Capacitive ultrasonic sensor

Abstract

The invention relates to a capacitive ultrasonic sensor, which comprises a first planar electrode and a second planar electrode which are oppositely arranged, the first planar electrode and the second planar electrode are at least partially attached and are insulated to form a stable planar capacitor; wherein the first planar electrode is a conductive film. According to the ultrasonic sensor, the first planar electrode and the second planar electrode are used for replacing a piezoelectric ceramic piece to form a planar capacitor, and the technical defects caused by the piezoelectric ceramic piece production technology are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a capacitive ultrasonic sensor. Background Art

[0002] Ultrasonic sensor is a sensor that uses sound wave medium to perform non-contact and wear-free detection of the object being detected.

[0003] The ultrasonic sensor in the related technology mainly includes a metal shell and a piezoelectric ceramic sheet installed in the metal shell. The piezoelectric ceramic sheet can both emit and receive ultrasonic waves. However, the current production technology of piezoelectric ceramic sheets has defects such as many and complex process steps, low yield, poor consistency of the center frequency of piezoelectric ceramics, etc., which leads to problems such as low production capacity, high cost, and serious material waste. Summary of the invention

[0004] The technical problem to be solved by the present invention is that there are defects in the production technology of piezoelectric ceramic sheets in the related art, and an improved capacitive ultrasonic sensor is provided.

[0005] The technical solution adopted by the present invention to solve the technical problem is: constructing a capacitive ultrasonic sensor, including a first planar electrode and a second planar electrode arranged opposite to each other;

[0006] The first planar electrode and the second planar electrode are at least partially attached and insulated to form a stable planar capacitor;

[0007] Wherein, the first planar electrode is a conductive film.

[0008] In some embodiments, the conductive film includes a metal film or a graphite film.

[0009] In some embodiments, the thickness of the conductive film is 1 μm-500 μm.

[0010] In some embodiments, the second planar electrode (2) comprises a conductive metal plate, and an insulating layer is provided on the side of the metal plate facing the first planar electrode (1).

[0011] In some embodiments, the second planar electrode includes a PCB board, the PCB board is provided with a conductive layer located on a side facing the first planar electrode, and a pad electrically connected to the conductive layer.

[0012] In some embodiments, an insulating layer is provided on a surface of the conductive layer facing the first planar electrode.

[0013] In some embodiments, the insulating layer includes an insulating oil layer and / or a silk-screen layer disposed on the surface of the conductive layer.

[0014] In some embodiments, the surface of the insulating layer facing the first planar electrode is arranged in a concave-convex manner.

[0015] In some embodiments, the capacitive ultrasonic sensor includes a cylindrical housing with a step provided therein, and the first planar electrode is placed on the step.

[0016] In some embodiments, the capacitive ultrasonic sensor includes a connecting electrode;

[0017] The connecting electrode is a planar structure and is electrically connected to the first planar electrode. The connecting electrode is located at the periphery of the second planar electrode and is attached to a surface of the first planar electrode that is opposite to the step.

[0018] In some embodiments, the capacitive ultrasonic sensor includes a pressure ring that abuts against a surface of the connecting electrode facing away from the first planar electrode, and the periphery of the pressure ring is clamped on the inner side of the shell to press the connecting electrode and the first planar electrode onto the step.

[0019] In some embodiments, the capacitive ultrasonic sensor includes a sealing member embedded in a surface of the pressure ring facing the connecting electrode.

[0020] In some embodiments, the pressure ring is provided with a liquid injection hole for injecting glue, and the glue is solidified and formed in one or more gaps formed by at least two combinations of the pressure ring, the seal, the connecting electrode and the first planar electrode in the housing.

[0021] In some embodiments, the capacitive ultrasonic sensor includes a compression spring, which is relatively fixed to a side of the second planar electrode facing away from the first planar electrode and abuts against the second planar electrode to apply a force to the second planar electrode to make it close to the first planar electrode.

[0022] In some embodiments, the capacitive ultrasonic sensor further includes a main control board, which is mounted on a side of the pressure ring facing away from the connecting electrode and is electrically connected to the second planar electrode and the connecting electrode.

[0023] In some embodiments, the capacitive ultrasonic sensor further includes a mesh cover mounted on an end of the housing close to the first planar electrode.

