JP2006222341A - Fixing structure for constitution member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing structure for a constitution member, such as a circuit substrate, metallic base plate or the like, which is capable of simply reducing radiation noise at a low cost, and to provide a noise reducing method. <P>SOLUTION: The constitution member consisting of circuit substrates 6, 7 or a metallic base plates 8 is fixed to a fixing body 2 through fixing members 9 (20, 21, 21', 21", 22, 22', 22"), and at least either one of the material or the configuration of the fixing members 9 (20, 21, 21', 21", 22, 22', 22") is changed whereby either connecting or insulating electrically a grounding land 16, provided on the constitution members, 6, 7, 8, to the fixing body 2 is permitted to be selected and noise characteristics are changed by changing a grounding position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing structure for constituent members such as a circuit board and a metal base plate.

  Electric and electronic devices emit unintended electromagnetic waves (noise) to the outside during use. Such radiation noise is known to cause other devices to malfunction, and this phenomenon is called EMI (Electromagnetic Interference). Various regulations are set for radiation noise of electric and electronic equipment, and an information technology device such as a personal computer has an international standard called CISPR22. In Japan, a limit value by a voluntary regulation of VCCI is set.

Conventionally, in order to suppress EMI noise, noise generated by reducing ground resistance by reinforcing ground connection of a circuit board is reduced, or a circuit is covered with metal as described in Patent Document 1. It is common to prevent noise from leaking outside by electromagnetic shielding.
Japanese Patent Laid-Open No. 10-145071

  However, portable information devices such as digital cameras have been downsized, and it has become difficult to sufficiently cover the circuit with a metal cover or metal housing in order to shield noise, and noise reduction due to grounding has become important. ing.

  In general, noise is less likely to occur when the grounding resistance is lower, but depending on the circuit configuration, noise may increase if the grounding location is wrong. This is not simply a matter of simply increasing the grounding. It is difficult to predict the magnitude of noise generated at the design stage, and it is necessary to make a prototype of the product, measure the radiated noise, and redesign if the radiated noise exceeds the reference value. In particular, changing the shape of the metal casing or metal base plate that becomes the ground has a problem of requiring much time and cost.

  Also, as a simple method of reducing radiation noise, a method of sticking a metal sheet is known, but this not only increases the manufacturing cost, but also reliably reduces noise due to large variations during assembly. I can't.

  In view of the above problems, it is an object of the present invention to provide a fixing structure for a component member such as a circuit board or a metal base plate and a noise reduction method that can easily reduce radiation noise at low cost.

  In order to solve the above-described problem, a first aspect of the present invention is to fix a constituent member made of a circuit board or a metal base plate to a fixed body with a fixing member, and change at least one of the material and shape of the fixing member. By doing so, there is provided a fixing structure for the constituent member capable of selecting whether the grounding land provided on the constituent member is electrically connected to or insulated from the fixed body. The metal base plate as used herein refers to all metallic members provided for shields and structures, and also includes a metal casing. Further, the fixed body means an object to fix the constituent member, and may be not only the housing but also a circuit board, another metal base plate, or any other constituent element. Further, the ground land may be provided on the entire surface of the component member, and the metal component member can be understood to be the ground land.

  According to this structure, when fixing a structural member with respect to a fixed body with a fixing member, it can be selected whether a structural member and a fixed body are electrically connected by the shape and material of a fixing member. As a result, it is possible to reduce the noise by changing the grounding position without changing the design, simply by replacing the fixing member with one having a different shape or material.

  According to a second aspect of the present invention, a plurality of constituent members made of a circuit board or a metal base plate are fixed to each other or to a fixed body with a fixing member with a gap, and the constituent members are grounded. A land is provided, and by changing at least one of the material and shape of the fixing member, the ground lands are electrically connected to each other and between the ground lands and the fixed body or insulated. There is provided a fixing structure of a component member which can be selected.

  According to this configuration, it is possible to change the grounding position by selecting whether or not the two constituent members are electrically connected to each other or to the fixed member, and it is possible to reduce noise without changing the design.

  In the first and second aspects of the present invention, the component member may be provided with a plurality of fixing holes for fixing with the fixing member, and a grounding land surrounding the fixing hole.

  According to this configuration, the grounding lands of the constituent members can be selectively grounded via the fixing screws and washers, and noise can be reduced without changing the design.

