Sensor, sensor circuit board in Z-axis sensitive direction and calibration and installation method of sensor circuit board

Abstract

The invention discloses a sensor, a sensor circuit board in a Z-axis sensitive direction and a calibration installation method of the sensor circuit board, and is applied to the technical field of detection. The bottom plate is used for bearing the accelerometer; the first flexible circuit board is connected with the bottom plate; the mounting plate is provided with a conditioning circuit, the mounting plate is provided with N layers, M layers in the N layers are flexible layers, and the M flexible layers are connected with the corresponding layers of the first flexible circuit board in a one-to-one correspondence manner; the mounting plate is used for receiving a sampling signal of the accelerometer through the bottom plate and the first flexible circuit board, processing the sampling signal through the conditioning circuit and outputting a detection signal obtained after processing; a groove is formed in the bottom plate, so that the mounting plate is fixed on the bottom plate through the groove after the mounting is completed. According to the scheme, Z-axis sensitive direction installation is supported, sensor working point calibration and sensitivity calibration are effectively achieved, and the small size of the sensor is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a sensor, a sensor circuit board in a Z-axis sensitive direction, and a calibration and installation method thereof. Background Art

[0002] When performing fault diagnosis, the accelerometer is a vibration and shock sensitive device. At present, MEMS (Micro ElectroMechanical System) accelerometers have been widely used due to their small size, high detection accuracy, shock resistance, and easy batch processing. According to the sensitive axis, the accelerometer can be divided into in-plane sensitive direction and out-of-plane sensitive direction. Figure 1 , is a schematic diagram of different sensitive directions of the accelerometer, where Figure 1 The left side is the in-plane sensitive direction, and the right side is the out-of-plane sensitive direction. Currently, most high-performance MEMS accelerometers use the Z-axis sensitive direction, that is, the out-of-plane sensitive direction. Such MEMS accelerometers usually need to be installed perpendicular to the vibration impact direction (different from the in-plane sensitive MEMS installation).

[0003] At present, MEMS accelerometers and peripheral circuits are generally soldered on a whole PCB (Printed Circuit Board), and then installed horizontally in the sensor housing. However, this type of PCB has a large area, which makes the sensor larger as a whole and cannot meet the requirement of small size of the sensor.

[0004] In summary, how to ensure the small size of the sensor while meeting the requirements of installation in the sensitive direction of the Z-axis is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

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

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

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

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

[0009] A base plate for carrying the accelerometer;

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

[0011] A mounting board provided with a conditioning circuit, the mounting board having N layers, M of the N layers being flexible layers, and the M flexible layers being connected one-to-one with corresponding layers of the first flexible circuit board; the mounting board is used to receive a sampling signal of the accelerometer through the bottom plate and the first flexible circuit board, process the sampling signal through the conditioning circuit, and output a detection signal obtained after the processing; wherein M and N are both positive integers, respectively representing the number of layers of the first flexible circuit board and the mounting board, and M≤N;

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

[0013] In one embodiment, it further comprises: a calibration circuit connected to the accelerometer and used to calibrate the detection signal, wherein the calibration circuit is arranged on a calibration fixture, or on the mounting board, or on the calibration board;

[0014] When the calibration circuit is arranged on the calibration jig, the sensor circuit board further comprises a second flexible circuit board, the second flexible circuit board is connected to the base plate, the second flexible circuit board is provided with a calibration circuit interface, and during calibration, the calibration jig is connected to the second flexible circuit board through the calibration circuit interface;

[0015] When the calibration circuit is arranged on the calibration board, the calibration board is connected to the base plate via a third flexible circuit board, and 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 P layers, and the Q layer in the P layers is a flexible layer, and the Q flexible layers are connected to the corresponding layers of the third flexible circuit board in a one-to-one correspondence, wherein 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, an accommodating cavity is formed between the mounting plate and the base plate to accommodate the accelerometer through the accommodating cavity.

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

[0020] In one embodiment, the groove provided on the bottom 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 cooperating with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for cooperating with the second groove;

[0023] or;

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

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

[0026] A filter circuit connected to the accelerometer, used for filtering the sampling signal output by the accelerometer and expanding the vibration frequency detection range;

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

[0028] An interface protection circuit is connected to the signal conversion circuit and is used for anti-interference, and the output of the interface protection circuit is used as the output of the conditioning circuit to output the detection signal obtained after processing.

[0029] In one embodiment, it further includes:

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

[0031] In one implementation, 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 scale factor compensation interface of the accelerometer, and is used to adjust the amplitude of the excitation voltage applied to the differential capacitor of the accelerometer by controlling the voltage of the scale factor compensation interface, so as to calibrate the sensitivity of the sensor where the sensor circuit board is located by adjusting the scale 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 controlling the voltage of the zero bias compensation interface and adjusting the DC bias of the accelerometer.

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

[0035] The first end of the first voltage divider is connected to the first power supply end, the second end of the first voltage divider is connected to the first end of the second voltage divider and the scale factor compensation interface respectively, and the second end of the second voltage divider is grounded;

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

[0037] The second voltage divider circuit comprises a third voltage divider device and a fourth voltage divider device, wherein a first end of the third voltage divider device is connected to the second power supply end, a second end of the third voltage divider device is respectively connected to a first end of the fourth voltage divider device and the zero-bias compensation interface, and a second end of the fourth voltage divider device is grounded;

[0038] The third voltage divider device and / or the fourth voltage divider device are voltage divider devices with adjustable parameters, so as 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 and configured to:

[0040] Controlling the value of a first register in the accelerometer, so as to control the amplification factor of a gain circuit in the accelerometer through the value of the first register, so as to calibrate the sensitivity of the sensor where the sensor circuit board is located;

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

[0042] In a second aspect, the present invention provides a sensor, including a sensor circuit board with a Z-axis sensitive direction as described above.

[0043] In a third aspect, the present invention provides a calibration and installation method for a sensor circuit board, wherein the sensor circuit board includes: an accelerometer for detecting vibration and / or impact of a device under test, with a sensitive direction being the Z axis; a base plate for carrying the accelerometer; a first flexible circuit board connected to the base plate; a mounting plate provided with a conditioning circuit, for receiving a sampling signal of the accelerometer through the base plate and the first flexible circuit board, processing the sampling signal through the conditioning circuit, and outputting a detection signal obtained after the processing; a calibration board connected to the base plate through a third flexible circuit board, and provided with a calibration circuit connected to the accelerometer for calibrating the detection signal;

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

[0045] After the sensor circuit board is horizontally placed in a calibration jig, the sensor circuit board is calibrated by the calibration jig;

[0046] Cutting off the third flexible circuit board and the calibration board on the sensor circuit board;

[0047] After the mounting plate is fixed to the bottom plate through the grooves provided on the bottom plate, the sensor circuit board is placed in the sensor housing.

