High-temperature stability acceleration sensor based on PMUT and detection method

Abstract

The invention belongs to the field of acceleration sensors, and particularly relates to a PMUT-based high-temperature-stability acceleration sensor and a detection method. The acceleration sensor comprises a shell; the reflecting plate is fixed on one side in the shell through an elastic block; and the piezoelectric micro-mechanical ultrasonic transducer is fixed on one side, which is opposite to the reflecting plate, of the interior of the shell through a non-elastic block. The processing period of the acceleration sensor can be shortened, and the processing cost of the acceleration sensor is reduced; acceleration sensing can be guaranteed in a wide temperature range, and complexity of a later compensation circuit is reduced. Through the detection method, the acceleration detection result can be rapidly determined.

Description

Technical Field

[0001] The present application belongs to the field of acceleration sensors, and specifically relates to an acceleration sensor with high temperature stability based on a piezoelectric micromachined ultrasonic transducer (PMUT) and a detection method. Background Art

[0002] An acceleration sensor, also known as an accelerometer, is an electronic device that can measure acceleration force. There are many types of acceleration sensors, including capacitive, piezoresistive, inductive, strain gauge, and piezoelectric.

[0003] Existing capacitive and piezoresistive acceleration sensors often use a cantilever beam plus a mass block structure to sense acceleration. The deformation of the cantilever beam causes changes in electrical parameters such as capacitance and resistance to sense acceleration. The entire process is complex and costly, and has poor temperature stability. When the cantilever beam is exposed to temperature changes, the size of the cantilever beam will expand and contract, and the piezoresistance and inductance will change significantly, requiring complex compensation in the later circuit. Summary of the invention

[0004] Based on the problems existing in the prior art, the present invention proposes a high temperature stability acceleration sensor and detection method based on PMUT. Through the high stability of PMUT, the perception of acceleration can be guaranteed within a wide temperature range and the complexity of the subsequent compensation circuit can be reduced.

[0005] In a first aspect of the present invention, the present invention provides a PMUT-based high temperature stability acceleration sensor, comprising:

[0006] shell;

[0007] A reflector is fixed to one side of the inner part of the shell through an elastic block;

[0008] The piezoelectric micromechanical ultrasonic transducer is fixed on one side of the inner part of the housing directly facing the reflecting plate through a non-elastic block.

[0009] Furthermore, the piezoelectric micromechanical ultrasonic transducer is a single or array structure.

[0010] Furthermore, the elastic block is an array structure; the array structure of the elastic block corresponds to the array structure of the piezoelectric micromechanical ultrasonic transducer.

[0011] Furthermore, the material of the elastic block includes polyurethane adhesive, silicone rubber adhesive or acrylic adhesive.

[0012] Furthermore, the reflective plate is an array structure; the array structure of the reflective plate corresponds to the array structure of the elastic block.

[0013] Furthermore, it also includes a dedicated integrated circuit, which is fixed on a side of the inner part of the shell opposite to the reflecting plate and adjacent to the piezoelectric micromechanical ultrasonic transducer.

[0014] In a second aspect of the present invention, the present invention provides a high temperature stability acceleration detection method based on PMUT, using the high temperature stability acceleration sensor based on PMUT as described in the first aspect of the present invention, the method comprising:

[0015] The piezoelectric micromechanical ultrasonic transducer transmits a sound wave signal to the reflector;

[0016] The piezoelectric micromechanical ultrasonic transducer receives the echo signal reflected by the reflector;

[0017] The TOF time is calculated based on the time interval between the echo signal received by the piezoelectric micromechanical ultrasonic transducer and the peak value of the transmitted acoustic wave signal;

[0018] If the TOF time is inconsistent with the preset TOF time, acceleration is detected.

