Acceleration sensor

Abstract

An acceleration sensor (100), comprising a frame (110), a mass block (180), elastic beams (130) and varistors (140). The frame (110) has an inner space; the mass block (180) is located in the inner space; each elastic beam (130) comprises at least a first elastic section and a second elastic section, which are connected end to end, the first elastic section being arranged at an angle to the second elastic section; one end of each elastic beam (130) is fixed on the frame (110), and the other end of the elastic beam (130) is fixed to the mass block (180); and several varistors (140) are arranged on the elastic beams (130), and are grouped to form three Wheatstone bridge circuits (161, 162, 163). The elastic beams (130) are bent in multiple sections, such that the plane utilization rate is greater; the arrangement of the varistors (140) realizes the measurement of triaxial acceleration by means of the single mass block; and after the several varistors (140) are arranged on the elastic beams (130), the several varistors (140) are prone to being located in a stress concentration area, such that a corresponding relationship between a resistance value change of the varistors (140) due to stress and an acceleration change of the mass block (180) is more precise, thereby improving the sensitivity and precision of the acceleration sensor (100).

Description

Accelerometer

Technical field

[0001] The present application relates to the technical field of sensor equipment, and in particular to an acceleration sensor. [Background Technology]

[0002] Piezoresistive accelerometers are widely used due to their large measurement range and simple manufacturing and signal processing circuitry. Their operating principle is that when subjected to acceleration, the resistance of their internal piezoresistor changes, and the magnitude of the acceleration can be calculated from this change in resistance.

[0003] Among them, the three-axis piezoresistive accelerometer can measure acceleration in three axes and has more usage scenarios. Currently, the three-axis piezoresistive accelerometer is developing towards miniaturization and low cost. The reduction in size makes the sensitivity and accuracy of the three-axis piezoresistive accelerometer low, and the use effect is not ideal.

[0004] [Summary of the invention]

[0005] The main technical problem solved by the present application is to provide an acceleration sensor to improve the sensitivity and measurement accuracy of a three-axis piezoresistive acceleration sensor.

[0006] In order to solve the above technical problems, the technical solution adopted in this application is to provide an acceleration sensor, which includes: a frame, the frame having an internal space; a mass block, located in the internal space; a plurality of elastic beams, each of the elastic beams including at least a first elastic segment and a second elastic segment connected end to end, the first elastic segment and the second elastic segment being arranged at an angle; one end of the elastic beam is fixed to the frame, and the other end of the elastic beam is fixed to the mass block to suspend the mass block in the internal space; a plurality of piezoresistors are arranged on each of the elastic beams, grouped to form three Wheatstone bridge circuits to measure acceleration in three axes.

[0007] In a possible embodiment, the elastic beams are a first elastic beam, a second elastic beam, a third elastic beam and a fourth elastic beam of the same shape; the first elastic beam, the second elastic beam, the third elastic beam and the fourth elastic beam are sequentially connected to the side of the mass block; wherein, two adjacent elastic beams are axially symmetrically arranged; and two opposite elastic beams are centrally symmetrically arranged.

[0008] In a possible embodiment, each of the elastic beams includes a first elastic segment and a second elastic segment, and the first elastic segment and the second elastic segment are arranged vertically; wherein, one end of the first elastic segment is connected to the frame, and one end of the second elastic segment is connected to the mass block.

[0009] In a possible embodiment, the varistor includes a first varistor, a second varistor, a third varistor, a fourth varistor, a fifth varistor, a sixth varistor, a seventh varistor, an eighth varistor, a ninth varistor, a tenth varistor, an eleventh varistor and a twelfth varistor; wherein the fifth varistor, the ninth varistor and the first varistor are arranged on the first elastic beam; the sixth varistor, the tenth varistor and the second varistor are arranged on the second elastic beam; the seventh varistor, the eleventh varistor and the third varistor are arranged on the third elastic beam; the eighth varistor, the twelfth varistor and the fourth varistor are arranged on the fourth elastic beam.

[0010] In a possible embodiment, the first piezoresistor, the second piezoresistor, the third piezoresistor, and the fourth piezoresistor are respectively arranged on the second elastic segment of each of the elastic beams, close to one end of the mass block; the fifth piezoresistor, the sixth piezoresistor, the seventh piezoresistor, and the eighth piezoresistor are respectively arranged on the first elastic segment of each of the elastic beams, close to one end of the frame; the ninth piezoresistor, the tenth piezoresistor, the eleventh piezoresistor, and the twelfth piezoresistor are respectively arranged on the first elastic segment of each of the elastic beams, close to one end of the second elastic segment.