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

[0049] After the sensor circuit board is horizontally placed in a calibration jig, the sensor circuit board is calibrated by the calibration jig, including:

[0050] After the sensor circuit board is horizontally placed in a calibration jig, batch calibration for multiple sensor circuit boards is performed by the calibration jig.

[0051] In one embodiment, before the mounting plate is fixed to the bottom plate through the groove provided on the bottom plate, the method further comprises:

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

[0053] By applying the technical solution provided in the embodiment of the present invention, through the design of soft boards, hard boards and soft-hard combined boards, and forming a three-dimensional board shape through the installation plate and the base plate, the Z-axis sensitive direction installation can be met and the small size of the sensor can be guaranteed.

[0054] Specifically, the accelerometer can detect the vibration and / or impact of the device under test, and a base plate for carrying the accelerometer is provided, that is, the accelerometer can be provided on the base plate, and the base plate can be installed perpendicular to the vibration impact direction, so that the sensor of the present application can be installed in the Z-axis sensitive direction. The first flexible circuit board is connected to the base plate, and the mounting plate is provided with a conditioning circuit, which can 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 detection signal obtained after the processing, and the vibration and / or impact of the device under test can be effectively reflected through the detection signal. Furthermore, the mounting board has N layers, and M of the N layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the first flexible circuit board. This design method eliminates the need to set a special joint when the first flexible circuit board is connected to the mounting board, which is beneficial to reducing the volume of the mounting board. Moreover, since a groove is provided on the bottom plate and the first flexible circuit board can be bent, the mounting board can be fixed to the bottom plate through the groove when the installation is completed, thereby forming a three-dimensional board shape. Compared with the traditional design of soldering the accelerometer and the peripheral circuit on a whole PCB, the three-dimensional board shape of the present application is beneficial to reducing the volume.

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

[0056] Furthermore, by providing a calibration circuit for calibrating the detection signal output by the conditioning circuit of the accelerometer, the sensitivity and working point of the sensor can be effectively calibrated. In addition, if the calibration circuit is provided on the calibration board, the third flexible circuit board can be cut off from the bottom board after the sensor calibration is completed in the manufacturing plant, so that a smaller sensor volume can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 Schematic diagram of different sensitive directions of the accelerometer;

[0059] Figure 2 A schematic diagram of the structure of a sensor circuit board in the Z-axis sensitive direction provided by a specific embodiment of the present invention;

[0060] Figure 3 It is a schematic diagram of a mounting plate being fixed to a bottom plate through a groove in a specific embodiment of the present invention;

[0061] Figure 4 An exploded view and a cross-sectional view of a sensor in a specific embodiment of the present invention;

[0062] Figure 5 A top view and a side view of a sensor circuit board in a Z-axis sensitive direction in a specific embodiment of the present invention;

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

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

[0065] Figure 8 A schematic diagram of a sensor structure in which a temperature sensor is provided in a specific embodiment of the present invention;

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

[0067] Fig.10 It is a structural schematic diagram of an analog calibration circuit in a specific implementation manner of the present invention;

[0068] Fig.11 A schematic diagram of the structure of a digital calibration circuit in a specific implementation manner of the present invention;

[0069] Fig.12 It is a structural schematic diagram of a conditioning circuit in a specific implementation manner of the present invention;

[0070] Fig.13 is a structural schematic diagram of a conditioning circuit in another specific implementation manner of the present invention;

[0071] Fig.14 It is a structural schematic diagram of a conditioning circuit in another specific implementation manner of the present invention;

[0072] Fig.15 A schematic diagram of accelerometer zero-position output noise in a specific implementation manner;

[0073] Fig.16 A schematic diagram showing comparison of vibration bandwidth extension test results in a specific implementation manner;

[0074] Fig.17 A schematic diagram of a sensor circuit board layout in a specific implementation manner;

[0075] Fig.18The figure is a flow chart of an implementation method of a calibration installation method of a sensor circuit board in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0076] The core of the present invention is to provide a sensor, a sensor circuit board in the Z-axis sensitive direction and a calibration and installation method thereof, and ensure the small size of the sensor, and effectively realize zero bias calibration and scale factor calibration.

[0077] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

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

[0079] An accelerometer 100 for detecting vibration and / or shock of the device under test, with the sensitive direction being the Z axis;

[0080] The bottom plate 201 is used to carry the accelerometer 100 ; the bottom plate 201 is provided with a groove, so that when the installation is completed, the mounting plate 203 is fixed on the bottom plate 201 through the groove.

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

[0082] A mounting board 203 with a conditioning circuit is provided, the mounting board 203 has N layers, and M of the N layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the first flexible circuit board 202; the mounting board 203 is used to receive the sampling signal of the accelerometer 100 through the bottom plate 201 and the first flexible circuit board 202, process the sampling signal through the conditioning circuit, and output the detection signal obtained after the processing, and the detection signal can effectively reflect the acceleration of the device under test, and can also effectively reflect the vibration and / or impact of the device under test. Wherein, M and N are both positive integers, representing the number of layers of the first flexible circuit board 202 and the mounting board 203, respectively, and M≤N.

[0083] In the solution of the present application, the specific type of the 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, and the sensitive direction is the Z axis.

[0084] The sampling signal output by the accelerometer 100 can reflect the acceleration of the device under test, thereby making it possible to analyze the vibration signal and impact signal of the device under test based on the acceleration of the device under test. Of course, in other specific occasions, 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] In order to effectively fix the accelerometer 100, a base plate 201 for carrying the accelerometer 100 is provided in the present application. The base plate 201 is usually a hard board, that is, it can be a commonly used hard PCB. The shape of the base plate 201 can be set as needed, for example Figure 2 In a specific embodiment, the accelerometer 100 is in a rectangular parallelepiped shape, and the bottom plate 201 is in a circular shape. In other embodiments, a suitable bottom plate shape can be selected according to needs, for example, according to the shape of the housing of the sensor.

[0086] The first flexible circuit board 202 is a soft board, i.e., a flexible circuit board, which is used for circuit routing, so that the sampling signal of the accelerometer 100 can be sent to the mounting board 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 board 203, and the mounting board 203 is provided with a conditioning circuit.

[0087] Figure 2 For ease of viewing, the mounting plate 203 is not inserted into the bottom plate 201. In actual applications, when the installation is completed, you can refer to Figure 3 , is a schematic diagram of a specific embodiment of the present invention in which the mounting plate 203 is fixed on the bottom plate 201 through a groove. Since the first flexible circuit board 202 is a soft board and can be bent, the mounting plate 203 can be fixed on the bottom plate 201 through the groove provided on the bottom plate 201, and a three-dimensional sensor structure is formed at this time. Compared with the design of welding the accelerometer 100 and the peripheral circuit on a whole PCB in the traditional solution, such a three-dimensional board form is conducive to reducing the volume.

