Circuit board

Abstract

To provide a circuit board that can further reduce noise.SOLUTION: On a circuit board 10, a power connector 20 to which power from a power source is input, a control part 40 that controls the display of a display part using the power input from the power connector 20 as operation power, and a noise filter element 33 that is electrically connected to the power connector 20 and the control part 40 and eliminates noise are mounted. The circuit board 10 includes a plurality of conductor layers L1 to L4 arranged in a Z direction. The plurality of conductor layers L1 to L4 each have a ground pattern. The ground pattern is formed in a range that includes a part of the noise filter element 33 when viewed from the Z direction of the circuit board 10, and in an area except for a ground extraction area 43 set in a corner of the circuit board 10.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses that a connector and a drive driver are mounted on a circuit board, and the power input to the connector is supplied to the drive driver via a printed wiring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of the above Patent Document 1, reduction of noise generated by the circuit board has been demanded.

[0005] The present disclosure has been made in view of the above situation, and an object thereof is to provide a circuit board capable of reducing more noise.

Means for Solving the Problems

[0006] To achieve the above object, a circuit board according to the present disclosure is a circuit board including a connector to which power from a battery mounted on a vehicle is input, a control unit that controls the display of a display device using the power input from the connector as an operating power source, and a noise filter element that is electrically connected between the connector and the control unit and reduces noise, including a plurality of conductor layers arranged in the thickness direction of the circuit board, wherein one or more of the plurality of conductor layers include a ground pattern, The ground pattern is formed in a range including at least a part of the noise filter element as viewed from the thickness direction of the circuit board, and outside the ground cutout region set at the corner of the circuit board.

Advantages of the Invention

[0007] According to the present disclosure, noise can be further reduced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] An in-vehicle display device having a circuit board according to an embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the in-vehicle display device 1 includes a display unit 3 and a control board unit 4. The display unit 3 displays vehicle information under the control of the control board unit 4. The display unit 3 For example, it is a liquid crystal display panel, an organic EL (Electro-Luminescence) display, or a pointer-type instrument. Note that the in-vehicle display device 1 may be a head-up display device, and the display unit 3 may emit the display light of the head-up display device.

[0010] The control board unit 4 controls the display unit 3 by receiving power from the power source 5 which is an in-vehicle battery. The control board unit 4 includes a circuit board 10, a power connector 20, a signal connector 25, a noise filter element 33, and a control unit 40. The connectors 20, 25, the noise filter element 33, and the control unit 40 are mounted on the circuit board 10. The power connector 20, the noise filters 31, 32, and the control unit 40 are electrically connected by wiring A1, A2 formed by the wiring patterns of the circuit board 10 to form a circuit.

[0011] The power connector 20 includes a power terminal portion 20i for inputting power from the power source 5 and a ground terminal portion 20o connected to the ground GND.

[0012] The noise filter 31 is provided on the wiring A1 between the power terminal portion 20i and the control unit 40. The noise filter 32 is provided on the wiring A2 between the ground terminal portion 20o and the control unit 40. The noise filters 31, 32 are common mode filters or inductors. The noise filters 31, 32 reduce the noise generated in the wirings A1, A2. Specifically, the noise filters 31, 32 have the function of making it difficult for the noise generated in the control unit 40 to pass to the power source 5 side. The noise emitted from the circuit board 10 is reduced by the noise filters 31, 32. The noise filters 31, 32 may be known noise reduction means other than common mode filters or inductors.

[0013] The signal connector 25 inputs the information signal If from the vehicle ECU (Electronic Control Unit) and outputs the input information signal If to the control unit 40.

[0014] The control unit 40 is a microcontroller that operates by receiving power from the power supply 5 and performs control to display the information based on the input information signal If on the display unit 3. The control unit 40 includes a power supply terminal 40i and a ground terminal 40o. The power supply terminal 40i is electrically connected to the power supply terminal portion 20i of the power connector 20 through the wiring A1, and inputs the current that has passed through the noise filter 31 from the power supply terminal portion 20i. The ground terminal 40o is electrically connected to the ground terminal portion 20o of the power connector 20 through the wiring A2, and outputs the current that has passed through the noise filter 31 to the ground terminal portion 20o.

[0015] The current from the power supply 5 flows in the order of power supply terminal portion 20i → noise filter 31 → control unit 40 → noise filter 32 → ground terminal portion 20o → the ground GND outside the circuit board 10.