  According to a third aspect of the present invention, there is provided a fixing structure for fixing two constituent members made of a circuit board or a metal base plate to each other with a gap or both to a fixed body, wherein the constituent members are Is provided with a fixing hole penetrating the thickness, and a grounding land surrounding the fixing hole, and a fixing screw penetrating the fixing holes of the two constituent members, and penetrating the fixing screw. A spacer that is sandwiched between the spacers to define the distance between them, and a washer that is sandwiched between the component member and the fixed body, or between the component member and the head of the fixing screw, and penetrates the fixing screw. A fixing structure for fixing the two constituent members is provided.

  According to this configuration, whether or not the structural members are electrically connected to each other depending on the shape and material of the spacer, and whether the structural member is grounded to the fixed body directly or via a fixing screw depending on the material of the washer. You can choose whether or not. As a result, it is possible to reduce noise by individually selecting whether or not to ground each ground land without changing the design and changing the ground position. In addition, the washer can be omitted when the grounding land is electrically connected to the fixing screw or the fixing body. In this case, however, it is understood that the head of the fixing screw or the contact portion of the fixing body is integral with the washer. And can be equated with using a conductive washer.

  Further, in the third aspect of the present invention, at least one of the spacer and the washer may have a bush portion that is fitted into the fixing hole and prevents the fixing screw and the fixing hole from directly contacting each other. The grounding land may be provided so as to surround the fixing hole at a distance.

  According to this configuration, it is possible to prevent unintended grounding from occurring due to the fixing screw directly contacting the ground land.

  Moreover, the 3rd aspect of this invention WHEREIN: The said contact land may be provided in both surfaces of the said structural member.

  According to this configuration, the electrically connected path can be set on either side of the constituent member, so that the ground path can be easily selected.

  Further, a fourth aspect of the present invention is a fixing structure for fixing a plurality of constituent members made of a circuit board or a metal base plate to each other or a fixed body with a gap, wherein the constituent members are: Fixing holes each penetrating the thickness are provided, and at least one of the constituent members is provided so that relay lands electrically connected to each other by through holes on both sides surround the periphery of the fixing holes, and the relay is provided on at least one side. A ground land is provided so as to surround the land, and the relay land is electrically connected to each other through a conductive spacer sandwiched between two adjacent constituent members, and passes through the fixing hole. Via at least one of a fixing screw and a conductive washer sandwiched between the component member and the fixed body or between the head of the fixing screw and the component member The washer or the spacer is electrically connected to the fixed body, and the grounding land is electrically connected to or insulated from the relay land by changing at least one of its shape and partial material. There is provided a fixing structure of a component member that can be selected.

  According to this configuration, the relay lands of the plurality of constituent members are electrically connected to each other with the conductive spacers and grounded, and the material or shape of the spacer or the washer is selected, so that each ground land is used as the relay land. Whether or not to connect can be individually determined. As a result, the noise can be reduced by changing the grounding position without changing the design.

  According to a fifth aspect of the present invention, in a fixing structure in which a constituent member made of a circuit board or a metal base plate is fixed to a fixing body with a fixing member, at least one of the material and shape of the fixing member is changed. The grounding lands provided on the component members can be selected to be electrically connected or insulated with respect to the fixed body, and the noise characteristics are changed by changing the grounding position by changing the material of the fixing member. A noise reduction method is provided.

  According to this method, it is possible to reduce the noise by changing the grounding position without changing the design, simply by replacing the fixing member with one having a different shape or material.

  According to a sixth aspect of the present invention, there is provided a fixing structure in which a plurality of constituent members made of a circuit board or a metal base plate are fixed to each other or to a fixed body with a fixing member with a gap therebetween. The grounding lands are provided, and at least one of the material and shape of the fixing member is changed to electrically connect or insulate the grounding lands to each other and between the grounding lands and the fixed body. There is provided a noise reduction method for changing noise characteristics by changing at least one of a material and a shape of the fixing member.

  According to this method, it is possible to change the grounding position by selecting whether or not the two constituent members are electrically connected to each other or to the fixed member, and it is possible to reduce noise without changing the design.

  In the fifth and sixth aspects of the present invention, the component member may be provided with a plurality of fixing holes for fixing with the fixing member, and a grounding land surrounding the fixing hole.

  According to this configuration, the ground land of the ground line of the constituent member can be selectively grounded via the fixing screw or the washer, and noise can be reduced without changing the design.