[0088] Furthermore, the solution of the present application takes into account that the first flexible circuit board 202 is a soft board. If the mounting board 203 is set as a hard board, a special interface needs to be set at the contact part between the first flexible circuit board 202 and the mounting board 203, which is not conducive to reducing the volume and is also easily damaged due to bending. In this regard, in the solution of the present application, the mounting board 203 adopts a soft-hard combination board design, that is, the first flexible circuit board 202 is a soft board with M layers, and the mounting board 203 has N layers, M≤N, and M layers of the N layers are flexible layers, so that the M flexible layers in the mounting board 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 will use a soft board with flex resistance, high temperature resistance and high insulation, and the thickness is generally less than 0.2mm. It is usually set as one or two layers, and can usually be connected to the top or bottom of the mounting board 203. For example, in one case, M=2, that is, the first flexible circuit board 202 is a two-layer soft board, then the two layers of the first flexible circuit board 202 can be connected to the first layer and the second layer of the mounting board 203 respectively, the first layer and the second layer of the mounting board 203 are both flexible layers, and the first layer of the mounting board 203 is its top layer. For another example, the two layers of the first flexible circuit board 202 can be connected to the penultimate layer and the second to last layer of the mounting board 203 respectively. At this time, the penultimate layer and the second to last layer of the mounting board 203 are both flexible layers, and the penultimate layer of the mounting board 203 is its bottom layer. Of course, in addition to connecting to the top or bottom of the mounting board 203, in other embodiments, according to needs, the appropriate M layers among the N layers installed can be selected as flexible layers, and connected to the corresponding layers of the first flexible circuit board 202 one by one.

[0090] In summary, since the mounting board 203 adopts the above-mentioned hard-soft board design, the mounting board 203 can be directly connected to the first flexible circuit board 202 without setting a special interface, and the connection is not easily damaged by bending, thereby ensuring reliability.

[0091] In practical applications, the sensor usually needs to be provided with a sensor housing. Figure 2 and Figure 3 The housing is not shown in the figure. Figure 4 , Figure 4 1 is an exploded view and a cross-sectional view of a sensor in a specific embodiment. Figure 3 It can be seen that the inner cavity mounting surface of the sensor housing can effectively cooperate with the bottom plate 201 to achieve the fixation of the bottom plate 201 in the sensor housing. Figure 4 The housing includes an upper housing and a lower housing matched therewith. In other embodiments, other housing structures can 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 bottom plate 201, and the accelerometer 100 is arranged on the bottom plate 201, in order to effectively realize space utilization and reduce the volume of the sensor, after the mounting plate 203 is inserted into the groove of the bottom plate 201, the side of the mounting plate 203 close to the bottom plate 201 can usually be an arch bridge shape or other shapes that are easy to insert into the bottom plate 201 and do not affect the position of the accelerometer 100. In the above embodiments of the present application, it can be seen that Figure 2 and Figure 3 The mounting plates 203 are all in the shape of an arch bridge, that is, the square columns with steps on both sides thereof are inserted into the grooves of the bottom plate 201.

[0093] In addition, in practical applications, when the mounting plate 203 is inserted into the groove of the bottom plate 201, the side away from the bottom plate 201 can usually be set to 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 bottom plate 201, which is also conducive to avoiding stress interference to the accelerometer 100, and can also play a role in electrical isolation, improving the insulation between the mounting plate 203 and the sensor housing. Figure 4 An annular stress isolation cover 40 is shown in FIG.

[0094] See also Figure 5 , which are a top view and a side view of a sensor circuit board in a specific implementation manner, and it can be understood that at this time, the mounting plate 203 has not yet been inserted into the groove of the base plate 201, so the installation has not yet been completed. Figure 5 The mounting plate 203 is also provided with a long strip hole 50, which can also play a role of stress isolation and electrical isolation to a certain extent. The specific number and size of the long strip hole 50 can be set as needed. In addition, Figure 5 Also shown are three mounting holes forming a triangle on the base plate 201 for fixing the accelerometer 100 .

[0095] Although some traditional accelerometers have a high degree of integration, they are generally powered by 1.8V~5V, cannot be directly connected to the input interface of the industrial control or fault detection system, and do not support the calibration function. Some accelerometers are calibrated at the factory, but when downstream sensor application manufacturers purchase accelerometers for installation, the accelerometers are easily affected by factors such as surface mount installation angle and welding temperature stress, which introduces zero bias errors and changes the 0g zero position output. In addition, although sensor application manufacturers usually add hardware adjustment circuits to the post-stage circuits of the accelerometers, the adjustment circuits can be used to calibrate a single accelerometer within a certain range when the sensor is applied, but the calibration accuracy is usually not high, and the calibration efficiency is not high. Even the post-stage adjustment circuits will introduce certain errors, resulting in lower sensor sensitivity and more serious working point drift.

[0096] In a specific embodiment of the present invention, it can also include: a calibration circuit connected to the accelerometer 100 and used to calibrate the detection signal output by the conditioning circuit of the subsequent stage of the accelerometer 100, that is, to calibrate the sensor where the sensor circuit board is located through the calibration circuit.

[0097] The calibration circuit may be disposed on a calibration fixture, or on a mounting plate 203, or on a calibration plate 204;

[0098] When the calibration circuit is provided on the calibration jig, the calibration jig is connected to the base plate 201 via the second flexible circuit board during calibration, the second flexible circuit board is provided with a calibration circuit interface, and the calibration jig is connected to the second flexible circuit board via the calibration circuit interface during calibration;

[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 to separate the two components physically.

[0100] The calibration board 204 has P layers, and the Q layer in the P layer is a flexible layer, and the Q layer flexible layer is connected to the corresponding layer of the third flexible circuit board 205 in a one-to-one correspondence, wherein 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] In this embodiment, the sensor circuit board, that is, the output of the conditioning circuit, can be effectively calibrated through the calibration circuit, thereby improving the sensitivity of the sensor and calibrating the working point of the sensor. In addition, in order to ensure flexibility, this embodiment takes into account that the calibration circuit can be set on the calibration fixture, or on the mounting plate 203, or on the calibration plate 204 according to actual needs. When the calibration circuit is set on the calibration plate 204, since the third flexible circuit board 205 and the base plate 201 can be cut off and installed after the sensor calibration is completed in the manufacturing plant, a smaller sensor volume can be achieved.

