WO2002061382A1

WO2002061382A1 - A capacitive force-sensing transducer with a deformable support

Info

Publication number: WO2002061382A1
Application number: PCT/CN2001/001538
Authority: WO
Inventors: Geng Hu
Original assignee: Geng Hu
Priority date: 2000-11-08
Filing date: 2001-11-07
Publication date: 2002-08-08
Also published as: CN1471633A; CN1288152A

Abstract

The present invention relates to a capacitive force-sensing transducer with a deformable support. The transducer comprises paired nondeformable support, paired capacitive electrode plates and a deformable support. The ends of each paired nondeformable supports are fixed on the middle portion of the deformable support parallelly, capacitive electrode plates are set oppositing each other, and are flat plates or curved surface plates/spherical surface plates having the same curvature radius one bigger another one smaller, and wherein the curved surface plates/spherical surface plates are one concave another one convex, and the capacitive electrode plates are made of insulating material, and conductive then A1 films are disposed on the opposited surfaces. The said deformable support is rod-shaped, tube-shaped or slab-shaped. The said nondeformable supports are rod-shaped, tube-shaped or slab-shaped. A force-transmitting plate is disposed on the end surface of one end of the deformable support, or two force-transmitting plates are disposed on the end surfaces of both ends of the deformable support. The transducer also comprises a annular electrode, this annular electrode is mantled concentrically at the outside of the force-transmitting plate or the outside of the radial nondeformable support. The configuration according to the present invention is simple, and the measuring error of the deformable support dueing to the appended bending is corrected, while being able to maintain the hifh sensitivity, thereby the repeatable accuracy thereof is improved.

Description

Capacitive force-sensitive sensor with deformable bracket Field of the invention

The invention belongs to the field of physical measuring instruments, and particularly relates to a capacitive force-sensitive sensor with a deformable support.

Background technique

At present, there are many types of capacitive force-sensitive sensors. For example, the Chinese patent application number is 93118056.2. Its structure is shown in Figure 1. In the figure, 101 is a deformable bracket, 102 is a radial non-deformable bracket, 103 is an axial non-deformable bracket, 104 is a movable capacitor plate, 105 is a thin conductive aluminum layer, 106 is a bonding material, and 107 is a cover plate. 108 is a thin conductive aluminum layer. The thin conductive layer 108 constitutes the fixed plate of the sensing capacitor, which is located at one end of the deformable support of the sensor. The radial non-deformable stent 102 is disc-shaped or strip-shaped, and is fixed on the inner wall of the cylindrical deformable stent 101-end, and one end of the axial non-deformable stent 103 coaxial with the deformable stent 101 is fixed in the radial direction. On the non-deformable bracket 102, a movable capacitor plate 104 is fixed on the other end thereof. A side of the movable capacitor plate 104 which is not in contact with the axially non-deformable bracket 103 is plated with a conductive thin aluminum layer 105, which is in contact with the conductive thin aluminum. Layer 108 forms a sensing capacitor. The external force acts on the deformable support along the axis direction to change the distance between the capacitor plates to realize the sensing function. However, in actual application, due to the factors of mechanical force transmission, the direction and position of the same external force each time on the sensor's deformable support are slightly different, resulting in each action of the movable plate under the same external force. The situation is slightly different. Because the radial non-deformable bracket 102 is fixed to one end of the deformable bracket 101, and the conductive thin aluminum layer 108 is fixed to the other end of the deformable bracket 101, the two capacitor plates can be used to deform the deformable bracket 101. The small differences in each deformation of the sensor are very sensitive and affect the repeatability of the sensor. If the point of application of the external force changes each time, the repeat accuracy will be worse. Summary of the Invention

The purpose of the present invention is to overcome the shortcomings of the existing force-sensitive sensors, and provide a capacitive force-sensitive sensor with a deformable bracket. The force-sensitive sensor with a new structure can maintain high sensitivity while correcting deformability. The measurement error caused by the additional bending of the stent improves its repeatability, and the structure is simple, which facilitates the use of mature technology, high-volume, and highly consistent production.