  Further, according to a seventh aspect of the present invention, in the fixing structure in which two constituent members made of a circuit board or a metal base plate are fixed to each other with a gap, or both to a fixed body, A fixing hole penetrating the thickness and a grounding land surrounding the fixing hole are provided, a fixing screw penetrating the fixing hole of the two constituent members together, and penetrating the fixing screw and sandwiched between the constituent members The two members are defined by a spacer that defines the distance between the two, the component member and the fixing body, and a washer that is sandwiched between the component member and the head of the fixing screw and penetrates the fixing screw. By fixing the constituent members and changing the shape and / or the material of at least one of the spacer and the washer, the ground lands of the constituent members can be connected to each other and each of the grounding rollers. Between de and the fixed body, and select whether to insulating or electrically connected, to provide a noise reduction method of changing the noise characteristic by changing the grounding positions.

  According to this method, it is possible to select whether or not the ground lands of the constituent members and the ground lands are grounded with respect to the fixed body according to the shape and material of the spacer and the washer. As a result, the noise can be reduced by changing the grounding position without changing the design.

  Further, in the seventh aspect of the present invention, at least one of the spacer and the washer may have a bushing portion that is fitted into the fixing hole and prevents the fixing screw and the fixing hole from directly contacting each other. The grounding land may be provided so as to surround the fixing hole at a distance.

  According to this method, it is possible to prevent the fixing screw from directly contacting the ground land and unintentionally grounding.

  Moreover, the 7th aspect of this invention WHEREIN: The said grounding land may be provided in both surfaces of the said structural member.

  According to this method, the electrically connected path can be set on either side of the constituent member, so that the ground path can be easily selected.

  According to an eighth aspect of the present invention, there is provided a fixing structure in which a plurality of constituent members made of a circuit board or a metal base plate are fixed to each other or to a fixed body with a gap therebetween. A fixing hole penetrating the fixing hole is provided on at least one of the component members so as to surround the fixing hole, and the relay land is surrounded on at least one side. A grounding land, and the relay land is electrically connected to each other via a conductive spacer sandwiched between two adjacent components, and a fixing screw penetrating the fixing hole; The fixing member is connected to the fixing member via at least one of a conductive washer sandwiched between the component member and the fixing member or between the head of the fixing screw and the component member. Noise characteristics by selecting whether to electrically connect or insulate the ground land to the relay land by changing at least one of the shape and partial material of the washer or the spacer Provided is a noise reduction method for changing the frequency.

  According to this method, the relay lands are electrically connected to each other by the conductive spacer, and by selecting the material and shape of the screw head, spacer, or washer, whether or not each ground land is connected to the relay land. Can be determined individually, and noise can be reduced by changing the grounding position without changing the design.

  As described above, according to the present invention, the constituent members can be fixed and simultaneously electrically connected or insulated. Thereby, the noise characteristic can be changed by changing the grounding state of the fixed portion of the component member, and the noise can be reduced at a low cost without a design change.

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a digital camera 1 according to a first embodiment of the present invention, in which noise is reduced by a structural member fixing structure of the present invention. The digital camera 1 has a lens unit 3 mounted on the front surface of a metal housing 2. The lens unit 3 includes a plurality of lenses 4 and an image sensor 5 and converts an image into an electrical signal. In the digital camera 1, the first substrate 6, the second substrate 7, and the metal base plate 8 are fixed to the metal housing 2 by a plurality of fixing members 9 inside the metal housing (fixed body) 2. Yes. The first board 6 and the second board 7 are connected by a connector 10, and the second board 7 is provided with a button 11 operated by a user. A liquid crystal display device 12 is disposed on the back surface of the metal base plate 8. The digital camera 1 houses a battery 13.

  FIG. 2 shows the first substrate 6, the second substrate 7 and the metal base plate 8. The first substrate 6 and the second substrate 7 are printed circuit boards on which a metal layer is printed. The second substrate 7 and the metal base plate 8 are fixed to the back side of the first substrate 6 with a gap by a fixing member 9. On the back side of the first substrate 6 and the second substrate 7, a ground line 14 connected to the ground of each circuit is provided as a printed circuit so as to connect a part or all of the portion where the fixing member 9 is disposed. It has been.

  FIG. 3 shows the back surfaces of the first substrate 6 and the second substrate 7. Each of the first substrate 6 and the second substrate 7 is provided with a large number of fixing holes 15 for attaching the fixing members 9. When the fixing holes 15 are on the ground line 14, grounding is performed so as to surround the fixing holes 15. A ground land 16 extending from the line 14 is provided. In the present embodiment, as illustrated, five ground lands 16 are provided on the first substrate 6, and six ground lands 16 are provided on the second substrate 7. A power IC 17 having a ground connected to the ground line 14 is attached to the first substrate 6.