[0102] See also Figure 6 , is a schematic diagram of the structure of a sensor circuit board in a Z-axis sensitive direction during calibration test in a specific implementation manner, Figure 6 In the embodiment of the present invention, the calibration circuit is arranged on the calibration board 204. The calibration board 204 in this embodiment adopts a hard-soft board, while the third flexible circuit board 205 is a soft board. The Q layer in the P layer of the calibration board 204 is a flexible layer, which is connected to the corresponding layer of the third flexible circuit board 205 in a one-to-one correspondence. This facilitates the connection between the calibration board 204 and the third flexible circuit board 205, and is also conducive to reducing the volume of the calibration board 204. Of course, since the calibration of the sensor circuit board only needs to be performed during the sensor assembly process or after the sensor circuit board is produced, when the calibration is completed, the calibration circuit is no longer needed when the sensor circuit board (or sensor) is used. Therefore, in order to save space and reduce the volume of the sensor, after the calibration test is completed, the physical connection between the third flexible circuit board 205 and the base plate 201 can be cut off, so that during installation, the calibration board 204 and the third flexible circuit board 205 do not need to be installed in the sensor housing, which means that only the calibration board 204 and the third flexible circuit board 205 need to be used during the calibration test, and after the calibration test is completed, they can be cut and removed by the board separation machine, which will not affect the volume of the sensor. In the above Figure 3 , Figure 4 as well as Figure 5 In the example of FIG. 2 , the calibration board 204 and the third flexible circuit board 205 are not shown, which may indicate an implementation mode in which the calibration circuit is disposed on the mounting plate 203, and thus the calibration board 204 and the third flexible circuit board 205 do not need to be disposed. It may also indicate that although the calibration board 204 and the third flexible circuit board 205 are disposed, the calibration test has been completed, and the calibration board 204 and the third flexible circuit board 205 have been removed, and therefore, in the state in which the installation is completed, the calibration board 204 and the third flexible circuit board 205 do not appear.

[0103] See also Figure 7 , is a schematic diagram of a sensor structure provided with a second flexible circuit board, Figure 7In the embodiment, the calibration circuit is arranged on the calibration jig, and the calibration jig is connected to the base plate 201 through the second flexible circuit board 206 during calibration, that is, the second flexible circuit board 206 needs to be connected to the base plate 201. In this embodiment, the calibration circuit is arranged on the calibration jig, and the second flexible circuit board 206 is provided with a calibration circuit interface, so as to realize the connection between the calibration circuit on the calibration jig and the sensor circuit board in the circuit. And it can be understood that after the calibration is completed, when the sensor circuit board is removed from the calibration jig, the connection between the calibration jig and the second flexible circuit board 206 will also be disconnected. Since the second flexible circuit board 206 is a soft board, after the calibration test is completed, a certain space can be reserved in the sensor housing during installation for placing the second flexible circuit board 206, so there is no need to remove the second flexible circuit board 206 after the calibration test. Of course, even if the second flexible circuit board 206 is a soft board and does not occupy a large space, there will still be a certain amount of space occupied. Therefore, in practical applications, in situations where the sensor size requirements are more stringent, the above-described implementation method of setting 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 cut and removed by a panel separation machine.

[0104] In some implementations, the calibration circuit can be directly disposed on the mounting board 203. The advantage is that no cutting operation is required, but the area of ​​the mounting board 203 will be increased to a certain extent. This can usually be used in situations where the sensor size requirements are not particularly high.

[0105] In one embodiment of the present invention, the accelerometer 100 is fixed on 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 bottom plate 201 through the groove, a receiving cavity is formed between the mounting plate 203 and the bottom plate 201 to receive the accelerometer 100 through the receiving cavity;

[0107] The sensor further includes a temperature sensor, and the temperature sensor is fixed to the bottom of the base plate 201 through a fixing component.

[0108] This implementation takes into account that in some cases, the sensor needs to detect temperature in addition to acceleration. Therefore, in this implementation, the accelerometer 100 can be fixed on 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 through a fixing component. Figure 8 , is a schematic diagram of a sensor structure in which a temperature sensor is provided in a specific implementation manner, Figure 8 and Figure 4The temperature sensor 80 is shown in the figure, and the temperature sensor 80 can be a temperature measuring component such as a platinum resistor, a thermocouple, a digital temperature sensor, etc. for detecting temperature. In addition, it should be noted that the temperature sensor 80 is fixed to the bottom of the base plate 201 by a fixing component, rather than directly fixing the temperature sensor 80 to the bottom of the base plate 201, because in actual applications, the preset position where the temperature needs to be measured and the preset position where the acceleration needs to be measured usually have a certain distance, and in addition, this can also avoid the interference of high temperature / low temperature on the accelerometer 100 to a certain extent. Figure 8 In the embodiment, the temperature sensor 80 is specifically fixed to the bottom of the base plate 201 by three cylindrical fixing components.

[0109] In addition, in this embodiment, the mounting plate 203 is a mounting plate 203 with a preset concave structure, such as the arch bridge shape described above. The concave structure is arranged on a designated side close to the bottom plate 201, and after the mounting plate 203 is fixed on the bottom plate 201 through the groove, due to the presence of the concave structure, a receiving cavity is formed between the mounting plate 203 and the bottom plate 201, which can accommodate the accelerometer 100, thereby effectively realizing space utilization and helping to reduce the volume of the sensor.

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

[0111] The mounting plate 203 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;

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

[0113] or;

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

[0115] This embodiment takes into account that in order to ensure stability, there can be multiple grooves set on the base plate 201. For example, this embodiment specifically includes a first groove and a second groove. Accordingly, the mounting plate 203 needs to have a corresponding first connecting end and a second connecting end, so as to be inserted into the first groove and the second groove respectively.

[0116] In addition, this embodiment takes into account that the mortise and tenon structure is conducive to ensuring the reliability of the connection, so an L-shaped structure can be used to achieve the mortise and tenon connection. Figure 5The side view in the figure shows that the first connection end is circled by an oval. Figure 5 In the embodiment, the first connection end has an L-shaped structure in the thickness direction for matching with the first groove, that is, the thickness of the portion of the first connection end inserted into the first groove is narrower, and the thickness of the portion not inserted into the first groove is wider, forming an L-shaped structure, that is, a step structure, which is conducive to ensuring the reliability of the connection. In addition, Figure 8 This implementation method is also adopted, and Figure 8 The figure shows the state after the mounting plate 203 is 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 cooperating with the first groove.

