Electronic component protection structure and switch device

Abstract

To provide an electronic component protection structure and a switch device that has a simple configuration and can protect the electronic component from static electricity charged in a case member.SOLUTION: An electronic component protection structure 1 includes a circuit board 2 on which an electronic component 21 is mounted, a base member 3 that supports the circuit board 2, a case member 4 that covers the circuit board 2 and is fixed to the base member 3, and a conductive ground member 6 connected to the circuit board 2, and the ground member 6 includes an exposed portion 621 that is at least partially exposed inside the case member 4.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an electronic component protection structure and a switch device.

Background Art

[0002] Conventionally, electronic devices including a circuit board on which electronic components such as ICs are mounted are known. Some of these electronic devices have a protection structure for protecting the electronic components from static electricity. As an example of a device having a protection structure, Patent Document 1 discloses a device including an electric motor housing to which a circuit board (control board) is fixed and a control unit cover covering the circuit board. In the device described in Patent Document 1, the control unit cover is fixed to the electric motor housing by fastening a fixing bolt to an insert nut molded in the electric motor housing. Further, a ground terminal forming body is molded in the electric motor housing, and a cover ground terminal of the ground terminal forming body is electrically connected to the fixing bolt via the insert nut. When static electricity is charged on the control unit cover, the static electricity can be discharged to the vehicle body through the fixing bolt, the insert nut, and the ground terminal forming body in sequence. Patent Document 2 discloses a device including an operation unit as a membrane switch and a circuit board having a connector to which the operation unit is connected. In the device described in Patent Document 2, a static electricity grounding pattern electrically connected to a terminal of the connector is formed on the circuit board. Then, the static electricity of the operation unit can be discharged through this static electricity grounding pattern.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the device described in Patent Document 1 has a protective structure that includes fixing bolts, insert nuts, and a grounding terminal forming body, resulting in a relatively large number of parts. Furthermore, the shape of the grounding terminal forming body tends to be complex. In the device described in Patent Document 2, the circuit board tends to be larger and more complex because a pattern for electrostatic grounding is formed on the circuit board.

[0005] The present invention aims to provide an electronic component protection structure and a switch device that can protect electronic components from static electricity charged on a case member with a simple configuration. [Means for solving the problem]

[0006] To achieve the above objective, the electronic component protection structure of the present invention comprises a circuit board on which electronic components are mounted, a base member that supports the circuit board, a case member that covers the circuit board and is fixed to the base member, and a conductive ground member connected to the circuit board, wherein the ground member is It has a linear portion and a protruding portion that branches off from the middle of the linear portion in the longitudinal direction, and at least the tip of the protruding portion is Exposed portion exposed on the inside of the case member As a result, the exposed portion protrudes toward the case member. [Effects of the Invention]

[0007] According to the present invention, electronic components can be protected from static electricity charged on the case member with a simple configuration. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing a switch device equipped with an electronic component protection structure according to a first embodiment of the present invention. [Figure 2] Figure 1 is an exploded perspective view of the switch device shown. [Figure 3] This is a view from the direction of arrow A in Figure 2. [Figure 4] Figure 2 is a perspective view of the circuit board and ground member. [Figure 5] This is a perspective view of the ground member in Figure 4. [Figure 6] Figure 1 is a perspective view showing the positional relationship between the circuit board, case member, and ground member in the switch device shown. [Figure 7] This is a view from the direction of arrow B in Figure 6. [Figure 8] This is an exploded perspective view showing a switch device equipped with an electronic component protection structure according to a second embodiment of the present invention. [Figure 9] Figure 8 is a schematic cross-sectional view showing the positional relationship between the case member and the ground member in the switch device. [Figure 10] This is a schematic cross-sectional view showing the positional relationship between the case member and the ground member in the electronic component protection structure of the third embodiment of the present invention. [Figure 11] This is a schematic cross-sectional view showing a modified example of the electronic component protection structure of the third embodiment. [Modes for carrying out the invention]