  Further, FIG. 4 shows in detail the fixing structure of the present embodiment in which the first substrate 6 and the second substrate 7 are fixed to the metal housing 2 by the fixing member 9. The first substrate 6 and the second substrate 7 are provided with ground lines 14 made of metal layers connected to each other by through holes (not shown) on both surfaces, and ground lands 16 are formed on both surfaces around the fixing hole 15. ing. The 1st board | substrate 6 and the 2nd board | substrate 7 are fixed to the protrusion part 18 from which the metal housing | casing 2 protruded inside. The fixing member 9 is sandwiched between a metal fixing screw 20 that passes through the fixing hole 15 and is screwed into a screw hole 19 provided in the protrusion 18, and a head 20 a of the fixing screw 20 and the second substrate 7. The conductive metal washer 21 penetrated through the screw portion 20b of the fixing screw 20 and the screw portion 20b of the fixing screw 20 are sandwiched between the first substrate 6 and the second substrate 7 so that the distance between them is increased. The conductive metal spacer 22 is defined, and the metal washer 21 is inserted between the metal housing 2 and the first substrate 6 and penetrates through the screw portion 20 b of the fixing screw 20. The metal spacer 22 has a bush portion 23 having a small outer diameter at both ends and inserted into the fixing hole 15, and the bush portion 23 keeps the fixing hole 15 and the screw portion 20 b of the fixing screw 20 from being in direct contact with each other. Can do.

The effect of the fixing structure of the component member which consists of the above structure is demonstrated.
In FIG. 4, the ground land 16 of the first substrate 6 is electrically connected to the protruding portion 18 of the metal housing 2 via the metal washer 21, and the ground land 16 of the second substrate 7 is connected to the metal washer 21 and the fixed portion. The screw 20 is electrically connected to the projecting portion 18 via a head portion 20a and a screw portion 20b. In addition, the ground lands 16 of the first substrate 6 and the second substrate 7 are electrically connected to each other via the metal spacer 22, and are also connected to the metal housing 2 via the mutual ground line 14. In other words, the fixing member 9 fixes the first substrate 6 and the second substrate 7 to the metal casing 2, and connects the ground lands 16 of the ground lines 14 of the first substrate 6 and the second substrate 7 to the metal casing. 2 is electrically connected to ground.

  In the present embodiment, the metal washer 21 and the metal spacer 22 that are conductors have the same shape, and the resin washer 21 ′ and the resin spacer 22 ′ formed of a resin that is an insulator are prepared. 22 can be individually replaced.

  FIG. 5 shows a state in which two metal washers 21 and metal spacers 22 are replaced with resin washers 21 'and resin spacers 22', respectively. Since the ground lands 16 of the first substrate 6 and the second substrate 7 are in contact only with the resin washer 21 ′ or the resin spacer 22 ′, respectively, they are insulated from the metal casing 2, and the ground lands 16 of the first substrate 6 The ground lands 16 of the two substrates 7 are also insulated from each other. That is, the first substrate 6 and the second substrate 7 are fixed while the first substrate 6 and the second substrate 7 are fixed to the metal housing 2 by the fixing member 9 (the fixing screw 20, the washer 21 ′ and the spacer 22 ′). Each ground land 16 of the ground line 14 may be insulated from the metal casing 2 so as not to be grounded.

  Further, as shown in FIG. 6, a resin washer 21 ′ is provided between the second substrate 7 and the head 20a of the fixing screw 20, a resin spacer 22 ′ is provided between the first substrate 6 and the second substrate 7, and If the metal washer 21 is used between the first substrate 6 and the metal casing 2, only the ground land 16 of the first substrate 6 is grounded to the metal casing 2, and the ground land 16 of the second substrate 7 is connected to the metal casing. 2 and the ground land 16 of the first substrate 6 may not be electrically connected.

  Further, as shown in FIG. 7, a metal washer 21 is provided between the second substrate 7 and the head 20a of the screw 20, a resin spacer 22 ′ is provided between the first substrate 6 and the second substrate 7, and the first If a resin washer 21 ′ is used between the substrate 6 and the metal housing 2, contrary to FIG. 6, only the ground land 16 of the second substrate 7 is connected to the metal housing 2 via the metal washer 21 and the fixing screw 20. The ground lands 16 of the first substrate 6 can be made not to be electrically connected to the metal housing 2 and the ground lands 16 of the second substrate 7.