[0024] In some embodiments, the capacitive ultrasonic sensor further includes a back cover mounted on an end of the housing away from the first planar electrode and blocking an opening of the end of the housing away from the first planar electrode.

[0025] In some embodiments, a second clamping block is provided on the inner circumference of the housing;

[0026] A buckle slot is provided on the outer periphery of the back cover, the buckle slot has a notch, and an interior of a slot connected to the notch and located on one side of the notch in the circumferential direction of the back cover;

[0027] The back cover is inserted into the shell, and the second clamping block is relatively moved to the inside of the slot by rotation, so as to limit the back cover from being separated from the shell.

[0028] The implementation of the present invention has the following beneficial effects: the first planar electrode and the second planar electrode of the present invention form a planar capacitor. When a pulse electric field or an alternating electric field of a certain frequency is applied to the planar capacitor, the planar capacitor can vibrate up and down to generate ultrasonic waves, and the ultrasonic waves are emitted to the side of the first planar electrode away from the second planar electrode. Alternatively, the planar capacitor vibrates under the action of external ultrasonic waves, and the capacitance value formed between the first planar electrode and the second planar electrode will change with the vibration, thereby generating a detectable electrical signal, and the electrical signal is emitted to the side of the first planar electrode away from the second planar electrode.

[0029] The ultrasonic sensor of the present invention utilizes the first planar electrode and the second planar electrode to replace the piezoelectric ceramic sheet to form a planar capacitor, thereby avoiding the technical defects caused by the production technology of the piezoelectric ceramic sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0031] Figure 1 is a longitudinal cross-sectional view of the structure of the ultrasonic sensor of the present invention in Example 1;

[0032] Figure 2 is a schematic diagram of the structure of the second planar electrode in some embodiments of the present invention in a top view;

[0033] Figure 3 is a structural explosion diagram of the ultrasonic sensor of the present invention in Example 2;

[0034] Figure 4 is a longitudinal cross-sectional view of the structure of the ultrasonic sensor of the present invention in Example 2;

[0035] Figure 5 is a schematic diagram of the structure of the housing in some embodiments of the present invention;

[0036] Figure 6 is a schematic diagram of a structure in which a first planar electrode is mounted on a housing in some embodiments of the present invention;

[0037] Figure 7 is a schematic diagram of a structure in which a connecting electrode is mounted on a first planar electrode in some embodiments of the present invention;

[0038] Figure 8 is a schematic diagram of a structure in which a pressure ring structure is installed on a connecting electrode in some embodiments of the present invention;

[0039] Fig. 9 is a schematic diagram of the structure of a pressure ring in some embodiments of the present invention;

[0040] Fig.10 is a schematic diagram of a structure in which a second planar electrode and a compression spring member are mounted on a compression ring in some embodiments of the present invention;

[0041] Fig.11 is a schematic diagram of the structure of the compression spring member at a first angle in some embodiments of the present invention;

[0042] Fig.12 is a schematic diagram of the structure of the compression spring member at a second angle in some embodiments of the present invention;

[0043] Fig.13 is a schematic diagram of a structure in which a main control board is installed in a housing in some embodiments of the present invention;

[0044] Fig.14 It is a structural cross-sectional view of a back cover mounted on a housing in some embodiments of the present invention.

[0045] Reference numerals:

[0046] Ultrasonic sensor 100;

[0047] A first planar electrode 1;

[0048] Second planar electrode 2; pad 21; silk screen layer 22;

[0049] Housing 3; first end 31; second end 32; step 33; stopper 34; first clamping block 35; second clamping block 36; stopper groove 37;

[0050] Connecting electrode 4; through slot 41; through hole pad 42;

[0051] Pressing structure 5; pressing ring 51; ring body 511; first ring segment 5111; second ring segment 5112; avoidance groove 512; inclined wedge 513; inclined surface 5131; force-bearing surface 5132; mounting groove 514; protrusion 5141; injection hole 515; protrusion 516; buckle position 517; first blocking surface 5171; second blocking surface 5172; hook-shaped portion 518; sealing member 52;

[0052] Compression spring member 6; trunk 61; slot 611; fixing portion 62; buckle section 621; slot 622; first elastic portion 63; first contact surface 631; second elastic portion 64; second contact surface 641; contact portion 642; connecting portion 643;

[0053] Main control board 7; clamping portion 71; wire hole 72; avoidance opening 73; wire 74;

[0054] Back cover 8; back plate 81; cylindrical portion 82; buckle groove 821; boss 83; sealing ring 84; nut 85; elastic washer 86; rubber sleeve 87; screw tube 88; nut 89;

[0055] Mesh cover 9. DETAILED DESCRIPTION

[0056] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may also be implemented in other embodiments without these specific details.