The embodiments of the present invention are as follows:

The capacitive force-sensitive sensor with a deformable bracket provided by the present invention includes a pair of non-deformable brackets 2, a pair of capacitive plates 4 and a deformable bracket 1, which are characterized in that the pair of One end of the deformable bracket 2 is respectively fixed to the middle part of the deformable bracket 1 and a capacitor plate 4 is respectively fixed to the end surface of the other end. The pair of capacitor plates 4 are placed opposite to each other and made of an insulating material, and the opposite surfaces are provided with There is a thin conductive aluminum layer; the pair of oppositely disposed capacitor plates 4 are flat plates or large and small with the same curvature radius And one convex and one concave curved panel / spherical panel; the deformable bracket 1 is rod-shaped, tubular or sheet-shaped; the non-deformable bracket 2 is rod-shaped, tubular or sheet-shaped; the deformable bracket ( 1) One end face or both end faces are provided with a force transmitting plate (11) for bearing external force; the outer side of the force transmitting plate (11) is sleeved with a concentric ring electrode (12); the ring electrode (12) can also be sleeved Outside the radial non-deformable bracket (2) and concentric therewith; the insulating material used to make the capacitor plate 4 is glass, ceramic material or plastic. The capacitive force with the deformable bracket of the present invention The sensitive sensors can be combined in a rotationally symmetrical arrangement or a parallel symmetrical arrangement to form a composite whole.

The capacitive force-sensitive sensor with a deformable bracket provided by the present invention, because the deformable bracket 1 is rod-shaped, tubular, or sheet-shaped, can facilitate low-cost, large-volume production of products with high consistency; The irregular bending of the deformable stent caused by the intermediate irregular bending moment mainly occurs near the point of action of the end force. Therefore, in the present invention, the deformable stent is located in the middle of the deformable stent to avoid this area and reduce such irregularities. The effect of regular bending increases the repeat accuracy. In order to further improve the resistance of the sensor to the irregular bending of the deformable bracket, the present invention adopts the following three measures −

1. The sensors of all the inventions are symmetrically assembled into a whole, so that the external force action line passes through the entire center line of the sensor, thereby greatly improving the overall bending strength of the sensor to further reduce the influence of irregular bending moments.

2. The two capacitor plates are one large, one small, one convex and one concave. In this way, the small displacement along the radial arc caused by the irregular bending of the deformable bracket between the capacitor plates will not significantly change the transmission. Capacitive capacitance.

3. Set up an additional ring electrode. It forms another sensing capacitor with the invariant round bracket or force transmission plate of the invented sensor. By measuring this capacitance, the bending condition of the sensor under the action of the additional irregular bending moment can be known, and the measurement result can be corrected. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a prior art;

Figures 2, 3, 4, 5, 6, 7, 8, and 9 are respectively eight embodiments of the present invention;

FIG. 10 is a schematic structural diagram of a capacitor plate 4 with a convex surface;

FIG. 11 shows a schematic diagram of a capacitor plate 4 superimposed on a mold 51 with an epoxy resin layer 121 in the middle; FIG. 12 is a schematic diagram of the structure of two capacitor plates 4 with concave or convex surfaces, respectively;

Of which: deformable bracket 1 non-deformable bracket 2

Capacitor plate 4 Conductive thin aluminum layer 6

Mould 51 Power hole 10

Epoxy resin layer 121 Power transmission plate 11

Ring electrode 12 External force F Wafer 9

Implementation

The invention is further described below with reference to the drawings and embodiments.

Example 1:

Fig. 2 is a first embodiment of the present invention. In the figure, 1 is a rod-shaped deformable bracket, 2 is a tubular non-deformable bracket, 4 is a capacitor plate, which is made of glass or ceramic insulation material, 6 is a conductive thin aluminum layer on the opposite surface of the capacitor plate 4, and is bonded The material is epoxy resin or low-melting glass; one end of a pair of tubular non-deformable brackets 2 is fixedly sleeved in the middle of the rod-shaped deformable bracket 1, and both ends of the rod-shaped deformable bracket 1 protrude from the tubular non-deformable bracket 2-a suitable section Length, and fixed it with a spot welding machine, the pair of tubular non-deformable brackets 2 are respectively bonded to a capacitor plate 4 with an adhesive material, the capacitor plate 4 has a conductive thin aluminum layer 6 on the opposite surface; The capacitor plates 4 are placed opposite to each other, one large and one small, one convex and one concave, and their curvature radii are the same.

