Blank circuit boards, circuit boards, and display devices

Abstract

To provide a circuit board with reduced radiated noise. [Solution] A blank substrate used as a boost circuit board and a buck-boost circuit board depending on the components to be mounted, comprising a substrate and wiring HI, HM, Hm, HO formed on the substrate, wherein the wiring HI, HM, Hm, HO forms a first mounting land for mounting boost circuit elements, a second mounting land for mounting buck-boost circuit elements, and a shared mounting land used in both the boost circuit and the buck-boost circuit, and the shared mounting land has a single diode mounting land.

Description

Technical Field

[0001] The present invention relates to a circuit board.

Background Art

[0002] As a conventional circuit board, for example, a circuit board included in an in-vehicle control device disclosed in Patent Document 1 is known. In Patent Document 1, the circuit board has a power supply (5) connected to an in-vehicle battery and a microcomputer (1), and the power supply (5) is a DC-DC converter that converts (steps down) the battery voltage of 12.5V of the in-vehicle battery to 5V.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In many cases, either a DC-DC converter that supports either step-down or step-up or a SEPIC that supports both step-up and step-down conversion is mounted on the circuit board according to the specifications of the mounted device. Here, when making the blank boards common to each specification, the easiest commonization measure is to form dedicated mounting areas (wiring areas) in different areas within the blank board. However, in this case, the unused mounting areas become extensive unmounted areas, that is, the mounting areas are wasted, leading to a decrease in the freedom of artwork and an increase in cost.

[0005] Therefore, as another commonization measure, a commonization circuit that can realize a desired circuit by switching the mounted components according to both specifications may be used. However, in the conventional commonization circuit, unnecessary wiring length occurs, and this wiring impedance may not be preferable in terms of radiated noise.

[0006] Therefore, the objective of the present invention is to address the above-mentioned problems and provide a blank substrate, a circuit board, and a display device that can reduce radiated noise by minimizing unnecessary wiring while achieving circuit commonality. [Means for solving the problem]

[0007] To achieve the above objective, the blank substrate according to the present invention is A blank circuit board used as a boost circuit board or a buck-boost circuit board, depending on the components to be mounted, circuit board and Wiring formed on the aforementioned substrate, Equipped with, The aforementioned wiring is The first mounting pad for mounting components for the boost circuit, A second mounting pad for mounting components for a step-up / step-down circuit, A shared mounting pad used in both boost circuits and buck-boost circuits, Forming, The shared mounting land has a single diode mounting land.

[0008] To achieve the above objective, the circuit board according to the present invention is The boost circuit element mounted on the first mounting pad, A common element mounted on the aforementioned common mounting land, It is equipped with.

[0009] To achieve the above objective, the circuit board according to the present invention is The boost circuit element mounted on the second mounting pad, A common element mounted on the aforementioned common mounting land, It is equipped with.

[0010] To achieve the above objective, the display device according to the present invention is The system includes the circuit board described above. [Brief explanation of the drawing]

[0011] [Figure 1] Circuit diagram showing the electrical circuit related to the circuit board CB of the present disclosure. [Figure 2] Diagram showing the artwork of the circuit board CB. [Figure 3] Enlarged view of the main part III of the circuit board CB. [Figure 4] Circuit diagram in a conventional configuration. [Figure 5] Diagram showing the artwork of the circuit board CB1 in a conventional configuration. [Figure 6] Enlarged view of the main part VI of the circuit board CB1 in a conventional configuration.

Embodiments for Carrying out the Invention

[0012] Each embodiment will be described in the following order while referring to the accompanying drawings. In some of the figures, for the sake of clarity, reference numerals may be omitted for some parts having the same attributes that exist in plurality. [First Embodiment] 1-1. Description of the Configuration 1-2. Description of the Mounting 1-3. Description of the Behavior 1-4. Comparison with the Conventional Example [Effect Example] [Modification Example]

[0013] [First Embodiment] <1-1. Description of the Configuration> FIG. 1 is a circuit diagram showing a part of the circuit configuration of the electrical component (including the circuit board CB according to the present disclosure) mounted on the vehicle C. The vehicle C is a vehicle such as a four-wheel automobile, a motorcycle, a work vehicle, etc., but may be a moving body such as a ship or an aircraft. The vehicle C includes a battery BTT, a circuit board CB (inside the thick broken line in FIG. 1), and a load 5.

