Acceleration Detector

Abstract

Provided is an acceleration detection device that can be reduced in size and that can detect high-frequency acceleration with high precision.　The present invention comprises: a substrate 2 having first and second main surfaces 2a, 2b; an acceleration detection element 3 mounted on the first main surface 2a; first and second circuit components 4, 5 mounted on the substrate 2; a sealing member 10 made of resin and having a first sealing part 11 that covers the acceleration detection element 3 provided on the first main surface 2a, and a second sealing part 12 that covers the second circuit component 5 provided on the second main surface 2b and that includes first and second surfaces 12a, 12b; and high-rigidity members 8 that extend, within the second sealing part 12, in a direction joining the second surface 12b and the second main surface 2b of the substrate 2, and that have a higher rigidity than that of the sealing member 10. In a plan view, the high-rigidity members 8 are positioned further to the outside than the center of gravity of a body section 6 which is constituted by the substrate 2, the acceleration detection element 3, and the first and second circuit components 4, 5.

Description

[Technical field]

[0001] The present invention relates to an acceleration detection device for detecting vibrations or the like of an object. [Background technology]

[0002] Conventionally, various acceleration detection devices equipped with an acceleration detection element have been known. For example, the following Patent Document 1 discloses an acceleration detection device that detects the acceleration of a vehicle. In the acceleration detection device described in Patent Document 1, the acceleration detection element and circuit components are mounted on one side of a substrate. The other side of the substrate is fixed to an object to be detected.

[0003] On the other hand, in the angular velocity detection device described in the following Patent Document 2, the sensor unit is disposed in a housing formed by a wiring board and a lid. The housing is disposed on the circuit board with a space therebetween. The housing is supported on the circuit board by a housing support member made of a low-rigidity material. The space between the housing and the circuit board is connected to the external environment via an orifice or the like. This improves vibration resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-75442 A [Patent Document 2] JP 2011-38908 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the acceleration detection device described in Patent Document 1, the substrate is fixed to a housing that is fixed to the vehicle. Therefore, it is not possible to mount circuit components on the surface of the substrate that faces the housing. This makes it difficult to reduce the size of the acceleration detection device.

[0006] In the angular velocity detector described in Patent Document 2, the part surrounding the space between the housing and the wiring board is easily deformed by vibration and is connected to the external environment. Therefore, it is not possible to mount and seal circuit components in the space. Therefore, it is difficult to miniaturize the angular velocity detector. Furthermore, in this angular velocity detector, the vibration resistance is improved by lowering the resonance frequency, so the performance of detecting high frequencies is reduced.

[0007] An object of the present invention is to provide an acceleration detection device that can be miniaturized and is capable of detecting high-frequency acceleration with high accuracy. [Means for solving the problem]

[0008] The acceleration detection device according to the present invention comprises a substrate including a first main surface and a second main surface opposing each other, an acceleration detection element mounted on the first main surface of the substrate, circuit components mounted on at least the second main surface of the substrate, a first sealing portion covering the acceleration detection element provided on the first main surface of the substrate, and a second sealing portion covering the circuit components provided on the second main surface of the substrate and including a first surface facing the substrate and a second surface facing the first surface, the sealing member being made of resin, and at least one high-rigidity member extending within the second sealing portion in a direction connecting the second surface and the second main surface of the substrate and having a higher rigidity than the sealing member, the high-rigidity member being located outside the center of gravity of a main body formed by the substrate, the acceleration detection element, and the circuit components in a plan view. Effect of the Invention

[0009] According to the present invention, it is possible to provide an acceleration detection device which can be miniaturized and which is capable of detecting high-frequency acceleration with high accuracy. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a schematic perspective view for explaining an acceleration detecting device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic perspective view of the acceleration detecting device according to the first embodiment of the present invention, as viewed from the second main surface side of the substrate. [Diagram 3] FIG. 3 is a schematic cross-sectional view taken along line II in FIG. [Figure 4] FIG. 4 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the first embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic front sectional view of an acceleration detecting device of a first comparative example. [Figure 6] FIG. 6 is a schematic front sectional view of an acceleration detector of a second comparative example. [Figure 7] FIG. 7 is a diagram showing the relationship between frequency and acceleration, for explaining the frequency range in which acceleration can be detected in the first embodiment of the present invention, the first comparative example, and the second comparative example. [Figure 8] FIG. 8 is a schematic plan view for explaining an example of four regions in the first embodiment of the present invention. [Figure 9] FIG. 9 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in a modified example of the first embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the relationship between the total installation area of ​​a plurality of high-rigidity members, the number of high-rigidity members, and the resonance frequency of the entire structure of the acceleration detecting device. [Figure 11] FIG. 11 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the second embodiment of the present invention. [Figure 12] FIG. 12 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the third embodiment of the present invention. [Figure 13] FIG. 13 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the fourth embodiment of the present invention. [Figure 14] FIG. 14 is a schematic front sectional view of an acceleration detecting device according to the fourth embodiment of the present invention. [Figure 15] FIG. 15 is a perspective view of an example of an acceleration detecting element. [Figure 16] FIG. 16 is a perspective view for explaining the internal structure of an example of an acceleration detecting element. [Figure 17] FIG. 17 is a perspective view of an example of an acceleration detecting element. [Figure 18] FIG. 18 is a perspective view for explaining the internal structure of an example of an acceleration detecting element. [Figure 19] FIG. 19 is a schematic perspective view for explaining an acceleration detecting device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be clarified below by describing specific embodiments of the present invention with reference to the drawings.

[0012] It should be noted that each embodiment described in this specification is merely illustrative, and partial substitution or combination of configurations is possible between different embodiments.