When in use, an external force F is applied to both ends of the deformable stent 1, F of this embodiment stretches the deformable stent 1 outward, and the deformation (elongation) of the deformable stent 1 is added to the irregular bending moment of the non-deformable stent 2, The bending of the deformable stent 1 caused by the irregular bending moment is mainly concentrated near the point of force application; since the non-deformable stent 2 is far enough away from the stressed end of the deformable stent 1, avoiding this area means avoiding Most of the deformable stent 1 has irregular additional bending deformation. As a result of this deformation, an additional displacement occurs between the two capacitor plates 4, the track of the displacement is an arc tangent to the radial direction; in order to further overcome this additional displacement of the two capacitor plates 4 to improve its repeat accuracy, The two capacitor plates 4 are one large and one small, one convex and one concave. The curvature radius of the convex and concave is the same and equal to the radius of the above-mentioned arc. Since the parameters of each component of the sensor vary with the situation, the sensor for a specific purpose should be tested through experiments. Take an optimal curvature radius of the capacitor plate. In the case where the deformable bracket 1 protrudes far enough from the deformable bracket 2, the curvature radius can be infinite, and a flat plate-shaped capacitor plate can be used; the deformable in this embodiment can be used. The stent 1 may also be tubular, which can further improve sensitivity. Example 2:

Fig. 3 shows a second embodiment of the present invention. In the figure, the deformable stent 1 is tubular, the non-deformable stent 2 is tubular, and 3 is a radial non-deformable stent. The capacitor plate 4 is a capacitor plate with a conductive thin aluminum layer 6 on its opposite surface. The bonding material is low. Melting point glass, 11 is a force transmission plate that accepts external force, it should be thick enough so that its deformation under the action of the external force is negligible; the specific structure of this embodiment is: one end of a pair of tubular non-deformable brackets 2 The adhesive material is bonded with a capacitor plate 4 (a conductive thin aluminum layer 6 is provided on the opposite surface), and the other ends of the pair of tubular non-deformable brackets 2 are respectively welded with a flat plate-like non-deformable bracket 3 to form fixed components, Then, the component is relatively welded to the tube wall inside the tubular deformable bracket 1 in a state where the capacitor plates 4 are relatively close to each other. The two ends of the tubular deformable bracket 1 are respectively fixed with the power transmission plate 11 to form the present invention. A specific embodiment of a capacitive force-sensitive sensor with a deformable bracket; The deformable bracket 1 should have an appropriate height to ensure the sensitivity of the sensor. The proper distance between the radial non-deformable bracket 3 and the force transmission plate 11 is to ensure the repeatability of the device. With a certain degree of rigidity and sensitivity, the larger the diameter of the deformable support 1, the better its bending resistance and the higher the repeatability. In this structure, the capacitor plate 4 may even be flat; as another form of this embodiment, the axial tubular non-deformable bracket 2 may be directly fixed to the force transmission plate 11 and the tubular non-deformed bracket 2 may be fixed. The axis passes through the circle center of the force transmission plate 11. At this time, the opposite surface of the capacitor plate 4 should be convex and concave, and the radius of curvature of the unevenness should be equal to the junction of the force transmission plate 11 and the deformable bracket 1 directly affected by external force The vertical distance between the lowest point of the conductive layer of the capacitor plate 4 fixed to it. Example 3:

Fig. 4 shows a third embodiment of the present invention. In the figure, the center of the wafer 9 is provided with three partially overlapping circular holes. The thinner cross section of the outside of the circular hole actually functions as a deformable bracket, and the rest functions as a non-deformable bracket. The two capacitor plates 4 are horizontally welded to the wafer. The two pairs of tips formed by the overlapping of three circular holes at the center of 9 are provided with a conductive thin aluminum layer (not shown) on the opposite surfaces, and a force transmission is provided at the upper and lower ends of the vertical centerline of the wafer 9 Hole 10; the external force F is applied to the non-deformable bracket part of the disc 9 through the force-transmitting hole 10 to the deformable bracket part on both sides of the circular hole, which causes the distance between the two capacitor plates 4 to change, thereby realizing the sensing function

Example 4:

Referring to FIG. 5, the capacitive force-sensitive sensors with deformable brackets of the present invention are used in combination, and they can be arranged rotationally symmetrically or in parallel symmetrically; the combination shown in this embodiment (composite) The structure of the capacitive force-sensitive sensor with a deformable bracket is as follows: four (may be multiple) rod-shaped deformable brackets 1 are placed in parallel with each other, and both ends thereof are respectively fixed on the horizontal force transmission plate 11 and The axis of the force transmission plate 11 is arranged in a rotationally symmetrical manner. A pair of non-deformable brackets 2 are welded to the middle of the deformable bracket 1, and a pair of capacitor plates 4 are respectively bonded to the other end of the deformable bracket 2 with an adhesive material. The opposite surface of the electrode plate 4 is provided with a conductive thin aluminum layer (not shown in the figure); if the non-deformable support 2 is far enough from the power transmission plate 11, the uneven surface of the two capacitor electrode plates 4 may also be flat, and at this time, Can meet the requirements of its measurement accuracy.