[0117] Still taking the first connection end as an example, please refer to Figure 7 ,For example Figure 7 The oval circle in the figure is the first connection end. Figure 7 In an embodiment, the first connecting end has an L-shaped structure in the length direction for cooperating with the first groove. After the L-shaped structure is inserted into the first groove, it is beneficial to ensure the reliability of the connection. Fig. 9 It adopts Figure 7 The implementation method is the state of installation completion, Fig. 9 The first connecting end is also circled in the figure. It can be seen that the first connecting end has an L-shaped structure in the length direction for cooperating with the first groove.

[0118] In the above implementation manner, the installation position of the calibration circuit is described, and there may be various specific circuit structures, as long as they can cooperate with the accelerometer 100 to realize calibration. For example, in a specific implementation manner 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 an analog circuit for calibration, or a digital calibration circuit based on a controller for calibration.

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

[0120] For example, in a 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, and 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 where the sensor circuit board is located 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 and is used to calibrate the zero bias of the accelerometer 100 by controlling the voltage of the zero bias compensation interface and adjusting the DC bias of the accelerometer 100 so as to calibrate the working point of the sensor.

[0123] The scale factor of the accelerometer 100, that is, the sensitivity of acceleration, is the ratio of the output of the acceleration sensitive axis to the input acceleration. Zero bias, also known as bias, is the DC output of the accelerometer when the acceleration is 0g, which determines the working point of the sensor. The unit is usually mg or the corresponding electrical output value. Zero bias affects the static working point of the sensor, that is, the output voltage value of the sensor in static state (usually V).

[0124] Since the accelerometer 100 itself may have accuracy problems, and the process of soldering to the circuit board will affect the sensitivity and zero bias of the accelerometer 100, and then affect the output of the conditioning circuit, and finally affect the sensitivity and working point of the sensor. Therefore, in order to improve the sensitivity and working point of the sensor, it is necessary to calibrate the output of the conditioning circuit, that is, to achieve the calibration of the sensitivity and working point of the sensor where the sensor circuit board is located.

[0125] This implementation takes into account that the excitation voltage amplitude of the differential capacitor of the accelerometer 100 will affect 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 of the accelerometer 100. 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, the first voltage divider circuit is connected to the scale factor compensation interface of the accelerometer 100, and then the voltage of the scale factor compensation interface is controlled, so that the scale factor of the accelerometer 100 can be adjusted. And it can be 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, and the sensitivity of the output of the conditioning circuit is calibrated, that is, the sensor is calibrated. When this implementation 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 scale 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 scale factor compensation interface.

[0126] And this implementation method takes into account that, in addition to the scale factor, the accelerometer 100 may also have zero bias due to reasons such as itself and the installation process, so this implementation method can also adjust the zero bias of the accelerometer 100, so as to calibrate the working point of the output of the conditioning circuit, and thus achieve the calibration of the working point of the sensor. Specifically, in this implementation method, the second voltage divider circuit is connected to the zero bias compensation interface of the accelerometer 100, and then the voltage of the zero bias compensation interface is controlled, so that the DC bias of the accelerometer 100 can be adjusted to achieve zero bias adjustment of the accelerometer 100, so as to calibrate the working point of the output of the conditioning circuit, that is, to calibrate the working point of the sensor. It can be understood that when adopting this implementation method, the accelerometer 100 needs to be pre-set 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 voltage divider circuit and the second voltage divider circuit can be set as needed, as long as they can achieve voltage control of the corresponding interface. Fig.10, is a schematic diagram of the structure of an analog calibration circuit in a specific implementation, wherein the first voltage divider circuit may include a first voltage divider device and a second voltage divider device. The first end of the first voltage divider device is connected to the first power supply terminal Vref1, the second end of the first voltage divider device is respectively connected to the first end of the second voltage divider device and the scale factor compensation interface, and the second end of the second voltage divider device is grounded;

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

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

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

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

[0132] Similarly, the second voltage divider circuit is composed of a third voltage divider device and a fourth voltage divider device, and has a simple structure. The third voltage divider device and / or the fourth voltage divider device need to be voltage dividers with adjustable parameters, so that the voltage of the zero-bias compensation interface can be controlled. Fig.10 In a specific implementation manner, the third voltage divider and the fourth voltage divider are respectively denoted as R12 and R13, and the zero bias compensation interface is denoted as Vbisa. One or both of the third voltage divider and the fourth voltage divider are resistors with adjustable resistance values, which can control the voltage of the zero bias compensation interface. In addition, in practical applications, when voltage division is performed based on the variable resistance diode D11, the accuracy is usually higher than that of an adjustable resistor.

[0133] In a specific embodiment of the present invention, please refer to Fig.11 The digital calibration circuit includes a controller 101, which is connected to the accelerometer 100 and is used to:

[0134] Controlling the value of the first register in the accelerometer 100, so as to control the amplification factor of the gain circuit in the accelerometer 100 through the value of the first register, so as to calibrate the sensitivity of the sensor where the sensor circuit board is located;

[0135] The value of the second register in the accelerometer 100 is controlled to control the compensation capacitance value of the upper plate static capacitance or the lower plate static capacitance connected in parallel to the differential capacitance of the accelerometer 100 through the value of the second register, so as to calibrate the working point of the sensor.

[0136] In this implementation, a controller 101 is used for digital calibration, and the controller 101 can generally be an MCU. Specifically, considering that there are multiple gain circuits in the accelerometer 100, the amplification factors of these gain circuits are controlled by the value of the first register, so that the output voltage of the circuit can be amplified or reduced to adjust the scale factor. Therefore, in this implementation, the controller 101 controls the value of the first register. The scale factor of the accelerometer 100 is adjusted to achieve sensitivity calibration of the sensor where the sensor circuit board is located. In practical applications, the gain circuit is set at 1 Byte, and the adjustable range is 1 to 256 times.

[0137] A plurality of groups of differential capacitors are arranged in the accelerometer 100, and these capacitors can be respectively connected in parallel to the upper plate static capacitor or the lower plate static capacitor of the accelerometer 100 header. The value of the second register can be used to control 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. The zero bias of the accelerometer 100 can be adjusted by adjusting the static capacitor, thereby realizing the operating point calibration of the sensor.

