit board is connected by printed wiring. The electrical components control the operation of the actuators. For this purpose, numerous circuit boards are provided within the image forming apparatus 100, corresponding to the actuators. The circuit boards are controlled by the CPU 114. The controller board 110 on which the CPU 114 is mounted is also an example of a circuit board.

[0033] Figure 3 is a functional block diagram of the circuit board 300 provided in the fixing unit 260. Multiple motors 309 to 311 and multiple sensors 312 to 314 within the fixing unit 260 are electrically connected to the circuit board 300. Motor 309 is a drive source for driving the fixing roller 261, which is a rotating body. Motor 310 is a drive source for biasing the pressure roller 262 toward the fixing roller 261. Motor 311 is a drive source for driving the roller, which is a rotating body that transports the paper P after the fixing process to the next stage. Sensor 312 detects the paper P that has been transported to the fixing unit 260. Sensor 313 detects the temperature of the fixing roller 261. Sensor 314 detects the paper P after the fixing process.

[0034] The circuit board 300 implements various functions through multiple electrical components. In the example shown in Figure 3, the circuit board 300 includes an AC / DC converter 302 and a DC / DC converter 303 used to generate a desired voltage from the commercial power supply 301. Furthermore, the circuit board 300 includes a CPU 304, an ASIC (Application Specific Integrated Circuit) 305, and motor drivers 306-308 used to control the actuators. Multiple integrated circuits (ICs) and peripheral electrical components corresponding to each IC are mounted on the circuit board 300.

[0035] The AC / DC converter 302 generates a power supply voltage (DC) with a predetermined voltage value from the power (AC) supplied from the commercial power supply 301. The DC / DC converter 303 generates a power supply voltage with a different voltage value from the power supply voltage supplied from the AC / DC converter 302. The power supply voltage generated by the DC / DC converter 303 is supplied to the CPU 304 and ASIC 305, etc. The CPU 304 and ASIC 305 operate using the power supply voltage supplied from the DC / DC converter 303. The power supply voltage output from the AC / DC converter 302 is also supplied to circuits and motors 309-310 that operate at different voltage values ​​than the CPU 304 and ASIC 305.

[0036] The CPU 304 is connected to the motor drivers 306-308 and the sensors 312-314 via the ASIC 305. The CPU 304 acquires the detection results from the sensors 312-314 and detects the state of the fixing unit 260 based on these results. The CPU 304 controls the driving of the motors 309-311 by controlling the motor drivers 306-308 via the ASIC 305 according to the detected state of the fixing unit 260.

[0037] The circuit board 300 controls the operation of the fixing unit 260 because it is located on the fixing unit 260, but other circuit boards located within the image forming apparatus 100 similarly control the operation of their corresponding components. Each circuit board within the image forming apparatus 100 is communicated to the controller board 110. Communication is possible between the circuit boards via the controller board 110. Each circuit board appropriately controls the components within the image forming apparatus 100 while sharing information about the detection results of each sensor and the control status of the motors with each other.

[0038] Numerous electrical components are mounted on the circuit board 300 shown in Figure 3. However, there is a possibility that some of these electrical components may become difficult to procure. As a way to deal with situations where electrical components become difficult to procure, a common method is to pre-investigate electrical components that are identical or similar in shape and specifications to each component as possible substitutes. If a problem occurs in procuring components, the manufacturing of the circuit board can continue by procuring these substitute components and mounting them on the circuit board.

[0039] However, certain ICs, such as the DC-DC converter IC 303 and the motor driver IC 306 (or 307, 308), may require specific peripheral components for their use. Furthermore, the number, arrangement, or electrical specifications of the ICs may differ, and there may be no readily available substitute ICs. In such cases, to address the difficulty in procuring each IC, one solution is to add separate electrical components to the circuit board that have the same function as the electrical component components consisting of each IC and its peripheral components, but with different components, thereby exclusively mounting the electrical component components. This method allows for the continued manufacture of the circuit board, as the ICs are mounted according to the availability of the components.

[0040] The circuit board 300 of this embodiment has a configuration that can cope with situations where components are difficult to procure, and can reduce the area required for mounting electrical components. A specific circuit diagram and the wiring (conductor pattern) of the circuit board will be described below.