[0013] Fig. 1 is a schematic perspective view for explaining an acceleration detecting device according to a first embodiment of the present invention. Fig. 2 is a schematic perspective view of the acceleration detecting device according to the first embodiment as viewed from a second main surface side of a substrate. Fig. 3 is a schematic cross-sectional view along line II in Fig. 1. In Fig. 3, each element is shown by a schematic diagram in which two diagonal lines are added to a rectangle.

[0014] 1 and 2, the acceleration detection device 1 has a substrate 2. In this embodiment, the shape of the substrate 2 is a square in a plan view. However, the shape of the substrate 2 in a plan view is not limited to the above and may be, for example, a rectangle or another polygon. In this specification, a plan view refers to a direction viewed from above in FIG. 3.

[0015] The substrate 2 has a first main surface 2a and a second main surface 2b. The first main surface 2a and the second main surface 2b face each other. The substrate 2 is made of an insulating material such as glass epoxy or alumina. Although not shown, wiring for electrical connection and the like are provided on the first main surface 2a and the second main surface 2b of the substrate 2.

[0016] As shown in Fig. 3, the acceleration detecting device 1 has an acceleration detecting element 3, a plurality of circuit components, and a plurality of high-rigidity members 8. The plurality of circuit components include a plurality of first circuit components 4 and a plurality of second circuit components 5. The acceleration detecting element 3 is mounted on a first main surface 2a of the substrate 2. The acceleration detecting element 3 is an element that detects acceleration applied to the acceleration detecting device 1. The acceleration detecting element 3 outputs an electric signal according to the magnitude of the applied acceleration.

[0017] A plurality of first circuit components 4 are mounted on the first main surface 2a of the substrate 2. A plurality of second circuit components 5 are mounted on the second main surface 2b. The first circuit components 4 and the second circuit components 5 are electrically connected to each other. The first circuit components 4 and the second circuit components 5 constitute an electric circuit for driving the acceleration detection element 3 and outputting a signal from the acceleration detection element 3. It is sufficient that the circuit components are provided on at least the second main surface 2b of the first main surface 2a and the second main surface 2b.

[0018] The substrate 2, the acceleration detection element 3, the plurality of first circuit components 4, and the plurality of second circuit components 5 form a main body 6 of the acceleration detecting device 1. In this embodiment, the acceleration detection element 3 is located at the center of the first main surface 2a of the substrate 2. The center of gravity of the main body 6 is located at the center of the substrate 2. However, the positions of the acceleration detection element 3, the first circuit components 4, and the second circuit components 5 are not particularly limited. The position of the center of gravity of the main body 6 is also not limited to the above.

[0019] The acceleration detecting device 1 has a sealing member 10. The sealing member 10 is made of resin. The sealing member 10 has a first sealing portion 11 and a second sealing portion 12. The first sealing portion 11 is provided on the first main surface 2a of the substrate 2. The first sealing portion 11 covers the acceleration detecting element 3 and the multiple first circuit components 4. The second sealing portion 12 is provided on the second main surface 2b. The second sealing portion 12 covers the multiple second circuit components 5. The sealing member 10 seals the acceleration detecting element 3, the multiple first circuit components 4, and the multiple second circuit components 5 in the acceleration detecting device 1.

[0020] The second sealing portion 12 has a first surface 12a and a second surface 12b. The first surface 12a and the second surface 12b face each other. The first surface 12a faces the second main surface 2b of the substrate 2. On the other hand, the second surface 12b is a surface located outside the acceleration detecting device 1. As shown in FIG. 3, the second surface 12b is fixed to a detection target 13 of the acceleration detecting device 1. The second surface 12b is a mounting surface of the acceleration detecting device 1.

[0021] The resin material of the sealing member 10 may be, for example, a thermosetting resin such as an epoxy resin, a silicone resin, or a polyurethane resin, or a thermoplastic resin such as an acrylic resin or a polyethylene resin.

[0022] A plurality of high-rigidity members 8 are provided in the second sealing portion 12 of the sealing member 10. The plurality of high-rigidity members 8 extend in a direction connecting the second surface 12b of the second sealing portion 12 and the second main surface 2b of the substrate 2. The high-rigidity members 8 are made of a material having higher rigidity than the sealing member 10. In this embodiment, the high-rigidity members 8 are made of cylindrical metal pins. Note that the high-rigidity members 8 are not limited to being cylindrical, and may be columnar bodies of any shape. As the metal material of the high-rigidity members 8, for example, at least one metal selected from the group consisting of iron, aluminum, nickel, and alloys mainly made of these metals can be used. However, as the material of the high-rigidity members 8, appropriate ceramics can also be used. It is sufficient that at least one high-rigidity member 8 is provided.

[0023] Fig. 4 is a schematic plan view showing the positional relationship between the substrate and the high-rigidity member in the first embodiment. In Fig. 4, only the substrate 2 and the high-rigidity member 8 are omitted. The same is true for the other schematic plan views.

[0024] In this embodiment, eight high-rigidity members 8 are provided. The multiple high-rigidity members 8 are located outside the center of gravity O of the main body 6 in a planar view. More specifically, the multiple high-rigidity members 8 surround the center of gravity O in a planar view.

[0025] Returning to FIG. 3, one end of each of the multiple high-rigidity members 8 is bonded to the second main surface 2b of the substrate 2 by a conductive bonding material 9a. The multiple high-rigidity members 8 are electrically connected to the wiring provided on the substrate 2, the acceleration detection element 3, the multiple first circuit components 4, and the multiple second circuit components 5 via the conductive bonding material 9a. Note that the multiple high-rigidity members 8 do not necessarily have to be electrically connected to the acceleration detection element 3, the multiple first circuit components 4, and the multiple second circuit components 5. The conductive bonding material 9a can be an appropriate conductive bonding material such as solder or a conductive adhesive. Note that an insulating bonding material may be used instead of the conductive bonding material 9a.

