Force sensing device, force sensing method and equipment

Abstract

A force sensing device comprises a rigid structure (10) and force sensors (R1, R2, R3, R4), wherein the rigid structure (10) comprises rigid blocks (11) arranged at intervals, a strain amplification area (12) is formed between two adjacent rigid blocks (11), four force sensors (R1, R2, R3, R4) are grouped in two, the two groups of force sensors are selectively arranged correspondingly on two mounting surfaces of the strain amplification area (12), and the four force sensors (R1, R2, R3, R4) are connected to form different bridge circuits. When in use, the rigid structure (10) is attached to a measured object, and different bridge circuits are electrically connected to a signal processing circuit, thereby respectively detecting the deformation of the rigid structure (10) in different directions and obtaining the force acting on the measured object in the corresponding direction. The force sensing device is an integrated structure, easy to install, simple in circuit, and low in cost. The force sensing device, the force sensing method, and the equipment having the force sensing device can very sensitively detect the tiny deformation of the measured object in multi-dimensional directions and accurately identify the pressure.

Description

Technical Field

[0001] The present application belongs to the field of pressure sensing technology, and relates to a force sensing device, a force sensing method using the force sensing device, and a device having the force sensing device. Background Art

[0002] There are many pressure sensing technologies in the field of pressure sensing. These technologies use different types of sensors, combined with specific structures and circuits, to detect deformation of the measured object to a certain extent. Currently, the common ones include resistance strain gauges, pressure capacitor technology, pressure inductor technology, piezoelectric ceramic technology, MEMS (micro-electromechanical system) pressure sensor technology, etc. In addition to the complex structure and installation, these technologies also have disadvantages such as low sensitivity, low drop resistance and easy false touch. Moreover, they can only accurately detect deformation in one-dimensional direction, and the reliability of pressure detection is not high. Summary of the invention

[0003] One of the purposes of the embodiments of the present application is to provide a force sensing device, a force sensing method and an apparatus to solve the technical problems that the existing pressure sensing technology structure is complex to install or can only accurately detect deformation in one-dimensional direction.

[0004] In order to solve the above technical problems, the technical solution adopted in the embodiment of the present application is:

[0005] In a first aspect, a force sensing device is provided, comprising:

[0006] A rigid structure for fitting with the object to be measured and following the deformation of the object to be measured, comprising rigid blocks arranged at intervals along the X-axis, a strain amplification area formed between two adjacent rigid blocks, and four mounting surfaces formed around the strain amplification area; and

[0007] A plurality of force sensors are arranged in the strain amplification area, wherein every two of the four force sensors are grouped together, and two groups of the force sensors are selectively arranged correspondingly on two of the mounting surfaces. The four force sensors are connected to form different bridge circuits, and the different bridge circuits are electrically connected to the signal processing circuit to respectively detect the deformation of the rigid structure in different directions and derive the force in the corresponding direction of the measured object.

[0008] In a second aspect, a force sensing method is provided, which uses the above-mentioned force sensing device and includes the following steps:

[0009] Fitting the rigid structure onto the object to be measured;

[0010] The four force sensors in the same strain amplification zone are connected to form different bridge circuits, and the different bridge circuits are electrically connected to a signal processing circuit to respectively detect the deformation of the rigid structure in different directions and obtain the force in the corresponding direction of the measured object.

[0011] In a third aspect, a device is provided, comprising an object to be measured and the force sensing device described above, wherein the rigid structure is attached to the object to be measured.

[0012] The beneficial effects of the force sensing device, force sensing method and equipment provided by the embodiments of the present application are: the rigid structure includes rigid blocks arranged at intervals, a strain amplification area is formed between two adjacent rigid blocks, four force sensors are grouped in two, and the two groups of force sensors are selectively arranged corresponding to two of the mounting surfaces in the strain amplification area, and the four force sensors are connected to form different bridge circuits. When in use, the rigid structure is attached to the object to be measured, and different bridge circuits are electrically connected to the signal processing circuit, thereby respectively detecting the deformation of the rigid structure in different directions and deriving the force in the corresponding direction of the object to be measured. The force sensing device is an integrated structure, easy to install, simple circuit and low cost. The force sensing device, force sensing method and equipment with the force sensing device can very sensitively detect tiny deformations of the object to be measured in multi-dimensional directions, accurately identify pressure, and meet performance indicators such as no false touch, high sensitivity, high anti-drop coefficient, and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the group of embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 A schematic diagram of the assembly of a force sensing device provided in an embodiment of the present application;

[0015] Figure 2 for Figure 1 A front view of a force sensing device;

[0016] Figure 3 A three-dimensional structural diagram of a force sensing device provided in an embodiment of the present application;

[0017] Figure 4 for Figure 3 A schematic diagram of a force sensor used in a force sensing device;

[0018] Figure 5 for Figure 3 A connection diagram of an analog switch used in a force sensing device;

[0019] Figure 6 A schematic diagram of a bridge circuit provided in an embodiment of the present application;

[0020] Figure 7 A schematic diagram of a bridge circuit provided in another embodiment of the present application;

[0021] Figure 8 A schematic diagram of a bridge circuit provided in another embodiment of the present application;

