Sensor-device connection structure

Abstract

A sensor-device connection structure is provided, comprising: a thin portion, thinner than other portions of a component; a flexible plate; at least one sensor device mounted on the flexible plate; a spacer, formed in the shape of a film having a uniform thickness, sandwiched between the thin portion and the flexible plate, and including a through portion formed at a position corresponding to the at least one sensor device along the thickness direction of the spacer; and an adhesive, filled in the through portion, and bonding the thin portion and the flexible plate together.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a sensor-device connection structure that connects a sensor device to a member. BACKGROUND

[0002] Hitherto, there has been a structure obtained by forming a protrusion on a bottom surface of a recess formed in a housing, filling an adhesive in the recess, placing a glass base that is linked to a sensor device on the protrusion, pressing the glass base from above, and curing the adhesive to fix the glass base (see Japanese Patent Application Laid-Open No. H6-186104). According to Japanese Patent Application Laid-Open No. H6-186104, the glass base is supported in a horizontal posture with its bottom surface partially overlapping the protrusion, and the adhesive is filled in a surface region outside the protrusion without a gap between the bottom surface of the glass base and the bottom surface of the recess. SUMMARY

[0003] In this case, when connecting a sensor device mounted on a flexible board to a thin portion of a member, it is difficult to form a protrusion on the flexible board or the thin portion because the flexible board and the thin portion are thin. Even when the protrusion can be formed, it is difficult to ensure dimensional accuracy of the protrusion. Therefore, the structure disclosed in Japanese Patent Application Laid-Open No. H6-186104 cannot be adopted, and thus it is difficult to ensure a thickness of an adhesive for connecting the sensor device due to the protrusion.

[0004] The present disclosure is made to solve the above problems, and a main object thereof is to ensure a thickness of an adhesive in a sensor-device connection structure that connects a sensor device mounted on a flexible board to a thin portion of a member.

[0005] According to one embodiment of the present disclosure, there is provided a sensor-device connection structure including:

[0006] a thin portion that is thinner than other portions of a member;

[0007] a flexible board;

[0008] at least one sensor device mounted to the flexible board;

[0009] a spacer,

[0010] formed in a film shape having a uniform thickness,

[0011] sandwiched between the thin portion and the flexible board, and

[0012] including a through portion that penetrates the spacer in a thickness direction of the spacer at a position corresponding to the at least one sensor device; and

[0013] an adhesive,

[0014] is filled in the through portion, and

[0015] The thin portion and the flexible plate are joined to each other.

[0016] In the above structure, at least one sensor device is mounted to the flexible plate. The spacer is formed in a film shape having a uniform thickness, and is interposed between the thin portion and the flexible plate. Therefore, in a state where the flexible plate is pressed against the thin portion by the spacer, the distance between the thin portion and the flexible plate is equal to the thickness of the spacer. Therefore, the distance can be adjusted by adjusting the thickness of the spacer.

[0017] Further, a through portion is formed through the spacer in a thickness direction of the spacer at a position corresponding to the at least one sensor device. In this case, an adhesive filled in the through portion joins the thin portion and the flexible plate to each other. Therefore, by injecting the adhesive into the through portion, and then pressing the flexible plate against the thin portion by the spacer, the thickness of the adhesive is equal to the thickness of the spacer. In other words, the thickness of the adhesive can be ensured by the thickness of the spacer. Therefore, when the at least one sensor device mounted to the flexible plate is connected to the thin portion of the member, the thickness of the adhesive can also be ensured.

[0018] Further, the spacer can include another through portion formed through the spacer in the thickness direction of the spacer at a position not corresponding to the at least one sensor device. With such a structure, when a portion of the flexible plate not corresponding to the at least one sensor device is also joined to the thin portion, the thickness of the adhesive can also be ensured at the non-corresponding portion.

[0019] Further, the thin portion can be formed in a ring shape, and the flexible plate and the spacer can be formed annularly along the thin portion. With such a structure, when the flexible plate is joined in conformity with the shape of the thin portion, the thickness of the adhesive can be ensured at the joining portion.