[0057] Example 1

[0058] See also Figure 1 The present invention constructs an ultrasonic sensor 100, which is a capacitive ultrasonic sensor, which may include at least a first planar electrode 1 and a second planar electrode 2. The first planar electrode 1 is conductive and is opposite to the second planar electrode 2. They are at least partially attached and insulated. They can form a planar capacitor and an electric field can be formed between the two.

[0059] Among them, when a pulse electric field or an alternating electric field of a certain frequency is applied to the planar capacitor, the planar capacitor may vibrate up and down to generate ultrasonic waves, and the ultrasonic waves are emitted to the side of the first planar electrode 1 away from the second planar electrode 2. Alternatively, the planar capacitor vibrates under the action of external ultrasonic waves, and the capacitance value formed between the first planar electrode 1 and the second planar electrode 2 will change with the vibration, thereby generating a detectable electrical signal, which is emitted to the side of the first planar electrode 1 away from the second planar electrode 2.

[0060] The ultrasonic sensor 100 of the present invention utilizes the first planar electrode 1 and the second planar electrode 2 to cooperate with each other to replace the piezoelectric ceramic sheet to form a planar capacitor, thereby avoiding the technical defects caused by the production technology of the piezoelectric ceramic sheet, and the manufacturing process of the first planar electrode 1 is convenient, low in cost, high in yield, and conducive to rapid manufacturing. Secondly, by using a capacitive ultrasonic transducer, the ultrasonic wave can obtain a narrower beam angle.

[0061] like Figure 1 As shown, the first planar electrode 1 is a planar structure and is circular in shape. Of course, the shape of the first planar electrode 1 can also be other shapes, which are not specifically limited here.

[0062] The first planar electrode 1 can be a metal film, which can be made by flattening and stretching a ductile metal material, such as aluminum, gold, and copper. Aluminum or gold can achieve a waterproof effect. Taking aluminum as an example, a ready-made aluminum ingot is used, and multiple rolling and stretching, multiple hot rolling and cold rolling are completed through an aluminum foil rolling machine to process aluminum foils of different thicknesses and hardnesses to meet the needs of ultrasound of different frequencies. It can be seen that the production materials are easy to purchase, the required equipment is cheap, the cost is low, and the process is simple.

[0063] The thickness of the metal film is between 1μm and 500μm. The thickness used in this embodiment is between 5μm and 16μm, and the preferred thickness is 8μm, 10μm, 12.5μm, and 15μm. It can be understood that the better the flexibility of the metal and the thinner the thickness, the better the sensitivity of the ultrasonic sensor 100. Different thicknesses can correspond to different ultrasonic frequencies. By adjusting the thickness of the metal film, ultrasonic sensors 100 with different frequencies can be produced. Ultrasonic waves of different frequencies can meet the effect of multiple ultrasonic waves working simultaneously in the same space without interfering with each other, which is similar to the effect of biological frequency conversion ultrasound of bats. For details, please refer to the data shown in Table 1, which shows the relationship between the thickness of the metal film in the range of 5μm to 100μm and the frequency of the ultrasonic wave under a 25°C environment.

[0064] Table 1

[0065]

[0066]

[0067] Of course, the first planar electrode 1 is not limited to being made of metal materials, and can also be a graphite film made of graphite material, which can also create a good acoustic effect.

[0068] See also Figure 2 The second planar electrode 2 may be a circular planar structure. Of course, its shape may also be other shapes, preferably matching the shape of the first planar electrode 1 .

