Sensor, sensor circuit board of z-axis sensitive direction and its calibration installation method

Abstract

This application discloses a sensor, a sensor circuit board with a Z-axis sensitive direction, and its calibration and installation method, applied in the field of detection technology. It includes: an accelerometer for detecting vibration and / or impact of a device under test, with the sensitive direction being the Z-axis; a base plate for supporting the accelerometer; a first flexible circuit board connected to the base plate; and a mounting plate with a conditioning circuit, having N layers, of which M is a flexible layer, with each flexible layer corresponding to a layer of the first flexible circuit board. The mounting plate receives sampling signals from the accelerometer through the base plate and the first flexible circuit board, processes the sampling signals through the conditioning circuit, and outputs the processed detection signal. The base plate has grooves to secure the mounting plate to the base plate during installation. Applying this solution supports installation in the Z-axis sensitive direction, effectively achieving sensor operating point calibration and sensitivity calibration, while ensuring the sensor's small size.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to a sensor, a sensor circuit board for the Z-axis sensitive direction, and its calibration and installation method. Background Technology

[0002] Accelerometers are vibration and shock sensitive devices during fault diagnosis. Currently, MEMS (Micro Electromechanical System) accelerometers are widely used due to their small size, high detection accuracy, shock resistance, and ease of mass production. Based on the sensing axis, accelerometers can be divided into in-plane and out-of-plane sensing directions; see reference [link to relevant documentation]. Figure 1 This is a schematic diagram of different sensitive directions of the accelerometer, where... Figure 1 The left side represents the in-plane sensing direction, and the right side represents the out-of-plane sensing direction. Currently, many high-performance MEMS accelerometers use the Z-axis sensing direction, which is the out-of-plane sensing direction. Such MEMS accelerometers usually need to be installed perpendicular to the vibration and shock direction (unlike in-plane sensitive MEMS installation).

[0003] Currently, MEMS accelerometers and peripheral circuits are typically soldered onto a single PCB (Printed Circuit Board) and then horizontally mounted inside the sensor housing. However, this type of PCB has a large area, resulting in a large overall sensor size, which cannot meet the requirements for small sensor size.

[0004] In summary, how to ensure the sensor's small size while allowing it to be installed in the Z-axis sensitive direction is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a sensor, a sensor circuit board in the Z-axis sensitive direction, and a calibration and installation method thereof, so as to ensure the small size of the sensor while satisfying the installation requirements in the Z-axis sensitive direction.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a sensor circuit board for the Z-axis sensing direction, comprising:

[0008] An accelerometer used to detect vibration and / or shock of the equipment under test, with the sensitive direction being the Z-axis;

[0009] The base plate used to support the accelerometer;

[0010] A first flexible circuit board connected to the base plate;

[0011] A mounting plate equipped with a conditioning circuit has N layers, of which M layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the first flexible circuit board. The mounting plate is used to receive the sampling signal of the accelerometer through the base plate and the first flexible circuit board, process the sampling signal through the conditioning circuit, and output the processed detection signal. Here, M and N are both positive integers, representing the number of layers of the first flexible circuit board and the mounting plate, respectively, and M≤N.

[0012] The base plate is provided with a groove so that the mounting plate is fixed to the base plate through the groove when the installation is completed.

[0013] In one embodiment, it further includes: a calibration circuit connected to the accelerometer for calibrating the detection signal, the calibration circuit being disposed on a calibration fixture, or on the mounting plate, or on the calibration plate;

[0014] When the calibration circuit is mounted on the calibration fixture, the sensor circuit board further includes a second flexible circuit board. The second flexible circuit board is connected to the base plate and has a calibration circuit interface. During calibration, the calibration fixture is connected to the second flexible circuit board through the calibration circuit interface.

[0015] When the calibration circuit is installed on the calibration board, the calibration board is connected to the base plate through a third flexible circuit board. After the calibration test is completed, the connection between the third flexible circuit board and the base plate is cut off.

[0016] The calibration board has a P layer, and the Q layer in the P layer is a flexible layer. The Q flexible layer is connected to the corresponding layer of the third flexible circuit board in a one-to-one correspondence. Here, P and Q are both positive integers, representing the number of layers of the third flexible circuit board and the calibration board, respectively, and Q≤P.

[0017] In one embodiment, the accelerometer is fixed to the top of the base plate;

[0018] The mounting plate is a mounting plate with a preset concave structure, so that after the mounting plate is fixed to the base plate through the groove, a receiving cavity is formed between the mounting plate and the base plate to accommodate the accelerometer.

[0019] In one embodiment, it further includes a temperature sensor, which is fixed to the bottom of the base plate by a fixing component.

[0020] In one embodiment, the groove provided on the base plate includes a first groove and a second groove;

[0021] The mounting plate has a first connecting end and a second connecting end, wherein the first connecting end is inserted into the first groove and the second connecting end is inserted into the second groove;

[0022] The first connecting end has an L-shaped structure in the thickness direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for engaging with the second groove.

[0023] or;

[0024] The first connecting end has an L-shaped structure in the length direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the length direction for engaging with the second groove.

[0025] In one embodiment, the conditioning circuit includes:

[0026] The filtering circuit connected to the accelerometer is used to filter the sampled signal output by the accelerometer and expand the vibration frequency detection range;

[0027] A signal conversion circuit connected to the filter circuit is used to amplify the output of the filter circuit, or to amplify the output of the filter circuit and convert voltage or current.

[0028] An interface protection circuit for interference suppression is connected to the signal conversion circuit, and the output of the interface protection circuit serves as the output of the conditioning circuit, outputting the processed detection signal.

[0029] In one implementation, it further includes:

[0030] A calibration circuit connected to the accelerometer for calibrating the detection signal, wherein the calibration circuit is an analog calibration circuit based on analog circuitry or a digital calibration circuit based on a controller.

[0031] In one embodiment, the analog calibration circuit includes: a first voltage divider circuit and a second voltage divider circuit;

[0032] The first voltage divider circuit is connected to the scaling factor compensation interface of the accelerometer and is used to adjust the excitation voltage amplitude applied to the differential capacitor of the accelerometer by controlling the voltage of the scaling factor compensation interface, so as to calibrate the sensitivity of the sensor on the sensor circuit board by adjusting the scaling factor of the accelerometer.

[0033] The second voltage divider circuit is connected to the zero-bias compensation interface of the accelerometer and is used to calibrate the operating point of the sensor by adjusting the DC bias of the accelerometer by controlling the voltage of the zero-bias compensation interface.

[0034] In one embodiment, the first voltage divider circuit includes a first voltage divider device and a second voltage divider device;

[0035] The first terminal of the first voltage divider is connected to the first power supply terminal, the second terminal of the first voltage divider is connected to the first terminal of the second voltage divider and the scaling factor compensation interface, and the second terminal of the second voltage divider is grounded.

[0036] The first voltage divider and / or the second voltage divider are voltage dividers with adjustable parameters to control the voltage of the scaling factor compensation interface;

[0037] The second voltage divider circuit includes a third voltage divider device and a fourth voltage divider device. The first terminal of the third voltage divider device is connected to the second power supply terminal. The second terminal of the third voltage divider device is connected to the first terminal of the fourth voltage divider device and the zero bias compensation interface, respectively. The second terminal of the fourth voltage divider device is grounded.

[0038] The third voltage divider and / or the fourth voltage divider are voltage dividers with adjustable parameters to control the voltage of the zero-bias compensation interface.

[0039] In one embodiment, the digital calibration circuit includes a controller connected to the accelerometer, for:

[0040] The value of the first register in the accelerometer is controlled to control the amplification factor of the gain circuit in the accelerometer, so as to calibrate the sensitivity of the sensor on the sensor circuit board.

[0041] The value of the second register in the accelerometer is controlled to control the value of the compensation capacitor connected in parallel to the upper or lower plate static capacitor of the differential capacitor of the accelerometer, so as to perform the operating point calibration of the sensor.

[0042] Secondly, the present invention provides a sensor, including a sensor circuit board with a Z-axis sensing direction as described above.