[0009] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the configurations described in the following embodiments are merely illustrative, and the scope of the present invention is not limited by the configurations described in each embodiment. In the following, the X, Y, and Z axes are assumed to be mutually orthogonal in each figure. The X-axis direction is parallel to the width direction of the switch device. The Y-axis direction is parallel to the depth direction of the switch device. The Z-axis direction is parallel to the height direction of the switch device. The direction in which the arrows of each axis point is referred to as the "positive side," and the opposite direction is referred to as the "negative side." The positive side of the Z-axis direction may also be referred to as "up (or upward)," and the negative side of the Z-axis direction may be referred to as "down (or downward)."

[0010] <First Embodiment> The first embodiment will be described below with reference to Figures 1 to 7. The switch device 10 shown in Figure 1 is equipped with an electronic component protection structure 1 and is used by being installed, for example, near the base of a pedal (not shown) such as a brake or clutch pedal in an automobile. The switch device 10 is a device that detects when the pedal is pressed down and outputs an electrical signal. The switch device 10 may also output an electrical signal of the amount of pedal press. Furthermore, the switch device 10 is not limited to being mounted in an automobile.

[0011] As shown in Figure 2, the electronic component protection structure 1 comprises a circuit board 2, a base member 3, a case member 4, a sealing member 5, and a ground member 6. In addition to the electronic component protection structure 1, the switch device 10 comprises a rod 7, a magnet holder 8, a coil spring 9, and a magnet 11. Before describing the electronic component protection structure 1, the rod 7, magnet holder 8, coil spring 9, and magnet 11 will be described.

[0012] The rod 7 is a cylindrical member along the Z-axis direction and is supported so as to be reciprocable in the Z-axis direction. The upper end portion (tip portion) of the rod 7 protrudes from the tip opening 421 of the case member 4 (see FIG. 1). The upper end surface 71 of the rod 7 is rounded in a hemispherical shape and abuts against a predetermined member constituting the pedal. Then, when the driver of the vehicle steps on and operates this pedal, the rod 7 moves upward by the biasing force of the coil spring 9. Further, when the stepping force from the driver is released, the rod 7 is pressed downward against the biasing force of the coil spring 9. A magnet holder 8 is disposed below the rod 7. Thereby, the magnet holder 8 can reciprocate in the Z-axis direction together with the rod 7. The magnet holder 8 has a block shape and holds a magnet 11 on the positive side in the Y-axis direction. A coil spring 9 is disposed below the magnet holder 8. The coil spring 9 is in a compressed state between the magnet holder 8 and the base member 3. Thereby, the rod 7 can be biased upward. Further, the upper end portion 91 of the coil spring 9 is inserted into the concave portion 81 of the magnet holder 8, and the convex portion 31 of the base member 3 is inserted into the lower end portion 92 of the coil spring 9. Thereby, the position and posture of the coil spring 9 are regulated, and the coil spring 9 can stably expand and contract in the Z-axis direction. Note that the relationship between the depression of the pedal and the movement of the rod 7 may be a reversed relationship with respect to the relationship in the present embodiment.

[0013] The electronic component protection structure 1 includes a circuit board 2, a base member 3, a case member 4, a sealing member 5, and a ground member 6, and protects the electronic component 21 of the circuit board 2.

[0014] As shown in Figure 3, the circuit board 2 is supported by the base member 3 such that its thickness direction is parallel to the Y-axis direction. One or more electronic components 21 are mounted on at least one surface of the circuit board 2. Examples of electronic components 21 include ICs (integrated circuits) and Hall elements. A Hall element is a magnetic sensor that utilizes the Hall effect. As the pedal is pressed, the rod 7 reciprocates, changing the positional relationship between the Hall element and the magnet 11 held in the magnet holder 8. This change causes a voltage generated in the Hall element, which is detected as the amount of pedal depression and output. As shown in Figure 4, the circuit board 2 has multiple terminals 22 connected to it. Each terminal 22 is electrically connected to a predetermined electronic component 21 via a circuit pattern (not shown). Each terminal 22 extends downward as a whole.