[0041] (DC converter) Figure 4 is a circuit diagram of the DC-DC converter 303. The DC-DC converter 303 exclusively comprises a first electrical component 3031 including IC 10 and a second electrical component 3032 including IC 20, which is a replaceable part of IC 10. The DC-DC converter 303 has an input section 3033 to which a predetermined power supply voltage is supplied from the AC-DC converter 302. The DC-DC converter 303 converts the supplied power supply voltage by either the first electrical component 3031 or the second electrical component 3032 into a power supply voltage with a DC voltage value different from the DC voltage value of the supplied power supply voltage. In this case, the DC-DC converter 303 converts a 12[V] power supply voltage to a 3.3[V] power supply voltage and outputs it.

[0042] In Figure 4, an input voltage VDD_IN of 12[V] is supplied from the AC / DC converter 302. When the first electrical component 3031, which includes IC10, is installed, the input voltage VDD_IN is input to terminal VIN, pin 2 of IC10. When the second electrical component 3032, which includes IC20, is installed, the input voltage VDD_IN is input to terminal VIN, pin 3 of IC20. Both the first electrical component 3031 and the second electrical component 3032 can convert the input voltage VDD_IN to the output voltage VDD_OUT and output it. The function of converting the input voltage VDD_IN to the output voltage VDD_OUT and outputting it is a function common to both IC10 and IC20.

[0043] The output enable signal is input to terminal CE of IC10 or terminal EN of IC20. The output enable signal is transmitted, for example, from the CPU 114 of the controller board 110. The output timing of the output voltage VDD_OUT of IC10 and IC20 is controlled by the output enable signal. IC10 outputs the output voltage VDD_OUT from terminal SW of terminal 3. IC20 outputs the output voltage VDD_OUT from terminal SW of terminal 2. Both IC10 and IC20 have the function of controlling the output of the output voltage VDD_OUT using the output enable signal. In addition, IC10 is supplied with the input voltage VDD_IN to terminal CE of IC10 so that it can output the output voltage VDD_OUT even if the CPU 114 does not input the output enable signal when the input voltage VDD_IN is input. Similarly, IC20 is supplied with the input voltage VDD_IN to terminal EN of IC20 so that it can output the output voltage VDD_OUT even if the CPU 114 does not input the output enable signal when the input voltage VDD_IN is input. The circuit board 300 is equipped with a resistor R1 and a capacitor C1 as electrical components used in common by IC10 and IC20 to adjust the time it takes for the output voltage VDD_OUT to transition to a state where it can be output.

[0044] IC20 outputs an output status signal from terminal 4, PG. The output status signal function is unique to IC20, and IC10 does not have a similar function. The output status signal indicates whether IC20 is outputting the output voltage VDD_OUT correctly. IC20 outputs an output status signal indicating that it is operating correctly when the output voltage VDD_OUT output from terminal 2, SW, is within the target voltage range, and outputs an output status signal indicating that it is not operating correctly when it is outside the target voltage range. For example, IC20 outputs an output status signal of 2.0[V] when operating correctly, and an output status signal of 0.8[V] when not operating correctly.

[0045] (Specific peripheral components) The first electrical component 3031 consists of IC10 and specific peripheral components necessary for the normal operation of IC10. The second electrical component 3032 consists of IC20 and specific peripheral components necessary for the normal operation of IC20.

[0046] The first electrical component 3031 includes capacitors C11, C12, C13, C14, C15, C16, and resistor R10 as peripheral components for IC10. The second electrical component 3032 includes capacitors C21, C22, C23, C24, C25, and C26 as peripheral components for IC20. Capacitors C11-C13 of the first electrical component 3031 and capacitors C21-C23 of the second electrical component 3032 have the same function of removing noise from the input voltage VDD_IN. However, capacitors C11-C13 and capacitors C21-C23 have different capacitances in order to maintain the operating performance of IC10 and IC20.

[0047] The first electrical component 3031 and the second electrical component 3032 are mounted exclusively on the circuit board 300. However, the circuit board 300 may be configured so that IC10 and IC20 are mounted exclusively on it. For example, the peripheral components of IC10 and IC20 may be pre-mounted, and IC10 and IC20 may be mounted exclusively on the circuit board 300 depending on the availability of electrical components. Alternatively, the first electrical component 3031 may consist of IC10 and its peripheral components as a single package, and the second electrical component 3032 may consist of IC20 and its peripheral components as a single package. In this case, the first electrical component 3031 and the second electrical component 3032 are mounted exclusively on the circuit board 300 as a package.