[0019] Beneficial effects of the present invention:

[0020] The invention can shorten the processing cycle of the acceleration sensor and reduce the processing cost of the acceleration sensor; the invention can ensure the perception of acceleration within a wide temperature range and reduce the complexity of the subsequent compensation circuit. The detection method of the invention can quickly determine the acceleration detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an acceleration sensor according to a first embodiment of the present invention;

[0022] Figure 2 is a schematic structural diagram of an acceleration sensor according to a second embodiment of the present invention;

[0023] Figure 3 is a schematic structural diagram of an acceleration sensor according to a third embodiment of the present invention;

[0024] Figure 4 is a schematic structural diagram of an acceleration sensor according to a fourth embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of an acceleration sensor according to a first embodiment of the present invention applying acceleration in a first direction;

[0026] Figure 6 is a schematic diagram of the acceleration sensor according to the first embodiment of the present invention applying acceleration in a second direction;

[0027] Figure 7The present invention provides a flow chart of a PMUT-based high temperature stability acceleration detection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Figure 1 FIG. 1 is a schematic diagram of the structure of an acceleration sensor according to an embodiment of the present invention; Figure 1 As shown, the acceleration sensor comprises:

[0030] The housing 100; the reflector 200 is fixed to one side of the housing through an elastic block 201; and the piezoelectric micromechanical ultrasonic transducer 300 is fixed to one side of the housing facing the reflector 200 through a non-elastic block 301.

[0031] In some embodiments, the housing 100 is a rectangular three-dimensional box that can be configured with a piezoelectric micromechanical ultrasonic transducer 300 and a reflective plate 200 .

[0032] In some embodiments, the reflector 200 is an acoustic material plate capable of reflecting sound waves, and the acoustic material plate has a flat and uniform reflective surface to ensure that the sound waves can be effectively reflected. Since the reflector 200 is disposed in the housing 100, and the interior of the housing 100 is usually a low-light scene, silver can be used to enhance its reflection intensity.

[0033] In some embodiments, the elastic block 201 is a physical or material block with uniform elastic properties, which can be deformed after being subjected to an external force, and return to its original shape and size after the external force is removed. When acceleration occurs, the elastic block 301 will produce a corresponding deformation, so that the distance between the reflector 200 and the piezoelectric micromechanical ultrasonic transducer 300 changes; illustratively, the material of the elastic block 201 includes polyurethane adhesive, silicone rubber adhesive or acrylate adhesive.

[0034] In some embodiments, the piezoelectric micromechanical ultrasonic transducer 300 is a MEMS (micro-electromechanical system) device that uses the forward and reverse piezoelectric effects of piezoelectric materials to vibrate a piezoelectric film, thereby transmitting or receiving an ultrasonic signal; when the piezoelectric micromechanical ultrasonic transducer 300 is used to transmit ultrasonic waves, it works as an actuator. By applying a voltage to the piezoelectric micromechanical ultrasonic transducer 300, the piezoelectric material will deform, thereby generating an ultrasonic signal. These ultrasonic signals are usually propagated in the medium within the housing 100 in the form of mechanical waves. When the piezoelectric micromechanical ultrasonic transducer 300 is used to receive ultrasonic signals, it works as a sensor. The ultrasonic signal acts on the piezoelectric film of the piezoelectric micromechanical ultrasonic transducer 300, causing the film to vibrate, and then converts the mechanical energy into electrical energy through the piezoelectric effect to generate an electrical signal.

[0035] In some embodiments, the piezoelectric micromechanical ultrasonic transducer is a single structure, and the piezoelectric micromechanical ultrasonic transducer is composed of a unified structure or assembly. In the single structure of the piezoelectric micromechanical ultrasonic transducer, all necessary functional elements, such as piezoelectric materials, electrodes, and possible supporting structures, are integrated into a compact and cooperative unit, which makes it easier to miniaturize and integrate the piezoelectric micromechanical ultrasonic transducer, thereby meeting the compactness and lightweight requirements of certain specific application fields.

[0036] It should be noted that the piezoelectric micromechanical ultrasonic transducer 300 has a multi-layer film structure (SiO2, etc.), and its frequency has temperature stability, so the acceleration sensing value can be stable within a wide temperature range.

[0037] The piezoelectric micromechanical ultrasonic transducer 300 has high sensitivity, which means that the piezoelectric micromechanical ultrasonic transducer 300 can generate and receive ultrasonic signals more effectively, which also makes the acceleration sensor of the present invention have high temperature stability.

[0038] In some embodiments, the inelastic block 301 is a physical or material block without elastic properties; when acceleration occurs, the inelastic block 301 will not be deformed and will not affect the distance between the piezoelectric micromechanical ultrasonic transducer 300 and the housing 100. Exemplarily, the inelastic block 301 can be made of a variety of materials, including metal, ceramic, glass, certain plastics, etc. The inelastic properties of these materials may be derived from their internal structure, chemical bonds or physical properties.