[0026] In this embodiment, of both ends of the multiple high-rigidity members 8, the end farther from the substrate 2 is bonded to the attachment surface 13a of the detection object 13 via a bonding material 9b. This fixes the acceleration detection device 1 to the detection object 13. The bonding material 9b may be a conductive bonding material or a non-conductive bonding material.

[0027] A first feature of the acceleration detecting device 1 is that the acceleration detecting element 3 is mounted on the first main surface 2a of the substrate 2, and the second circuit component 5 is mounted on the second main surface 2b of the substrate 2. This makes it possible to reduce the area of ​​the substrate 2 for providing the circuit components, thereby making it possible to miniaturize the acceleration detecting device 1. Note that, as in this embodiment, it is preferable that the circuit components are provided on both the first main surface 2a and the second main surface 2b of the substrate 2. This makes it possible to make the acceleration detecting device 1 even more compact.

[0028] A second feature of the acceleration detecting device 1 is that the high-rigidity member 8 is located outside the center of gravity O of the main body 6 constituted by the substrate 2, the acceleration detecting element 3, the first circuit component 4, and the second circuit component 5 in a plan view. This makes it possible to suppress vibrations in the acceleration detecting device 1 and to detect high-frequency acceleration with high accuracy. This will be described below with reference to the present embodiment as well as a first comparative example and a second comparative example.

[0029] The first comparative example shown in Fig. 5 differs from the first embodiment in that it does not have a high-rigidity member 8. The second comparative example shown in Fig. 6 differs from the first embodiment in that it has one high-rigidity member 8, and that the high-rigidity member 8 overlaps with the center of gravity of the main body portion 6 in a plan view.

[0030] FIG. 7 is a diagram showing the relationship between frequency and acceleration, for explaining the frequency range in which acceleration can be detected in the first embodiment, the first comparative example, and the second comparative example.

[0031] As shown in FIG. 7, in the first embodiment, at frequencies lower than the frequency shown by the two-dot chain line D, the acceleration applied to the element is almost independent of the frequency. On the other hand, at frequencies higher than the frequency shown by the two-dot chain line D, the acceleration is dependent on the frequency. Therefore, at frequencies higher than the frequency shown by the two-dot chain line D, the detected acceleration is affected by the frequency, and the detection accuracy is low. Therefore, in the first embodiment, the acceleration can be detected with high accuracy in a frequency range lower than the frequency shown by the two-dot chain line D. Similarly, in the first comparative example, the acceleration can be suitably detected in a frequency range lower than the frequency shown by the two-dot chain line E. In the second comparative example, the acceleration can be suitably detected in a frequency range lower than the frequency shown by the two-dot chain line F. And the frequency shown by the two-dot chain line D is higher than the frequencies shown by the two-dot chain line E and the two-dot chain line F. Therefore, in the first embodiment, it can be seen that the acceleration can be detected with high accuracy at frequencies higher than those of the first comparative example and the second comparative example. The reason for this will be explained below.

[0032] In the first comparative example, the acceleration applied to the element is at a maximum value at a frequency higher than the two-dot chain line E. This is because the entire structure of the acceleration detection device resonates. The frequency at which the acceleration is at a maximum value in FIG. 7 is a schematic representation of the resonance frequency of the entire structure of the acceleration detection device when the acceleration detection device is fixed to the detection object 13. As shown in FIG. 5, in the first comparative example, the acceleration detection device is fixed to the detection object 13 by the sealing member 10. The sealing member 10 is made of resin and has low rigidity. Furthermore, as shown by the arrow B, the entire structure of the acceleration detection device easily vibrates in a direction approximately parallel to the first main surface 2a and the second main surface 2b of the substrate 2. Therefore, in the first comparative example, the resonance frequency of the entire structure of the acceleration detection device is low.

[0033] As shown in Fig. 6, in the second comparative example, a high-rigidity member 8 is provided. Therefore, the resonant frequency of the entire structure of the acceleration detecting device is high. However, as shown by the arrow C, the vibration in the direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2 is not sufficiently suppressed. Therefore, although the resonant frequency of the entire structure of the acceleration detecting device in the second comparative example is higher than that of the first comparative example, it is not sufficiently high.

[0034] In contrast, in the acceleration detecting device 1 of the first embodiment shown in Fig. 3, the multiple high-rigidity members 8 are located outward from the center of gravity of the main body 6 in a plan view. This allows the entire acceleration detecting device 1 to be suitably supported by the high-rigidity members 8. This makes it possible to suppress vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2. In addition, the rigidity of the high-rigidity members 8 is higher than the rigidity of the sealing member 10. This makes it possible to effectively increase the resonant frequency of the entire structure of the acceleration detecting device 1, and to detect high-frequency acceleration with high accuracy.

[0035] A preferred configuration for the first embodiment will be described below.

[0036] As shown in Fig. 4, the multiple high-rigidity members 8 are preferably located on the outer periphery side of the substrate 2. More specifically, the multiple high-rigidity members 8 are located outside the area indicated by the two-dot chain line A in Fig. 4. When the distance between the center of gravity O of the main body portion 6 and the outer periphery of the substrate 2 is L, the two-dot chain line A is a line connecting points at a distance of 1 / 2 of the distance L.