[0022] Fig. 9 A three-dimensional structural diagram of a force sensing device provided in another embodiment of the present application;

[0023] Fig.10 A three-dimensional structural diagram of a force sensing device provided in another embodiment of the present application;

[0024] Fig.11 A three-dimensional structural diagram of a force sensing device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0026] In the description of the embodiments of the present application, it needs to be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the embodiments of the present application.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying the importance of a group or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0029] See also Figures 1 to 3 , an embodiment of the present application provides a force sensing device, which includes a rigid structure 10 and force sensors R1, R2, R3, and R4. The rigid structure 10 is used to fit with the object to be measured (not shown) and follow the deformation of the object to be measured. The rigid structure 10 includes rigid blocks 11 arranged at intervals along the X-axis, and a strain amplification area 12 is formed between two adjacent rigid blocks 11. The rigid structure 10 forms four mounting surfaces 10a, 10b, 10c, and 10d around the strain amplification area 12; a number of force sensors are arranged in the strain amplification area 12, wherein every two force sensors of the four force sensors R1, R2, R3, and R4 are grouped as a group, and two groups of force sensors are selectively arranged on two of the mounting surfaces, and the four force sensors are connected to form different bridge circuits (such as Figures 6 to 8 ), different bridge circuits are electrically connected to the signal processing circuit to respectively detect the deformation of the rigid structure 10 in different directions and obtain the force acting on the object in the corresponding direction.

[0030] The rigid structure 10 includes rigid blocks 11 arranged at intervals, and a strain amplification area 12 is formed between two adjacent rigid blocks 11. Four force sensors R1, R2, R3, and R4 are grouped in two, and two groups of force sensors are selectively arranged corresponding to two mounting surfaces 10a, 10b, 10c, and 10d of the strain amplification area 12. The four force sensors are connected to form different bridge circuits. When in use, the rigid structure 10 is attached to the object to be measured, and different bridge circuits are electrically connected to the signal processing circuit, thereby respectively detecting the deformation of the rigid structure 10 in different directions and obtaining the force in the corresponding direction of the object to be measured. The force sensing device is an integrated structure, easy to install, simple circuit, low cost, can very sensitively detect the tiny deformation of the object to be measured in multi-dimensional directions, accurately identify pressure, and meet performance indicators such as no false touch, high sensitivity, high anti-drop coefficient, and high reliability.

[0031] It should be noted that the signal processing circuit is electrically connected to the bridge circuit, analyzes and processes the electrical signal of the force sensor, and converts the force analog signal into a force digital signal, which belongs to the prior art.

[0032] In another embodiment of the present application, the rigid structure 10 is attached to the surface of the object to be measured through a colloid (not shown), which is easy to assemble. When the object to be measured is subjected to a force, the rigid structure 10 deforms along with the object to be measured, the deformation of the strain amplification area 12 is amplified, and the impedance of the force sensor changes accordingly. The force sensor is electrically connected to the signal processing circuit, and then a pressure signal is generated. The direction, magnitude and position of the force can be identified by analyzing the characteristics of the pressure signal. Specifically, the colloid can be VHB, double-sided tape, 502 glue, thermosetting glue, etc., which can be selected as needed.

[0033] In another embodiment of the present application, the rigid structure 10 has a certain rigidity, the strain amplification area 12 is a hollow area, and the force sensor is arranged in the strain amplification area 12. When the object to be measured is subjected to a force, the rigid structure 10 deforms along with the object to be measured, and the deformation of the strain amplification area 12 is amplified, so that the force sensor can detect the deformation of the rigid structure 10. Specifically, the rigid structure 10 can be a steel sheet, an aluminum sheet, a glass sheet, an FR4 sheet or other composite rigid materials, which can be selected as needed.

[0034] In another embodiment of the present application, a flexible substrate 21 is provided on the two mounting surfaces of the rigid structure 10 corresponding to the two groups of force sensors, and the two groups of force sensors are respectively mounted on the corresponding flexible substrates 21. The flexible substrate 21 with the force sensors is pressed onto a discrete rigid block 11 of a certain size through a colloid 30, and four force sensors are directly opposite or adjacent to the strain amplification area 12 between two adjacent discrete rigid blocks 11 to form a force sensing device, and the structure is easy to form. Specifically, the flexible substrate 21 can be FPC (flexible circuit board), PET (high temperature resistant polyester film), PI film (polyimide film) or other flexible substrates with good flatness, which can be selected as needed.

[0035] See also Figure 1 In another embodiment of the present application, two flexible substrates 21 are formed by bending a mother substrate 20. The sensor is set on two adjacent mounting surfaces or two opposite mounting surfaces. The force sensor can be attached to a mother substrate 20, and then the center of the mother substrate 20 is folded and the two inner surfaces are bonded to the two mounting surfaces. The processing is simple and the cost is low.

[0036] In another embodiment of the present application, the flexible substrate 21 is bonded to the surface of the rigid structure 10 by a colloid 30. This structure facilitates the connection between the rigid structure 10 and the flexible substrate 21, and allows the flexible substrate 21 and the rigid structure 10 to deform along with the object being measured when the object being measured is deformed by a force. The colloid 30 can be made of epoxy film, 502 glue, thermosetting glue, silicone, etc., and can be selected as needed.