[0138] It should also be noted that when the accelerometer 100 is calibrated by the controller 101, the scale factor compensation interface and the zero bias compensation interface can also be voltage-controlled to achieve calibration of the sensor where the sensor circuit board is located, for example Fig.11In the embodiment, the controller 101 is not only connected to the accelerometer 100 through the SPI interface (MCLK and MOSI), but also connected to the scale factor compensation interface (Vsens) and the zero bias compensation interface (Vbias) through the DAC0 and DAC1 interfaces. When this method is used in actual applications, the coarse adjustment of the calibration is usually achieved through the voltage control of the scale factor compensation interface and the zero bias compensation interface, and the fine adjustment of the calibration is achieved by controlling the values ​​of the first register and the second register. In other embodiments, one of the scale factor compensation interface (Vsens) and the zero bias compensation interface (Vbias) can be controlled by the controller 101, and the other can be set to a fixed voltage value, or the voltage can be controlled by an analog calibration circuit, that is, if necessary, a combination of an analog calibration circuit and a digital calibration circuit can be used to achieve calibration, and the present application does not limit this. For example, as follows Fig.14 In the implementation mode, the voltage of the zero bias compensation interface (Vbias) is controlled by the third voltage divider device R12 and the fourth voltage divider device R13, the voltage of the scale factor compensation interface (Vsens) is fixed, and the controller 101 is used to calibrate the accelerometer 100. Fig.14 The controller 101 is not shown.

[0139] As described above, the calibration circuit can be arranged on the second flexible circuit board 206, or on the mounting board 203, or on the calibration board 204. It can be understood that if an analog calibration circuit design is adopted, the calibration circuit can be selected to be arranged on the second flexible circuit board 206 or on the mounting board 203. If a digital calibration circuit design is adopted, and the digital calibration circuit is selected to be arranged on the second flexible circuit board 206 or on the mounting board 203, after the calibration is completed, the relevant calibration parameters can be stored in the digital calibration circuit, for example, specifically stored in the flash of the MCU. If the digital calibration circuit is arranged on the calibration board 204, since the calibration board 204 will be cut off after the calibration is completed, the relevant calibration parameters obtained by the calibration need to be stored in the accelerometer 100, for example, in the OTP (a non-volatile storage area) of the accelerometer 100, and when this solution is adopted, the voltages of the scale factor compensation interface and the zero bias compensation interface of the accelerometer 100 are usually set to fixed values, for example Fig.13 In the implementation method, such a design is adopted, the voltage of the scale factor compensation interface and the zero bias compensation interface of the accelerometer 100 is fixed, and the controller can be set on the calibration board 204. After the calibration is completed, the calibration board 204 will be cut off, which effectively reduces the volume of the sensor and improves reliability. In addition, Fig.12 The controller 101 is not shown in FIG.

[0140] The sampling signal sent by the accelerometer 100 needs to be transmitted to the conditioning circuit of the mounting board 203, and processed by the conditioning circuit. The signal after processing is used as the detection signal obtained by the sensor. The specific circuit structure of the conditioning circuit can be set according to actual needs. For example, the conditioning circuit can usually perform operations such as voltage amplification and current-voltage conversion.

[0141] In a specific embodiment of the present invention, please refer to Fig.12 , is a schematic diagram of a structure of a conditioning circuit in a specific implementation manner, and the conditioning circuit may include:

[0142] A filter circuit 301 connected to the accelerometer 100, for filtering the sampled signal output by the accelerometer 100 and expanding the vibration frequency detection range;

[0143] The signal conversion circuit 302 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 convert it into voltage or current;

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

[0145] This implementation takes into account that the accelerometer 100 has a resonance peak output, and the use bandwidth of the traditional accelerometer 100 is 1 / 3 of the resonance frequency. In order to balance sensitivity and noise, the natural frequency design of some accelerometers 100 will be less than 30kHz, which cannot meet the demand for a use bandwidth of more than 10kHz. In this implementation, a filter circuit 301 is connected to the output end of the accelerometer 100 for filtering, which is usually a first-order RC low-pass filter circuit, which can not only filter out high-frequency noise, but also suppress the resonance peak, thereby expanding the use bandwidth of the accelerometer 100, that is, effectively expanding the vibration frequency detection range.

[0146] Fig.12 The calibration circuit 304 and the power supply circuit 305 connected to the accelerometer 100 are also shown. The power supply circuit 305 is connected to the calibration circuit 304, the signal conversion circuit 302 and the accelerometer 100 respectively, so as to provide power to the calibration circuit 304, the signal conversion circuit 302 and the components / circuits in the accelerometer 100 that need power supply, and the voltage levels required by different components / circuits may be different. In addition, since the filter circuit 301 adopts a passive filter circuit, Fig.12 The power supply circuit 305 is not connected to the filter circuit 301 . In other implementations, an active filter circuit may be used according to actual needs and the power supply circuit 305 may be used to provide the required electrical energy.

[0147] See also Fig.13 , is a schematic diagram of the structure of a conditioning circuit in another specific implementation. Fig.13 In the implementation manner, the output end of the accelerometer 100 is Vmems, and the filter circuit 301 specifically adopts a first-order RC low-pass filter circuit, and the resistor and capacitor in the first-order RC low-pass filter circuit are respectively recorded as R0 and C0. In addition, in some implementation manners, 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. It can also 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 type sensor or a voltage output type sensor, and the design can be made according to actual needs, for example Fig.13 In the example, the signal conversion circuit 302 is composed of an operational amplifier and two resistors, which can amplify the output of the filter circuit 301 and is a voltage output type sensor. Fig.14 In the example, the signal conversion circuit 302 is composed of an operational amplifier, a resistor and a switch tube, which can convert the voltage signal into a current signal and amplify the output of the filter circuit 301.

[0149] The interface protection circuit 303 has various structures, for example, Fig.13 The output of the interface protection circuit 303 is realized by using a transient voltage suppression diode RV1 in the embodiment of the present invention, which has a simple structure and low cost. Fig.13 In addition, Fig.13 and Fig.14 In both figures, a power supply circuit is shown above the signal conversion circuit 302, which can realize circuit power supply. In other specific implementations, the specific structure of the power supply circuit can be set as needed.

[0150] By applying the technical solution provided in the embodiment of the present invention, through the design of a soft board and a soft-hard combination board, and forming a three-dimensional board shape through a mounting plate and a base plate, the Z-axis sensitive direction installation can be met, and the small size of the sensor can be guaranteed.

[0151] Specifically, the accelerometer can detect the vibration and / or impact of the device under test, and a base plate for carrying the accelerometer is provided, that is, the accelerometer can be provided on the base plate, and the base plate can be installed perpendicular to the vibration impact direction, so that the sensor of the present application can be installed in the Z-axis sensitive direction. The first flexible circuit board is connected to the base plate, and the mounting plate is provided with a conditioning circuit, which can 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 detection signal obtained after the processing, and the vibration and / or impact of the device under test can be effectively reflected through the detection signal. Furthermore, the mounting board has N layers, and M of the N layers are flexible layers, and the M flexible layers are connected one-to-one with the corresponding layers of the first flexible circuit board. This design method eliminates the need to set a special joint when the first flexible circuit board is connected to the mounting board, which is beneficial to reducing the volume of the mounting board. Moreover, since a groove is provided on the bottom plate and the first flexible circuit board can be bent, the mounting board can be fixed to the bottom plate through the groove when the installation is completed, thereby forming a three-dimensional board shape. Compared with the traditional design of soldering the accelerometer and the peripheral circuit on a whole PCB, the three-dimensional board shape of the present application is beneficial to reducing the volume.