[0037] More specifically, the outer periphery of the substrate 2 includes a plurality of facing portions 2c. The facing portions 2c are located on a straight line connecting the center of gravity O and the high-rigidity member 8, sandwich the high-rigidity member 8 together with the center of gravity O, and face the center of gravity O. In the first embodiment, eight high-rigidity members 8 are provided, and therefore the substrate 2 has eight facing portions 2c. As in the first embodiment, the distance between the center of gravity O and the center of the high-rigidity member 8 in a plan view is preferably 1 / 2 or more times the distance L between the center of gravity O of the main body 6 and the facing portions 2c. This allows the entire acceleration detector 1 to be effectively supported by the high-rigidity member 8. This allows the vibration in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2 to be effectively suppressed. Therefore, it is possible to detect high-frequency acceleration with even higher accuracy.

[0038] Fig. 8 is a schematic plan view for explaining an example of four regions in the first embodiment. Note that the straight lines G and H in Fig. 8 are just examples, and the directions of the straight lines G and H are arbitrary. It is sufficient that the straight lines G and H are perpendicular to each other. On the other hand, the dashed line K in Fig. 8 is a line connecting the centers of the multiple high-rigidity members 8.

[0039] As shown in FIG. 8, in a plan view, four regions bounded by two straight lines G and H that pass through the center of gravity O of the main body 6 and are perpendicular to each other are defined as a first region J1, a second region J2, a third region J3, and a fourth region J4. The first region J1 is adjacent to the second region J2 and the fourth region J4, but is not adjacent to the third region J3. In the first embodiment, high-rigidity members 8 are located in both the first region J1 and the third region J3. In this way, it is preferable that the multiple high-rigidity members 8 include at least one pair of high-rigidity members 8 located in two non-adjacent regions among the four regions. In this case, the entire acceleration detection device 1 can be supported by at least one pair of high-rigidity members 8 in regions facing each other across the center of gravity O. This makes it possible to effectively suppress vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2.

[0040] It is more preferable that at least one pair of high-rigidity members 8 located in the first region J1 and the third region J3, respectively, face each other across the center of gravity O of the main body 6. This makes it possible to more effectively suppress vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2.

[0041] As in the first embodiment, it is more preferable that at least one high-rigidity member 8 is located in each of the first region J1, the second region J2, the third region J3, and the fourth region J4. In this case, the entire acceleration detecting device 1 can be supported by at least one pair of high-rigidity members 8 in each of two sets of regions facing each other with the center of gravity O of the main body 6 in between. This makes it possible to further suppress vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2.

[0042] In this case, it is preferable that at least one pair of high-rigidity members 8 located in the first region J1 and the third region J3, respectively, face each other with the center of gravity O of the main body 6 in between. In addition, it is more preferable that at least one pair of high-rigidity members 8 located in the second region J2 and the fourth region J4, respectively, face each other with the center of gravity O in between. This makes it possible to more effectively suppress vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2. Therefore, it is possible to detect high-frequency acceleration with even higher accuracy.

[0043] As described above, the straight lines G and H only need to be perpendicular to each other, and the directions of the straight lines G and H are arbitrary. The positions of the above four regions are determined by the straight lines G and H in any direction. It is preferable that the positions of the above four regions bounded by any of the straight lines G and H in any direction and the positions of the multiple high-rigidity members 8 have any of the above relationships. Note that the above four regions are established even when the shape of the substrate 2 in a plan view is other than a square. Therefore, regardless of the shape of the substrate 2 in a plan view, it is preferable that the positions of the four regions and the positions of the multiple high-rigidity members 8 have any of the above relationships.

[0044] As shown by the dashed line K in FIG. 8, the shape of the portion surrounded by the lines connecting the centers of the multiple high-rigidity members 8 is a square. More specifically, the shape of the portion surrounded by the lines connecting the centers of the multiple high-rigidity members 8, which has the largest area, is a square. The shape of the substrate 2 in plan view is also a square. In this way, it is preferable that the shape of the portion surrounded by the lines connecting the centers of the multiple high-rigidity members 8, which has the largest area, and the shape of the substrate 2 have a similar relationship. In this case, it is easy to support the entire acceleration detection device 1 uniformly. It is more preferable that, in plan view, one high-rigidity member 8 is located on each of the lines connecting the center of the substrate 2 and each vertex of the substrate 2. In this case, the entire acceleration detection device 1 can be supported more reliably and uniformly. Thereby, the resonance frequency of the entire structure of the acceleration detection device 1 can be increased more reliably and effectively, and high-frequency acceleration can be detected with even higher accuracy.

[0045] Similarly, even if the shape of the substrate in plan view is a polygon other than a square, such as a rectangle, it is preferable that the shape of the portion surrounded by lines connecting the centers of the multiple high-rigidity members in plan view has a maximum area, and that the shape of the portion surrounded by the lines connecting the centers of the multiple high-rigidity members has a similar relationship to the shape of the substrate. In this case as well, high-frequency acceleration can be detected with even greater accuracy.

[0046] FIG. 9 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in a modified example of the first embodiment.

[0047] In this modification, four high-rigidity members 8 are provided. More specifically, in a plan view, each high-rigidity member 8 is located on a diagonal line on the second main surface 2b of the substrate 2. In this modification, two pairs of high-rigidity members 8 face each other with the center of gravity O of the main body 6 in between. Therefore, vibrations in a direction substantially parallel to the first main surface 2a and the second main surface 2b of the substrate 2 can be effectively suppressed, and high-frequency acceleration can be detected with high accuracy. Although not shown, the first circuit component and the second circuit component are arranged in the same manner as in the first embodiment. This allows the acceleration detection device to be miniaturized.