[0037] See also Figure 4 , Figure 5In another embodiment of the present application, the four force sensors R1, R2, R3, R4, the power supply terminal VCC, the ground terminal GND and the detection terminals Vp and Vn of the same bridge circuit are connected through an analog switch. This solution is easy to assemble, and the four force sensors can be connected to form different bridge circuits by using an analog switch, and the on-off switching of the bridge circuit can be controlled, which is easy to operate.

[0038] Specifically, the analog switch can be a single-pole single-throw analog switch. The single-pole single-throw analog switch has a NO terminal, a COM terminal and an IN terminal. The circuit to be short-circuited (the two ends of the four force sensors R1, R2, R3, and R4) is connected to the COM terminal and the IN terminal in a predetermined connection method, and each COM terminal is connected to the power terminal VCC, the ground terminal GND, and the detection terminals Vp and Vn, respectively, to obtain a predetermined bridge circuit. Each IN terminal is used to receive an enable signal to control the SPST.

[0039] For example, if you want to form Figure 6 The bridge circuit shown requires Figure 4 The two ends of the four force sensors R1, R2, R3, and R4 shown are referenced Figure 5 The connection method is connected to the NO terminal and COM terminal of the single-pole single-throw analog switch, and each COM terminal is connected to the power supply terminal VCC, the ground terminal GND and the detection terminals Vp and Vn respectively. When the IN terminal receives an enable signal, the corresponding NO terminal and COM terminal are connected to form a predetermined bridge circuit. When the IN terminal does not receive an enable signal, the corresponding NO terminal and COM terminal are disconnected. It can be understood that if you want to form a bridge circuit like this Figure 7 or Figure 8 The bridge circuit shown in the figure requires connecting the two ends of the four force sensors R1, R2, R3, and R4 to the NO and COM terminals of the single-pole single-throw analog switch using the corresponding connection method to obtain Figure 7 or Figure 8 The bridge circuit shown.

[0040] Specifically, the single-pole single-throw analog switch can be TS3A4751, which is a bidirectional, 4-channel, normally open (NO) single-pole single-throw (SPST) analog switch. The analog switch can be used to connect four force sensors to form different bridge circuits and control the on-off switching of the bridge circuit.

[0041] See also Figure 3 , Figures 9 to 11In another embodiment of the present application, the length directions of the force sensors R1, R2, R3, and R4 are parallel to the X-axis; the four mounting surfaces are divided into a first surface 10a and a second surface 10b spaced apart along the Z-axis, and a third surface 10c and a fourth surface 10d spaced apart along the Y-axis. The first surface 10a serves as a fitting surface with the object to be measured, and the X-axis, Y-axis, and Z-axis are perpendicular to each other. This structure is easy to assemble force sensors, and the force sensors can detect forces in different directions. Specifically, the first surface 10a and the second surface 10b of the rigid structure 10 are parallel to the XY plane, and the third surface 10c and the fourth surface 10d are parallel to the XZ plane.

[0042] See also Figure 3 In another embodiment of the present application, for the same bridge circuit, two groups of force sensors (one group is R1 and R4, and the other group is R2 and R3) are correspondingly arranged on the first surface 10a and the second surface 10b, and the planes where the two force sensors R1 and R2 arranged close to the third surface 10c are located are perpendicular to the Y axis, and the planes where the two force sensors R3 and R4 arranged close to the fourth surface 10d are located are perpendicular to the Y axis. The four force sensors are connected to form different bridge circuits, and the bridge circuits are electrically connected to the signal processing circuit. Through different signal characteristics, the forces of different dimensions felt by the measured object can be identified, thereby realizing multi-dimensional force sensing. The following is an explanation based on the embodiments of two bridge circuits.

[0043] Bridge circuit embodiment 1:

[0044] When a group of force sensors R1 and R4 arranged on the first surface 10a serve as a group of relative bridge arms, and a group of force sensors R2 and R3 arranged on the second surface 10b serve as another group of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Z axis and derive the Z axis pressure of the object being measured.

[0045] Specifically, see Figure 4 , Figure 5 , after selection through the analog switch, short a and e to VCC, b and c to Vp, f and g to Vn, d and h to GND. Figure 6 The bridge circuit shown.

[0046] Assume VCC = Ui, then:

[0047] Vp = R2Ui / (R1+R2);

[0048] Vn=R4Ui / (R3+R4);

[0049] Uo=Vp-Vn=(R2R3-R1R4)Ui / [(R1+R2)(R3+R4)]……Formula 1

[0050] By taking the derivatives of R1, R2, R3 and R4 respectively, it can be seen that Uo increases with the increase of R2 and R3, and decreases with the increase of R1 and R4.

[0051] Z-axis deformation:

[0052] Viewed from the Z-axis (up and down) direction, R1 and R4 are in the same plane, and R2 and R3 are in the same plane.