  Further, as shown in FIG. 8, when two metal washers 21 and a resin spacer 22 ′ are used, the ground lands of the first substrate 6 and the second substrate 7 are not electrically connected to each other, but each has a metal housing. The body 2 is electrically connected via a metal washer 21 and a fixing screw 20. In this case, if the front and back ground lines 14 are connected to each other in the vicinity of the ground land 16, the ground strength is almost the same as that in FIG. 4 using the metal spacer 22. If the connection is made at a point away from the land 16, the grounding strength is slightly different from the case of FIG.

  4 to 8, the first substrate 6 and the second substrate 7 are fixed to the metal housing 2, but the same fixing structure is used when the first substrate 6 and the metal base plate 8 are fixed to the metal housing 2. Applies. Further, the first substrate 6 and the second substrate 7 or the metal base plate 8 are fixed to each other using a nut screwed into the fixing screw 20 in place of the protruding portion 18 where the protruding portion 18 of the metal housing 2 is not provided. However, the present invention can also be applied to electrically connecting or insulating the ground lands 16 from each other.

  As described above, according to the present embodiment, when the structural members (the first substrate 6, the second substrate 7, and the metal base plate 8) are fixed to each other or the metal housing 2, the fixing member 9 (particularly, By changing the materials of the washers 21, 21 ′ and the spacers 22, 22 ′), the grounding position of the circuit can be changed (including increase / decrease in the number of grounding points), and the noise characteristics can be changed.

  FIG. 9A shows the frequency distribution of radiation noise of the digital camera 1 when all the fixing members 9 are made of metal. The limit value of class B (for home use) according to VCCI voluntary regulation (200 MHz or less, 40 dB, more than 200 MHz, 47 dB). ). From the figure, it can be seen that there are some frequencies where the radiation noise exceeds the limit value in the high frequency range. That is, the digital camera 1 cannot be sold as a product as it is.

  FIG. 9B shows the frequency distribution of the radiation noise of the digital camera 1 when a part of the metal washer 21 and the metal spacer 22 of the fixing member 9 is replaced with the resin washer 21 ′ and the resin spacer 22 ′. As shown in the figure, in the low frequency range, there is a frequency where the noise is slightly increased, but there is no frequency exceeding the limit value of the VCCI self-regulation. By adopting the combination of the materials of the fixing member 9 at this time in the production, the digital camera 1 was able to reduce the radiation noise and clear the VCCI self-regulation without any design change.

  Further, as shown in FIG. 10, when the ground land 16 of the second substrate 7 is electrically connected (grounded) to the metal housing 2, the second substrate 7 and the head 20 a of the fixing screw 20 are connected. The intermediate metal washer 21 may be omitted. In some cases, the metal washer 21 between the first substrate 6 and the metal housing 2 can be omitted, for example, when all the ground lands 16 of the first substrate 6 are grounded to the metal housing 2.

  FIG. 11 is a modification of the first embodiment. In this example, the bush portion 23 fitted into the fixing hole 15 is provided not on the spacer 22 'but on the washers 21 and 21'. Even when only the first substrate 6 is fixed to the metal housing 2, if the resin washer 21 ′ having the bush portion 23 is used, the screw portion 20 b of the fixing screw 20 does not contact the ground land 16. That is, an arbitrary ground land 16 of the first substrate 6 can be insulated from the metal housing 2, and the ground position of the first substrate 6 can be changed.

  FIG. 12 shows details of the fixing structure of the second embodiment of the present invention. Henceforth, the same code | symbol is attached | subjected to the same component as 1st Embodiment, and description is abbreviate | omitted. The ground lands 16 of the first substrate 6 and the second substrate 7 of this embodiment are provided so as to surround the fixing hole 15 at a distance greater than the height of the thread of the fixing screw 20 from the fixing hole 15. Further, the metal spacer 22 does not have the bush portion 23 as in the first embodiment.

  In this structure, the spacers 22, 22 'are simple cylinders and can be manufactured at low cost. In addition, since the grounding land 16 is separated from the fixing hole 15 without the bush portion 23, even if the screw portion 20 b of the fixing screw 20 abuts against the inner wall of the fixing hole 15, there is no contact with the grounding land 16. The unintended grounding land 16 is not electrically connected to the metal housing 2 via the fixing screw 20. Although not shown, the noise characteristics can be changed by replacing the metal washer 21 and the metal spacer 22 with the resin washer 21 'and the resin spacer 22' having the same shape as in the first embodiment.