[0048] Incidentally, it is preferable to increase the number of high-rigidity members 8 rather than increasing the area of ​​each high-rigidity member 8 in a plan view. This makes it possible to effectively increase the resonance frequency of the entire structure of the acceleration detecting device. This will be described below.

[0049] As in the modified example of the first embodiment, in a case where four high-rigidity members 8 were provided, the resonant frequency was measured each time the area of ​​each high-rigidity member 8 was changed. More specifically, the diameter of the high-rigidity member 8 in plan view was changed in increments of 0.2 mmφ from 0.6 mmφ to 1.2 mmφ. Meanwhile, the resonant frequency was measured each time the number of high-rigidity members 8 was changed without changing the area of ​​each high-rigidity member 8. More specifically, the number of high-rigidity members 8 was changed in increments of 1 from 4 to 8.

[0050] 10 is a diagram showing the relationship between the total installation area of ​​multiple high-rigidity members, the number of high-rigidity members, and the resonance frequency of the entire structure of the acceleration detecting device. The total installation area of ​​multiple high-rigidity members 8 is the same as the sum of the areas of the multiple high-rigidity members 8 in a plan view.

[0051] As shown in Fig. 10, it can be seen that the larger the total installation area of ​​the multiple high-rigidity members 8, the higher the resonant frequency of the entire structure of the acceleration detection device. It can also be seen that when the number of high-rigidity members 8 is increased, the slope of the change in resonant frequency with respect to the change in area is greater than when the area of ​​each high-rigidity member 8 is increased. Furthermore, for example, when the total installation area of ​​the high-rigidity members 8 is about 2 mm 2 It can be seen that when seven high-rigidity members 8 are provided, the resonance frequency is higher than when four high-rigidity members 8 are provided. Therefore, it is preferable to increase the number of high-rigidity members 8 rather than increasing the area of ​​each high-rigidity member 8. This makes it possible to effectively increase the resonance frequency of the entire structure of the acceleration detection device.

[0052] This is because by reducing the area of ​​each high-rigidity member 8, it becomes easier to arrange the high-rigidity members 8 near the outer periphery of the substrate 2. More specifically, as acceleration detection devices become more compact, high accuracy is required in arranging the high-rigidity members 8 in the manufacturing process. By reducing the area of ​​each high-rigidity member 8, it is possible to realize an acceleration detection device in which the high-rigidity members 8 are located near the outer periphery of the substrate 2. In addition, by increasing the number of high-rigidity members 8, it is possible to increase the number of pairs of high-rigidity members 8 provided in non-adjacent regions out of the four regions shown in FIG. 8. This makes it possible to effectively increase the resonance frequency.

[0053] The first sealing portion 11 and the second sealing portion 12 in the sealing member 10 shown in FIG. 3 are preferably made of the same resin. This makes it easier to manufacture. However, the first sealing portion 11 and the second sealing portion 12 may be made of different resins. The first sealing portion 11 and the second sealing portion 12 may be connected to each other via the side surface of the substrate 2 and integrated together. In other words, the substrate 2 may be embedded in the sealing member 10.

[0054] In the first embodiment, of both ends of the high-rigidity member 8, the end farther from the substrate 2 is exposed to the outside of the sealing member 10. This end of the high-rigidity member 8 is located more inward in the second sealing portion 12 than the second surface 12b of the second sealing portion 12. In this manner, a step is provided between the second surface 12b and the end of the high-rigidity member 8. However, a step does not necessarily have to be provided between the second surface 12b and the end of the high-rigidity member 8.

[0055] 3, in the first embodiment, the second sealing portion 12 of the sealing member 10 is not in contact with the detection object 13. However, when the acceleration detecting device 1 is joined to the detection object 13, the second sealing portion 12 may be in contact with the detection object 13.

[0056] However, the detection object 13 is not particularly limited. For example, the acceleration detection device of the present invention can be mounted on various detection objects such as machine tools and vehicles. The acceleration detection device 1 may be fixed to the detection object 13 via an intermediate substrate made of an insulating material such as glass epoxy or alumina.

[0057] FIG. 11 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the second embodiment.

[0058] This embodiment differs from the first embodiment in that each high-rigidity member 28 has a rectangular prism shape and that, in a plan view, part of the outer periphery of each high-rigidity member 28 overlaps with the outer periphery of the substrate 2. In all other respects, the acceleration detecting device of this embodiment has the same configuration as the acceleration detecting device 1 of the first embodiment.

[0059] The multiple high-rigidity members 28 are located outboard of the center of gravity O of the main body 6 in plan view. Furthermore, a portion of the outer periphery of each high-rigidity member 28 overlaps with the outer periphery of the substrate 2 in plan view. This allows the entire structure of the acceleration detecting device to be effectively supported by the high-rigidity members 28. Furthermore, although not shown, the first circuit component and the second circuit component are arranged in the same manner as in the first embodiment. This allows the acceleration detecting device to be miniaturized and allows high-frequency acceleration to be detected with even greater accuracy.

[0060] In addition, the outer periphery of the high-rigidity member 28 does not have to overlap with the outer periphery of the substrate 2 in plan view.

[0061] As shown in Fig. 11, the shape of the high-rigidity member 28 in a plan view is a square. However, the shape of the high-rigidity member 28 in a plan view may also be a rectangle. In these cases, the high-rigidity member 28 has linear portions in a plan view. This makes it possible to more reliably arrange the high-rigidity member 28 near the outer periphery of the substrate 2 even when the acceleration detection device is small. Therefore, the resonant frequency of the entire structure of the acceleration detection device can be more reliably and effectively increased, and high-frequency acceleration can be detected with even greater accuracy.