[0048] (Common peripheral parts) The DC-DC converter 303 is composed of electrical components that are used in common by IC10 and IC20. These commonly used electrical components include peripheral components such as capacitors C1, C2, C3, C4, C5, C6, resistors R1, R2, R3, and inductor L1.

[0049] Inductor L1 and capacitors C2-C5 are connected to the output line of the output voltage VDD_OUT and have the function of smoothing the output voltage VDD_OUT. Inductor L1 and capacitors C2-C5 are among the larger electrical components used in the DC-DC converter 303. In the circuit board 300, which exclusively mounts the first electrical component 3031 and the second electrical component 3032, treating large components as common electrical components as much as possible is effective in reducing wasted mounting area.

[0050] Resistors R2 and R3 are voltage divider resistors that divide the output voltage VDD_OUT. The voltage division result (divided voltage) of the output voltage VDD_OUT by resistors R2 and R3 is input to the respective feedback terminals of IC10 and IC20. The feedback terminal of IC10 is terminal 5 FB. The feedback terminal of IC20 is terminal 6 VFB. The feedback terminals monitor whether the output voltage VDD_OUT has reached the target voltage based on the divided voltage. Capacitor C6 removes the AC component from the output voltage VDD_OUT.

[0051] IC10 and IC20 determine whether the output voltage VDD_OUT is output at a normal voltage value by using the divided voltage. If the output voltage VDD_OUT is lower than the target voltage, IC10 and IC20 internally short-circuit terminal SW and terminal VIN, and if it is higher than the target voltage, they internally short-circuit terminal SW and terminal GND (ground). For this reason, the divided voltage input to the feedback terminal becomes a reference signal for controlling the output voltage VDD_OUT. The feedback terminal, like terminal SW, is a terminal required for both IC10 and IC20. For this reason, the resistors R2 and R3 and capacitor C6 that generate the divided voltage input to the feedback terminal are electrical components used in common by IC10 and IC20.

[0052] (Circuit board mounting area) Figure 5 is an explanatory diagram of the DC-DC converter 303 on the circuit board 300. The circuit board 300 has a four-layer structure. Figure 5 illustrates the first, third, and fourth layers. The second layer is not shown because it is entirely grounded. The first layer is the component side (first surface), and mainly common peripheral components and the first electrical component 3031 are mounted on it. The third layer has the wiring (conductor pattern) for the terminal SW that outputs the output voltage VDD_OUT of IC10, and a grounding conductor pattern. The fourth layer is the solder side (second surface), and mainly the second electrical component 3032 is mounted on it. In other words, IC10 can be mounted on one side (first surface) of the circuit board 300, and IC20 can be mounted on the other side (second surface) of the circuit board 300. The mounting areas for IC10 and IC20 are located opposite each other across the circuit board 300.

[0053] When the first mounting area Z1 on which IC10 is mounted and the second mounting area Z2 on which IC20 is mounted are projected onto a virtual plane parallel to the circuit board 300, the first mounting area Z1 encompasses the second mounting area Z2. Furthermore, when the first mounting area Z1 and the second mounting area Z2 are projected onto a virtual plane parallel to the circuit board 300, a portion of the first mounting area Z1 projected onto the virtual plane may overlap with the second mounting area Z2 projected onto the virtual plane. In other words, the first mounting area Z1 has an overlapping area on the virtual plane when the first mounting area Z1 and the second mounting area Z2 are projected onto a virtual plane parallel to the circuit board 300. This reduces the mounting area compared to a configuration where IC10 and IC20 are exclusively mounted on the same surface, thus suppressing the expansion of the circuit board 300's area.