[0053] When the object under test is subjected to a force from the top to the bottom, the rigid structure 10 will bend and deform from the top to the bottom following the object under test. Affected by the curvature, the force sensors R2 and R3 will be stretched to lengthen the force sensors, and R1 and R4 will be squeezed to reduce the length of the sensors. Here, we take the force sensor whose characteristic is that the resistance increases with the lengthening as an example, so R2 and R3 will increase, and R1 and R4 will decrease. In short, when pressing from the top to the bottom, R2 and R3 will increase, and R1 and R4 will decrease. From the above conclusion, it can be seen that Uo will increase in the positive direction. Similarly, when the object under test is subjected to a force from the bottom to the top, Uo will increase in the negative direction.

[0054] Y-axis deformation:

[0055] Viewed from the Y-axis (front and back) direction, R1 and R2 are in the same plane, and R3 and R4 are in the same plane.

[0056] When the object under test is subjected to force from the front to the back, the rigid structure 10 will bend from the front to the back, R4 and R3 will be stretched in the same way to lengthen the length of the force sensor, and R1 and R2 will be squeezed in the same way to reduce the length of the force sensor, that is, R3 and R4 will increase at the same time and the increase ratio will be close, while R1 and R2 will decrease at the same time and the decrease ratio will be close, so Vp and Vn will remain basically unchanged. In short, when pressing from the front to the back, Uo = Vp-Vn will remain basically unchanged. Similarly, when the object under test is subjected to force from the back to the front, Uo will also remain basically unchanged.

[0057] Therefore, the bridge circuit embodiment 1 can identify the pressure in the Z-axis (up and down) direction on the object being measured based on the signal characteristics generated by Uo.

[0058] Bridge circuit embodiment 2:

[0059] When the two force sensors R1 and R2 arranged close to the third surface 10c serve as a set of relative bridge arms, and the two force sensors R3 and R4 arranged close to the fourth surface 10d serve as another set of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Y-axis and derive the Y-axis pressure of the object being measured.

[0060] Specifically, see Figure 4, after selection through the analog switch, short a and e to VCC, b and g to Vp, f and c to Vn, d and h to GND. Figure 7 The bridge circuit shown.

[0061] Assume VCC = Ui, then

[0062] Vp=R4Ui / (R1+R4);

[0063] Vn=R2Ui / (R3+R2);

[0064] Uo=Vp-Vn=(R3R4-R1R2)Ui / [(R1+R4)(R3+R2)]...Equation Group 2

[0065] By taking the derivatives of R1, R2, R3 and R4 respectively, it can be seen that Uo increases with the increase of R4 and R3, and decreases with the increase of R1 and R2.

[0066] Z-axis deformation:

[0067] Viewed from the Z-axis (up and down) direction, R1 and R4 are in the same plane, and R2 and R3 are in the same plane.

[0068] When the object under test is subjected to a force from top to bottom, the rigid structure 10 will bend from top to bottom accordingly, R2 and R3 will be stretched in the same manner to lengthen the length of the force sensor, and R1 and R4 will be squeezed in the same manner to reduce the length of the force sensor, that is, R2 and R3 will increase at the same time and the increase ratio will be close, while R1 and R4 will decrease at the same time and the decrease ratio will be close. Substituting the data before and after the change into Formula 2, Vp and Vn will remain basically unchanged. Therefore, when pressing from top to bottom, Uo=Vp-Vn remains basically unchanged. Similarly, when the object under test is subjected to a force from bottom to top, Uo also remains basically unchanged.

[0069] Y-axis deformation:

[0070] Viewed from the Y-axis (front and back) direction, R1 and R2 are in the same plane, and R3 and R4 are in the same plane.

[0071] When the object under test is subjected to a force from the front to the back, the rigid structure 10 will bend from the top to the bottom following the object under test. Affected by the curvature, the force sensors R3 and R4 will be stretched to lengthen the sensor, and R1 and R2 will be squeezed to reduce the sensor length. Therefore, R3 and R4 will increase, and R1 and R2 will decrease. When pressing from top to bottom, substitute the front-to-back change of R into Formula 2, and Uo=Vp-Vn will increase in the positive direction. Similarly, when the object under test is subjected to a force from the back to the front, Uo will increase in the negative direction.

[0072] Therefore, the bridge circuit embodiment 2 can identify the pressure in the Y-axis (front and back) direction based on the signal characteristics generated by Uo.

[0073] The above shows that by connecting four force sensors to form different bridge circuits, or by real-time selection of the lines through analog switches to form different bridge circuits, the forces of different dimensions felt by the object under test can be identified according to the signal, thus realizing multi-dimensional force sensing. In addition to being able to detect multi-dimensional deformation, the force sensing device also has the advantages of small temperature and humidity drift, high sensitivity, and easy installation.

[0074] See also Fig. 9 In another embodiment of the present application, for the same bridge circuit, two groups of force sensors (one group is R1, R2, and the other group is R3, R4) are correspondingly arranged on the third surface 10c and the fourth surface 10d, and the planes where the two force sensors R1, R4 arranged close to the first surface 10a are located are perpendicular to the Z axis, and the planes where the two force sensors R2, R3 arranged close to the second surface 10b are located are perpendicular to the Z axis. The four force sensors are connected to form different bridge circuits, and the bridge circuits are electrically connected to the signal processing circuit. Through different signal characteristics, the forces of different dimensions felt by the measured object can be identified, thereby realizing multi-dimensional force sensing.