[0062] FIG. 12 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the third embodiment.

[0063] This embodiment differs from the first embodiment in that the shape of the high-rigidity member 38 is frame-shaped, that there is one high-rigidity member 38, and that, in a plan view, the entire outer periphery of the high-rigidity member 38 overlaps with the outer periphery of the substrate 2. Other than the above points, the acceleration detecting device of this embodiment has the same configuration as the acceleration detecting device 1 of the first embodiment.

[0064] The high-rigidity member 38 is located outboard of the center of gravity O of the main body 6 in plan view. In plan view, the outer periphery of the high-rigidity member 38 overlaps with the outer periphery of the substrate 2. This allows the entire structure of the acceleration detecting device to be effectively supported by the high-rigidity member 38. Furthermore, although not shown, the first circuit components and the second circuit components are arranged in the same manner as in the first embodiment. This allows the acceleration detecting device to be miniaturized, and allows high-frequency acceleration to be detected with even greater accuracy.

[0065] As in this embodiment, it is preferable that the external shape of the high-rigidity member 38 and the shape of the substrate 2 are congruent in plan view. In this case, it is easy to uniformly support the entire acceleration detecting device. This effectively increases the resonance frequency of the entire structure of the acceleration detecting device, and enables detection of high-frequency acceleration with even higher accuracy.

[0066] In addition, in a plan view, the outer peripheral edge of high-rigidity member 38 does not have to overlap with the outer peripheral edge of substrate 2. In a plan view, the outer peripheral edge of high-rigidity member 38 may be located inside the outer peripheral edge of substrate 2. However, in a plan view, it is preferable that at least a part of the outer peripheral edge of high-rigidity member 38 overlaps with the outer peripheral edge of substrate 2. Alternatively, in a plan view, it is preferable that the outer shape of high-rigidity member 38 and the shape of substrate 2 have a similar relationship. Even in these cases, the resonance frequency of the entire structure of the acceleration detection device can be increased.

[0067] Even if the shape of the substrate in plan view is a polygon other than a square, such as a rectangle, it is preferable that the outer shape of the high-rigidity member and the shape of the substrate have a congruent or similar relationship in plan view. In this case too, high-frequency acceleration can be detected with even greater accuracy.

[0068] A fourth embodiment will be described below. In the fourth embodiment, the high-rigidity member corresponding to the high-rigidity member in the first to third embodiments and the modified examples is a first high-rigidity member.

[0069] Fig. 13 is a schematic plan view showing the positional relationship between a substrate and a high-rigidity member in the fourth embodiment, and Fig. 14 is a schematic front sectional view of the acceleration detector according to the fourth embodiment.

[0070] 13, the present embodiment differs from the third embodiment in that it has a second high-rigidity member 48B in addition to a first high-rigidity member 48A. Except for the above, the acceleration detecting device of the present embodiment has the same configuration as the acceleration detecting device of the third embodiment.

[0071] The first high-rigidity member 48A is provided in the same manner as the high-rigidity member 38 serving as the first high-rigidity member in the third embodiment. Furthermore, as shown in Fig. 14, the first circuit component 4 and the second circuit component 5 are arranged in the same manner as in the first embodiment. Therefore, the acceleration detection device can be made smaller, and high-frequency acceleration can be detected with even higher accuracy.

[0072] The second high-rigidity member 48B is provided in the same manner as the high-rigidity member 8 as the first high-rigidity member in the first embodiment, except for its position in plan view. More specifically, the second high-rigidity member 48B is provided in a region overlapping the acceleration detection element 3 in plan view. The second high-rigidity member 48B extends in a direction connecting the second surface 12b of the second sealing portion 12 in the sealing member 10 and the second main surface 2b of the substrate 2. The second high-rigidity member 48B is made of a material having higher rigidity than the sealing member 10. In this embodiment, the second high-rigidity member 48B is made of a cylindrical metal pin. Note that the second high-rigidity member 48B is not limited to a cylindrical shape, and may be a columnar body of any shape. The second high-rigidity member 48B may be made of the same material as the first high-rigidity member 48A.

[0073] One end of the second high-rigidity member 48B is bonded to the second main surface 2b of the substrate 2 by a conductive bonding material 9a. The second high-rigidity member 48B is electrically connected to the wiring provided on the substrate 2, the acceleration detection element 3, the plurality of first circuit components 4, and the plurality of second circuit components 5 via the conductive bonding material 9a. Note that the second high-rigidity member 48B does not necessarily have to be electrically connected to the acceleration detection element 3, the plurality of first circuit components 4, and the plurality of second circuit components 5. The conductive bonding material 9a can be an appropriate conductive bonding material such as solder or a conductive adhesive. Note that an insulating bonding material can be used instead of the conductive bonding material 9a.

[0074] In this embodiment, of both ends of the second high-rigidity member 48B, the end farther from the substrate 2 is bonded via a bonding material 9b to the attachment surface 13a of the detection object 13. The bonding material 9b may be a conductive bonding material or a non-conductive bonding material.

[0075] By providing the second high-rigidity member 48B as described above, it is possible to detect acceleration of even higher frequencies. At least one second high-rigidity member 48B may be provided in a region overlapping with the acceleration detecting element 3 in a plan view. That is, although one second high-rigidity member 48B is provided in this embodiment, multiple second high-rigidity members 48B may be provided.

[0076] The acceleration detection element 3 is an appropriate acceleration detection element that outputs an electric signal according to the magnitude of the applied acceleration. Therefore, as long as it performs such a function, the structure of the acceleration detection element 3 is not particularly limited, but an example will be described with reference to Figs. 15 and 16.