[0014] The vehicle battery BTT consists of a lead-acid battery or the like, and supplies a predetermined amount of power to electrical components with a rated power supply voltage of 12.5V. These electrical components include a load 5 connected via a circuit board CB. The battery BTT is connected to the circuit board CB by wiring such as a harness.

[0015] Load 5 can be any of the various in-vehicle electronic components, such as a display device. The display device displays various information to the occupants of vehicle C or to people outside of vehicle C. Examples of display devices include meters, center information displays, and head-up display devices. As load 5, it is particularly preferable to use the light source of a head-up display device, which requires high voltage and consumes high power because it consists of high-brightness LEDs connected in series. However, load 5 can be any other in-vehicle electronic component that consumes power.

[0016] Circuit board CB is configured as a power supply circuit board, so to speak, which converts the power supply voltage into an appropriate input voltage for load 5 using the circuit (power supply circuit) that is mounted on it. A circuit board (CB) is constructed by mounting various electrical and electronic components onto the mounting surface of a blank substrate, which consists of a substrate and wiring. The blank substrate is composed of a substrate, such as a glass epoxy substrate (FR4), and a printed wiring pattern, which is copper foil printed on the substrate. The blank board only needs to have a base material and wiring pattern that can be used to construct a circuit board. The base material can be FR-1, FR-2, FR-3, or an aluminum substrate (including an insulating layer), and the wiring pattern can be made of something other than copper foil.

[0017] <1-2. Implementation Description> Referring to Figure 1, we will now explain the circuit board CB in detail from a mounting perspective. Although Figure 1 was described as showing the circuit diagram of the circuit board CB, in reality, some of the elements shown in the diagram will not be mounted depending on the specifications.

[0018] Specifically, if the specifications of load 5 require an input voltage higher than the power supply voltage, circuit board CB will be configured as a boost circuit board. In this configuration, the boost / buck circuit elements (indicated by the dashed lines: capacitor 32, inductor 33, resistor 34) will not be implemented, and only the shared elements (indicated by the dashed lines: capacitor 1, inductor 2, switching element 3, capacitor 4, diode 21) and the boost circuit elements (indicated by the dashed line: resistor 22) will be implemented.

[0019] On the other hand, in the case where the power supply voltage can be both boosted and bucked as input voltage according to the specifications of load 5, circuit board CB is configured as a buck-boost circuit board, and therefore no boost circuit elements are mounted, while shared elements and buck-boost circuit elements are mounted.

[0020] The switching element 3, which serves as a shared element, includes a DC-DC converter (in the boost circuit) and a SEPIC (in the buck-boost circuit), but other switching elements may also be used.

[0021] Figure 2 shows a portion of the artwork on the mounting surface of the circuit board CB. Figure 3 shows a magnified view of the main part III, enclosed by the dashed line in the center of Figure 2.

[0022] Circuit board CB may implement only the power supply circuit described so far, or it may implement other circuits (including load 5) on the same board. A solid ground pattern (ground G) is formed in areas other than the high-potential wiring HI, HM, HO and the mounting lands, with a predetermined margin. Areas with hatching indicate typical wiring areas that are relatively high in potential. For ease of viewing, the wiring 3b within the switching element 3 is hatched upwards to the left, while the other wirings are hatched upwards to the right.

[0023] The switching element 3 can be configured to perform switching operations, but for example, it may consist of a switching IC 3a, wiring 3b, and a shunt resistor 3c.

[0024] As shown in the lower right of Figure 2, wiring HI is connected to the positive terminal of battery BTT via a harness or the like. Wiring HI forms the positive terminal mounting land for capacitor 1 and inductor 2. Although a detailed illustration of the mounting land is omitted, it is formed appropriately within the overlapping area between each element (or its terminal) and each wiring.

