Quartz tuning fork accelerometer with enhanced temperature environment adaptability

Abstract

The application provides a quartz vibrating beam accelerometer with enhanced temperature environment adaptability, wherein a TO package of a sensitive structure is not fixedly installed to an accelerometer shell in a conventional metal connection mode, but is fixed to an inner wall of the shell through a ring-shaped glue body, so that the influence of external environment temperature change can be reduced, and the temperature performance of the accelerometer is improved; a heat insulation baffle is installed between a circuit and a head of the sensitive structure, so that the temperature gradient between double beams of the sensitive structure caused by the start-up temperature rise of the circuit can be effectively reduced, and the start-up time of the accelerometer is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of MEMS inertial instruments or inertial devices, and relates to a quartz vibrating beam accelerometer with enhanced temperature environment adaptability, which has good temperature performance. BACKGROUND

[0002] The quartz vibrating beam accelerometer is based on the piezoelectric principle for resonant excitation and charge detection, has high detection sensitivity, excellent material mechanical and temperature characteristics, a simple structure and measurement and control circuit, good long-term stability, and the like, is one of important development directions of high-precision and small-size accelerometers, and has been widely applied in the fields of industry, aviation, aerospace, weapons, and the like at home and abroad. Foreign quartz vibrating beam accelerometers, such as EMCORE SDI500 and TAC-440 IMU combined accelerometers of the United States and Ixblue A5 series integrated vibrating beam accelerometers of France, have reached the level of navigation in precision, and the typical values of full-temperature bias and scale factor stability are better than 20 μg and 20 ppm, respectively. In China, the quartz vibrating beam accelerometer has also developed rapidly due to the accumulation of researches on quartz materials, micro-processing technology, and excitation circuits for many years, and the normal temperature performance of the accelerometer has approached the level of foreign countries, but the full-temperature characteristics, especially under different temperature environments or when the environmental temperature changes rapidly and randomly, still have a certain gap with foreign countries, and the typical values of full-temperature bias and scale factor stability are at the level of 100 μg and 100 ppm, respectively. At the same time, the sensitive structure of the quartz vibrating beam accelerometer generally adopts a double-beam differential design, and the heat generated in the starting process of the circuit often causes a temperature gradient between the double beams, resulting in a long output stabilization time, that is, a long starting time. Therefore, the temperature environment adaptability and starting time of the quartz vibrating beam accelerometer need to be improved.

[0003] In order to improve the temperature environment adaptability of the quartz vibrating beam accelerometer, the following problems need to be improved or solved:

[0004] (1) Weak temperature environment adaptability.

[0005] When the temperature of the working environment changes rapidly or irregularly, on the one hand, the total temperature change transmitted to the sensitive structure of the accelerometer is large, resulting in a large change in the frequency output of the resonant beam; on the other hand, the temperature gradient problem caused by the temperature change makes the differential effect of the double resonant beam worse, and the effect of the conventional gradient compensation algorithm is also worse, resulting in a significant decrease in the temperature performance of the accelerometer.

[0006] (2) Long starting time.

[0007] The general sensitive structure is packaged into a meter head through a metal shell, and is directly fixed on the metal shell of the accelerometer by laser welding. During the starting process of the accelerometer, the heat generated by the circuit changes the temperature of the double resonant beam through conduction, radiation and other ways. Due to the different spatial positions, the frequency change process of the double resonant beam is not consistent with the temperature change, so that the stable time of the frequency difference output, that is, the starting time, is often long, mostly in 50s-200s, which does not meet the application requirements in some fields. SUMMARY

[0008] The present application aims to at least solve one of the technical problems existing in the prior art or related art.

[0009] To this end, the present application provides a quartz vibrating beam accelerometer with enhanced temperature environment adaptability. The present application not only reduces the influence of rapid or irregular changes in the environmental temperature on the sensitive structure of the meter head, improves the temperature environment adaptability, and improves the temperature performance index of the accelerometer. At the same time, the influence of the circuit starting temperature rise on the sensitive structure of the meter head can also be reduced, and the starting time of the accelerometer can be shortened.

[0010] The technical solution of the present application is as follows:

[0011] The present application provides a quartz vibrating beam accelerometer with enhanced temperature environment adaptability, which comprises: an accelerometer internal component, a mounting flange, a meter sealing bottom plate and an accelerometer shell, the accelerometer internal component is arranged in the accelerometer shell, and comprises a sensitive structure, a stress isolation sheet, a meter head TO, a meter head TO cap, an annular glue body, a circuit TO, a heat insulation baffle and a rigid-flex PCB circuit board.