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

[0153] In a specific implementation of the actual application, the overall circuit board size of the present application can meet the requirements of a diameter of less than or equal to 12.5 mm and a height of less than 16 mm, which can meet the installation requirements of miniaturized sensors (sensor diameter is less than or equal to 18.5 mm). After the sensor is installed, the vibration and impact response are good, the vibration sensitivity distribution range reaches 99.05%~102.22% of 20mV / g, and the impact SV value detection range is 0~10000SV.

[0154] by Fig.13 For example, in one implementation, the host computer can control the controller 101 through a serial port or a digital bus, and the controller 101 can set the register value in the accelerometer 100, set the PGA gain switch through the value of the first register, control the amplification factor of the gain circuit in the accelerometer 100, and adjust the scale factor, for example, the adjustment step is 0.025mV / g, and the adjustment range is 10mV / g±10mV / g. Through the value of the second register, the static differential capacitance value is compensated, thereby adjusting the zero output of the accelerometer 100, for example, the adjustment step is 25mV, and the adjustment range is 2.5V±1.5V.

[0155] For example, in one case, the output operating point of the sensor is required to be 5V and the sensitivity is 20mV / g. The register parameters of the accelerometer 100 can be set by the controller 101 to calibrate the zero bias to 2.5V±0.025V and the scale factor to 10mV / g±0.025mV / g. Fig.13 The signal conversion circuit in the conditioning circuit is specifically set to a 2x amplification common-mode amplifier, so 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 Fig.15 , is a schematic diagram of accelerometer zero-position output noise in a specific implementation mode, Fig.15 In the embodiment, the zero-position output noise of the accelerometer 100 is about 0.4mVpp, and the 0g zero-position output is stable for a long time; by configuring the registers of the digital calibration circuit, the accurate output of the sensor operating point 5.0196V (+1g) and the sensitivity 20mV / g is achieved.

[0157] See also Fig.16 When the conventional accelerometer has a resonant peak output and the vibration bandwidth cannot reach 10kHz, the filter circuit 301 in the conditioning circuit is adjusted in the embodiment of the present application to adjust the 10kHz amplitude-frequency response error of the accelerometer 100 from +4.25dB to 0.13dB. Fig.16 This is a schematic diagram for comparing the vibration bandwidth expansion test results. The upper figure is the amplitude-frequency response before setting the first-order RC filter circuit, and the lower figure is 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 in the Z-axis sensitive direction, an embodiment of the present invention further provides a sensor, which may include a sensor circuit board in the Z-axis sensitive direction as in any of the above embodiments, which may correspond to the above.

[0159] An embodiment of the present invention also provides a calibration and installation method for a sensor circuit board, wherein the sensor circuit board includes: an accelerometer for detecting vibration and / or impact of a device under test, with a sensitive direction being the Z axis; a base plate for carrying the accelerometer; a first flexible circuit board connected to the base plate; a mounting plate provided with a conditioning circuit, which is used to receive a 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 a detection signal obtained after the processing; and a calibration board connected to the base plate through a third flexible circuit board, and the calibration board is provided with a calibration circuit connected to the accelerometer for calibrating the detection signal.

[0160] See also Fig.18 The calibration installation method of the sensor circuit board may include the following steps:

[0161] Step S101: after placing the sensor circuit board horizontally in a calibration jig, calibrate the sensor circuit board using the calibration jig;

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

[0163] Step S103: After the mounting plate is fixed on the bottom plate through the grooves provided on the bottom plate, the sensor circuit board is placed in 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 in a calibration jig, and then the sensor circuit board can be calibrated through the calibration jig. The calibration circuit provided in the sensor circuit board can be the analog calibration circuit or the digital calibration circuit described above. The calibration principle can be found in the above description and will not be repeated here.

[0165] In this embodiment, the calibration circuit is arranged on the calibration board, and the calibration board is connected to the bottom plate through the third flexible circuit board. After the calibration is completed, the third flexible circuit board and the calibration board on the sensor circuit board can be cut off, that is, the connection between the third flexible circuit board and the bottom plate is cut off, thereby cutting off the third flexible circuit board and the calibration board, so that the sensor circuit after the calibration is completed has a small volume, which also ensures the small volume of the sensor.

[0166] In addition, it should be noted that, for the solution using the second flexible printed circuit board, calibration can also be performed using a calibration fixture.

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

[0168] After the sensor circuit board is placed horizontally in the calibration jig, batch calibration for multiple sensor circuit boards is performed through the calibration jig.

[0169] In this implementation, in order to improve the calibration efficiency, multiple sensor circuit boards can be placed horizontally in the calibration fixture, and calibration can be performed in batches at one time through the calibration interface, which is conducive to improving the calibration efficiency and pass rate. For example, the motion control of the calibration fixture is required during the calibration process, at this time, the corresponding sensor circuit boards can be calibrated one by one. Fig.17, is a schematic diagram of the plate-like morphology of the sensor circuit board in a specific implementation method, the left side is a scheme with a calibration board, and the right side is a scheme with a second flexible circuit board. As described above, when calibrating in the solution of the present application, the accelerometer is not calibrated separately after the accelerometer is produced, but the accelerometer, base plate, mounting plate and other boards are connected, that is, the sensor circuit board has been generated and connected, and then placed horizontally in the calibration jig for calibration, that is, the entire sensor circuit board is calibrated together, which improves the calibration accuracy. The calibration process can be a single sensor circuit board calibrated separately, or a calibration jig can be used to calibrate multiple circuit boards at the same time. In this implementation method, it is a schematic diagram of the plate-like morphology of the sensor circuit board to meet the batch calibration of multiple sensor circuit boards at the same time through the calibration jig.

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

[0171] As described above, when the mounting plate 203 is inserted into the groove of the bottom plate 201, the side away from the bottom plate 201 can usually be set to a convex shape to facilitate the placement of the stress isolation cover. In practical applications, after the calibration is completed and the third flexible circuit board and the calibration board on the sensor circuit board are cut off, the stress isolation cover can be set for the accelerometer in the sensor circuit board, and then the sensor circuit board can be placed in the sensor housing. Figure 4 An annular stress isolation cover 40 is shown in FIG.

