Electronic component protection structure and switch device

Abstract

To protect an electronic component from a static electricity charged to a case member with a simple structure.SOLUTION: A ground member 6 with a conductivity is integrally constructed with a circuit board 2 onto which an electronic component 21 is mounted, or is electrically connected to the circuit board 2. The housing comprises a base member 3 and a case member 4, and houses the circuit board 2 and a ground member 6. At least a part of a sealing member 5 as a conductive elastic member arranged between the base member 3 and the case member 4 is exposed to an outside of the casing.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, electronic devices including circuit boards on which electronic components such as ICs are mounted are known. Some of these electronic devices have a protective structure for protecting the electronic components from static electricity.

[0003] For example, the device described in Patent Document 1 improves static electricity resistance by surrounding the entire circumference of the capacitance sensor with a conductive material portion provided on the side wall portion formed by two cases, and by providing an insulating member around the entire circumference at the engaging portion of the two cases.

[0004] Moreover, the device described in Patent Document 2 prevents corona generation by providing a conductive packing for gas sealing between two insulating containers and connecting the packing to the ground potential. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-15202 A [Patent Document 2] Japanese Utility Model Application Publication No. 61-19938 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the device described in Patent Document 1 requires an insulating member. Also, the device described in Patent Document 2 requires the packing to be connected to an external ground terminal. Therefore, there is room for improvement in terms of protecting electronic components from static electricity without complicating the configuration.

[0007] The present technology has an object to protect electronic components from static electricity charged to a case member with a simple configuration. [Means for solving the problem]

[0008] In order to achieve the above object, an electronic component protection structure of the present technology includes a circuit board on which an electronic component is mounted, a conductive ground member that is integral with the circuit board or electrically connected to the circuit board, a housing that includes a base member and a case member and that houses the circuit board and the ground member, and a conductive elastic member that is disposed between the base member and the case member, at least a portion of the conductive elastic member being exposed to the outside of the housing, the conductive elastic member and the ground member are not in contact with each other, The conductive elastic member has an electrical resistance lower than the electrical resistance of both the base member and the case member. Effect of the Invention

[0009] According to the present technology, it is possible to protect electronic components from static electricity charged on a case member with a simple configuration. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a switch device equipped with an electronic component protection structure. [Diagram 2] FIG. 2 is an exploded perspective view of the switch device shown in FIG. [Diagram 3] FIG. 3 is a view seen from the direction of arrow A in FIG. 2. [Figure 4] 3 is a perspective view of a circuit board and a ground member in FIG. 2. [Diagram 5] FIG. 5 is a perspective view of the ground member in FIG. [Figure 6] 2 is a perspective view showing the positional relationship between a circuit board, a case member, and a ground member in the switch device shown in FIG. 1. [Figure 7] 7 is a view seen from the direction of arrow B in FIG. 6. [Figure 8] This is a view of the base member as seen from the +Z side. [Figure 9]FIG. 9 is a cross-sectional view taken along line AA in FIG. [Figure 10] 9 is a cross-sectional view of the switch devices of the first and second modified examples taken along the line AA in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, each embodiment of the present technology will be described in detail with reference to the drawings. However, the configurations described in the following embodiments are merely examples, and the scope of the present technology is not limited by the configurations described in the embodiments. In the following, in each figure, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are assumed (set). The X-axis direction is a direction parallel to the width direction of the switch device. The Y-axis direction is a direction parallel to the depth direction of the switch device. The Z-axis direction is a direction parallel to the height direction of the switch device. In addition, the direction in which the arrow of each axis faces is called the "positive side", and the opposite direction is called the "negative side". In addition, the positive side of the Z-axis direction (+Z side) may be called "up (or upward)", and the negative side of the Z-axis direction (-Z side) may be called "down (or downward)".

[0012] Fig. 1 is a perspective view showing a switch device including an electronic component protection structure according to an embodiment of the present disclosure, Fig. 2 is an exploded perspective view of the switch device.