[0011] In a possible implementation manner, the piezoresistors on two adjacent elastic beams are symmetrically arranged; and the piezoresistors on two opposite elastic beams are centrally symmetrically arranged.

[0012] In a possible implementation, the third varistor, the fourth varistor, the fifth varistor, and the sixth varistor are first-type varistors; the first varistor, the second varistor, the seventh varistor, and the eighth varistor are second-type varistors; and the ninth varistor, the tenth varistor, the eleventh varistor, and the twelfth varistor are third-type varistors.

[0013] In a possible implementation manner, the first type of varistor, the second type of varistor, and the third type of varistor are the same.

[0014] In a possible embodiment, it also includes: a plurality of conductive leads arranged on the elastic beam, one end of each of the conductive leads is also connected to a gold finger; each of the piezoresistors is arranged on the conductive lead, and a preset circuit is formed by the conductive leads; wherein the fifth piezoresistor, the third piezoresistor, the fourth piezoresistor, and the sixth piezoresistor constitute a first Wheatstone bridge circuit to measure the acceleration in the z-axis direction; the first piezoresistor, the second piezoresistor, the seventh piezoresistor, and the eighth piezoresistor constitute a second Wheatstone bridge circuit to measure the acceleration in the x-axis direction; the eleventh piezoresistor, the ninth piezoresistor, the tenth piezoresistor, and the twelfth piezoresistor constitute a third Wheatstone bridge circuit to measure the acceleration in the y-axis direction.

[0015] In one possible implementation, the fifth varistor is connected in series with the third varistor, and the fourth varistor is connected in series with the sixth varistor; the two groups of series resistors are connected in parallel to form the first Wheatstone bridge circuit; the first varistor is connected in series with the second varistor, and the seventh varistor is connected in series with the eighth varistor; the two groups of series resistors are connected in parallel to form the second Wheatstone bridge circuit; the eleventh varistor is connected in series with the ninth varistor, and the tenth varistor is connected in series with the twelfth varistor; the two groups of series resistors are connected in parallel to form the third Wheatstone bridge circuit.

[0016] The present application has the following beneficial effects: Unlike the prior art, the present application provides an acceleration sensor comprising a frame, a mass, an elastic beam, and a piezoresistor. The frame has an internal space; the mass is located in the internal space; each elastic beam comprises at least a first elastic segment and a second elastic segment connected end to end, the first elastic segment and the second elastic segment being arranged at an angle; one end of the elastic beam is fixed to the frame, and the other end of the elastic beam is fixed to the mass, thereby suspending the mass in the internal space; and a plurality of piezoresistors are arranged on each elastic beam, grouped to form three Wheatstone bridge circuits to measure acceleration in three axes. In the acceleration sensor of the present application, the elastic beam is arranged with multiple bends. Compared with straight beams, the elastic beam has a longer equivalent length and greater planar utilization. The arrangement of the piezoresistors enables measurement of acceleration in three axes, and after the piezoresistors are arranged on the elastic beams, they are more likely to be located in stress concentration areas. This makes the correspondence between the change in resistance of the piezoresistors caused by stress and the change in acceleration of the mass more accurate, thereby improving the sensitivity and accuracy of the acceleration sensor.

[0017] The structure of the present application as well as its other objectives and beneficial effects will be described in detail with reference to the accompanying drawings to ensure that the description of the preferred embodiments is more obvious and understandable.

Brief Description of the Drawings

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] FIG1 is a schematic top view of the internal structure of the acceleration sensor of the present application;

[0020] FIG2 is a schematic diagram of the structure of a first Wheatstone bridge circuit in the acceleration sensor of FIG1 ;

[0021] FIG3 is a schematic diagram of the structure of a second Wheatstone bridge circuit in the acceleration sensor of FIG1 ;

[0022] FIG4 is a schematic diagram of the structure of a third Wheatstone bridge circuit in the acceleration sensor of FIG1 ;

[0023] FIG. 5 is a schematic diagram of a cross-sectional structure of the acceleration sensor of FIG. 1 taken along AA′.

