Sensor and sensor circuit board

Abstract

The utility model discloses a sensor and a sensor circuit board, which are applied to the technical field of detection, and comprise an accelerometer for detecting vibration and / or impact of detected equipment; 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 N layers, M 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 conditioning circuit is used for receiving and processing a sampling signal of the accelerometer and outputting a detection signal; a groove is formed in the bottom plate, and the mounting plate is fixed to the bottom plate through the groove after mounting is completed. The side, away from the bottom plate, of the mounting plate is provided with a convex part for placing the stress isolation cover after mounting is completed. According to the scheme, Z-axis sensitive direction installation is supported, sensor working point calibration and sensitivity calibration are effectively achieved, stress interference caused to an accelerometer can be avoided, the insulativity between the installation plate and the sensor shell is improved, and the small size of the sensor is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to detection technical field, in particular to a kind of sensor and sensor circuit board. BACKGROUND

[0002] When carrying out fault diagnosis, accelerometer is vibration impact sensitive device. At present, MEMS (Micro ElectroMechanical System, microelectromechanical system) accelerometer is widely applied due to the characteristics of smaller volume, high detection precision, impact resistance and easy batch processing. According to the division of sensitive axis, acceleration plan can be divided into in-plane sensitive direction and out-of-plane sensitive direction, please refer to Figure 1 , the schematic diagram of different sensitive directions of accelerometer, wherein Figure 1 The left side of the in-plane sensitive direction, the right side is out-of-plane sensitive direction. The Z-axis sensitive direction, i.e. out-of-plane sensitive direction, is adopted in more excellent MEMS accelerometer at present, and such MEMS accelerometer usually needs to be installed perpendicular to vibration impact direction (different from in-plane sensitive MEMS installation).

[0003] At present, MEMS accelerometer and peripheral circuit are generally welded on a whole PCB (Printed Circuit Board, printed circuit board), and then installed horizontally in sensor shell, but such PCB is large in area, so that sensor is large as a whole, and the requirement of small size of sensor cannot be met.

[0004] In summary, how to meet the installation of Z-axis sensitive direction while guaranteeing the small size of sensor is a technical problem that the technical personnel in the field urgently need to solve at present. CONTENT OF UTILITY MODEL

[0005] The utility model aims at providing a kind of sensor and sensor circuit board, to meet the installation of Z-axis sensitive direction while guaranteeing the small size of sensor.

[0006] To solve the above technical problem, the utility model provides the following technical scheme:

[0007] First, the utility model provides a kind of sensor circuit board, comprising:

[0008] accelerometer for detecting the vibration and / or impact of measured equipment;

[0009] bottom plate for bearing the accelerometer;

[0010] first flexible circuit board connected with the bottom plate;

[0011] The mounting plate has N layers, and M layers of the N layers are flexible layers, and the M flexible layers are connected one by one with corresponding layers of the first flexible circuit board; wherein, M and N are positive integers, respectively representing the number of layers of the first flexible circuit board and the mounting plate, and M≤N;

[0012] A conditioning circuit is arranged on the bottom plate and / or the mounting plate, and the conditioning circuit is used to receive a sampling signal of the accelerometer and process the sampling signal, and output a detection signal obtained after processing;

[0013] The bottom plate is provided with a groove, so that when the mounting is completed, the mounting plate is fixed on the bottom plate through the groove;

[0014] The mounting plate is provided with a convex part on the side away from the bottom plate when the mounting is completed, so as to place a stress isolation cover through the convex part.

[0015] In an embodiment, the accelerometer is an accelerometer with a sensitive direction of Z axis.

[0016] In an embodiment, the mounting plate is provided with a stress isolation hole on the side away from the bottom plate when the mounting is completed.

[0017] In an embodiment, further comprising: a calibration circuit connected with the accelerometer, used to calibrate the detection signal, the calibration circuit is arranged on a calibration fixture, or arranged on the mounting plate, or arranged on the calibration plate;

[0018] When the calibration circuit is arranged on the calibration fixture, the sensor circuit board further comprises a second flexible circuit board, the second flexible circuit board is connected with the bottom plate, and the second flexible circuit board is provided with a calibration circuit interface, and the calibration fixture is connected with the second flexible circuit board through the calibration circuit interface during calibration;

[0019] When the calibration circuit is arranged on the calibration plate, the calibration plate is connected with the bottom plate through a third flexible circuit board, and the connection between the third flexible circuit board and the bottom plate is cut off after completing the calibration test;

[0020] The calibration plate has P layers, and Q layers of the P layers are flexible layers, and the Q flexible layers are connected one by one with corresponding layers of the third flexible circuit board, wherein, P and Q are positive integers, respectively representing the number of layers of the third flexible circuit board and the calibration plate, and Q≤P.

[0021] In an embodiment, the accelerometer is fixed on the top of the bottom plate;

[0022] The mounting plate is a mounting plate with a preset concave structure, so that after the mounting plate is fixed on the bottom plate through the groove, a containing cavity is formed between the mounting plate and the bottom plate to contain the accelerometer through the containing cavity.

[0023] In an embodiment, further comprising a temperature sensor fixed on the bottom of the bottom plate by a fixing component.

[0024] In an embodiment, the groove provided on the bottom plate comprises a first groove and a second groove.

[0025] The mounting plate has a first connecting end and a second connecting end, and the first connecting end is inserted into the first groove, and the second connecting end is inserted into the second groove.

[0026] 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.

[0027] Or;

[0028] 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.

[0029] In an embodiment, the conditioning circuit comprises:

[0030] A filter circuit connected with the accelerometer, for filtering the sampling signal output by the accelerometer and expanding the vibration frequency detection range;

[0031] A signal conversion circuit connected with the filter circuit, for amplifying the output of the filter circuit, or amplifying the output of the filter circuit and voltage or current conversion;

[0032] An interface protection circuit connected with the signal conversion circuit for anti-interference, and the output of the interface protection circuit is used as the output of the conditioning circuit, and the detection signal obtained after output processing.

[0033] In an embodiment, further comprising:

[0034] A calibration circuit connected with the accelerometer for calibrating the detection signal, the calibration circuit being an analog calibration circuit based on an analog circuit for calibration, or a digital calibration circuit based on a controller for calibration.

[0035] In an embodiment, the analog calibration circuit comprises a first voltage dividing circuit and a second voltage dividing circuit;

[0036] The first voltage dividing circuit is connected with a scale factor compensation interface of the accelerometer, and is used for adjusting an excitation voltage amplitude of a differential capacitance of the accelerometer by controlling a voltage of the scale factor compensation interface, so as to calibrate a sensitivity of a sensor where the sensor circuit board is located by adjusting a scale factor of the accelerometer.

