JP3168179U - Force sensor and six-dimensional force detection device - Google Patents

Abstract

A highly sensitive, compact and robust sensor is provided. A force acting on an object 10 from the object 20 is detected. A detection substrate 100 having an action part 110, a flexible part 120 that supports the action part 110 from the periphery, and a pedestal part 130 that supports the action part 110 is placed on the object 10, and the pedestal part 130 is attached to the object 10 with screws. Fixed. The action part 110 is joined to the force receiving substrate 200 via the raised part 111. The force receiving column 210 extends upward from the upper surface of the force receiving substrate 200, passes through the column insertion hole 310 of the control substrate 300, sticks upward, and the upper end is fixed to the object 20 by the screw S1. The control board 300 is fixed to the pedestal portion 130 by connection elements not shown. When a force + fz or a moment + my is applied from the object 20, the flexible portion 120 is bent, and the resistance value of the piezoresistive element provided on the semiconductor substrate 140 changes. This change in resistance value is detected electrically. [Selection] Figure 18

Description

  The present invention relates to a force sensor and a six-dimensional force detection device, and more particularly to a device that is attached to a robot arm or the like and has a function of detecting an applied force or moment.

  In an industrial robot arm or the like, a detection device that is mounted in the middle of the arm and has a function of detecting an applied force or moment is used. For example, Patent Document 1 below discloses a three-dimensional force detection device that detects a force acting in the three-dimensional coordinate axis directions by detecting a strain generated in a strain generating body using a semiconductor force sensor. ing.

  Further, in Patent Document 2 below, a strain gauge is attached to the side surface of the ring structure, and by detecting the strain generated in the ring structure, a force acting in the direction of each coordinate axis in three dimensions and acting around each coordinate axis A six-dimensional force detection device that detects six components called moments is disclosed. Further, Patent Document 3 below discloses a six-dimensional force detection device that detects the above six components by arranging a plurality of strain gauges on one plane of a disk-like structure.

International Publication No. WO88 / 08522 JP-A-2005-300465 JP 2005-31062 A

  As described above, various types of force sensors attached to industrial robot arms and the like and 6-dimensional force detection devices capable of detecting all six components of force have been developed. However, since these conventional devices are relatively large in size, they are suitable sizes for use on industrial robot arms and humanoid robot wrists / ankles, but they are used as finger joints. Has the problem of being too big.

  In addition, in the type of device that uses a strain gauge for detection, such as the devices disclosed in Patent Documents 2 and 3, the detection unit can be downsized, but the strain gauge has low detection sensitivity. Since an external signal processing circuit is required for signal processing, it is difficult to downsize the overall configuration. On the other hand, it is possible to improve the detection sensitivity by employing a method of electrically detecting the strain generated in the semiconductor substrate by using a semiconductor substrate for the detection unit as in the apparatus disclosed in Patent Document 1 above. However, since the semiconductor substrate is easily damaged by the action of force, there arises a problem that sufficient robustness cannot be secured for use in an industrial robot arm or the like.

  Accordingly, an object of the present invention is to provide a force sensor and a six-dimensional force detection device that can ensure sufficient detection sensitivity and are small and robust.

(1) A first aspect of the present invention has a function of connecting a first object and a second object, and detects a force sensed from the second object with respect to the first object. In the sensor
A detection board connected to the first object, a force receiving board connected to the second object, and a control board for controlling the displacement of the force receiving board;
The detection board is disposed above the first object, the power receiving board is disposed above the detection board, the control board is disposed above the power receiving board, and the second object is disposed above the control board. And
The detection board includes an action portion provided in the center, a flexible portion provided around the action portion, a pedestal portion provided around the flexible portion, and a flexible portion. The upper end of the action part constitutes a raised part raised upward, the flexible part connects the action part and the pedestal part, and the detection part is the flexible part. The force acting on the action part based on the degree of bending is detected as an electrical signal,
The center portion of the lower surface of the force receiving board is fixed to the upper surface of the raised portion, and a force receiving column for connecting to the lower surface of the second object is provided on the upper surface of the force receiving board. A column insertion hole for inserting the column is formed, and the upper end of the force receiving column is inserted through the column insertion hole,
The control board is fixed to the pedestal, and when the second object is displaced relative to the first object, the displacement is transmitted to the force receiving board via the force receiving column, and further to the action part. It is intended to be transmitted.

(2) A second aspect of the present invention is the force sensor according to the first aspect described above,
The control board is fixed to the pedestal portion by a control board fixing screw, and the control board fixing screw is accommodated in a cylindrical spacer. The upper end of the cylindrical spacer is in contact with the lower surface of the control board, and the lower end is the upper surface of the pedestal portion. The control board is formed with a control board fixing screw hole for inserting a control board fixing screw and accommodating and holding the screw head, and a spacer insertion hole for inserting a cylindrical spacer into the force receiving board. Is formed, and a screw receiving hole is formed in the pedestal portion to be screwed with the tip end portion of the control board fixing screw.

(3) A third aspect of the present invention is the force sensor according to the second aspect described above,
The pedestal portion is formed with a pedestal portion fixing screw hole for inserting and holding a pedestal portion fixing screw for fixing the pedestal portion to the first object, and accommodating and holding the screw head. A tool insertion hole for inserting a tool for rotating the head of the base fixing screw from above is formed.

(4) A fourth aspect of the present invention is the force sensor according to the third aspect described above,
A plurality of force receiving pillars are provided at predetermined locations around the force receiving substrate, a plurality of pedestal fixing screws are formed at predetermined locations on the pedestal, and a plurality of predetermined locations around the control substrate are controlled at a plurality of locations. It is fixed by a board fixing screw.

(5) A fifth aspect of the present invention is the force sensor according to the fourth aspect described above,
A center line that passes through the center of the action part and is orthogonal to each substrate is defined, a reference circle centered on the center line is defined on a projection plane that is orthogonal to the center line, and the reference circle is divided into 12 equal parts. A plurality of reference points are defined, and each reference point is defined as a first reference point to a twelfth reference point in the order along the reference circle. , 7, 10 as the B group and the second, 5, 8, 11 reference points as the C group,
Four force receiving columns are arranged at the reference point position of the A group, four sets of base fixing screw holes are arranged at the reference point position of the B group, and four control board fixing screws are located at the reference point position of the C group. It is made to arrange in.

(6) A sixth aspect of the present invention is the force sensor according to the third to fifth aspects described above,
A screw receiving hole is formed at the upper end of the force receiving column to be screwed with the tip of the force receiving substrate fixing screw whose head is fixed to the second object. Protruding upward from the top surface of
The control board fixing screw hole is formed in the upper part of the main body part insertion hole, and the main body part insertion hole having a diameter that can be inserted through the main body part of the control board fixing screw but not through the head part. A head accommodation hole having a diameter necessary to accommodate the head of the control board fixing screw, and
The pedestal part fixing screw hole is formed in the upper part of the main body part insertion hole with a main body part insertion hole having a diameter that can be inserted through the main body part of the pedestal part fixing screw but cannot be inserted through the head part, And a head receiving hole having a diameter necessary for receiving the head of the pedestal fixing screw.

(7) A seventh aspect of the present invention is the force sensor according to the third to sixth aspects described above,
A predetermined upper gap is secured between the periphery of the upper surface of the force receiving board and the periphery of the lower surface of the control board, and a predetermined lower gap is provided between the periphery of the lower surface of the force receiving board and the upper surface of the pedestal portion. As long as the displacement of the force receiving substrate is limited within the range of the upper gap and the lower gap, and the dimensions of the upper gap and the lower gap are subject to displacement under the restriction, The flexible part and the detection part are set in a range where no mechanical damage occurs.

(8) An eighth aspect of the present invention is the force sensor according to the seventh aspect described above,
The cylindrical spacer has a structure in which a main cylindrical member and two sets of sub cylindrical members are stacked. The main cylindrical member has the same thickness as the force receiving substrate, and the auxiliary cylindrical member is a raised portion of the detection substrate. And the thickness of the sub-cylindrical member matches the dimensions of the upper gap and the lower gap.

(9) A ninth aspect of the present invention is the force sensor according to the first to eighth aspects described above,
A predetermined cylindrical gap is secured between the outer peripheral surface of the force receiving column and the inner peripheral surface of the column insertion hole, and the displacement of the force receiving column is limited within the range of the cylindrical gap. And as long as the dimension of a cylindrical space | gap produces the displacement under the said restriction | limiting, it is set as the range which does not produce a mechanical damage to a flexible part and a detection part.

(10) A tenth aspect of the present invention is the force sensor according to the second to eighth aspects described above,
A predetermined cylindrical gap is secured between the outer peripheral surface of the cylindrical spacer and the inner peripheral surface of the spacer insertion hole, and the displacement of the force receiving substrate is limited within the range of the cylindrical gap. And as long as the dimension of a cylindrical space | gap produces the displacement under the said restriction | limiting, it is set as the range which does not produce a mechanical damage to a flexible part and a detection part.

(11) The eleventh aspect of the present invention is the force sensor according to the first to tenth aspects described above,
The flexible part is arranged so as to surround the periphery of the action part, and is constituted by an annular thin part having a thickness that exhibits flexibility,
The detection part acts on the action part based on a semiconductor substrate which is joined to the annular thin part and bends together with the annular thin part, a piezoresistive element formed in the semiconductor substrate, and a resistance value of the piezoresistive element And a circuit that outputs the generated force as an electrical signal.

(12) The twelfth aspect of the present invention is the force sensor according to the first to eleventh aspects described above,
An origin O is defined on a center line that passes through the center of the action part and is orthogonal to each substrate, and an xyz three-dimensional orthogonal coordinate system is defined in which the center line is the z axis and the two axes that are orthogonal to the center line are the x axis and the y axis. sometimes,
The detection unit has a function of detecting a moment mx about the x-axis, a moment my about the y-axis, and a force fz in the z-axis direction acting on the action unit.

(13) A thirteenth aspect of the present invention includes a plurality of sets of force sensors according to the twelfth aspect described above, an arithmetic circuit that performs a calculation based on detection values output from the plurality of sets of force sensors, Constitutes a 6-dimensional force detection device,
In an XYZ three-dimensional orthogonal coordinate system having an origin Q, a force Fx in the X-axis direction, a force Fy in the Y-axis direction, a force Fz in the Z-axis direction, and a force around the X-axis acting on the first object from the second object A function to detect six components of moment Mx, moment My around the Y axis, and moment Mz around the Z axis,
Each pedestal portion of the plurality of sets of force sensors is fixed to the first object at a predetermined position in the XYZ three-dimensional orthogonal coordinate system, and each force receiving column of the plurality of sets of force sensors is XYZ three-dimensional orthogonal Each being fixed to a second object at a predetermined position in the coordinate system;
The arithmetic circuit is configured to perform an operation for obtaining six component values based on the detection values mx, my, and fz detected by the force sensors.

