Force sensor

The present invention relates to a force sensor, and particularly includes a shock absorber suitable for adjusting the ratio of the external force applied to the input portion of the sensor, which is transmitted to the chip and the portion transmitted to the fixed portion. Regarding force sensor.

Conventionally, Patent Document 1 has proposed a 6-axis force sensor. In this 6-axis force sensor, a buffer is provided around the 6-axis force sensor chip so that the magnitude of the external force applied to the external force application part (force action part) of the 6-axis force sensor chip made of a semiconductor substrate becomes small. A device is provided. As a result, the level of external force that can be measured by the 6-axis force sensor chip can be dramatically increased, and the range of application can be expanded. Further, this 6-axis force sensor can solve the problem of multi-axis interference even if it has a structure provided with a shock absorber. Further, the load detector described in Patent Document 2 is composed of an annular rigid body portion located on the outer periphery, a rigid body portion located in the central portion, and a load detection unit provided in the radial direction forming a portion connecting these. It is composed. By providing a hole, a notch, a groove, or the like with respect to the shape of the load detecting portion, it is possible to make the gains of each shaft component of the load to be detected uniform.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-254843</text></patcit><patcit num="2"><text>Japanese Patent Application Laid-Open No. 5-118943</text></patcit>

<p> In the above-mentioned force sensor, a semiconductor sensor chip to which semiconductor manufacturing technology is applied may be used as a part that is sensitive to a force or a moment. Since the semiconductor sensor chip uses a semiconductor substrate to form a part that receives an external force (force action part), there is an upper limit to the force that can be applied, and if a force or moment larger than necessary is applied, The chip of the semiconductor substrate may be damaged. Therefore, if the force is not transmitted to the chip at all, the force cannot be detected. Therefore, the external force is appropriately attenuated so that the necessary and appropriate external force applied to the input portion of the sensor can be transmitted to the chip. It is desirable to attach a shock absorber having an external force damping mechanism.</p><p> The external force damping performance of the shock absorber by the external force damping mechanism has been conventionally determined by manufacturing a complicated shape, drilling, or the like with respect to the shape and structure of the external force damping mechanism. However, in general, it has not been easy to adjust the damping characteristics of the damping mechanism.</p><p> Further, in the connection portion between the shock absorber and the force sensor chip, a part of the external force is applied from the external force transmission portion of the shock absorber to the force acting portion of the force sensor chip through the joint surface between the two. Usually, the chip pedestal portion that supports and fixes the force sensor chip is fixed by using the fixing portion of the shock absorber. Therefore, the application of an external force may cause deformation to the joint surface between the chip pedestal portion and the fixing portion of the shock absorber. As a result, according to the conventional force sensor provided with the shock absorber, there is a possibility that peeling may occur at the joint surface between the chip pedestal portion and the fixed portion of the shock absorber.</p><p> In view of the above problems, an object of the present invention is to sufficiently attenuate the external force applied to the force sensor chip and transmit it to the acting portion, and among the external forces applied to the input portion of the sensor by simple processing. It is an object of the present invention to provide a force sensor capable of adjusting the ratio of the force transmitted to the chip and the force transmitted to the fixed portion.</p><p> Further, in view of the above problems, another object of the present invention is to provide a structure between the fixing portion of the shock absorber and the chip pedestal portion so as to prevent the occurrence of a situation in which the joint surface between the two is peeled off. The purpose is to provide a force sensor to have.</p>