[0024] Among them, the reference numerals in the figures are:

[0025] 100, accelerometer; 110, frame; 130, elastic beam; 131, first elastic beam; 132, second elastic beam; 133, third elastic beam; 134, fourth elastic beam; 140, piezoresistor; 141, first piezoresistor; 142, second piezoresistor; 143, third piezoresistor; 144, fourth piezoresistor; 145, fifth piezoresistor; 146, sixth piezoresistor; 147, seventh piezoresistor; 148, eighth piezoresistor varistor; 149. Ninth varistor; 1410. Tenth varistor; 1411. Eleventh varistor; 1412. Twelfth varistor; 150. Gold finger; 151. Low-resistance silicon; 161. First Wheatstone bridge circuit; 162. Second Wheatstone bridge circuit; 163. Third Wheatstone bridge circuit; 171. Conductive lead; 180. Mass block; 181. Upper cover; 182. Lower cover; 183. Limit block; 184. Bonding ring. [Specific implementation method]

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to 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 intended to limit this application.

[0027] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0028] It should 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 this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise specified.

[0030] In the following description, specific details such as specific system structures and technologies are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, and circuits are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0031] The three-axis piezoresistive accelerometer is developing towards miniaturization and low cost. As the volume is reduced, the sensitivity and accuracy of the three-axis piezoresistive accelerometer are reduced.

[0032] Based on the above problems, the present application proposes an acceleration sensor, which measures acceleration in three axes by setting up multiple sections of bent elastic beams and arranging a number of piezoresistors on the elastic beams. The piezoresistors form three Wheatstone bridge circuits, thereby improving space utilization, conforming to the development trend of miniaturization of acceleration sensors, and effectively improving the sensitivity and accuracy of the three-axis piezoresistive acceleration sensor.

[0033] An acceleration sensor provided by the present application is described in detail below with reference to the accompanying drawings and embodiments.

[0034] The present application provides an acceleration sensor. Please refer to Figures 1 to 5. Figure 1 is a schematic top view of the internal structure of the acceleration sensor of the present application; Figure 2 is a schematic diagram of the first Wheatstone bridge circuit structure of the acceleration sensor of Figure 1; Figure 3 is a schematic diagram of the second Wheatstone bridge circuit structure of the acceleration sensor of Figure 1; Figure 4 is a schematic diagram of the third Wheatstone bridge circuit structure of the acceleration sensor of Figure 1; and Figure 5 is a schematic diagram of the cross-sectional structure of the acceleration sensor of Figure 1 taken along line AA'. In a specific embodiment, the acceleration sensor 100 of the present application includes a frame 110, a mass 180, an elastic beam 130, and a piezoresistor 140.

[0035] The frame 110 has an internal space. The mass block 180 is located in the internal space. There are a number of elastic beams 130, each elastic beam 130 includes at least a first elastic section and a second elastic section connected end to end, and the first elastic section and the second elastic section are arranged at an angle. One end of the elastic beam 130 is fixed to the frame 110, and the other end of the elastic beam 130 is fixed to the mass block 180 to suspend the mass block 180 in the internal space. A number of piezoresistors 140 are arranged on each elastic beam 130 and grouped to form three Wheatstone bridge circuits to measure acceleration in three axial directions. Specifically, the frame 110 defines the internal space and plays a supporting and protective role. In order to meet the miniaturization development trend of the three-axis piezoresistive acceleration sensor 100, in this embodiment, the acceleration sensor 100 is an acceleration sensor 100 with a single mass block 180. Acceleration in all three axes is sensed by a single mass 180. When mass 180 is subjected to acceleration, it displaces, simultaneously pulling on each elastic beam 130 and causing it to deform. This deformation of elastic beam 130 causes stress on the piezoresistors 140 attached to the beams 130, resulting in a change in resistance. By measuring the change in resistance of the piezoresistors 140, the magnitude of the stress applied to them can be determined. Material mechanics analysis can then be used to determine the inertial force acting on mass 180. Finally, Newton's second law can be used to determine the magnitude of the acceleration of mass 180. For linear beams, stress concentration areas occur at the base of the two ends of the linear beam. Compared to linear beams, this embodiment employs a multi-section curved elastic beam 130. This design ensures that stress concentration areas are located not only at the ends of the elastic beam 130 but also at the bends of the beam 130. This ensures that all piezoresistors 140 attached to the elastic beam 130 are located within these stress concentration areas. At the same time, the multi-section bent elastic beam 130 has a greater space utilization rate and a longer equivalent length, which is in line with the development trend of miniaturization of the acceleration sensor 100.