(14) According to a fourteenth aspect of the present invention, in the six-dimensional force detection device according to the thirteenth aspect described above,
A first force sensor having an origin O arranged on the positive X axis of the XYZ three-dimensional orthogonal coordinate system; a second force sensor having an origin O arranged on the negative X axis; A third force sensor having an origin O arranged on an axis and a fourth force sensor having an origin O arranged on a negative Y axis, and the x-axis, y of each force sensor The axis and the z axis are arranged so as to be parallel to the X axis, the Y axis, and the Z axis of the XYZ three-dimensional orthogonal coordinate system, respectively.
The arithmetic circuit sets the moment about the x axis detected by the first force sensor to mx1, the moment about the y axis to my1, the force in the z axis direction to fz1, and the x detected by the second force sensor. Moment about the axis is mx2, moment about the y axis is my2, force in the z axis direction is fz2, moment about the x axis detected by the third force sensor is mx3, moment about the y axis is my3, When the force in the z-axis direction is fz3, the moment around the x-axis detected by the fourth force sensor is mx4, the moment around the y-axis is my4, and the force in the z-axis direction is fz4,
Fx = my1 + my2 + my3 + my4 or = my1 + my2 or = my3 + my4
Fy = mx1 + mx2 + mx3 + mx4 or = mx1 + mx2 or = mx3 + mx4
Fz = fz1 + fz2 + fz3 + fz4 or = fz1 + fz2 or = fz3 + fz4
Mx = fz3-fz4
My = fz2-fz1
Mz = -mx1 + mx2-my3 + my4 or = -mx1 + mx2 or = -my3 + my4
The values of the six components are obtained by the following calculation.

  The force sensor according to the present invention has a simple structure in which a three-layer substrate including a detection substrate, a force receiving substrate, and a control substrate is fixed by screws, so that sufficient robustness can be ensured while being small. In addition, since the displacement of the force receiving substrate can be limited to a certain range by the control substrate, even if an excessive force is applied, the deflection generated in the detecting portion can be suppressed to a certain range, and the semiconductor substrate is placed on the detecting portion. Even if a highly sensitive detection system such as the above is used, the detection system can be prevented from being damaged. Thus, according to the present invention, it is possible to realize a small and robust force sensor with sufficient detection sensitivity. Furthermore, by using a plurality of sets of force sensors, a small and robust system capable of detecting six components, ie, a force acting in the three-dimensional coordinate axis direction and a moment acting around each coordinate axis with sufficient sensitivity. A six-dimensional force detection device can be realized.

FIG. 3 is a side view of a force sensor 500 according to a basic embodiment of the present invention (a control board fixing screw S3 and a cylindrical spacer 250 connecting the detection board 100 and the control board 300 are not shown). It is the upper side figure of the detection board 100 of the force sensor shown in FIG. 1, and the sectional side view in an AA 'cut surface. It is a sectional side view in the BB 'cut surface of the detection board | substrate 100 shown in FIG. It is a sectional side view in the CC 'cut surface of the detection board | substrate 100 shown in FIG. It is the upper side figure of the force receiving board 200 of the force sensor shown in FIG. 1, and the sectional side view in an AA 'cut surface. It is a sectional side view in the BB 'cut surface of the force receiving board | substrate 200 shown in FIG. FIG. 6 is a side sectional view of the force receiving board 200 shown in FIG. It is the upper side figure of the control board 300 of the force sensor shown in FIG. 1, and the sectional side view in an AA 'cut surface. It is a sectional side view in the BB 'cut surface of the control board 300 shown in FIG. It is a sectional side view in the CC 'cut surface of the control board 300 shown in FIG. FIG. 2 is a side cross-sectional view taken along the line AA ′ of the force sensor 500 shown in FIG. 1 (the control board fixing screw S3 and the cylindrical spacer 250 connecting the detection board 100 and the control board 300 are not shown). 11 is a side cross-sectional view of the force sensor 500 shown in FIG. 11 taken along the line AA ′ showing a state where the force receiving substrate 200 is fixed to the second object 20 by the force receiving substrate fixing screw S1 (with the detection substrate 100 and The control board fixing screw S3 and the cylindrical spacer 250 that connect the control board 300 are not shown). FIG. 2 is a side sectional view of the force sensor 500 shown in FIG. 1 taken along the line BB ′ (the control board fixing screw S3 and the cylindrical spacer 250 connecting the detection board 100 and the control board 300 are not shown). In the force sensor 500 shown in FIG. 13, it is a sectional side view taken along the line BB ′ showing a state in which the pedestal portion 130 is fixed to the first object 10 by the pedestal portion fixing screw S2 (detection board 100 and control board). The control board fixing screw S3 and the cylindrical spacer 250 for connecting between them are not shown. FIG. 2 is a side sectional view of the force sensor 500 shown in FIG. 1 taken along the line C-C ′ (showing a state where a cylindrical spacer 250 and a control board fixing screw S3 are removed). 16 is a side cross-sectional view taken along the line CC ′ showing a state in which the control board 300 is fixed to the pedestal portion 130 by the control board fixing screw S3 in the force sensor 500 shown in FIG. It is a top view of the force sensor 500 shown in FIG. FIG. 2 is a side cross-sectional view taken along the line AA ′ for explaining a state in which a moment or force is applied to the force sensor 500 shown in FIG. 1 (fixing of a control board connecting the detection board 100 and the control board 300) The screw S3 and the cylindrical spacer 250 are not shown). It is a bottom view of the semiconductor substrate 140 in the force sensor 500 shown in FIG. 19 is a table showing expansion and contraction states of the piezoresistive elements when moments mx, my and force fz are applied to the force sensor 500 shown in FIG. It is a circuit diagram which shows the electric circuit which outputs the detected value of moment mx, my and force fz based on the table | surface shown in FIG. FIG. 18 is a top view of a six-dimensional force detection device configured by using four sets of force sensors 500 shown in FIG. 17. It is a sectional side view of the 6-dimensional force detection apparatus shown in FIG. It is a top view which shows arrangement | positioning of each force sensor 501-504 in the 6-dimensional force detection apparatus shown in FIG. It is a formula which shows the calculation content which the arithmetic circuit used for the 6-dimensional force detection apparatus shown in FIG. 22 performs. It is a top view which shows the 1st variation of the 6-dimensional force detection apparatus shown in FIG. It is a top view which shows the 2nd variation of the 6-dimensional force detection apparatus shown in FIG. FIG. 16 is a side cross-sectional view illustrating a configuration example of a cylindrical spacer 250 in the force sensor 500 illustrated in FIG. 15. FIG. 12 is a side sectional view showing a detection substrate 100 ′ used in a first modification of the force sensor 500 shown in FIG. FIG. 30 is a bottom view of the detection substrate 100 ′ shown in FIG. 29 (showing a state in which the cover plate 150 ′ is removed; hatching is for showing the region E1, and does not show a cross section). FIG. 12 is a side sectional view showing a detection substrate 100 ″ used in a second modification of the force sensor 500 shown in FIG. 11. FIG. 32 is a bottom view of the detection substrate 100 ″ shown in FIG. 31 (showing a state in which a cover plate 150 ″ is removed. The hatching is for showing the regions E2 and G3, and does not show a cross section).

  Hereinafter, the present invention will be described based on the illustrated embodiment.

<<< §1. Structure of each part of force sensor >>>
FIG. 1 is a side view of a force sensor 500 according to a basic embodiment of the present invention. The force sensor 500 has a function of connecting the first object 10 and the second object 20 (indicated by a broken line in the figure), and acts on the first object 10 from the second object 20. It works to detect force. As shown in the figure, the main components of the force sensor 500 are three substrates: a detection substrate 100, a force receiving substrate 200, and a control substrate 300. Any of the substrates can be made of a metal material such as stainless steel having sufficient robustness in practical use. However, when a silicon substrate is used as the detection unit as in the example described later, the body portion of the detection substrate 100 is made of Kovar or 4-2 alloy in order to ensure consistency of thermal expansion coefficients and improve temperature characteristics. It is desirable to configure using, for example.

  Here, the detection substrate 100 is fixed to the first object 10, and the force receiving substrate 200 is fixed to the second object 20 via the force receiving column 210. In FIG. 1, another force receiving column 210 is arranged in the back of the force receiving column 210 drawn in the center, and the force receiving substrate 200 is connected to the second force receiving column 210 by the second force receiving column 210. It is fixed to the object 20. As will be described later, the control board 300 is formed with column insertion holes for inserting the force receiving columns 210, and the four force receiving columns 210 pass through the column insertion holes. And the second object 20 are connected.

  On the other hand, the detection substrate 100 is bonded to the lower surface of the force receiving substrate 200 via the central raised portion 111. Eventually, the second object 20 is joined above the first object 10 via the force sensor 500. When the second object 20 is displaced, the displacement is transmitted to the force receiving substrate 200 via the four force receiving columns 210 and further to the detection substrate 100 via the raised portion 111. As will be described later, the detection substrate 100 is electrically detected.

  In FIG. 1, a part of the illustration is omitted in order to prevent the figure from becoming complicated, but actually, as will be described in detail later, between the detection board 100 and the control board 300, There are connecting elements (screws and cylindrical spacers) connecting the two, and the control board 300 is fixed to the detection board 100. The control board 300 is not a component directly related to the principle of force detection, but functions to control the displacement of the force receiving board 200. That is, since the control board 300 is fixed to the detection board 100 at a predetermined position above the detection board 100, the displacement of the force receiving board 200 is within the space between the detection board 100 and the control board 300. To be suppressed.

  Hereinafter, detailed structures of the detection substrate 100, the force receiving substrate 200, and the control substrate 300, which are main components of the force sensor 500, will be described in order.

  First, the structure of the detection substrate 100 will be described. The upper part of FIG. 2 is a top view of the detection substrate 100 of the force sensor 500 shown in FIG. 1, and the lower part is a side sectional view taken along the line AA ′. As shown in the upper drawing, the detection substrate 100 is a disc-shaped substrate, and an annular groove G1 is dug on the upper surface. Here, the cylindrical part surrounded by the annular groove G1 is called an action part 110 (the upper end is a raised part 111), the bottom part of the annular groove G1 is called a flexible part 120, and is located on the outer periphery of the annular groove G1. The part to be called will be referred to as a pedestal part 130.

  As shown in the figure, the pedestal portion 130 is provided with pedestal portion fixing screw holes 160 (double circles in the figure) at four locations (positions of 1 o'clock, 4 o'clock, 7 o'clock and 10 o'clock on the dial of the watch) Screw receiving holes 170 (small circles in the figure) are provided at four other positions (positions at 2 o'clock, 5 o'clock, 8 o'clock, and 11 o'clock on the dial of the watch). The pedestal portion fixing screw hole 160 is a screw hole for passing a pedestal portion fixing screw for fixing the pedestal portion 130 to the first object 10, and the screw receiving hole 170 fixes the control board 300 to the pedestal portion 130. It is a screw receiving hole for screwing with the front-end | tip part of the control board fixing screw for doing.