[0054] Common peripheral components such as inductor L1, capacitors C1-C6, and resistors R1-R3 are mounted on the first layer, which is the component side. Therefore, IC10 of the first electrical component 3031 is electrically connected to inductor L1, capacitors C1-C6, and resistors R1-R3 by the wiring (conductor pattern) of the first layer. For example, the component side of the circuit board 300 has nine pads as mounting areas for attaching the terminals of IC10, and a conductor pattern formed to electrically connect the pads to inductor L1. On the other hand, IC20 of the second electrical component 3032 is mounted on the fourth layer, which is the solder side, and is electrically connected to inductor L1 via four vias. For example, the solder side of the circuit board 300 has eight pads as mounting areas for attaching the terminals of IC20, and a conductor pattern formed to electrically connect the pads to inductor L1 on the mounting side via four vias. Furthermore, these four vias are part of the wiring that connects IC10 to capacitor C14 included in the first electrical component 3031. IC10 and capacitor C14 are connected via the third layer. In other words, capacitor C14 of the first electrical component 3031 is mounted on the fourth layer. In this embodiment, the board area is reduced by including vias.

[0055] The second layer is fully grounded, but the third layer also has a large grounded area. The second layer provides grounding for IC10 on the first layer, and the third layer provides grounding for IC20 on the fourth layer. Large grounding areas are formed on the second and third layers to suppress noise generated by IC10 and IC20, which are ICs of the DC-DC converter 303, and to improve heat dissipation characteristics. When the layers from the first to the fourth layer are aligned in a straight line, vias for connecting to ground are used in common for IC10 and IC20. For this reason, the grounding of the second layer and the grounding of the third layer are connected via vias.

[0056] By using common peripheral components, the board area occupied by the second electrical component 3032 is only about 30-40% of the fourth layer, which is the solder side. If the first electrical component 3031 and the second electrical component 3032 could be mounted without using common peripheral components, additional peripheral electrical components that could be used in common for the second electrical component 3032 would be required, increasing the board area. In particular, when mounting large components such as inductors L1 on both sides of the circuit board 300 using reflow soldering, the possibility of dropping or colliding increases, potentially reducing the mounting yield. Therefore, large components such as inductors should be placed on one side of the circuit board 300. If the inductors of each unit were to be placed on the component side, taking into account the mounting yield of the circuit board 300, it is estimated that an area 1.5 to 2 times larger than the wiring (conductor pattern) area in Figure 5 would be required.

[0057] In this embodiment, the inductor L1, capacitors C1 to C6, resistors R1 to R3, and various vias are treated as common peripheral components for IC10 and IC20. This allows the two units (first electrical component 3031 and second electrical component 3032) to be placed on both sides of the circuit board 300, while significantly reducing wasted unused space on the circuit board 300 due to mutual exclusion mounting.

[0058] Furthermore, the above description mentions the case where the first mounting area Z1 of IC10 is larger than the second mounting area Z2 of IC20, but the circuit board 300 is not limited to the above configuration. For example, if the second mounting area Z2 of IC20 is larger than the first mounting area Z1 of IC10, the second mounting area Z2 may be configured to encompass the first mounting area Z1 when the first mounting area Z1 and the second mounting area Z2 are projected onto a virtual plane parallel to the circuit board 300. Alternatively, when the first mounting area Z1 and the second mounting area Z2 are projected onto a virtual plane parallel to the circuit board 300, a portion of the first mounting area Z1 projected onto the virtual plane may overlap with the second mounting area Z2 projected onto the virtual plane. This reduces the mounting area compared to a configuration where IC10 and IC20 are exclusively mounted on the same surface, thus suppressing the expansion of the area of ​​the circuit board 300.

[0059] In the above explanation, the DC-DC converter 303 was used as an example for IC10 and IC20, but even if it is a motor driver IC that controls the drive of a motor, it can be configured in a way that allows the IC to be mounted on both the component side and the solder side of the circuit board 300. For example, IC10 and IC20 are motor driver ICs included in motor drivers 306, 307, and 308 that drive and control motors 309, 310, and 311. With such a configuration, it is possible to significantly reduce the area of ​​wiring (conductor patterns) on the circuit board 300.

Claims

1. A circuit board for an image forming apparatus, wherein either a first integrated circuit or a second integrated circuit different from the first integrated circuit is exclusively provided, Electrical components provided on the first surface of the circuit board, A first mounting portion is provided on the first surface of the circuit board and is configured to allow the attachment of terminals of the first integrated circuit, A first conductor pattern formed on the first surface and constituting at least a part of the first wiring that connects the first mounting portion and the electrical component, A second mounting portion is provided on the second surface of the circuit board opposite to the first surface, and is configured to allow the attachment of terminals of the second integrated circuit, A second conductor pattern formed on the second surface and constituting a part of the second wiring that connects the second mounting portion and the electrical component, A circuit board characterized by having vias that penetrate the circuit board and constitute another part of the second wiring.