[0077] Fig. 15 is a perspective view of an example of an acceleration detection element, and Fig. 16 is a perspective view for explaining the internal structure of the example of the acceleration detection element.

[0078] As shown in FIG. 15, the acceleration detection element 3 has an element substrate 51 and a cap 52. The cap 52 is fixed to the element substrate 51. As shown in FIG. 16, the acceleration detection element 3 has a piezoelectric element 53 for detecting acceleration. The piezoelectric element 53 is sealed in a container formed by the cap 52 and the element substrate 51. The piezoelectric element 53 is mounted on the element substrate 51. The piezoelectric element 53 has a strip-shaped, elongated piezoelectric body 53a. Electrodes 53b and 53c are provided on both sides of the piezoelectric body 53a. The piezoelectric element 53 is a cantilever beam and is attached to the element substrate 51. When acceleration is applied to the piezoelectric element 53, the piezoelectric element 53 vibrates, and an electric signal is output due to the piezoelectric effect.

[0079] Another example of the acceleration detecting element will be described with reference to FIGS.

[0080] Fig. 17 is a perspective view of an example of an acceleration detection element, and Fig. 18 is a perspective view for explaining the internal structure of the example of the acceleration detection element.

[0081] As shown in FIG. 17, the acceleration detection element has a first clamping member 65, a second clamping member 66, a first exterior substrate 67, and a second exterior substrate 68. As shown in FIG. 18, the acceleration detection element has a piezoelectric element 64. The piezoelectric element 64 is rectangular. The piezoelectric element 64 has a first piezoelectric layer, a second piezoelectric layer, and a detection electrode, which are not shown. The first piezoelectric layer and the second piezoelectric layer are made of lead zirconate titanate ceramics. However, the materials of the first piezoelectric layer and the second piezoelectric layer are not limited to the above. The detection electrodes are provided on the outer surface of the first piezoelectric layer and the outer surface of the second piezoelectric layer, respectively.

[0082] A first clamping member 65 and a second clamping member 66 are joined to the piezoelectric element 64. The piezoelectric element 64 is a cantilever beam and is supported by the first clamping member 65 and the second clamping member 66. The first clamping member 65 and the second clamping member 66 each have a groove that opens towards the piezoelectric element 64. The groove forms a space that does not impede the displacement of the piezoelectric element 64 due to acceleration.

[0083] The first exterior substrate 67 and the second exterior substrate 68 are made of an insulating material. The first exterior substrate 67 is a flat plate-shaped member. The second exterior substrate 68 has a recess. The recess forms a space that does not hinder the displacement of the piezoelectric element 64 due to acceleration. The piezoelectric element 64, the first clamping member 65, and the second clamping member 66 are disposed between the first exterior substrate 67 and the second exterior substrate 68.

[0084] The acceleration detection element may be an acceleration detection element including a capacitance element instead of a piezoelectric element.

[0085] In the above, an example of the manner in which the acceleration detection element 3 is mounted on the substrate 2 is shown with reference to Fig. 1 etc. However, the manner in which the acceleration detection element 3 is mounted on the substrate 2 is not particularly limited. Fig. 19 shows an example in which the acceleration detection element shown in Figs. 17 and 18 is mounted on the substrate in a manner different from that shown in Fig. 1 etc.

[0086] FIG. 19 is a schematic perspective view for explaining an acceleration detecting device according to a fifth embodiment of the present invention.

[0087] The acceleration detection element 63 is the acceleration detection element shown in Figures 17 and 18. The acceleration detection element 63 is mounted near the outer periphery of the first main surface 2a of the substrate 2. In this manner, the acceleration detection element 63 may be mounted in a portion other than the center of the substrate 2. In addition to the acceleration detection element 63, a plurality of first circuit components 4 are also mounted on the first main surface 2a.

[0088] The acceleration detection element 63 is mounted on the first main surface 2a of the substrate 2 so that the first clamping member 65, the first exterior substrate 67, and the second exterior substrate 68 shown in Fig. 17 are in contact with the first main surface 2a of the substrate 2. Therefore, the detection axis of the acceleration detection element 63 is perpendicular to the second surface 12b of the second sealing portion 12. In other words, the detection axis is perpendicular to the mounting surface of the acceleration detection device 61. For example, when the acceleration detection device 61 is mounted on a horizontal surface, the detection axis of the acceleration detection element 63 is in the vertical direction.

[0089] In this embodiment, a plurality of second circuit components 5 are mounted on the second main surface 2b of the substrate 2, similarly to the first embodiment shown in Fig. 2. Then, as described above, the acceleration detecting element 63 is mounted on the first main surface 2a. This makes it possible to reduce the area of ​​the portion of the substrate 2 for providing the circuit components, and thus makes it possible to miniaturize the acceleration detecting device 61.

