JP3144757U - Force sensor - Google Patents

Abstract

Provided is a force sensor having a structure in which a thin portion is not damaged even when an excessive external force is applied.
A second substrate is disposed below the first substrate, and a third substrate is bonded to the second substrate. The thin portions 115 and 125 of the first substrate 100 and the thin portions 215 and 225 of the second substrate 200 are connected by columnar bodies T1 and T2. When an external force is applied to the first substrate 100 with the second substrate 200 fixed, the columnar bodies T1 and T2 are inclined and the thin portions 215 and 225 are deformed. This deformation is measured by deformation measuring units S1 and S2 made of a capacitive element, and an external force is detected. Concave portions H21 and H22 are dug around the first substrate 100, and through holes H11 and H12 having smaller diameters are formed on the bottom surfaces thereof. Locking pins 51 and 52 whose lower ends are fixed to the upper surface of the second substrate 200 are inserted into the through holes H11 and H12, and a stopper member having a diameter larger than that of the through hole is attached to the head.
[Selection] Figure 1

Description

  The present invention relates to a force sensor, and more particularly, to a force sensor of a type that causes a thin portion having flexibility based on an external force to be detected to bend and electrically detects the deformation state.

  A force sensor of a type that detects the magnitude and direction of the applied external force by applying an external force to the flexible thin part and electrically detecting the deformation state of the thin part has been put into practical use. . This type of sensor has a relatively simple structure and can be manufactured at a low cost. Therefore, it is used as a mass-produced product in various industrial fields. Further, if a force based on acceleration is detected as an external force, it can be applied to an acceleration sensor, and if a Coriolis force is detected as an external force, it can be applied to an angular velocity sensor.

  As a method for electrically detecting the deformation state of the thin portion, a method using a capacitive element, a method using a piezoresistive element, a method using a piezoelectric element, and the like have been proposed. By arranging each of these elements at a plurality of locations and detecting the displacement of each position of the thin portion as an electrical signal, the magnitude of each coordinate axis direction component of the applied external force is independent in the XYZ three-dimensional orthogonal coordinate system. Can be detected.

  For example, in Patent Documents 1 and 2 below, it is possible to independently detect the force acting in the direction of each coordinate axis by detecting the displacement of each part of the thin part using a capacitive element. A multidimensional force sensor is disclosed. Patent Documents 3 and 4 disclose a multidimensional force sensor that detects a force in each coordinate axis direction based on a change in electric resistance of a piezoresistive element provided at each position of a thin portion. In Patent Documents 5 and 6, the displacement of each part of the thin part is detected based on the electric charge generated in the piezoelectric element, and the acceleration based on the acceleration acting as an external force or the Coriolis force is detected. A multi-axis sensor that detects angular velocity around each coordinate axis is disclosed.

Furthermore, in Patent Documents 7 and 8 below, by detecting independently the deflection generated in the plurality of thin portions, the moment acting around the XYZ axis is detected together with the force acting in the XYZ axis direction. A six-axis sensor capable of the above is disclosed.
JP-A-4-148833 JP 2001-165790 A JP-A-6-174571 JP 2004-69405 A JP-A-8-226931 JP 2002-71705 A JP 2004-325367 A JP 2004-354049 A

  In the force sensor of the type described above, in order to increase the force detection sensitivity, it is necessary to increase the flexibility by reducing the thickness dimension of the thin portion or by using a material that is easily bent. On the other hand, in order to increase the robustness, it is necessary to increase the thickness dimension of the thin part or to make the thin part difficult to bend to reduce the flexibility. For this reason, when designing a force sensor, a thin portion that matches the force measurement range according to the application is incorporated.

  However, even if a force sensor corresponding to a predetermined measurement range according to the application is designed, in practice, an external force within the measurement range does not always act, and an excessive external force is applied for some reason. It is inevitable that the situation will end up. In this way, if an excessive external force that far exceeds the measurement range is applied to the force sensor, excessive deformation exceeding the elastic deformation limit will occur in the thin part, and after the external force is removed However, the thin part may not be restored to its original shape, or the thin part may be damaged. In particular, in the case of a high-sensitivity force sensor incorporating a delicate thin part that causes bending even with a slight external force, the thin part is likely to be damaged when an excessive external force is applied. For this reason, in practical use, it is necessary to design a product in consideration of the balance between detection sensitivity and robustness, and it is necessary to pay sufficient attention to the handling of products that place importance on detection sensitivity.

  In view of the above, an object of the present invention is to provide a force sensor having a structure in which a thin portion is not damaged even when an excessive external force is applied.

(1) The first aspect of the present invention is a force sensor,
A first substrate in which a flexible upper end side thin portion is formed in each of a plurality of locations;
The second substrate is disposed so as to be opposed to the lower portion of the first substrate at a predetermined interval, and a flexible lower end side thin portion is formed at a position facing each upper end thin portion. A substrate,
A plurality of columnar bodies that mutually connect the lower surface of the upper end side thin portion and the upper surface of the lower end side thin portion with respect to the upper end side thin portion and the lower end side thin portion at positions facing each other,
A deformation measuring unit for electrically measuring a deformation state of each lower end side thin portion or each upper end side thin portion by the external force when an external force is applied to the first substrate in a state where the second substrate is fixed; ,
A detection circuit for detecting the direction and magnitude of the external force based on the measurement result of the deformation measuring unit;
Composed by
In a predetermined portion of the peripheral portion of the first substrate, a concave portion having a predetermined diameter is formed by digging to a predetermined depth from the upper surface side,
The bottom surface of the recess has a diameter smaller than the diameter of the recess, and a through-hole penetrating to the lower surface of the first substrate is formed,
The through hole is inserted with a locking pin whose lower end is fixed to the upper surface of the second substrate,
This locking pin is "a column member that extends upward from the upper surface of the second substrate, has an upper end protruding upward by a predetermined dimension from the bottom surface of the recess, and has a diameter smaller than the diameter of the through-hole" and "this column member And a stopper member having a diameter larger than the diameter of the through hole and smaller than the diameter of the concave portion.