[0069] The second planar electrode 2 may be a PCB (Printed Circuit Board), which has a conductive layer (not shown) on its surface facing the first planar electrode 1, and an insulating layer covering the surface of the conductive layer facing away from the second planar electrode 2, the insulating layer being used to achieve insulation between the second planar electrode 2 and the first planar electrode 1. Optionally, the PCB may be a double-layer board or a four-layer board.

[0070] The conductive layer may be copper. The insulating layer may include an insulating oil layer coated on the surface of the conductive layer and / or a silk-screen layer 22 printed on the surface of the conductive layer (see Figure 2); Preferably, the surface of the insulating layer facing the first planar electrode 1 is arranged in a concave-convex manner, for example, the surface forms a plurality of concentric circles in which the concave-convex portions are arranged at intervals.

[0071] In this embodiment, the insulating layer includes an insulating oil layer disposed on the conductive layer, and a silk-screen layer 22 printed on the insulating oil layer, which can be used to enhance the reliability of insulation, because the insulating oil layer is relatively thin, such as a green oil layer, which is easily damaged over time, resulting in insulation failure; on the other hand, the height difference between the silk-screen layer 22 and the surface of the second planar electrode 2 can be used to effectively avoid the vacuum adsorption effect between the second planar electrode 2 and the first planar electrode 1, because if the second planar electrode 2 and the first planar electrode 1 are vacuum adsorbed, it will cause excessive adhesion between the second planar electrode 2 and the first planar electrode 1, affecting the vibration effect. In this embodiment, the shape of the silk-screen layer 22 is a plurality of concentric circles arranged at intervals.

[0072] Of course, the second planar electrode 2 is not limited to being a PCB board, and it can also be a conductive metal plate, which has an insulating layer on the surface facing the first planar electrode 1. However, the PCB board is a preferred solution, which is conducive to the rapid and efficient manufacture of the second planar electrode 2 due to its mature manufacturing process, and the cost is low; at the same time, using the green oil insulating layer or the silk-screen insulating layer of the PCB board as the insulating layer of the capacitive ultrasonic sensor can greatly increase the capacitance value and improve the sensitivity.

[0073] like Figure 2 As shown, in this embodiment, the surface of the second planar electrode 2 facing away from the first planar electrode 1 may be provided with a pad 21 electrically connected to the conductive layer for connecting to an external power source. Of course, the surface of the second planar electrode 2 facing the first planar electrode 1 may also be provided.

[0074] In summary, the first planar electrode 1 and the second planar electrode 2 are firmly attached to each other, in contact with each other, but not short-circuited to each other, forming a stable planar capacitor, wherein the second planar electrode 2 is used as a positive electrode and the first planar electrode 1 is used as a negative electrode, which can be connected to the two ends of the power supply respectively; for example, the ultrasonic sensor 100 also includes a first electrode line (not shown) and a second electrode line (not shown), one end of the first electrode line can be mechanically and electrically connected to the pad 21 on the second planar electrode 2, and one end of the second electrode line can be directly / indirectly electrically connected to the first planar electrode 1. Of course, the polarity of the second planar electrode 2 and the first planar electrode 1 can be interchanged, and the interchange of polarity has no obvious effect on the actual detection effect.

[0075] Secondly, the diameters of the first planar electrode 1 and the second planar electrode 2 can be determined according to the requirements. For example, the diameters of the first planar electrode 1 and the second planar electrode 2 can be increased to make the ultrasonic sensor 100 more sensitive, because the capacitance can obtain a larger capacitance as the area of ​​the positive and negative electrodes increases. Alternatively, the diameter between the first planar electrode 1 and the second planar electrode 2 can be reduced to meet the requirements of miniaturization of the ultrasonic sensor 100.

[0076] Example 2

[0077] See also Figure 3 and Figure 4 In this embodiment, the ultrasonic sensor 100 of the present invention includes at least a housing 3, a connecting electrode 4, a pressing structure 5, a compression spring 6, a main control board 7, a back cover 8 and a mesh cover 9 in addition to the first planar electrode 1 and the second planar electrode 2 described in Embodiment 1. Of course, these components are not necessary components for the ultrasonic sensor 100 to generate ultrasonic waves, and they are applied in this embodiment as a preferred solution.