The deformable supports of this embodiment are symmetrically arranged on the central axis, which is intended to improve the repeat measurement accuracy. Obviously, this kind of sensor can also be made by several sensors shown in Fig. 2 that are rotationally symmetrically welded or bonded to the force transmission plate 11; the bonding material can be epoxy resin or low melting glass; generally The deformable supports of the lower sensor should be parallel to each other. Example 5: FIG. 6 is a fifth embodiment of the present invention. Two ends of a plurality of rod-shaped deformable brackets 1 placed in parallel are respectively fixed on a power transmission plate 11 placed horizontally. The power transmission plate 11 should have a sufficient thickness. Non-deformable bracket; Capacitor plates 4 are fixed at the centers of the opposite inner end faces of the force transmission plate 11, respectively, and a conductive thin aluminum layer 6 is provided on the opposite concave and convex surfaces of the capacitor plate 4, while the capacitive plate 4 has no conductive thin aluminum The convex part on one side of the layer is the non-deformable stent 2, which can also be manufactured separately and then bonded to the corresponding position in the figure; as shown in the figure, the external force F is applied to the deformable stent through the uploading force plate 11. On 1, the curvature radius of the capacitor plate 4 should be equal to the distance between the lowest end of the upper capacitor plate 4 and the lower surface of the uploading force plate 11. In this way, the parallel offset of the force F relative to the center axis of the sensor will only cause the capacitor plate The rotation of 4 does not affect the change of the spacing between the capacitor plates 4, thereby ensuring the repeated measurement accuracy of the sensor. Obviously, the deformable stent 1 in this embodiment may also be tubular. Example 6:

FIG. 7 is a sixth embodiment of the present invention. Two ends of a plurality of deformable brackets 1 placed in parallel are respectively fixed on a power transmission plate 11 placed horizontally, and conductive thin aluminum on opposite surfaces of the two power transmission plates 11 Layer 6 is the two capacitor plates of the sensing capacitor and can be formed by photolithography. Example 7:

Fig. 8 shows a seventh embodiment of the present invention. In the figure, 1 is a rod-shaped deformable stent (can also be a tubular deformable stent), 2 is a rod-shaped non-deformable stent, 4 is a capacitor plate, 6 is a conductive thin aluminum layer, 11 is a disc-shaped power transmission plate, 12 Is a circular electrode; two ends of a rod-shaped deformable support 1 placed in parallel are fixed with a circular plate-shaped power transmission plate 11 placed horizontally, and one end of two rod-shaped non-deformed supports 2 placed on top and bottom are respectively fixed inside the power transmission plate 11 At the central part of the end surface, the capacitor electrode plate 4 is fixed on the other end surface. The opposite surfaces of the capacitor electrode plate 4 are concave and convex, with a conductive thin aluminum layer 6 on the outer side of the upper disc-shaped force transmission plate 11. A ring electrode 12 is sleeved, and a capacitance is also formed between the ring electrode 12 and the upper circular plate-shaped force transmission plate 11 (made of metal). Once the external force deviates from the range of the sensor support surface, the deformable bracket 1 is bent laterally and has a circular plate shape. The force transmission plate 11 moves to the ring electrode 12; then the capacitance between the two changes; by measuring this change in capacitance, the degree of lateral bending can be known, and the measurement result is corrected.

The ring electrode 12 in this embodiment may not be added to the outside of the force transmitting plate 11, but may be added to the outside of the radial non-deformable support 2, close to the force transmitting plate 11, and concentric with the radial non-deformable support 2. The lateral bending of the deformable support 1 is measured, thereby facilitating correction of the measurement result. Example 8:

Fig. 9 is an eighth embodiment of the present invention. In the figure, 11 is a force transmission plate, and the lower force transmission plate 11 located below functions as a sensor base; the characteristic of this embodiment is that the deformable support 1 is not a straight tube, it contains a thickness The two sets of straight tubes and the horizontal transition between the two straight tubes have the advantage that the sensitivity can be improved. The main deformation that occurs when an external force is applied is the horizontal transition of the deformable support. Such parts can be stamped and formed with a mold. The transition between the horizontal transition part and the vertical part of the non-deformable support 1 should be smooth to prevent measurement errors such as hysteresis and non-return to zero caused by excessive concentration of stress; the part of the vertical part close to the down force plate 11 should have sufficient length to ensure The contact between the deformable support 1 and the down force plate 11 does not affect its measurement accuracy.