[0013] A switch device 10 shown in Fig. 1 includes an electronic component protection structure 1, and is used by being installed near the base of a pedal (not shown) for the brake or clutch of an automobile, for example. The switch device 10 is a device that detects the depression of the pedal when the pedal is depressed, and outputs electrically. The switch device 10 may also electrically output the amount of depression. Furthermore, the switch device 10 is not limited to being mounted on an automobile.

[0014] 2, the electronic component protective structure 1 includes a circuit board 2, a base member 3, a case member 4, a sealing member 5, and a ground member 6. The electronic component protective structure 1 protects electronic components 21 on the circuit board 2. The base member 3 and the case member 4 form a housing that houses the circuit board 2 and the ground member 6.

[0015] Furthermore, in addition to the electronic component protection structure 1, the switch device 10 also includes 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, the magnet holder 8, the coil spring 9, and the magnet 11 will be described.

[0016] The rod 7 is a cylindrical member aligned along the Z-axis direction, and is supported so as to be capable of reciprocating in the Z-axis direction. The upper end (tip) 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 semi-spherical shape and abuts against a predetermined member constituting the pedal. When the driver of the automobile depresses the pedal to operate it, the rod 7 moves upward by the biasing force of the coil spring 9. When the driver's depressing force 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. This allows the magnet holder 8 to reciprocate in the Z-axis direction together with the rod 7. The magnet holder 8 is block-shaped and holds a magnet 11 on its Y-axis positive side.

[0017] 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. This allows the rod 7 to be biased upward. An upper end 91 of the coil spring 9 is inserted into a recess 81 of the magnet holder 8, and a lower end 92 of the coil spring 9 is inserted into a protrusion 31 of the base member 3. This restricts the position and attitude of the coil spring 9, allowing the coil spring 9 to stably expand and contract in the Z-axis direction. The relationship between the depression of the pedal and the movement of the rod 7 may be reversed from that in this embodiment.

[0018] Fig. 3 is a view seen from the direction of arrow A in Fig. 2. Fig. 4 is a perspective view of the circuit board 2 and the ground member 6 in Fig. 2. Fig. 5 is a perspective view of the ground member 6 in Fig. 4.

[0019] As shown in FIG. 3, the circuit board 2 is supported by the base member 3 so that the 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 the electronic components 21 include an IC (integrated circuit) and a Hall element. The Hall element is a magnetic sensor that utilizes the Hall effect. When the rod 7 reciprocates with the pedal being depressed, the positional relationship of the Hall element with the magnet 11 held by the magnet holder 8 changes. Due to this change, a voltage generated by the Hall element is detected as the amount of depression of the pedal and is output.

[0020] 4, a plurality of terminals 22 are connected to the circuit board 2. Each of the terminals 22 is electrically connected to a predetermined electronic component 21 via a circuit pattern (not shown). Each of the terminals 22 extends downward as a whole.

[0021] As shown in FIG. 2 and FIG. 3, the base member 3 is a member having a hollow body 32, a pair of claws 34 protruding from the body 32, and a support portion 35 protruding from the body 32 and supporting the circuit board 2, which are integrally formed. The base member 3 is made of various resin materials such as polybutylene terephthalate (PBT). This allows the base member 3 to be easily molded by using a mold when manufacturing the base member 3. The terminals 22 extending from the circuit board 2 are exposed inside the body 32, and the body 32 functions as a connector housing that supports and fixes the terminals 22. An external connector (not shown) can be inserted into the body 32. This allows the terminals of the connector to be electrically connected to the terminals 22.

[0022] A flange portion 33 is formed to protrude from the outer periphery of the body portion 32. A pair of claw portions 34 are formed to protrude upward from the flange portion 33. These claw portions 34 are arranged 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. Note that a protrusion 31 to be inserted into the lower end portion 92 of the coil spring 9 is arranged between the claw portions 34. In addition, a support portion 35 is also formed to protrude upward from the flange portion 33. The support portion 35 holds the circuit board 2 in the X-axis direction. This allows the circuit board 2 to be supported by the base member 3.