[0043] Thirdly, the present invention provides a calibration and installation method for a sensor circuit board, the sensor circuit board comprising: an accelerometer for detecting vibration and / or impact of a device under test, with the sensitive direction being the Z-axis; a base plate for supporting the accelerometer; a first flexible circuit board connected to the base plate; a mounting plate provided with a conditioning circuit for receiving sampling signals from the accelerometer through the base plate and the first flexible circuit board, processing the sampling signals through the conditioning circuit, and outputting a processed detection signal; and a calibration plate connected to the base plate through a third flexible circuit board, the calibration plate being provided with a calibration circuit connected to the accelerometer for calibrating the detection signal.

[0044] The calibration and installation method for the sensor circuit board includes:

[0045] After the sensor circuit board is placed horizontally into the calibration fixture, the sensor circuit board is calibrated using the calibration fixture.

[0046] The third flexible circuit board and the calibration plate on the sensor circuit board are removed;

[0047] After the mounting plate is fixed to the base plate through the groove provided on the base plate, the sensor circuit board is placed into the sensor housing.

[0048] In one embodiment, the calibration fixture is a calibration fixture for calibrating a batch of sensor circuit boards;

[0049] After the sensor circuit board is placed horizontally into the calibration fixture, the sensor circuit board is calibrated using the calibration fixture, including:

[0050] After the sensor circuit board is placed horizontally into the calibration fixture, batch calibration of multiple sensor circuit boards is performed using the calibration fixture.

[0051] In one embodiment, before fixing the mounting plate to the base plate via a groove provided on the base plate, the method further includes:

[0052] A stress isolation cover is provided for the accelerometer in the sensor circuit board.

[0053] By applying the technical solution provided in the embodiments of the present invention, through the design of flexible boards, rigid boards, and flexible-rigid combination boards, and by forming a three-dimensional board form through mounting plates and base plates, the installation in the Z-axis sensitive direction can be satisfied, while ensuring the small size of the sensor.

[0054] Specifically, the accelerometer can detect the vibration and / or impact of the device under test, and a base plate is provided to support the accelerometer, meaning the accelerometer can be mounted on the base plate. The base plate can be installed perpendicular to the vibration and impact direction, allowing the sensor of this application to be mounted in the Z-axis sensitive direction. A first flexible circuit board is connected to the base plate, and the mounting plate is equipped with a conditioning circuit. This circuit receives the sampling signal from the accelerometer through the base plate and the first flexible circuit board, processes the sampling signal through the conditioning circuit, and outputs the processed detection signal. This detection signal can effectively reflect the vibration and / or impact of the device under test. Furthermore, the mounting plate has N layers, and layer M of the N layers is a flexible layer. The flexible layer M is connected one-to-one with the corresponding layer of the first flexible circuit board. This design eliminates the need for a special connector when connecting the first flexible circuit board to the mounting plate, which helps to reduce the size of the mounting plate. In addition, since there are grooves on the base plate and the first flexible circuit board can be bent, the mounting plate can be fixed to the base plate through the grooves after installation, thus forming a three-dimensional board. Compared with the traditional design of soldering the accelerometer and peripheral circuits onto a single PCB, the three-dimensional board of this application helps to reduce the size.

[0055] In summary, the sensor of this application supports mounting in the Z-axis sensitive direction and ensures a small sensor size.

[0056] Furthermore, by setting up a calibration circuit to calibrate the detection signal output from the conditioning circuit of the accelerometer's downstream stage, the sensor's sensitivity and operating point can be effectively calibrated. Additionally, if the calibration circuit is placed on a calibration board, the third flexible circuit board can be cut from the base plate after sensor calibration is completed at the manufacturing plant, thus achieving a smaller sensor size. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 A schematic diagram showing different sensitive directions of the accelerometer;

[0059] Figure 2 This is a schematic diagram of the structure of a sensor circuit board for the Z-axis sensing direction provided in a specific embodiment of the present invention;

[0060] Figure 3 This is a schematic diagram of a mounting plate being fixed to a base plate via a groove in one specific embodiment of the present invention;

[0061] Figure 4 The exploded view and cross-sectional view are of a sensor according to a specific embodiment of the present invention;

[0062] Figure 5 The images show a top view and a side view of a sensor circuit board in the Z-axis sensing direction according to a specific embodiment of the present invention.

[0063] Figure 6 This is a schematic diagram of the sensor circuit board in the Z-axis sensing direction provided by a specific embodiment of the present invention during calibration testing;

[0064] Figure 7 This is a schematic diagram of a sensor structure with a second flexible circuit board in one specific embodiment of the present invention;

[0065] Figure 8 This is a schematic diagram of a sensor structure with a temperature sensor in one specific embodiment of the present invention;

[0066] Figure 9 A schematic diagram of the structure of a sensor circuit board in the Z-axis sensing direction provided in another specific embodiment of the present invention;

[0067] Figure 10 This is a schematic diagram of the structure of an analog calibration circuit in a specific embodiment of the present invention;

[0068] Figure 11 This is a schematic diagram of the structure of a digital calibration circuit in a specific embodiment of the present invention;

[0069] Figure 12 This is a schematic diagram of the conditioning circuit in a specific embodiment of the present invention;

[0070] Figure 13 This is a schematic diagram of the conditioning circuit in another specific embodiment of the present invention;

[0071] Figure 14 This is a schematic diagram of the conditioning circuit in another specific embodiment of the present invention;

[0072] Figure 15 This is a schematic diagram of the zero-point output noise of the accelerometer in one specific embodiment;

[0073] Figure 16 This is a schematic diagram comparing vibration bandwidth expansion test results in one specific implementation method;

[0074] Figure 17 This is a schematic diagram of the sensor circuit board layout in one specific embodiment.

[0075] Figure 18This is a flowchart illustrating the calibration and installation method of the sensor circuit board in one specific embodiment of the present invention. Detailed Implementation

[0076] The core of this invention is to provide a sensor, a sensor circuit board for the Z-axis sensitive direction, and a calibration and installation method thereof, while ensuring the small size of the sensor and effectively realizing zero-bias calibration and scaling factor calibration.

[0077] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0078] Please refer to Figure 2 , Figure 2 This is a schematic diagram of a sensor circuit board for the Z-axis sensing direction provided in a specific embodiment of the present invention. The sensor circuit board for the Z-axis sensing direction may include:

[0079] An accelerometer 100 is used to detect vibration and / or shock of the equipment under test, with the sensitive direction being the Z-axis.

[0080] A base plate 201 is used to support the accelerometer 100; the base plate 201 is provided with a groove so that when the installation is completed, the mounting plate 203 is fixed to the base plate 201 through the groove.

[0081] The first flexible circuit board 202 is connected to the base plate 201;

[0082] The mounting plate 203, equipped with a conditioning circuit, has N layers, of which M are flexible layers. Each of the M flexible layers is connected to a corresponding layer of the first flexible circuit board 202. The mounting plate 203 receives sampling signals from the accelerometer 100 via the base plate 201 and the first flexible circuit board 202. The conditioning circuit processes the sampling signals and outputs the processed detection signal. This detection signal effectively reflects the acceleration of the device under test, and thus effectively reflects the vibration and / or impact conditions of the device. Here, M and N are both positive integers, representing the number of layers in the first flexible circuit board 202 and the mounting plate 203, respectively, and M ≤ N.

[0083] In this application, the specific type of accelerometer 100 can be set and adjusted according to actual needs. For example, it can be a capacitive MEMS accelerometer 100, a piezoresistive MEMS accelerometer 100, a resonant MEMS accelerometer 100, etc. In practical applications, the capacitive MEMS accelerometer 100 is more commonly used, with the sensitive direction being the Z-axis.

[0084] The sampling signal output by the accelerometer 100 can reflect the acceleration of the device under test, thereby enabling the analysis of the vibration and impact signals of the device under test based on the acceleration of the device under test. Of course, in other specific situations, the acceleration of the device under test detected by the accelerometer 100 can be used to achieve other functions without affecting the implementation of the present invention.