[0020] Further, in the spacer, the shape and size of the through portion formed at the position corresponding to the at least one sensor device, and the shape and size of the other through portion formed at the position not corresponding to the at least one sensor device, can be identical to each other. In such a structure, in the spacer, the through portions having the same shape and the same size are formed at both the position corresponding to the at least one sensor device and the position not corresponding to the at least one sensor device. Therefore, the through portions can be easily formed (i.e., manufactured), and the shape and size of the through portions can be easily managed.

[0021] Further, the at least one sensor device can be formed as an electronic circuit pattern on the flexible plate. With such a structure, a process of joining or soldering the at least one sensor device to the flexible plate can be omitted. Therefore, the at least one sensor device can be easily mounted to the flexible plate.

[0022] Further, the at least one sensor device can include a plurality of sensor devices, and the through portion of the spacer can include a plurality of through portions formed through the spacer in the thickness direction of the spacer at positions respectively corresponding to the plurality of sensor devices. With such a structure, when the plurality of sensor devices are connected to the thin portion, the thickness of the adhesive can be ensured in all of the corresponding through portions of the plurality of through portions.

[0023] Further, the through portion can communicate with the outside of the spacer. With such a structure, excess adhesive can be squeezed out from the portion of the through portion that communicates with the outside of the spacer. BRIEF DESCRIPTION OF DRAWINGS

[0024] In the drawings:

[0025] Figure 1 is a sectional view of a sensor-device connection structure;

[0026] Figure 2 is a bottom view of a flexible board assembly;

[0027] Figure 3 is a sectional view taken from the direction indicated by arrow 3-3 in Figure 2

[0028] Figure 4 is a bottom view showing a modification of the flexible board assembly;

[0029] Figure 5 is a bottom view showing another modification of the flexible board assembly;

[0030] Figure 6 is a bottom view showing still another modification of the flexible board assembly;

[0031] Figure 7 is a bottom view showing still another modification of the flexible board assembly;

[0032] Figure 8 is a bottom view showing still another modification of the flexible board assembly;

[0033] Figure 9 is a sectional view showing a modification of the sensor-device connection structure;

[0034] Figure 10 is a sectional view showing another modification of the sensor-device connection structure;

[0035] Figure 11 is a sectional view showing still another modification of the sensor-device connection structure;

[0036] Figure 12 is a bottom view showing still another modification of the flexible board assembly. DETAILED DESCRIPTION​

[0037] A first embodiment of a sensor-device connecting structure for connecting a sensor device to a strain wave transmission device provided at a joint of a robot is described below with reference to the drawings.

[0038] As shown in FIG. 1, the sensor-device connecting structure 10 includes a member 20, a flexible board assembly 30, and an adhesive 60. Figure 1

[0039] The member 20 is, for example, a flexible gear, a link member, or a housing included in a strain wave transmission device (a speed reducer), and includes a thick portion 20a and a thin portion 20b.

[0040] As shown in FIG. 2, the flexible board assembly 30 includes a flexible board 31, a sensor device 40, and a spacer 50. Figures 1 to 3

[0041] The flexible board 31 is a publicly known flexible printed circuit (FPC). For example, the flexible board 31 is formed by forming an adhesive layer on a base material film as an insulator in a thin film shape, by applying a conductor pattern (for example, a conductive foil) on the adhesive layer, and by covering a portion other than a terminal portion and a soldering portion with an insulating cover layer made of polyimide or the like. The thickness of the flexible board 31 is, for example, 0.1 [mm] to 0.5 [mm].

[0042] The sensor device 40 is a sensor device such as a torque sensor (more specifically, a strain gauge), a vibration sensor, a temperature sensor, a pressure sensor, or an optical sensor. The sensor device 40 includes a device portion and a lead (for example, a wire) extending from the device portion, which is soldered (for example, surface-mounted) to a soldering portion of the flexible board 31. In other words, the sensor device 40 is mounted on the flexible board 31. Although the shape of the sensor device 40 is illustrated here as a disc shape, the sensor device 40 can be formed in an arbitrary shape.