[0075] The force sensors are placed on the third surface 10c and the fourth surface 10d to avoid full contact between the force sensors and the colloid on one of the surfaces, ensuring that the environmental conditions of the four force sensors are the same or very close, which is conducive to eliminating or reducing the adverse effects caused by environmental factors such as temperature, humidity, and electromagnetic interference. When the object being measured is subjected to a severe positive impact, the force sensor does not follow the object being measured to withstand the positive impact, thereby enhancing the reliability of the device. The following is an explanation of the embodiments of two bridge circuits.

[0076] Bridge circuit embodiment 3:

[0077] When the two force sensors R1 and R4 arranged close to the first surface 10a serve as a group of relative bridge arms, and the two force sensors R2 and R3 arranged close to the second surface 10b serve as another group of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Z axis and derive the Z axis pressure of the object being measured.

[0078] Specifically, for Fig. 9 The 4 force sensors shown are shown in Figure 4 , after selection through the analog switch, short a and e to VCC, b and c to Vp, f and g to Vn, d and h to GND. Figure 6 The bridge circuit shown.

[0079] Assume VCC = Ui, then:

[0080] Vp = R2Ui / (R1+R2);

[0081] Vn=R4Ui / (R3+R4);

[0082] Uo=Vp-Vn=(R2R3-R1R4)Ui / [(R1+R2)(R3+R4)]……Formula 3

[0083] By taking the derivatives of R1, R2, R3 and R4 respectively, it can be seen that Uo increases with the increase of R2 and R3, and decreases with the increase of R1 and R4.

[0084] Z-axis deformation:

[0085] Viewed from the Z-axis (up and down) direction, R1 and R4 are in the same plane, and R2 and R3 are in the same plane.

[0086] When the object under test is subjected to a force from the top to the bottom, the rigid structure 10 will bend and deform from the top to the bottom following the object under test. Affected by the curvature, the force sensors R2 and R3 will be stretched to lengthen the sensor, and R1 and R4 will be squeezed to reduce the length of the sensor. Here, a force sensor with the characteristic of increasing resistance as the length increases is taken as an example, so R2 and R3 will increase, and R1 and R4 will decrease. In short, when pressing from the top to the bottom, R2 and R3 will increase, and R1 and R4 will decrease. From the above conclusion, it can be seen that Uo will increase in the positive direction. Similarly, when the object under test is subjected to a force from the bottom to the top, Uo will increase in the negative direction.

[0087] Y-axis deformation:

[0088] Viewed from the Y-axis (front and back) direction, R1 and R2 are in the same plane, and R3 and R4 are in the same plane.

[0089] When the object to be measured is subjected to a force from the front to the back, the rigid structure 10 will bend from the front to the back, R4 and R3 will be stretched in the same manner to lengthen the length of the sensor, and R1 and R2 will be squeezed in the same manner to reduce the length of the sensor, that is, R3 and R4 will increase at the same time and the increase ratio will be close, and R1 and R2 will decrease at the same time and the decrease ratio will be close, so Vp and Vn will remain basically unchanged. In short, when pressing from the front to the back, Uo = Vp-Vn remains basically unchanged. Similarly, when the object to be measured is subjected to a force from the back to the front, Uo also remains basically unchanged.

[0090] Therefore, the bridge circuit embodiment 3 can identify the pressure in the Z-axis (up and down) direction on the object being measured based on the signal characteristics generated by Uo.

[0091] Bridge circuit embodiment 4:

[0092] When a group of force sensors R1 and R2 arranged on the third surface 10c serve as a group of relative bridge arms, and a group of force sensors R3 and R4 arranged on the fourth surface 10d serve as another group of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Y-axis and derive the Y-axis pressure of the object being measured.

[0093] Specifically, for Fig. 9 The 4 force sensors shown are shown in Figure 4 , after selection through the analog switch, short a and e to VCC, b and g to Vp, f and c to Vn, d and h to GND. Figure 7 The bridge circuit shown.

[0094] Assume VCC = Ui, then:

[0095] Vp=R4Ui / (R1+R4);

[0096] Vn=R2Ui / (R3+R2);

[0097] Uo=Vp-Vn=(R3R4-R1R2)Ui / [(R1+R4)(R3+R2)]……Equation Group 4

[0098] By taking the derivatives of R1, R2, R3 and R4 respectively, it can be seen that Uo increases with the increase of R4 and R3, and decreases with the increase of R1 and R2.

[0099] Z-axis deformation:

[0100] Viewed from the Z-axis (up and down) direction, R1 and R4 are in the same plane, and R2 and R3 are in the same plane.