<p> The force sensor according to the present invention is configured as follows in order to achieve the above object.</p><p> The first force sensor (corresponding to claim 1) is a force sensor including a force sensor chip that detects an external force and a shock absorber that attenuates the external force and applies it to the force sensor chip. The shock absorber has a disk-shaped damping mechanism portion that damps an external force, and is characterized in that an annular groove is formed at least on the surface of the damping mechanism portion.</p><p> In the above-mentioned force sensor, it is possible to manufacture a force sensor with a high degree of freedom in designing sensor performance and high reproducibility of sensor performance by processing an annular groove into a disk-shaped damping mechanism. Become. Further, by grooving the surface, when an external force is applied to the input portion, the fulcrum on which the external force acts can be brought closer to the tip acting portion, and each axial component of the external force is effectively transmitted to the chip acting portion. It can be made easier.</p><p> The second force sensor (corresponding to claim 2) has the same configuration as the first force sensor described above, and is characterized in that an annular groove is formed only on the back surface of the damping mechanism portion. ..</p><p> The third force sensor (corresponding to claim 3) is characterized in that, in the above configuration, the damping mechanism portion is preferably disk-shaped.</p><p> In the above configuration, the fourth force sensor (corresponding to claim 4) is preferably a disk-shaped damping mechanism portion in which an annular groove is formed on the front surface and an annular groove is formed on the back surface. It is characterized by. A mechanism that easily produces a damping action can be realized simply by grooving the front and back surfaces of the disk-shaped damping mechanism, resulting in a high degree of freedom in designing sensor performance and reproducibility of sensor performance. It is possible to manufacture a high force sensor. Further, by applying groove processing to the surface, when an external force is applied to the input portion, the fulcrum on which the external force acts can be brought closer to the tip acting portion, and each axial force component of the external force can be effectively applied to the tip acting portion. It can be easily transmitted, and the fulcrum of the force applied to the damping mechanism by grooving the back surface is separated from the joint surface between the chip pedestal and the fixed part of the shock absorber, so it is difficult for the force to be transmitted to the joint surface. Therefore, peeling of the joint surface can be prevented.</p><p> In the above configuration, the fifth force sensor (corresponding to claim 5) preferably has a disc-shaped damping mechanism portion and an annular groove on the surface inside the disc-shaped damping mechanism portion in the radial direction. The annular groove on the back surface is the radial outside of the disc-shaped damping mechanism.</p><p> In the sixth force sensor (corresponding to claim 6), preferably, the shock absorber has an external force input unit that receives an external force, and the external force input unit is connected to the central portion of the damping mechanism unit. The annular groove formed in the damping mechanism portion is characterized in that it is formed in a region around the external force input portion.</p><p> In the above configuration, the seventh force sensor (corresponding to claim 7) preferably has a shock absorber having an external force input unit that receives an external force, and the external force input unit is connected to a central portion of the surface of the damping mechanism unit. The annular groove formed on the front surface of the damping mechanism portion and the annular groove formed on the back surface are both characterized in that they are formed in a region around the external force input portion. </p><p> In each of the above configurations, the eighth force sensor (corresponding to claim 8) preferably has an annular groove such that the tip of the force sensor has an inclination direction with respect to the central axis of the disk-shaped damping mechanism portion. It is characterized in that it is formed by inclining the groove side wall so as to face it.</p><p> The ninth force sensor (corresponding to claim 9) is characterized in that, in each of the above configurations, the annular groove is preferably an annular shape.</p>

<p> According to the present invention, in a force sensor including a force sensor chip and a shock absorber provided with a damping mechanism, the damping mechanism is preferably disc-shaped, and for example, an annular groove is formed on the front and back surfaces thereof. Since the mechanical portion that produces the damping action is formed only by grooving, the damping force can be adjusted only by changing the design in the depth direction of the groove. Further, the sensor performance of the force sensor can be adjusted by appropriately controlling the grooving. Further, the damping mechanism unit according to the purpose can be easily manufactured with good reproducibility. According to the structure of the force sensor of the present invention, with respect to the coupling structure between the fixed portion of the shock absorber and the chip pedestal, the main portion of the applied external force is transmitted through a portion other than the coupling portion. It is possible to prevent the occurrence of a situation in which the joint surface between the two is peeled off.</p>

Hereinafter, preferred embodiments (Examples) of the present invention will be described with reference to the accompanying drawings.

The force sensor according to the present invention is a force sensor chip that detects the external force in response to an external force (axial force) applied from the outside, and a force sensor chip that attenuates the applied external force by a predetermined amount. It is composed of a shock absorber including a damping mechanism unit (buffer mechanism unit) that transmits to. The force sensor according to this embodiment preferably has a "disk-shaped" appearance.

The force sensor chip used in this embodiment is manufactured using a semiconductor substrate and functions as a 6-axis force sensor. The 6-axis force sensor has a sensor function that detects forces and moments for each of the three orthogonal axes (X-axis, Y-axis, and Z-axis).

The force sensor according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view showing the appearance of the force sensor 100, and FIG. 2 is a cross-sectional perspective view showing the internal structure of the force sensor 100.

The force sensor 100 includes a force sensor chip 11 and a shock absorber 12. An example of the configuration of the force sensor chip 11 is shown in FIGS. 3 and 4. Before explaining the configuration of the force sensor 100, an example of the configuration of the force sensor chip 11 will be described with reference to FIGS. 3 and 4. The force sensor chip 11 is configured to detect an external force by using a strain resistance element.