[0043] The spacer 50 is obtained by forming, for example, polyimide or an insulating resin such as a fluororesin in the shape of a film having a uniform thickness. The thickness of the spacer 50 is, for example, in the range of 0.05 [mm] to 0.2 [mm] depending on the type of the sensor device 40 and the thickness of the adhesive 60 to be adjusted. The spacer 50 is attached to one surface on the side opposite to the side on which the surface of the flexible board 31 on which the sensor device 40 is connected among the surfaces of the flexible board 31. In a state where the flexible board assembly 30 is connected to the thin portion 20b of the member 20, the spacer 50 is sandwiched between the thin portion 20b and the flexible board 31. Note that when the material of the cover layer of the flexible board 31 and the material of the spacer 50 are the same as each other, the spacer 50 can be formed integrally with the cover layer.

[0044] ​​A through-hole 51 is formed through the spacer 50 in the thickness direction of the spacer 50. The through-hole 51 (i.e., the through portion) is formed larger than the sensor device 40 and surrounds the sensor device 40 when viewed from the bottom. In other words, the through-hole 51 is formed at a position corresponding to the sensor device 40 (i.e., a position overlapping the sensor device 40). Although the shape of the cross section of the through-hole 51 is shown as a square in this document, the through-hole 51 can be formed in any shape. When the through-hole 51 is formed in this way larger than the sensor device 40, the sensor device 40 can sense the thin portion 20b only via the adhesive 60 for the spacer 50. Thus, the uniformity of sensing can be improved to be higher than a case where sensing is performed via a plurality of members made of different materials for the spacer 50.

[0045] The adhesive 60 is, for example, a thermosetting adhesive. The adhesive 60 is filled so as to fill the through-hole 51 of the spacer 50. The adhesive 60 is cured by heating, thereby joining the thin portion 20b of the member 20 and the flexible board 31 to each other. Note that the adhesive 60 can be, for example, a room-temperature-curing adhesive or a two-component adhesive.

[0046] Next, a process of connecting the sensor device 40 to the thin portion 20b of the member 20 (manufacturing method of the sensor-device connection structure) is described. The following process can be performed by an operator or can be performed by a production machine such as a robot.

[0047] First, the flexible board 31 formed with a predetermined conductor pattern is prepared.

[0048] Then, the lead of the sensor device 40 is soldered to the soldering portion of the flexible board 31. In other words, the sensor device 40 is mounted (i.e., connected) to the upper surface (also referred to as a "first surface") of the flexible board 31.

[0049] Next, the spacer 50 is attached (i.e., firmly fitted or joined) to the lower surface (also referred to as a "second surface" on the side opposite to the side on which the first surface is present) of the flexible board 31. At this time, the spacer 50 is arranged with respect to the flexible board 31 so that the center of the through-hole 51 of the spacer 50 and the center of the sensor device 40 are aligned with each other when viewed from the bottom. In this way, the flexible board assembly 30 is completed.

[0050] After that, the adhesive 60 is injected into the through-hole 51. At this time, the through-hole 51 is filled with the adhesive 60 so that no gap is formed.

[0051] Then, the spacer 50 is pressed against the thin portion 20b of the member 20, specifically, at a position where the flexible plate assembly 30 is connected. In other words, the flexible plate 31 is pressed against the thin portion 20b by the spacer 50. In this state, the thickness of the adhesive 60 is equal to the thickness of the spacer 50. At this time, the excess adhesive 60 can be squeezed out from the through-hole 51.

[0052] Next, the member 20 and the flexible plate assembly 30 are heated to cure the adhesive 60. Thus, the sensor-device connection structure 10 is completed (i.e., manufactured).

[0053] The above-described embodiments provide the following advantages.