[0078] It can be understood that the outer shell 3 is used to provide an installation base for the first planar electrode 1 and the second planar electrode 2, the connecting electrode 4 is used to make the first planar electrode 1 conductive, the pressing structure 5 is used to tightly fit the connecting electrode 4 to the first planar electrode 1, the compression spring member 6 is used to firmly fit the first planar electrode 1 and the second planar electrode 2 together, the main control board 7 is at least used to provide a suitable power supply for the first planar electrode 1 and the second planar electrode 2, the back cover 8 is used to seal the open end of the outer shell 3, and the mesh cover 9 is used to protect the first planar electrode 1.

[0079] See also Figure 5 The housing 3 may be tubular, such as cylindrical, and may include a first end 31 and a second end 32 opposite to the first end 31 . The first end 31 and the second end 32 are both open, and ultrasonic waves may be emitted outward from the first end 31 .

[0080] For the convenience of description of this solution, the position closer to the first end 31 is regarded as the bottom, and the position closer to the second end 32 is regarded as the top. Of course, according to the position setting of the ultrasonic sensor 100, the position closer to the first end 31 can also be regarded as the top, and the position closer to the second end 32 can be regarded as the bottom, which is not limited here.

[0081] like Figure 5 As shown, a step 33 is provided in the housing 3 for supporting the first planar electrode 1. Optionally, the step 33 is annular and is located at the bottom of the housing 3.

[0082] A stopper 34 may be provided in the housing 3 to prevent the connection electrode 4 from rotating randomly, and effectively ensure that the connection electrode 4 is relatively fixed to the first planar electrode 1. Optionally, the stopper 34 is provided on the inner peripheral side of the housing 3 and is located at the top of the step 33.

[0083] A plurality of first clamping blocks 35 may also be provided in the housing 3, which are arranged at intervals in the circumferential direction on the inner circumferential side of the housing 3, and are used to cooperate with the pressing structure 5 so that the pressing structure 5 is pressed tightly against the connecting electrode 4. In this embodiment, four first clamping blocks 35 are provided in the housing 3, which are located above the step 33. Of course, the number of the first clamping blocks 35 can be at least one, as long as the contact area between the first clamping blocks 35 and the pressing structure 5 is sufficient to stabilize the pressing structure 5.

[0084] The housing 3 may further be provided with a plurality of second card blocks 36, which are arranged at intervals on the inner peripheral side of the housing 3, and are used to cooperate with the back cover 8 to provide a mounting base for the back cover 8 to be fixedly mounted on the top of the housing 3. The second card blocks 36 are located above the plurality of first card blocks 35, and are spaced apart from the plurality of first card blocks 35 in the longitudinal direction. In this embodiment, four second card blocks 36 are provided in the housing 3.

[0085] The top end wall of the shell 3 may also be provided with a limiting groove 37 for cooperating with the back cover 8 to prevent the back cover 8 from rotating at will, thereby effectively ensuring that the back cover 8 can be relatively fixed to the shell 3 after being installed on the shell 3.

[0086] See also Figure 6 , Figure 6 The assembly relationship between the first planar electrode 1 and the housing 3 is shown. It should be noted that for the convenience of viewing the figure, Figure 6 The structure of the housing 3 is partially omitted, and the same is true for some of the drawings mentioned below, which will not be specifically described below. The diameter of the first planar electrode 1 is larger than the inner diameter of the step 33 and smaller than the inner diameter of the housing 3 , and the first planar electrode 1 is placed flatly on the step 33 .

[0087] See also Figure 7 The connecting electrode 4 is placed on the top of the first planar electrode 1, fits with the first planar electrode 1, and is located at the periphery of the second planar electrode 2. The connecting electrode 4 also plays the role of pressing the first planar electrode 1 and the step 33 of the housing 3, so that the first planar electrode 1 and the step 33 fit together. Secondly, the assembled connecting electrode 4 is located below the plurality of first card blocks 35, and there is a longitudinal distance between the plurality of first card blocks 35.

[0088] like Figure 7As shown, the connecting electrode 4 may be annular, such as a circular ring, whose outer diameter matches the inner diameter of the housing 3, and whose inner diameter is smaller than the diameter of the first planar electrode 1. The connecting electrode 4 may be made of a conductive metal material, such as aluminum, copper, or gold. Of course, the connecting electrode 4 is not limited to being made of a conductive material, and it may also be achieved by plating a conductive coating on the outer surface of a non-conductive body. The material of the conductive coating may be aluminum, copper, gold, and the like.