[0036] Different from the prior art, the present application proposes an acceleration sensor 100, which is provided with a multi-section bent elastic beam 130. The multi-section bent elastic beam 130 has a greater space utilization rate, making it easier to set the piezoresistor 140 on the elastic beam 130 in the stress concentration area, which is in line with the miniaturization development trend of the three-axis piezoresistive acceleration sensor 100. Moreover, the piezoresistor 140 is located in the stress concentration area, and the correspondence between the resistance change of the piezoresistor 140 and the acceleration change of the mass block 180 is more accurate, thereby improving the sensitivity and accuracy of the acceleration sensor 100.

[0037] In this embodiment, each elastic beam 130 includes a first elastic segment and a second elastic segment, with the first elastic segment and the second elastic segment being arranged perpendicularly. The first elastic segment is connected to the frame 110 at one end, and the second elastic segment is connected to the mass block 180 at one end. Specifically, in this embodiment, the elastic beam 130 is arranged in two sections. The perpendicular arrangement of the first and second elastic segments increases the planar utilization of the elastic beam 130, thereby improving the sensitivity and accuracy of the acceleration sensor 100. In other embodiments, the first and second elastic segments can be arranged at non-perpendicular angles, for example, at an acute or obtuse angle. Furthermore, the elastic beam 130 can be arranged in three or four sections, or other configurations. The only requirement is that the elastic beam 130 be arranged in a multi-section curved configuration, and this is not a specific limitation.

[0038] In the present embodiment, the elastic beams 130 are a first elastic beam 131, a second elastic beam 132, a third elastic beam 133, and a fourth elastic beam 134 of identical shape. The first elastic beam 131, the second elastic beam 132, the third elastic beam 133, and the fourth elastic beam 134 are sequentially arranged around the sides of the mass 180. Two adjacent elastic beams 130 are arranged axially symmetrically, while two opposing elastic beams 130 are arranged symmetrically around the center. Specifically, the four elastic beams 130 are arranged around the mass 180, suspending the mass 180 within the interior space of the frame 110. This effectively prevents packaging or external stress from affecting the structure within the frame 110, thereby improving the stability of the acceleration sensor 100 and the accuracy of acceleration measurement. Simultaneously, in a preferred embodiment, within the frame 110, both sides of the elastic beams 130 are also surrounded by the mass 180, and the elastic beams 130 are embedded in the mass 180. This arrangement makes the stress changes in the elastic beams 130 more sensitive when the acceleration of the mass 180 changes, thereby improving measurement accuracy.

[0039] Furthermore, in this embodiment, the acceleration sensor 100 also includes an upper cover plate 181 and a lower cover plate 182. The upper cover plate 181 and the lower cover plate 182 are respectively arranged on the two sides of the frame 110 through a bonding ring 184. Specifically, the upper cover plate 181 and the lower cover plate 182 are used to seal and protect the frame 110. Among them, the upper cover plate 181 and the lower cover plate 182 also have a protrusion in the area of ​​the mass block 180 on the side facing the frame 110 to form a limit block 183. The limit block 183 limits the displacement of the mass block 180 in the z-axis direction, thereby improving the stability of the acceleration sensor 100. In some embodiments, the bonding ring 184 at one end of the upper cover plate 181 close to the gold finger 150 is connected to the low-resistance silicon 151, ensuring the flatness of the connection surface and making the connection stable.

[0040] In this embodiment, the acceleration sensor 100 is a triaxial piezoresistive accelerometer 100. The triaxial piezoresistive accelerometer 100 measures acceleration along three axes using three Wheatstone bridge circuits. Existing triaxial piezoresistive accelerometers 100 using a single mass 180 suffer from significant cross-coupling interference when measuring acceleration between the axes.

[0041] In this embodiment, acceleration-sensing units, such as the elastic beams 130 and mass 180, are arranged centrally and symmetrically within the frame 110. By configuring each elastic beam 130 to include a first elastic segment and a second elastic segment that are perpendicular to each other, mechanical decoupling between acceleration measurements on each axis is enhanced. The acceleration sensor 100 measures acceleration along each of the three axes using three Wheatstone bridge circuits. The arrangement of piezoresistors 140 on each of the multi-segmented elastic beams 130 further enhances electrical decoupling between acceleration measurements on each axis, reducing cross-coupling interference.