FIG. 3 shows a perspective view of the force sensor chip 11, and FIG. 4 shows a plan view of the force sensor chip 11. The force sensor chip 11 is a semiconductor sensor element formed by applying semiconductor manufacturing process technology using a semiconductor substrate. The planar shape of the force sensor chip 11 is preferably square and has a flat plate shape. In FIG. 3 showing the planar shape of the force sensor chip 11, the force sensor chip 11 has a substantially square-shaped working portion 21 located in the center and a peripheral position surrounding the working portion 21. The square ring-shaped support portion 22 located in the above, and the four T-shaped connecting portions 23A, 23B, 23C, which are located between the working portion 21 and the supporting portion 22 and connect the two corresponding to each of the four sides. It consists of 23D. Each of the four connecting portions 23A to 23D is a T-shaped beam and has a bridge portion and an elastic portion. Each of the four T-shaped connecting parts 23A to 23D has three strain resistance elements (Sxa1, Sxa2, Sxa3), preferably on one surface (surface 24) at the boundary connected to the working part 21. (Sxb1, Sxb2, Sxb3), (Sya1, Sya2, Sya3), (Syb1, Syb2, Syb3) are arranged.

As shown in FIG. 3, the working portion 21, the supporting portion 22, and the connecting portions 23A to 23D are formed by eight through holes 25a to 25h provided in the force sensor chip 11. The through holes 25a to 25h cause deformation of the connecting portions 23A to 23D and displacement of the acting portion 21 according to the external force applied to the acting portion 21, and the formation position and shape thereof so that the force can be detected with high accuracy. Has been adjusted.

In FIGS. 3 and 4, the X-axis, Y-axis, and Z-axis that are orthogonal to the force sensor chip 11 are defined as shown in the figure. In FIG. 3, "upper", "lower", "right", and "left" in the force sensor chip 11 are defined for convenience. In FIG. 4, the horizontal axis is shown as the X-axis and the vertical axis is shown as the Y-axis. Further, in FIG. 3, the forces and moments related to each axis are indicated by arrows and symbols. For the three axes of the Cartesian coordinate system (X-axis, Y-axis, Z-axis), the force in the X-axis direction is Fx, the force in the Y-axis direction is Fy, the force in the Z-axis direction is Fz, and with respect to the X-axis. Let Mx be the moment given in the rotational direction, My be the moment given in the rotational direction with respect to the Y axis, and Mz be the moment given in the rotational direction with respect to the Z axis.

The above 6-axis components (axial forces), that is, Fx [N], Fy [N], Fz [N], Mx [N cm], My [N cm], Mz [N cm] are the support parts. When 22 is directly applied to the acting portion 21 of the fixed force sensor chip 11, the connecting portions 23A to 23D are deformed according to the applied force. Distortion resistance elements (Sxa1, Sxa2, Sxa3), (Sxb1, Sxb2, Sxb3), (Sya1, Sya2, Sya3), (Syb1, Syb2, Syb3) are distorted according to the deformation of the connecting portions 23A to 23D. The magnitude and direction of the 6-axis force can be detected by analyzing the signals from the elements (Sxa1, Sxa2, Sxa3), (Sxb1, Sxb2, Sxb3), (Sya1, Sya2, Sya3), (Syb1, Syb2, Syb3). ..

In the actual force sensor chip 11, a plurality of electrodes and wiring for connecting the electrodes and each strain resistance element are provided on the peripheral portion of the chip, but these are not the main parts of the present invention. The illustration is omitted in FIGS. 3 and 4.

Next, the structure of the force sensor 100 will be described with reference to FIGS. 1 and 2.

As described above, the force sensor 100 is composed of the force sensor chip 11 and the shock absorber 12. The shock absorber 12 has a cylindrical rod-shaped input unit 101 to which an external force F1 applied from the outside is directly applied, and a relatively flat structure having a short axial length for fixing the force sensor 100 at a required location. A bottom cylindrical sensor fixing portion 102, a ring-shaped chip pedestal 103 for attaching a force sensor chip 11, a disk-shaped damping mechanism portion 104 having a damping function (or buffering function), and an input portion 101. It is composed of a transmission unit 105 that connects the action unit 21 of the force sensor chip 11.