[0054] The sensor device 40 is mounted on the flexible plate 31. The spacer 50 is formed in the shape of a film having a uniform thickness, and is sandwiched between the thin portion 20b and the flexible plate 31. Therefore, in a state where the flexible plate 31 is pressed against the thin portion 20b by the spacer 50, the distance between the thin portion 20b and the flexible plate 31 is equal to the thickness of the spacer 50. Thus, the distance can be adjusted by adjusting the thickness of the spacer 50.

[0055] The through-hole 51 is formed through the spacer 50 in the thickness direction of the spacer 50 at a position overlapping the sensor device 40. Further, the adhesive 60 filled in the through-hole 51 joins the thin portion 20b and the flexible plate 31 to each other. Therefore, by injecting the adhesive 60 into the through-hole 51, and then pressing the flexible plate 31 against the thin portion 20b by the spacer 50, the thickness of the adhesive 60 is equal to the thickness of the spacer 50. In other words, thanks to the thickness of the spacer 50, the thickness of the adhesive 60 can be ensured. Thus, when connecting the sensor device 40 mounted on the flexible plate 31 to the thin portion 20b of the member 20, the thickness of the adhesive 60 can also be ensured. Further, it is easy to homogenize the thickness of the film-shaped spacer 50, and thus the thickness of the adhesive 60 can be stabilized in products of mass production. Further, it is easy to properly manage the joining strength and the distance between the thin portion 20b and the sensor device 40.

[0056] Note that the above-described embodiments can be modified as follows. The same parts as those of the above-described embodiments are denoted by the same reference numerals to omit repetitive description thereof.

[0057] As Figure 4As shown, a groove 52 can be formed in the spacer 50 to communicate with the through hole 51. With this structure, even when a large amount of adhesive 60 is injected into the through hole 51, excess adhesive 60 can be squeezed out through the groove 52 when the spacer 50 is pressed against the thin portion 20b. Note that the width of the groove 52 is smaller than the width of the through hole 51, so the viscous adhesive 60 is unlikely to be squeezed into the groove 52 before filling the interior of the through hole 51. Therefore, the interior of the through hole 51 is easily filled with adhesive 60, and adhesive 60 is unlikely to remain in the thickness direction of the spacer 50. Thus, the thickness of the adhesive 60 can be further stabilized.

[0058] like Figure 5 As shown, an adhesive pool 54, which serves as a through-hole not communicating with the outside, can be formed in the spacer 50, and the through-hole 51 and the adhesive pool 54 are connected to each other via a groove 53. With this structure, even when a large amount of adhesive 60 is injected into the through-hole 51, excess adhesive 60 can be squeezed out into the adhesive pool 54 through the groove 53 when the spacer 50 is pressed against the thin portion 20b. Therefore, the interior of the through-hole 51 is easily filled with adhesive 60, and adhesive 60 is unlikely to remain in the thickness direction of the spacer 50. Thus, the thickness of the adhesive 60 can be further stabilized. Note that the groove 53 can be omitted so that the through-hole 51 and the adhesive pool 54 are directly connected to each other. In this case, the width of the adhesive pool 54 is smaller than the width of the through-hole 51, so the viscous adhesive 60 is unlikely to be squeezed out into the adhesive pool 54 before filling its interior. Therefore, similar functionality and advantages as with the case where the groove 53 is formed are provided.

[0059] like Figure 6 As shown, the flexible board assembly 30 (i.e., the sensor-device connection structure 10) may include a plurality of sensor devices 40, and a plurality of through holes 51 may be formed through the spacer 50 in the thickness direction at positions corresponding to the plurality of sensor devices 40. With this structure, when the plurality of sensor devices 40 are connected to the thin portion 20b, the thickness of the adhesive 60 can be ensured in each of the corresponding through holes 51. Furthermore, since the adhesive 60 is injected into the plurality of through holes 51, it can be said that the adhesive 60 is accurately positioned relative to each of the plurality of sensor devices 40 using the plurality of through holes 51. Furthermore, since the flexible board assembly 30 includes a plurality of sensor devices 40, it can be said that wiring for the plurality of sensor devices 40 can be uniformly performed using the flexible board 31.