[0042] The arrangement of the varistor 140 in this embodiment is described below.

[0043] The triaxial piezoresistive accelerometer 100 includes three Wheatstone bridge circuits, each of which is composed of four piezoresistors 140. In this embodiment, the piezoresistors 140 include a first piezoresistor 141, a second piezoresistor 142, a third piezoresistor 143, a fourth piezoresistor 144, a fifth piezoresistor 145, a sixth piezoresistor 146, a seventh piezoresistor 147, an eighth piezoresistor 148, a ninth piezoresistor 149, a tenth piezoresistor 1410, an eleventh piezoresistor 1411, and a twelfth piezoresistor 1412; The resistor 149 and the first piezoresistor 141 are disposed on the first elastic beam 131; the sixth piezoresistor 146, the tenth piezoresistor 1410, and the second piezoresistor 142 are disposed on the second elastic beam 132; the seventh piezoresistor 147, the eleventh piezoresistor 1411, and the third piezoresistor 143 are disposed on the third elastic beam 133; and the eighth piezoresistor 148, the twelfth piezoresistor 1412, and the fourth piezoresistor 144 are disposed on the fourth elastic beam 134. Specifically, each of the twelve piezoresistors 140 has the same initial resistance value, and each piezoresistor 140 has the same linear characteristics. When subjected to the same stress, the resistance value of each piezoresistor 140 changes in the same manner.

[0044] The accelerometer 100 further includes a plurality of conductive leads 171, which are arranged on the elastic beam 130. One end of each conductive lead 171 is also connected to the gold finger 150. Each piezoresistor 140 is arranged on the conductive lead 171, and a preset circuit is formed through the conductive lead 171. The fifth piezoresistor 145, the third piezoresistor 143, the fourth piezoresistor 144, and the sixth piezoresistor 146 form a first Wheatstone bridge circuit 161 to measure acceleration in the z-axis. The first piezoresistor 141, the second piezoresistor 142, the seventh piezoresistor 147, and the eighth piezoresistor 148 form a second Wheatstone bridge circuit 162 to measure acceleration in the x-axis. The eleventh piezoresistor 1411, the ninth piezoresistor 149, the tenth piezoresistor 1410, and the twelfth piezoresistor 1412 form a third Wheatstone bridge circuit 163 to measure acceleration in the y-axis. Furthermore, low-resistance silicon 151 is fabricated at both ends of the varistor 140 , and the conductive wire 171 is connected to the low-resistance silicon 151 to achieve electrical connection of the varistor 140 .

[0045] In this embodiment, please refer to FIG. 2 to FIG. 4 for the composition of each Wheatstone bridge circuit.

[0046] The fifth varistor 145 is connected in series with the third varistor 143, and the fourth varistor 144 is connected in series with the sixth varistor 146; the two groups of series resistors are connected in parallel to form a first Wheatstone bridge circuit 161; the first varistor 141 is connected in series with the second varistor 142, and the seventh varistor 147 is connected in series with the eighth varistor 148; the two groups of series resistors are connected in parallel to form a second Wheatstone bridge circuit 162; the eleventh varistor 1411 is connected in series with the ninth varistor 149, and the tenth varistor 1410 is connected in series with the twelfth varistor 1412; the two groups of series resistors are connected in parallel to form a third Wheatstone bridge circuit 163.

[0047] Specifically, according to the first Wheatstone bridge circuit 161, Z_Vout = (R3·R4-R5·R6) / ((R3+R5)·(R4+R6))·VDD; in the above formula, Z_Vout is the output voltage of the first Wheatstone bridge circuit 161, R3 is the resistance of the third varistor 143, R4 is the resistance of the fourth varistor 144, R5 is the resistance of the fifth varistor 145, R6 is the resistance of the sixth varistor 146, and VDD is the power supply voltage. The output voltage in the z-axis direction can be calculated by the calculation formula. According to the second Wheatstone bridge circuit 162, X_Vout = (R2·R7-R1·R8) / ((R1+R7)·(R2+R8))·VDD; in the above formula, X_Vout is the output voltage of the second Wheatstone bridge circuit 162, R1 is the resistance of the first varistor 141, R2 is the resistance of the second varistor 142, R7 is the resistance of the seventh varistor 147, R8 is the resistance of the eighth varistor 148, and VDD is the supply voltage. The output voltage in the x-axis direction can be calculated using the calculation formula. According to the third Wheatstone bridge circuit 163, Y_Vout = (R9·R10-R11·R12) / ((R9+R11)·(R10+R12))·VDD; where Y_Vout is the output voltage of the third Wheatstone bridge circuit 163, R9 is the resistance of the ninth varistor 149, R10 is the resistance of the tenth varistor 1410, R11 is the resistance of the eleventh varistor 1411, R12 is the resistance of the twelfth varistor 1412, and VDD is the supply voltage. The output voltage along the y-axis can be calculated using the calculation formula.