[0085] To effectively secure the accelerometer 100, this application includes a base plate 201 for supporting the accelerometer 100. The base plate 201 is typically a rigid board, such as a commonly used rigid PCB. The shape of the base plate 201 can be customized as needed, for example... Figure 2 In a specific embodiment, the accelerometer 100 is cuboid and the base plate 201 is circular. In other embodiments, the appropriate base plate shape can be selected as needed, for example, according to the shape of the sensor housing.

[0086] The first flexible circuit board 202 is a flexible circuit board used for circuit routing, thereby sending the sampling signal of the accelerometer 100 to the mounting plate 203. The base plate 201 is connected to the first flexible circuit board 202, and the first flexible circuit board 202 is connected to the mounting plate 203, which is provided with a conditioning circuit.

[0087] Figure 2 For ease of viewing, the mounting plate 203 is not inserted into the base plate 201. In actual applications, please refer to [the documentation / reference] after installation. Figure 3 This is a schematic diagram of a mounting plate 203 fixed to a base plate 201 via a groove in a specific embodiment of the present invention. Since the first flexible circuit board 202 is a flexible board and can be bent, the mounting plate 203 can be fixed to the base plate 201 via the groove provided on the base plate 201, thus forming a three-dimensional sensor structure. Compared with the traditional design of soldering the accelerometer 100 and peripheral circuits onto a single PCB, this three-dimensional board form helps to reduce the size.

[0088] Furthermore, the solution in this application takes into account that the first flexible circuit board 202 is a flexible board. If the mounting plate 203 is set as a rigid board, then the contact part between the first flexible circuit board 202 and the mounting plate 203 needs to be set with a special interface, which is not conducive to reducing the size and is also easy to be damaged due to bending. In this regard, the solution in this application adopts a rigid-flex board design for the mounting plate 203, that is, the first flexible circuit board 202 is an M-layer flexible board, and the mounting plate 203 has N layers, where M≤N, and the M layer in the N layers is a flexible layer, so that the M flexible layers in the mounting plate 203 can be connected one-to-one with the corresponding layers of the first flexible circuit board 202.

[0089] In practical applications, the first flexible circuit board 202 is typically a flexible board with flexural strength, high temperature resistance, and high insulation. Its thickness is generally less than 0.2mm, and it is usually configured as one or two layers. It can typically be connected to the top or bottom of the mounting plate 203. For example, in one scenario, M=2, meaning the first flexible circuit board 202 is a two-layer flexible board. These two layers of the first flexible circuit board 202 can be connected to the first and second layers of the mounting plate 203, respectively. Both the first and second layers of the mounting plate 203 are flexible layers, with the first layer of the mounting plate 203 being its top layer. Alternatively, these two layers of the first flexible circuit board 202 can be connected to the penultimate and penultimate layers of the mounting plate 203, respectively. In this case, the penultimate and penultimate layers of the mounting plate 203 are flexible layers, with the penultimate layer of the mounting plate 203 being its bottom layer. Of course, besides connecting to the top or bottom of the mounting plate 203, in other embodiments, a suitable M layer from the N layers can be selected as the flexible layer and connected one-to-one with the corresponding layers of the first flexible circuit board 202, as needed.

[0090] In summary, because the mounting plate 203 adopts the above-mentioned rigid-flex board design, the mounting plate 203 does not need to be equipped with a special interface and can be directly connected to the first flexible circuit board 202. Moreover, the connection is not easily damaged due to bending, thus ensuring reliability.

[0091] In practical applications, sensors typically require a sensor housing. Figure 2 and Figure 3 The outer casing is not shown in the text; please refer to [reference needed]. Figure 4 , Figure 4 These are exploded views and cross-sectional views of a sensor in one specific embodiment. Figure 3 It can be seen that the mounting surface of the inner cavity of the sensor housing can effectively cooperate with the base plate 201 to fix the base plate 201 inside the sensor housing. Figure 4 The outer shell includes an upper shell and a lower shell that mates with it. In other embodiments, other outer shell structures may be used as needed without affecting the implementation of the present invention.

[0092] The specific shape of the mounting plate 203 can be set and adjusted according to actual needs. In practical applications, considering that the mounting plate 203 needs to be inserted into the groove on the base plate 201, and the accelerometer 100 is mounted on the base plate 201, in order to effectively utilize space and reduce the sensor size, after the mounting plate 203 is inserted into the groove of the base plate 201, the side of the mounting plate 203 near the base plate 201 can usually be an arch shape or other shapes that facilitate insertion into the base plate 201 without affecting the position of the accelerometer 100. As can be seen in the above embodiments of this application. Figure 2 and Figure 3 The mounting plates 203 are all in the shape of an arch bridge, that is, they are inserted into the grooves of the base plate 201 through square columns with steps on both sides.

[0093] Furthermore, in practical applications, when the mounting plate 203 is inserted into the groove of the base plate 201, the side away from the base plate 201 can usually be set in a convex shape to facilitate the placement of a stress isolation cover. The stress isolation cover can prevent the sensor housing from transmitting excessive stress to the accelerometer 100 on the base plate 201, thus helping to avoid stress interference to the accelerometer 100. It also provides electrical isolation, improving the insulation between the mounting plate 203 and the sensor housing. Figure 4 The annular stress isolation shield 40 is shown in the image.

[0094] See also Figure 5 The figures are a top view and a side view of a sensor circuit board in one specific embodiment. It is understood that the mounting plate 203 has not yet been inserted into the groove of the base plate 201, and therefore the installation is not yet complete. Figure 5 The mounting plate 203 also features elongated holes 50, which provide a degree of stress and electrical isolation. The specific number and size of these holes 50 can be customized as needed. Furthermore, Figure 5 The image also shows three triangular mounting holes on the base plate 201 for fixing the accelerometer 100.

[0095] While some traditional accelerometers boast high integration, they typically operate on 1.8V to 5V power supplies, making them unsuitable for direct connection to industrial control or fault detection system input interfaces and lacking calibration functionality. Although some accelerometers are factory-calibrated, downstream sensor application manufacturers often introduce zero-bias errors during installation due to factors such as surface mount angles and soldering temperature stress, causing variations in the 0g zero-point output. Furthermore, while sensor application manufacturers usually add hardware adjustment circuitry to the accelerometer's subsequent circuitry, allowing for calibration of individual accelerometers within a certain range, the accuracy and efficiency of this calibration are generally low. Even the subsequent adjustment circuitry can introduce errors, leading to lower sensor sensitivity and more severe operating point drift.

[0096] In one specific embodiment of the present invention, it may further include: a calibration circuit connected to the accelerometer 100 for calibrating the detection signal output by the conditioning circuit of the accelerometer 100, that is, calibrating the sensor on the sensor circuit board through the calibration circuit.

[0097] The calibration circuit can be set on the calibration fixture, or on the mounting plate 203, or on the calibration plate 204;

[0098] When the calibration circuit is set on the calibration fixture, the calibration fixture is connected to the base plate 201 through the second flexible circuit board during calibration. The second flexible circuit board is provided with a calibration circuit interface. During calibration, the calibration fixture is connected to the second flexible circuit board through the calibration circuit interface.

[0099] When the calibration circuit is set on the calibration board 204, the calibration board 204 is connected to the base plate 201 through the third flexible circuit board 205. After the calibration test is completed, the connection between the third flexible circuit board 205 and the base plate 201 is cut off, that is, the third flexible circuit board 205 and the base plate 201 are cut off, and the two components are separated from the physical connection.

[0100] The calibration board 204 has a P layer, and the Q layer in the P layer is a flexible layer. The Q flexible layer is connected one-to-one with the corresponding layer of the third flexible circuit board 205. Here, P and Q are both positive integers, representing the number of layers of the third flexible circuit board 205 and the calibration board 204, respectively, and Q≤P.

[0101] This implementation effectively calibrates the output of the sensor circuit board, i.e., the conditioning circuit, through the calibration circuit, thereby improving sensor sensitivity and calibrating the sensor's operating point. Furthermore, this implementation considers flexibility; the calibration circuit can be placed on a calibration fixture, a mounting plate 203, or a calibration plate 204, depending on actual needs. When the calibration circuit is placed on the calibration plate 204, since the sensor calibration can be completed in the manufacturing plant, the third flexible circuit board 205 can be cut from the base plate 201 before installation, thus achieving a smaller sensor size.