The above-mentioned external force F1 is one of the above-mentioned 6-axis components (Fx, Fy, Fz, Mx, My, Mz).

The sensor fixing portion 102 has a bottom portion 102a and a cylindrical portion 102b. The chip pedestal 103 for fixing the force sensor chip 11 is fixed to the upper surface of the bottom 102 of the sensor fixing portion 102 via a ring-shaped protrusion 102a-1. As shown in FIG. 2, the chip pedestal 103 can be made as a member different from the sensor fixing portion 102, or can be made as a part of the sensor fixing portion 102.

The support portion 22 of the force sensor chip 11 described above is fixed to the ring-shaped chip pedestal 103.

The disk-shaped damping mechanism portion 104 and the disk-shaped chip pedestal 103 are arranged in a parallel positional relationship at relatively close positions. Both the disk-shaped damping mechanism portion 104 and the chip pedestal 303 have a hole formed in the center thereof. The input unit 101, the sensor fixing unit 102, and the damping mechanism unit 104, which are made as separate parts, are combined and combined. The cylindrical rod-shaped input portion 101 is inserted into and fixed in the hole at the center of the disc-shaped damping mechanism portion 104. The disk-shaped damping mechanism portion 104 is fixed to the opening on the upper side of the cylindrical portion 102b of the sensor fixing portion 102.

The force sensor chip 11 is fixed at a position above the chip pedestal 103 in the hole in the center of the circular chip pedestal 103. The rod-shaped transmission unit 105 connects the lower surface of the input unit 101 with the action unit 21 of the force sensor chip 11.

In the disk-shaped damping mechanism portion 104, circular ring-shaped grooves 31, 32 are preferably formed on the upper surface (front surface) and the lower surface (back surface) in FIG. 2 and the like by grooving. The two circular ring-shaped grooves 31, 32 are formed in a concentric positional relationship around the common central axis 33 of the input portion 101 and the damping mechanism portion 104. The inner peripheral wall surface and the outer peripheral wall surface of each of the grooves 31 and 32 are formed to be inclined, and the bottom surface is formed to be curved. The inner and outer peripheral wall surfaces of the grooves 31 and 32 are inclined with respect to the central axis of the damping mechanism portion 104 and the like, and the inclined direction is directed toward the force sensor chip 11 located downward. It is tilted. As a result, the cross-sectional shape of the portion formed between the groove 31 and the groove 32 is substantially N-shaped when viewed from the cross section of the left portion in FIG.

The damping mechanism portion 104 has a disk shape, and grooves 31 and 32 are formed on the upper and lower surfaces thereof by grooving to enhance the deformability corresponding to the external force F1 and to attenuate the external force F1 to make a part of the external force F1. It is applied to the working part 21 of the force sensor chip 11. In the damping mechanism unit 104, the sensitivity performance (detection performance) to the external force F1 can be adjusted by adjusting the depths (depths in the inclination direction) of the grooves 31 and 32 by grooving the upper and lower surfaces. Further, by grooving the upper surface, when an external force is applied to the input portion, the center of displacement of the input portion can be brought closer to the tip acting portion, and each axial force component of the external force can be effectively applied to the tip acting portion. It can be easily transmitted.

In the force sensor 100 according to the above embodiment, the main portion of the external force F1 applied to the input unit 101 is transmitted to the damping mechanism unit 104, and a part thereof is transmitted to the force sensor chip 11 via the transmission unit 105. It is transmitted and applied to the working part 21 of. The force sensor chip 11 is sensitive to a part of the external force F1 that has been attenuated to generate a deformed state, and the external force F1 is detected by the strain resistance element described above.

In the above damping mechanism portion 104, it is preferable to form grooves 31 and 32 on the upper and lower surfaces, but the groove formed in the damping mechanism portion 104 is only the groove 31 on the front surface only or the groove on the back surface from the viewpoint of adjusting the damping force. It may be only 32.

According to the force sensor 100 according to the present embodiment, the external force F1 is effectively attenuated and transmitted to the center of the force sensor chip 11 by forming the grooves 31 and 32 in the disk-shaped damping mechanism portion 104. Further, the detection performance can be easily adjusted by changing the depth of the groove in the inclination direction. Further, since the components of the damping mechanism portion 104 are formed of individual parts, mass production can be performed only by changing the design according to the specifications.