  As shown in the lower diagram of FIG. 2, a cylindrical cavity V is provided on the bottom surface side of the detection substrate 100 (a position below the action part 110 and the flexible part 120). A disk-shaped semiconductor substrate 140 is accommodated. The cavity V is sealed with a lid plate 150. Eventually, the flexible part 120 forms an annular thin part (washer-like structure) in which the annular groove G1 is formed in the upper part and the cavity part V is formed in the lower part, and functions as a diaphragm that is bent by the action of force. Further, the disk-shaped semiconductor substrate 140 is a thin silicon substrate bonded to the lower surfaces of the action part 110 and the flexible part 120, and bends together with the flexible part 120.

  The upper end of the action part 110 constitutes a raised part 111 raised upward. In this embodiment, only the raised portion 111 is prepared as a separate structure and joined to the center of the upper surface of the detection substrate 100. However, the entire action portion 110 including the raised portion 111 is formed as an integrated structure. It doesn't matter. As shown in FIG. 1, the upper surface of the raised portion 111 is joined to the central portion of the force receiving substrate 200.

  FIG. 3 is a sectional side view of the detection substrate 100 shown in FIG. The basic configuration is substantially the same as the lower diagram of FIG. 2 (side sectional view taken along the line AA ′), but the pedestal portion 130 shows a cross section of the pedestal portion fixing screw hole 160. The pedestal portion fixing screw hole 160 is constituted by a main body portion insertion hole 161 provided below and a head receiving hole 162 having a large diameter provided above, and is used for inserting the pedestal portion fixing screw. Is done.

  On the other hand, FIG. 4 is a sectional side view of the detection substrate 100 shown in FIG. The basic configuration is substantially the same as the lower diagram of FIG. 2 (side sectional view taken along the line AA ′), but the pedestal portion 130 shows a cross section of the screw receiving hole 170. As described above, the screw receiving hole 170 is a screw receiving hole for screwing with a tip portion of a control board fixing screw for fixing the control board 300 to the pedestal portion 130.

  Next, the structure of the force receiving substrate 200 will be described. The upper part of FIG. 5 is a top view of the force receiving substrate 200 of the force sensor shown in FIG. 1, and the lower part is a side sectional view taken along the line AA ′. As shown in the upper diagram, the power receiving board 200 is a disk-shaped board, and four power receiving powers are provided at four positions on the upper surface (positions of 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock on the timepiece dial). A pillar 210 is provided. In addition, tool insertion holes 220 are provided at four places (positions at 1 o'clock, 4 o'clock, 7 o'clock and 10 o'clock on the dial of the watch), and at 4 places (2 o'clock, 5 o'clock, 8 o'clock on the dial of the watch). Spacer insertion hole 230 is provided at the position of 11:00. Here, the force receiving column 210 is a component for connecting to the second object, and the tool insertion hole 220 is a tool for rotating the head of the base fixing screw from above, as will be described later. The spacer insertion hole 230 is a hole for inserting a cylindrical spacer, as will be described later.

  As shown in the lower diagram of FIG. 5, the force receiving column 210 is a cylindrical structure that extends upward from the vicinity of the periphery of the force receiving substrate 200, and a screw receiving hole 215 is formed on the upper surface thereof. . The screw receiving hole 215 is a screw receiving hole for screwing with a tip portion of a force receiving board fixing screw for fixing the second object disposed above to the force receiving board 200.

  FIG. 6 is a side sectional view of the force receiving substrate 200 shown in FIG. The basic configuration is substantially the same as the lower diagram of FIG. 5 (side sectional view taken along the line AA ′), but a section of the tool insertion hole 220 is shown. On the other hand, FIG. 7 is a sectional side view of the force receiving board 200 shown in FIG. The basic configuration is substantially the same as the lower part of FIG. 5 (side sectional view taken along the line AA ′), but a cross section of the spacer insertion hole 230 is shown.

  Next, the structure of the control board 300 will be described. The upper part of FIG. 8 is a top view of the control board 300 of the force sensor shown in FIG. 1, and the lower part is a side sectional view taken along the line AA ′. As shown in the upper diagram, the control board 300 is a disk-like board, and column insertion holes 310 are provided at four positions on the upper surface (positions of 3 o'clock, 6 o'clock, 9 o'clock and 12 o'clock on the timepiece dial). , Tool insertion holes 320 are provided at four different locations (1 o'clock, 4 o'clock, 7 o'clock and 10 o'clock on the dial of the watch), and at 4 different locations (2 o'clock and 5 o'clock on the dial of the watch) , 8 o'clock, 11 o'clock positions), control board fixing screw holes 330 are provided. Here, the column insertion hole 310 is a hole for inserting the force receiving column 210, and the tool insertion hole 320 is a hole for inserting a tool for rotating the head of the base fixing screw from above. The control board fixing screw hole 330 is a hole for inserting the control board fixing screw.

  As shown in the lower drawing of FIG. 8, a column insertion hole 310 is provided at the position of the AA ′ cut surface. On the other hand, FIG. 9 is a side sectional view of the control board 300 taken along the line BB ′ shown in FIG. The basic configuration is substantially the same as the lower diagram of FIG. 8 (side sectional view taken along the line AA ′), but a section of the tool insertion hole 320 is shown. FIG. 10 is a side cross-sectional view taken along the line CC ′ of the control board 300 shown in FIG. The basic configuration is substantially the same as the lower diagram of FIG. 8 (side sectional view taken along the line AA ′), but a cross section of the control board fixing screw hole 330 is shown. The control board fixing screw hole 330 is configured by a main body insertion hole 331 provided below and a head receiving hole 332 having a large diameter provided above, and is used for inserting the control board fixing screw. Is done.

<<< §2. Overall structure of force sensor >>
Next, the overall structure of the force sensor 500 shown in FIG. 1 will be described with reference to side sectional views taken along three different cut surfaces.

  11 is a side sectional view taken along the line AA ′ of the force sensor 500 shown in FIG. 1, and the force receiving board 200 shown in the lower part of FIG. 5 is arranged above the detection board 100 shown in the lower part of FIG. 8 shows a state in which the control board 300 shown in the lower part of FIG. 8 is arranged above (the control board fixing screw and the cylindrical spacer for connecting the detection board 100 and the control board 300 are not shown in the figure). The same applies to 12). Here, the individual components of each substrate are as described above.

  As shown in the figure, the force receiving column 210 extending upward from the force receiving substrate 200 passes through a column insertion hole 310 provided in the control substrate 300, and its upper end protrudes upward from the upper surface of the control substrate 300. ing. A screw receiving hole 215 is formed at the upper end of the force receiving column 210, and the upper end of the force receiving column 210 can be fixed to the second object 20 by using the screw receiving hole 215.

  FIG. 12 shows a side of the force sensor 500 shown in FIG. 11 on the AA ′ cut surface showing a state where the force receiving substrate 200 is fixed to the second object 20 (indicated by a broken line) by the force receiving substrate fixing screw S1. It is sectional drawing. The force receiving board fixing screw S1 has a head fixed to the second object 20 (the structure on the second object 20 side is not shown), and is a screw receiving hole formed at the upper end of the force receiving column 210. Reference numeral 215 denotes a structure that is screwed with the tip of the force receiving substrate fixing screw S1. Therefore, if a structure for fixing the heads of the four force receiving board fixing screws S1 is provided on the second object 20 side, the four screws S1 are used to fix the second object to the four force receiving forces. The second object 20 can be fixed to the pillar 210 and is connected to the force receiving substrate 200 via the force receiving pillar 210.

  As shown in the figure, a predetermined cylindrical gap is secured between the outer peripheral surface of the cylindrical force receiving column 210 and the inner peripheral surface of the column insertion hole 310, and the degree of freedom given by this cylindrical gap. Within the range, the force receiving column 210 can be freely displaced. For this reason, the displacement of the second object 20 is transmitted to the force receiving substrate 200 via the force receiving column 210.

  FIG. 13 is a side sectional view of the force sensor 500 shown in FIG. 1 taken along the line BB ′. The force receiving board 200 shown in FIG. 6 is arranged above the detection board 100 shown in FIG. 9 shows a state in which the control board 300 shown in FIG. 9 is disposed above (the control board fixing screw and the cylindrical spacer connecting the detection board 100 and the control board 300 are not shown, and the same applies to FIG. 14). Here, the individual components of each substrate are as described above.

  As shown in the figure, a tool insertion hole 220 provided in the force receiving substrate 200 is disposed directly above the pedestal portion fixing screw hole 160 provided in the pedestal portion 130 of the detection substrate 100, and further, the control substrate is disposed directly above the tool insertion hole 220. A tool insertion hole 320 provided in 300 is disposed.

  FIG. 14 is a sectional side view taken along the line BB ′ showing a state in which the pedestal portion 130 is fixed to the first object 10 (shown by a broken line) with the pedestal portion fixing screw S2 in the force sensor 500 shown in FIG. (The structure on the first object 10 side is not shown).

  FIG. 14 shows a state in which the second object 20 is arranged. Actually, however, the pedestal portion of the force sensor 500 is attached before the second object 20 is attached above the force sensor 500. 130 may be attached to the upper surface of the first object 10. That is, when the second object 20 is not attached, the pedestal fixing screw S2 can be inserted into the pedestal fixing screw hole 160 from above through the tool insertion hole 320 and the tool insertion hole 220. A tool such as a screwdriver can be inserted from above through the tool insertion hole 320 and the tool insertion hole 220, and the head of the base fixing screw S2 can be rotated.

  The pedestal portion fixing screw hole 160 formed in the pedestal portion 130 has a function of inserting and holding the screw head while inserting the pedestal portion fixing screw S2. More specifically, as shown in FIG. 13, the pedestal portion fixing screw hole 160 is inserted into the main body portion with a diameter that allows the main body portion of the pedestal portion fixing screw S2 to be inserted but not the head portion. It has a hole 161 and a head receiving hole 162 formed in the upper part of the main body part insertion hole 161 and having a diameter necessary for receiving the head of the pedestal fixing screw S2. Therefore, as shown in FIG. 14, if a screw receiving hole is formed on the first object 10 to be screwed with the tip of the pedestal fixing screw S2, the pedestal 130 is moved by the four screws S2. The detection substrate 100 can be connected to the first object 10.