(2) A second aspect of the present invention is the force sensor according to the first aspect described above,
The columnar body is composed of an integral structure made of the same material as the upper end side thin portion and extends downward from the upper end side thin portion, and an integral structure of the same material as the lower end thin portion, and the lower end And a lower columnar protrusion extending upward from the side thin portion ”.

(3) A third aspect of the present invention is the force sensor according to the first or second aspect described above,
A third substrate bonded to the lower surface of the second substrate;
A lower end side thin portion made of a conductive material is disposed above the lower surface of the second substrate by a predetermined dimension so as to ensure a predetermined space between the upper surface of the third substrate,
A plurality of electrodes are formed on the opposing portion of the lower end side thin portion of the upper surface of the third substrate,
The deformation measurement unit is configured to measure the deformation state of the lower end side thin portion by electrically detecting the capacitance between the lower end side thin portion and each of the plurality of electrodes.

(4) A fourth aspect of the present invention is the force sensor according to the first to third aspects described above,
The through hole is formed of a cylindrical cavity having an inner diameter φ10, the concave portion is formed of a cylindrical cavity having an inner diameter φ20, the support member is formed of a cylindrical member having an outer diameter φ30, and the stopper member is an outer diameter It consists of a cylindrical member with φ40,
In a state where no external force is applied to the first substrate, the concentric arrangement is made such that the central axes of the respective cylinders constituting the through hole, the concave portion, the column member, and the stopper member coincide with each other, and φ30 <φ10 <φ40 <φ20. It is what is set.

(5) A fifth aspect of the present invention is the force sensor according to the first to fourth aspects described above,
When two placement axes that are orthogonal to each other at the center point and a circle with a radius r centered on the center point are defined on the upper surface of the second substrate, the circle and the two placement axes intersect. Four strut members are arranged at the four intersection positions, and a stopper member is fixed to the upper end of each strut member,
In the first substrate, through holes and recesses are respectively provided at four locations suitable for inserting the four support members.

  According to the force sensor of the present invention, the displacement of the first substrate that receives the action of the external force is limited within a predetermined range by the upper surface of the second substrate and the locking pin, so that an excessive external force acts. However, the displacement of the first substrate is suppressed within a safe allowable range. Therefore, it is possible to realize a structure in which no trouble occurs in the thin portion even when an excessive external force is applied.

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

<<< §1. Components of basic embodiment >>
FIG. 1 is a side sectional view of a force sensor according to a basic embodiment of the present invention, and FIG. 2 is an enlarged side sectional view of an upper right portion of the force sensor shown in FIG. Here, for convenience of explanation, as shown in FIG. 1, an origin O is defined at the substantially central position of the force sensor, and XYZ three-dimensional orthogonal coordinates having an X axis, a Y axis, and a Z axis in the illustrated directions. The system will be defined and the following explanation will be given. FIG. 1 is a side sectional view showing a state in which the force sensor is cut along the XZ plane, and the Y-axis is oriented in a direction perpendicular to the paper surface.

  FIG. 3 is a side sectional view showing a state where the force sensor shown in FIG. 1 is disassembled into parts. Here, first, the structure of each part will be described with reference to FIG. As illustrated, the basic components of the force sensor are a first substrate 100, a second substrate 200, and a third substrate 300. Here, the 1st board | substrate 100, the 2nd board | substrate 200, and the 3rd board | substrate 300 are square plate-shaped components which have the same planar shape. On the other hand, the locking pins 51 and 52 are additional components that are attached to control the displacement of the first substrate 100, as will be described later.

  FIG. 4 is a top view of the first substrate 100. As illustrated, the first substrate 100 is a disk-shaped component having a square planar shape. Cylindrical recesses H21 to H24 are dug in four places (X-axis upper position and Y-axis upper position) around the upper surface, and a cylindrical through hole with a smaller diameter is formed on the bottom surface. Holes H11 to H14 are formed.

  The positional relationship between the recesses H21 to H24 and the through holes H11 to H14 is clearly shown in the side sectional view of FIG. 3 (FIG. 3 is a side sectional view along the XZ plane. Only H22 and through holes H11, H12 are shown). The cylinders constituting the through holes H11 to H14 and the cylinders constituting the recesses H21 to H24 are concentrically arranged with a common central axis. Further, if the diameter of the cylinder constituting the through holes H11 to H14 is φ10 and the diameter of the cylinder constituting the recess is φ20, then φ10 <φ20.

  As indicated by broken lines in FIG. 4, doughnut-shaped grooves are dug in four places (X-axis upper position and Y-axis upper position) on the lower surface side of the first substrate 100. Upper columnar protrusions 110, 120, 130, and 140 are provided inside the groove, and the upper portion of the donut-shaped groove constitutes upper-end-side thin portions 115, 125, 135, and 145. In FIG. 4, the outer circumference circles of the upper columnar projections 110, 120, 130, and 140 and the outer circumference circles of the upper end side thin portions 115, 125, 135, and 145 are concentric circles having a common center point.

  The positional relationship between the upper columnar protrusions 110, 120, 130, and 140 and the upper end side thin portions 115, 125, 135, and 145 is clearly shown in the side sectional view of FIG. 3 (FIG. 3 shows the XZ plane). Only the upper columnar protrusions 110, 120 and the upper end side thin portions 115, 125 are shown). The thickness of the upper end side thin portions 115, 125, 135, and 145 is set to a dimension sufficient to produce flexibility. The smaller the thickness dimension, the greater the flexibility but the lower the robustness. As the thickness dimension increases, the flexibility decreases but the robustness increases.