[0101] When the object under test is subjected to a force from top to bottom, the rigid structure 10 will bend from top to bottom accordingly, R2 and R3 will be stretched in the same manner to lengthen the length of the force sensor, and R1 and R4 will be squeezed in the same manner to reduce the length of the force sensor, that is, R2 and R3 will increase at the same time and the increase ratio will be close, while R1 and R4 will decrease at the same time and the decrease ratio will be close. Substituting the data before and after the change into formula group 4, Vp and Vn will remain basically unchanged. Therefore, when pressing from top to bottom, Uo=Vp-Vn remains basically unchanged. Similarly, when the object under test is subjected to a force from bottom to top, Uo also remains basically unchanged.

[0102] Y-axis deformation:

[0103] Viewed from the Y-axis (front and back) direction, R1 and R2 are in the same plane, and R3 and R4 are in the same plane.

[0104] When the object under test is subjected to a force from the front to the back, the rigid structure 10 will bend from the top to the bottom following the object under test. Affected by the curvature, the force sensors R3 and R4 will be stretched to lengthen the sensor, and R1 and R2 will be squeezed to reduce the length of the force sensors. Therefore, R3 and R4 will increase, and R1 and R2 will decrease. When pressing from top to bottom, substitute the front-to-back change of R into Formula 4, and Uo=Vp-Vn will increase in the positive direction. Similarly, when the object under test is subjected to a force from the back to the front, Uo will increase in the negative direction.

[0105] Therefore, the bridge circuit embodiment 4 can identify the pressure in the Y-axis (front and back) direction based on the signal generated by Uo.

[0106] The above shows that by connecting four force sensors to form different bridge circuits, or by real-time selection of the lines through analog switches to form different bridge circuits, the forces of different dimensions felt by the object under test can be identified according to the signal, thus realizing multi-dimensional force sensing. In addition to being able to detect multi-dimensional deformation, the force sensing device also has the advantages of small temperature and humidity drift, high sensitivity, and easy installation.

[0107] See also Fig.10 In another embodiment of the present application, at least two bridge circuits are provided in the same strain amplification area 12. By connecting four force sensors to form different bridge circuits, or by real-time selection of lines by analog switches to form different bridge circuits, different signal characteristics are analyzed to identify the forces of different dimensions felt by the measured object, thereby realizing multi-dimensional force sensing.

[0108] Specifically, eight resistors, R1, R2, R3, R4, R5, R6, R7, and R8, are disposed on four mounting surfaces of the strain amplification region 12. By selecting one embodiment from bridge circuit embodiments 1 and 2, and selecting one embodiment from bridge circuit embodiments 3 and 4, and combining these two embodiments, multi-dimensional force sensing under different layouts can be obtained.

[0109] In another embodiment of the present application, adding 4 resistors in the same area can obtain a richer pressure signal, ensuring the accuracy of the test. It can also meet performance requirements when some force sensors are damaged, improving the reliability of the product. It should be pointed out that the number of sensors is not limited to 4 or 8, it can be 1 channel or multiple channels, and in addition to voltage measurement, pressure detection can also be achieved by current or resistance measurement.

[0110] See also Fig.11In another embodiment of the present application, for the same bridge circuit, two groups of force sensors (one group is R1 and R4, and the other group is R2 and R3) are correspondingly arranged on two adjacent mounting surfaces, and the plane where the two force sensors R2 and R3 arranged close to one of the mounting surfaces are located is perpendicular to the Y axis, and the plane where the two force sensors R1 and R4 arranged close to the other mounting surface are located is perpendicular to the Z axis; four force sensors are connected to form different bridge circuits, and the bridge circuits are electrically connected to the signal processing circuit, which can identify the forces of different dimensions felt by the measured object through different signal characteristics, thereby realizing multi-dimensional force sensing. The following is an example of a bridge circuit for explanation.

[0111] Bridge circuit embodiment 5:

[0112] When all the force sensors are simultaneously arranged close to the third surface 10c (or the fourth surface 10d), and the force sensors respectively located on the two mounting surfaces are spaced apart by a predetermined distance, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Z axis and obtain the Z axis pressure of the object being measured;

[0113] Specifically, by simply setting four force sensors on the first surface 10a and the third surface 10c of the rigid structure 10 and electrically connecting them, it is assumed that the components Figure 6 The bridge circuit shown.

[0114] Assume VCC = Ui, then:

[0115] Vp = R2Ui / (R1+R2);

[0116] Vn=R4Ui / (R3+R4);

[0117] Uo=Vp-Vn=(R2R3-R1R4)Ui / [(R1+R2)(R3+R4)]……Formula 5

[0118] By taking the derivatives of R1, R2, R3 and R4 respectively, it can be seen that Uo increases with the increase of R2 and R3, and decreases with the increase of R1 and R4.

[0119] Viewed from the Z-axis (up and down) direction, R1 and R4 are in the same plane, and R2 and R3 are in a nearly same plane.

[0120] When the object under test is subjected to a force from top to bottom, the rigid structure 10 will bend and deform from top to bottom following the object under test. Affected by the curvature, force sensors R2 and R3 will be stretched to lengthen the sensor, and R1 and R4 will be squeezed to reduce the length of the force sensor. Here, a force sensor with the characteristic of increasing resistance as the length increases is taken as an example, so R2 and R3 will increase, and R1 and R4 will decrease. In short, when pressing from top to bottom, R2 and R3 will increase, and R1 and R4 will decrease. From the above conclusion, it can be seen that Uo will increase in the positive direction. Similarly, when the object under test is subjected to a force from bottom to top, Uo will increase in the negative direction.