[0016] The circuit board 10 is a printed circuit board and is formed in a rectangular plate shape, more precisely, in a rectangular plate shape with rounded corners. In the following description, the longitudinal direction of the circuit board 10 is defined as the X direction, the short-side direction of the circuit board 10 is defined as the Y direction, and the thickness direction of the circuit board 10 is defined as the Z direction.

[0017] As shown in FIG. 2, the circuit board 10 has mounting surfaces 10a and 10b formed on both sides in the Z direction. The control unit 40 and the noise filter element 33 are mounted on the mounting surface 10a. The connectors 20 and 25 are mounted on the mounting surface 10b. As shown in FIG. 3, the circuit board 10 includes four sides S1 to S4 when viewed from the Z direction. The sides S1 and S4 each extend in the Y direction and are parallel to each other. The sides S2 and S3 each extend in the X direction and are parallel to each other.

[0018] When viewed from the Z direction, the power connector 20 is located on or near side S1, closer to side S2, that is, closer to the corner formed by sides S1 and S2. "Closer to side S2" means a position closer to side S2 than the central position of side S1 in the Y direction. As shown in FIG. 7, the signal connector 25 is adjacent to the power connector 20 in the Y direction and is located farther from side S2 than the power connector 20.

[0019] As shown in FIG. 4, the noise filter element 33 is provided at a position around the corner formed by sides S1 and S2 (a position straddling the outer contour line of the ground cutout region 43 described later), and the control unit 40 is provided closer to the center position of the circuit board 10 than the noise filter element 33. The position of the noise filter element 33 will be described in detail later.

[0020] Next, the layer structure of the circuit board 10 will be described. As shown in FIG. 2, the circuit board 10 includes a plurality of conductor layers L1 to L4 stacked in the Z direction. The plurality of conductor layers L1 to L4 are stacked in the order of conductor layer L1 → L2 → L3 → L4 in the Z direction. An insulating layer is formed between each of the conductor layers L1 to L4, and the wiring patterns between each of the conductor layers L1 to L4 are electrically connected by vias and through holes. As shown in FIG. 4, the control unit 40 and the noise filter element 33 are mounted on the mounting surface 10a of the conductor layer L4 (the surface of the conductor layer L4 opposite to the conductor layer L3). As shown in FIG. 7, the connectors 20 and 25 are mounted on the mounting surface 10b of the conductor layer L1 (the surface of the conductor layer L1 opposite to the conductor layer L2). Note that the connectors 20 and 25 may be mounted on the same surface as the noise filter element 33.

[0021] As shown in FIGS. 4 to 7, each of the conductor layers L1 to L4 has a ground pattern 45. The ground pattern 45 is for electrical grounding and is formed to constitute a current return path (for example, wiring A2) of the electrical circuit formed by the circuit board 10. The ground pattern 45 is also called a solid ground and is continuously formed in a range excluding signal wirings, solder joints, and through holes. In each of the conductor layers L1 to L4, a ground pattern 45 is formed in a region other than the ground cutout region 43, and no ground pattern 45 is formed within the ground cutout region 43. In other words, in each of the conductor layers L1 to L4, the ground pattern 45 is formed with a cutout in the ground cutout region 43.

[0022] The ground cutout regions 43 are formed in regions that overlap each other in the Z direction. The ground cutout regions 43 are set in a range including a part of the noise filter 31 in the Z direction. The ground cutout regions 43 are formed in a rectangular shape, precisely a rectangular shape that is long in the Y direction, at the corner formed by sides S1 and S2.

[0023] On the circuit board 10, a non-mounting range 44 where no element 38 is mounted is formed. The non-mounting range 44 is set at the corner formed by sides S1 and S2. The non-mounting range 44 is located within the ground cutout region 43 and is formed in a rectangular shape, precisely a rectangular shape that is long in the Y direction.

[0024] As shown in FIG. 3, a plurality of elements 38 other than the noise filter element 33 are mounted in a region of the circuit board 10 other than the non-mounting range 44. The elements 38 are diodes, capacitors, resistors, transistors, integrated circuits, etc. A wiring pattern (not shown) is formed at the position on the circuit board 10 where the element 38 is mounted. Therefore, no wiring pattern is formed in the non-mounting range 44. Note that the wiring pattern not formed in the non-mounting range 44 is a wiring pattern directly connected to the element 38, and a conductive pattern (described later) that connects the noise filter element 33 and the connector 20 may be formed in the non-mounting range 44. Also, this conductive pattern is a so-called power line and includes wirings (branching wirings, checklands, vias) at the same potential. Also, in addition to the noise filter element 33, other noise filter elements that reduce the noise of the conductive pattern may be mounted in the non-mounting range 44. As other noise filter elements, known noise reduction means such as a common mode filter or an inductor, a ceramic capacitor, etc. can be applied.