  FIG. 13 shows a fixing structure according to a third embodiment of the present invention. The ground land 16 of the present embodiment is further away from the fixing hole 15 and has an inner diameter that is larger than the diameter of the protruding portion 18 of the metal housing 2. In this embodiment, instead of changing the materials of the metal washer 21 and the metal spacer 22, as shown in FIG. 14, the metal small-diameter washer 21 "and the small-diameter whose outer diameter is sufficiently smaller than the inner diameter of the ground land 16 are used. The ground land 16 can also be insulated by replacing the spacer 22 ″.

  Next, FIG. 15 shows a fixing structure according to a fourth embodiment of the present invention. The feature of this embodiment is that the first substrate 6 and the second substrate 7 are provided with the ground line 14 only on the surfaces facing each other. Around the fixing hole 15 of the second substrate 7, relay lands 24 made of a metal layer are provided on both surfaces, and the relay lands 24 on both surfaces are electrically connected to each other through through holes 25. The ground land 16 connected to the ground line 14 or constituting a part of the ground line 14 is formed so as to surround the relay land 24 with a distance.

  FIG. 16 shows the relationship between the relay land 24 and the ground land 16 of the second substrate 7 of FIG. The relay land 24 of the present embodiment has different outer diameters on the front and back sides (the outer diameter of the relay land 24 not surrounded by the ground land 16 is equal to the outer diameter of the ground land 16). It does not have to be circular.

  In the present embodiment, the relay lands 24 of the first substrate 6 and the second substrate 7 are electrically connected to each other via the metal spacer 22 and electrically connected to the metal housing 2 via the metal washer 21 and the fixing screw 20. It is connected to the. Each ground land 16 is electrically connected to the relay land 24 via the metal spacer 22, and is electrically connected to the metal housing 2 via the relay land 24, the metal washer 21 and the fixing screw 20.

  As shown in FIG. 17, when the metal spacer 22 of FIG. 15 is replaced with a small-diameter spacer 22 ″ having a small outer diameter, the ground land 16 of the first substrate 6 is electrically connected to the relay land 24, but the second substrate 7 is not connected to the relay land 24.

  Further, as shown in FIG. 18, the metal spacer 22 of FIG. 15 is replaced with two short spacers of a conductive metal portion 26a in contact with the second substrate 7 and an insulating resin portion 26b in contact with the first substrate 6. By replacing the combined composite spacer 26, only the ground land 16 of the second substrate 7 can be electrically connected to the relay land 24 without electrically connecting the first substrate 6 to the relay land 24. . Thus, only the ground land 16 of the second substrate 7 can be grounded to the metal housing 2.

  Further, as shown in FIG. 19, if the metal spacer 22 of FIG. 15 is replaced with a resin spacer 22 ′, the ground lands 16 of the first substrate 6 and the second substrate 7 are both electrically connected to the relay land 24. It is not connected and is not grounded to the metal housing 2. In the figure, a resin washer 21 ′ is used between the second substrate 7 and the fixing screw 20. However, even if the relay land 24 is grounded to the metal housing 2 using the metal washer 21, the first substrate is used. 6 and the ground land 16 of the second substrate 7 are not grounded to the metal housing 2.

  If the ground land 16 and the relay land 24 of the fourth embodiment are provided so as to surround the fixing hole 15 at a distance as in the fifth embodiment shown in FIG. There is no need to provide the bush portion 23.

  FIG. 21 shows a structure for fixing the first substrate 6, the second substrate 7 and the further third substrate 27 to which the fixing structure of FIG. 20 is applied. The first substrate 6, the second substrate 7, and the third substrate 27 are provided with relay lands 24 and ground lands 16 similar to those of the second substrate 7 of FIG. 17, and are all made of metal spacers 22 in the same direction. 22 ″. The relay land 24 of the first substrate 6 is in direct contact with the metal housing 2 and grounded. The second substrate 7 and the third substrate 27 are metal spacers 22. And connected to the relay land of the first substrate 6 through the small-diameter spacer 22 ″. The ground land 16 of the first substrate 6 is connected to the relay land 24 by a metal spacer 22 having a large outer diameter, but the small land spacer 22 ″ having a small diameter is not in contact with the ground land 16 of the second substrate 7. Therefore, the ground land 24 of the third substrate 27 is connected to the relay land 24 by the metal washer 21, but the metal washer 21 is replaced with a small-diameter washer 21 "having a small outer diameter. And can be insulated from the relay land 24.