[0025] The negative side mounting land for inductor 2 is formed on wiring HM. Wiring HM further forms one of the mounting lands for switching element 3 (switching IC 3a), capacitor 32, and resistor 22.

[0026] The other side of the mounting land for capacitor 32 is formed on wiring Hm. Wiring Hm further forms the positive side mounting land for inductor 33 and resistor 34.

[0027] The negative side mounting pads for resistors 22 and 34 are both formed on the anode side wiring of diode 21. The cathode-side wiring HO of diode 21 forms the positive-side mounting pad for capacitor 4 and connector 5c.

[0028] The negative side mounting pads for capacitor 1, switching element 3, inductor 33, and capacitor 4 are formed on ground G.

[0029] Capacitors 1, 32, and 4 may be installed individually or in multiple quantities so that their capacitance is a predetermined value. Inductors 2 and 33 may be installed individually or in multiple real numbers so that their induction coefficient is a predetermined value. Resistors 22 and 34 are simply jumper resistors that conduct wires together, and therefore have an impedance of 0Ω. Connector 5c is electrically connected to the external load 5 of the circuit board CB and outputs the power supplied by the vehicle battery BTT at the transformed input voltage.

[0030] Here, the land on which the boost circuit elements are mounted is referred to as the first mounting land, the land on which the boost / buck circuit elements are mounted is referred to as the second mounting land, and the land on which the shared elements are mounted is referred to as the shared mounting land.

[0031] <1-3. Explanation of Behavior> Here, we will explain the noise emitted by the circuit board CB, divided into two cases: when the circuit board CB is configured as a boost circuit and when it is configured as a buck-boost circuit. (1-3-1. Boost Circuit) Circuit board CB emits relatively large radiated noise during voltage transformation due to the current flowing through the switching node and the wiring impedance (line length). Therefore, in this case, where the circuit configuration is relatively simple, the switching node section, including the boost circuit elements, is formed to be short. Specifically, the switching node section in this case consists of the switching element 3, wiring HM, resistor 22, diode 21, capacitor 4, ground G, and the line formed by connecting these. As shown in the figure, these switching node sections are adjacent to each other, resulting in the shortest possible line length and thus the smallest wiring impedance. Consequently, radiated noise is minimized.

[0032] (1-3-2. Step-up / Step-down Circuit) Similarly, even if the circuit board CB is a step-up / step-down circuit, radiated noise is generated from the switching node. In this case, where the circuit configuration is relatively complex, the switching node is the path R around the outer perimeter, which bypasses the resistor 22. Specifically, it is the line formed by connecting the switching element 3, wiring HM, capacitor 32, wiring Hm, resistor 34, diode 21, capacitor 4, and ground G. However, the presence or absence of resistors 22 and 34 allows for the common placement of the diode 21's mounting land, resulting in a relatively short path R. In a circuit board CB configured in this way, radiated noise can be suitably reduced, as can be seen from the perspective of comparison with the conventional example described later.

[0033] <1-4. Comparison with previous examples> Here, the configuration of a conventional circuit board will be explained using Figures 4 to 6, with the example of circuit board CB1 mounted on vehicle C1, and will be compared with the circuit board of this disclosure. Note that elements with the same reference numerals in the drawings are the same elements as those in Figures 1 to 3, and therefore detailed explanations will be omitted.

[0034] Figure 4 is a circuit diagram of a conventional example in which the boost circuit and the buck-boost circuit share a common circuit board. Similar to Figure 1, among the elements that can be mounted on circuit board CB1, common elements are enclosed by dashed lines, elements for the boost circuit are enclosed by dashed lines, and elements for the buck-boost circuit are enclosed by double-dashed lines. Compared to circuit board CB of this disclosure, circuit board CB1 does not include resistors 22 and 34. In addition, a diode 31 is provided as an element for the buck-boost circuit. The diode 31 is located between wiring Hm1 and wiring HO1. Its positive side mounting land is formed on wiring Hm1, and its negative side mounting land is formed on HO1. Wirings such as HM1, Hm1, and HO1 have different shapes compared to the wiring of circuit board CB, depending on the differences in the elements mounted.