[0023] 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 and a cylindrical portion 42 that protrudes cylindrically from the box-shaped portion 41, and is an integrally formed member. Like the base member 3, the case member 4 is made of various resin materials such as polybutylene terephthalate (PBT). This allows the case member 4 to be easily molded by using a mold when manufacturing the case member 4.

[0024] The box-shaped portion 41 has a top plate portion 411 and a side wall portion 412 protruding downward from an edge portion of the top plate portion 411. The side wall portion 412 is provided with engagement portions 43 with which the claw portions 34 of the base member 3 engage. The claw portions 34 engage with the engagement portions 43, whereby the case member 4 is fixed to the base member 3. In addition, a flange portion 44 is formed protruding from the outer periphery of the side wall portion 412.

[0025] Fig. 6 is a perspective view showing the positional relationship between the circuit board 2, the case member 4, and the ground member 6 in the switch device 10. Fig. 7 is a view seen from the direction of arrow B in Fig. 6.

[0026] As shown in FIG. 6 and FIG. 7, the flange portion 44 has a restricting portion 45 protruding downward. 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. As shown in FIG. 1, the cylindrical portion 42 having a tip opening 421 protrudes upward from the top plate portion 411 of the box-shaped portion 41. The rod 7 is slidably supported inside the cylindrical portion 42. As a result, the rod 7 is guided by the cylindrical portion 42 and can reciprocate stably in the Z-axis direction. In addition, a male screw 46 that screws into an attachment (not shown) for the switch device 10 is formed on the outer periphery of the cylindrical portion 42, but this male screw 46 may be omitted.

[0027] As shown in FIG. 2, the sealing member 5 is provided between the base member 3 and the case member 4. The sealing member 5 has a ring shape 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 can be in close contact with the flange portion 33 and the flange portion 44 over its entire circumference, sealing the gap between the base member 3 and the case member 4. That is, the sealing member 5 is elastically sandwiched between the base member 3 and the case member 4. As a result, the waterproofing between the base member 3 and the case member 4 is maintained, and the intrusion of moisture and the like into the case member 4 can be prevented. This prevention of moisture intrusion can protect the circuit board 2. In addition, the restricting portion 45 of the case member 4 (see FIG. 6) 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 neither too much nor too little.

[0028] The sealing member 5 is a conductive elastic member. The sealing member 5 is made of a material having conductivity and elasticity. As an example, the material of the sealing member 5 is an elastic material such as nitrile rubber (NBR) or silicone rubber to which a conductive substance such as carbon or a metal material is added. Note that the material of the conductive elastic member applied to the sealing member 5 is not limited to this example. In addition, the electrical resistance value of the sealing member 5 is lower than the electrical resistance values ​​of both the base member 3 and the case member 4. However, this is not essential.

[0029] As shown in FIG. 4, the ground member 6 is connected to the circuit board 2. The ground member 6 is a ground (GND) line for the circuit board 2, and is made of a conductive material such as a copper alloy. As shown in FIG. 5, the ground member 6 is linear and has a linear portion 61 constituting a main body of the ground member 6, and a protruding portion 62A and a protruding portion 62B protruding from the linear portion 61. The linear portion 61 is bent at multiple points in the middle of its length. The protruding portion 62A branches off from one point in the middle of the length of the linear portion 61 and extends linearly toward the positive side in the X-axis direction. The protruding portion 62B branches off from one point in the middle of the length of the linear portion 61 (the same position as the protruding portion 62A in this embodiment) and extends linearly toward the negative side in the X-axis direction. In this embodiment, the total length of the protruding portion 62B is longer than the total length of the protruding portion 62A. Furthermore, a protruding portion 63 that protrudes toward the negative side in the Y-axis direction branches off from the protruding portion 62B midway in the longitudinal direction, but this protruding portion 63 may be omitted.