[0037] The second voltage dividing circuit is connected with a zero offset compensation interface of the accelerometer, and is used for adjusting a direct current bias of the accelerometer by controlling a voltage of the zero offset compensation interface, so as to calibrate a working point of the sensor.

[0038] In an embodiment, the first voltage dividing circuit comprises a first voltage dividing device and a second voltage dividing device.

[0039] A first end of the first voltage dividing device is connected with a first power supply end, a second end of the first voltage dividing device is connected with a first end of the second voltage dividing device and the scale factor compensation interface respectively, and a second end of the second voltage dividing device is grounded.

[0040] The first voltage dividing device and / or the second voltage dividing device is a voltage dividing device with adjustable parameters, so as to control the voltage of the scale factor compensation interface.

[0041] The second voltage dividing circuit comprises a third voltage dividing device and a fourth voltage dividing device, a first end of the third voltage dividing device is connected with a second power supply end, a second end of the third voltage dividing device is connected with a first end of the fourth voltage dividing device and the zero offset compensation interface respectively, and a second end of the fourth voltage dividing device is grounded.

[0042] The third voltage dividing device and / or the fourth voltage dividing device is a voltage dividing device with adjustable parameters, so as to control the voltage of the zero offset compensation interface.

[0043] In an embodiment, the digital calibration circuit comprises a controller connected with the accelerometer, and is used for calibrating the sensitivity of the sensor where the sensor circuit board is located by controlling a value of a first register in the accelerometer, and calibrating the working point of the sensor by controlling a value of a second register in the accelerometer.

[0044] In a second aspect, the utility model provides a kind of sensor, including the sensor circuit board as described above.

[0045] The technical scheme provided by the embodiments of the utility model is applied, through the design of soft board and soft and hard combination board, and through the installation plate and the bottom plate form the three-dimensional board card form, the Z-axis sensitive direction installation can be met, and the small size of the sensor is guaranteed.

[0046] Specifically, the accelerometer can detect the vibration and / or impact of the measured device, and a bottom plate for carrying the accelerometer is arranged, that is, the accelerometer can be arranged on the bottom plate, and the bottom plate can be installed perpendicular to the vibration impact direction, so that the sensor of the application can realize the installation of the Z-axis sensitive direction. The first flexible circuit board is connected with the bottom plate, and the conditioning circuit arranged on the bottom plate and / or the mounting plate can receive the sampling signal of the accelerometer and process the sampling signal, output the detection signal obtained after processing, and the detection signal can effectively reflect the vibration and / or impact of the measured device. Moreover, the mounting plate has N layers, and M layers of the N layers are flexible layers, and the M layer flexible layers are connected with the corresponding layers of the first flexible circuit board one by one. Such a design makes it unnecessary to arrange a special joint when the first flexible circuit board is connected with the mounting plate, which is conducive to reducing the volume of the mounting plate. Moreover, since the bottom plate is provided with a groove and the first flexible circuit board can be bent, the mounting plate can be fixed on the bottom plate through the groove after installation, so as to form a three-dimensional board card form. Compared with the design of the conventional scheme in which the accelerometer and the peripheral circuit are welded on a whole PCB, the three-dimensional board card form of the application is conducive to reducing the volume.

[0047] In summary, the sensor of the application supports the installation of the Z-axis sensitive direction, and guarantees the small size of the sensor. Moreover, the mounting plate is provided with a convex part on the side away from the bottom plate after installation, so as to place a stress isolation cover through the convex part. The stress isolation cover can avoid the transmission of excessive stress from the sensor shell to the accelerometer on the bottom plate, which is conducive to avoiding the stress interference on the accelerometer, and can also play an electrical isolation role, improving the insulation between the mounting plate and the sensor shell.

[0048] Moreover, by arranging the calibration circuit for calibrating the detection signal output by the post-conditioning circuit of the accelerometer, the sensitivity and working point of the sensor can be effectively calibrated. In addition, if the calibration circuit is arranged on the calibration plate, the third flexible circuit board can be cut off from the bottom plate after the sensor is calibrated in the production factory, so that a smaller sensor volume can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without any creative labor.

[0050] Figure 1 The schematic diagram of different sensitive directions of the accelerometer;

[0051] Figure 2 A structure schematic view of the sensor circuit board provided in a specific embodiment of the utility model;

[0052] Figure 3 A schematic view of the mounting plate fixed on the bottom plate through the groove in a specific embodiment of the utility model;

[0053] Figure 4 An exploded view and a sectional view of the sensor in a specific embodiment of the utility model;

[0054] Figure 5 A top view and a side view of the sensor circuit board in a specific embodiment of the utility model;

[0055] Figure 6 A structure schematic view of the sensor circuit board in calibration test provided in a specific embodiment of the utility model;

[0056] Figure 7 A structure schematic view of the sensor provided with the second flexible circuit board in a specific embodiment of the utility model;

[0057] Figure 8 A structure schematic view of the sensor provided with the temperature sensor in a specific embodiment of the utility model;

[0058] Figure 9 A structure schematic view of the sensor circuit board provided in another specific embodiment of the utility model;

[0059] Figure 10 A structure schematic view of the analog calibration circuit in a specific embodiment of the utility model;

[0060] Figure 11 A structure schematic view of the digital calibration circuit in a specific embodiment of the utility model;

[0061] Figure 12 A structure schematic view of the conditioning circuit in a specific embodiment of the utility model;

[0062] Figure 13 A structure schematic view of the conditioning circuit in another specific embodiment of the utility model;

[0063] Figure 14 A structure schematic view of the conditioning circuit in still another specific embodiment of the utility model;

[0064] Figure 15 A schematic view of the accelerometer zero output noise in a specific embodiment;

[0065] Figure 16A specific embodiment of the vibration bandwidth extension test result comparison diagram;

[0066] Figure 17 A specific embodiment of the sensor circuit board layout diagram. DETAILED DESCRIPTION

[0067] The core of the utility model provides a kind of sensor and sensor circuit board, and guarantee the small size of sensor, and sensor shell can avoid that excessive stress is transmitted to the accelerometer on bottom plate, it is also favorable to avoid stress interference to accelerometer, can also play the role of electrical isolation, improve the insulation between mounting plate and sensor shell, in addition, effectively realize zero offset calibration and scale factor calibration.

[0068] In order to make the personnel in the technical field better understand the utility model scheme, the utility model is further explained in detail below in combination with drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, not all. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the utility model.