[0060] like Figure 7As shown, other through holes 55 can be formed in the thickness direction of the spacer 50 at locations that do not overlap with the sensor device 40 (i.e., through portions). With this structure, when portions of the flexible plate 31 that do not correspond to the sensor device 40 are also bonded to the thin portion 20b, the thickness of the adhesive 60 can be ensured in these non-corresponding portions. Furthermore, when portions that do not correspond to the sensor device 40 are not bonded to the thin portion 20b, the flexible plate 31 may peel off from the thin portion 20b. However, by bonding the portions that do not correspond to the sensor device 40 to the thin portion 20b, this phenomenon can be suppressed. Thus, the vibration of the peeled flexible plate 31 that affects the detection of the sensor device 40 can be suppressed. In addition, in the spacer 50, the shape and size of the through holes 51 formed at locations overlapping with the sensor device 40 and the shape and size of the other through holes 55 formed at locations not overlapping with the sensor device 40 are the same. In this structure, through holes 51 and 55 with the same shape and size are formed in the spacer 50 at positions corresponding to and not corresponding to the sensor device 40. Therefore, unlike cases where through holes with different shapes and sizes are formed at positions corresponding to and not corresponding to the sensor device 40, a common means for forming the through holes can be used. Thus, through holes 51 and 55 can be easily formed, and their shapes and sizes can be easily managed. Furthermore, when the thicknesses of through holes 51 and 55 are the same, the amount of adhesive 60 injected into them can be equal, allowing the same amount of adhesive 60 to be injected into each of them. In other words, productivity can be improved. Note that the shapes of through holes 51 and 55 can be different. Furthermore, the sizes of through holes 51 and 55 can be different.

[0061] like Figure 8 As shown, a cutout 57 can be formed in the spacer 50 instead of a through hole 51. The cutout 57 (i.e., the through portion) is formed to open the spacer 50 in the thickness direction. The cutout 57 is formed at a position in the spacer 50 that overlaps with the sensor device 40 and communicates with the outside of the spacer 50. With this structure, a connection with... Figure 4 The structure shown has the same function and effect.

[0062] like Figure 9As shown, the flexible board assembly 130 can include a flexible board 131 in which the sensor device 140 is formed as an electronic circuit pattern. The sensor device 140 is formed, for example, by a resistance pattern and a conductor pattern, and is covered by a cover layer of the flexible board 131. In other words, the sensor device 140 is mounted in the flexible board 131. By such a structure, the joining or soldering of the sensor device 140 to the flexible board 131 can be omitted. Therefore, the sensor device 140 can be easily mounted in the flexible board 131. Further, the sensor device 140 can be formed as an electronic circuit pattern, for example, together with a wiring pattern (e.g., a conductor pattern) in the flexible board 131. Further, the sensor device 140 can be handled while being mounted in the flexible board 131, and thus the sensor device 140 can be easily handled.

[0063] As shown in FIG. 1, the sensor device 40 can be mounted in the flexible board 31. In this case, the sensor device 40 can be joined to the flexible board 31 by soldering or the like. In this case, the sensor device 40 can be mounted in the flexible board 31 by the joining or soldering. Therefore, the sensor device 40 can be easily mounted in the flexible board 31. Figure 10 As shown in FIG. 2, in the flexible board assembly 230, the sensor device 40 can be housed in the through-hole 51 of the spacer 50. In this case, the spacer 50 is sandwiched between the thin portion 20b and the flexible board 31, and the through-hole 51 is formed at a position overlapping the sensor device 40. Further, the adhesive 60 is filled in the through-hole 51 to join the thin portion 20b, the flexible board 31, and the sensor device 40 to each other.