[0089] The connecting electrode 4 may be provided with a plurality of through slots 41, the number of which matches the number of the first clamping block 35 and the second clamping block 36, wherein any through slot 41 is formed at the outer edge of the connecting electrode 4 through the upper and lower surfaces. Through these through slots 41, the connecting electrode 4 can smoothly pass through the first clamping block 35 and the second clamping block 36 to reach the top of the first planar electrode 1. Moreover, one of the through slots 41 can be inserted into the limit block 34 of the housing 3, so that the connecting electrode 4 and the first planar electrode 1 are relatively stationary with the housing 3, protecting the first planar electrode 1 from relative displacement during the assembly process, so as to ensure the integrity of the first planar electrode 1. Optionally, the connecting electrode 4 is provided with four through slots 41, which are located at the periphery of the connecting electrode 4.

[0090] The connecting electrode 4 may also be provided with a through-hole pad 42 for mechanically and electrically connecting to the wire 74 assembly to connect to the main control board 7. In this embodiment, the through-hole pad 42 is in the shape of a half hole and is located at the periphery of the connecting electrode 4.

[0091] See also Figure 8 The pressing structure 5 is placed on the top of the connecting electrode 4, pressing the first planar electrode 1 and the connecting electrode 4 tightly in the housing 3, and ensuring that the first planar electrode 1 and the connecting electrode 4 are firmly attached together.

[0092] like Figure 8 As shown, the compression structure 5 as a whole may be annular, such as a circular ring, whose maximum outer diameter matches the inner diameter of the housing 3 , and the inner diameter is greater than or equal to the inner diameter of the connecting electrode 4 .

[0093] Review Figure 3 The compression structure 5 may include a compression ring 51 and a sealing member 52 embedded in the bottom of the compression ring 51. Of course, the sealing member 52 is not a necessary component of the compression structure 5. It is applied in this embodiment as a preferred solution to play a sealing role, such as being used for waterproofing.

[0094] See also Fig. 9The pressure ring 51 may include a ring body 511, a plurality of avoidance grooves 512 and a plurality of inclined wedges 513 arranged on the outer periphery of the ring body 511, the ring body 511 is used to provide a basis for pressing the first planar electrode 1 and the connecting electrode 4, the avoidance grooves 512 are used to allow the ring body 511 to pass through the first clamping block 35 and the second clamping block 36 smoothly, and the inclined wedges 513 are used to cooperate with the first clamping block 35 to press the ring body 511 down below the first clamping block 35, that is, the first clamping block 35 is facing the side of the first end 31. The pressure ring 51 also leaves space on the outer periphery of the ring body 511 for the second electrode line connected to the connecting electrode 4 to extend to the main control board 7.

[0095] like Fig. 9 As shown, the ring body 511 may include a first ring segment 5111 and a second ring segment 5112 , the outer diameter of the first ring segment 5111 is smaller than the outer diameter of the second ring segment 5112 , and the first ring segment 5111 is farther away from the first planar electrode 1 than the second ring segment 5112 .

[0096] The number of the plurality of avoidance grooves 512 matches the number of the first clamping blocks 35. In this embodiment, four avoidance grooves 512 are provided. The plurality of avoidance grooves 512 can be arranged at intervals on the outer periphery of the ring body 511 in the circumferential direction. Optionally, the avoidance groove 512 can be in the shape of an arc column, and is formed by being recessed along the outer wall of the second ring segment 5112, and notches are provided at the top and bottom of the second ring segment 5112. Of course, the avoidance groove 512 is not a necessary component of the pressure ring 51. Whether the pressure ring 51 is provided with the avoidance groove 512 depends on the maximum outer diameter of the ring body 511.

[0097] The number of the plurality of inclined wedges 513 matches the number of the first clamping blocks 35. Of course, at least one inclined wedge 513 can also achieve the above effect. In this embodiment, the number of the inclined wedges 513 is four. The plurality of inclined wedges 513 can be arranged at intervals on the outer periphery of the ring body 511 in the circumferential direction. The inclined wedges 513 correspond to the avoidance grooves 512 one by one, and any inclined wedge 513 is located on the periphery of the corresponding avoidance groove 512.