  On the other hand, FIG. 5 is a top view of the second substrate 200. As illustrated, the second substrate 200 is also a disk-shaped component having a square planar shape. Symmetrical donut-shaped grooves are dug in four locations on the upper surface (X-axis upper position and Y-axis upper position) so as to face the donut-shaped grooves dug in the lower surface of the first substrate 100. The lower columnar protrusions 210, 220, 230, and 240 are provided inside the donut-shaped groove, and the lower portion of the donut-shaped groove is provided with lower-end thin portions 215, 225, 235, and 245. It is composed. In FIG. 5, the outer circumference circles of the lower columnar projections 210, 220, 230, and 240 and the outer circumference circles of the upper end side thin portions 215, 225, 235, and 245 are concentric circles having a common center point.

  The positional relationship between the lower columnar projections 210, 220, 230, and 240 and the lower end side thin portions 215, 225, 235, and 245 is clearly shown in the side sectional view of FIG. 3 (FIG. 3 shows the XZ plane). Only the lower columnar protrusions 210 and 220 and the lower end thin portions 215 and 225 are shown). The thickness of the lower end side thin portions 215, 225, 235, and 245 is set to a dimension sufficient to produce flexibility. The smaller the thickness dimension, the greater the flexibility but the lower the robustness. As the thickness dimension increases, the flexibility decreases but the robustness increases.

  As shown in FIG. 3, the upper end side thin portions 115, 125, 135, and 145 are formed at the upper surface position of the first substrate 100, whereas the lower end side thin portions 215, 225, 235, and 245 are formed. Is formed at a substantially intermediate position between the upper surface and the lower surface of the second substrate 200. Therefore, cylindrical hollow portions are respectively formed below the lower end side thin portions 215, 225, 235, and 245. In this hollow portion, as will be described later, a deformation measuring portion is formed.

  FIG. 6 is a top view of the third substrate 300. As illustrated, the third substrate 300 is also a disk-shaped component having a square planar shape. As shown in the drawing, a total of 20 electrodes E11 to E45 are arranged on the upper surface. The 20 electrodes are divided into 4 electrode groups each having 5 sheets as shown. The five electrodes E11 to E15 belonging to the first group are arranged at positions facing the lower columnar protrusion 210 and the lower end thin portion 215, and are used for measuring the deformation state of the lower end thin portion 215. The The five electrodes E21 to E25 belonging to the second group are arranged at positions facing the lower columnar projection 220 and the lower end thin part 225, and are used for measuring the deformation state of the lower end thin part 225. The The five electrodes E31 to E35 belonging to the third group are disposed at positions facing the lower columnar protrusion 230 and the lower end thin portion 235, and are used for measuring the deformation state of the lower end thin portion 235. The The five electrodes E41 to E45 belonging to the fourth group are arranged at positions facing the lower columnar protrusion 240 and the lower end thin portion 245, and are used for measuring the deformation state of the lower end thin portion 245. The

  Of the five electrodes belonging to each group, one is a circular electrode with a center point on the extension of the central axis of the lower columnar projection, and the remaining four are arranged to surround the periphery This is a fan-shaped electrode. For example, in FIG. 6, the electrode E15 is a circular electrode having a center point on the extension line of the central axis of the lower columnar protrusion 210, and the electrodes E11 to E14 are fan-shaped electrodes arranged at positions surrounding the periphery. Electrode.

  The first substrate 100 is preferably made of a metal such as stainless steel, aluminum, titanium, or the like because the upper end side thin portion needs to be made of a material having sufficient flexibility for measurement. In addition, the second substrate 200 needs to be formed of a conductive material because the lower end side thin portion has sufficient flexibility for measurement, and is also formed of a metal such as stainless steel, aluminum, titanium, or the like. It is preferable to do this. On the other hand, since it is necessary to form the 20 electrodes E11 to E45 shown in FIG. 6 on the upper surface of the third substrate 300, in order to prevent these electrodes from being short-circuited with each other, for example, an insulating material such as ceramics is used. It is preferable to use a substrate. Although not shown in FIG. 6, the electrodes E <b> 11 to E <b> 45 are wired to an external detection circuit on the upper surface of the third substrate 300.

  As shown in FIG. 3, above the five electrodes E11 to E15 belonging to the first group, a lower end side thin portion 215 made of a conductive material is arranged to face each other with a predetermined interval. . For this reason, the capacitive elements C11 to C15 are formed by the electrodes E11 to E15 and the opposing regions of the lower end side thin portion 215. The capacitance elements C11 to C15 function as a deformation measuring unit S1 that electrically measures the deformation state of the lower end side thin portion 215. Further, the capacitance elements C21 to C25 formed by the five electrodes E21 to E25 belonging to the second group and the opposing regions of the lower end side thin portion 225 disposed above the electrodes are the lower end side thin portion. It functions as a deformation measuring unit S2 that electrically measures the deformation state of 225. Similarly, the capacitance elements C31 to C35 formed by the five electrodes E31 to E35 belonging to the third group and the opposing regions of the lower end side thin portion 235 arranged above the electrodes are the lower end side thin portion. Each of the opposing regions of the five electrodes E41 to E45 belonging to the fourth group and the lower-side thin part 245 disposed above the functioning as a deformation measuring unit S3 that electrically measures the deformation state of the unit 235 The electrostatic capacitance elements C41 to C45 formed by the above function as a deformation measuring unit S4 that electrically measures the deformation state of the lower end side thin portion 245.

  A detection circuit (not shown) provided outside has a function of detecting the direction and magnitude of the external force applied to the first substrate 100 based on the measurement results of the deformation measurement units S1 to S4.

