Surface acoustic wave acceleration sensor with temperature compensation

Abstract

The invention discloses a temperature-compensated surface acoustic wave acceleration sensor, which comprises a circular membrane support structure, a mass block, a signal adapter plate, a metal lead, a surface acoustic wave temperature resonator, two surface acoustic wave acceleration resonators and two signal transmission lines, and is characterized in that the circular membrane support structure comprises a base, a central support column and a circular membrane; the mass block is fixed with the side wall of the round film; the signal adapter plate and the two surface acoustic wave acceleration resonators are positioned on the inner surface of the circular film; electrode signal ends and ground ends of the first surface acoustic wave acceleration resonator, the second surface acoustic wave acceleration resonator and the surface acoustic wave temperature resonator are respectively connected in parallel through two signal transmission lines; and the common signal ends and the ground ends of the electrodes of the first surface acoustic wave acceleration resonator, the second surface acoustic wave acceleration resonator and the surface acoustic wave temperature resonator are respectively connected to the signal end and the ground end of the signal adapter plate through metal leads. The sensor is good in integration level, high in acceleration sensitivity and capable of achieving in-situ temperature compensation.

Description

Technical Field

[0001] The invention relates to a temperature-compensated surface acoustic wave acceleration sensor, belonging to the field of sensors. Background Art

[0002] As a new type of measurement method, surface acoustic wave acceleration sensor has attracted wide attention due to its small size, high sensitivity, easy integration, easy signal acquisition and processing, etc. In particular, the surface acoustic wave sensor itself has a unique wireless passive detection method, avoiding the influence of cables and power supply, and showing great application prospects in the measurement of complex and harsh environments such as high temperature, strong radiation, confinement and rotation.

[0003] In order to ensure the measurement accuracy of the surface acoustic wave accelerometer, its temperature error needs to be compensated. Traditional methods of reducing and compensating temperature errors include: (1) using surface acoustic wave devices that are insensitive to temperature; (2) making the accelerometer work in a constant temperature environment; (3) adding materials or components to the structure that offset temperature changes; (4) systematically obtaining the temperature characteristics of the accelerometer and correcting them.

[0004] The shortcomings of traditional methods are: lack of effective in-situ temperature compensation, or complex temperature compensation structure and difficult process implementation. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a temperature-compensated surface acoustic wave acceleration sensor, which has the characteristics of good integration, high acceleration sensitivity and in-situ temperature compensation.

[0006] The technical solution of the present invention is: a temperature-compensated surface acoustic wave acceleration sensor, comprising: a circular membrane support structure, a mass block, a signal adapter plate, a metal lead, a first surface acoustic wave acceleration resonator, a second surface acoustic wave acceleration resonator, a surface acoustic wave temperature resonator, a first signal transmission line and a second signal transmission line, wherein:

[0007] The circular membrane support structure includes a base, a central pillar and a circular membrane, wherein the central pillar is located on the base and the circular membrane is located on the central pillar;

[0008] The mass block is fixed to the side wall of the circular membrane;

[0009] The signal transfer board, the first surface acoustic wave acceleration resonator, the second surface acoustic wave acceleration resonator, and the surface acoustic wave temperature resonator are located on the inner surface of the circular membrane, wherein:

[0010] The electrode signal terminals and ground terminals of the first surface acoustic wave acceleration resonator, the second surface acoustic wave acceleration resonator, and the surface acoustic wave temperature resonator are connected in parallel through the first signal transmission line and the second signal transmission line respectively;

[0011] The common signal end and ground end of the electrodes of the first SAW acceleration resonator, the second SAW acceleration resonator and the SAW temperature resonator are respectively connected to the signal end and ground end of the signal adapter board through metal leads.

[0012] Preferably, the circular membrane support structure and the mass block are both made of metal materials;

[0013] The mass block is fixed to the side wall of the circular membrane by bonding or welding, and a hole is arranged on the mass block.

[0014] Preferably, the signal adapter plate is located in the circular membrane area above the central pillar: when the sensor is subjected to acceleration, the area does not deform, and the signal adapter plate is not affected by stress and strain.

[0015] Preferably, the first surface acoustic wave acceleration resonator, the second surface acoustic wave acceleration resonator, and the surface acoustic wave temperature resonator are composed of a piezoelectric substrate and a metal electrode arranged on the surface of the substrate; the piezoelectric substrate is made of piezoelectric quartz, piezoelectric lithium niobate or piezoelectric lithium tantalate, and the surface electrode material is made of aluminum, gold or platinum.