[0098] The top of any inclined wedge 513 has an inclined surface 5131 and a force-bearing surface 5132, and the inclined surface 5131 serves to facilitate the force-bearing surface 5132 to rotate to the bottom of the first block 35. It is inclined in the direction of the first block 35 closest to the inclined wedge 513, wherein the lower side of the inclined surface 5131 is adjacent to the first block 35 closest to the inclined wedge 513, and the higher side of the inclined surface 5131 is connected to the force-bearing surface 5132; the force-bearing surface 5132 can be a plane, which is arranged parallel to the bottom surface of the first block 35, and the distance from the position of the force-bearing surface 5132 to the connecting electrode 4 before the downward pressure is completed is greater than or equal to the distance from the connecting electrode 4 to the bottom of the first block 35.

[0099] For example, the seal 52 may partially overflow after being embedded in the ring body 511. During the assembly process, the ring body 511 passes through the first block 35 and the second block 36 smoothly through a number of avoidance grooves 512 and is placed on the top of the connecting electrode 4. At this time, the inclined surface 5131 of the inclined wedge 513 is at least partially located below the first block 35. Subsequently, the ring body 511 is rotated to displace the inclined wedge 513 in the direction of the first block 35 that is closest to it. The inclined surface 5131 of the inclined wedge 513 first contacts the first block 35, and the ring body 511 begins to press downward. During the pressing process, the seal 52 is squeezed and deformed, shortening the distance from the force surface 5132 of the inclined wedge 513 to the connecting electrode 4. As the ring body 511 rotates, the force surface 5132 of the inclined wedge 513 finally contacts the bottom of the first block 35. The ring body 511 completes the pressing process, and the first planar electrode 1 and the connecting electrode 4 are pressed tightly. Of course, the pressing process can be achieved without the seal 52 overflowing, which depends on the difference between the distance from the position of the force-bearing surface 5132 to the connecting electrode 4 before the pressing is completed and the distance from the connecting electrode 4 to the bottom of the first block 35 .

[0100] Continue reading Fig. 9 The compression ring 51 may also include two mounting grooves 514 disposed at the top of the ring body 511, which are used to provide a mounting base for the compression spring member 6. In this embodiment, the two mounting grooves 514 are evenly and spacedly arranged in the circumferential direction of the ring body 511, wherein the number of mounting grooves 514 is not limited to two, and more than three mounting grooves 514 may be provided according to the structure of the compression spring member 6. Of course, the number of mounting grooves 514 may also be one, for example, one end of the compression spring member 6 is installed in the mounting groove 514, and the other end thereof may be tightly pressed against the inner peripheral side wall of the ring body 511.

[0101] Any mounting groove 514 can be in an arc column shape, and of course, it can also be in other shapes, as long as it is compatible with the compression spring member 6. The mounting groove 514 is formed by being recessed inward along the top of the ring body 511, and has a first notch located at the top of the ring body 511 and a second notch located at the inner side wall of the ring body 511; secondly, two inner side walls located in the circumferential direction of the compression ring 51 in the mounting groove 514 are respectively provided with protrusions 5141, which are used to cooperate with the compression spring member 6 to prevent the compression spring member 6 from loosening, and there is a distance between the protrusion 5141 and the groove bottom of the mounting groove 514 and the inner side wall of the mounting groove 514.

[0102] Continue reading Fig. 9The pressure ring 51 may also include a plurality of injection holes 515 disposed at the top of the ring body 511 for injecting glue to fill one or more gaps formed by at least two combinations of the housing 3, the pressure ring 51, the seal 52, the connecting electrode 4 and the first planar electrode 1. In this embodiment, the injection holes 515 are formed on the first ring segment 5111 and communicate with the vacant space formed on the periphery of the first ring segment 5111 and the second ring segment 5112. Optionally, the outer surface of the inclined wedge 513 protrudes from the outer surface of the second ring segment 5112 so that the glue flows to the gap.