[0039] Figure 2 FIG. 1 is a schematic diagram of the structure of an acceleration sensor according to an embodiment of the present invention; Figure 2 As shown, the acceleration sensor comprises:

[0040] A shell 110; a reflector 210, fixed to one side of the shell interior via an elastic block array 211; a piezoelectric micromechanical ultrasonic transducer array 310 and a piezoelectric micromechanical ultrasonic transducer substrate 312, wherein the piezoelectric micromechanical ultrasonic transducer substrate 312 carries the piezoelectric micromechanical ultrasonic transducer array 310 and together constitutes a piezoelectric micromechanical ultrasonic transducer array structure, which is fixed to one side of the shell interior opposite to the reflector 210 via a non-elastic block 311.

[0041] In this embodiment, the piezoelectric micromechanical ultrasonic transducer array structure has multiple piezoelectric micromechanical ultrasonic transducer arrays 310, and the elastic block array 211 is an array structure of a corresponding number, so that multi-axis acceleration sensing detection can be achieved. When acceleration in any angle direction occurs, such as at an inclined angle, the degree of external force applied to the elastic block array 211 at each location is not exactly the same, which may cause different degrees of deformation of each elastic block array 211, and thus cause different distances between the reflector 210 and the corresponding piezoelectric micromechanical ultrasonic transducer array 310; and through the design of the array structure, this embodiment can better detect the distance between each piezoelectric micromechanical ultrasonic transducer array 310 and the reflector 210, and the direction and magnitude of the acceleration can be more accurately judged through this distance.

[0042] Figure 3 FIG. 1 is a schematic diagram of the structure of an acceleration sensor according to an embodiment of the present invention; Figure 3 As shown, the acceleration sensor comprises:

[0043] A housing 120; a reflector plate array 220, fixed to one side of the housing interior via an elastic block array 221; a piezoelectric micromechanical ultrasonic transducer array 320 and a piezoelectric micromechanical ultrasonic transducer substrate 322, wherein the piezoelectric micromechanical ultrasonic transducer substrate 322 carries the piezoelectric micromechanical ultrasonic transducer array 320 and together constitutes a piezoelectric micromechanical ultrasonic transducer array structure, which is fixed to one side of the housing interior opposite to the reflector plate 220 via a non-elastic block 321.

[0044] In this embodiment, the piezoelectric micromechanical ultrasonic transducer array structure has multiple piezoelectric micromechanical ultrasonic transducer arrays 320, the elastic block array 221 is an array structure of a corresponding number, and similarly, the reflector array 220 is also an array structure of the same number, so that multi-axis acceleration sensing detection can be achieved; when the elastic block array 221 at any position is deformed, the distance between the piezoelectric micromechanical ultrasonic transducer array 320 at each position and the reflector array 220 at the corresponding position is only affected by the elastic deformation of the elastic block array 221, thus avoiding signal interference and crosstalk between arrays, and being able to more accurately judge the direction and magnitude of acceleration.

[0045] Figure 4 FIG. 1 is a schematic diagram of the structure of an acceleration sensor according to an embodiment of the present invention; Figure 4 As shown, the acceleration sensor comprises:

[0046] A housing 130; a reflector 230, fixed to one side of the housing interior via an elastic block 231; a piezoelectric micromechanical ultrasonic transducer 330, fixed to one side of the housing interior opposite to the reflector 230 via a non-elastic block 331; an application-specific integrated circuit (ASIC) 333, fixed to one side of the housing interior opposite to the reflector 230 and adjacent to the piezoelectric micromechanical ultrasonic transducer 330 via a non-elastic block 334.

[0047] In this embodiment, the dedicated integrated circuit 333 is also fixed inside the housing 130, and can achieve integration and integrity while realizing the acceleration sensing function; illustratively, the dedicated integrated circuit 333 can be a chip equipped with advanced signal processing algorithms, such as signal processing, time difference measurement and other algorithms, which can analyze and process the signals output by the piezoelectric micromechanical ultrasonic transducer.