[0025] As shown in FIG. 4, the conductor layer L4 includes, as a conductive pattern, a ground pattern 45 including a low potential pattern 42g, high potential patterns 41h and 42h, a low potential pattern 41g, and a control signal pattern 46. The control signal pattern 46 is formed so as to conduct between the signal connector 25 and the control unit 40. The control signal pattern 46 is surrounded by the ground pattern 45 with a gap.

[0026] The high potential pattern 41h and the low potential pattern 41g are formed in the groundless region 43 of the conductor layer L4 and are parts that conduct with the power connector 20. The high potential pattern 41h and the low potential pattern 41g are located on the side far from the side S2 in the groundless region 43 in the Y direction and are located at the center of the groundless region 43 in the X direction. The low potential pattern 41g has a substantially L shape, and the high potential pattern 41h is formed with a gap at the inner corner of the low potential pattern 41g. Through holes 41a and 41b that conduct with the power connector 20 are formed on the side far from the side S2 of the high potential pattern 41h and the low potential pattern 41g. The through hole 41a is in a conductive state with the power terminal portion 20i (see FIG. 1) of the power connector 20, and the through hole 41b is in a conductive state with the ground terminal portion 20o (see FIG. 1) of the power connector 20.

[0027] As shown in FIG. 8, one solder joint 41c and 41d is formed in each of the high potential pattern 41h and the low potential pattern 41g. The solder joints 41c and 41d form a rectangular shape that is long in the X direction when viewed from the Z direction. The solder joint 41c of the high potential pattern 41h fixes the input terminal 31i (to be described later) of the noise filter element 33 to the high potential pattern 41h in a conductive state. The solder joint 41c is located closer to the side S3 than the central position in the high potential pattern 41h in the Y direction. In this example, it is located at the end on the side S3 of the high potential pattern 41h in the Y direction. Thereby, compared with the configuration in which the solder is formed at the central position in the high potential pattern 41h in the Y direction, the high potential pattern 41h can be formed at a position farther from the ground pattern 45. Therefore, the distance between the high potential pattern 41h and the ground pattern 45 in the Y direction can be ensured. The solder joint 41c is located at the end on the high potential pattern 42h side (the left side in FIG. 8) within the high potential pattern 41h in the X direction.

[0028] The solder joint 41d of the low potential pattern 41g fixes the output terminal 32o (to be described later) of the noise filter element 33 to the low potential pattern 41g in a conductive state. The solder joint 41d is located closer to the high potential pattern 41h than the central position in the low potential pattern 41g in the Y direction. In this example, it is located at the end on the high potential pattern 41h side of the low potential pattern 41g in the Y direction. The solder joint 41d is located at the end on the low potential pattern 42g side (the left side in FIG. 8) within the low potential pattern 41g in the X direction.

[0029] The high potential pattern 41h and the low potential pattern 41g of the conductor layer L4 are formed to be at least separated by a distance D1 from other conductive patterns (for example, the ground pattern 45, the high potential pattern 42h, the low potential pattern 42g, and the control signal pattern 46). The distance D1 is set to a distance at which coupling in which noise or the like is transmitted between the high potential pattern 41h and the low potential pattern 41g and the other conductive patterns is suppressed. The distance D1 is set to be greater than the distance D2, which is the shortest distance between the control signal pattern 46 and the surrounding ground pattern 45. The distance D1 is preferably set to be 2 mm or more, for example. The upper limit value of the distance D1 may be any value, but may be set to 5 mm to 15 mm, for example.

[0030] The high potential pattern 42h and the low potential pattern 42g are formed outside the ground-free region 43 of the conductor layer L4. The high potential pattern 42h is located at least at a distance D1 from the high potential pattern 41h in the X direction. The high potential pattern 42h forms a substantially rectangular shape that is long in the X direction. Three sides of the four sides surrounding the high potential pattern 42h, other than the side on the ground-free region 43 side, are surrounded by the ground pattern 45 including the low potential pattern 42g. The high potential pattern 42h is electrically connected to the control unit 40 via wiring patterns (not shown) of the other conductor layers L1 to L3.

[0031] Solder 42c is formed on the high potential pattern 42h. The solder 42c of the high potential pattern 42h fixes the output terminal 31o (to be described later) of the noise filter element 33 in a state where it is electrically connected to the high potential pattern 42h. The solder 42c is located closer to the side S3 than the central position within the high potential pattern 42h in the Y direction. In this example, it is located at the end on the side S3 side within the high potential pattern 42h in the Y direction. Thereby, the high potential pattern 42h can be formed at a position far from the ground pattern 45, and the distance between the high potential pattern 42h and the ground pattern 45 in the Y direction can be ensured. The solder 42c is located at the end on the high potential pattern 41h side (the right side in FIG. 8) within the high potential pattern 42h in the X direction.