[0012] The sensitive structure is fixed in the inner cavity of the meter head TO through the stress isolation sheet, and after the inner cavity of the meter head TO is filled with nitrogen or argon, the meter head TO cap is used for laser seam welding to realize the airtight packaging of the sensitive structure in the meter head TO. The meter head TO is fixed on the inner wall of the accelerometer shell through a ring-shaped glue body around the outer diameter, the insulator pin array on the upper side of the meter head TO passes through the patterned via of the heat insulation baffle and is connected with the lower side circuit board of the rigid-flex PCB circuit board, realizing the electrical connection between the sensitive structure and the rigid-flex PCB circuit board. The heat insulation baffle is fixed on the accelerometer shell by adhesion, and is located between the rigid-flex PCB circuit board and the meter head TO. The upper side circuit board of the rigid-flex PCB circuit board is fixed on the circuit TO, and the insulator pin array on the circuit TO is used for the electrical connection between the accelerometer and the external application system.

[0013] The accelerometer whole watch cavity is extracted to a preset vacuum degree or filled with one atmosphere of argon, and then the whole watch sealing bottom plate is welded to the accelerometer shell to realize vacuum or air-tight packaging of the accelerometer whole watch.

[0014] Further, the watch head TO is fixed to the inner wall of the accelerometer shell through a ring-shaped glue body in the outer diameter, and the realization is achieved through the following way:

[0015] The sealed watch head TO is connected with the designed upper auxiliary positioning tool and is positioned through the blind hole on the watch head, the accelerometer shell is placed on the designed lower auxiliary positioning tool and can move up and down, front and back and left and right to realize the alignment with the watch head TO.

[0016] The watch head TO has a ring-shaped or special-shaped protrusion outside, which is used to form a slit with a set distance between the inner wall of the accelerometer shell, the glue liquid is poured in the slit, and the ring-shaped glue body is formed after drying and curing; after the glue body is cured, the upper auxiliary positioning tool and the lower auxiliary positioning tool are removed, and the watch head TO is positioned and fixed to the accelerometer shell.

[0017] Further, the set distance is 50um-500um.

[0018] Further, the circuit TO is fixed to the accelerometer shell through a laser welding ring.

[0019] Further, the whole watch sealing bottom plate is welded to the accelerometer shell through a laser welding ring.

[0020] Further, the sensitive structure is a split type or an integral type structure, and the sensitive structure can be a single beam or a double beam, or a metal pendulum or a quartz pendulum.

[0021] Compared with the prior art, the present application has at least the following beneficial effects:

[0022] (1) Improve the temperature environment adaptability of the accelerometer and improve the full-temperature performance:

[0023] The present application fixes the watch head by using the heat-insulating glue body, increases the stress isolation sheet, realizes two-stage heat insulation of the whole watch and the watch head TO, and optimizes the heat treatment of the inner wall of the shell and the watch head TO, which on the one hand reduces the total heat of the environmental temperature change conducted and radiated to the sensitive structure, and reduces the frequency change of the single beam; on the other hand, reduces the temperature gradient and gradient change rate between the double resonant beams, and improves the differential and temperature compensation effect. Finally, the temperature environment adaptability is improved, and the full-temperature performance of the accelerometer is improved.

[0024] (2) Reduce the start-up time of the accelerometer:

[0025] The application can reduce the influence of the start-up temperature rise on the sensitive structure inside the table head TO, shorten the stable process of the double-beam frequency difference output, and reduce the start-up time of the accelerometer by arranging the table head TO and the circuit TO on both sides of the mounting flange, maximizing the distance between the table head and the circuit, increasing the heat insulation baffle, and other methods. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is readily apparent to one skilled in the art that the following description in the drawings is merely illustrative of some embodiments of the application and that numerous other embodiments can be derived from these drawings without departing from the spirit of the application.

[0027] Figure 1 It is a quartz vibrating beam accelerometer scheme with enhanced temperature environment adaptability.

[0028] Figure 2 It is an implementation mode in which the table head TO is fixedly mounted to the shell through the annular glue. DETAILED DESCRIPTION

[0029] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0030] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or their combinations.

[0031] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not intended to limit the scope of the application unless specifically stated otherwise. It is to be understood that the various parts shown in the drawings are not necessarily drawn to scale and that, for the purposes of convenience and clarity, not all of the routine features of the technologies, methods and devices are shown or described in detail. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail but are intended to be a part of the scope of the present application. In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation on the scope of the exemplary embodiments. Thus, other examples of the exemplary embodiments can have different values. It is noted that like numbers and letters on the figures identify like parts throughout the several views, and that, where possible, like reference numerals are used throughout the several figures, and that, where first reference numerals can have been used, subsequent reference numerals can not have been discussed further, but are intended to be a part of the scope of the present application.