<<< §2. Structure of basic embodiment >>
The force sensor shown in FIG. 1 has the first substrate 100, the second substrate 200, and the third substrate 300 shown in FIG. 3 joined in an up-and-down direction, and further, locking pins 51 to 54 are attached. Is. That is, the first substrate 100 and the second substrate 200 are joined by joining the lower ends of the upper columnar protrusions 110, 120, 130, and 140 to the upper ends of the lower columnar protrusions 210, 220, 230, and 240, respectively. Made by doing. At this time, the lower ends of the upper columnar protrusions 110, 120, 130, and 140 protrude slightly below the lower surface of the first substrate 100, and the upper ends of the lower columnar protrusions 210, 220, 230, and 240 are Since it protrudes slightly above the upper surface of the second substrate 200, the lower surface of the first substrate 100 and the upper surface of the second substrate 200 are parallel to each other while a predetermined gap is secured. A dimension L1 shown in FIG. 2 indicates the dimension of the gap.

  After all, it consists of an integral structure of the same material as the upper end side thin portion 115, an upper columnar projection 110 extending downward from the upper end thin portion 115, and an integral structure of the same material as the lower end thin portion 215, and the lower end side. One column is formed by joining the lower columnar protrusion 210 extending upward from the thin portion 215. Hereinafter, this column is referred to as a columnar body T1. Similarly, a column obtained by joining the upper columnar projection 120 and the lower columnar projection 220 is called a columnar body T2, and a column obtained by joining the upper columnar projection 130 and the lower columnar projection 230. Is called a columnar body T3, and a column obtained by joining the upper columnar protrusion 140 and the lower columnar protrusion 240 is called a columnar body T4.

  On the other hand, the lower surface of the second substrate 200 is bonded to the upper surface of the third substrate 300. As described above, columnar cavities are formed below the lower end side thin portions 215, 225, 235, and 245, and the electrodes E11 to E45 are accommodated in the cavities.

  Further, the locking pins 51 to 54 are inserted into the through holes H11 to H14, and the lower ends thereof are fixed to the upper surface of the second substrate 200. As shown in FIG. 3, the locking pin 51 includes a columnar column member 31 having a diameter φ30 and a columnar stopper member 41 having a diameter φ40. It is constituted by a columnar column member 32 having φ30 and a columnar stopper member 42 having a diameter φ40. Although illustration is omitted, the locking pins 53 and 54 have the same structure. As illustrated, each stopper member is fixed to a concentric position at the upper end of each column member. In the example shown here, the locking pins 51 to 54 are made of a metal such as stainless steel, and are fixed to the upper layer portion of the second substrate 200 using screws or the like.

  As shown in the enlarged side sectional view of FIG. 2, the through hole H11 is formed of a cylindrical cavity having an inner diameter φ10, the concave portion H21 is formed of a cylindrical cavity having an inner diameter φ20, and the column member 31 is externally provided. The stopper member 41 is made of a columnar member having an outer diameter φ40. Then, in a state where no external force is applied to the first substrate 100, a concentric arrangement is made such that the central axes of the respective cylinders constituting the through hole H11, the recess H21, the support member 31, and the stopper member 41 coincide with each other, and φ30 <Φ10 <φ40 <φ20 is set. Further, in the state where no external force is applied to the first substrate 100, a gap dimension L1 is secured between the lower surface of the first substrate 100 and the upper surface of the second substrate 200, and the bottom surface of the recess H21. And the lower surface of the stopper member 41 have a gap dimension L2. The structure around the locking pins 52, 53, and 54 attached to the other three locations is exactly the same.

  As described above, FIG. 4 is a top view of the first substrate 100, and the through holes H11 to H14 are provided at four locations in the peripheral portion. The locking pins 51 to 54 are fixed to the upper surface of the second substrate 200 in a state of being inserted through the through holes H11 to H14, respectively. Therefore, when two arrangement axes perpendicular to the center point and a circle with a radius r centering on the center point are defined on the upper surface of the second substrate 200, the lower portions of the locking pins 51 to 54 are defined. The four strut members 31 to 34 constituting the are arranged at four intersection positions where the circle and the two arrangement axes intersect. The through holes H11 to H14 and the recesses H21 to H24 provided in the first substrate 100 are arranged at positions suitable for inserting the four column members 31 to 34, and the column members 31 to 34 are disposed. The stopper members 41 to 44 fixed to the upper ends of the recesses fit in the center positions of the recesses H21 to H24, respectively.

After all, the main components of the force sensor shown in FIG. 1 are as follows.
(1) First substrate 100 in which upper-end thin portions 115, 125, 135, and 145 having flexibility are formed at four locations, respectively.
(2) The first substrate 100 is disposed below the first substrate 100 with a predetermined interval L1 so as to be opposed to each other, and has flexibility at positions opposed to the respective upper end side thin portions 115, 125, 135, 145. The second substrate 200 on which the lower end side thin portions 215, 225, 235, 245 are formed.
(3) Columnar bodies T1, T2, which respectively connect the lower surfaces of the upper-side thin portions 115, 125, 135, 145 and the upper surfaces of the lower-side thin portions 215, 225, 235, 245 at the positions facing each other. T3, T4
(4) Third substrate 300 bonded to the lower surface of second substrate 200
(5) When the external force is applied to the first substrate 100 in a state where the second substrate 200 is fixed, each lower-side thin portion generated by the force transmitted from each columnar body T1, T2, T3, T4 Deformation measuring units S1 to S4 that electrically measure the deformation state of 215, 225, 235, and 245 (specifically, the lower end side thin portions 215, 225, 235, and 245 having conductivity, and facing them) Electrodes E11 to E45)
(6) A detection circuit (not shown) for detecting the direction and magnitude of the applied external force based on the measurement results of the deformation measuring units S1 to S4.