[0016] Preferably, the first surface acoustic wave acceleration resonator and the second surface acoustic wave acceleration resonator are away from the central support and are placed in a region on the circular membrane where stress and strain are greater.

[0017] Preferably, the distances between the circular membrane positions of the first surface acoustic wave acceleration resonator and the second surface acoustic wave acceleration resonator and the central pillar are not equal, and the corresponding stress and strain polarities are opposite.

[0018] Preferably, the first surface acoustic wave acceleration resonator and the second surface acoustic wave acceleration resonator use the same piezoelectric substrate cut type, the same metal electrode thickness, and similar electrical period size to obtain the same temperature characteristics, and only the resonance frequency is different;

[0019] Among them, the electrical cycle size difference range is ≤4%.

[0020] Preferably, the surface acoustic wave temperature resonator is located around the signal adapter plate and close to the center of the circular membrane.

[0021] Preferably, the surface acoustic wave temperature resonator uses a piezoelectric substrate cut type different from that of the first surface acoustic wave acceleration resonator and the second surface acoustic wave acceleration resonator, and the cut type is insensitive to stress and strain.

[0022] Preferably, the signal adapter board can be equipped with an external radio frequency cable and antenna to achieve wireless passive measurement.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention effectively improves the sensitivity of the acceleration sensor and reduces the influence of temperature and other common-mode interference through the differential design of two acceleration resonators;

[0025] (2) The present invention realizes in-situ temperature measurement by arranging a temperature sensor that is insensitive to acceleration on the inner surface of the circular membrane, and systematically obtains the temperature characteristics of the acceleration sensor, which can be further used for temperature compensation, and the process is not complicated;

[0026] (3) The present invention can fully utilize the surface space of the circular membrane and has a high integration level. Subsequently, the wireless passive measurement of acceleration and temperature parameters can be realized through an external antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The structure diagram of the temperature-compensated surface acoustic wave acceleration sensor of the present invention;

[0028] Figure 2 It is the frequency-acceleration characteristic experimental curve of the acceleration resonator 1 in the temperature-compensated surface acoustic wave acceleration sensor of the present invention;

[0029] Figure 3 It is the frequency-acceleration characteristic experimental curve of the acceleration resonator 2 in the temperature-compensated surface acoustic wave acceleration sensor of the present invention;

[0030] Figure 4 The frequency-acceleration characteristic experimental curve of the temperature resonator in the temperature-compensated surface acoustic wave acceleration sensor of the present invention;

[0031] Figure 5 The frequency-temperature characteristic experimental curve of the temperature resonator in the temperature-compensated surface acoustic wave acceleration sensor of the present invention;

[0032] Figure 6 This is an experimental curve of the frequency-acceleration characteristic after the differential output of the acceleration resonator 2 and the acceleration resonator 1 in the temperature-compensated surface acoustic wave acceleration sensor of the present invention. DETAILED DESCRIPTION

[0033] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a temperature-compensated surface acoustic wave acceleration sensor, to adopt a circular membrane-mass block structure as an acceleration transmission device, and to arrange three resonators, namely, a surface acoustic wave temperature resonator, a first surface acoustic wave acceleration resonator and a second surface acoustic wave acceleration resonator, on the inner surface of the circular membrane. The first surface acoustic wave acceleration resonator and the second surface acoustic wave acceleration resonator work differentially to improve the acceleration sensitivity, reduce the temperature influence, and realize the acceleration sensing function; the temperature sensing function is realized by the temperature resonator, and temperature compensation can be further performed to improve the accuracy of the acceleration sensor. The signal is transmitted through the antenna, and the wireless passive measurement of the surface acoustic wave acceleration and temperature sensor can be realized, which has the characteristics of good integration, high acceleration sensitivity, and in-situ temperature compensation.

[0034] A temperature compensated surface acoustic wave accelerometer, such as Figure 1 As shown, it includes a circular membrane support structure 1, a mass block 2, a signal adapter board 3, a metal lead 4, a first surface acoustic wave acceleration resonator 5, a second surface acoustic wave acceleration resonator 6, a surface acoustic wave temperature resonator 7, a first signal transmission line 8 and a second signal transmission line 9.

[0035] The circular membrane support structure 1 is composed of a base, a central support, a circular membrane and its side walls, and is made of metal material.

[0036] The mass block 2 is made of metal material and fixed to the side wall of the circular membrane by bonding or welding. A small hole is arranged on the mass block 2.