  FIG. 15 is a side sectional view taken along the line CC ′ of the force sensor 500 shown in FIG. 1. The force receiving board 200 shown in FIG. 7 is arranged above the detection board 100 shown in FIG. The state which has arrange | positioned the control board 300 shown in FIG. 10 above is shown. Here, the individual components of each substrate are as described above. The cylindrical spacer 250 drawn beside the force receiving board 200 is a cylindrical member (which may be made of metal or resin) that can accommodate the control board fixing screw S3. Is used by being disposed in the spacer insertion hole 230.

  The control board 300 is formed with a control board fixing screw hole 330 for inserting the control board fixing screw S3 and accommodating and holding the screw head. The control board fixing screw hole 330 includes a main body part insertion hole 331 having a diameter through which the main body part of the control board fixing screw S3 can be inserted but the head part cannot be inserted, and the main body part insertion hole 331. And a head receiving hole 332 having a diameter necessary to receive the head of the control board fixing screw S3.

  FIG. 16 is a cross-sectional side view taken along the line CC ′ showing a state in which the control board 300 is fixed to the pedestal portion 130 with the control board fixing screw S3 in the force sensor 500 shown in FIG. As illustrated, the control board fixing screw S <b> 3 is accommodated in a cylindrical spacer 250, and the cylindrical spacer 250 is inserted through a spacer insertion hole 230 formed in the force receiving board 200. In addition, a screw receiving hole 170 is formed in the pedestal portion 130 so as to be screwed with the tip end portion of the control board fixing screw S3. Therefore, when the control board fixing screw S3 is tightened, the upper end of the cylindrical spacer 250 is in contact with the lower surface of the control board 300, and the lower end is in contact with the upper surface of the pedestal portion 130. Thus, the control board 300 is fixed to the pedestal portion 130 by the control board fixing screw S3.

  FIG. 16 shows a state in which the second object 20 is arranged, but actually, before the second object 20 is mounted above the force sensor 500, a control board of the force sensor 500 is shown. 300 may be attached to the upper surface of the pedestal portion 130. That is, in a state where the second object 20 is not attached, the cylindrical spacer 250 is inserted into the spacer insertion hole 230 formed in the force receiving substrate 200, and the control substrate 300 is mounted thereon, and the four control substrates. The fixing screw S3 may be fastened and fixed.

  FIG. 17 is a top view of the force sensor 500 shown in FIG. In the drawing, only the control board 300 arranged in the uppermost layer appears, but the force receiving board 200 and the detection board 100 are arranged under this. As described with reference to FIG. 8, a total of 12 holes are formed on the control board 300.

  A column insertion hole 310 is formed at the 0, 3, 6, and 9 o'clock position of the dial of the watch, and the force receiving column 210 attached to the upper surface of the force receiving substrate 200 is inserted upward. is doing. A screw receiving hole 215 is formed on the upper surface of the force receiving column 210, and as described above, the tip end portion of the force receiving substrate fixing screw S1 for connecting the second object 20 is screwed together.

  In addition, a tool insertion hole 320 is formed at 1 o'clock, 4 o'clock, 7 o'clock, and 10 o'clock on the dial of the watch, and when viewed from above, the head of the pedestal fixing screw S2 can be seen. . As described above, a tool such as a screwdriver can be inserted from the tool insertion hole 320 to rotate the head of the pedestal fixing screw S2 and fix the pedestal 130 to the first object 10. On the other hand, control board fixing screw holes 330 are formed at the 2 o'clock, 5 o'clock, 8 o'clock, and 11 o'clock positions on the timepiece dial, and a control board fixing screw S3 is inserted into the control board fixing screw S3. Is fixed to the pedestal 130.

  After all, in the case of the force sensor 500 shown here, a center line that passes through the center of the action unit 110 and is orthogonal to the substrates 100, 200, and 300 is defined, and a projection plane orthogonal to the center line (for example, shown in FIG. 17). When a reference circle U (indicated by a broken line in FIG. 17) having the center line T as the center point T is defined on the upper surface of the control board 300, the centers of 12 holes (reference lines) formed on the control board 300 are defined. Each point) is located on the reference circle U. Then, a total of twelve reference points are defined at positions that equally divide the reference circle U into twelve, and each reference point is arranged in the order along the reference circle in the same manner as the order of the numbers on the dial of the watch. Points to the 12th reference point, the 3rd, 6th, 9th and 12th reference points are the A group, the 1st, 4th, 7th and 10th reference points are the B group, and the 2nd, 5th, 8th and 11th reference points Is a group C, the four force receiving columns 210 are arranged at the respective reference point positions of the group A, and the four sets of base part fixing screw holes 160 (and tool insertion holes for rotating the base part fixing screws S2). 220, 320) are arranged at the reference point position of the B group, and the four control board fixing screws S3 are arranged at the reference point position of the C group.

  Of course, the number of force receiving columns 210, the number of pedestal portion fixing screw holes 160, and the number of control board fixing screws S3 do not necessarily have to be four sets. It is possible to configure a force sensor according to the present invention. However, for practical use, it is preferable to use a plurality of sets, respectively, and it is preferable to arrange them at the periphery of each substrate. That is, practically, a plurality of force receiving pillars 210 are provided at predetermined locations around the force receiving substrate 200, and a plurality of pedestal fixing screws 160 are formed at predetermined locations on the pedestal 130, It is preferable to fix the predetermined part of the part to the pedestal part 130 with a plurality of control board fixing screws S3.

  In the embodiment shown here, each of the substrates 100, 200, and 300 is a disk-shaped substrate, but the shape of each substrate is not necessarily limited to a circle, and may be any shape such as a rectangle or a hexagon. Alternatively, the shape may be different for each substrate.

<<< §3. Force sensor detection operation >>>
Next, the detection operation by the force sensor 500 shown in FIG. 1 will be described. FIG. 18 is a sectional side view taken along the line AA ′ for explaining a state in which a moment or force is applied to the force sensor 500 (a control board connecting the detection board 100 and the control board 300). The fixing screw S3 and the cylindrical spacer 250 are not shown).

  As described above, the force sensor 500 is mounted between the first object 10 and the second object 20 indicated by broken lines in the drawing, and has a function of connecting the two objects to each other. As illustrated, the detection substrate 100 is disposed above the first object 10, the force receiving substrate 200 is disposed above the detection substrate 100, the control substrate 300 is disposed above the force receiving substrate 200, and the second The object 20 is disposed above the control board 300. Of course, the upper and lower positional relationship referred to here is a convenience for explaining the relative arrangement of each component, and in practice, the force sensor 500 may be mounted in any orientation. It doesn't matter.

  In this application, the function of the force sensor 500 will be described as “a function for detecting the force acting on the first object 10 from the second object 20”. The force acting between the objects is reciprocal, and the force sensor 500 naturally has a “function for detecting the force acting on the second object 20 from the first object 10”. Yes.

  The basic structure of the force sensor 500 is as follows. That is, in FIG. 18, the pedestal portion 130 is fixed to the first object 10, and the control board 300 is fixed to the pedestal portion 130 by screws S3 and a cylindrical spacer 250 (not shown in FIG. 18). Therefore, the base part 130 and the control board 300 are fixed to the first object 10. On the other hand, the center part of the lower surface of the force receiving substrate 200 is fixed to the upper surface of the raised portion 111, and four force receiving columns 210 for connecting to the lower surface of the second object 20 are formed on the upper surface of the force receiving substrate 200. Is provided. The control board 300 is formed with column insertion holes 310 through which the force receiving columns 210 are inserted. The upper ends of the force receiving columns 210 are inserted through the column insertion holes 310 and protrude upward. The second object 20 is fixed.

  Further, the detection substrate 100 is provided at the center of the action portion 110 provided at the center, the flexible portion 120 provided around the action portion 110 and having flexibility, and provided around the flexible portion 120. And the upper end of the action part 110 constitutes a raised part 111 raised upward, and the flexible part 120 is a flexible connecting member that connects the action part 110 and the base part 130. It functions as a (thin diaphragm). Note that the flexible portion 120 is not necessarily configured by a diaphragm, and may be configured by a plurality of beam structures. In this case, the action part 110 is supported by a plurality of beam structures from the periphery.

  In the force sensor 500 having such a basic structure, when a force acts on the second object 20 with the first object 10 fixed, the force acts from the force receiving column 210 through the force receiving substrate 200. Is transmitted to the unit 110. Then, the flexible part 120 that connects the action part 110 and the pedestal part 130 is bent by the action of the transmitted force. As described above, since the flexible portion 120 is bent, the second object 20 is displaced with respect to the first object 10 and the pedestal portion 130 together with the force receiving substrate 200 and the action portion 110. In other words, when the second object 20 is displaced with respect to the first object 10, the displacement is transmitted to the force receiving substrate 200 via the force receiving column 210 and further to the action unit 110, so that the flexible portion 120 will bend.

  The detection substrate 100 is further provided with a detection unit that detects the bending of the flexible unit 120. In the case of the illustrated embodiment, the semiconductor substrate 140 functions as this detection unit and functions to detect a force acting on the action unit 110 as an electric signal based on the degree of bending of the flexible part 120.

  FIG. 19 is a bottom view of the semiconductor substrate 140 in the force sensor 500 shown in FIG. The semiconductor substrate 140 is a disk-shaped silicon substrate, and a total of 12 sets of piezoresistive elements R are formed on the lower surface thereof. A detection circuit (not shown) is connected to these piezoresistive elements R. As already described, the flexible part 120 is arranged so as to surround the action part 110, and is constituted by an annular (washer-like) thin part having a thickness that exhibits flexibility, and the semiconductor substrate 140. The outer periphery of this corresponds to the outer periphery of the annular flexible portion 120. In other words, the outer peripheral portion of the semiconductor substrate 140 is in contact with the inner peripheral surface of the pedestal portion 130.

  After all, in the case of this embodiment, the detection unit is joined to the flexible portion 120 formed of the annular thin portion, and the semiconductor substrate 140 that is bent together with the flexible portion 120, and the 12 sets formed in the semiconductor substrate 140. The piezoresistive element R, and a circuit that outputs, as an electrical signal, a force that acts on the action unit 110 based on a change in the resistance value of the piezoresistive element R.

  Here, for convenience of explanation, as shown in FIG. 18, an origin O is defined on a center line that passes through the center of the action unit 110 and is orthogonal to each substrate, the center line is defined as the z axis, and two axes that are orthogonal to the center line. Define an xyz three-dimensional orthogonal coordinate system with x as the x-axis and y-axis. In the case of the example in FIG. 18, the origin O is defined at the center of the lower surface of the semiconductor substrate 140, and the x axis is in the right direction in the figure, the z axis is in the downward direction in the figure, and the y axis is in the near direction perpendicular to the drawing sheet. Each is defined. The detection unit has a function of detecting a moment mx around the x axis, a moment my around the y axis, and a force fz in the z axis direction that acted on the action unit 110 (that is, the second object 20).