  Moreover, in this force sensor, “recesses H21 to H24 that are dug to a predetermined depth from the upper surface side and have a predetermined diameter φ20” are formed at predetermined locations around the first substrate 100. Further, In the bottom surfaces of the recesses H21 to H24, “through holes H11 to H14 having a diameter φ10 smaller than the recess diameter φ20 and penetrating to the lower surface of the first substrate 100” are formed. Then, through the through holes H11 to H14, locking pins 51 to 54 whose lower ends are fixed to the upper surface of the second substrate 200 are inserted. Here, the locking pins 51 to 54 are “extending upward from the upper surface of the second substrate 200, the upper ends projecting upward from the bottom surfaces of the recesses H 21 to H 24 by a predetermined dimension L 2, and the diameter φ10 of the through holes H 11 to H 14. Column member 31 to 34 having a smaller diameter φ30 ”and“ having a diameter φ40 that is connected to the upper ends of the column members 31 to 34 and is larger than the diameter φ10 of the through holes H11 to H14 and smaller than the diameter φ20 of the recess. Stopper members 41 to 44 ".

<<< §3. Displacement control in basic embodiment >>
Next, it will be described that in the force sensor having the structure shown in FIG. 1, the displacement control of the first substrate 100 that directly receives the action of the external force is appropriately performed. The basic principle of force detection by the force sensor is that an external force is applied to the first substrate 100 in a state where the second substrate 200 and the third substrate 300 are fixed, and each thin portion is bent. The deformation state of the lower end side thin portions 215, 225, 235, 245 is measured by the deformation measurement units S1 to S4, and the direction and magnitude of the applied external force are detected by the detection circuit.

  The greater the external force that acts on the first substrate 100, the greater the displacement of the first substrate 100. As a result, the degree of deformation that occurs in each thin portion increases. However, as described above, if an excessive external force far exceeding the measurement range is applied, each thin section will be excessively bent beyond its elastic deformation limit. There is a problem that the shape of the thin portion does not return to its original shape, or the thin portions are damaged. The force sensor shown in FIG. 1 has a structure that suppresses the amount of displacement of the first substrate 100 within an allowable range. Therefore, even if an excessive external force is applied, the displacement of the first substrate 100 is It is controlled and has a function of preventing the occurrence of failure in each thin portion.

  For example, FIG. 7 is a side sectional view showing displacement control when a force + Fz in the positive direction of the Z axis is applied to the first substrate 100. The force + Fz in the positive direction of the Z axis is a force that displaces the first substrate 100 upward as shown in the figure, and each thin portion is bent as shown in the figure. In the case of this force sensor, the displacement in the positive direction of the Z-axis is controlled so as to be at most the gap dimension L2 shown in FIG. This is because when the first substrate 100 is displaced by L2 in the positive direction of the Z-axis, as shown in FIG. 7, the bottom peripheral portions of the concave portions H21 to H24 form the heads of the locking pins 51 to 54. This is because it abuts on the periphery of the lower surface of ˜44 and prevents further upward displacement. If the gap dimension L2 is set to an appropriate value, the upward displacement of the first substrate 100 can be suppressed within a range in which each thin portion is not damaged.

  On the other hand, FIG. 8 is a side sectional view showing displacement control when a force −Fz in the negative Z-axis direction acts on the first substrate 100. As shown in the drawing, the Z-axis negative direction force -Fz is a force that displaces the first substrate 100 downward, and each thin portion is bent as shown in the drawing. In the case of this force sensor, the displacement in the negative Z-axis direction is controlled so as to be at most the gap dimension L1 shown in FIG. This is because when the first substrate 100 is displaced by L1 in the negative Z-axis direction, the lower surface of the first substrate 100 comes into contact with the upper surface of the second substrate 200 as shown in FIG. This is to prevent displacement. If the gap dimension L1 is set to an appropriate value, the downward displacement of the first substrate 100 can be suppressed within a range in which each thin portion is not damaged.

  Next, consider the case where a moment is applied. FIG. 9 shows the moment + My about the first substrate 100 around the Y-axis positive direction (here, the rotational direction for advancing the right screw in the Y-axis positive direction is called the Y-axis positive direction). It is a sectional side view which shows the displacement control when acted. As shown in the drawing, the moment + My about the positive direction of the Y-axis is a force that displaces the right end of the first substrate 100 downward and the left end upward, and each thin portion is bent as shown in the drawing. become. In this force sensor, the displacement based on such moment + My is controlled so as to be in the state shown in FIG. 9 at the maximum. This is because when the right end of the first substrate 100 is displaced downward, as shown in FIG. 9, its lower surface abuts on the upper surface of the second substrate 200, preventing further downward displacement, and When the left end of one substrate 100 is displaced upward, as shown in FIG. 9, the peripheral portion of the bottom surface of the recess H22 comes into contact with the peripheral portion of the lower surface of the stopper member 42 that forms the head of the locking pin 52. This is to prevent the upward displacement of.

  On the contrary, when the moment -My around the Y-axis negative direction is applied, the state is reversed left and right in FIG. 9, and similarly, the displacement is controlled within a predetermined allowable range. The force sensor maintains the same structure even if it is rotated 90 ° on the XY plane, and the same phenomenon occurs even if the X axis and the Y axis are interchanged. Therefore, the same displacement control is performed even when the moments + Mx, −Mx around the X axis are applied.

  On the other hand, FIG. 10 is a side sectional view showing displacement control when a force + Fx in the positive direction of the X-axis is applied to the first substrate 100. As shown in the figure, the X-axis positive direction force + Fx is a force that displaces the first substrate 100 in the right direction in the drawing, and the thin portions are bent as shown in the drawing. In the case of this force sensor, the displacement in the X-axis positive direction is controlled so as to be in the state shown in FIG. 10 at the maximum. This is because when the first substrate 100 is displaced in the X-axis positive direction to the position shown in the drawing, the side walls of the recesses H21 to H24 abut against the outer peripheral surfaces of the stopper members 41 to 44 forming the heads of the locking pins 51 to 54. This is to prevent further displacement to the right. FIG. 11 is a top view showing the state of FIG. 10 and clearly shows a state in which the side walls of the four recesses H21 to H24 are in contact with the outer peripheral surfaces of the stopper members 41 to 44, respectively.