[0037] The inner surface of the circular membrane of the circular membrane support structure 1 is provided with a signal adapter board 3, a metal lead 4, a surface acoustic wave acceleration resonator 15, a second surface acoustic wave acceleration resonator 6, a surface acoustic wave temperature resonator 7, a first signal transmission line 8, and a second signal transmission line 9.

[0038] The signal transfer board 3 is located in the circular membrane area above the central pillar. When the sensor is subjected to acceleration, this area does not deform, and the signal transfer board is not affected by stress and strain.

[0039] The first surface acoustic wave acceleration resonator 5, the second surface acoustic wave acceleration resonator 6, and the surface acoustic wave temperature resonator 7 are composed of a piezoelectric substrate and a metal electrode arranged on the surface of the substrate. The piezoelectric substrate is made of piezoelectric quartz, piezoelectric lithium niobate or piezoelectric lithium tantalate, and the surface electrode is made of metal materials such as aluminum, gold or platinum.

[0040] The electrode signal terminals and ground terminals of the first SAW acceleration resonator 5, the second SAW acceleration resonator 6 and the SAW temperature resonator 7 are connected in parallel through the first signal transmission line 8 and the second signal transmission line 9 respectively. The signal transmission lines can be electrical conductors such as planar electrode leads and metal leads.

[0041] The common signal terminal and ground terminal of the electrodes of the first SAW acceleration resonator 5 , the second SAW acceleration resonator 6 , and the SAW temperature resonator 7 are connected to the signal terminal and ground terminal of the signal adapter board 3 through metal leads 4 , respectively.

[0042] The first SAW acceleration resonator 5 and the second SAW acceleration resonator 6 are placed away from the center and are located in a region with large stress and strain. The first SAW acceleration resonator 5 and the second SAW acceleration resonator 6 have opposite stress and strain polarities at the circular membrane locations.

[0043] The first SAW acceleration resonator 5 and the second SAW acceleration resonator 6 use the same piezoelectric substrate cut, the same metal electrode thickness, and similar electrical period sizes, with the electrical period size difference range of ≤4% to obtain the same temperature characteristics, with only a difference in resonant frequency.

[0044] The surface acoustic wave temperature resonator 7 is located around the signal adapter plate 3, close to the center of the circular membrane, and there is no obvious stress-strain effect in this area.

[0045] The surface acoustic wave temperature resonator 7 uses a piezoelectric substrate cut type different from that of the first surface acoustic wave acceleration resonator 5 and the second surface acoustic wave acceleration resonator 6, and the cut type is insensitive to stress and strain.

[0046] One end of the metal lead 4 is connected to the signal adapter board 3, and the other end is connected to the signal transmission line to realize the electrical connection between the resonator and the signal adapter board. Wireless passive measurement can be realized by externally placing a radio frequency cable and an antenna on the signal adapter board 3.

[0047] Example:

[0048] A temperature compensated surface acoustic wave accelerometer, such as Figure 1 As shown, it includes a circular membrane support structure 1, a mass block 2, a signal adapter board 3, a metal lead 4, a first surface acoustic wave acceleration resonator 5, a second surface acoustic wave acceleration resonator 6, a surface acoustic wave temperature resonator 7, a first signal transmission line 8 and a second signal transmission line 9.

[0049] The circular membrane support structure 1 is composed of a base, a central pillar, a circular membrane and its side walls, and is made of stainless steel. The radius of the circular membrane is 12mm, and the diameter of the central pillar is also 4mm. Therefore, the 4mm diameter plane area at the center of the circular membrane is fixed, and the area outside this area is a movable deformation area.

[0050] The mass block 2 is made of a high specific gravity alloy material and is fixed to the side wall of the circular membrane by welding. A small hole is provided on the mass block 2.

[0051] The inner surface of the circular membrane of the circular membrane support structure 1 is provided with a signal adapter board 3, a metal lead 4, a first surface acoustic wave acceleration resonator 5, a second surface acoustic wave acceleration resonator 6, a surface acoustic wave temperature resonator 7, a first signal transmission line 8, and a second signal transmission line 9.

[0052] The signal transfer board 3 is located in the circular membrane area above the central pillar, with a diameter of 4 mm. When the sensor is subjected to acceleration, the signal transfer board is not affected by stress and strain.

[0053] The first SAW acceleration resonator 5, the second SAW acceleration resonator 6 and the SAW temperature resonator 7 are composed of a piezoelectric substrate and metal electrodes arranged on the surface of the substrate. The piezoelectric substrate is made of piezoelectric quartz material, the surface electrode is made of aluminum material, and the resonator size is 3mm×2mm.