[0069] Please refer to Figure 2 , Figure 2 The structure diagram of the sensor circuit board provided by a specific embodiment of the utility model is shown. The sensor circuit board can include:

[0070] The accelerometer 100 for detecting the vibration and / or impact of the measured equipment;

[0071] The bottom plate 201 for bearing the accelerometer 100; The bottom plate 201 is provided with a groove, so that when installation is completed, the mounting plate 203 is fixed on the bottom plate 201 through the groove.

[0072] The first flexible circuit board 202 connected with the bottom plate 201;

[0073] The mounting plate 203, the mounting plate 203 has N layers, and M layers in N layers are flexible layers, and the M layer flexible layer is connected with the corresponding layer of the first flexible circuit board 202 one by one; Wherein, M and N are positive integers, respectively indicating the number of layers of the first flexible circuit board 202 and the mounting plate 203, and M≤N.

[0074] The conditioning circuit is arranged on the bottom plate 201 and / or the mounting plate 203, and the conditioning circuit is used for receiving the sampling signal of the accelerometer 100 and processing the sampling signal, and outputting the detection signal obtained after processing.

[0075] The mounting plate 203 is provided with a convex portion on the side away from the bottom plate 201 when the mounting is completed, so as to place a stress isolation cover through the convex portion, that is, the side away from the bottom plate 201 when the mounting plate 203 is inserted into the groove of the bottom plate 201 is provided with a convex shape, so as to facilitate the placement of the stress isolation cover, the stress isolation cover can avoid the sensor shell from transmitting excessive stress to the accelerometer 100 on the bottom plate 201, thereby facilitating the avoidance of stress interference on the accelerometer 100, and also playing an electrical isolation role, thereby improving the insulation between the mounting plate 203 and the sensor shell. Figure 4 The stress isolation cover 40 is annular.

[0076] The conditioning circuit is arranged on the bottom plate 201 and / or the mounting plate 203. In actual application, when the space on the mounting plate 203 is sufficient, the conditioning circuit can be arranged on the mounting plate 203, that is, the mounting plate 203 can receive the sampling signal of the accelerometer 100 through the bottom plate 201 and the first flexible circuit board 202, and then process the sampling signal through the conditioning circuit to output the detection signal obtained after processing, which can effectively reflect the acceleration of the measured device, and thus effectively reflect the vibration and / or impact of the measured device.

[0077] In the scheme of the present application, the specific type of the accelerometer 100 can be set and adjusted according to actual needs, for example, can be a capacitive MEMS accelerometer 100, a piezoresistive MEMS accelerometer 100, a resonant MEMS accelerometer 100, etc. In actual application, the capacitive MEMS accelerometer 100 is more commonly used, and the accelerometer 100 is an accelerometer 100 with a sensitive direction of Z axis.

[0078] The sampling signal output by the accelerometer 100 can reflect the acceleration of the measured device, and thus the vibration signal and impact signal of the measured device can be analyzed based on the acceleration of the measured device. Of course, in other specific occasions, the acceleration of the measured device detected by the accelerometer 100 can be used to realize other functions, which does not affect the implementation of the present application.

[0079] In order to effectively fix the accelerometer 100, the bottom plate 201 for bearing the accelerometer 100 is arranged in the scheme of the present application. The bottom plate 201 is usually a hard plate, that is, a commonly used hard PCB. The shape of the bottom plate 201 can be set according to needs, for example Figure 2 In the specific embodiment, the accelerometer 100 is a cuboid, and the bottom plate 201 is circular. In other embodiments, the shape of the bottom plate can be selected as needed, for example, according to the shape of the sensor shell.

[0080] The first flexible circuit board 202 is a soft board, i.e., a flexible circuit board, which is used for circuit wiring, so that the sampling signal of the accelerometer 100 can be transmitted to the mounting plate 203. The bottom plate 201 is connected with the first flexible circuit board 202, and the first flexible circuit board 202 is connected with the mounting plate 203, and the mounting plate 203 is provided with a conditioning circuit.

[0081] Figure 2 In order to facilitate observation, the mounting plate 203 is not inserted into the bottom plate 201. In actual application, when the mounting is completed, reference can be made to Figure 3 is a schematic view of the mounting plate 203 fixed on the bottom plate 201 in an embodiment of the utility model. 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, at this time, a three-dimensional sensor structure is formed, and compared with the design of welding the accelerometer 100 and the peripheral circuit on a whole PCB in the traditional scheme, such a three-dimensional board card form is beneficial to reducing the volume.

[0082] Moreover, the scheme of the present application considers that the first flexible circuit board 202 is a soft board, if the mounting plate 203 is provided as a hard board, the contact part of the first flexible circuit board 202 and the mounting plate 203 needs to be provided with a special interface, which is not conducive to reducing the volume, and is also easy to be damaged due to bending. In view of this, in the scheme of the present application, the mounting plate 203 adopts a soft and hard combination board design, i.e., the first flexible circuit board 202 is an M-layer soft board, and the mounting plate 203 has N layers, M≤N, and M layers in the N layers are flexible layers, so that the M-layer flexible layers in the mounting plate 203 can be connected one by one with the corresponding layers of the first flexible circuit board 202.

[0083] In actual application, the first flexible circuit board 202 will adopt a soft board with flexural resistance, high temperature resistance and high insulation, and the thickness is generally less than 0.2 mm, and it is usually provided as one layer or two layers, and it can be usually connected to the top or bottom of the mounting plate 203, for example, in one occasion, M=2, i.e., the first flexible circuit board 202 is a 2-layer soft board, and the two layers of the first flexible circuit board 202 can be connected with the first layer and the second layer of the mounting plate 203 respectively, and the first layer and the second layer of the mounting plate 203 are both flexible layers, and the first layer of the mounting plate 203 is the top layer. For another example, the two layers of the first flexible circuit board 202 can be connected with the first layer and the second layer of the mounting plate 203 respectively, at this time, the first layer and the second layer of the mounting plate 203 are both flexible layers, and the first layer of the mounting plate 203 is the bottom layer. Of course, in addition to being connected to the top or bottom of the mounting plate 203, in other embodiments, the appropriate M layers in the N layers can be selected as flexible layers according to the needs, and connected one by one with the corresponding layers of the first flexible circuit board 202.

[0084] As can be seen, since the mounting plate 203 adopts the design of the soft and hard combined plate, the mounting plate 203 can be directly connected with the first flexible circuit board 202 without setting a special interface, and the connection position is not easy to be damaged due to bending, thereby ensuring the reliability.