  On the contrary, when the force -Fx in the negative X-axis direction is applied, the state is reversed left and right in FIG. 10, and similarly, the displacement is controlled within a predetermined allowable range. The same displacement control is also performed when a force + Fy in the Y-axis positive direction or a force -Fy in the Y-axis negative direction is applied. As described above, since the inner diameter of the recesses H21 to H24 is φ20 and the outer diameter of the stopper members 41 to 44 is φ40, the displacement in the positive or negative direction with respect to the X axis and the Y axis is eventually “(φ20− It is controlled to a value of “φ40) / 2”. Therefore, if the dimension values φ20 and φ40 are set to appropriate values, the displacement of the first substrate 100 in the horizontal direction can be suppressed within a range in which each thin portion is not damaged.

  Finally, consider the case where a moment around the Z axis is applied. FIG. 12 is a top view showing displacement control when a moment + Mz around the positive direction of the Z-axis is applied to the first substrate 100. As shown in the drawing, the moment + Mz about the positive direction of the Z-axis is a force that rotates and displaces the first substrate 100 counterclockwise when viewed from above. In this force sensor, the displacement based on the moment + Mz is controlled so as to be in the state shown in FIG. 12 at the maximum. This is because when the first substrate 100 is rotationally displaced counterclockwise, the side walls of the four recesses H21 to H24 come into contact with the outer peripheral surfaces of the stopper members 41 to 44, respectively, as shown in the figure. This is to prevent rotational displacement around.

  Conversely, when the moment -Mz around the negative Z-axis direction is applied, the first substrate 100 is rotationally displaced clockwise when viewed from above. In this case as well, the side walls of the four recesses H21 to H24 abut against the outer peripheral surfaces of the stopper members 41 to 44, respectively, and further clockwise displacement is prevented.

  Thus, in the force sensor shown in FIG. 1, the force ± Fx in the X-axis direction, the force ± Fy in the Y-axis direction, the force ± Fz in the Z-axis direction, and the moment ± about the X-axis are applied to the first substrate 100. Regardless of which of Mx, the moment about the Y axis ± My, or the moment about the Z axis ± Mz, the displacement is suppressed within a predetermined allowable range. As described above, it is a very important effect that the displacement control with respect to the first substrate 100 is accurately performed regardless of any of the force in the direction of each coordinate axis and the moment around each coordinate axis.

  When a force sensor is incorporated into a product and actually used, not only the normal operating environment for detecting the external force that is the original measurement target, but also the user hits the product itself or drops it on the floor. It is necessary to take into account the emergency situation. In such an emergency, it is impossible to predict what impact force will be applied to the force sensor from which direction. In the embodiment shown here, as described above, even if any of the forces ± Fx, ± Fy, ± Fz in the three axes and the moments ± Mx, ± My, ± Mz around the three axes is applied, the first Therefore, even when an emergency such as a collision or a drop occurs, the thin portion can be prevented from being damaged.

  In the past, it was necessary to select the material used for the thin part in consideration of the balance between the required measurement range and the elastic deformation area of the thin part, and the robustness of the thin part. If used, you will be freed from such restrictions. That is, in the force sensor according to the present invention, the maximum displacement amount of the first substrate 100 is the gap dimensions L1 and L2 shown in FIG. 2, the inner diameter φ20 of the recesses H21 to H24, and the outer diameter φ40 of the stopper members 41 to 44. Can be set arbitrarily by setting to a desired value. Therefore, no matter what material is used for the thin portion, the allowable displacement can be set to a desired value.

<<< §4. Principle of force detection >>
The force sensor according to the present invention detects an external force acting on the first substrate 100 by electrically detecting the deformation state of the thin portion. In the case of the force sensor shown in FIG. 1, the conductive lower end side thin portions 215, 225, 235, and 245, and a total of 20 electrodes E 11 to E 45 (see FIG. 6) arranged so as to oppose them. The 20 capacitive elements C11 to C45 that are configured function as the deformation measuring units S1 to S4, and the deformation states of the lower end side thin portions 215, 225, 235, and 245 are measured. Specifically, a measurement circuit (not shown) that electrically detects the capacitance of each of the capacitive elements C11 to C45 is provided, and the detection circuit detects the capacitance value measured by the measurement circuit. The direction and magnitude of the external force acting on the first substrate 100 are detected by performing a predetermined calculation.

  As described above, a specific method for detecting the direction and magnitude of the external force applied to the first substrate 100 based on the capacitance value of each capacitive element, and a specific configuration example of the detection circuit are described above. This is a known technique disclosed in Patent Documents 7 and 8 and the like. According to this known technique, all of the forces ± Fx, ± Fy, ± Fz acting in the XYZ axis direction and the moments ± Mx, ± My, ± Mz acting around the XYZ axis can be detected independently. It becomes possible.

  Specifically, for example, as shown in FIG. 7, when a force + Fz in the positive direction of the Z-axis is applied, the capacitance value of each of the 20 capacitive elements C11 to C45 is small because the electrode interval is widened. . On the other hand, as shown in FIG. 8, when the force -Fz in the negative direction of the Z-axis is applied, the capacitance value of each of the 20 capacitive elements C11 to C45 is increased because the electrode interval is reduced. Therefore, for example, if the capacitance values measured for the capacitive elements C11 to C45 are indicated by the same symbols C11 to C45, the force Fz in the Z-axis direction is obtained by the calculation Fz = − (C15 + C25 + C35 + C45). be able to.