[0030] As shown in Fig. 3, at least a tip (part) of each of the protruding portions 62A and 62B is exposed to the inside of the case member 4 as an exposed portion 621. As shown in Figs. 6 and 7, each exposed portion 621 protrudes toward the side wall portion 412 of the case member 4. Note that the terminals 22 are not shown in Figs. 6 and 7. In this embodiment, the exposed portion 621 of the protruding portion 62A protrudes toward the side wall portion 412 of the case member 4 on the positive side in the X-axis direction, and the exposed portion 621 of the protruding portion 62B protrudes toward the side wall portion 412 of the case member 4 on the negative side in the X-axis direction.

[0031] Next, protection of the electronic component 21 by the sealing member 5 will be described.

[0032] Fig. 8 is a view of the base member 3 as seen from the +Z side. Fig. 9 is a cross-sectional view taken along line AA in Fig. 8. In Fig. 8, the terminal 22 is omitted from illustration.

[0033] At least a portion of the sealing member 5 disposed between the base member 3 and the case member 4 is exposed to the outside of the housing formed by the base member 3 and the case member 4. In this embodiment, the sealing member 5 is disposed so as to surround the entire periphery of the circuit board 2 and the ground member 6 when viewed from the Z-axis direction. The sealing member 5 is exposed to the outside around the entire periphery through the gap between the base member 3 and the case member 4, that is, between the opposing surfaces of the base member 3 and the case member 4.

[0034] 8, the shortest distance L3 between the sealing member 5 and the ground member 6 is shorter than the shortest distance L4 between the sealing member 5 and the electronic component 21. In considering the distance between the sealing member 5 and the ground member 6, the ground member 6 may be a conductive member (including a ground pattern or a lightning rod formed on the circuit board 2) that is integral with the circuit board 2 or is electrically connected to the circuit board 2. In the configuration illustrated in FIG. 8, the portion of the ground member 6 closest to the sealing member 5 is the protrusion 62A (or the protrusion 62B).

[0035] On the other hand, when considering the distance between the sealing member 5 and the electronic component 21, if there are multiple electronic components 21, the electronic component 21 that is closest to the sealing member 5 among them.

[0036] According to this embodiment, a circuit board 2 on which an electronic component 21 is mounted and a ground component 6 are housed in a housing made up of a base member 3 and a case member 4. At least a part of a sealing member 5, which is a conductive elastic member arranged between the base member 3 and the case member 4, is exposed to the outside of the housing. This makes it easier for static electricity to be guided to the sealing member 5 from the outside, and makes it difficult for static electricity to be transmitted to the electronic component 21. Furthermore, no insulating member is required to protect the electronic component 21 from static electricity. Moreover, there is no need to connect the sealing member 5 to a ground terminal provided externally. Therefore, the configuration is simpler than in the past.

[0037] Therefore, with a simple configuration, it is possible to protect electronic components 21 from static electricity charged to case member 4. In particular, since sealing member 5 is disposed so as to completely surround circuit board 2 and ground member 6, the effect of protecting electronic components 21 is high.

[0038] Furthermore, since the electrical resistance value of sealing member 5 is lower than that of both base member 3 and case member 4, external static electricity can be more easily conducted to sealing member 5, thereby enhancing protection of electronic component 21.

[0039] Furthermore, the shortest distance L3 between the sealing member 5 and the ground member 6 is shorter than the shortest distance L4 between the sealing member 5 and the electronic component 21. This allows external static electricity to be easily guided to the ground member 6 through the sealing member 5, thereby enhancing the effect of suppressing the transmission of static electricity to the electronic component 21 and enhancing protection of the electronic component 21.

[0040] In addition, since the sealing member 5 is elastically sandwiched between the base member 3 and the case member 4, it has a simple configuration and also functions as a waterproof member. Moreover, since the sealing member 5 is exposed to the outside between the opposing surfaces of the base member 3 and the case member 4, it becomes possible to easily conduct static electricity from the outside while maintaining the waterproof function.