[0048] Figure 5 FIG. 1 is a schematic diagram of an acceleration sensor according to an embodiment of the present invention applying acceleration in a first direction. Figure 5 As shown, when an acceleration in a first direction is applied, the distance between the reflection plate 200 and the piezoelectric micromechanical ultrasonic transducer 300 changes. At this time, the distance between the reflection plate 200 and the piezoelectric micromechanical ultrasonic transducer 300 is d1.

[0049] Figure 6 FIG. 1 is a schematic diagram of an acceleration sensor according to an embodiment of the present invention applying acceleration in a second direction. Figure 6 As shown, when the acceleration in the second direction is applied, the distance between the reflection plate 200 and the piezoelectric micromechanical ultrasonic transducer 300 changes. At this time, the distance between the reflection plate 200 and the piezoelectric micromechanical ultrasonic transducer 300 is d2.

[0050] It can be seen that when acceleration in different directions is applied, the distance between the reflector 200 and the piezoelectric micromechanical ultrasonic transducer 300 will change. By detecting the time when the piezoelectric micromechanical ultrasonic transducer 300 transmits and receives ultrasonic signals, the corresponding distance can be solved.

[0051] Figure 7 A high temperature stability acceleration detection method based on PMUT is provided in one embodiment of the present invention. Figure 7 As shown, the method includes:

[0052] The piezoelectric micromechanical ultrasonic transducer transmits a sound wave signal to the reflector;

[0053] The piezoelectric micromechanical ultrasonic transducer receives the echo signal reflected by the reflector;

[0054] The TOF time is calculated based on the time interval between the echo signal received by the piezoelectric micromechanical ultrasonic transducer and the peak value of the transmitted acoustic wave signal;

[0055] If the TOF time is inconsistent with the preset TOF time, acceleration is detected.

[0056] In the embodiment of the present invention, the piezoelectric micromechanical ultrasonic transducer is both a transmitting unit and a receiving unit. The sound wave excited by the piezoelectric micromechanical ultrasonic transducer contacts the reflector and then reflects back and is received by the piezoelectric micromechanical ultrasonic transducer. By calculating the time interval between the two signal peaks, the TOF time can be obtained. If the TOF time is inconsistent with the preset TOF time measured without external acceleration, it means that external acceleration has been suffered at this time. Of course, if the acceleration always exists, the TOF is a fixed value.

[0057] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "outside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 on the present invention.

[0058] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "rotation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A PMUT-based high temperature stability acceleration sensor, characterized in that: include: shell; A reflector is fixed to one side of the inner part of the shell through an elastic block; The piezoelectric micromechanical ultrasonic transducer is fixed on one side of the inner part of the housing directly facing the reflecting plate through a non-elastic block.

2. The PMUT-based high temperature stability acceleration sensor according to claim 1, characterized in that: The piezoelectric micromechanical ultrasonic transducer is a single or array structure.

3. The PMUT-based high temperature stability acceleration sensor according to claim 2, characterized in that: The elastic block is an array structure; the array structure of the elastic block corresponds to the array structure of the piezoelectric micromechanical ultrasonic transducer.

4. The PMUT-based high temperature stability acceleration sensor according to claim 1 or 3, characterized in that: The material of the elastic block includes polyurethane adhesive, silicone rubber adhesive or acrylic adhesive.

5. The PMUT-based high temperature stability acceleration sensor according to claim 3, characterized in that: The reflective plate is an array structure; the array structure of the reflective plate corresponds to the array structure of the elastic blocks.

6. The PMUT-based high temperature stability acceleration sensor according to claim 1, characterized in that: It also includes a dedicated integrated circuit, which is fixed on a side of the inner part of the housing opposite to the reflection plate and adjacent to the piezoelectric micromechanical ultrasonic transducer.

7. A high temperature stability acceleration detection method based on PMUT, characterized in that: The high temperature stability acceleration sensor based on PMUT as claimed in any one of claims 1 to 6 is applied, and the method comprises: The piezoelectric micromechanical ultrasonic transducer transmits a sound wave signal to the reflector; The piezoelectric micromechanical ultrasonic transducer receives the echo signal reflected by the reflector; The TOF time is calculated based on the time interval between the echo signal received by the piezoelectric micromechanical ultrasonic transducer and the peak value of the transmitted acoustic wave signal; If the TOF time is inconsistent with the preset TOF time, acceleration is detected.

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