  On the other hand, as shown in FIG. 10, when a force + Fx in the X-axis positive direction is applied, the capacitance elements C11, C21, C31, and C41 all have a small capacitance between the electrodes, so that the capacitance value increases. In C12, C22, C32, and C42, since the electrode interval is wide, the capacitance value is small. When the force -Fx in the negative X-axis direction is applied, the reverse phenomenon occurs. Therefore, the force Fx in the X-axis direction can be obtained, for example, by a calculation of Fx = (C11 + C21 + C31 + C41) − (C12 + C22 + C32 + C42). Similarly, the force Fy in the Y-axis direction can be obtained, for example, by a calculation of Fy = (C13 + C23 + C33 + C43) − (C14 + C24 + C34 + C44).

  Further, as shown in FIG. 9, when the moment + My around the Y-axis positive direction is applied, all of the five capacitive elements C11 to C15 have a large capacitance value because the electrode interval becomes narrow. The capacitive elements C21 to C25 all have a large capacitance between electrodes, so that the capacitance value becomes small. When the reverse rotation moment -My acts, the reverse phenomenon occurs. Therefore, the moment My around the Y-axis can be obtained by, for example, the calculation My = (C11 + C12 + C13 + C14 + C15) − (C21 + C22 + C23 + C24 + C25). Similarly, the moment Mx around the X axis can be obtained by, for example, the calculation of Mx = (C41 + C42 + C43 + C44 + C45) − (C31 + C32 + C33 + C34 + C35).

  Furthermore, as shown in FIG. 12, when a moment + Mz around the positive direction of the Z-axis is applied, the capacitance elements C13, C24, C32, and C41 all have a small capacitance between the electrodes, so that the capacitance value increases. All of the elements C14, C23, C31, and C42 have a large electrode interval, so that the capacitance value becomes small. When the reverse rotation moment -Mz is applied, the reverse phenomenon occurs. Therefore, the moment Mz around the Z-axis can be obtained, for example, by an operation of Mz = (C13 + C24 + C32 + C41) − (C14 + C23 + C31 + C42).

  Thus, the force sensor shown in FIG. 1 independently detects all of the forces ± Fx, ± Fy, ± Fz acting in the XYZ axis directions and the moments ± Mx, ± My, ± Mz acting around the XYZ axes. It becomes possible to do. However, the detection method described above is only an example, and various other detection methods can be applied. Since these various detection methods are disclosed in the above-mentioned Patent Documents 7 and 8, etc., detailed description thereof is omitted here. Japanese Patent Application No. 2008-108855 proposes a more accurate detection method that eliminates interference of other axis components, and can also be applied to a force sensor according to the present invention.

  In the embodiment shown in FIG. 1, the deformation measurement unit measures the deformation state of the lower end side thin portions 215, 225, 235, and 245, but measures the deformation state of the upper end side thin portions 115, 125, 135, and 145. Thus, the applied external force can be detected.

  The present invention is a technique relating to displacement control for preventing damage to a thin portion when an excessive force is applied to a force sensor having the thin portion. Therefore, the specific method for detecting the deformation state of the thin part is not the essential part of the present invention, and the deformation measuring part has a function of electrically detecting the deformation state of any thin part. You can use whatever you want.

  For example, in the above-mentioned Patent Documents 3 and 4, a piezoresistive element is arranged at a predetermined position of the thin part, and the mechanical expansion and contraction of the individual parts of the thin part based on the change in electric resistance of each piezoresistive element. A technique for grasping the state is disclosed. In the present invention, such a piezoresistive element can also be used as a deformation measuring unit. In that case, the thin part is made of an insulating material, and a piezoresistive element is arranged on the surface of the thin part (or may be embedded inside), and a piezoresistive element is used by using a bridge circuit or the like. What is necessary is just to detect the change of resistance and to electrically detect the deformation state of the thin portion.

  Moreover, the above-mentioned Patent Documents 5 and 6 disclose techniques for detecting the displacement of each portion of the thin portion based on the electric charge generated in the piezoelectric element. In the present invention, such a piezoelectric element can be used as a deformation measuring unit. In this case, if the piezoelectric element is arranged at a predetermined position where stress is generated according to the deformation of the thin part, and the electric charge generated in each piezoelectric element is measured, the deformation state of the thin part is electrically detected. Good.

  Further, in the embodiment shown in FIG. 1, the upper end side thin portion is provided at four locations on the first substrate 100 side, and the lower end side thin portion is provided at four locations on the second substrate 200 side to connect the two. For this purpose, four columnar bodies T1 to T4 are provided. However, in carrying out the present invention, it is sufficient that the upper end side thin portion and the lower end side thin portion are provided at a plurality of locations, respectively. It is not necessary to have it. Similarly, the number of columnar bodies is not necessarily limited to four, and a plurality of columnar bodies may be provided.

  In the embodiment shown in FIG. 1, since the displacement control is performed using the four locking pins 51 to 54, the recesses and the through holes are provided in four places, but the number of the locking pins is four. The arrangement is not limited to the book, and the arrangement may be arbitrary. For example, three locking pins may be arranged at a central angle of 120 ° along the circumference, or six locking pins are arranged at a central angle of 60 ° along the circumference. You may make it do. Alternatively, three or more locking pins may be arranged side by side on a straight line.

  In the embodiments described so far, the shape of the through hole, the concave portion, the support member, and the stopper member is a cylindrical shape. However, it is not always necessary to use a cylindrical shape. It may be a columnar shape or any other arbitrary shape. “Diameter” as used in the present application does not mean only the radius or diameter of a circle, but the length of “I am” in a certain direction. Therefore, when the shape of the through hole, recess, strut member, and stopper member is an arbitrary shape, the “diameter” in each direction targeted for displacement control satisfies the dimensional condition of φ30 <φ10 <φ40 <φ20. Just do it.