[0048] In this embodiment, the first piezoresistor 141, the second piezoresistor 142, the third piezoresistor 143, and the fourth piezoresistor 144 are respectively arranged on the second elastic section of each elastic beam 130, close to one end of the mass block 180; the fifth piezoresistor 145, the sixth piezoresistor 146, the seventh piezoresistor 147, and the eighth piezoresistor 148 are respectively arranged on the first elastic section of each elastic beam 130, close to one end of the frame 110; the ninth piezoresistor 149, the tenth piezoresistor 1410, the eleventh piezoresistor 1411, and the twelfth piezoresistor 1412 are respectively arranged on the first elastic section of each elastic beam 130, close to one end of the second elastic section. In addition, the piezoresistors 140 on two adjacent elastic beams 130 are symmetrically arranged; the piezoresistors 140 on two opposite elastic beams 130 are centrally symmetrically arranged. Specifically, the initial resistance of each piezoresistor 144 is r. When the mass block 180 is subjected to the positive direction of the z-axis. The size is a z When the acceleration is , the stress on the varistor 140 is T z , Δr z The varistor 140 is subjected to stress T z In addition, within the z-axis acceleration measurement range, Δr z / r and a z There is an approximate linear relationship. When the mass block 180 is subjected to a positive direction of the x-axis and a x When the acceleration is , the stress on the varistor 140 is T x , Δr x The varistor 140 is subjected to stress T x In addition, within the x-axis acceleration measurement range, Δr x / r and a x There is an approximate linear relationship. When the mass block 180 is subjected to a y When the acceleration is , the stress on the varistor 140 is T y , Δr y The varistor 140 is subjected to stress T y In addition, within the y-axis acceleration measurement range, Δr y / r and a y There is an approximately linear relationship.

[0049] When the mass block 180 has accelerations in different axial directions, causing each piezoresistor 140 to be subjected to different stresses, the resulting resistance changes are shown in the following table:

[0050] Table 1

[0051] The table above shows the change in resistance of each piezoresistor 140 when subjected to positive acceleration along each axis. A + indicates an increase in resistance of the piezoresistor 140 after the stress is applied, while a - indicates a decrease in resistance of the piezoresistor 140 after the stress is applied. If the mass 180 experiences negative acceleration, the sign of the resistance change is opposite.

[0052] In this embodiment, the third varistor 143, the fourth varistor 144, the fifth varistor 145, and the sixth varistor 146 are first-type varistors; the first varistor 141, the second varistor 142, the seventh varistor 147, and the eighth varistor 148 are second-type varistors; and the ninth varistor 149, the tenth varistor 1410, the eleventh varistor 1411, and the twelfth varistor 1412 are third-type varistors. The first, second, and third-type varistors are identical.

[0053] The piezoresistors 140 are arranged symmetrically, and each piezoresistor 140 has the same initial resistance and resistance pressure change law. When the mass block 180 is subjected to a positive z-axis with a magnitude of a z When the acceleration is Δr, the resistance change of each varistor 140 is expressed as follows: z1 ≈Δr z2 ≈Δr z3 ≈Δr z4 =Δr1; Δr z5 ≈Δr z6 ≈Δr z7 ≈Δr z8 =Δr2; Δr z9 ≈Δr z10 ≈Δr z11 ≈Δr z12 =Δr3;

[0054] Combining the output voltage formulas of the first Wheatstone bridge circuit 161, the second Wheatstone bridge circuit 162, and the third Wheatstone bridge circuit 163, we can obtain: X_ Vout ≈0; Y_Vout≈0. In addition, due to the z-axis acceleration measurement range, Δr z / r and a z There is an approximately linear relationship, so the output voltage of the first Wheatstone bridge circuit 161 is linearly related to the Z-axis acceleration; the output voltages of the second Wheatstone bridge circuit 162 and the third Wheatstone bridge circuit 163 are approximately independent of the Z-axis acceleration.