[0085] In actual application, the sensor usually needs to be provided with a sensor shell, Figure 2 and Figure 3 none of which shows the shell, and please refer to Figure 4 , Figure 4 are an exploded view and a sectional view of the sensor in a specific embodiment. As can be seen from Figure 3 , the inner cavity mounting surface of the sensor shell can be effectively matched with the bottom plate 201 to realize the fixation of the bottom plate 201 in the sensor shell. Figure 4 The shell in includes an upper shell and a lower shell matched with the upper shell, and in other embodiments, other shell structures can be adopted according to the needs, which does not affect the implementation of the utility model.

[0086] The specific shape of the mounting plate 203 can be set and adjusted according to the actual needs. In actual application, 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 the space utilization and reduce the volume of the sensor, the side of the mounting plate 203 close to the bottom plate 201 can be in the shape of an arch bridge or other shape which is convenient for insertion into the groove of the bottom plate 201 without affecting the position of the accelerometer 100. In the embodiments of the above application, it can be seen from Figure 2 and Figure 3 that the mounting plate 203 adopts the shape of an arch bridge, that is, the square column with steps on both sides is inserted into the groove of the bottom plate 201.

[0087] Please refer to Figure 5 are a top view and a side view of the sensor circuit board in a specific embodiment, and it can be understood that the mounting plate 203 has not been inserted into the groove of the bottom plate 201, and thus the installation has not been completed. In an embodiment, the side of the mounting plate 203 away from the bottom plate 201 can be provided with a stress isolation hole when the installation is completed. For example, in Figure 5 , the mounting plate 203 is provided with a long strip-shaped stress isolation hole 50, which can play a certain stress isolation and electrical isolation role, and the specific number and size of the stress isolation hole 50 can be set according to the needs. In addition, Figure 5 also shows three mounting holes on the bottom plate 201 for fixing the accelerometer 100, which form a triangle.

[0088] Some conventional accelerometers have high integration, but generally use 1.8V~5V power supply, cannot be directly connected to the input interface of the industrial control or fault detection system, and do not support calibration function. Some accelerometers are calibrated when leaving the factory, but when the downstream sensor application manufacturer purchases the accelerometer for installation, the accelerometer is easily affected by factors such as surface mount installation angle, welding temperature stress, etc., introducing zero error, causing the 0g zero output to change. In addition, although the sensor application manufacturer usually adds a hardware adjustment circuit in the rear circuit of the accelerometer, and can calibrate a single accelerometer within a certain range when the sensor is applied, the calibration accuracy is usually not high, and the calibration efficiency is also not high, and the rear adjustment circuit also introduces certain errors, resulting in lower sensor sensitivity and more serious working point drift.

[0089] In one specific embodiment of the present application, it can further include: a calibration circuit connected with the accelerometer 100, used for calibrating the detection signal output by the conditioning circuit of the rear stage of the accelerometer 100, that is, calibrating the sensor through the calibration circuit.

[0090] The calibration circuit can be arranged on the calibration fixture, or arranged on the mounting plate 203, or arranged on the calibration plate 204.

[0091] When the calibration circuit is arranged on the calibration fixture, the sensor circuit board further includes a second flexible circuit board connected with the bottom plate 201, and the second flexible circuit board is provided with a calibration circuit interface, and the calibration fixture is connected with the second flexible circuit board through the calibration circuit interface during calibration.

[0092] When the calibration circuit is arranged on the calibration plate 204, the calibration plate 204 is connected with the bottom plate 201 through the third flexible circuit board 205, and after completing the calibration test, the connection between the third flexible circuit board 205 and the bottom plate 201 is cut off, that is, the third flexible circuit board 205 and the bottom plate 201 are cut off, and the two components are separated in physical connection.

[0093] The calibration plate 204 has P layers, and Q layers in the P layers are flexible layers, and the Q layer flexible layers are connected with the corresponding layers of the third flexible circuit board 205 one by one, wherein P and Q are both positive integers, representing the number of layers of the third flexible circuit board 205 and the calibration plate 204 respectively, and Q≤P.

[0094] 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.

[0095] See also Figure 6 This is a schematic diagram of the sensor circuit board during calibration testing in one 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.

[0096] See also Figure 7 This is a schematic diagram of a sensor structure with a second flexible circuit board. Figure 7In the embodiment, the calibration circuit is arranged on the calibration fixture, and the calibration fixture is connected with the bottom plate 201 through the second flexible circuit board 206 during calibration, that is, the second flexible circuit board 206 needs to be connected with the bottom plate 201. In the embodiment, the calibration circuit is arranged on the calibration fixture, and the second flexible circuit board 206 is provided with a calibration circuit interface, so that the calibration circuit on the calibration fixture is connected with the sensor circuit board in the circuit. It can be 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 soft board, when the calibration test is completed, a certain space can be left in the sensor shell for placing the second flexible circuit board 206 during installation, so it is not necessary to cut off the second flexible circuit board 206 after calibration test. Of course, even if the second flexible circuit board 206 is a soft board and occupies a small space, there is still a certain space occupation, so in actual application, in the occasion where the size of the sensor is required to be strict, the embodiment described above is usually adopted, that is, the calibration circuit is arranged on the calibration plate 204, and the calibration plate 204 and the third flexible circuit board 205 are cut off by the plate cutting machine.

[0097] In some embodiments, the calibration circuit can be directly arranged on the mounting plate 203, which has the advantage of not needing to be cut off, but increases the area of the mounting plate 203 to some extent, and can be applied to occasions where the size of the sensor is not particularly high.

[0098] In one specific embodiment of the present application, the accelerometer 100 is fixed on the top of the bottom plate 201.

[0099] The mounting plate 203 is a mounting plate 203 with a pre-designed concave structure, so that after the mounting plate 203 is fixed on the bottom plate 201 through the groove, a containing cavity is formed between the mounting plate 203 and the bottom plate 201 to contain the accelerometer 100 through the containing cavity.

[0100] The sensor further comprises a temperature sensor, and the temperature sensor is fixed on the bottom of the bottom plate 201 through a fixing component.

[0101] The embodiment considers that in some occasions, in addition to the demand for detecting acceleration, the sensor also has the demand for detecting temperature, so in the embodiment, the accelerometer 100 can be fixed on the top of the bottom plate 201, and the temperature sensor is also arranged and fixed on the bottom of the bottom plate 201 through the fixing component. Figure 8 is a schematic diagram of a sensor structure provided with a temperature sensor in one specific embodiment, Figure 8 and Figure 4The temperature sensor 80 is fixed to the bottom of the bottom plate 201 by fixing components, instead of being directly fixed to the bottom of the bottom plate 201, because in actual application, the preset temperature measuring position and the preset acceleration measuring position are usually at a certain distance, and in addition, this can also avoid the interference of high / low temperature on the accelerometer 100 to a certain extent. Figure 8 In this embodiment, the temperature sensor 80 is fixed to the bottom of the bottom plate 201 by three cylindrical fixing components.