It is a sectional side view which shows the state which cut | disconnected the force sensor which concerns on fundamental embodiment of this invention along XZ plane. It is an expanded sectional side view of the upper right part of the force sensor shown in FIG. It is a sectional side view which shows the state which decomposed | disassembled the force sensor shown in FIG. 1 into each component. FIG. 4 is a top view of the first substrate 100 shown in FIG. 3. FIG. 4 is a top view of the second substrate 200 shown in FIG. 3. FIG. 4 is a top view of a third substrate 300 shown in FIG. 3. FIG. 3 is a side sectional view showing displacement control when a force + Fz in the positive direction of the Z-axis acts on the force sensor shown in FIG. 1. FIG. 3 is a side sectional view showing displacement control when a force −Fz in a negative Z-axis direction acts on the force sensor shown in FIG. 1. FIG. 3 is a side sectional view showing displacement control when a moment + My around the positive direction of the Y-axis acts on the force sensor shown in FIG. 1. It is a sectional side view which shows displacement control when force + Fx of the X-axis positive direction acts on the force sensor shown in FIG. It is a top view which shows displacement control when force + Fx of the X-axis positive direction acts on the force sensor shown in FIG. It is a top view which shows the displacement control when the moment + Mz around the Z-axis positive direction acts on the force sensor shown in FIG.

Explanation of symbols

31-34: support members 41-44: stopper members 51-54: locking pin 100: first substrate 110: upper columnar projection 115: upper end thin portion 120: upper columnar protrusion 125: upper end thin portion 130 : Upper columnar protrusion 135: Upper columnar thin part 140: Upper columnar protrusion 145: Upper columnar thin part 200: Second substrate 210: Lower columnar protrusion 215: Lower columnar thin part 220: Lower columnar protrusion 225: Lower end Side thin portion 230: lower columnar protrusion 235: lower end thin portion 240: lower columnar protrusion 245: lower end thin portion 300: third substrate C11 to C45: capacitance elements E11 to E45 of capacitance elements / capacitance elements : Electrode + Fx: Force in the positive direction of the X axis + Fz: Force in the positive direction of the Z axis-Fz: Force in the negative direction of the Z axis + My: Moment about the positive direction of the Y axis + Mz: Moment H about the positive direction of the Z axis 1 to H14: recessed portions H21 to H24: through holes L1, L2: gap size O: origin of coordinate system S1 to S4: deformation measuring portions T1 to T4: columnar bodies X, Y, Z: coordinate axis φ10 of three-dimensional orthogonal coordinate system : Inner diameter φ20 of through holes H11 to H14: Inner diameter φ30 of recesses H21 to H24: Outer diameter of support members 31 to 34 φ40: Outer diameter of stopper members 41 to 44

Claims (5)

A first substrate in which a flexible upper end side thin portion is formed in each of a plurality of locations;
The first substrate is disposed so as to oppose the first substrate at a predetermined interval, and a flexible lower end side thin portion is formed at a position facing the upper end side thin portion. Two substrates;
A plurality of columnar bodies that mutually connect the lower surface of the upper end side thin portion and the upper surface of the lower end side thin portion with respect to the upper end side thin portion and the lower end side thin portion at positions facing each other,
When an external force is applied to the first substrate in a state where the second substrate is fixed, the deformation state of each lower end side thin portion or each upper end side thin portion is electrically measured by this external force. A deformation measuring unit;
A detection circuit for detecting the direction and magnitude of the external force based on the measurement result of the deformation measurement unit;
With
A predetermined portion of the peripheral portion of the first substrate is dug to a predetermined depth from the upper surface side, and a recess having a predetermined diameter is formed,
The bottom surface of the recess has a diameter smaller than the diameter of the recess, and a through-hole penetrating to the lower surface of the first substrate is formed,
A locking pin having a lower end fixed to the upper surface of the second substrate is inserted through the through hole,
The locking pin is "a column member that extends upward from the upper surface of the second substrate, has an upper end protruding upward by a predetermined dimension from the bottom surface of the recess, and has a diameter smaller than the diameter of the through hole", A force sensor having a stopper member connected to an upper end of the support member and having a diameter larger than the diameter of the through hole and smaller than the diameter of the recess. The force sensor according to claim 1,
The columnar body is composed of an integral structure of the same material as the upper end side thin part, and is composed of an integral structure of the same material as the lower end side thin part, A force sensor comprising: a lower columnar protrusion extending upward from the side thin portion. The force sensor according to claim 1 or 2,
A third substrate bonded to the lower surface of the second substrate;
The thin portion on the lower end side is made of a conductive material and is disposed above the lower surface of the second substrate by a predetermined dimension so as to ensure a predetermined space between the upper surface of the third substrate. And
A plurality of electrodes are formed on a portion of the upper surface of the third substrate facing the lower-end thin portion,
The deformation measuring unit measures a deformation state of the lower end side thin portion by electrically detecting capacitance between the lower end side thin portion and each of the plurality of electrodes. Sense sensor. The force sensor according to any one of claims 1 to 3,
The through hole is formed of a cylindrical cavity having an inner diameter φ10, the concave portion is formed of a cylindrical cavity having an inner diameter φ20, the support member is formed of a cylindrical member having an outer diameter φ30, and the stopper member is an outer diameter It consists of a cylindrical member with φ40,
In a state where no external force is applied to the first substrate, the concentric arrangement is made such that the central axes of the respective cylinders constituting the through hole, the concave portion, the column member, and the stopper member coincide with each other, and φ30 <φ10 <φ40 <φ20. Force sensor characterized by being set. The force sensor according to any one of claims 1 to 4,
When two arrangement axes orthogonal to each other at the center point and a circle with a radius r centered on the center point are defined on the upper surface of the second substrate, the circle and the two arrangement axes are Four strut members are arranged at the four intersecting points, and stopper members are respectively fixed to the upper ends of the strut members.
The force sensor according to claim 1, wherein the first substrate is provided with through-holes and recesses at four locations suitable for inserting the four support members.