In fact, in the present invention, the deformable stent may not be a straight rod or a straight tube; the advantage of using a straight tube or a straight rod as the elastic element is to facilitate consistent mass production and miniaturization, but the sensitivity is poor. If you replace the straight rod with a curved rod that bends in the radial direction, and change the straight tube into a drum shape or the shape shown in Figure 9, the sensitivity can be improved, but as the sensitivity increases, the distance between the two capacitor plates needs to be increased. In this way, in order to ensure the capacitance, the area of the capacitor plates must be increased, and the consistency of production is poor. In the end, whether a straight rod or a curved rod is used for the deformable bracket, or a curved tube is used for the straight tube. .

In the present invention, when one side of the capacitor plate 4 with the conductive thin layer 6 is a convex and concave curved surface, in order to make the two curved surfaces coincide with each other, one of them may be manufactured first, and then another capacitor plate is manufactured using it as a mold. A specific implementation step is as follows:

1. First, the conventional method of cold working glass is used to produce the capacitor plate 4 with a convex surface shown in Figure 10;

2. Manufacture the mold 51 with a concave surface as shown in FIG. 11 from general steel. Obviously, the curvature radius of the concave surface must be different from the curvature radius of the capacitor plate 4;

3. Apply a layer of release agent to the convex surface of the capacitor plate 4 and put a small amount of epoxy resin 121 in the concave surface of the mold 51; then place the capacitor plate 4 in the position shown in Figure 11 and squeeze it. Extrude the excess epoxy resin. After the epoxy resin is cured, remove the capacitor plate 4 and plate a thin conductive aluminum layer 6 on the surface of the epoxy resin. The mold 51 becomes another capacitor electrode. The plate 4 has a concave surface that coincides with the convex surface of the capacitor plate 4 (as shown in FIG. 12), which is of great significance in mass production.

The deformable bracket of the above sensor can be made of metal or non-metal elastic materials, such as spring steel, ceramic, quartz, single crystal silicon, etc. The capacitor plates are made of insulating materials, such as glass, ceramic or resin plastic, and conductive thin aluminum. The thickness of the layer is about 1000A. It is formed by vacuum evaporation. The conductive thin aluminum layer should be extended to the side of the capacitor plate in order to ultrasonically weld the leads. During the assembly process, a certain pressure is applied to the deformable bracket. , Deformable bracket (or deformable part of non-deformable bracket), After the capacitor plates are welded or bonded, the pressure is removed to form an accurate minute pole spacing. The bonding material may be epoxy resin or low melting glass.

The invention has a simple structure and easy assembly, and the components are convenient for mass production with high precision using mature technology. The tiny pitch of the sensing capacitor is easy to ensure. It will be widely used for its superior performance-cost ratio.

Claims

Rights request

1. A capacitive force-sensitive sensor with a deformable bracket, comprising a pair of non-deformable brackets (2), a pair of capacitive plates (4) and a deformable bracket (1), characterized in that: One end of the pair of non-deformable brackets (2) is respectively fixed to the middle portion of the deformable bracket (1), and a capacitor plate (4) is fixed to the end surface of the other end, respectively. The pair of capacitor plates (4) are opposite to each other. It is made of insulating material and has a conductive thin aluminum layer on the opposite surface.

2. The capacitive force-sensitive sensor with a deformable bracket according to claim 1, characterized in that the pair of oppositely disposed capacitive plates (4) are flat plates or large and small with the same curvature radius. And one convex and one concave curved panel / spherical panel.

3. The capacitive force-sensitive sensor with a deformable support according to claim 1, wherein the deformable support (1) is rod-shaped, tubular, or sheet-shaped.

4. The capacitive force-sensitive sensor with a deformable support according to claim 1, wherein the non-deformable support (2) is rod-shaped, tubular, or sheet-shaped.

5. The capacitive force-sensitive sensor with a deformable support according to claim 1, characterized in that a force-transmitting plate (1) for receiving an external force is provided on one end surface or both end surfaces of the deformable support (1) 11).

6. The capacitive force-sensitive sensor with a deformable bracket according to claim 5, further comprising a ring electrode (12), the ring electrode (12) being sleeved on the force transmission plate (11). Outside and concentric with it.

The capacitive force-sensitive sensor with a deformable support according to claim 1, further comprising a ring electrode (12), the ring electrode (12) being sleeved on the radial non-deformable support (2) ) And concentric with it.

The capacitive force-sensitive sensor with a deformable support according to claim 1, characterized in that the insulating material used to make the capacitor plate (4) is glass, ceramic material or plastic.

The capacitive force-sensitive sensor with a deformable bracket according to claim 1, wherein the capacitive force-sensitive sensor with a deformable bracket is combined in a rotationally symmetrical arrangement or a parallel symmetrical arrangement to form a composite whole.