[0102] In addition, in this embodiment, the mounting plate 203 is a mounting plate 203 with a preset concave structure, for example, specifically in the form of an arch bridge as described above. The concave structure is arranged on the designated side close to the bottom plate 201, so that after the mounting plate 203 is fixed on the bottom plate 201 through the groove, due to the existence of the concave structure, a containing 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 being beneficial to reducing the volume of the sensor.

[0103] In one specific embodiment of the present application, the groove provided on the bottom plate 201 includes a first groove and a second groove;

[0104] The mounting plate 203 has a first connecting end and a second connecting end, and the first connecting end is inserted into the first groove, and the second connecting end is inserted into the second groove;

[0105] 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;

[0106] Or;

[0107] 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.

[0108] This embodiment takes into account that in order to ensure stability, the groove provided on the bottom plate 201 can be multiple, for example, in this embodiment, it specifically includes a first groove and a second groove, and correspondingly, the mounting plate 203 needs to have a corresponding first connecting end and a second connecting end, so as to be respectively inserted into the first groove and the second groove.

[0109] And this embodiment takes into account that the mortise and tenon structure is beneficial to ensuring the reliability of the connection, so the L-shaped structure can be used to realize the mortise and tenon connection. Taking the first connecting end as an example, please refer to 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 a 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.

[0110] 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.

[0111] The installation position 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 this utility model, 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.

[0112] 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.

[0113] For example, in one specific embodiment of this utility model, the analog calibration circuit may include: a first voltage divider circuit and a second voltage divider circuit;

[0114] The first voltage dividing circuit is connected with the scale factor compensation interface of the accelerometer 100, and is used for adjusting the excitation voltage amplitude applied to the differential capacitance of the accelerometer 100 by controlling the voltage of the scale factor compensation interface, so as to calibrate the sensitivity of the sensor on which the sensor circuit board is located by adjusting the scale factor calibration of the accelerometer 100.

[0115] The second voltage dividing circuit is connected with the zero offset compensation interface of the accelerometer 100, and is used for calibrating the zero offset of the accelerometer 100 by adjusting the direct current bias of the accelerometer 100 through controlling the voltage of the zero offset compensation interface, so as to calibrate the working point of the sensor.

[0116] 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. The zero offset, also known as the offset, is the direct current output of the accelerometer when the acceleration is 0g, and determines the working point of the sensor. The unit is usually mg or the corresponding electric quantity output value, and the zero offset will affect the static working point of the sensor, that is, affect the output voltage value (usually in units of V) of the sensor under static state.

[0117] Since the accelerometer 100 itself may have accuracy problems, and in the process of being welded to the circuit board, the sensitivity and zero offset of the accelerometer 100 will be affected, and then the output of the conditioning circuit will be affected, and finally the sensitivity and working point of the sensor will be affected. Therefore, in order to improve the sensitivity and working point of the sensor, the output of the conditioning circuit needs to be calibrated, that is, the sensitivity and working point of the sensor on which the sensor circuit board is located are calibrated.

[0118] The implementation considers that the excitation voltage amplitude of the differential capacitor of the accelerometer 100 will affect the scale factor of the accelerometer 100, and thus the scale factor of the accelerometer 100 can be adjusted by adjusting the excitation voltage amplitude of 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, and thus in the implementation, the first voltage dividing circuit is connected to the scale factor compensation interface of the accelerometer 100, and the voltage of the scale factor compensation interface is controlled, so that the scale factor of the accelerometer 100 can be adjusted. It can be understood that when the scale factor of the accelerometer 100 is adjusted, the sensitivity of the output of the conditioning circuit needs to be detected, that is, the sensitivity of the output of the conditioning circuit is adjusted by adjusting the scale factor of the accelerometer 100, so that the sensitivity of the output of the conditioning circuit is calibrated, that is, the sensor is calibrated. When the implementation is adopted, the accelerometer 100 needs to be pre-set according to the functional requirements of the application, so that the accelerometer 100 has the scale factor compensation interface required by the application, and the excitation voltage amplitude of the differential capacitor of the accelerometer 100 can be adjusted based on the voltage of the scale factor compensation interface.

[0119] The implementation considers that in addition to the scale factor, the accelerometer 100 can also have a zero offset due to itself and installation process, and thus the implementation can also adjust the zero offset of the accelerometer 100, so that the working point of the output of the conditioning circuit is calibrated, and thus the working point of the sensor is calibrated. Specifically, in the implementation, the second voltage dividing circuit is connected to the zero offset compensation interface of the accelerometer 100, and the voltage of the zero offset compensation interface is controlled, so that the DC bias of the accelerometer 100 is adjusted, the zero offset of the accelerometer 100 is adjusted, and thus the working point of the output of the conditioning circuit is calibrated, that is, the working point of the sensor is calibrated. It can be understood that when the implementation is adopted, the accelerometer 100 needs to be pre-set according to the functional requirements of the application, so that the accelerometer 100 has the zero offset compensation interface required by the application, and the DC bias of the accelerometer 100 can be adjusted based on the voltage of the zero offset compensation interface to adjust the zero offset of the accelerometer 100.

[0120] The specific structure of the first voltage dividing circuit and the second voltage dividing circuit can be set as needed, and the voltage control of the corresponding interface can be realized. For example, refer to Figure 10For a structure schematic diagram of the analog calibration circuit in the specific embodiment, the first voltage dividing circuit can include a first voltage dividing device and a second voltage dividing device. A first end of the first voltage dividing device is connected with a first power supply end Vref1, a second end of the first voltage dividing device is connected with a first end of the second voltage dividing device and a scale factor compensation interface respectively, and a second end of the second voltage dividing device is grounded;

[0121] The first voltage dividing device and / or the second voltage dividing device is a voltage dividing device with adjustable parameters itself, so as to control the voltage of the scale factor compensation interface;

[0122] The second voltage dividing circuit includes a third voltage dividing device and a fourth voltage dividing device, a first end of the third voltage dividing device is connected with a second power supply end Vref2, a second end of the third voltage dividing device is connected with a first end of the fourth voltage dividing device and a zero offset compensation interface respectively, and a second end of the fourth voltage dividing device is grounded;

[0123] The third voltage dividing device and / or the fourth voltage dividing device is a voltage dividing device with adjustable parameters itself, so as to control the voltage of the zero offset compensation interface.