[0015] As shown in Figures 2 and 3, the base member 3 has a hollow body portion 32, a pair of claw portions 34 protruding from the body portion 32, and a support portion 35 protruding from the body portion 32 to support the circuit board 2, and these are integrally formed members. The base member 3 is made of various resin materials such as polybutylene terephthalate (PBT). This makes it possible to easily mold the base member 3 by using a mold when manufacturing the base member 3. The body portion 32 has terminals 22 extending from the circuit board 2 exposed on its inside, and functions as a connector housing that supports and fixes each terminal 22. An external connector (not shown) can be inserted into this body portion 32. This electrically connects the terminals of the connector to each terminal 22. A flange portion 33 is formed protruding from the outer circumference of the body portion 32. A pair of claw portions 34 are formed protruding upward from this flange portion 33. These claw portions 34 are spaced apart in the X-axis direction and engage with the case member 4 from the outside. This allows the case member 4 to be fixed to the base member 3. A protrusion 31, which is inserted into the lower end 92 of the coil spring 9, is positioned between the claw portions 34. In addition, a support portion 35 is formed to protrude upward from the flange portion 33. The support portion 35 clamps the circuit board 2 in the X-axis direction. As a result, the circuit board 2 is supported by the base member 3.

[0016] As shown in FIGS. 1 and 2, the case member 4 is a member that is disposed above the base member 3 and covers the circuit board 2. The case member 4 has a box-shaped portion 41 having a box shape and a cylindrical portion 42 protruding from the box-shaped portion 41 in a cylindrical shape, and these are integrally formed members. The case member 4 is made of various resin materials such as polybutylene terephthalate (PBT), similar to the base member 3. Thereby, when manufacturing the case member 4, the case member 4 can be easily molded rather than using a mold. Note that the case member 4 may be made of various metal materials such as stainless steel. The box-shaped portion 41 has a top plate portion 411 and side wall portions 412 protruding downward from the edge of the top plate portion 411. The side wall portions 412 are provided with engaging portions 43 with which the respective claw portions 34 of the base member 3 engage. When the claw portions 34 engage with the engaging portions 43, the case member 4 is fixed to the base member 3. Further, a flange portion 44 protrudes from the outer peripheral portion of the side wall portion 412. As shown in FIGS. 6 and 7, a restricting portion 45 protrudes downward from the flange portion 44. The restricting portion 45 is formed in a ring shape along the circumferential direction of the side wall portion 412, and is a portion that restricts the compression limit when the sealing member 5 is compressed between the flange portion 33 of the base member 3 and the flange portion 44 of the case member 4. A cylindrical portion 42 having a tip opening portion 421 protrudes upward from the top plate portion 411 of the box-shaped portion 41. A rod 7 is slidably supported inside the cylindrical portion 42. Thereby, the rod 7 is guided by the cylindrical portion 42 and can stably reciprocate in the Z-axis direction. Note that a male screw 46 that engages with an attachment (not shown) for the switch device 10 is formed on the outer peripheral portion of the cylindrical portion 42, but this male screw 46 may be omitted.

[0017] As shown in Figure 2, a sealing member 5 is provided between the base member 3 and the case member 4. The sealing member 5 is ring-shaped, similar to the restricting portion 45 of the case member 4, and is compressed between the flange portion 33 of the base member 3 and the flange portion 44 of the case member 4, as described above. As a result, the sealing member 5 adheres tightly to the flange portion 33 and the flange portion 44 around its entire circumference, sealing the space between the base member 3 and the case member 4. This maintains waterproofness between the base member 3 and the case member 4, preventing moisture from entering the case member 4. This prevention of moisture intrusion protects the circuit board 2. The restricting portion 45 of the case member 4 is located inside the ring-shaped sealing member 5. The compression limit of the sealing member 5 is restricted by the restricting portion 45 of the case member 4. As a result, the sealing member 5 is compressed without excess or deficiency. The sealing member 5 is made of various rubber materials, such as nitrile rubber, urethane rubber, silicone rubber, or fluororubber.