[0102] See also Figure 6 This is a schematic diagram of the sensor circuit board in the Z-axis sensing direction during calibration testing in a specific embodiment. Figure 6 In this embodiment, the calibration circuit is mounted on the calibration board 204. The calibration board 204 in this embodiment is a rigid-flex board, while the third flexible circuit board 205 is a flexible board. The Q layer in the P layer of the calibration board 204 is a flexible layer, which is connected one-to-one with the corresponding layer of the third flexible circuit board 205. This facilitates the connection between the calibration board 204 and the third flexible circuit board 205 and also helps reduce the size of the calibration board 204. Of course, since the calibration of the sensor circuit board only needs to be performed during sensor assembly or after the sensor circuit board is manufactured, the calibration circuit is not needed when the sensor circuit board (or sensor) is used after calibration. Therefore, to save space and reduce the size of the sensor, the physical connection between the third flexible circuit board 205 and the base plate 201 can be severed after calibration testing. This means that during installation, the calibration board 204 and the third flexible circuit board 205 do not need to be installed in the sensor housing. This means that the calibration board 204 and the third flexible circuit board 205 are only needed during calibration testing, and can be removed by a depaneling machine after calibration testing without affecting the size of the sensor. The above text Figure 3 , Figure 4 as well as Figure 5 In the example, the calibration plate 204 and the third flexible circuit board 205 are not shown. This can represent an implementation where the calibration circuit is mounted on the mounting plate 203, thus eliminating the need for the calibration plate 204 and the third flexible circuit board 205. Alternatively, it can represent an implementation where, although the calibration plate 204 and the third flexible circuit board 205 are present, the calibration test has already been completed, and the calibration plate 204 and the third flexible circuit board 205 have been removed. Therefore, in the completed installation state, the calibration plate 204 and the third flexible circuit board 205 will not be present.

[0103] See also Figure 7 This is a schematic diagram of a sensor structure with a second flexible circuit board. Figure 7In this embodiment, the calibration circuit is mounted on the calibration fixture. During calibration, the calibration fixture is connected to the base plate 201 via the second flexible circuit board 206, meaning the second flexible circuit board 206 needs to be connected to the base plate 201. In this implementation, the calibration circuit is mounted on the calibration fixture, and the second flexible circuit board 206 has a calibration circuit interface, thereby achieving a circuit connection between the calibration circuit on the calibration fixture and the sensor circuit board. It is understood that when the sensor circuit board is removed from the calibration fixture after calibration, the connection between the calibration fixture and the second flexible circuit board 206 is also disconnected. Since the second flexible circuit board 206 is a flexible board, after calibration testing, during installation, a certain space can be left in the sensor housing to accommodate the second flexible circuit board 206, thus eliminating the need to cut it off after calibration testing. Of course, even if the second flexible circuit board 206 is a flexible board and occupies little space, it will still occupy a certain amount of space. Therefore, in practical applications, in situations where the sensor size requirements are more stringent, the implementation method described above, which sets the calibration circuit on the calibration board 204, is usually adopted. That is, the calibration board 204 and the third flexible circuit board 205 are removed by cutting with a board splitting machine.

[0104] In some implementations, the calibration circuit can be directly mounted on the mounting plate 203. The advantage is that no cutting operation is required, but it will increase the area of ​​the mounting plate 203 to a certain extent. It can usually be used in situations where the sensor size requirement is not particularly high.

[0105] In one specific embodiment of the present invention, the accelerometer 100 is fixed to the top of the base plate 201;

[0106] The mounting plate 203 is a mounting plate 203 with a preset concave structure, so that after the mounting plate 203 is fixed on the base plate 201 through the groove, a receiving cavity is formed between the mounting plate 203 and the base plate 201 to accommodate the accelerometer 100.

[0107] The sensor also includes a temperature sensor, which is fixed to the bottom of the base plate 201 by a fixing component.

[0108] This embodiment takes into account that in some applications, sensors need to detect both acceleration and temperature. Therefore, in this embodiment, the accelerometer 100 can be fixed to the top of the base plate 201, and a temperature sensor is also provided, which is fixed to the bottom of the base plate 201 by a fixing component. See also... Figure 8 This is a schematic diagram of a sensor structure with a temperature sensor in one specific embodiment. Figure 8 and Figure 4The temperature sensor 80 is shown in the diagram. Specifically, the temperature sensor 80 can be a temperature-measuring component such as a platinum resistance thermometer, thermocouple, or digital temperature sensor. It should also be noted that the temperature sensor 80 is fixed to the bottom of the base plate 201 by a fixing component, rather than being directly fixed to the bottom of the base plate 201. This is because, in practical applications, the preset temperature measurement location and the preset acceleration measurement location are usually some distance apart. Furthermore, this also helps to avoid interference from high / low temperatures on the accelerometer 100. Figure 8 In this case, the temperature sensor 80 is specifically fixed to the bottom of the base plate 201 by three cylindrical fixing parts.

[0109] In this embodiment, the mounting plate 203 has a pre-defined concave structure, such as the arch bridge shape described above. This concave structure is located on a designated side near the base plate 201. After the mounting plate 203 is fixed to the base plate 201 via the groove, the presence of this concave structure creates a receiving cavity between the mounting plate 203 and the base plate 201, which can accommodate the accelerometer 100, thereby effectively utilizing space and reducing the sensor size.

[0110] In one specific embodiment of the present invention, the groove provided on the base plate 201 includes a first groove and a second groove;

[0111] Mounting plate 203 has a first connecting end and a second connecting end, wherein the first connecting end is inserted into a first groove and the second connecting end is inserted into a second groove;

[0112] The first connecting end has an L-shaped structure in the thickness direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for engaging with the second groove.

[0113] or;

[0114] The first connecting end has an L-shaped structure in the length direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the length direction for engaging with the second groove.

[0115] In this embodiment, in order to ensure stability, the base plate 201 can have multiple grooves. For example, in this embodiment, it specifically includes a first groove and a second groove. Correspondingly, the mounting plate 203 needs to have a corresponding first connecting end and a second connecting end, so that it can be inserted into the first groove and the second groove respectively.

[0116] Furthermore, this implementation takes into account that the mortise and tenon structure helps ensure the reliability of the connection; therefore, an L-shaped structure can be used to achieve the mortise and tenon connection. For example, see the documentation for the first connection end. Figure 5The side view shows the first connecting end circled in an ellipse. From the side view, it can be seen that... Figure 5 In this embodiment, the first connecting end has an L-shaped structure in the thickness direction for mating with the first groove. That is, the portion of the first connecting end inserted into the first groove is narrower, while the portion not inserted into the first groove is wider, forming an L-shaped structure, or stepped structure, which helps ensure the reliability of the connection. Furthermore, Figure 8 This implementation method was also adopted, and Figure 8 The image shows the state after the mounting plate 203 has been inserted into the base plate 201. Figure 8 It can also be seen that the first connecting end has an L-shaped structure in the thickness direction for engaging with the first groove.

[0117] Taking the first connection end as an example, please refer to... Figure 7 ,For example Figure 7 The first connection end is circled in an ellipse. It can be seen that... Figure 7 In one embodiment, the first connecting end has an L-shaped structure in the length direction for engaging with the first groove. After the L-shaped structure is inserted into the first groove, it helps to ensure the reliability of the connection. Figure 9 It is adopted Figure 7 The implementation method is in the state after installation is complete. Figure 9 The first connecting end is also circled in the image. It can be seen that the first connecting end has an L-shaped structure in the length direction for engaging with the first groove.

[0118] The installation location of the calibration circuit has been described in the above embodiments. Its specific circuit structure can be of various types, as long as it can cooperate with the accelerometer 100 to achieve calibration. For example, in a specific embodiment of the present invention, it may include: a calibration circuit connected to the accelerometer 100 for calibrating the detection signal output by the conditioning circuit. The calibration circuit is an analog calibration circuit based on analog circuit calibration, or a digital calibration circuit based on controller calibration.