[0035] Next, the artwork for circuit board CB1 based on this circuit diagram is shown in Figure 5. Furthermore, the main part VI in the center of Figure 5 is shown in an enlarged view in Figure 6. As explained in Figure 4, in the conventional example where resistors 22 and 34 are not included, resistors 22 and 34 are not present. Therefore, the commonization of diode mounting lands based on the presence or absence of resistors 22 and 34, which was done in the circuit board CB of this disclosure, is not achieved, resulting in unnecessary wire length.

[0036] Specifically, the switching node section in the boost circuit where diode 21 is implemented is not significantly different from that of circuit board CB, but the switching node section (path R1) in the buck-boost circuit using diode 31 is shifted to the left side of the diagram to bypass the implementation area of ​​diode 21, resulting in an increase in line length and wiring impedance.

[0037] Therefore, when comparing the conventional circuit board CB1 with the circuit board CB of this disclosure, radiated noise was reduced due to the difference in line length between path R1 and path R.

[0038] [Example of effect] The first blank circuit board is A blank circuit board used as a boost circuit board or a buck-boost circuit board, depending on the components to be mounted, circuit board and The wiring HI, HM, Hm, HO formed on the substrate, Equipped with, Wiring types HI, HM, Hm, HO are: The first mounting pad for mounting components for the boost circuit, A second mounting pad for mounting components for a step-up / step-down circuit, A shared mounting pad used in both boost circuits and buck-boost circuits, Forming, The shared mounting land has a single diode mounting land for diode 21.

[0039] The second circuit board CB is, The first blank circuit board, The boost circuit element (within the dashed line in Figure 1; resistor 22) is mounted on the first mounting pad, The shared elements (within the dashed lines in Figure 1; capacitor 1, inductor 2, switching element 3, capacitor 4) are mounted on the aforementioned shared mounting land, It is equipped with.

[0040] The third circuit board CB is, The first blank circuit board, The boost circuit components (within the dashed line in Figure 1: capacitor 32, inductor 33, resistor 34) are mounted on the second mounting pad, The shared elements (within the dashed lines in Figure 1; capacitor 1, inductor 2, switching element 3, capacitor 4) are mounted on the aforementioned shared mounting land, It is equipped with.

[0041] The fourth display device is, It comprises either a second circuit board or a third circuit board.

[0042] [Differentiation] Although the blank substrate, circuit board, and display device of the present invention have been described using the configuration of the above-described embodiment as an example, the present invention is not limited thereto, and various improvements and changes to the display are possible in other configurations without departing from the spirit of the present invention.

[0043] For example, while examples of blank substrates that can be used as both boost and buck-boost circuits have been shown, the blank substrate may be configured to share not only a substrate for boost circuits and a substrate for buck-boost circuits, but also a substrate for buck circuits. [Explanation of Symbols]

[0044] 1,4,32 Capacitors 2.33 Inductors 22,34 resistors 3 Switching elements 5c connector 5 load 21,31 diodes BTT Battery CB circuit board G Ground HI,HM,Hm,HO wiring Route R,R1

Claims

1. A blank circuit board used as a boost circuit board or a buck-boost circuit board, depending on the components to be mounted, circuit board and Wiring formed on the aforementioned substrate, Equipped with, The aforementioned wiring is The first mounting pad for mounting components for the boost circuit, A second mounting pad for mounting components for a step-up / step-down circuit, A shared mounting pad used in both boost circuits and buck-boost circuits, Forming, The shared mounting land has a single diode mounting land. A blank substrate characterized by the following features.

2. A blank substrate according to claim 1, The boost circuit element mounted on the first mounting pad, A common element mounted on the aforementioned common mounting land, Equipped with A circuit board that is a voltage boosting circuit board characterized by the above.

3. A blank substrate according to claim 1, The boost circuit element mounted on the second mounting pad, A common element mounted on the aforementioned common mounting land, Equipped with A circuit board that is a step-up / step-down circuit board characterized by the above.

4. The circuit board comprises the circuit board described in either claim 2 or 3. Vehicle display device.

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