[0018] As shown in Figure 4, a ground member 6 is connected to the circuit board 2. The ground member 6 is a ground (GND) wire to the circuit board 2 and is made of a conductive material such as a copper alloy. As shown in Figure 5, the ground member 6 is linear and has a linear portion 61 that constitutes the main body of the ground member 6, and protrusions 62A and 62B that protrude from the linear portion 61. The linear portion 61 is bent at multiple points along its longitudinal direction. Protrusion 62A branches off from one point along the longitudinal direction of the linear portion 61 and extends linearly toward the positive X-axis direction. Protrusion 62B branches off from one point along the longitudinal direction of the linear portion 61 (the same position as protrusion 62A in this embodiment) and extends linearly toward the negative X-axis direction. In this embodiment, the total length of protrusion 62B is longer than the total length of protrusion 62A. Furthermore, a projection 63 branches off from the middle of the longitudinal direction of the projection 62B, projecting in the negative direction in the Y-axis direction, but this projection 63 may be omitted.

[0019] As shown in Figure 3, the protrusions 62A and 62B each have exposed portions 621, at least their tips (parts) exposed to the inside of the case member 4. As shown in Figures 6 and 7, each exposed portion 621 protrudes toward the side wall portion 412 of the case member 4. Note that in Figures 6 and 7, the terminal 22 is omitted from the circuit board 2. In this embodiment, the exposed portion 621 of protrusion 62A protrudes toward the side wall portion 412 of the case member 4 in the positive X-axis direction, and the exposed portion 621 of protrusion 62B protrudes toward the side wall portion 412 of the case member 4 in the negative X-axis direction. This protrusion makes the shortest distance L1 between each exposed portion 621 and the side wall portion 412 of the case member 4 smaller than the shortest distance L2 between the circuit board 2 including the electronic component 21 and the side wall portion 412 of the case member 4 (see Figure 7). As a result, when the case member 4 becomes charged, discharge from the case member 4 to the exposed part 621 takes precedence over discharge from the case member 4 to the circuit board 2, thereby protecting the electronic components 21 from static electricity. Causes of static electricity include, for example, a driver's feet rubbing against the floor mat inside a car, or the worker becoming charged when installing or replacing the switch device 10.

[0020] As described above, the switch device 10 (electronic component protection structure 1) has a simple configuration in which at least a portion of the ground member 6 is exposed to the inside of the case member 4, thereby protecting the electronic component 21 from static electricity charged on the case member 4. Furthermore, it is possible to omit the provision of a discharge member for the case member 4 in addition to the ground member 6. This makes it possible to suppress an increase in the number of components constituting the switch device 10 and an increase in the size of the switch device 10. In addition, the protrusion 62B is positioned on the opposite side of the protrusion 62A from the linear portion 61. As a result, the ground member 6 has two exposed portions 621 on both sides of the linear portion 61, which increases the number of discharge points from the case member 4 to the ground member 6. In addition, each exposed portion 621 is spaced apart from the side wall portion 412 of the case member 4. As a result, each exposed portion 621 is prevented from hindering the compression of the sealing member 5, and thus the sealing member 5 can fully perform its waterproof function.