[0172] It should also be noted that, in this application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0173] Those skilled in the art may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention. Specific examples are used in this application to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A sensor circuit board with a Z-axis sensitive direction, characterized in that: include: An accelerometer used to detect vibration and / or shock of the device under test, with the sensitive direction being the Z axis; A base plate for carrying the accelerometer; A first flexible circuit board connected to the base plate; A mounting board provided with a conditioning circuit, the mounting board having N layers, M of the N layers being flexible layers, and the M flexible layers being connected one-to-one with corresponding layers of the first flexible circuit board; the mounting board is used to receive a sampling signal of the accelerometer through the bottom plate and the first flexible circuit board, process the sampling signal through the conditioning circuit, and output a detection signal obtained after the processing; wherein M and N are both positive integers, respectively representing the number of layers of the first flexible circuit board and the mounting board, and M≤N; The bottom plate is provided with a groove, so that when the installation is completed, the mounting plate is fixed on the bottom plate through the groove.

2. The sensor circuit board of the Z-axis sensitive direction according to claim 1, characterized in that: Also includes: A calibration circuit connected to the accelerometer and used for calibrating the detection signal, wherein the calibration circuit is arranged on a calibration fixture, or on the mounting board, or on the calibration board; When the calibration circuit is arranged on the calibration jig, the sensor circuit board further comprises a second flexible circuit board, the second flexible circuit board is connected to the base plate, the second flexible circuit board is provided with a calibration circuit interface, and during calibration, the calibration jig is connected to the second flexible circuit board through the calibration circuit interface; When the calibration circuit is arranged on the calibration board, the calibration board is connected to the base plate via a third flexible circuit board, and 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 P layers, and the Q layer in the P layers is a flexible layer, and the Q flexible layers are connected to the corresponding layers of the third flexible circuit board in a one-to-one correspondence, wherein 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.

3. The sensor circuit board of the Z-axis sensitive direction according to claim 1, characterized in that: The accelerometer is fixed on 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, an accommodating cavity is formed between the mounting plate and the base plate to accommodate the accelerometer through the accommodating cavity.

4. The sensor circuit board of the Z-axis sensitive direction according to claim 3, characterized in that: Also includes: A temperature sensor is provided, and the temperature sensor is fixed to the bottom of the base plate through a fixing component.

5. The sensor circuit board of the Z-axis sensitive direction according to claim 1, characterized in that: The grooves arranged on the bottom plate include 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 cooperating with the first groove, and the second connecting end has an L-shaped structure in the thickness direction for cooperating with the second groove; or; The first connecting end has an L-shaped structure in the length direction for cooperating with the first groove, and the second connecting end has an L-shaped structure in the length direction for cooperating with the second groove.

6. The sensor circuit board of the Z-axis sensitive direction according to claim 1, characterized in that: The conditioning circuit comprises: A filter circuit connected to the accelerometer, used for filtering the sampling signal output by the accelerometer and expanding the vibration frequency detection range; A signal conversion circuit connected to the filter circuit, used to amplify the output of the filter circuit, or to amplify the output of the filter circuit and convert it into voltage or current; An interface protection circuit is connected to the signal conversion circuit and is used for anti-interference, and the output of the interface protection circuit is used as the output of the conditioning circuit to output the detection signal obtained after processing.

7. The sensor circuit board of any one of claims 1 to 6, characterized in that: Also includes: A calibration circuit connected to the accelerometer and used for calibrating the detection signal, wherein the calibration circuit is an analog calibration circuit that performs calibration based on an analog circuit, or a digital calibration circuit that performs calibration based on a controller.

8. The sensor circuit board of the Z-axis sensitive direction according to claim 7, characterized in that: The analog calibration circuit comprises: a first voltage divider circuit and a second voltage divider circuit; The first voltage divider circuit is connected to the scale factor compensation interface of the accelerometer, and is used to adjust the amplitude of the excitation voltage applied to the differential capacitor of the accelerometer by controlling the voltage of the scale factor compensation interface, so as to calibrate the sensitivity of the sensor where the sensor circuit board is located by adjusting the scale 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 controlling the voltage of the zero bias compensation interface and adjusting the DC bias of the accelerometer.

9. The sensor circuit board of the Z-axis sensitive direction according to claim 8, characterized in that: The first voltage dividing circuit includes a first voltage dividing device and a second voltage dividing device; The first end of the first voltage divider is connected to the first power supply end, the second end of the first voltage divider is connected to the first end of the second voltage divider and the scale factor compensation interface respectively, and the second end of the second voltage divider is grounded; The first voltage divider device and / or the second voltage divider device are voltage dividers with adjustable parameters, so as to control the voltage of the scale factor compensation interface; The second voltage divider circuit comprises a third voltage divider device and a fourth voltage divider device, wherein a first end of the third voltage divider device is connected to the second power supply end, a second end of the third voltage divider device is respectively connected to a first end of the fourth voltage divider device and the zero-bias compensation interface, and a second end of the fourth voltage divider device is grounded; The third voltage divider device and / or the fourth voltage divider device are voltage divider devices with adjustable parameters, so as to control the voltage of the zero-bias compensation interface.

10. The sensor circuit board of the Z-axis sensitive direction according to claim 7, characterized in that: The digital calibration circuit includes a controller connected to the accelerometer and configured to: Controlling the value of a first register in the accelerometer, so as to control the amplification factor of a gain circuit in the accelerometer through the value of the first register, so as to calibrate the sensitivity of the sensor where the sensor circuit board is located; The value of the second register in the accelerometer is controlled to control the compensation capacitance value of the upper plate static capacitance or the lower plate static capacitance connected in parallel to the differential capacitance of the accelerometer through the value of the second register, so as to calibrate the operating point of the sensor.

11. A sensor, characterized in that: A sensor circuit board comprising the Z-axis sensitive direction as claimed in any one of claims 1 to 10.

12. 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 carrying the accelerometer; a first flexible circuit board connected to the base plate; a mounting board provided with a conditioning circuit, for receiving a sampling signal of the accelerometer through the base plate and the first flexible circuit board, processing the sampling signal through the conditioning circuit, and outputting a detection signal obtained after the processing; a calibration board connected to the base plate through a third flexible circuit board, and provided with a calibration circuit connected to the accelerometer for calibrating the detection signal; The calibration and installation method of the sensor circuit board includes: After the sensor circuit board is horizontally placed in a calibration jig, the sensor circuit board is calibrated by the calibration jig; Cutting off the third flexible circuit board and the calibration board on the sensor circuit board; After the mounting plate is fixed to the bottom plate through the grooves provided on the bottom plate, the sensor circuit board is placed in the sensor housing.

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

14. The calibration and installation method of a sensor circuit board according to claim 12, characterized in that: Before the mounting plate is fixed on the bottom plate through the grooves provided on the bottom plate, the method further comprises: A stress isolation cover is provided for the accelerometer in the sensor circuit board.

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