  In this way, the relay lands 24 provided on the circuit boards 6, 7, and 27 are electrically connected, and whether each ground land 16 is electrically connected to the relay land 24 is selected. Whether to ground the ground lands 16 of the substrates 6, 7, 27 can be selected.

  In any of the above-described embodiments, it is possible to select whether or not the respective ground lands 16 are electrically connected to each other or to the metal base plate 8 or the metal housing 2 without changing the design. Noise can be reduced. Further, the present invention is effective not only for reducing radiation noise (EMI noise) generated by the device, but also for enhancing the safety (immunity) of the device against electromagnetic waves entering from the outside.

1 is a cross-sectional view of a digital camera having a component fixing structure according to a first embodiment of the present invention. The perspective view which shows the 1st board | substrate and 2nd board | substrate of FIG. The top view which shows the 1st board | substrate and 2nd board | substrate of FIG. The fragmentary sectional view which shows the fixation structure with respect to the metal housing | casing of the 1st board | substrate and 2nd board | substrate of FIG. The fragmentary sectional view which shows the example of selection of the connection member of the fixing structure of FIG. The fragmentary sectional view which shows the example of a different selection of the connection member of the fixing structure of FIG. FIG. 5 is a partial cross-sectional view showing still another example of selection of connection members having a fixed structure in FIG. 4. FIG. 5 is a partial cross-sectional view showing still another example of selection of connection members having a fixed structure in FIG. 4. The graph which shows frequency distribution of the radiation noise of the digital camera of FIG. FIG. 5 is a partial cross-sectional view showing still another example of selection of connection members having a fixed structure in FIG. 4. The fragmentary sectional view which shows the modification of the fixing structure of FIG. The fragmentary sectional view which shows the fixation structure of the structural member of 2nd Embodiment of this invention. The fragmentary sectional view which shows the fixation structure of the structural member of 3rd Embodiment of this invention. FIG. 14 is a partial cross-sectional view illustrating a selection example of a connection member having a fixed structure in FIG. 13. The fragmentary sectional view which shows the fixation structure of the structural member of 4th Embodiment of this invention. The fragmentary perspective view which shows the 2nd board | substrate of FIG. The fragmentary sectional view which shows the example of selection of the connection member of the fixing structure of FIG. The fragmentary sectional view which shows the example of a different selection of the connection member of the fixing structure of FIG. FIG. 16 is a partial cross-sectional view showing still another example of selecting the connection member having the fixed structure shown in FIG. 15. The fragmentary sectional view which shows the fixation structure of the structural member of 5th Embodiment of this invention. The fragmentary sectional view which shows the application example of the fixing structure of FIG.

Explanation of symbols

1 Digital camera 2 Metal enclosure (fixed body)
6 First board 7 Second board 8 Metal base plate 9 Fixing member 14 Ground line 15 Fixing hole 16 Ground land 20 Fixing screw 20a Head 20b Screw part 21 Metal washer 21 'Resin washer 21 "Small diameter washer 22 Metal spacer 22' Resin Spacer 22 ”Small-diameter spacer 23 Bush part 24 Relay land 25 Through hole 26 Divided spacer 27 Third substrate

Claims (16)