[0054] The first SAW acceleration resonator 5, the second SAW acceleration resonator 6 and the SAW temperature resonator 7 are located on the inner surface of the circular membrane. When the sensor is subjected to acceleration, the stress and strain changes of the circular membrane will be transmitted to the SAW acceleration resonator thereon.

[0055] The center position of the first SAW acceleration resonator 5 is 9 mm outside the center of the circular membrane, and the center position of the second SAW acceleration resonator 6 is 7 mm outside the center of the circular membrane. Both the first SAW acceleration resonator 5 and the second SAW acceleration resonator 6 obtain large stress and strain, but the stress and strain polarities are opposite.

[0056] The first surface acoustic wave acceleration resonator 5 and the second surface acoustic wave acceleration resonator 6 use the same quartz piezoelectric substrate cut, the same metal aluminum electrode thickness, and similar electrical period size to obtain theoretically the same temperature characteristics. The center frequency of the first surface acoustic wave acceleration resonator 5 is 437.430MHz, and the center frequency of the second surface acoustic wave acceleration resonator 6 is 435.400MHz.

[0057] The surface acoustic wave temperature resonator 7 is placed adjacent to the signal adapter board 3, and its center is located 3.5 mm outside the center of the circular membrane.

[0058] The center frequency of the surface acoustic wave temperature resonator 7 is 438.570 MHz.

[0059] The first signal transmission line 8 interconnects one end of the interdigital transducers of the first surface acoustic wave acceleration resonator 5, the second surface acoustic wave acceleration resonator 6, and the surface acoustic wave temperature resonator 7 for electrical signals, and the second signal transmission line 9 interconnects the other end of the interdigital transducers of the first surface acoustic wave acceleration resonator 5, the second surface acoustic wave acceleration resonator 6, and the surface acoustic wave temperature resonator 7 for electrical signals, thereby realizing parallel operation of the surface acoustic wave resonators.

[0060] One end of the metal lead 4 is connected to the signal adapter board 3 , and the other end is connected to the signal transmission line, so as to realize the electrical connection between the resonator and the signal adapter board.

[0061] The sensor is tested for acceleration performance, with an acceleration test range of -15g to +15g, g = 9.8m / s 2 , the results are as follows:

[0062] Figure 2 : is the frequency-acceleration characteristic experimental curve of the first acceleration resonator 1 in the surface acoustic wave acceleration sensor. The frequency of the first acceleration resonator 1 shows a monotonically decreasing trend as the acceleration increases, and the full-scale output is -254kHz.

[0063] Figure 3 : is the frequency-acceleration characteristic experimental curve of the acceleration resonator 2 in the surface acoustic wave acceleration sensor. The frequency of the acceleration resonator 2 increases monotonically with the increase of acceleration, and the full-scale output is +174kHz.

[0064] Figure 4 The frequency-acceleration characteristic experimental curve of the temperature resonator in the surface acoustic wave acceleration sensor. The frequency of the temperature resonator remains basically unchanged as the acceleration changes, and the full-scale jitter is ±3kHz, which is within the reading error range.

[0065] Figure 5 This is the frequency-temperature characteristic experimental curve of the temperature resonator in the surface acoustic wave acceleration sensor. The frequency of the temperature resonator shows a monotonically decreasing trend as the temperature rises, and the full-scale output is -430kHz. Through this temperature characteristic curve, temperature compensation can be performed on the acceleration test of the sensor at different temperatures.

[0066] Figure 6 This is the frequency-acceleration characteristic experimental curve after the differential output of acceleration resonator 2 and acceleration resonator 1 in the surface acoustic wave acceleration sensor, and the output result is the test data of three forward and reverse strokes. The test results show that the sensitivity of the differential acceleration sensor is 14.3kHz / g and the accuracy is 1.97%FS.

[0067] The present invention adopts an acceleration transmission device of a circular membrane-mass block structure, using a circular membrane as a deformation structure, a mass block is arranged on top of it, and three surface acoustic wave resonators are arranged on the inner surface of the circular membrane, namely, a temperature resonator, an acceleration resonator 1 and an acceleration resonator 2. When the sensor is driven by acceleration, the mass block drives the circular membrane to produce deformation, which is transmitted to the surface acoustic wave resonator thereon, thereby causing the change of the acoustic wave characteristics of the resonator, resulting in the change of the output frequency of the resonator.

[0068] Among them, acceleration resonator 1 and acceleration resonator 2 use the same piezoelectric substrate cut and metal electrode structure, have the same sound wave-temperature sensitivity characteristics, and perform differential processing on the outputs of acceleration resonator 1 and acceleration resonator 2 to eliminate the influence of temperature on the sound wave and achieve temperature compensation effect.