[0124] In the specific embodiment, the first voltage dividing circuit is composed of the first voltage dividing device and the second voltage dividing device, and the structure is simple, and the first voltage dividing device and / or the second voltage dividing device needs to be a voltage dividing device with adjustable parameters itself, so as to control the voltage of the scale factor compensation interface. Figure 10 In the specific embodiment, the first voltage dividing device is denoted as R11, which can be a fixed resistor or a resistor with adjustable resistance value, the second voltage dividing device is a variable resistance diode D11, and the scale factor compensation interface is denoted as Vsens.

[0125] Similarly, the second voltage dividing circuit is composed of the third voltage dividing device and the fourth voltage dividing device, and the structure is simple, and the third voltage dividing device and / or the fourth voltage dividing device needs to be a voltage dividing device with adjustable parameters itself, so as to control the voltage of the zero offset compensation interface. Figure 10 In the specific embodiment, the third voltage dividing device and the fourth voltage dividing device are denoted as R12 and R13 respectively, and the zero offset compensation interface is denoted as Vbisa. One of the third voltage dividing device and the fourth voltage dividing device or both of them are resistors with adjustable resistance value, so as to control the voltage of the zero offset compensation interface. In addition, in actual application, the precision of voltage division based on the variable resistance diode D11 is usually higher than that of the adjustable resistor.

[0126] In a specific embodiment of the utility model, refer to Figure 11 The digital calibration circuit includes a controller 101 connected with the accelerometer 100, used for calibrating the sensitivity of the sensor on which the sensor circuit board is located by controlling the value of the first register in the accelerometer 100, and used for calibrating the working point of the sensor by controlling the value of the second register in the accelerometer 100.

[0127] Specifically, the controller 10 can control the value of the first register in the accelerometer 100, so as to control the amplification multiple of the gain circuit in the accelerometer 100 through the value of the first register, to calibrate the sensitivity of the sensor where the sensor circuit board is located.

[0128] The controller 10 can control the value of the second register in the accelerometer 100, so as 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, to calibrate the working point of the sensor.

[0129] In this embodiment, the controller 101 is used for digital calibration, and the controller 101 can usually be an MCU. Specifically, considering that there are multiple gain circuits in the accelerometer 100, the amplification multiple of these gain circuits is controlled through the value of the first register, so as to amplify or reduce the output voltage of the circuit, to realize the adjustment of the scale factor, and therefore the controller 101 controls the value of the first register in this embodiment, to adjust the scale factor of the accelerometer 100, so as to realize the calibration of the sensitivity of the sensor where the sensor circuit board is located. In actual application, 1 Byte byte is set, and the adjustable range of the gain circuit is 1-256 times.

[0130] The accelerometer 100 is arranged with multiple groups of differential capacitances, which can be respectively connected in parallel to the upper plate static capacitance or the lower plate static capacitance of the accelerometer 100, and 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 can be controlled through the value of the second register, so as to realize the zero offset adjustment of the accelerometer 100 through the adjustment of the static capacitance, to realize the working point calibration of the sensor.

[0131] In addition, it also needs to be explained that when the controller 101 is used for the calibration of the accelerometer 100, the scale factor compensation interface and the zero offset compensation interface can also be controlled by voltage, to realize the calibration of the sensor where the sensor circuit board is located, for example Figure 11In the embodiment, the controller 101 not only connects the accelerometer 100 through the SPI interface (MCLK and MOSI), but also connects the scale factor compensation interface (Vsens) and the zero offset compensation interface (Vbias) through the DAC0 and DAC1 interface. In practical application, the voltage control through the scale factor compensation interface and the zero offset compensation interface is usually used to realize the coarse adjustment of calibration, and the control of the value of the first register and the value of the second register is used to realize the fine adjustment of calibration. In addition, in some other embodiments, one of the scale factor compensation interface (Vsens) and the zero offset compensation interface (Vbias) can be controlled by the controller 101, and the other can be selected to be a fixed voltage value or can be selected to be controlled by the analog calibration circuit. That is, if necessary, the combination of the analog calibration circuit and the digital calibration circuit can be used to realize calibration, and the present application does not limit this. For example, in the embodiment described below Figure 14 , the voltage of the zero offset compensation interface (Vbias) is controlled by the third voltage dividing device R12 and the fourth voltage dividing device R13, the voltage of the scale factor compensation interface (Vsens) is fixed, and the controller 101 is used to calibrate the accelerometer 100. Of course Figure 14 , the controller 101 is not shown in the embodiment.

[0132] As described above, the calibration circuit can be arranged on the second flexible circuit board 206, or arranged on the mounting plate 203, or arranged on the calibration plate 204. It can be understood that if the analog calibration circuit is used, the calibration circuit can be arranged on the second flexible circuit board 206 or the mounting plate 203. If the digital calibration circuit is used, and the digital calibration circuit is arranged on the second flexible circuit board 206 or the mounting plate 203, the relevant calibration parameters obtained through calibration can be stored in the digital calibration circuit, for example, stored in the flash of the MCU. If the digital calibration circuit is arranged on the calibration plate 204, since the calibration plate 204 will be cut off after calibration, the relevant calibration parameters obtained through calibration need to be stored in the accelerometer 100, for example, stored in the OTP (a kind of non-volatile storage area) of the accelerometer 100, and in this case, the voltages of the scale factor compensation interface and the zero offset compensation interface of the accelerometer 100 are usually set to fixed values, for example Figure 13 , in which the voltages of the scale factor compensation interface and the zero offset compensation interface of the accelerometer 100 are fixed, and at this time, the controller can be arranged on the calibration plate 204, and the calibration plate 204 will be cut off after calibration, which effectively reduces the volume of the sensor and improves the reliability. In addition, Figure 12 , the controller 101 is not shown in the embodiment.

[0133] The sampling signal transmitted by the accelerometer 100 needs to be transmitted to the conditioning circuit of the mounting plate 203, processed by the conditioning circuit, and the signal after processing is the detection signal obtained by the sensor. The specific circuit structure of the conditioning circuit can be set according to actual needs, for example, voltage amplification, current-voltage conversion and other operations can be performed through the conditioning circuit.

[0134] In one specific embodiment of the present application, reference can be made to Figure 12 , which is a structural schematic diagram of the conditioning circuit in a specific embodiment. The conditioning circuit can include:

[0135] The filter circuit 301 connected with the accelerometer 100 is used to filter the sampling signal output by the accelerometer 100 and expand the vibration frequency detection range.

[0136] The signal conversion circuit 302 connected with the filter circuit 301 is used to amplify the output of the filter circuit, or amplify the output of the filter circuit 301 and convert voltage or current.

[0137] The interface protection circuit 303 connected with 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.