The input unit 101, sensor fixing unit 102, chip pedestal 103, damping mechanism unit 104, and transmission unit 105 of the force sensor 100 are generally made of metal (aluminum, carbon steel, stainless steel, etc.), plastic, ceramics, glass, etc. It is made of solid material.

In the above, two or more kinds of metals may be used, but considering the manufacturing process and cost, one kind of metal is used to form a sensor housing such as an input part and a sensor fixing part, and further shape, It is more realistic to adjust the deformation action by the size, the way of forming grooves, holes, etc.

Further, the chip pedestal 103 is preferably provided with insulating properties, particularly from the viewpoint of maintaining high sensor accuracy as the force sensor 100, and a material having a thermal expansion coefficient close to that of the force sensor chip 11 is desirable. If the coefficient of thermal expansion is not close, the force sensor chip 11 may be stretched due to an external temperature change. This causes an error (temperature drift) in the detection by the force sensor 100. In order to extract the detection signal from the force sensor 100, a bias voltage is usually applied to eliminate the influence of noise. However, in order to prevent the bias voltage from being applied to other parts, it is desirable that the chip pedestal 103 has an insulating property. From this point of view, ceramics and glass are suitable.

Further, since the chip pedestal 103 is bonded to the cylindrical portion 102b of the sensor fixing portion 102 and the force sensor chip 11 by anodic bonding, it is particularly desirable to select glass. In addition, instead of the anode bonding, an adhesive such as an epoxy resin-based adhesive can be used as in the conventional case. Depending on how the sensor is used, a phenolic adhesive having excellent heat resistance may be used.

Next, the force sensor 200 according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional perspective view showing the internal structure of the force sensor 200, and is the same as FIG. 2. In FIG. 5, elements that are substantially the same as the elements described in FIG. 2 are designated by the same reference numerals.

The force sensor 200 includes a force sensor chip 11 and a shock absorber 12. The shock absorber 12 is a relatively flat cylinder having a short axial length for fixing a cylindrical rod-shaped input unit 201 to which an external force F1 applied from the outside is directly applied and a force sensor 200 at a required location. A sensor fixing unit 202 having a shape, a disk-shaped chip pedestal 203 for attaching a force sensor chip 11, a disk-shaped damping mechanism unit 104 having a damping function (buffering function), an input unit 201, and a force sensor. It is composed of a transmission unit 105 that connects the working unit 21 of the sensor chip 11. The disk-shaped chip pedestal 203 has a hole formed in the center thereof. The force sensor chip 11 is fixed to the portion of the hole in the center of the circular chip pedestal 203 at a position below (outside) the chip pedestal 203. The rod-shaped transmission unit 105 is arranged through the hole of the chip pedestal 203, and connects the lower surface of the input unit 101 and the action unit 21 of the force sensor chip 11.

The damping mechanism unit 104 in the force sensor 200 has a shape having grooves 31 and 32 as described in the first embodiment, and has a function of attenuating the external force F1 and giving a part thereof to the force sensor chip 11. Have.

In the force sensor 100 of the first embodiment described above, the chip pedestal 103 and the external force transmission unit 105 are in contact with different sides (front and back) of the force sensor chip 11 (double-sided joint). Structure), in the force sensor 200 of the second embodiment, the chip pedestal 203 and the transmission unit 105 are in contact with the force sensor chip 11 on the same side (single-sided joint structure). Conventionally, in the double-sided joint structure, since the joint surface between the chip pedestal and the fixed portion of the shock absorber is separated from the damping mechanism, there is no risk of the joint surface peeling off, but in the single-sided joint structure, the chip pedestal and the shock absorber Since the joint surface of the fixed portion is close to the damping mechanism portion, there is a risk of peeling. However, even in the single-sided joint structure, by grooving the lower surface of the damping mechanism, the center of deformation of the damping mechanism is separated from the joint surface of the chip pedestal and the fixed portion of the shock absorber, so that the force is transmitted to the joint surface. It becomes difficult to be removed, and peeling of the joint surface can be prevented.

Further, by adopting a layout like the shock absorber 12 shown in FIG. 5, all the components of the shock absorber 12 are on the same side with respect to the force sensor chip 11 (in FIG. 5, the force sensor). (Upper side of the chip 11), input unit 201, damping mechanism unit 104, sensor fixing unit 202, transmission unit 105, and chip pedestal 203 can be integrally formed, and then the force sensor chip 11 can be attached later. It will be possible. This contributes to simplification of the manufacturing process of the force sensor 200. Integrally forming a part or all of the portion from the input portion 201 to the damping mechanism portion 104 leads to a reduction in the amount of the adhesive used and can increase the robustness.