[0119] This implementation takes into account that the calibration circuit can be implemented by either analog or digital calibration circuits, ensuring flexibility in implementation. Of course, the specific implementation of the analog and digital calibration circuits can be determined according to actual needs, such as based on the design of the accelerometer 100.

[0120] For example, in one specific embodiment of the present invention, the analog calibration circuit may include: a first voltage divider circuit and a second voltage divider circuit;

[0121] The first voltage divider circuit is connected to the scale factor compensation interface of the accelerometer 100. It is used to adjust the excitation voltage amplitude applied to the differential capacitor of the accelerometer 100 by controlling the voltage of the scale factor compensation interface, so as to calibrate the sensitivity of the sensor on the sensor circuit board by adjusting the scale factor calibration of the accelerometer 100.

[0122] The second voltage divider circuit is connected to the zero-bias compensation interface of the accelerometer 100. It is used to calibrate the zero bias of the accelerometer 100 by adjusting the DC bias of the accelerometer 100 by controlling the voltage of the zero-bias compensation interface, so as to calibrate the operating point of the sensor.

[0123] The scaling factor of an accelerometer 100, also known as acceleration sensitivity, is the ratio of the output of the acceleration sensing axis to the input acceleration. Zero bias, also called bias value, is the DC output of the accelerometer at an acceleration of 0g, determining the sensor's operating point. The unit is usually mg or the corresponding electrical output value. Zero bias affects the sensor's static operating point, that is, it affects the sensor's static output voltage value (usually in V).

[0124] Because the accelerometer 100 itself may have accuracy issues, and the process of soldering it onto the circuit board can affect its sensitivity and zero bias, which in turn affects the output of the conditioning circuit, ultimately impacting the sensor's sensitivity and operating point. Therefore, to improve the sensor's sensitivity and operating point, the output of the conditioning circuit needs to be calibrated, which means calibrating the sensitivity and operating point of the sensor on the circuit board.

[0125] This implementation takes into account that the excitation voltage amplitude of the differential capacitor of the accelerometer 100 affects the scale factor of the accelerometer 100. Therefore, the scale factor of the accelerometer 100 can be adjusted by adjusting the excitation voltage amplitude applied to the differential capacitor. The excitation voltage amplitude of the differential capacitor of the accelerometer 100 can be adjusted by the voltage of the scale factor compensation interface. Therefore, in this implementation, by connecting the first voltage divider circuit to the scale factor compensation interface of the accelerometer 100 and controlling the voltage of the scale factor compensation interface, the scale factor of the accelerometer 100 can be adjusted. Furthermore, it is understood that when adjusting the scale factor of the accelerometer 100, the sensitivity of the output of the conditioning circuit needs to be detected. That is, by adjusting the scale factor of the accelerometer 100, the sensitivity of the output of the conditioning circuit is adjusted, thereby calibrating the sensitivity of the output of the conditioning circuit, which in turn calibrates the sensor. When this implementation method is adopted, the accelerometer 100 needs to be pre-configured according to the functional requirements of this application so that the accelerometer 100 has the scaling factor compensation interface required by this application, and the excitation voltage amplitude applied to the differential capacitor of the accelerometer 100 can be adjusted based on the voltage of the scaling factor compensation interface.

[0126] Furthermore, this implementation takes into account that, in addition to the scaling factor, the accelerometer 100 may also have a zero bias due to its own characteristics or the installation process. Therefore, this implementation can also adjust the zero bias of the accelerometer 100, thereby calibrating the operating point of the conditioning circuit output, which in turn calibrates the operating point of the sensor. Specifically, in this implementation, the second voltage divider circuit is connected to the zero bias compensation interface of the accelerometer 100, thereby controlling the voltage of the zero bias compensation interface. This allows adjustment of the DC bias of the accelerometer 100, achieving zero bias adjustment of the accelerometer 100, thereby calibrating the operating point of the conditioning circuit output, i.e., calibrating the operating point of the sensor. It is understood that when using this implementation, the accelerometer 100 needs to be pre-configured according to the functional requirements of this application, so that the accelerometer 100 has the zero bias compensation interface required by this application, and the DC bias of the accelerometer 100 can be adjusted based on the voltage of the zero bias compensation interface to achieve zero bias adjustment of the accelerometer 100.

[0127] The specific structures of the first and second voltage divider circuits can be set as needed, as long as they can achieve voltage control of the corresponding interfaces. For example, see [reference needed]. Figure 10This is a schematic diagram of the structure of an analog calibration circuit in a specific embodiment. The first voltage divider circuit may include a first voltage divider device and a second voltage divider device. The first terminal of the first voltage divider device is connected to the first power supply terminal Vref1, the second terminal of the first voltage divider device is connected to the first terminal of the second voltage divider device and the scaling factor compensation interface, and the second terminal of the second voltage divider device is grounded.

[0128] The first voltage divider and / or the second voltage divider are voltage dividers with adjustable parameters to control the voltage of the scaling factor compensation interface;

[0129] The second voltage divider circuit includes a third voltage divider device and a fourth voltage divider device. The first terminal of the third voltage divider device is connected to the second power supply terminal Vref2. The second terminal of the third voltage divider device is connected to the first terminal of the fourth voltage divider device and the zero bias compensation interface, respectively. The second terminal of the fourth voltage divider device is grounded.

[0130] The third and / or fourth voltage divider devices are voltage divider devices with adjustable parameters to control the voltage of the zero bias compensation interface.

[0131] In this implementation, the first voltage divider circuit consists of a first voltage divider device and a second voltage divider device, which has a simple structure. The first voltage divider device and / or the second voltage divider device need to be voltage divider devices with adjustable parameters, so that the voltage of the scaling factor compensation interface can be controlled. For example Figure 10 In the specific implementation, the first voltage divider device is denoted as R11, which can be a fixed resistor or a resistor with an adjustable resistance value, the second voltage divider device is a variable resistor diode D11, and the scaling factor compensation interface is denoted as Vsens.

[0132] Similarly, the second voltage divider circuit consists of a third and a fourth voltage divider device. It has a simple structure, and the third and / or fourth voltage divider devices need to be adjustable in their own parameters to control the voltage at the zero-bias compensation interface. For example... Figure 10 In the specific implementation, the third and fourth voltage dividers are denoted as R12 and R13, respectively, and the zero-bias compensation interface is denoted as Vbisa. One or both of the third and fourth voltage dividers are adjustable resistors, thus controlling the voltage of the zero-bias compensation interface. Furthermore, in practical applications, voltage division based on a variable resistor D11 typically offers higher accuracy than that based on an adjustable resistor.

[0133] In one specific embodiment of the present invention, see [reference needed]. Figure 11 The digital calibration circuit includes a controller 101, which is connected to the accelerometer 100 and is used for:

[0134] The value of the first register in the accelerometer 100 is controlled so as to control the amplification factor of the gain circuit in the accelerometer 100, thereby calibrating the sensitivity of the sensor on the sensor circuit board.

[0135] The value of the second register in the accelerometer 100 is controlled to control the value of the compensation capacitor of the upper or lower plate static capacitor connected in parallel to the differential capacitor of the accelerometer 100, so as to perform sensor operating point calibration.

[0136] In this implementation, a controller 101 is used for digital calibration. The controller 101 is typically an MCU. Specifically, considering that the accelerometer 100 has multiple gain circuits, the output voltage of the circuit can be amplified or reduced by controlling the amplification factor of these gain circuits through the value of the first register, thereby adjusting the scale factor. Therefore, in this implementation, the controller 101 adjusts the scale factor of the accelerometer 100 by controlling the value of the first register, thus achieving sensitivity calibration of the sensor located on the sensor circuit board. In practical applications, the gain circuit is adjustable from 1 to 256 times, set in 1-byte increments.