[0138] This kind of embodiment considers 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 the sensitivity and noise, the inherent frequency design of part of the accelerometer 100 is less than 30kHz, which cannot meet the demand of use bandwidth above 10kHz. In this kind of embodiment, the filter circuit 301 is connected at the output end of the accelerometer 100 for filtering, which is usually a first-order RC low-pass filter circuit. It not only can filter high-frequency noise, but also can suppress the resonance peak, thereby expanding the use bandwidth of the accelerometer 100, that is, effectively expanding the vibration frequency detection range.

[0139] Figure 12 The calibration circuit 304 and the power supply circuit 305 connected with the accelerometer 100 are also shown in the figure. The power supply circuit 305 is connected with the calibration circuit 304, the signal conversion circuit 302 and the accelerometer 100 respectively, so as to provide power for the devices / circuits that need power supply in the calibration circuit 304, the signal conversion circuit 302 and the accelerometer 100, and the voltage levels required by different devices / circuits can be different. In addition, since the filter circuit 301 adopts a passive filter circuit, Figure 12 The power supply circuit 305 is not connected with the filter circuit 301 in the figure, and in other embodiments, an active filter circuit can be used according to actual needs, and the power supply circuit 305 provides the required power for it.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] By applying the technical solution provided in this utility model embodiment, 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.

[0144] Specifically, the accelerometer can detect the vibration and / or impact of the measured device, and a bottom plate for carrying the accelerometer is arranged, that is, the accelerometer can be arranged on the bottom plate, and the bottom plate can be installed perpendicular to the vibration impact direction, so that the sensor of the application can realize the installation of the Z-axis sensitive direction. The first flexible circuit board is connected with the bottom plate, and the conditioning circuit arranged on the bottom plate and / or the mounting plate can receive the sampling signal of the accelerometer and process the sampling signal, output the detection signal obtained after processing, and the detection signal can effectively reflect the vibration and / or impact of the measured device. Moreover, the mounting plate has N layers, and M layers in the N layers are flexible layers, and the M flexible layers are connected one by one with the corresponding layers of the first flexible circuit board. Such a design makes it unnecessary to arrange a special joint when the first flexible circuit board is connected with the mounting plate, which is conducive to reducing the volume of the mounting plate. Moreover, since the bottom plate is provided with a groove and the first flexible circuit board can be bent, the mounting plate can be fixed on the bottom plate through the groove after installation, so as to form a three-dimensional board card form. Compared with the design of the conventional scheme in which the accelerometer and the peripheral circuit are welded on a whole PCB, the three-dimensional board card form of the application is conducive to reducing the volume.

[0145] As can be seen from the above, the sensor of the application supports Z-axis sensitive direction installation, and guarantees the small size of the sensor. Moreover, the mounting plate is provided with a convex portion on the side away from the bottom plate after installation, so as to place a stress isolation cover through the convex portion. The stress isolation cover can avoid the transmission of excessive stress from the sensor shell to the accelerometer on the bottom plate, so as to avoid the stress interference on the accelerometer, and also has the effect of electrical isolation, thereby improving the insulation between the mounting plate and the sensor shell.

[0146] In a specific embodiment in actual application, the overall circuit board size of the application can meet the requirements of less than or equal to 12.5 mm in diameter and less than 16 mm in height, and can meet the installation requirements of a small sensor (sensor diameter less than or equal to 18.5 mm). After installation of the sensor, the vibration and impact response is good, the vibration sensitivity distribution range reaches 99.05%~102.22% of 20 mV / g, and the impact SV value detection range is 0~10000 SV.

[0147] In Figure 13For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V.

[0148] For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V. Figure 13 For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V.

[0149] For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V. Figure 15 For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V. Figure 15 For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V.

[0150] For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V. Figure 16 For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V. Figure 16 For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V.

[0151] For example, in an embodiment, 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 multiple of the gain circuit in the accelerometer 100, adjust the scale factor, for example, the step of adjustment is 0.025 mV / g, and the adjustment range is 10 mV / g ± 10 mV / g. Through the value of the second register, the static differential capacitance value is compensated, so that the zero output of the accelerometer 100 is adjusted, for example, the step of adjustment is 25 mV, and the adjustment range is 2.5 V ± 1.5 V.

[0152] In the specific embodiment, when the sensor circuit board of the present application is calibrated and installed, the sensor circuit board can be horizontally placed into the calibration fixture for calibration by the calibration fixture. Then the third flexible circuit board and the calibration board on the sensor circuit board are cut off. Finally, after the mounting plate is fixed on the bottom plate through the groove provided on the bottom plate, the sensor circuit board is placed into the sensor housing.

[0153] The calibration circuit provided in the sensor circuit board can be the analog calibration circuit or the digital calibration circuit described above, and the calibration principle can refer to the description above, which will not be repeated here. And here the calibration circuit is provided on the calibration board, and the calibration board is connected with 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, so as to cut off the third flexible circuit board and the calibration board, so that the sensor circuit after calibration has a small volume, which ensures the small volume of the sensor. For the scheme using the second flexible circuit board, the calibration fixture can also be used for calibration.

[0154] The calibration fixture can be a calibration fixture for batch calibration of sensor circuit boards, so that after the sensor circuit board is horizontally placed into the calibration fixture, batch calibration of multiple sensor circuit boards is carried out by the calibration fixture to improve the calibration efficiency. In practical application, multiple sensor circuit boards can be horizontally placed into the calibration fixture, and batch calibration can be realized at one time through the calibration interface, which is beneficial to improve the calibration efficiency and the qualification rate. For example, motion control of the calibration fixture is required during calibration, at this time, the corresponding sensor circuit board can be calibrated one by one. For details, please refer to Figure 17As a layout diagram of the sensor circuit board in the embodiment, the left side is the scheme provided with the calibration plate, and the right side is the scheme provided with the second flexible circuit board. As described above, in the scheme of the present application, when calibration is performed, the calibration is not performed separately after the accelerometer is produced, but the board card connection of the accelerometer, the bottom plate, the mounting plate and the like is completed, that is, the sensor circuit board is generated and connected, and then placed horizontally into the calibration jig for calibration, that is, the entire sensor circuit board is calibrated together, so that the calibration accuracy is improved. The calibration process can be single sensor circuit board calibration, or multiple circuit boards can be calibrated simultaneously through the calibration jig. In this embodiment, it is a layout diagram of the sensor circuit board to meet the horizontal batch calibration of multiple sensor circuit boards through the calibration jig. In addition, the stress isolation cover is provided for the accelerometer in the sensor circuit board, which is usually before the sensor circuit board is assembled, that is, before the mounting plate is fixed on the bottom plate through the groove provided on the bottom plate. After the mounting plate is fixed on the bottom plate through the groove provided on the bottom plate, it can be placed in the sensor shell.