In addition, the force sensor 200 has been made even thinner in the vertical direction. In the force sensor 200, in order to reduce the thickness, the transmission unit 105, the damping mechanism unit 104, and the chip pedestal 203 are arranged on the same surface side of the force sensor chip 11, and further, the inner peripheral side of the sensor fixing unit 202. A damping mechanism unit 104 is provided in the chip pedestal 203, and a transmission unit 105 is provided on the inner peripheral side of the chip pedestal 203.

Next, the force sensor 300 according to the third embodiment of the present invention will be described with reference to FIGS. 6 to 8. The force sensor 300 according to the present embodiment is a force sensor configured by using the force sensor according to the second embodiment having a single-sided joint structure.

FIG. 6 is an external view of the force sensor 300, FIG. 7 is a cross-sectional perspective view showing a half-cut vertical section of the force sensor 300, and FIG. 8 is a vertical section in which the characteristic configuration of the force sensor 300 is clearly shown. It is a top view.

The force sensor 300 is composed of a housing upper portion 300A and a housing lower portion 300B. The upper part 300A of the housing and the lower part 300B of the housing are connected and integrated by a screw connection structure or a joint.

The upper portion 300A of the housing is attached to a disk-shaped damping mechanism portion 301 having a large diameter located in the central portion, an external force input portion 302 forming a columnar protrusion formed on the upper surface thereof, and a lower surface of the damping mechanism portion 301. It has a chip pedestal 303. The damping mechanism portion 301 and the external force input portion 302 are formed as an integral body, and a groove 304 on the outer side in the radial direction is formed around the root portion of the external force input portion 302 on the front surface side. A groove 305 on the inner side in the radial direction is formed on the lower surface (back surface side) of the damping mechanism portion 301. The groove 304 corresponds to the above-mentioned groove 31, and the groove 305 corresponds to the above-mentioned groove 32. By forming a thin portion by the two grooves 304 and 305, the damping function of the damping mechanism portion 301 is created. The chip pedestal 303 is prepared as a separate member for the damping mechanism unit 301 and the external force input unit 302. The peripheral edge of the chip pedestal 303 is joined to the lower surface of the damping mechanism section 301. A hole is formed in the central portion of the chip pedestal 303, and the force sensor chip 11 is fixed so as to face the hole. The central portion of the lower surface of the damping mechanism portion 301 is connected to the central acting portion 21 of the force sensor chip 11 via the transmission portion 306.

An external force receiving portion is attached to the external force input portion 302 via a connecting member or the like. Further, in the connected state between the upper portion 300A of the housing and the lower portion 300B of the housing, a space 311 is formed between them. The above-mentioned force sensor chip 11 will be arranged in the space 311.

The lower portion 300B of the housing is an element for fixing the force sensor 300 to a fixed member (not shown) to which the force sensor 300 should be fixed. The lower portion 300B of the housing is composed of a disk-shaped portion 312 connected to the upper portion 300A of the housing and a connecting portion 313 forming a columnar protrusion formed on the lower surface of the disk-shaped portion 312. The disk-shaped portion 312 and the connecting portion 313 are integrated. The connecting portion 313 is fixed to the fixed member via a connecting member (not shown).

According to the force sensor having the above structure, the external force F1 applied to the external force input unit 302 is attenuated by the damping action of the damping mechanism unit 301 of the upper portion 300A of the housing, and a part of the external force passes through the transmission unit 306. Then, it is given to the working part of the force sensor chip 11.

In FIG. 8, the cross-sectional region 330 including the upper groove 304 and the lower groove 305 in the damping mechanism portion 301 is a region that causes a damping action. The thickness direction dimension of this region 330 and the radial dimension at each thickness position can be appropriately changed according to the design of the sensor performance (detection performance, load bearing performance, etc.) of the force sensor 300. Further, for each of the upper groove 304 and the lower groove 305 in the damping mechanism portion 301, the sensor performance can be improved by changing the groove depth in the inclined direction, the radial position, and the position in the axial direction 33. That is, the detection performance can be significantly changed. In particular, the rated load can be easily adjusted by adjusting the depth of the groove in the inclined direction and the position where the thin portion is formed by the upper and lower grooves. As a result, the degree of freedom in design and the design efficiency of the force sensor 300 can be improved.