  In the present application, a force acting in the positive direction of each coordinate axis is defined as a positive force related to the coordinate axis, and a moment acting in the rotation direction in which the right screw is advanced in each coordinate axis direction is treated as a positive moment related to the coordinate axis. 18 represents a positive moment around the y-axis acting on the second object 20, and + fz represents a positive force acting on the second object 20 in the z-axis direction.

  In order to define the physically accurate moments mx and my, it is necessary to accurately define the position of the origin O serving as the center of rotation. However, the exact position of the actual origin O is determined by the flexible portion 120. In addition, since it is determined depending on the thickness and deformation characteristics of the semiconductor substrate 140, it can be determined only when an actual apparatus is designed. Therefore, here, for the sake of convenience, as shown in FIG. 18, a description will be made with the origin O defined at the center point of the lower surface of the semiconductor substrate 140.

  FIG. 19 is a bottom view of the semiconductor substrate 140, in which the x axis is defined in the right direction of the figure and the y axis is defined in the upward direction of the figure. The twelve piezoresistive elements R are all elongated elements formed on the surface of the semiconductor substrate 140 (silicon substrate), and are characterized by their arrangement. That is, four sets of elements Rx1 to Rx4 used for detecting the moment my are arranged along the x axis, and four sets of elements Ry1 to Ry4 used for detecting the moment mx are arranged along the y axis, The four sets of elements Rz1 to Rz4 used for detecting the force fz are arbitrary axes (in the illustrated example, axes arranged parallel to and in the vicinity of the x axis. For example, with respect to the x axis and the y axis, (It may be an inclined axis).

  The elements Rx1, Rx4, Ry1, Ry4, Rz1, Rz4 are arranged in the vicinity of the outer periphery of the annular flexible part 120, and the elements Rx2, Rx3, Ry2, Ry3, Rz2, Rz3 are annular flexible Although these are disposed in the vicinity of the inner peripheral portion of the portion 120, these positions are positions where the largest mechanical stress is generated when the flexible portion 120 is bent. That is, the detection sensitivity can be increased by arranging each element at these positions.

  FIG. 20 is a table showing the expansion / contraction state of each piezoresistive element R when moments + mx, + my and force + fz are applied to the force sensor 500 shown in FIG. “+” In the table indicates that a stress extending in the longitudinal direction acts on the element, “−” indicates that a stress contracting in the longitudinal direction acts on the element, and “0” indicates a stress in the longitudinal direction. Indicates that does not work. For example, when a moment + my acts on the second object 20, a displacement as indicated by an arrow + my in FIG. 18 occurs, and the power receiving board 200 moves downward on the left side of the drawing and moves upward on the right side of the drawing. It will be. As a result, the flexible portion 120 and the semiconductor substrate 140 are bent, and stress that extends in the longitudinal direction (x-axis direction) acts on the elements Rx1 and Rx3, and contraction stress acts on the elements Rx2 and Rx4. The same stress acts on the elements Rz1 to Rz4 in the longitudinal direction, but no stress in the longitudinal direction works on the elements Ry1 to Ry4. The second row of the table in FIG. 20 shows the stretched state at this time. When the counter-rotating moment -my is applied, the expansion / contraction state is reversed.

  Similarly, when a moment + mx acts on the second object 20, a stress that extends in the longitudinal direction (y-axis direction) acts on the elements Ry1 and Ry3, and a contracting stress acts on the elements Ry2 and Ry4. No stress in the longitudinal direction acts on the elements Rx1 to Rx4 and the elements Rz1 to Rz4. The first line of the table in FIG. 20 shows the stretched state at this time. When the counterclockwise moment -mx is applied, the expansion / contraction state is reversed.

  Further, when a force + fz is applied to the second object 20, a displacement as indicated by an arrow + fz in FIG. 18 occurs, and the entire force receiving substrate 200 moves downward in the drawing. As a result, the flexible portion 120 and the semiconductor substrate 140 are bent, and stress that contracts in the longitudinal direction acts on the elements Rz1 and Rz4, and stress that expands acts on the elements Rz2 and Rz3. The same applies to the elements Rx1 to Rx4 and the elements Ry1 to Ry4. The third row of the table in FIG. 20 shows the stretched state at this time. When the reverse force -fz is applied, the expansion / contraction state is reversed.

  Since the piezoresistive element R has a property that the electric resistance value changes according to the expansion / contraction state, if the change of the electric resistance value of each element R can be recognized, the applied moments mx, my and force fz Can be detected as an electrical signal. Therefore, an electric circuit as shown in FIGS. 21 (a), (b) and (c) is prepared. Each of these circuits is a Wheatstone bridge formed by using four sets of elements R. When each element R is a P-type piezoresistive element, a correct detection value including a sign can be obtained. ing.

  The circuit shown in FIG. 21 (a) is a bridge circuit for the elements Rx1 to Rx4. When a predetermined voltage is supplied to the bridge from the power source, the potential difference measured by the potentiometer Vx indicates the moment my around the y axis. (The sign indicates the direction of the moment). This is because the electrical resistance of each element changes according to the moment acting on the second object 20 based on the stretched state shown in the second row of the table of FIG. When only the moment my around the y-axis acts, the outputs from the potentiometers Vy and Vz shown in FIGS. 21 (b) and 21 (c) are 0, and other axis components are not erroneously detected. .

  The circuit shown in FIG. 21 (b) is a bridge circuit for the elements Ry1 to Ry4. When a predetermined voltage is supplied to the bridge from the power source, the potential difference measured by the potentiometer Vy indicates the moment mx around the x axis. (The sign indicates the direction of the moment). This is because the electrical resistance of each element changes according to the moment acting on the second object 20 based on the stretched state shown in the first row of the table of FIG. When only the moment mx around the x-axis acts, the outputs from the potentiometers Vx and Vz shown in FIGS. 21 (a) and 21 (c) are 0, and the other-axis component is also erroneously detected. Absent.

  The circuit shown in FIG. 21 (c) is a bridge circuit for the elements Rz1 to Rz4. When a predetermined voltage is supplied to the bridge from the power supply, the potential difference measured by the potentiometer Vz indicates the force fz in the z-axis direction. (The sign indicates the direction of the force). This is because the electrical resistance of each element changes according to the force acting on the second object 20 based on the stretched state shown in the third row of the table of FIG. Also in this case, when only the force fz in the z-axis direction is applied, the outputs from the potentiometers Vx and Vy shown in FIGS. 21 (a) and 21 (b) are 0, and the other-axis component is erroneously detected. There is nothing.

  Thus, the detection circuit shown in FIG. 21 can detect the moment mx around the x-axis, the moment my around the y-axis, and the force fz in the z-axis acting on the second object 20. Note that such a detection circuit can be formed in the semiconductor substrate 140. As a result, the detection circuit shown in FIG. If a wiring terminal to the outside is prepared at a location, the detection result can be taken out as an electric signal from the wiring terminal.

  As described above, the example in which the detection unit is configured by the semiconductor substrate 140, the piezoresistive element R and the detection circuit formed on the semiconductor substrate 140 has been described, but the detection unit used in the force sensor according to the present invention is as follows. It is not limited to the said Example. In short, as long as it has a function of detecting, as an electrical signal, the force acting on the action part 110 (that is, the second object 20) based on the degree of bending of the flexible part 120, various other forms are possible. It is possible to employ the detection unit.

  The most important feature of the force sensor 500 according to the present invention is that a control board 300 fixed to the pedestal portion 130 is provided, and the displacement of the force receiving board 200 can be controlled by the control board 300. Is a point. In the structure shown in FIG. 18, even if a large force is applied to the second object 20, the downward displacement of the force receiving substrate 200 is controlled by the pedestal portion 130, and the upward displacement is controlled by the control substrate 300. It will be. In other words, the displacement of the force receiving board 200 is limited within a space sandwiched between the pedestal portion 130 and the control board 300.

  This means that the displacement transmitted to the flexible part 120 and the semiconductor substrate 140 is also limited to a predetermined range. Therefore, even when an excessive force is applied to the second object 20, the flexible portion 120 and the semiconductor substrate 140 are not excessively bent. When excessive bending occurs in the flexible part 120, the elastic deformation region is exceeded and plastic deformation occurs. As a result, the zero point of the detection system is displaced, and an accurate detection value cannot be obtained. Further, if the semiconductor substrate 140 is excessively bent, it is mechanically damaged. Even when an excessive load is applied, the control board 300 plays a role of preventing the above-described problem from occurring.

  This protection function is particularly effective when a detection circuit is formed on the semiconductor substrate 140. In general, a detection system using a piezoresistive element can obtain a sensitivity 50 to 100 times that of a detection system using a strain gauge, and practically can be directly captured by an AD converter built in a microcomputer. An electric signal having a sufficient signal level can be obtained. For this reason, when a detection system using a piezoresistive element is used, an amplifier circuit becomes unnecessary, and an advantage of reducing the scale of the signal processing circuit can be obtained. However, such a high-sensitivity detection system is vulnerable to excessive stress. In fact, in the detection system using the semiconductor substrate 140 described above, mechanical damage occurs when excessive stress is applied. End up.

  In the force sensor 500 according to the present invention, since the protection function is added, there is no fear of breakage even if such a high-sensitivity detection system is used. Further, the basic structure of the force sensor 500 is a simple structure composed of three layers of the detection substrate 100, the force receiving substrate 200, and the control substrate 300, and can be fixed with screws. Although it is small, sufficient robustness can be ensured.

  Thus, according to the present invention, sufficient detection sensitivity can be ensured, and a small and robust force sensor can be realized.

<<< §4. Example of 6-dimensional force detection device >>>
As described above, the force sensor 500 described so far has a function of detecting the three components of the moment mx around the x axis, the moment my around the y axis, and the force fz in the z axis acting on the second object 20. have. However, in the industry, there is an increasing demand for six-dimensional force detection devices that detect six components, ie, a force acting in the direction of each three-dimensional coordinate axis and a moment acting around each coordinate axis.

  Here, an embodiment in which a six-dimensional force detection device is configured by using a plurality of force sensors 500 described so far will be described. In §3, an xyz three-dimensional coordinate system (local coordinate system) having an origin O is defined in order to explain the operation of the force sensor 500. However, in this embodiment of the six-dimensional force detection device, the origin Q is used for convenience. An XYZ three-dimensional coordinate system (global coordinate system) having “” is defined, and a description is given by distinguishing both coordinate systems. In the end, the 6-dimensional force detection device described here is an X-axis direction force Fx and a Y-axis direction force acting on the first object from the second object in the XYZ three-dimensional orthogonal coordinate system having the origin Q. The apparatus has a function of detecting six components of Fy, a force Fz in the Z-axis direction, a moment Mx around the X-axis, a moment My around the Y-axis, and a moment Mz around the Z-axis.