[0155] It should also be noted that in this application, relationship terms such as first and second 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 the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, article or equipment including the element.

[0156] Those skilled in the art can further understand that the units and algorithm steps of each example described in combination with the embodiments disclosed in the present application can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different ways to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application. The principles and implementation modes of the present application are described by using specific examples in the present application. The above description of the examples is only to help understand the technical solutions and core ideas of the present application. It should be pointed out that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A sensor circuit board, characterized by, The application relates to a sensor circuit board for detecting vibration and / or impact of a device under test, comprising: an accelerometer for detecting vibration and / or impact of a device under test; a bottom plate for carrying the accelerometer; a first flexible circuit board connected with the bottom plate; an installation plate having N layers, and M layers of the N layers are flexible layers, and the M layers of flexible layers are connected with corresponding layers of the first flexible circuit board one by one; wherein M and N are positive integers, respectively representing the number of layers of the first flexible circuit board and the installation plate, and M<=N; a conditioning circuit arranged on the bottom plate and / or the installation plate, and the conditioning circuit is used for receiving a sampling signal of the accelerometer and processing the sampling signal, and outputting a detection signal obtained after processing; a groove is arranged on the bottom plate, so that the installation plate is fixed on the bottom plate through the groove after installation; a convex part is arranged on a side of the installation plate away from the bottom plate after installation, so that a stress isolation cover is placed through the convex part. The accelerometer is an accelerometer with a sensitive direction of a Z axis. A stress isolation hole is arranged on a side of the installation plate away from the bottom plate after installation. The application further comprises: a calibration circuit connected with the accelerometer and used for calibrating the detection signal, the calibration circuit is arranged on a calibration jig, or arranged on the installation plate, or arranged on a calibration plate; when the calibration circuit is arranged on the calibration jig, the sensor circuit board further comprises a second flexible circuit board connected with the bottom plate, the second flexible circuit board is provided with a calibration circuit interface, and the calibration jig is connected with the second flexible circuit board through the calibration circuit interface during calibration; when the calibration circuit is arranged on the calibration plate, the calibration plate is connected with the bottom plate through a third flexible circuit board, and the connection between the third flexible circuit board and the bottom plate is cut off after completion of calibration test; the calibration plate has P layers, and Q layers of the P layers are flexible layers, and the Q layers of flexible layers are connected with corresponding layers of the third flexible circuit board one by one, wherein P and Q are positive integers, respectively representing the number of layers of the third flexible circuit board and the calibration plate, and Q<=P. The accelerometer is fixed on the top of the bottom plate; the installation plate is an installation plate with a preset concave structure, so that after the installation plate is fixed on the bottom plate through the groove, a containing cavity is formed between the installation plate and the bottom plate, and the accelerometer is contained through the containing cavity. The application further comprises: a temperature sensor, and the temperature sensor is fixed on the bottom of the bottom plate through a fixing part. The groove arranged on the bottom plate comprises a first groove and a second groove; the installation plate has a first connecting end and a second connecting end, and 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 a thickness direction for matching the first groove, and the second connecting end has an L-shaped structure in a thickness direction for matching the second groove; or ​ 2. The sensor circuit board of claim 1, wherein, ​ 3. The sensor circuit board of claim 1, wherein, ​ 4. The sensor circuit board of claim 1, wherein, ​ ​ ​ ​ ​ 5. The sensor circuit board of claim 1, wherein, ​ ​ 6. The sensor circuit board of claim 5, wherein, ​ ​ 7. The sensor circuit board of claim 1, wherein, ​ ​ ​ ​ The first connecting end has an L-shaped structure in the length direction for matching with the first groove, and the second connecting end has an L-shaped structure in the length direction for matching with the second groove.

8. The sensor circuit board of claim 1, wherein, The conditioning circuit comprises: a filter circuit connected with the accelerometer, for filtering the sampling signal output by the accelerometer and extending the vibration frequency detection range; a signal conversion circuit connected with the filter circuit, for amplifying the output of the filter circuit, or for amplifying and voltage or current conversion of the output of the filter circuit; an interface protection circuit connected with the signal conversion circuit for anti-interference, and the output of the interface protection circuit is the output of the conditioning circuit, and the detection signal obtained after output processing.

9. The sensor circuit board according to any one of claims 1 to 8, characterized in that Further comprising: a calibration circuit connected with the accelerometer, for calibrating the detection signal, the calibration circuit being an analog calibration circuit based on an analog circuit for calibration, or a digital calibration circuit based on a controller for calibration.

10. The sensor circuit board of claim 9, wherein, The analog calibration circuit comprises: a first voltage dividing circuit and a second voltage dividing circuit; the first voltage dividing circuit is connected with a scale factor compensation interface of the accelerometer, for adjusting the excitation voltage amplitude of the differential capacitance applied to the accelerometer by controlling the voltage of the scale factor compensation interface, so as to calibrate the sensitivity of the sensor by adjusting the scale factor of the accelerometer; the second voltage dividing circuit is connected with a zero offset compensation interface of the accelerometer, for adjusting the direct current bias of the accelerometer by controlling the voltage of the zero offset compensation interface, so as to calibrate the working point of the sensor.

11. The sensor circuit board of claim 10, wherein, The first voltage dividing circuit comprises a first voltage dividing device and a second voltage dividing device; a first end of the first voltage dividing device is connected with a first power supply end, a second end of the first voltage dividing device is respectively connected with a first end of the second voltage dividing device and the scale factor compensation interface, and a second end of the second voltage dividing device is grounded; the first voltage dividing device and / or the second voltage dividing device is a voltage dividing device with adjustable parameters itself, so as to control the voltage of the scale factor compensation interface; the second voltage dividing circuit comprises a third voltage dividing device and a fourth voltage dividing device, a first end of the third voltage dividing device is connected with a second power supply end, a second end of the third voltage dividing device is respectively connected with a first end of the fourth voltage dividing device and the zero offset compensation interface, and a second end of the fourth voltage dividing device is grounded; the third voltage dividing device and / or the fourth voltage dividing device is a voltage dividing device with adjustable parameters itself, so as to control the voltage of the zero offset compensation interface.

12. The sensor circuit board of claim 9, wherein, The digital calibration circuit comprises a controller connected with the accelerometer, for calibrating the sensitivity of the sensor by controlling the value of a first register in the accelerometer, and for calibrating the working point of the sensor by controlling the value of a second register in the accelerometer.

13. A sensor, characterized by The sensor circuit board comprises any one of claims 1 to 12.

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