Next, with reference to Table 1 below, the detection performance of the force sensor according to the present invention (second embodiment) is compared with the detection performance of the force sensor of the conventional structure (flat plate shape).

<tables num="1"><img file="JP2008190865A_D0001.tif" /></tables>

In Table 1 above, the upper row shows the force sensor according to the second embodiment of the present invention, and the lower row shows the force sensor having a conventional structure (flat plate shape). In Table 1, each item of "shape", "detection performance evaluation (detection simulation by structural analysis)", and "detection performance ( or Δ)" is shown in the horizontal direction. In the detection performance evaluation column, the detection evaluation performance table is shown in both the second embodiment of the present invention and the conventional structure.

In the detection evaluation performance table in the case of the second embodiment of the present invention, each detection distortion is 27 μS or more as shown in block B1, sufficient signal strength is secured, and as shown in block B2, the others. Regarding axis interference, for example, 90/40 = 2.2 for My, and interference with other axes can be sufficiently reduced. Therefore, the detection performance of the force sensor according to the present invention is high. On the other hand, in the detection evaluation performance table in the case of the conventional structure, each detection distortion is 18 μS or more as shown in block B3, and regarding other-axis interference as shown in block B4, for example, for My. 140/35 = 4, and it is not possible to obtain sufficient detection performance with a force sensor with a conventional structure.

Next, with reference to Table 2 below, the detection performance of the force sensor according to the present invention will be examined from the viewpoint of design.

<tables num="2"><img file="JP2008190865A_D0002.tif" /></tables>

In Table 2 above, the upper part shows the structure of the force sensor according to the second embodiment of the present invention with a rating of 30N, and the lower part shows the structure of the same force sensor with a rating of 15N. In Table 2, each item of "design", "detection performance evaluation (detection simulation by structural analysis)", and "detection performance ( or Δ)" is shown in the horizontal direction. In the detection performance evaluation column, the detection evaluation performance table is shown in each case. The 15N rated force sensor adjusts the rating of the force sensor by deepening the groove on the surface side located above the 30N rated force sensor.

In the detection evaluation performance table in the case of 30N rating, each detection distortion is 27 μS or more as shown in block B5, sufficient signal strength is secured, and as shown in block B6, regarding other axis interference, for example. For My, 90/40 = 2.2, which can sufficiently reduce interference on other axes. In the detection evaluation performance table for the 15N rating, each detection distortion is 26 μS or more as shown in block B7, and for other axis interference as shown in block B8, for example, 85/51 = for My. It becomes 1.6, and sufficient detection performance can be obtained even in this case.

As described above, it is possible to design a 15N rated load force sensor having good detection performance by changing the groove shape (depth, etc.) based on the design of the 30N rated load force sensor. Therefore, the degree of freedom in design can be increased by adjusting the shape of the groove.

The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are only schematically shown to the extent that the present invention can be understood and implemented, and the numerical values and the composition (material) of each configuration are shown. It is just an example. Therefore, the present invention is not limited to the described embodiments, and can be changed to various forms as long as it does not deviate from the scope of the technical idea shown in the claims.

The present invention is used as a force sensor that detects an axial force or a load in a machine tool, a pointing device, or the like.

<figref num="1">It is external perspective view of the force sensor which concerns on 1st Embodiment of this invention.</figref><figref num="2">It is a half-cut perspective view which showed the vertical cross section of the force sensor which concerns on 1st Embodiment.</figref><figref num="3">It is external perspective view which shows an example of the chip for a force sensor.</figref><figref num="4">It is a top view of the chip for a force sensor.</figref><figref num="5">It is a half-cut perspective view which showed the vertical cross section of the force sensor which concerns on 2nd Embodiment of this invention.</figref><figref num="6">It is external perspective view of the force sensor which concerns on 3rd Embodiment of this invention.</figref><figref num="7">It is a half-cut perspective view which showed the vertical cross section of the force sensor which concerns on 3rd Embodiment.</figref><figref num="8">It is a half-cut vertical cross-sectional view of the force sensor according to the third embodiment.</figref>

Code description

11 Chip for force sensor 12 Shock absorber 21 Acting part 22 Support part 23A ~ 23D Connecting part 31,32 Groove 100 Force sensor 101 Input part 104 Attenuation mechanism part 200 Force sensor 300 Force sensor 301 Damping mechanism part 304,305 Groove