  Such a six-dimensional force detection apparatus is configured by a plurality of sets of force sensors 500 described so far, and an arithmetic circuit that performs a calculation based on detection values output from the plurality of sets of force sensors 500. be able to. That is, each pedestal portion 130 of the plurality of force sensors 500 is fixed to the first object at a predetermined position in the XYZ three-dimensional orthogonal coordinate system, and each force receiving column 210 is fixed to the second object. That's fine. Since the detection values mx, my, and fz are obtained from the force sensors 500, a predetermined calculation for obtaining the values of the six components based on the detection values mx, my, and fz by the arithmetic circuit. Should be done.

  FIG. 22 is a top view of a six-dimensional force detection device configured by using four sets of force sensors 500 shown in FIG. The large circle shown in the figure is the upper surface of the first object 30, and four sets of force sensors 500 are arranged thereon. Here, in order to distinguish these four sets, they will be called force sensors 501 to 504, respectively. In the case of the illustrated example, the origin Q is defined on the central axis of the first object 30 (axis orthogonal to the paper surface of FIG. 22), the central axis is the Z axis, the X axis is on the right side of FIG. An XYZ three-dimensional orthogonal coordinate system is defined by taking the Y-axis.

  FIG. 23 is a side cross-sectional view of the 6-dimensional force detection device shown in FIG. 22 cut along the XZ plane, and shows cross sections of two sets of force sensors 501 and 502. A force sensor 504 is disposed in the back, but the illustration is omitted to avoid the figure from becoming complicated. As shown in this sectional side view, the four sets of force sensors 501 to 504 are mounted between the first object 30 (shown by a broken line) and the second object 40 (shown by a broken line). Similarly to the mounting configuration of the force sensor 500 described above, the pedestal 130 is fixed to the first object 30 and the force receiving column 210 is fixed to the second object 40. In FIG. 22, the second object 40 is omitted, but actually, the second object 40 is attached on each of the force sensors 501 to 504. Note that the origin Q of the XYZ three-dimensional orthogonal coordinate system is defined on a plane including each origin O of the xyz three-dimensional orthogonal coordinate system.

  The detection target of this six-dimensional force detection device is a six-component force acting on the first object 30 from the second object 40. FIG. 23 shows the force + Fx, + Fz and the moment + My being white. Illustrated with arrows. The force + Fy is a force toward the front side perpendicular to the paper surface in FIG. 23, and the moment + Mx is a moment for rotating the second object 40 around the X axis. The moment + Mz is a moment for rotating the second object 40 (not shown) clockwise in FIG.

  In this way, the six components Fx, Fy, Fz, Mx, My, and Mz that are detection targets of the six-dimensional force detection device are components defined in the XYZ three-dimensional orthogonal coordinate system having the origin Q to the last. This is slightly different from mx, my, and fz detected by the individual force sensors 501 to 504. However, between the local coordinate system (xyz three-dimensional orthogonal coordinate system) of each of the force sensors 501 to 504 and the global coordinate system (XYZ three-dimensional orthogonal coordinate system) of the six-dimensional force detection device, the coordinate axes respectively If the scientific correspondence is determined, the six components Fx, Fy, Fz, Mx, My, and Mz can be calculated by a predetermined calculation using the detected values mx, my, and fz.

  In the embodiment shown here, the force sensors 501 to 504 are arranged so that the x-axis, y-axis, and z-axis are parallel to the X-axis, Y-axis, and Z-axis of the XYZ three-dimensional orthogonal coordinate system, respectively. Thus, the calculation by the calculation circuit is simplified. 24 is a top view showing the arrangement of the force sensors 501 to 504 in the six-dimensional force detection apparatus shown in FIG. For convenience, each force sensor 501 to 504 is shown only with its outline (circle), the positions of four force receiving columns (indicated by asterisks), the origin O, and the x and y axis directions. In any force sensor, the detection axes x and y are parallel to the X and Y axes of the global coordinate system, and the detection axis z (axis perpendicular to the paper surface) is also parallel to the Z axis of the global coordinate system. It has become.

  The first force sensor 501 is arranged so that the origin O is on the positive X axis, and the second force sensor 502 is arranged so that the origin O is on the negative X axis. The force sensor 503 is arranged so that the origin O is on the positive Y axis, and the fourth force sensor 504 is arranged so that the origin O is on the negative Y axis.

  The symbols in the balloons shown in FIG. 24 indicate the forces and moments detected by the force sensors 501 to 504. That is, here, the moment about the x-axis detected by the first force sensor 501 is mx1, the moment about the y-axis is my1, the force in the z-axis direction is fz1, and is detected by the second force sensor 502. The moment about the x axis is mx2, the moment about the y axis is my2, the force in the z axis direction is fz2, and the moment about the x axis detected by the third force sensor 503 is mx3, about the y axis. The moment is my3, the z-axis direction force is fz3, the moment around the x-axis detected by the fourth force sensor 504 is mx4, the moment around the y-axis is my4, and the z-axis direction force is fz4.

  FIG. 25 is an equation showing the calculation contents executed by the calculation circuit used in the six-dimensional force detection apparatus. That is, on the premise that the detection results as shown in the balloons of FIG. 24 are obtained from the four sets of force sensors 501 to 504, by performing calculations according to the respective arithmetic expressions shown in FIG. 25, Fx, Six components of Fy, Fz, Mx, My, and Mz can be obtained.

Specifically, the force Fx in the X-axis direction is
Fx = my1 + my2 + my3 + my4 or = my1 + my2 or = my3 + my4
The force Fy in the Y-axis direction can be calculated by
Fy = mx1 + mx2 + mx3 + mx4 or = mx1 + mx2 or = mx3 + mx4
The force Fz in the Z-axis direction is
Fz = fz1 + fz2 + fz3 + fz4 or = fz1 + fz2 or = fz3 + fz4
Can be obtained by the following calculation.
Similarly, the moment Mx around the X axis is
Mx = fz3-fz4
The moment My about the Y axis is
My = fz2-fz1
The moment Mz around the Z axis is
Mz = -mx1 + mx2-my3 + my4 or = -mx1 + mx2 or = -my3 + my4
Can be obtained by the following calculation.

  In any case, the sign of the obtained calculation value indicates the direction of the applied force or moment. The reason why the values of these six components can be obtained by the above arithmetic expression is that the four sets of force sensors 501 to 504 adopt the arrangement shown in FIG. That is, these arithmetic expressions are obtained by the force receiving columns of the force sensors 501 to 504 (indicated by an asterisk in the figure) when the force or moment of each component is applied from the second object 40 in the arrangement shown in FIG. It can be theoretically derived by examining what force acts on the position shown.

  Of course, the arrangement of the force sensor shown in FIG. 24 shows an example, and the 6-dimensional force detection apparatus according to the present invention is not limited to an apparatus adopting such an arrangement. For example, FIG. 26 is a top view showing a first variation of the six-dimensional force detection device according to the present invention. In the example shown in FIG. 24, four sets of force sensors 501 to 504 are arranged on the X axis or Y axis, but in the variation shown in FIG. 26, the four sets of force sensors 511 to 514 are respectively XY. Arranged in the first to fourth quadrants of the coordinates. The same is true in that the coordinate axes x, y, and z of the local coordinate system are arranged in parallel to the coordinate axes X, Y, and Z of the global coordinate system.

  On the other hand, FIG. 27 is a top view showing a second variation of the six-dimensional force detection device according to the present invention. In the example shown in FIG. 24, four sets of force sensors 501 to 504 are used, but in the variation shown in FIG. 27, only three sets of force sensors 521 to 523 are used. The first force sensor 521 is disposed on the negative Y axis, the second force sensor 522 is disposed in the third quadrant of the XY coordinates, and the third force sensor 523 is disposed in the fourth quadrant of the XY coordinates. Is arranged. More specifically, the second force sensor 522 and the third force sensor 523 are both arranged at a position where the line connecting the points QO forms 60 ° with respect to the Y axis.

  In the variations shown in FIG. 26 and FIG. 27, the arithmetic expression executed by the arithmetic circuit is different from that shown in FIG. 25, but Fx, Fy, Fz, Mx, Six components of My and Mz can be obtained.

<<< §5. Other Examples >>>
Finally, some modifications of the force sensor according to the present invention will be described. Of course, by using a plurality of sets of these modified examples, the 6-dimensional force detection device described in Section 4 can be configured.

(1) Structure of the cylindrical spacer 250 As described in the embodiment shown in FIG. 18, in the force sensor 500 according to the present invention, between the upper surface periphery of the force receiving substrate 200 and the lower surface periphery of the control substrate 300. A predetermined upper gap is secured, and a predetermined lower gap is secured between the periphery of the lower surface of the force receiving substrate 200 and the upper surface of the pedestal portion 130. The displacement of the force receiving substrate 200 It is comprised so that it may restrict | limit within the range of a downward space | gap. As a result, even when an excessive force is applied to the second object 20, it is possible to prevent the flexible portion 120 and the semiconductor substrate 140 (detection portion) from being excessively bent.

  Therefore, when designing the force sensor 500, the upper gap and the lower gap are within a range in which the flexible portion 120 and the detection portion are not mechanically damaged as long as the displacement under the restriction of the gap occurs. Must be set to The appropriate value of the gap dimension should be set as appropriate according to the size and material of each part of the force sensor 500, but when a moment + my or the like as indicated by a white arrow in FIG. Considering that the force receiving substrate 200 is controlled simultaneously by the upper surface of the pedestal portion 130 and the lower surface of the control substrate 300, it is preferable to set the dimensions of the upper gap and the lower gap equal.

  However, these gap dimensions are generally on the order of 10 to 100 μm, and high-precision machining techniques are required to mass-produce devices having appropriate gap dimensions. Accordingly, a method for mass-producing devices having appropriate gap dimensions by devising the structure of the cylindrical spacer 250 will be described below.

  FIG. 28 is a side sectional view showing a specific configuration example of the cylindrical spacer 250 in the force sensor 500 shown in FIG. As shown on the left side of the figure, the cylindrical spacer 250 shown here is composed of three members 251, 252 and 253. Here, the member 252 is called a main cylindrical member, and the members 251 and 253 are called sub-cylinder members. After all, the cylindrical spacer 250 has a structure in which a main cylindrical member 252 and two sets of auxiliary cylindrical members 251 and 253 are stacked. In the drawing, for convenience of explanation, an example in which the sub-cylindrical members 251 and 253 are respectively disposed above and below the main cylindrical member 252 is shown, but the order of stacking these three cylindrical members may be arbitrary.