2. The circuit board according to claim 1, characterized in that the via is electrically connected to the first conductor pattern.

3. The circuit board further includes an input section into which a voltage is input, The circuit board according to claim 1, characterized in that it converts the voltage value input from the input unit.

4. The circuit board according to claim 1, characterized in that it controls a drive source electrically connected to the circuit board.

5. The circuit board according to claim 1, characterized in that the arrangement of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the arrangement of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

6. The circuit board according to claim 1, characterized in that the number of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the number of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

7. A first region on the first surface where the first integrated circuit is arranged, The second surface has a second region in which the second integrated circuit is arranged, The circuit board according to claim 1, characterized in that when the first region is projected onto the second region in a direction perpendicular to the first region, the projection of the first region at least partially overlaps with the second region.

8. An image forming apparatus for forming an image on paper, A circuit board is provided exclusively with either a first integrated circuit or a second integrated circuit different from the first integrated circuit, and the circuit board has conversion means for converting the value of a voltage input to the circuit board. The aforementioned circuit board is Electrical components provided on the first surface of the circuit board, A first mounting portion is provided on the first surface of the circuit board and is configured to allow the attachment of terminals of the first integrated circuit, A first conductor pattern formed on the first surface and constituting at least a part of the first wiring that connects the first mounting portion and the electrical component, A second mounting portion is provided on the second surface of the circuit board opposite to the first surface, and is configured to allow the attachment of terminals of the second integrated circuit, A second conductor pattern formed on the second surface and constituting a part of the second wiring that connects the second mounting portion and the electrical component, An image forming apparatus characterized by having a via that penetrates the circuit board and constitutes another part of the second wiring.

9. The image forming apparatus according to claim 8, characterized in that the via is electrically connected to the first conductor pattern.

10. The image forming apparatus according to claim 8, characterized in that the arrangement of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the arrangement of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

11. The image forming apparatus according to claim 8, characterized in that the number of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the number of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

12. A first region on the first surface where the first integrated circuit is arranged, The second surface has a second region in which the second integrated circuit is arranged, The image forming apparatus according to claim 8, characterized in that when the first region is projected onto the second region in a direction perpendicular to the first region, the projection of the first region at least partially overlaps with the second region.

13. An image forming apparatus comprising: a rotating body that rotates to form an image on paper; a drive source; and a circuit board on which either a first integrated circuit or a second integrated circuit different from the first integrated circuit is exclusively provided, and which controls the drive source to rotate the rotating body, wherein the image forming apparatus comprises: The aforementioned circuit board is Electrical components provided on the first surface of the circuit board, A first mounting portion is provided on the first surface of the circuit board and is configured to allow the attachment of terminals of the first integrated circuit, A first conductor pattern formed on the first surface and constituting at least a part of the first wiring that connects the first mounting portion and the electrical component, A second mounting portion is provided on the second surface of the circuit board opposite to the first surface, and is configured to allow the attachment of terminals of the second integrated circuit, A second conductor pattern formed on the second surface and constituting a part of the second wiring that connects the second mounting portion and the electrical component, An image forming apparatus characterized by having a via that penetrates the circuit board and constitutes another part of the second wiring.

14. The image forming apparatus according to claim 13, characterized in that the via is electrically connected to the first conductor pattern.

15. The image forming apparatus according to claim 13, characterized in that the arrangement of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the arrangement of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

16. The image forming apparatus according to claim 13, characterized in that the number of terminals of the first mounting portion corresponding to the terminals of the first integrated circuit is different from the number of terminals of the second mounting portion corresponding to the terminals of the second integrated circuit.

17. A first region on the first surface where the first integrated circuit is arranged, The second surface has a second region in which the second integrated circuit is arranged, The image forming apparatus according to claim 13, characterized in that when the first region is projected onto the second region in a direction perpendicular to the first region, the projection of the first region at least partially overlaps with the second region.

Images