[0137] The accelerometer 100 is equipped with multiple sets of differential capacitors. These capacitors can be connected in parallel to the upper plate static capacitor or the lower plate static capacitor of the accelerometer 100 meter head. The compensation capacitor value of the upper plate static capacitor or the lower plate static capacitor connected in parallel to the differential capacitor of the accelerometer 100 can be controlled by the value of the second register. The zero bias adjustment of the accelerometer 100 can be achieved by adjusting the static capacitor, thereby realizing the working point calibration of the sensor.

[0138] Furthermore, it should be noted that when calibrating the accelerometer 100 via the controller 101, voltage control can also be applied to the scale factor compensation interface and the zero bias compensation interface to calibrate the sensor located on the sensor circuit board. For example... Figure 11In this embodiment, the controller 101 connects not only to the accelerometer 100 via SPI interfaces (MCLK and MOSI), but also to the scale factor compensation interface (Vsens) and the bias compensation interface (Vbias) via DAC0 and DAC1 interfaces. In practical applications, this method typically achieves coarse calibration by controlling the voltage of the scale factor compensation interface and the bias compensation interface, while fine calibration is achieved by controlling the values ​​of the first and second registers. In other embodiments, one of the scale factor compensation interface (Vsens) and the bias compensation interface (Vbias) can be controlled by the controller 101, while the other can be set to a fixed voltage value or controlled by an analog calibration circuit. That is, if needed, a combination of analog and digital calibration circuits can be used to achieve calibration; this application does not limit this. For example, as described below... Figure 14 In this implementation, the voltage of the zero bias compensation interface (Vbias) is controlled by the third voltage divider R12 and the fourth voltage divider R13, the voltage of the scaling factor compensation interface (Vsens) is fixed, and the accelerometer 100 is calibrated using the controller 101. Figure 14 Controller 101 is not shown.

[0139] As described above, the calibration circuit can be located on the second flexible circuit board 206, the mounting plate 203, or the calibration board 204. Therefore, if an analog calibration circuit design is used, the calibration circuit can be located on either the second flexible circuit board 206 or the mounting plate 203. If a digital calibration circuit design is used, and the digital calibration circuit is located on either the second flexible circuit board 206 or the mounting plate 203, the relevant calibration parameters can be stored in the digital calibration circuit after calibration, for example, specifically in the MCU's flash memory. However, if the digital calibration circuit is located on the calibration board 204, since the calibration board 204 will be removed after calibration, the relevant calibration parameters obtained through calibration need to be stored in the accelerometer 100, for example, in the accelerometer 100's OTP (a non-volatile storage area). In this case, the voltages of the accelerometer 100's scale factor compensation interface and zero bias compensation interface are usually set to fixed values, for example... Figure 13 In this implementation, such a design is adopted: the voltages of the scale factor compensation interface and the zero bias compensation interface of the accelerometer 100 are fixed. At this point, the controller can be placed on the calibration board 204. After calibration is completed, the calibration board 204 is removed, effectively reducing the sensor's size and improving reliability. Furthermore, Figure 12 The controller 101 is not shown in the diagram.

[0140] The sampling signal sent by the accelerometer 100 needs to be transmitted to the conditioning circuit of the mounting plate 203 for processing. The processed signal is then used as the detection signal obtained by the sensor. The specific circuit configuration of the conditioning circuit can be set according to actual needs. For example, voltage amplification and current-voltage conversion can usually be performed through the conditioning circuit.

[0141] In one specific embodiment of the present invention, see [reference needed]. Figure 12 This is a schematic diagram of the structure of a conditioning circuit in one specific embodiment. The conditioning circuit may include:

[0142] The filter circuit 301 connected to the accelerometer 100 is used to filter the sampling signal output by the accelerometer 100 and expand the vibration frequency detection range.

[0143] The signal conversion circuit 302, which is connected to the filter circuit 301, is used to amplify the output of the filter circuit, or to amplify the output of the filter circuit 301, and to convert voltage or current.

[0144] The interface protection circuit 303, connected to the signal conversion circuit 302, is used for anti-interference, and the output of the interface protection circuit 303 is the detection signal obtained after the output processing of the conditioning circuit.

[0145] This implementation takes into account that the accelerometer 100 has a resonant peak output. The bandwidth of a traditional accelerometer 100 is one-third of the resonant frequency. Some accelerometers 100, in order to balance sensitivity and noise, have a natural frequency design of less than 30kHz, which cannot meet the requirement of a bandwidth of over 10kHz. In this implementation, a filter circuit 301 is connected to the output of the accelerometer 100 for filtering, typically a first-order RC low-pass filter circuit. This not only filters out high-frequency noise but also suppresses the resonant peak, thereby expanding the bandwidth of the accelerometer 100, effectively extending the vibration frequency detection range.

[0146] Figure 12 The diagram also shows a calibration circuit 304 and a power supply circuit 305 connected to the accelerometer 100. The power supply circuit 305 is connected to the calibration circuit 304, the signal conversion circuit 302, and the accelerometer 100, respectively, thereby providing power to the devices / lines in the calibration circuit 304, the signal conversion circuit 302, and the accelerometer 100 that require power. Different devices / lines may require different voltage levels. Furthermore, since the filter circuit 301 uses a passive filter circuit, therefore... Figure 12 In this embodiment, the power supply circuit 305 is not connected to the filter circuit 301. In other embodiments, an active filter circuit can be used as needed and the power supply circuit 305 can provide the required power.

[0147] See also Figure 13 This is a schematic diagram of the conditioning circuit in another specific embodiment. Figure 13 In this embodiment, the output of the accelerometer 100 is Vmems, and the filter circuit 301 specifically adopts a first-order RC low-pass filter circuit, with the resistor and capacitor in the first-order RC low-pass filter circuit denoted as R0 and C0, respectively. Furthermore, in some embodiments, the resistor in the first-order RC low-pass filter circuit can also be integrated inside the accelerometer 100.

[0148] The signal conversion circuit 302 can amplify the output of the filter circuit 301. Alternatively, it can not only amplify the output of the filter circuit 301 but also perform voltage or current conversion. It can be designed as a current output sensor or a voltage output sensor, depending on the actual needs. Figure 13 In this circuit, the signal conversion circuit 302 consists of one operational amplifier and two resistors, which amplifies the output of the filter circuit 301, making it a voltage output type sensor. Meanwhile... Figure 14 In the example, the signal conversion circuit 302 consists of an operational amplifier, a resistor, and a switching transistor. It can convert voltage signals into current signals and amplify the output of the filter circuit 301.

[0149] The interface protection circuit 303 has various structures, for example, it can use... Figure 13 The transient voltage suppression diode RV1 is used to achieve this, resulting in a simple structure and low cost. The output of the interface protection circuit 303... Figure 13 It is denoted as Vout in Chinese. Furthermore... Figure 13 and Figure 14 The power supply circuit is shown above the signal conversion circuit 302 in the middle, which can realize the power supply of the circuit. In other specific embodiments, the specific structure of the power supply circuit can be set as needed.

[0150] By applying the technical solution provided in the embodiments of the present invention, through the design of flexible circuit boards and rigid-flex boards, and by forming a three-dimensional board form through mounting plates and base plates, the installation in the Z-axis sensitive direction can be satisfied, while ensuring the small size of the sensor.

[0151] Specifically, the accelerometer can detect the vibration and / or impact of the device under test, and a base plate is provided to support the accelerometer, meaning the accelerometer can be mounted on the base plate. The base plate can be installed perpendicular to the vibration and impact direction, allowing the sensor of this application to be mounted in the Z-axis sensitive direction. A first flexible circuit board is connected to the base plate, and the mounting plate is equipped with a conditioning circuit. This circuit receives the sampling signal from the accelerometer through the base plate and the first flexible circuit board, processes the sampling signal through the conditioning circuit, and outputs the processed detection signal. This detection signal can effectively reflect the vibration and / or impact of the device under test. Furthermore, the mounting plate has N layers, and layer M of the N layers is a flexible layer. The flexible layer M is connected one-to-one with the corresponding layer of the first flexible circuit board. This design eliminates the need for a special connector when connecting the first flexible circuit board to the mounting plate, which helps to reduce the size of the mounting plate. In addition, since there are grooves on the base plate and the first flexible circuit board can be bent, the mounting plate can be fixed to the base plate through the grooves after installation, thus forming a three-dimensional board. Compared with the traditional design of soldering the accelerometer and peripheral circuits onto a single PCB, the three-dimensional board of this application helps to reduce the size.