[0041] From the viewpoint of protecting the electronic components 21 from static electricity, it is not essential that the sealing member 5 is arranged so as to surround the entire circumference of the circuit board 2 and the ground member 6 when viewed from the Z-axis direction, and it may have a ring-shaped shape with a partially interrupted portion.

[0042] Note that, when the focus is only on protecting the electronic components 21 from static electricity and sufficient waterproofing is not required, it is not essential that the sealing member 5 be in close contact with the base member 3 and the case member 4 all around. In this case, the sealing member 5 does not need to be called a "sealing member" and may be called a "conductive elastic member".

[0043] It is not essential that the circuit board 2 is supported by the base member 3, but it may be supported by the case member 4 or another member.

[0044] (Modification) In this embodiment, the sealing member 5 and the ground member 6 are separated by at least the shortest distance L3. However, as shown in Fig. 10(a) and (b), the shapes of the sealing member 5 or the ground member 6 may be changed so that the two are in contact with each other.

[0045] Figures 10(a) and (b) are cross-sectional views of the switch devices of the first and second modified examples, taken along a line corresponding to line AA in Figure 8. Figures 10(a) and (b) correspond to Figure 8.

[0046] As shown in a first modified example (FIG. 10(a)), a portion 5x of the sealing member 5 may extend toward the inside of the housing through the gap between the base member 3 and the case member 4 and be in contact with a portion of the exposed portion 621 of the ground member 6.

[0047] Alternatively, as shown in a second modified example (FIG. 10(b)), a portion 621x of the exposed portion 621 of the ground member 6 may extend to the outside of the housing through the gap between the base member 3 and the case member 4 and be in contact with the sealing member 5.

[0048] These modified examples contribute to preferential discharge from the case member 4 to the exposed portion 621. Therefore, external static electricity can be more easily guided from the sealing member 5 to the ground member 6, thereby enhancing protection of the electronic component 21. Note that a configuration may also be adopted in which a part of the sealing member 5 and a part of the exposed portion 621 extend in directions facing each other, and the base member 3 and the case member 4 come into contact with each other in a gap between them.

[0049] Although the preferred embodiments of the present technology have been described above, the present technology is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the technology. Note that, although the electronic component protection structure 1 is applied to the switch device 10 in the present embodiment, the application is not limited to the switch device 10, and the electronic component protection structure 1 can be applied to various electronic devices. [Explanation of symbols]

[0050] 1 electronic component protection structure, 2 circuit board, 3 base member, 4 case member, 5 sealing member, 6 ground member, 21 electronic component, L3, L4 shortest distance

Claims

1. A circuit board on which electronic components are mounted; a conductive ground member that is integral with the circuit board or that is electrically connected to the circuit board; a housing including a base member and a case member, the housing housing the circuit board and the ground member; a conductive elastic member disposed between the base member and the case member, At least a portion of the conductive elastic member is exposed to the outside of the housing, the conductive elastic member and the ground member are not in contact with each other, An electronic component protection structure, wherein the conductive elastic member has an electrical resistance value lower than both the electrical resistance values ​​of the base member and the case member.

2. 2. The electronic component protection structure according to claim 1, wherein the shortest distance between the conductive elastic member and the ground member is shorter than the shortest distance between the conductive elastic member and the electronic component.

3. 2. The electronic component protection structure according to claim 1, wherein the conductive elastic member is disposed so as to completely surround the circuit board and the ground member.

4. The electronic component protection structure according to claim 3 , wherein the conductive elastic member is elastically sandwiched between the base member and the case member.

5. 5. The electronic component protection structure according to claim 4, wherein the conductive elastic member is exposed to the outside between the opposing surfaces of the base member and the case member.

6. A switch device comprising the electronic component protection structure according to claim 1 .

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