[0055] When the mass block 180 is subjected to a force in the positive direction of the x-axis and a xWhen the acceleration is Δr, the resistance change of each varistor 140 is expressed as follows: x1 ≈Δr x2 ≈Δr x3 ≈Δr x4 =Δr4; Δr x5 ≈Δr x6 ≈Δr x7 ≈Δr x8 =Δr5; Δr x9 ≈Δr x10 ≈Δr x11 ≈Δr x12 =Δr6;

[0056] Combining the output voltage formulas of the first Wheatstone bridge circuit 161 , the second Wheatstone bridge circuit 162 , and the third Wheatstone bridge circuit 163 , we can obtain: Z_Vout≈0;

[0057] Y_Vout≈0; Y_Vout≈0. In addition, due to the x-axis acceleration measurement range, Δr x / r and a x There is an approximately linear relationship, so the output voltage of the second Wheatstone bridge circuit 162 is linearly related to the x-axis acceleration; the output voltages of the first Wheatstone bridge circuit 161 and the third Wheatstone bridge circuit 163 are approximately independent of the x-axis acceleration.

[0058] When the mass block 180 is subjected to a force in the positive direction of the y-axis and a y When the acceleration is Δr, the resistance change of each varistor 140 is expressed as follows: y1 ≈Δr y2 ≈Δr y3 ≈Δr y4 =Δr7; Δr y5 ≈Δr y6 ≈Δr y7 ≈Δr y8 =Δr8; Δr y9 ≈Δr y10 ≈Δr y11 ≈Δr y12 =Δr9;

[0059] Combining the output voltage formulas of the first Wheatstone bridge circuit 161 , the second Wheatstone bridge circuit 162 , and the third Wheatstone bridge circuit 163 , we can obtain: Z_Vout≈0; X_Vout≈0; In addition, due to the Y-axis acceleration measurement range, Δr y / r and a yThere is an approximately linear relationship, so the output voltage of the third Wheatstone bridge circuit 163 is linearly related to the y-axis acceleration; the output voltages of the first Wheatstone bridge circuit 161 and the second Wheatstone bridge circuit 162 are approximately independent of the y-axis acceleration.

[0060] In this embodiment, the arrangement of the piezoresistors 140 on the curved elastic beam 130 ensures that, when subjected to stress, the symmetrically distributed piezoresistors 140 exhibit the same absolute resistance change. This simplifies the output voltage formula, and the effect of cross-axial acceleration on the output voltage of the measured axial acceleration is approximately zero. The output voltage of the first Wheatstone bridge circuit 161 is only related to the z-axis acceleration; the output voltage of the second Wheatstone bridge circuit 162 is only related to the x-axis acceleration; and the output voltage of the third Wheatstone bridge circuit 163 is only related to the y-axis acceleration, resulting in very low cross-axis coupling interference. As described above, through the arrangement of the curved elastic beam 130 and the distribution of the piezoresistors 140 on the elastic beam, the first, second, and third types of piezoresistors are designed to be identical. In other embodiments, the first, second, and third types of piezoresistors can also be three different types of piezoresistors, without specific limitation.

[0061] Unlike the prior art, the present application proposes an acceleration sensor 100 equipped with a multi-section bent elastic beam 130. This multi-section bent elastic beam 130 provides greater space utilization, allowing the piezoresistors 140 on the elastic beam 130 to be located in stress concentration areas, conforming to the trend of miniaturization of triaxial piezoresistive acceleration sensors 100. Furthermore, the location of the piezoresistors 140 in the stress concentration areas allows for a more precise correspondence between the resistance change of the piezoresistors 140 and the acceleration change of the mass 180, thereby improving the sensitivity and accuracy of the acceleration sensor 100. Furthermore, by arranging the piezoresistors 140 in the above-described embodiment, the output voltages of the three Wheatstone bridges are related only to the acceleration of the respective measured axes, eliminating cross-coupling between acceleration measurements along each axis.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An acceleration sensor, comprising: a frame having an interior space; A mass block, located in the internal space; A plurality of elastic beams, each of the elastic beams at least comprising a first elastic section and a second elastic section connected end to end, the first elastic section and the second elastic section being arranged at an angle; one end of the elastic beam is fixed to the frame, and the other end of the elastic beam is fixed to the mass block, so as to suspend the mass block in the internal space; A plurality of piezoresistors are arranged on each of the elastic beams and grouped to form three Wheatstone bridge circuits to measure accelerations in three axes.