[0021] <Second Embodiment> The second embodiment will now be described with reference to Figures 8 and 9. As shown in Figure 8, the switch device 10 (electronic component protection structure 1) of this embodiment differs from the switch device 10 (electronic component protection structure 1) of the first embodiment in that the sealing member 5 is omitted. Such a switch device 10 can be used when waterproofing is not required. Also, when waterproofing is not required, as shown in Figure 9, the exposed portion 621 of the protruding portion 62A of the ground member 6 may be in contact with the side wall portion 412 of the case member 4 (the same applies to the exposed portion 621 of the protruding portion 62B). This is because each exposed portion 621 does not hinder the compression of the sealing member 5. Furthermore, when each exposed portion 621 is in contact with the side wall portion 412, when the case member 4 becomes charged, discharge from the case member 4 to the exposed portion 621 takes precedence over discharge from the case member 4 to the circuit board 2. This allows for more adequate protection of the electronic component 21 from static electricity. Each exposed portion 621 may be in contact with the side wall portion 412, penetrate the side wall portion 412, and protrude outward. Furthermore, each exposed portion 621 is not limited to being in contact with the side wall portion 412, but may be spaced apart from the side wall portion 412, as in the first embodiment.

[0022] <Third Embodiment> The third embodiment will now be described with reference to Figure 10. As shown in Figure 10, in this embodiment, the case member 4 has a case-side projection 47 on the side wall portion 412 that protrudes toward the exposed portion 621 of the projection 62A (the same applies to the projection 62B side). Each case-side projection 47 is spaced apart from the exposed portion 621. Furthermore, the configuration of this embodiment can be applied to the switch device 10 (electronic component protection structure 1) of the first and second embodiments. This makes it possible to reduce the distance to the exposed portion 621 compared to the distance in the first and second embodiments, contributing to preferential discharge from the case member 4 to the exposed portion 621.

[0023] <Variation> Hereinafter, a modified example of the third embodiment will be described with reference to Figure 11. As shown in Figure 11, in this embodiment, the case-side protrusion 47 is in contact with the exposed portion 621. The configuration of this modified example can be applied to the switch device 10 (electronic component protection structure 1) of the first and second embodiments. This allows the distance to the exposed portion 621 to be further reduced, contributing to more preferential discharge from the case member 4 to the exposed portion 621. Furthermore, even when the configuration of this modified example is applied to the switch device 10 of the first embodiment, the case member 4 contacting the exposed portion 621 via the case-side protrusion 47 prevents the exposed portion 621 from hindering the compression of the sealing member 5.

[0024] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of its gist. In this embodiment, the electronic component protection structure 1 is shown as being applied to a switch device 10 as an example, but the application is not limited to the switch device 10 and can be applied to various electronic devices. [Explanation of Symbols]

[0025] 1. Electronic component protection structure 2 Circuit boards 21 Electronic Components 3 Base member 4 Case components 5 Sealing member 6. Ground members 621 Exposed part 10 Switching device

Claims

1. A circuit board on which electronic components are mounted, A base member that supports the circuit board, A case member that covers the circuit board and is fixed to the base member, The circuit board is connected to a conductive ground member, and comprises The ground member has a linear portion that is linear in shape, and a protruding portion that branches off from the middle of the linear portion in the longitudinal direction, The aforementioned protruding portion, at least its tip, becomes an exposed portion that is exposed to the inside of the case member. The exposed portion is an electronic component protection structure that protrudes toward the case member.

2. The electronic component protection structure according to claim 1, wherein the protruding portion is also arranged on the opposite side from the linear portion.

3. The electronic component protection structure according to claim 1, wherein the shortest distance between the exposed portion and the case member is smaller than the shortest distance between the circuit board and the case member.

4. The exposed portion is spaced apart from the case member, as described in claim 3, for the electronic component protection structure.

5. The exposed portion is in contact with the case member, as described in claim 3.

6. The electronic component protection structure according to claim 4, further comprising a sealing member provided between the base member and the case member to seal the space between them.

7. The electronic component protection structure according to claim 1, wherein the case member has a case-side protrusion that protrudes toward the exposed portion.

8. The electronic component protection structure according to claim 1, wherein the case member is made of a resin material.

9. A switch device comprising the electronic component protection structure described in claim 1.

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