Fix the component consisting of the circuit board or metal base plate to the fixed body with the fixing member,
By changing at least one of the material and shape of the fixing member, it is possible to select whether the ground land provided on the component member is electrically connected to or insulated from the fixed body. The fixing structure of the structural member to perform. A plurality of constituent members made of a circuit board or a metal base plate are fixed to each other with a gap or to a fixed body with a fixing member,
The component member is provided with a ground land,
By changing at least one of the material and shape of the fixing member, it is possible to select whether the ground lands are electrically connected or insulated from each other and between the ground lands and the fixed body. A structure for fixing a constituent member, wherein   3. The fixing structure for a constituent member according to claim 1, wherein the constituent member is provided with a plurality of fixing holes for fixing with the fixing member, and a grounding land surrounding the fixing hole. . A fixing structure for fixing two constituent members made of a circuit board or a metal base plate to each other with a gap or both to a fixed body,
The component member is provided with a fixing hole that penetrates the thickness, and a grounding land that surrounds the fixing hole,
A fixing screw penetrating both the fixing holes of the two component members;
A spacer that penetrates through the fixing screw and is sandwiched between the constituent members to define the distance between them;
The two structural members are fixed by a washer that is sandwiched between the structural member and the fixed body, and between the structural member and the head of the fixing screw and penetrates the fixing screw. Fixing structure of component members.   5. The component member according to claim 4, wherein at least one of the spacer and the washer has a bush portion that is fitted into the fixing hole and prevents the fixing screw and the fixing hole from directly contacting each other. Fixed structure.   The said grounding land is provided so that it may surround the said fixing hole at a distance, The fixing structure of the structural member of Claim 4 characterized by the above-mentioned.   The structure for fixing a component member according to any one of claims 4 to 6, wherein the grounding lands are provided on both surfaces of the component member. A fixing structure for fixing a plurality of constituent members made of a circuit board or a metal base plate to each other or a fixed body with a gap therebetween,
Each of the component members is provided with a fixing hole penetrating the thickness,
At least one of the component members is provided such that relay lands electrically connected to each other by through holes on both sides surround the periphery of the fixing hole, and at least one side is provided with a ground land so as to surround the relay lands,
The relay land is electrically connected to each other via a conductive spacer sandwiched between two adjacent component members, and has a fixing screw that passes through the fixing hole, the component member, and the fixed body. Or electrically connected to the fixed body via at least one of a conductive washer sandwiched between the head of the fixing screw and the component member,
The washer or the spacer can be selected to electrically connect or insulate the ground land to the relay land by changing at least one of a shape and a partial material thereof. The fixing structure of the structural member to perform. In a fixing structure for fixing a component made of a circuit board or a metal base plate to a fixed body with a fixing member
By changing at least one of the material and shape of the fixing member, it is possible to select whether to electrically connect or insulate the ground land provided on the component member to the fixed body,
A noise reduction method, wherein a noise characteristic is changed by changing a grounding position by changing a material of the fixing member. In a fixing structure in which a plurality of constituent members made of a circuit board or a metal base plate are fixed to each other with a gap, or to a fixed body with a fixing member,
The component member is provided with a grounding land,
By changing at least one of the material and shape of the fixing member, it is possible to select whether the ground lands are electrically connected or insulated from each other and between the ground lands and the fixed body. age,
A noise reduction method, wherein a noise characteristic is changed by changing at least one of a material and a shape of the fixing member.   The noise reduction method according to claim 9 or 10, wherein the component member is provided with a plurality of fixing holes for fixing with the fixing member, and a grounding land surrounding the fixing hole. In a fixing structure for fixing two constituent members made of a circuit board or a metal base plate to each other with a gap or both to a fixed body,
The component member is provided with a fixing hole that penetrates the thickness, and a grounding land that surrounds the fixing hole,
A fixing screw penetrating both the fixing holes of the two constituent members;
A spacer that penetrates through the fixing screw and is sandwiched between the constituent members to define the distance between them;
The two constituent members are fixed by a washer sandwiched between the constituent member and the fixed body, and the constituent member and a head of the fixing screw, and passed through the fixing screw,
By changing the shape and / or material of at least one of the spacer and the washer, the ground lands of the component members are electrically connected to each other and between the ground lands and the fixed body. A noise reduction method characterized in that noise characteristics are changed by changing the grounding position by selecting whether to insulate.   13. The noise reduction method according to claim 12, wherein at least one of the spacer and the washer has a bush portion that is fitted into the fixing hole and prevents the fixing screw and the fixing hole from directly contacting each other. .   The noise reduction method according to claim 12, wherein the ground land is provided so as to surround the fixing hole at a distance.   The noise reduction method according to claim 12, wherein the ground lands are provided on both surfaces of the component member. In a fixing structure for fixing a plurality of constituent members made of a circuit board or a metal base plate to each other or a fixed body with a gap,
Each of the component members is provided with a fixing hole penetrating the thickness,
At least one component member is provided with relay lands electrically connected to each other by through holes on both sides so as to surround the periphery of the fixing hole, and at least one surface is provided with ground lands so as to surround the relay land,
The relay land is electrically connected to each other via a conductive spacer sandwiched between two adjacent component members, and a fixing screw penetrating the fixing hole, the component member and the fixed body Or electrically connected to the fixed body via at least one of a conductive washer sandwiched between the head of the fixing screw and the component member,
By changing at least one of the shape and partial material of the washer or the spacer, the noise characteristics are changed by selecting whether the ground land is electrically connected to or insulated from the relay land. Noise reduction method.

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