2. The acceleration sensor according to claim 1, The elastic beams are a first elastic beam, a second elastic beam, a third elastic beam and a fourth elastic beam having the same shape; The first elastic beam, the second elastic beam, the third elastic beam, and the fourth elastic beam are sequentially connected around the side surface of the mass block; in, The two adjacent elastic beams are axially symmetrically arranged; and the two opposite elastic beams are centrally symmetrically arranged.

3. The acceleration sensor according to claim 2, Each of the elastic beams comprises a first elastic section and a second elastic section, wherein the first elastic section and the second elastic section are arranged vertically; wherein, One end of the first elastic section is connected to the frame, and one end of the second elastic section is connected to the mass block.

4. The acceleration sensor according to claim 3, The varistors include a first varistor, a second varistor, a third varistor, a fourth varistor, a fifth varistor, a sixth varistor, a seventh varistor, an eighth varistor, a ninth varistor, a tenth varistor, an eleventh varistor and a twelfth varistor; in, The fifth varistor, the ninth varistor and the first varistor are arranged on the first elastic beam; the sixth varistor, the tenth varistor and the second varistor are arranged on the second elastic beam; the seventh varistor, the eleventh varistor and the third varistor are arranged on the third elastic beam; the eighth varistor, the twelfth varistor and the fourth varistor are arranged on the fourth elastic beam.

5. The acceleration sensor according to claim 4, The first varistor, the second varistor, the third varistor, the fourth varistor The sensitive resistor is respectively arranged on one end of the second elastic section of each of the elastic beams close to the mass block; The fifth varistor, the sixth varistor, the seventh varistor, and the eighth varistor are respectively arranged on one end of the first elastic section of each of the elastic beams close to the frame; The ninth varistor, the tenth varistor, the eleventh varistor, and the twelfth varistor are respectively arranged on one end of the first elastic segment of each of the elastic beams close to the second elastic segment.

6. The acceleration sensor according to claim 5, The varistors on two adjacent elastic beams are symmetrically arranged; and the varistors on two opposite elastic beams are centrally symmetrically arranged.

7. The acceleration sensor according to claim 5, The third varistor, the fourth varistor, the fifth varistor, and the sixth varistor are first-type varistors; The first varistor, the second varistor, the seventh varistor, and the eighth varistor are second-type varistors; The ninth varistor, the tenth varistor, the eleventh varistor, and the twelfth varistor are third-type varistors.

8. The acceleration sensor according to claim 7, The first type of varistor, the second type of varistor, and the third type of varistor are the same.

9. The acceleration sensor according to claim 5, further comprising: A plurality of conductive leads are arranged on the elastic beam, and one end of each conductive lead is also connected to a gold finger; Each of the varistors is arranged on the conductive lead, and a preset circuit is formed through the conductive lead; Wherein, the fifth piezoresistor, the third piezoresistor, the fourth piezoresistor, and the sixth piezoresistor form a first Wheatstone bridge circuit to measure the acceleration in the z-axis direction; The first piezoresistor, the second piezoresistor, the seventh piezoresistor, and the eighth piezoresistor form a second Wheatstone bridge circuit to measure acceleration in the x-axis direction; The eleventh piezoresistor, the ninth piezoresistor, the tenth piezoresistor, and the twelfth piezoresistor form a third Wheatstone bridge circuit to measure acceleration in the y-axis direction.

10. The acceleration sensor according to claim 9, The fifth varistor is connected in series with the third varistor, and the fourth varistor is connected in series with the sixth varistor; the two groups of series resistors are connected in parallel to form the first Wheatstone bridge circuit; The first varistor is connected in series with the second varistor, and the seventh varistor is connected in series with the eighth varistor; the two groups of series resistors are connected in parallel to form the second Wheatstone bridge circuit; The eleventh varistor is connected in series with the ninth varistor, and the tenth varistor is connected in series with the twelfth varistor; two groups of series resistors are connected in parallel to form the third Wheatstone bridge circuit.

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