[0064] As shown in FIG. 3, in the flexible board assembly 330, the spacer 50 can be sandwiched between the thin portion 20b and the sensor device 340. Specifically, a sensor-device connection structure can be provided, including: Figure 11 a thin portion, thinner than other portions of the member;

[0065] a flexible board;

[0066] at least one sensor device, mounted below the flexible board;

[0067] a spacer,

[0068] formed in a film shape having a uniform thickness,

[0069] sandwiched between the thin portion and the at least one sensor device, and

[0070] including a through portion formed through the spacer in a thickness direction of the spacer at a position corresponding to a portion of the at least one sensor device; and

[0071] an adhesive,

[0072] filled in the through portion, and

[0073] joining the thin portion and the at least one sensor device to each other.

[0074]

[0075] ​In the spacer 50, a through hole 51 is formed at a location overlapping a portion of the sensor device 340. Adhesive 60 bonds the thin portion 20b and the sensor device 340 together. In this structure, with the sensor device 340 pressed against the thin portion 20b by the spacer 50, the distance between the thin portion 20b and the sensor device 340 is equal to the thickness of the spacer 50. Therefore, by injecting adhesive 60 into the through hole 51 and then pressing the sensor device 340 against the thin portion 20b by the spacer 50, the thickness of adhesive 60 is equal to the thickness of the spacer 50. In other words, the thickness of adhesive 60 is ensured by the thickness of the spacer 50. Therefore, when the sensor device 340, mounted below the flexible plate 31, is connected to the thin portion 20b of the member 20, the thickness of adhesive 60 can also be ensured. Furthermore, the thickness of the film-like spacer 50 is easily uniformized, thus ensuring a stable thickness of adhesive 60 even in mass-produced products. Furthermore, the bonding strength and distance between the thin section 20b and the sensor device 340 can be easily and appropriately managed.

[0076] like Figure 12 As shown, the thin portion 20b can be formed in a ring shape, with a flexible plate 431 and a spacer 450 formed circumferentially along the thin portion 20b. The flexible plate assembly 430 (i.e., the sensor-device connection structure 10) includes a plurality of sensor devices 40, and a plurality of through holes 451 are formed in the thickness direction of the spacer 450 at positions corresponding to the plurality of sensor devices 40. With such a structure, when the flexible plate 431 is joined to the thin portion 20b in a shape consistent with the shape, the thickness of the adhesive 60 can be ensured at the joint. Furthermore, a groove 452 is formed in the spacer 450 to communicate with the outside of the spacer 450 and the through holes 451, and a groove 456 is formed in the spacer 450 to communicate with the outside of the spacer 450 and other through holes 455.

[0077] The thin portion 20b of component 20 is not necessarily a flat plate; it can also be a curved plate.

Claims

1. A sensor-device connection structure comprising: a thin portion that is thinner than other portions of the member; a flexible board that is a flexible circuit board; at least one sensor device mounted to the flexible board; a spacer, formed in a shape of a film having a uniform thickness, sandwiched between the thin portion and the flexible board, and including a through portion formed through the spacer in a thickness direction of the spacer at a position corresponding to the at least one sensor device; and an adhesive, filled in the through portion, and joining the thin portion and the flexible board to each other.

2. The sensor-device connection structure according to claim 1, wherein The spacer includes another through portion formed through the spacer in the thickness direction of the spacer at a position not corresponding to the at least one sensor device.

3. The sensor-device connection structure according to claim 1, wherein the thin portion is formed in a ring shape, and wherein the flexible board and the spacer are formed annularly along the thin portion.

4. The sensor-device connection structure according to claim 2, wherein In the spacer, a shape and a size of the through portion formed at the position corresponding to the at least one sensor device and a shape and a size of the other through portion formed at the position not corresponding to the at least one sensor device are identical to each other.

5. The sensor-device connection structure according to claim 1, wherein The at least one sensor device is formed as an electronic circuit pattern on the flexible board.

6. The sensor-device connection structure according to claim 1, wherein the at least one sensor device includes a plurality of sensor devices, and wherein the through portion of the spacer includes a plurality of through portions formed through the spacer in the thickness direction of the spacer at positions respectively corresponding to the plurality of sensor devices.

7. The sensor-device connection structure according to claim 1, wherein The through portion communicates with an outside of the spacer.

Images