[0121] From the Y-axis direction, R1 and R4, R2 and R3 are all close to the same plane. When Y-axis deformation occurs, the impedance changes of the four force sensors are close, and Uo remains basically unchanged.

[0122] Therefore, the above-mentioned embodiment 5 can be applied to identify deformation in a certain direction, and one or more bridge circuits are added to identify Y-axis deformation. Through comprehensive judgment, multi-dimensional deformation can be identified.

[0123] It can be understood that when all force sensors are simultaneously arranged close to the first surface 10a or the second surface 10b, and the force sensors located on the two mounting surfaces are spaced at a predetermined distance, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure 10 on the Z axis and derive the Y-axis pressure of the object being measured.

[0124] See also Figure 1 In another embodiment of the present application, the force sensor is a strain sensing resistor, and the strain sensing resistor is made of at least one material selected from polycrystalline semiconductor materials, amorphous semiconductor materials, polycrystalline silicon, graphene, copper-nickel alloy, carbon nanotubes, metal fine wires, and conductor-insulator composite materials. All of the above solutions can realize pressure sensing and can be selected as needed.

[0125] See also Figures 1 to 3 In another embodiment of the present application, a force sensing method is provided, which uses the above-mentioned force sensing device and includes the following steps:

[0126] Fitting the rigid structure 10 onto the object to be measured;

[0127] The four force sensors R1, R2, R3, and R4 of the same strain amplification region 12 are connected to form different bridge circuits (such as Figures 6 to 8 ), different bridge circuits are electrically connected to the signal processing circuit to respectively detect the deformation of the rigid structure 10 in different directions and obtain the force acting on the object in the corresponding direction.

[0128] The rigid structure 10 includes rigid blocks 11 arranged at intervals, and a strain amplification area 12 is formed between two adjacent rigid blocks 11. Four force sensors R1, R2, R3, and R4 are grouped in two, and two groups of force sensors are selectively arranged corresponding to two mounting surfaces of the strain amplification area 12. The four force sensors are connected to form different bridge circuits. When in use, the rigid structure 10 is attached to the object to be measured, and different bridge circuits are electrically connected to the signal processing circuit, thereby respectively detecting the deformation of the rigid structure 10 in different directions and deriving the force in the corresponding direction of the object to be measured. The force sensing device is an integrated structure, easy to install, simple circuit, and low cost. The force sensing method can very sensitively detect the tiny deformation of the object to be measured in multi-dimensional directions, accurately identify pressure, and meet performance indicators such as no false touch, high sensitivity, high anti-drop coefficient, and high reliability.

[0129] In another embodiment of the present application, for the four force sensors R1, R2, R3, and R4 of the same bridge circuit, the forces in different directions are identified by detecting the impedance changes of the force sensors. Figure 3 Take the force sensor shown as an example:

[0130] The object being measured is subjected to the Z-axis force:

[0131] The force acts from top to bottom, R1 decreases, R2 increases, R3 increases, and R4 decreases.

[0132] The force acts from bottom to top, R1 increases, R2 decreases, R3 decreases, and R4 increases.

[0133] The object being measured is subjected to the Y-axis force:

[0134] The force is from front to back, R1 decreases, R2 decreases, R3 increases, and R4 increases.

[0135] The force is from back to front, R1 increases, R2 increases, R3 decreases, and R4 decreases.

[0136] The object under test is subjected to torsional force around the X-axis:

[0137] Viewed from left to right, if clockwise or counterclockwise twisting occurs, R1, R2, R3 and R4 all increase.

[0138] Therefore, according to the impedance change characteristics of each force sensor, combined analysis can be performed to identify the forces in different dimensions. Other embodiments are similar and will not be described in detail. Specifically, the impedance changes of each force sensor can be monitored in real time through an external circuit to identify the forces in different directions.

[0139] In another embodiment of the present application, a device is provided, including an object to be measured and the above-mentioned force sensing device, and a rigid structure 10 is attached to the object to be measured. Since the present device adopts all the technical solutions of all the above-mentioned embodiments, it also has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0140] In another embodiment of the present application, the object to be measured is a panel or a frame. Force sensing of the panel or frame is achieved. The panel or frame can be made of non-metallic materials such as glass, plastic, ceramic, etc. The panel can be a touch screen, a display or other electronic terminal with a rigid structure 10. The frame can be a frame of various electronic terminals. By connecting the force sensor to the panel or the frame, it is possible to accurately identify the size of the touch pressure, thereby expanding the application space for electronic terminals in product applications, human-computer interaction and consumer experience. Users can directly obtain accurate force levels and quantities by touching the touch screen, display or electronic terminal. After calibration, accurate force can be obtained.