[0032] As shown in Figure 1 , the embodiment provides a temperature environment adaptability enhanced quartz vibrating beam accelerometer. First, the sensitive structure 7 is fixed in the table head TO 6 by the stress isolation sheet 5, and then after the links such as baking and degassing, the table head TO 6 is filled with nitrogen or argon, and then the laser seam welding is performed by using the table head TO cap 8 to realize the airtight packaging of the sensitive structure 7 in the table head TO 6. Then, the table head TO 6 is fixed on the accelerometer shell 12 through a ring of glue 13. The insulator pin array 3 on the upper side of the table head TO 6 passes through the patterned via of the heat insulation baffle 11 and is connected with the rigid-flex PCB circuit 9 to realize the electrical connection of the sensitive structure 7 and the circuit 9. The heat insulation baffle 11 is fixed on the accelerometer shell 12 by glue. The upper circuit board of the rigid-flex PCB circuit 9 is fixed on the circuit TO 2, and the lower circuit board is connected with the insulator pin array 3 on the upper side of the table head TO 6. The circuit TO 2 is fixed on the accelerometer shell 12 by the laser welding ring 10. Finally, after the whole watch cavity of the accelerometer is pumped to a preset vacuum degree or filled with argon and other low thermal conductivity gases, the whole watch sealing bottom plate 15 is welded to the accelerometer shell 12 by the laser welding ring 14 to realize the vacuum or airtight packaging of the whole watch of the accelerometer. The insulator pin array 1 on the circuit TO 2 is used for the electrical connection of the accelerometer and the external application system, and the mounting flange 4 is used for the fixed installation of the accelerometer.

[0033] That is, after the sensitive structure 7 is installed on the table head TO 6, it is not directly installed and fixed to the metal shell 12 of the accelerometer, but is fixed to the inner wall of the shell through the ring-shaped glue 13 to reduce the influence of the external environment temperature change and improve the temperature environment adaptability of the accelerometer. The heat insulation baffle 11 is installed between the circuit 9 and the table head TO 6 to reduce the temperature gradient between the double beams of the sensitive structure caused by the start-up temperature rise of the circuit and shorten the start-up time of the accelerometer.

[0034] It can be seen that the sensitive structure 7 is mounted on the meter head TO 6 through the stress isolation sheet 5, and is fixed to the metal shell 12 through the heat insulation glue 13 after airtight packaging. The meter head TO 6 and the circuit TO 2 are located on both sides of the accelerometer mounting flange, and the heat insulation baffle 11 is arranged between the meter head TO 6 and the circuit TO 2 to block the heat radiation and natural convection of the circuit 9 to the meter head TO 6. The accelerometer whole meter is packaged by argon airtight or low vacuum, and the principle is similar to that of a thermos, so that the influence of the external temperature environment on the internal meter head is reduced. The surface of the outer wall of the meter head TO 6 is mirror-finished, and the inside of the shell is blackened and sandblasted, so that the heat radiation isolation effect is further enhanced.

[0035] Figure 2 An implementation mode that the meter head TO 6 is accurately positioned and fixed to the shell 12 through the annular glue 13 is given. The sealed meter head TO 6 is connected with the upper auxiliary positioning tool 17 and is accurately positioned through the blind hole 18, the accelerometer shell 12 is placed on the lower auxiliary positioning tool 19, and can be finely moved up and down, forward and backward and left and right to realize accurate alignment with the meter head TO 6. The annular protrusion 16 outside the meter head TO 6 is used to form a 50um-500um gap between the inner wall of the accelerometer shell 12. The glue liquid is poured in the gap, and the annular glue 13 is formed after drying and curing. After the glue 13 is cured, the upper auxiliary positioning tool 17 and the lower auxiliary positioning tool 19 are removed, and the meter head TO 6 can be accurately positioned and fixed to the accelerometer shell 12.

[0036] Optionally, the sensitive structure of the quartz vibrating beam accelerometer can be a split structure or an integrated structure, can be a single beam or a double beam, or can be a metal pendulum or a quartz pendulum.