[0152] In summary, the sensor of this application supports mounting in the Z-axis sensitive direction and ensures a small sensor size.

[0153] In one specific embodiment of the practical application, the overall circuit board size of this application meets the requirements of a diameter less than or equal to 12.5 mm and a height less than 16 mm, which can satisfy the installation requirements of miniaturized sensors (sensor diameter less than or equal to 18.5 mm). After installation, the sensor exhibits good vibration and shock response, with a vibration sensitivity distribution range of 99.05% to 102.22% of 20 mV / g, and an shock SV value detection range of 0 to 10000 SV.

[0154] by Figure 13 For example, in one implementation, the host computer can control the controller 101 via a serial port or digital bus. The controller 101 can then set the register values ​​in the accelerometer 100. The value of the first register sets the PGA gain switch, controlling the amplification factor of the gain circuit in the accelerometer 100 and adjusting the scale factor, for example, in a step of 0.025mV / g with an adjustment range of 10mV / g ± 10mV / g. The value of the second register compensates for the static differential capacitor value, thereby adjusting the zero-point output of the accelerometer 100, for example, in a step of 25mV with an adjustment range of 2.5V ± 1.5V.

[0155] For example, in one scenario, the sensor requires an output operating point of 5V and a sensitivity of 20mV / g. The register parameters of the accelerometer 100 can then be set via the controller 101 to calibrate the zero bias to 2.5V ± 0.025V and the scale factor to 10mV / g ± 0.025mV / g. Figure 13 The signal conversion circuit in the conditioning circuit is specifically set as a non-inverting amplifier with a 2x amplification. Therefore, the output operating point of the sensor is 5V±0.05V, and the sensitivity is 20mV / g±0.05mV / g, ensuring that the sensor output accuracy is less than or equal to 1%.

[0156] See also Figure 15 This is a schematic diagram of the accelerometer zero-point output noise in one specific implementation. Figure 15 In the test, the zero-point output noise of the accelerometer 100 was about 0.4mVpp, and the zero-point output was stable for a long time at 0g. By configuring the register through the digital calibration circuit, the sensor achieved an accurate output of 5.0196V (+1g) at the operating point and 20mV / g at the sensitivity.

[0157] See also Figure 16 When traditional accelerometers have a resonant peak output and the vibration bandwidth cannot reach 10kHz, the 10kHz amplitude-frequency response error of the accelerometer 100 can be adjusted from +4.25dB to 0.13dB by the filter circuit 301 in the conditioning circuit in this embodiment of the application. Figure 16 The diagram above shows the amplitude-frequency response before setting the first-order RC filter circuit, and the diagram below shows the amplitude-frequency response after setting the first-order RC filter circuit. It can be seen that the first-order RC filter circuit reduces the 10kHz amplitude-frequency response error from about 30% to less than 4%.

[0158] Corresponding to the above embodiments of the sensor circuit board with Z-axis sensing direction, this embodiment of the invention also provides a sensor, which may include the sensor circuit board with Z-axis sensing direction as in any of the above embodiments, and can be referred to in correspondence with the above.

[0159] This invention also provides a calibration and installation method for a sensor circuit board, the sensor circuit board comprising: an accelerometer for detecting vibration and / or impact of a device under test, with the sensitive direction being the Z-axis; a base plate for supporting the accelerometer; a first flexible circuit board connected to the base plate; a mounting plate provided with a conditioning circuit for receiving sampling signals from the accelerometer through the base plate and the first flexible circuit board, processing the sampling signals through the conditioning circuit, and outputting the processed detection signal; and a calibration plate connected to the base plate through a third flexible circuit board, the calibration plate being provided with a calibration circuit connected to the accelerometer for calibrating the detection signal.

[0160] See also Figure 18 The calibration and installation method for this sensor circuit board may include the following steps:

[0161] Step S101: After placing the sensor circuit board horizontally into the calibration fixture, calibrate the sensor circuit board using the calibration fixture.

[0162] Step S102: Cut off the third flexible circuit board and calibration board on the sensor circuit board;

[0163] Step S103: After fixing the mounting plate to the base plate through the groove provided on the base plate, place the sensor circuit board into the sensor housing.

[0164] This implementation takes into account that when calibrating the sensor circuit board of the present application, the sensor circuit board can be placed horizontally into the calibration fixture, and then the sensor circuit board can be calibrated through the calibration fixture. The calibration circuit set in the sensor circuit board can be the analog calibration circuit or digital calibration circuit described above. The calibration principle can be referred to the description above, and will not be repeated here.

[0165] In this embodiment, the calibration circuit is mounted on a calibration board, which is connected to the base plate via a third flexible circuit board. After calibration, the third flexible circuit board and the calibration board on the sensor circuit board can be removed, i.e., the connection between the third flexible circuit board and the base plate can be severed. This allows the sensor circuit after calibration to have a small size, thus ensuring a small sensor size.

[0166] It should also be noted that for schemes using a second flexible circuit board, calibration can also be performed using a calibration fixture.

[0167] The calibration fixture can be a calibration fixture used for calibrating a batch of sensor circuit boards. Step S101 may specifically include:

[0168] After the sensor circuit boards are placed horizontally into the calibration fixture, batch calibration of multiple sensor circuit boards is performed using the calibration fixture.

[0169] In this implementation, to improve calibration efficiency, multiple sensor circuit boards can be horizontally placed within the calibration fixture, and batch calibration can be performed simultaneously through the calibration interface, which helps improve calibration efficiency and pass rate. For example, if motion control of the calibration fixture is required during calibration, the corresponding sensor circuit boards can be calibrated one by one. See also... Figure 17This diagram illustrates the panel layout of a sensor circuit board in one specific embodiment. The left side shows a configuration with a calibration plate, while the right side shows a configuration with a second flexible circuit board. As described above, in this application, calibration is not performed separately after the accelerometer is manufactured. Instead, the accelerometer, base plate, mounting plate, and other circuit boards are connected together. That is, after the sensor circuit board is generated and connected, it is horizontally placed into the calibration fixture for calibration, thus calibrating the entire sensor circuit board together, improving calibration accuracy. The calibration process can involve calibrating a single sensor circuit board individually, or simultaneously calibrating multiple circuit boards using a calibration fixture. This embodiment illustrates the panel layout of the sensor circuit boards, allowing for batch horizontal calibration of multiple sensor circuit boards using a calibration fixture.

[0170] Furthermore, before assembling the sensor circuit board, that is, before fixing the mounting plate to the base plate through the groove provided on the base plate, a stress isolation cover can be set for the accelerometer in the sensor circuit board. Then, the mounting plate 203 and the base plate 201 of the sensor circuit board are assembled and placed into the sensor housing together.

[0171] As described above, when the mounting plate 203 is inserted into the groove of the base plate 201, the side away from the base plate 201 can typically be shaped like a convex U to facilitate the placement of the stress isolation shield. In practical applications, after calibration is completed and the third flexible circuit board and calibration plate on the sensor circuit board are removed, a stress isolation shield can be installed for the accelerometer in the sensor circuit board before the sensor circuit board is placed into the sensor housing. Figure 4 The annular stress isolation shield 40 is shown in the image.

[0172] It should also be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0173] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention. Specific examples have been used in this application to illustrate the principles and implementation methods of the invention. The description of the above embodiments is only for the purpose of helping to understand the technical solution and core ideas of the invention. It should be noted that those skilled in the art can make several improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention.