[0090] In this embodiment, the main body is made up of the substrate 2, the acceleration detection element 63, the plurality of first circuit components 4, and the plurality of second circuit components. The acceleration detection element 63, the plurality of first circuit components 4, and the plurality of second circuit components are mounted on the substrate 2 such that the high rigidity member 8 is located outward from the center of gravity of the main body in a plan view. This makes it possible to suppress vibrations in the acceleration detection device 61, as in the first embodiment, and to detect high frequency acceleration with high accuracy. [Explanation of symbols]

[0091] 1...Acceleration detection device 2...Substrate 2a, 2b...First and second principal surfaces 2c…Facing part 3...Acceleration detection element 4,5...First and second circuit components 6…Main body 8...High rigidity material 9a...Conductive bonding material 9b...Joining material 10...Sealing member 11, 12...First and second sealing portions 12a, 12b...First and second faces 13...Detection target 13a…Mounting surface 28, 38…High rigidity members 48A, 48B: First and second high-rigidity members 51...element substrate 52…Cap 53...Piezoelectric element 53a...Piezoelectric body 53b,53c...electrode 61...Acceleration detection device 63...Acceleration detection element 64...Piezoelectric element 65, 66...First and second clamping members 67, 68…First and second exterior substrates J1~J4: 1st to 4th regions O…center of gravity

Claims

1. a substrate including a first major surface and a second major surface opposed to each other; an acceleration detection element mounted on the first main surface of the substrate; a circuit component mounted on at least the second main surface of the first main surface and the second main surface of the substrate; a sealing member made of resin, the sealing member having a first sealing portion covering the acceleration detection element provided on the first main surface of the substrate, and a second sealing portion covering the circuit components provided on the second main surface of the substrate and including a first surface facing the substrate and a second surface opposite to the first surface; a plurality of high-rigidity members extending in a direction connecting the second surface and the second main surface of the substrate within the second sealing portion and having a higher rigidity than the sealing member; Equipped with the high-rigidity member is located outside a center of gravity of a main body portion constituted by the substrate, the acceleration detection element, and the circuit components in a plan view, When viewed in a plan view, four regions defined as first to fourth regions are defined as regions that pass through the center of gravity of the main body and are bounded by two straight lines that are perpendicular to each other, the plurality of high-rigidity members include at least one pair of the high-rigidity members that are located in two of the first to fourth regions that are not adjacent to each other, At least one pair of the high-rigidity members are opposed to each other across the center of gravity of the main body.

2. a substrate including a first major surface and a second major surface opposed to each other; an acceleration detection element mounted on the first main surface of the substrate; a circuit component mounted on at least the second main surface of the first main surface and the second main surface of the substrate; a sealing member made of resin, the sealing member having a first sealing portion covering the acceleration detection element provided on the first main surface of the substrate, and a second sealing portion covering the circuit components provided on the second main surface of the substrate and including a first surface facing the substrate and a second surface opposite to the first surface; at least one high-rigidity member extending in a direction connecting the second surface and the second main surface of the substrate in the second sealing portion and having a rigidity higher than that of the sealing member; Equipped with the high-rigidity member is located outside a center of gravity of a main body portion constituted by the substrate, the acceleration detection element, and the circuit components in a plan view, The high rigidity member has a rectangular prism shape.

3. a substrate including a first major surface and a second major surface opposed to each other; an acceleration detection element mounted on the first main surface of the substrate; a circuit component mounted on at least the second main surface of the first main surface and the second main surface of the substrate; a sealing member made of resin, the sealing member having a first sealing portion covering the acceleration detection element provided on the first main surface of the substrate, and a second sealing portion covering the circuit components provided on the second main surface of the substrate and including a first surface facing the substrate and a second surface opposite to the first surface; at least one high-rigidity member extending in a direction connecting the second surface and the second main surface of the substrate in the second sealing portion and having a rigidity higher than that of the sealing member; Equipped with the high-rigidity member is located outside a center of gravity of a main body portion constituted by the substrate, the acceleration detection element, and the circuit components in a plan view, The high rigidity member of the acceleration detection device has a frame-like shape.

4. a substrate including a first major surface and a second major surface opposed to each other; an acceleration detection element mounted on the first main surface of the substrate; a circuit component mounted on at least the second main surface of the first main surface and the second main surface of the substrate; a sealing member made of resin, the sealing member having a first sealing portion covering the acceleration detection element provided on the first main surface of the substrate, and a second sealing portion covering the circuit components provided on the second main surface of the substrate and including a first surface facing the substrate and a second surface opposite to the first surface; at least one high-rigidity member extending in a direction connecting the second surface and the second main surface of the substrate in the second sealing portion and having a rigidity higher than that of the sealing member; Equipped with the high-rigidity member is located outside a center of gravity of a main body portion constituted by the substrate, the acceleration detection element, and the circuit components in a plan view, the high-rigidity member is a first high-rigidity member, the acceleration detection device further comprising at least one second high-rigidity member provided in a region overlapping with the acceleration detection element in a planar view and extending in a direction connecting the second surface and the second main surface of the substrate within the second sealing portion of the sealing member.

5. 5. The acceleration detection device according to claim 1, wherein when a portion of the outer peripheral edge of the substrate is located on a straight line connecting the center of gravity of the main body portion and the high rigidity member, sandwiches the high rigidity member together with the center of gravity of the main body portion, and faces the center of gravity of the main body portion, the distance between the center of gravity of the main body portion and the center of the high rigidity member in a planar view is at least half the distance between the center of gravity of the main body portion and the facing portion.

6. The substrate has a polygonal shape in a plan view; 2. The acceleration detection device according to claim 1, wherein, in a plan view, an area of ​​a portion surrounded by a line connecting the centers of the plurality of high-rigidity members is maximized, and a shape of the surrounded portion and a shape of the substrate are similar to each other.

7. 2. The acceleration detection device according to claim 1, wherein the highly rigid member has a shape of a rectangular prism.

8. The substrate has a polygonal shape in a plan view; 4. The acceleration detecting device according to claim 3, wherein an outer shape of the frame-shaped high-rigidity member and a shape of the substrate are similar in plan view.

9. the high-rigidity member is a first high-rigidity member, 2. The acceleration detection device according to claim 1, further comprising at least one second high-rigidity member provided in a region overlapping with the acceleration detection element in a planar view, and extending in a direction connecting the second surface and the second main surface of the substrate within the second sealing portion of the sealing member.

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