[0037] It can be seen that, by using the heat insulation glue to fix the meter head, adding the stress isolation sheet, implementing two-stage heat insulation of the whole meter and the meter head TO, and optimizing the heat treatment of the inner wall of the shell, the embodiment of the application reduces the total heat quantity of the environmental temperature change conducted and radiated to the sensitive structure, reduces the frequency change quantity of the single beam, reduces the temperature gradient and gradient change rate between the double resonant beams, improves the differential and temperature compensation effect, finally improves the temperature environment adaptability of the accelerometer and improves the whole temperature performance. In addition, by arranging the meter head TO and the circuit TO on both sides of the mounting flange, increasing the distance between the meter head and the circuit as much as possible, and adding the heat insulation baffle, the embodiment of the application conducts the start-up temperature rise of the circuit to the mounting carrier through the mounting flange as much as possible, reduces the heat quantity radiated and naturally flowed to the meter head TO, thereby suppressing the influence of the start-up temperature rise on the internal sensitive structure of the meter head TO as much as possible, shortening the stable process of the frequency difference output of the double beams, and reducing the start-up time of the accelerometer.

[0038] Features as described and / or illustrated above in relation to one embodiment can be used in the same or similar way in one or more other embodiments and / or combined with or substituted for features in other embodiments.

[0039] It is to be emphasized that the terms "comprises / comprising" when used in this specification are taken to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0040] Many features and advantages of the embodiments are apparent from the detailed description, thus, the appended claims are intended to cover all such features and advantages of the embodiments within their true spirit and scope. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the embodiments of the present application to the exact construction and operation described and illustrated, and accordingly, all suitable modifications and equivalents can be resorted to, falling within the scope of the present application.

[0041] Portions of the present application that are of reasonable expectation for one of ordinary skill in the art are not described in detail.

Claims

1. A temperature environment-adapted enhanced quartz tuning fork accelerometer, characterized by, The accelerometer comprises an accelerometer internal component, a mounting flange, a whole watch sealing bottom plate and an accelerometer shell, the accelerometer internal component is arranged in the accelerometer shell and comprises a sensitive structure, a stress isolation sheet, a watch head TO, a watch head TO cap, an annular glue body, a circuit TO, a heat insulation baffle and a rigid-flex PCB circuit board; The sensitive structure is fixed in the inner cavity of the watch head TO through the stress isolation sheet, and after the inner part of the watch head TO is filled with nitrogen or argon, laser seam welding is performed using the watch head TO cap to realize the airtight packaging of the sensitive structure in the watch head TO; the watch head TO is fixed on the inner wall of the accelerometer shell through a ring of annular glue bodies in the outer diameter, the insulator pin array on the upper side of the watch head TO passes through the patterned via of the heat insulation baffle and is connected with the lower side circuit board of the rigid-flex PCB circuit board, thereby realizing the electrical connection of the sensitive structure and the rigid-flex PCB circuit board; the heat insulation baffle is fixed on the accelerometer shell through an adhesive method and is located between the rigid-flex PCB circuit board and the watch head TO; the upper side circuit board of the rigid-flex PCB circuit board is fixed to the circuit TO, and the insulator pin array on the circuit TO is used for the electrical connection between the accelerometer and the outside; Wherein, after the whole watch cavity of the accelerometer is extracted to a preset vacuum degree or filled with argon, the whole watch sealing bottom plate is welded to the accelerometer shell to realize the vacuum or airtight packaging of the whole watch of the accelerometer, the mounting flange is arranged on the accelerometer shell and is used for the fixed installation of the accelerometer, and the watch head TO and the circuit TO are distributed on the two sides of the mounting flange; The watch head TO is fixed on the inner wall of the accelerometer shell through a ring of annular glue bodies in the outer diameter, and the following methods are used to realize the fixing: The sealed watch head TO is connected with the designed upper auxiliary positioning tooling and is positioned through the blind hole on the watch head, the accelerometer shell is placed on the designed lower auxiliary positioning tooling and can move up and down, forward and backward and left and right, which is used for realizing the alignment with the watch head TO; The watch head TO has a ring-shaped or special-shaped protrusion outside, which is used for forming a slit with a set distance between the inner wall of the accelerometer shell, pouring glue liquid in the slit, and forming an annular glue body after drying and curing; after the glue body is cured, the upper auxiliary positioning tooling and the lower auxiliary positioning tooling are removed, and the watch head TO is positioned and fixed to the accelerometer shell.

2. A temperature environment-adapted enhanced quartz tuning fork accelerometer according to claim 1, characterized in that The set distance is 50um-500um.

3. A temperature environmentally enhanced quartz tuning fork accelerometer according to claim 1, wherein, The circuit TO is fixed on the accelerometer shell through laser welding.

4. A temperature environment-adapted enhanced quartz tuning fork accelerometer according to claim 1 or 3, characterized in that, The sealing bottom plate is welded to the accelerometer shell through a laser welding ring.

5. A temperature environmentally enhanced quartz tuning fork accelerometer according to claim 1, wherein, The sensitive structure is a split type or an integral type structure, and the sensitive structure can be a single beam or a double beam, or a metal pendulum or a quartz pendulum.

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