Claims

1. A sensor circuit board for the Z-axis sensing direction, characterized in that, include: An accelerometer used to detect vibration and / or shock of the equipment under test, with the sensitive direction being the Z-axis; The base plate used to support the accelerometer; A first flexible circuit board connected to the base plate; A mounting plate equipped with a conditioning circuit has N layers, of which M layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the first flexible circuit board. The mounting plate is used to receive the sampling signal of the accelerometer through the base plate and the first flexible circuit board, process the sampling signal through the conditioning circuit, and output the processed detection signal. Here, M and N are both positive integers, representing the number of layers of the first flexible circuit board and the mounting plate, respectively, and M≤N. The base plate is provided with a groove so that when the installation is completed, the mounting plate is fixed to the base plate through the groove; It also includes: a calibration circuit connected to the accelerometer for calibrating the detection signal, the calibration circuit being disposed on the calibration fixture, or on the mounting plate, or on the calibration plate; When the calibration circuit is mounted on the calibration fixture, the sensor circuit board further includes a second flexible circuit board. The second flexible circuit board is connected to the base plate and has a calibration circuit interface. During calibration, the calibration fixture is connected to the second flexible circuit board through the calibration circuit interface. When the calibration circuit is installed on the calibration board, the calibration board is connected to the base plate through a third flexible circuit board. After the calibration test is completed, the connection between the third flexible circuit board and the base plate is cut off. The calibration board has a P layer, and the Q layer in the P layer is a flexible layer. The Q flexible layer is connected to the corresponding layer of the third flexible circuit board in a one-to-one correspondence. Here, P and Q are both positive integers, representing the number of layers of the third flexible circuit board and the calibration board, respectively, and Q≤P.

2. The sensor circuit board with Z-axis sensing direction according to claim 1, characterized in that, The accelerometer is fixed to the top of the base plate; The mounting plate is a mounting plate with a preset concave structure, so that after the mounting plate is fixed to the base plate through the groove, a receiving cavity is formed between the mounting plate and the base plate to accommodate the accelerometer.

3. The sensor circuit board with Z-axis sensing direction according to claim 2, characterized in that, Also includes: A temperature sensor, wherein the temperature sensor is fixed to the bottom of the base plate by a fixing component.

4. The sensor circuit board with Z-axis sensing direction according to claim 1, characterized in that, The groove provided on the base plate includes a first groove and a second groove; The mounting plate has a first connecting end and a second connecting end, wherein the first connecting end is inserted into the first groove and the second connecting end is inserted into the second groove; The first connecting end has an L-shaped structure in the thickness direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for engaging with the second groove. or; The first connecting end has an L-shaped structure in the length direction for engaging with the first groove, and the second connecting end has an L-shaped structure in the length direction for engaging with the second groove.

5. The sensor circuit board with Z-axis sensing direction according to claim 1, characterized in that, The conditioning circuit includes: The filtering circuit connected to the accelerometer is used to filter the sampled signal output by the accelerometer and expand the vibration frequency detection range; A signal conversion circuit connected to the filter circuit is used to amplify the output of the filter circuit, or to amplify the output of the filter circuit and convert voltage or current. An interface protection circuit for interference suppression is connected to the signal conversion circuit, and the output of the interface protection circuit serves as the output of the conditioning circuit, outputting the processed detection signal.

6. The sensor circuit board for the Z-axis sensing direction according to any one of claims 1 to 5, characterized in that, Also includes: A calibration circuit connected to the accelerometer for calibrating the detection signal, wherein the calibration circuit is an analog calibration circuit based on analog circuitry or a digital calibration circuit based on a controller.

7. The sensor circuit board with Z-axis sensing direction according to claim 6, characterized in that, The analog calibration circuit includes: a first voltage divider circuit and a second voltage divider circuit; The first voltage divider circuit is connected to the scaling factor compensation interface of the accelerometer and is used to adjust the excitation voltage amplitude applied to the differential capacitor of the accelerometer by controlling the voltage of the scaling factor compensation interface, so as to calibrate the sensitivity of the sensor on the sensor circuit board by adjusting the scaling factor of the accelerometer. The second voltage divider circuit is connected to the zero-bias compensation interface of the accelerometer and is used to calibrate the operating point of the sensor by adjusting the DC bias of the accelerometer by controlling the voltage of the zero-bias compensation interface.

8. The sensor circuit board with Z-axis sensing direction according to claim 7, characterized in that, The first voltage divider circuit includes a first voltage divider device and a second voltage divider device; The first terminal of the first voltage divider is connected to the first power supply terminal, the second terminal of the first voltage divider is connected to the first terminal of the second voltage divider and the scaling factor compensation interface, and the second terminal of the second voltage divider is grounded. The first voltage divider and / or the second voltage divider are voltage dividers with adjustable parameters to control the voltage of the scaling factor compensation interface; The second voltage divider circuit includes a third voltage divider device and a fourth voltage divider device. The first terminal of the third voltage divider device is connected to the second power supply terminal. The second terminal of the third voltage divider device is connected to the first terminal of the fourth voltage divider device and the zero bias compensation interface, respectively. The second terminal of the fourth voltage divider device is grounded. The third voltage divider and / or the fourth voltage divider are voltage dividers with adjustable parameters to control the voltage of the zero-bias compensation interface.

9. The sensor circuit board with Z-axis sensing direction according to claim 6, characterized in that, The digital calibration circuit includes a controller connected to the accelerometer, and is used for: The value of the first register in the accelerometer is controlled to control the amplification factor of the gain circuit in the accelerometer, so as to calibrate the sensitivity of the sensor on the sensor circuit board. The value of the second register in the accelerometer is controlled to control the value of the compensation capacitor connected in parallel to the upper or lower plate static capacitor of the differential capacitor of the accelerometer, so as to perform the operating point calibration of the sensor.

10. A sensor, characterized in that, The sensor circuit board includes the Z-axis sensing direction as described in any one of claims 1 to 9.

11. A calibration and installation method for a sensor circuit board, characterized in that, The sensor circuit board includes: an accelerometer for detecting vibration and / or impact of the device under test, with the sensitive direction being the Z-axis; a base plate for supporting the accelerometer; a first flexible circuit board connected to the base plate; a mounting plate provided with a conditioning circuit for receiving the sampling signal from the accelerometer through the base plate and the first flexible circuit board, processing the sampling signal through the conditioning circuit, and outputting the processed detection signal; and a calibration plate connected to the base plate through a third flexible circuit board, wherein the calibration plate is provided with a calibration circuit connected to the accelerometer for calibrating the detection signal. The calibration and installation method for the sensor circuit board includes: After the sensor circuit board is placed horizontally into the calibration fixture, the sensor circuit board is calibrated using the calibration fixture. The third flexible circuit board and the calibration plate on the sensor circuit board are removed; After fixing the mounting plate to the base plate through the groove provided on the base plate, the sensor circuit board is placed into the sensor housing; It also includes: a calibration circuit connected to the accelerometer for calibrating the detection signal, the calibration circuit being disposed on the calibration fixture, or on the mounting plate, or on the calibration plate; When the calibration circuit is mounted on the calibration fixture, the sensor circuit board further includes a second flexible circuit board. The second flexible circuit board is connected to the base plate and has a calibration circuit interface. During calibration, the calibration fixture is connected to the second flexible circuit board through the calibration circuit interface. When the calibration circuit is installed on the calibration board, the calibration board is connected to the base plate through a third flexible circuit board. After the calibration test is completed, the connection between the third flexible circuit board and the base plate is cut off. The calibration board has a P layer, and the Q layer in the P layer is a flexible layer. The Q flexible layer is connected to the corresponding layer of the third flexible circuit board in a one-to-one correspondence. Here, P and Q are both positive integers, representing the number of layers of the third flexible circuit board and the calibration board, respectively, and Q≤P.

12. The calibration and installation method for the sensor circuit board according to claim 11, characterized in that, The calibration fixture is a calibration fixture used for calibrating a batch of sensor circuit boards; After the sensor circuit board is placed horizontally into the calibration fixture, the sensor circuit board is calibrated using the calibration fixture, including: After the sensor circuit board is placed horizontally into the calibration fixture, batch calibration of multiple sensor circuit boards is performed using the calibration fixture.

13. The calibration and installation method for the sensor circuit board according to claim 11, characterized in that, Before fixing the mounting plate to the base plate via the groove provided on the base plate, the method further includes: A stress isolation cover is provided for the accelerometer in the sensor circuit board.

Images