[0032] The low potential pattern 42g is formed as a part of the ground pattern 45 and is located at least at a distance D1 from the low potential pattern 41g in the X direction. The low potential pattern 42g is electrically connected to the control unit 40 via the ground pattern 45. The low-potential pattern 42g is positioned with a gap adjacent to the high-potential pattern 42h in the Y direction. The low-potential pattern 42g is located on the side S2 side of the high-potential pattern 42h.

[0033] Solder 42d is formed on the low-potential pattern 42g. The solder 42d of the low-potential pattern 42g fixes the input terminal 32i (described later) of the noise filter element 33 in a conductive state to the low-potential pattern 42g. The solder 42d is located closer to the high-potential pattern 42h than the central position within the low-potential pattern 42g in the Y direction. In this example, it is located at the end on the high-potential pattern 42h side within the low-potential pattern 42g in the Y direction. The solder 42d is located at the end on the low-potential pattern 41g side (the right side in FIG. 8) within the low-potential pattern 42g in the X direction. The solders 42c and 42d form a rectangular shape that is long in the X direction when viewed from the Z direction.

[0034] As shown in FIG. 8, the noise filter element 33 includes noise filters 31 and 32, a package 35 in the shape of a cube that houses the noise filters 31 and 32, input terminals 31i and 32i, and output terminals 31o and 32o. The input terminals 31i and 32i and the output terminals 31o and 32o are formed as legs extending from the lower surface of the package 35. The input terminal 31i and the output terminal 31o are located at both ends of the noise filter 31 and are arranged in the X direction. The input terminal 32i and the output terminal 32o are located at both ends of the noise filter 32 and are arranged in the X direction.

[0035] The input terminal 31i is fixed in a conductive state to the high-potential pattern 41h by the solder 41c. The input terminal 32i is fixed in a conductive state to the low-potential pattern 42g by the solder 42d. The output terminal 31o is fixed in a conductive state to the high-potential pattern 42h by the solder 42c. The output terminal 32o is fixed in a conductive state to the low-potential pattern 41g by the solder 41d.

[0036] Next, the current path on the circuit board 10 will be described. The current from the power supply terminal portion 20i of the power connector 20 flows in the order of high potential pattern 41h → input terminal 31i → noise filter 31 → output terminal 31o → high potential pattern 42h → wiring pattern (not shown) → control unit 40 → ground pattern 45 (low potential pattern 42g) → input terminal 32i → noise filter 32 → output terminal 32o → low potential pattern 41g → ground terminal portion 20o.

[0037] (Effect) According to the above-described embodiment, the following effects can be obtained. (1) On the circuit board 10, there are mounted a power connector 20 which is an example of a connector to which power from a power supply 5 mounted on a vehicle is input, a control unit 40 that controls the display of the display unit 3 using the power input from the power connector 20 as an operating power supply, and a noise filter element 33 that is electrically connected between the power connector 20 and the control unit 40 and removes noise. The circuit board 10 includes a plurality of conductor layers L1 to L4 arranged in the thickness direction (Z direction) of the circuit board 10. Each of the plurality of conductor layers L1 to L4 includes a ground pattern 45. The ground pattern 45 is a range including a part of the noise filter element 33 as viewed from the Z direction of the circuit board 10 and is formed outside a ground cutout region 43 set at a corner of the circuit board 10. According to this configuration, the ground pattern 45 is not formed in the ground cutout region 43. Therefore, the conductors (ground pattern 45) around the noise filter element 33 can be reduced, and the noise reduction effect by the noise filter element 33 can be enhanced. In particular, since the ground cutout region 43 is set at a corner of the circuit board 10, there are no conductors in two of the four directions around the noise filter element 33 (in FIG. 3, the two directions from the noise filter element 33 toward side S1 and from the noise filter element 33 toward side S2), and the noise reduction effect by the noise filter element 33 can be enhanced.