  The important point here is that the main cylindrical member 252 is a member having the same thickness as the force receiving substrate 200, and the sub cylindrical members 251 and 253 have the same thickness as the raised portion 111 of the detection substrate. Is a point. Practically, the portion of the detection substrate 100 excluding the raised portion 111 is formed by processing a single flat substrate so that the raised portion 111 prepared as a separate body is joined, and the main cylindrical member 252 is joined. May be cut out from the same material substrate as the force receiving substrate 200, and the sub-cylindrical members 251 and 253 may be cut out from the same material substrate as the raised portions 111. Then, the force receiving substrate 200 and the main tubular member 252 cut out from the same material substrate have the same thickness, and the raised portion 111 and the sub tubular members 251 and 253 cut out from the same material substrate have the same thickness. become.

  If three cylindrical members 251, 252 and 253 having such a thickness are laminated to form a cylindrical spacer 250, and this is inserted between the pedestal portion 130 and the control board 300, it is shown in the figure. The upper gap dimension d1 and the lower gap dimension d2 both match the thicknesses of the sub-cylindrical members 251 and 253, that is, the thickness of the raised portion 111, and the condition d1 = d2 can be satisfied. .

  Note that the main cylindrical member 252 and the force receiving substrate 200 do not necessarily have to be cut out from the same material substrate, and may be made to have the same thickness in a polishing process or the like after being cut out from another material substrate. Similarly, the sub-cylindrical members 251 and 253 and the raised portion 111 do not necessarily have to be cut out from the same material substrate, and may be made to have the same thickness in a polishing process or the like after being cut out from another material substrate.

(2) Control by Column Insertion Hole and Spacer Insertion Hole Until now, the premise that the downward displacement of the force receiving substrate 200 is controlled by the upper surface of the pedestal portion 130 and the upward displacement is controlled by the lower surface of the control substrate 300 However, the displacement of the force receiving substrate 200 can be controlled by another method.

  The first method is a control method by contact between the outer peripheral surface of the force receiving column 210 and the inner peripheral surface of the column insertion hole 310 shown in FIG. Since the displacement of the second object 20 is transmitted to the force receiving substrate 200 via the force receiving column 210, the force receiving column 210 is also inclined when the force receiving substrate 200 is displaced with an inclination. become. Therefore, if the dimension of the cylindrical gap formed between the outer peripheral surface of the force receiving column 210 and the inner peripheral surface of the column insertion hole 310 is set to an appropriate value, the outer peripheral surface and the column of the force receiving column 210 are set. Since the displacement of the force receiving column 210 is limited to the range of the cylindrical gap due to the contact with the inner peripheral surface of the insertion hole 310, the excessive displacement accompanying the inclination of the force receiving substrate 200 is controlled. Can do.

  Of course, when it is not necessary to perform such control, the diameter of the column insertion hole 310 may be set to a sufficiently large dimension. However, if such control is used, the cylindrical gap As long as the dimensions are within the limits of the cylindrical gap, the dimensions of the cylindrical gap are set so that the flexible part 120 and the detection part are not mechanically damaged. You just have to keep it.

  The second method is a control method by contact between the outer peripheral surface of the cylindrical spacer 250 and the inner peripheral surface of the spacer insertion hole 230 shown in FIG. Also in this case, when the force receiving substrate 200 is displaced with an inclination, the spacer insertion hole 230 is also inclined. On the other hand, the cylindrical spacer 250 maintains an upright state on the upper surface of the pedestal portion 130. Therefore, if the dimension of the cylindrical gap formed between the outer peripheral surface of the cylindrical spacer 250 and the inner peripheral surface of the spacer insertion hole 230 is set to an appropriate value, the outer peripheral surface of the cylindrical spacer 250 and the spacer Since the displacement of the spacer insertion hole 230 is limited to the range of the cylindrical gap due to the contact with the inner peripheral surface of the insertion hole 230, the excessive displacement accompanying the inclination of the force receiving substrate 200 is controlled. Can do.

  Of course, when it is not necessary to perform such control, the diameter of the spacer insertion hole 230 may be set to a sufficiently large size. However, if such control is used, the cylindrical gap As long as the dimensions are within the limits of the cylindrical gap, the dimensions of the cylindrical gap are set so that the flexible part 120 and the detection part are not mechanically damaged. You just have to keep it.

(3) Device for alignment of semiconductor substrate In the embodiments described so far, the disk-shaped semiconductor substrate 140 is used as the detection unit. Of course, what is the shape of the semiconductor substrate 140? It doesn't matter. However, in practical use, when mass-producing this apparatus, there are many cases in which a semiconductor substrate 140 cut out from a silicon substrate as a rectangular pellet is used. Here, a device for aligning such a rectangular semiconductor substrate 140 will be described.

  FIG. 29 is a side sectional view showing a detection board 100 ′ used in the first modification of the force sensor 500 shown in FIG. The basic structure of the detection substrate 100 ′ is almost the same as that of the detection substrate 100 described so far, and the reference numerals of corresponding parts are shown with dashes. However, since the semiconductor substrate 140 'is a rectangular pellet, the circular cavity V' for accommodating the semiconductor substrate 140 'is slightly larger than in the previous embodiments.

  When mass-producing an apparatus having such a structure, the alignment of the semiconductor substrate 140 ′ is very important. This is because the position of the piezoresistive element R is determined according to the position of the semiconductor substrate 140 ′, and the position of the piezoresistive element R greatly affects the detection sensitivity. As described above, the stress generated in the flexible portion 120 ′ based on the displacement of the action portion 110 ′ is the portion immediately inside the outer peripheral position P1 of the flexible portion 120 ′ and the outer side of the inner peripheral position P2 of the flexible portion 120 ′. It becomes the largest in the nearest part (that is, the part corresponding to the inside and the outside of the annular groove G2). Therefore, in practical use, a device design is performed such that the piezoresistive element R is disposed at these positions. However, in the actual manufacturing process, the semiconductor substrate 140 ′ is mounted in the circular cavity V ′ surrounded by the inner wall of the pedestal 130 ′ at the position P3. It becomes impossible to attach to the position, and the sensitivity varies.

  Therefore, in the modification shown here, a device for forming an alignment groove as a mark on the bottom surface of the cavity V ′ is devised. FIG. 30 is a bottom view of the detection substrate 100 ′ shown in FIG. 29 (showing a state in which the cover plate 150 ′ is removed. Note that the hatching is for showing the region E1, and does not show a cross section). . The four holes on the pedestal portion 130 ′ shown in the figure are pedestal portion fixing screw holes 160. A rectangular area E1 shown by hatching the bottom surface of the circular cavity V ′ is a substrate arrangement area in which the semiconductor substrate 140 ′ is arranged. In the example shown here, in order to indicate the positions of the four sides of the region E1, a “well” -shaped alignment groove 180 is formed.

  In general, the semiconductor substrate 140 ′ is bonded to the bottom surface of the cavity V ′ using a die bonding agent. In the case of a general example in which the main body portion of the detection substrate 100 is made of metal and the semiconductor substrate 140 ′ is made of a silicon substrate, it is preferable to use a eutectic alloy such as AuSn or AuSi as the die bond agent. When such a eutectic alloy is used, the mechanical strain generated in the flexible portion 120 'can be accurately transmitted to the piezoresistive element R through the semiconductor substrate 140'. Alternatively, a strong organic resin adhesive can be used instead of the eutectic alloy.

  In this way, when the semiconductor substrate 140 ′ is bonded to the bottom surface of the cavity V ′ using a die bond agent, if the “well” -shaped alignment groove 180 is used as a mark, the figure is hatched. In addition, the semiconductor substrate 140 ′ can be accurately aligned and bonded to the correct region E1. In addition, since the alignment groove 180 forms a groove dug in the bottom surface, it also functions as a refuge for dropping excess die bond agent. In the bonding process using a die bond agent, usually, an operation of rubbing the semiconductor substrate 140 ′ against the bottom surface of the cavity V ′ is performed in order to increase the adhesive strength. Come out from. The alignment groove 180 serves as a mark for alignment, and also serves to accommodate excess die bond agent. If only serving as a mark for alignment, “L” -shaped grooves (two orthogonal grooves) may be formed instead of the “well” -shaped grooves.

  FIG. 31 is a side sectional view showing a detection substrate 100 ″ used in the second modification of the force sensor 500 shown in FIG. The basic structure of the detection substrate 100 ″ is almost the same as that of the detection substrate 100 described so far, and the reference numerals of the corresponding parts are shown with two dashes. However, since the semiconductor substrate 140 ″ is a rectangular pellet, the circular cavity V ″ for accommodating the semiconductor substrate 140 ″ is slightly larger than the previous embodiments.

  In the second modification, a peripheral groove G3 is formed as an alignment means when bonding the semiconductor substrate 140 '' to the bottom of the cavity V ''. 32 is a bottom view of the detection substrate 100 ″ shown in FIG. 31 (showing a state in which the cover plate 150 ″ is removed. The hatching is for showing the formation region of the region E2 and the peripheral groove G3. Yes, not a cross section). The four holes on the pedestal portion 130 ″ shown in the figure are pedestal portion fixing screw holes 160. A rectangular region E2 shown by applying single-line hatching to the bottom surface of the circular cavity V ″ is a substrate arrangement region in which the semiconductor substrate 140 ″ is arranged, and is a region shown by applying double-line hatching located around it. Is a region where the peripheral groove G3 is formed. The peripheral groove G3 is a region further dug up around the square region E2. That is, when looking into the circular cavity V ″, the square hill portion protruding in the center is the substrate placement region E2, and the surrounding valley portion is the peripheral groove G3.

  Therefore, also in the case of the second modified example, when the semiconductor substrate 140 ″ is bonded using the die bond agent, the outline of the substrate arrangement region E2 constituting the hill portion can be used as a mark for alignment. In addition, the excess die-bonding agent that oozes out from the periphery of the semiconductor substrate 140 ″ can be processed by being poured into the peripheral groove G3.