[0141] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A force sensing device, characterized in that: include: A rigid structure for fitting with the object to be measured and following the deformation of the object to be measured, comprising rigid blocks arranged at intervals along the X-axis, a strain amplification area formed between two adjacent rigid blocks, and four mounting surfaces formed around the strain amplification area; and A plurality of force sensors are arranged in the strain amplification area, wherein each two of the four force sensors are used as a group, and two groups of the force sensors are selectively arranged correspondingly on two of the mounting surfaces, and the four force sensors are connected to form different bridge circuits, and different bridge circuits are electrically connected to the signal processing circuit to respectively detect the deformation of the rigid structure in different directions and obtain the force in the corresponding direction of the measured object; The length direction of the force sensor is parallel to the X-axis; the four mounting surfaces are divided into a first surface and a second surface spaced apart along the Z-axis, and a third surface and a fourth surface spaced apart along the Y-axis, the first surface is used as a fitting surface with the object to be measured, and the X-axis, the Y-axis and the Z-axis are perpendicular to each other; For the same bridge circuit, two groups of force sensors are correspondingly arranged on the first surface and the second surface, the planes where the two force sensors arranged close to the third surface are located are perpendicular to the Y axis, and the planes where the two force sensors arranged close to the fourth surface are located are perpendicular to the Y axis; when a group of force sensors arranged on the first surface serves as a group of relative bridge arms, and a group of force sensors arranged on the second surface serves as another group of relative bridge arms, the bridge circuit is electrically connected to a signal processing circuit to detect the deformation of the rigid structure on the Z axis and obtain the Z axis pressure of the object to be measured; when the two force sensors arranged close to the third surface serve as a group of relative bridge arms, and the two force sensors arranged close to the fourth surface serve as another group of relative bridge arms, the bridge circuit is electrically connected to a signal processing circuit to detect the deformation of the rigid structure on the Y axis and obtain the Y axis pressure of the object to be measured; Or, for the same bridge circuit, two groups of force sensors are correspondingly arranged on the third surface and the fourth surface, the plane where the two force sensors arranged close to the first surface are located is perpendicular to the Z axis, and the plane where the two force sensors arranged close to the second surface are located is perpendicular to the Z axis; when the two force sensors arranged close to the first surface serve as a group of relative bridge arms, and the two force sensors arranged close to the second surface serve as another group of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure on the Z axis and obtain the Z-axis pressure of the object to be measured; when a group of force sensors arranged on the third surface serves as a group of relative bridge arms, and a group of force sensors arranged on the fourth surface serves as another group of relative bridge arms, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure on the Y axis and obtain the Y-axis pressure of the object to be measured; Or, for the same bridge circuit, two groups of force sensors are correspondingly arranged on two adjacent mounting surfaces, the plane where the two force sensors arranged close to one of the mounting surfaces are located is perpendicular to the Y axis, and the plane where the two force sensors arranged close to the other mounting surface are located is perpendicular to the Z axis; when all the force sensors are arranged close to the third surface or the fourth surface at the same time, and the force sensors respectively located on the two mounting surfaces are spaced apart by a predetermined distance, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure on the Z axis and derive the Z axis pressure of the object to be measured; when all the force sensors are arranged close to the first surface or the second surface at the same time, and the force sensors respectively located on the two mounting surfaces are spaced apart by a predetermined distance, the bridge circuit is electrically connected to the signal processing circuit to detect the deformation of the rigid structure on the Z axis and derive the Y axis pressure of the object to be measured.

2. The force sensing device according to claim 1, characterized in that: Flexible substrates are provided on the two mounting surfaces of the rigid structure corresponding to the two groups of force sensors, and the two groups of force sensors are respectively mounted on the corresponding flexible substrates.

3. The force sensing device according to claim 2, characterized in that: The two flexible substrates are formed by bending a mother substrate.

4. The force sensing device according to claim 2, characterized in that: The flexible substrate is bonded to the surface of the rigid structure through colloid.

5. The force sensing device according to claim 1, characterized in that: The four force sensors, the power supply terminal, the ground terminal and the detection terminal of the same bridge circuit are connected through an analog switch.

6. The force sensing device according to claim 1, characterized in that: At least two bridge circuits are arranged in the same strain amplification region.

7. The force sensing device according to claim 1, characterized in that: The force sensor is a strain sensing resistor, and the strain sensing resistor is made of at least one material selected from polycrystalline semiconductor materials, amorphous semiconductor materials, polycrystalline silicon, graphene, copper-nickel alloy, carbon nanotubes, metal fine wires, and conductor-insulator composite materials.

8. The force sensing device according to claim 1, characterized in that: The rigid structure is a steel sheet, an aluminum sheet, a glass sheet or a FR4 sheet.

9. A force sensing method, characterized in that The force sensing device according to claim 1 is used, comprising the following steps: Fitting the rigid structure onto the object to be measured; The four force sensors in the same strain amplification zone are connected to form different bridge circuits, and the different bridge circuits are electrically connected to a signal processing circuit to respectively detect the deformation of the rigid structure in different directions and derive the force in the corresponding direction of the measured object.

10. The force sensing method according to claim 9, wherein: For the four force sensors of the same bridge circuit, the forces in different directions are identified by detecting the impedance changes of the force sensors.

11. The device, characterized in that It comprises an object to be measured and the force sensing device as claimed in claim 1, wherein the rigid structure is attached to the object to be measured.

Images