[0038] (2) The circuit board 10 has a shape in which the corners of a polygon are rounded. The circuit board 10 includes mounting surfaces 10a and 10b on which a plurality of elements 38 different from the noise filter element 33 are mounted. The power connector 20 is provided on or near a side S1 which is an example of a first side of a polygon, closer to a side S2 which is an example of a second side adjacent to the side S1 than to a side S3 which is an example of a third side. The plurality of elements 38 are arranged outside a non-mounting range 44 between the power connector 20 and the side S2 on the mounting surfaces 10a and 10b. According to this configuration, the plurality of elements 38 are not arranged in the non-mounting range 44. Therefore, a wiring pattern which is a conductor is not formed in the non-mounting range 44, and it is possible to suppress an unnecessary increase in the wiring length. As a result, the noise reduction effect by the noise filter element 33 can be enhanced.

[0039] Note that the present disclosure is not limited to the above embodiments and drawings. Modifications (including deletion of components) can be appropriately made without changing the gist of the present disclosure. An example of a modification will be described below.

[0040] (Modification example) In the above embodiment, the control unit 40 that controls the display unit 3 is adopted as the load mounted on the circuit board 10, but the control target of the control unit 40 may be other than the display unit 3. Also, something other than the control unit 40 may be mounted on the circuit board 10 as the load.

[0041] In the above embodiment, either one of the noise filters 31 and 32, for example, the noise filter 32 may be omitted. In this case, the input terminal 32i, the output terminal 32o, and the solders 41d and 42d of the noise filter element 33 are omitted, and the low potential patterns 41g and 42g are continuously connected so as to be electrically conductive. Also in this modification example, since the ground pattern 45 is not formed in the ground-free region 43 of the conductor layers L1 to L3 except for the conductor layer L4, the effect of (1) above can be achieved.

[0042] In the above embodiment, the non-implementation range 44 was set within the ground cutout area 43. However, the present invention is not limited to this, and the ground cutout area 43 and the non-implementation range 44 may be set in the same range, or the ground cutout area 43 may be set within the non-implementation range 44. In the above embodiment, the ground cutout area 43 was set to a range including a part of the noise filter element 33 when viewed from the Z direction. However, the present invention is not limited to this, and the ground cutout area 43 may be set to a range including all of the noise filter element 33. In the above embodiment, any one of the plurality of conductor layers L1 to L4 may be a layer without the ground pattern 45. In the above embodiment, the circuit board 10 had mounting surfaces 10a and 10b on both sides. However, the circuit board 10 may have a mounting surface on only one side. In the above embodiment, the circuit board 10 had a shape in which the corners of the polygon were rounded. However, the circuit board 10 may have a polygonal shape in which the corners are not rounded. In the above embodiment, the circuit board 10 had a rectangular plate shape. However, the circuit board 10 may have other polygonal plate shapes. The positions within the patterns 41h, 42h, 41g, and 42g of the solders 41c, 41d, 42c, and 42d in the above embodiment can be changed as appropriate. For example, the solders 41c, 41d, 42c, and 42d may be provided at substantially the central positions in the Y direction within the respective patterns 41h, 42h, 41g, and 42g. In the above embodiment, the in-vehicle display device 1 may not be mounted on a vehicle.

Description of Reference Numerals

[0043] 1 In-vehicle display device 3 Display unit 4 Control board unit 5 Power supply 10 Circuit board 10a, 10b Mounting surfaces 20 Power connector 20i Power supply terminal portion 20o Ground terminal portion 25 Signal connector 31, 32 Noise filter 31i, 32i input terminals 31o, 32o output terminals 33 noise filter element 35 package 38 element 40 control unit 40i power supply terminal 40o ground terminal 41a, 41b through hole 41c, 41d, 42c, 42d solder 41g, 42g low potential pattern 41h, 42h high potential pattern 43 ground cutout area 44 non - mounting range 45 ground pattern 46 control signal pattern A1, A2 wiring D1, D2 distance L1~L4 conductor layer GND ground If information signal

Claims

1. A connector to which power from a battery mounted on a vehicle is input, a control unit that controls the display of a display device using the power input from the connector as an operating power source, and a circuit board that is electrically connected between the connector and the control unit and on which a noise filter element for reducing noise is mounted, the circuit board including a plurality of conductor layers arranged in the thickness direction of the circuit board, one or more of the plurality of conductor layers including a ground pattern, the ground pattern being a range including at least a part of the noise filter element as viewed from the thickness direction of the circuit board and formed outside a ground cutout region set at a corner of the circuit board, a circuit board.

2. The circuit board has a polygonal shape or a shape in which the corners of the polygonal shape are rounded, the circuit board having a mounting surface on which a plurality of elements different from the noise filter element are mounted, the connector being on or near the first side of the polygonal shape and provided closer to the second side among the second side and the third side adjacent to the first side, the plurality of elements being arranged outside a non-mounting range between the connector and the second side on the mounting surface, The circuit board according to claim 1.

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