[0069] Secondly, the acceleration resonator 1 and the acceleration resonator 2 are placed in different areas on the circular membrane. According to the stress and strain distribution characteristics of the circular membrane surface when the sensor is working, the acceleration resonator 1 and the acceleration resonator 2 are respectively placed in the areas of the circular membrane with opposite stress and strain polarities. The differential operation of the output of the acceleration resonator 1 and the output of the acceleration resonator 2 can further offset the temperature effect and improve the acceleration sensitivity.

[0070] In addition, the temperature resonator selects a different cut type from the acceleration resonator, and the temperature resonator is set in an area insensitive to stress and strain. The above-mentioned method 4 for compensating temperature errors is used to systematically obtain the ambient temperature of the entire sensor. Through software fitting, the temperature influence of the acceleration sensor can be further reduced and the sensor accuracy can be improved.

[0071] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A temperature-compensated surface acoustic wave acceleration sensor, characterized in that include: A circular membrane support structure (1), a mass block (2), a signal adapter plate (3), a metal lead (4), a first surface acoustic wave acceleration resonator (5), a second surface acoustic wave acceleration resonator (6), a surface acoustic wave temperature resonator (7), a first signal transmission line (8) and a second signal transmission line (9), wherein: The circular membrane support structure (1) comprises a base, a central pillar and a circular membrane, wherein the central pillar is located on the base and the circular membrane is located on the central pillar; The mass block (2) is fixed to the side wall of the circular membrane; The signal transfer board (3), the first surface acoustic wave acceleration resonator (5), the second surface acoustic wave acceleration resonator (6), and the surface acoustic wave temperature resonator (7) are located on the inner surface of the circular membrane, wherein: The electrode signal ends and ground ends of the first surface acoustic wave acceleration resonator (5), the second surface acoustic wave acceleration resonator (6), and the surface acoustic wave temperature resonator (7) are connected in parallel via a first signal transmission line (8) and a second signal transmission line (9), respectively; The common signal end and ground end of the electrodes of the first surface acoustic wave acceleration resonator (5), the second surface acoustic wave acceleration resonator (6) and the surface acoustic wave temperature resonator (7) are respectively connected to the signal end and ground end of the signal adapter board (3) through metal leads (4).

2. A temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The circular membrane support structure (1) and the mass block (2) are both made of metal materials; The mass block (2) is fixed to the side wall of the circular membrane by bonding or welding, and a hole is provided on the mass block (2).

3. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The signal transfer plate (3) is located in the circular membrane area above the central pillar: when the sensor is subjected to acceleration, this area does not deform, and the signal transfer plate is not affected by stress and strain.

4. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The first surface acoustic wave acceleration resonator (5), the second surface acoustic wave acceleration resonator (6), and the surface acoustic wave temperature resonator (7) are composed of a piezoelectric substrate and a metal electrode arranged on the surface of the substrate; the piezoelectric substrate is made of piezoelectric quartz, piezoelectric lithium niobate or piezoelectric lithium tantalate, and the surface electrode material is made of aluminum, gold or platinum.

5. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The first surface acoustic wave acceleration resonator (5) and the second surface acoustic wave acceleration resonator (6) are located away from the central support and are placed in an area on the circular membrane where stress and strain are relatively large.

6. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The distances between the circular membrane positions of the first surface acoustic wave acceleration resonator (5) and the second surface acoustic wave acceleration resonator (6) and the central pillar are unequal, and the corresponding stress and strain polarities are opposite.

7. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The first surface acoustic wave acceleration resonator (5) and the second surface acoustic wave acceleration resonator (6) use the same piezoelectric substrate cut type, the same metal electrode thickness, and similar electrical period size to obtain the same temperature characteristics, with only a difference in resonance frequency; Among them, the electrical cycle size difference range is ≤4%.

8. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The surface acoustic wave temperature resonator (7) is located around the signal adapter plate (3) and close to the center of the circular membrane.

9. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The surface acoustic wave temperature resonator (7) uses a piezoelectric substrate cut type different from that of the first surface acoustic wave acceleration resonator (5) and the second surface acoustic wave acceleration resonator (6), and the cut type is insensitive to stress and strain.

10. The temperature-compensated surface acoustic wave acceleration sensor according to claim 1, characterized in that: The signal adapter board (3) can be externally connected with a radio frequency cable and an antenna to achieve wireless passive measurement.

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