10: 1st object 20: 2nd object 30: 1st object 40: 2nd object 100,100 ', 100'': Detection board | substrate 110,110', 110 '': Action part 111: Raised part 120, 120 ′, 120 ″: Flexible portions 130, 130 ′, 130 ″: Base portions 140, 140 ′, 140 ″: Semiconductor substrates 150, 150 ′, 150 ″: Cover plate 160: Base portion fixing Screw hole 161: Main body insertion hole 162: Head receiving hole 170: Screw receiving hole 180: Positioning groove 200: Power receiving substrate 210: Power receiving column 215: Screw receiving hole 220: Tool insertion hole 230: Spacer insertion hole 250 : Cylindrical spacer 251: Sub cylindrical member 252: Main cylindrical member 253: Sub cylindrical member 300: Control board 310: Column insertion hole 320: Tool insertion hole 330: Control board fixing screw hole 331: Main body insertion hole 332 : Head accommodation hole 500: Force sense Sensor 501: first force sensor 502: second force sensor 503: third force sensor 504: fourth force sensor 511: first force sensor 512: second force sensor 513 : Third force sensor 514: fourth force sensor 521: first force sensor 522: second force sensor 523: third force sensor A-A ': cut surface BB' : Cut plane CC ': Cut plane d1, d2: Gap dimension E1, E2: Substrate placement area Fx: Force in the X-axis direction Fy: Force in the Y-axis direction Fz: Force in the Z-axis direction fz, fz1 to fz4: Forces G1, G2 in the z-axis direction: annular groove G3: peripheral groove Mx: moment around the X axis My: moment around the Y axis Mz: moments mx, mx1 to mx4 around the Z axis: moments my, my1 around the x axis ~ My4: moment about y axis O: xyz cubic Origin P1 to P3 of Cartesian coordinate system (local coordinate system): Position Q: Origin of XYZ three-dimensional Cartesian coordinate system (global coordinate system) R: Piezoresistive elements Rx1 to Rx4: Piezoresistive element Ry1 arranged on the x-axis Ry4: Piezoresistive elements Rz1 to Rz4 arranged on the y axis: Piezoresistive elements S1 arranged on an arbitrary axis S1: Force receiving board fixing screw S2: Pedestal fixing screw S3: Control board fixing screw T: Reference circle U center point U: reference circles V, V ′, V ″: cavity Vx, Vy, Vz: potentiometer X: coordinate axis of XYZ three-dimensional orthogonal coordinate system (global coordinate system) x: xyz three-dimensional orthogonal coordinate system (Local coordinate system) coordinate axis Y: XYZ three-dimensional orthogonal coordinate system (global coordinate system) coordinate axis y: xyz three-dimensional orthogonal coordinate system (local coordinate system) coordinate axis Z: XYZ three-dimensional orthogonal coordinate system (global coordinate system) Axis z: coordinate axes xyz three-dimensional orthogonal coordinate system (local coordinate system)

Claims (14)

A force sensor having a function of connecting a first object and a second object, and detecting a force acting on the first object from the second object,
A detection board connected to the first object; a force receiving board connected to the second object; and a control board for controlling displacement of the force receiving board;
The detection substrate is disposed above the first object, the force receiving substrate is disposed above the detection substrate, the control substrate is disposed above the force receiving substrate, and the second object is Placed above the control board,
The detection substrate includes an action part provided at the center, a flexible part provided around the action part, a pedestal part provided around the flexible part, and the movable part. A detecting portion that detects the bending of the bending portion, and the upper end of the action portion constitutes a raised portion that protrudes upward, and the flexible portion connects the action portion and the pedestal portion, The detection unit detects, as an electrical signal, a force acting on the action unit based on a degree of bending of the flexible unit,
A center portion of the lower surface of the force receiving board is fixed to the upper surface of the raised portion, and a force receiving column for connecting to the lower surface of the second object is provided on the upper surface of the force receiving substrate, Is formed with a column insertion hole through which the force receiving column is inserted, and the upper end of the force receiving column is inserted through the column insertion hole,
The control board is fixed to the pedestal portion, and when the second object is displaced with respect to the first object, the displacement is transmitted to the force receiving board via the force receiving column. The force sensor is further configured to be transmitted to the action portion. The force sensor according to claim 1,
The control board is fixed to the pedestal portion with a control board fixing screw, the control board fixing screw is accommodated in a cylindrical spacer, the upper end of the cylindrical spacer is in contact with the lower surface of the control board, and the lower end is the The control board is in contact with the upper surface of the pedestal, and the control board is formed with a control board fixing screw hole for inserting the control board fixing screw and accommodating and holding the screw head. The force sensor is characterized in that a spacer insertion hole is formed through which a spacer is inserted, and a screw receiving hole is formed in the pedestal portion to be screwed with a tip end portion of the control board fixing screw. The force sensor according to claim 2,
The pedestal portion is formed with a pedestal portion fixing screw hole for inserting and holding a pedestal portion fixing screw for fixing the pedestal portion to the first object, and accommodating and holding the screw head. Includes a tool insertion hole for inserting a tool for rotating the head of the pedestal fixing screw from above. The force sensor according to claim 3, wherein
A plurality of force receiving pillars are provided at predetermined locations around the force receiving substrate, a plurality of pedestal fixing screws are formed at predetermined locations on the pedestal, and a plurality of predetermined locations around the control substrate are controlled at a plurality of locations. A force sensor characterized by being fixed by a substrate fixing screw. The force sensor according to claim 4,
A center line that passes through the center of the action part and is orthogonal to each substrate is defined, a reference circle centered on the center line is defined on a projection plane that is orthogonal to the center line, and the reference circle is divided into 12 equal parts. A total of 12 reference points are defined, and each reference point is defined as a first reference point to a twelfth reference point in the order along the reference circle. , 4, 7, and 10 as the B group, and the second, 5, 8, and 11 reference points as the C group,
Four force receiving columns are arranged at the reference point position of the A group, four sets of base fixing screw holes are arranged at the reference point position of the B group, and four control board fixing screws are arranged in the C group. A force sensor arranged at a reference point position. In the force sensor according to any one of claims 3 to 5,
A screw receiving hole is formed at the upper end of the force receiving column so as to be screwed with the tip of a force receiving substrate fixing screw whose head is fixed to the second object. The upper end is located above the upper surface of the control substrate. Stick out,
The control board fixing screw hole is formed in the upper part of the main body part insertion hole, and the main body part insertion hole having a diameter that can be inserted through the main body part of the control board fixing screw but not through the head part. A head receiving hole having a diameter necessary to receive the head of the control board fixing screw, and
The pedestal part fixing screw hole is formed in the upper part of the main body part insertion hole with a main body part insertion hole having a diameter that can be inserted through the main body part of the pedestal part fixing screw but cannot be inserted through the head part, A force sensor comprising: a head receiving hole having a diameter required to receive the head of the base fixing screw. The force sensor according to any one of claims 3 to 6,
A predetermined upper gap is secured between the periphery of the upper surface of the force receiving board and the periphery of the lower surface of the control board, and a predetermined lower gap is provided between the periphery of the lower surface of the force receiving board and the upper surface of the pedestal portion. The displacement of the force receiving substrate is limited within the range of the upper gap and the lower gap, and the dimensions of the upper gap and the lower gap are such that the displacement under the restriction is A force sensor characterized in that it is set within a range in which no mechanical damage occurs in the flexible part and the detection part as long as it occurs. The force sensor according to claim 7, wherein
The cylindrical spacer is constituted by a structure in which a main cylindrical member and two sets of sub cylindrical members are stacked, the main cylindrical member has the same thickness as the force receiving substrate, and the sub cylindrical member is a detection substrate. A force sensor having the same thickness as a raised portion, wherein the thickness of the sub-cylindrical member matches the size of the upper gap and the lower gap. The force sensor according to any one of claims 1 to 8,
A predetermined cylindrical gap is secured between the outer peripheral surface of the force receiving column and the inner peripheral surface of the column insertion hole, and the displacement of the force receiving column is limited within the range of the cylindrical gap. And the dimension of the cylindrical gap is set within a range in which no mechanical damage is caused to the flexible part and the detection part as long as the displacement under the restriction occurs. Sensor. The force sensor according to any one of claims 2 to 8,
A predetermined cylindrical gap is secured between the outer peripheral surface of the cylindrical spacer and the inner peripheral surface of the spacer insertion hole, and the displacement of the force receiving substrate is limited within the range of the cylindrical gap. And the dimension of the cylindrical gap is set within a range in which no mechanical damage is caused to the flexible part and the detection part as long as the displacement under the restriction occurs. Sensor. The force sensor according to any one of claims 1 to 10,
The flexible part is arranged so as to surround the periphery of the action part, and is constituted by an annular thin part having a thickness that exhibits flexibility,
A detection unit is bonded to the annular thin part and causes deflection with the annular thin part, a piezoresistive element formed in the semiconductor substrate, and an action part based on a change in the resistance value of the piezoresistive element A force sensor comprising: a circuit that outputs a force acting on the sensor as an electrical signal. The force sensor according to any one of claims 1 to 11,
An xyz three-dimensional orthogonal coordinate system in which an origin O is defined on a center line that passes through the center of the action part and is orthogonal to each substrate, the center line is the z axis, and two axes that are orthogonal to the center line are the x axis and the y axis. When defined
A force sensor, wherein the detection unit has a function of detecting a moment mx about the x-axis, a moment my about the y-axis, and a force fz in the z-axis direction that acted on the action unit. A plurality of force sensors according to claim 12, and an arithmetic circuit that performs an operation based on detection values output from the plurality of force sensors.
In an XYZ three-dimensional orthogonal coordinate system having an origin Q, a force Fx in the X-axis direction, a force Fy in the Y-axis direction, a force Fz in the Z-axis direction, and an X-axis force acting on the first object from the second object A six-dimensional force detection device having a function of detecting six components of a moment Mx around, a moment My around the Y axis, and a moment Mz around the Z axis,
Each pedestal portion of the plurality of force sensors is fixed to a first object at a predetermined position in the XYZ three-dimensional orthogonal coordinate system, and each force receiving column of the plurality of force sensors is Each fixed to a second object at a predetermined position in the XYZ three-dimensional orthogonal coordinate system;
6. The six-dimensional force detection apparatus according to claim 1, wherein the arithmetic circuit performs an operation for obtaining the values of the six components based on detection values mx, my, and fz detected by the force sensors. The six-dimensional force detection device according to claim 13,
A first force sensor having an origin O arranged on the positive X axis of the XYZ three-dimensional orthogonal coordinate system; a second force sensor having an origin O arranged on the negative X axis; A third force sensor having an origin O arranged on an axis and a fourth force sensor having an origin O arranged on a negative Y axis, and the x-axis, y of each force sensor The axis and the z axis are arranged so as to be parallel to the X axis, the Y axis, and the Z axis of the XYZ three-dimensional orthogonal coordinate system, respectively.
The arithmetic circuit detects the moment around the x axis detected by the first force sensor as mx1, the moment around the y axis as my1, and the force in the z axis direction as fz1, and is detected by the second force sensor. The moment about the x-axis is mx2, the moment about the y-axis is my2, the force in the z-axis direction is fz2, the moment about the x-axis detected by the third force sensor is mx3, and the moment about the y-axis Is my3, the z-axis direction force is fz3, the x-axis moment detected by the fourth force sensor is mx4, the y-axis moment is my4, and the z-axis direction force is fz4. ,
Fx = my1 + my2 + my3 + my4 or = my1 + my2 or = my3 + my4
Fy = mx1 + mx2 + mx3 + mx4 or = mx1 + mx2 or = mx3 + mx4
Fz = fz1 + fz2 + fz3 + fz4 or = fz1 + fz2 or = fz3 + fz4
Mx = fz3-fz4
My = fz2-fz1
Mz = -mx1 + mx2-my3 + my4 or = -mx1 + mx2 or = -my3 + my4
A six-dimensional force detection device characterized in that a value of six components is obtained by the following calculation.

Images