[0103] Understandably, the mouth of the glue-filling tube filled with glue can be extended into the injection hole 515 for glue filling. The glue flows into each gap under the action of gravity. After the glue solidifies, the first planar electrode 1 can be firmly adhered. Otherwise, the first planar electrode 1 cannot withstand the fitting pressure from the second planar electrode 2 and falls off. It can also ensure that the surface of the first planar electrode 1 is basically flat. The fitting pressure given by the second planar electrode 2 is also conducive to the flatness of the surface of the planar electrode 1. If there are wrinkles on the first planar electrode 1, it will affect the generation of ultrasonic waves. In addition, the glue can further prevent the pressure ring 51 from rotating and loosening, improve reliability, and at the same time improve the waterproof performance, so that the protection effect of the entire sensor is better and the structure is stronger.

[0104] The glue can be a polyurethane potting glue with good fluidity and viscosity, and the polyurethane potting glue has high hardness after solidification. Secondly, the number of injection holes can be at least one, which can also play the above role, and when multiple holes are provided, the uniformity of the injection can be ensured. In this embodiment, four injection holes 515 are provided, which are evenly and spacedly arranged around the ring body 511.

[0105] Continue reading Fig. 9 The pressure ring 51 may also include a protrusion 516 disposed on the ring body 511 and protruding from the top of the ring body 511, and a buckle position 517 located on the side of the ring body 511 facing away from the conductor film. The protrusion 516 and the buckle position 517 are kept at a distance in the circumferential direction and can cooperate with the buckle position 517 to provide a mounting base for the main control board 7. In this embodiment, the pressure ring 51 includes two protrusions 516 and two buckles 517, wherein the two protrusions 516 and the two buckles 517 are combined in pairs and are located on opposite sides of the pressure ring 51.

[0106] The protrusion 516 may be in the shape of a square column and may extend longitudinally upward along the top of the first ring segment 5111 .

[0107] The entrance of the buckle position 517 is circumferentially oriented toward the protrusion 516 so that part of the structure of the main control board 7 can extend into it. The size of the entrance can also be larger than the size inside the buckle position 517 to facilitate the installation of the main control board 7. At the same time, the buckle position 517 has a first blocking surface 5171 that cooperates with the protrusion 516 to limit the rotation of the main control board 7, and a second blocking surface 5172 for limiting the main control board 7 from separating from the pressure ring 51 in the longitudinal direction. The plane where the second blocking surface 5172 is located is located above the top of the pressure ring 51 and is parallel to the top surface of the pressure ring 51.

[0108] Optionally, the buckle position 517 can be formed by a hook-shaped portion 518 disposed on the periphery of the ring body 511, such as Fig. 9 As shown, the hook portion 518 may be L-shaped, including a first section and a second section connected to the first section, the first section is fixedly connected to the ring body 511, the second section is located above the ring body 511, and its end away from the first section extends in the direction of the corresponding protrusion 516, and the bottom surface of the second section, the side surface of the first section and the top surface of the ring body 511 together form a buckle position 517.

[0109] In this embodiment, the avoidance grooves 512, the inclined wedges 513, the buckling positions 517, the protrusions 516, the injection holes 515, and the installation grooves 514 are arranged to avoid each other in the circumferential direction of the pressure ring 51, that is, they are not in the same longitudinal position.

[0110] Can be reviewed Figure 3 The sealing member 52 is annular and may have deformation capability, such as elastic deformation capability, and may be embedded in an annular groove formed by the inward depression at the bottom of the ring body 511. Optionally, the sealing member 52 may be a silicone ring.

[0111] See also Fig.10 The diameter of the second planar electrode 2 is smaller than or equal to the inner diameter of the pressure ring 51 . The second planar electrode 2 is installed in the central through hole of the pressure ring 51 and fits with the first planar electrode 1 .

[0112] The compression spring 6 is placed on the top of the second planar electrode 2 and fixed on the pressure ring 51 structure, so that the second planar electrode 2 and the first planar electrode 1 are firmly attached together.

[0113] See also Fig.11The compression spring member 6 may include a longitudinal main body 61, a fixing portion 62 disposed on the main body 61, and a first elastic portion 63 located on the side of the main body 61 facing the second planar electrode 2, wherein the fixing portion 62 is used to relatively fix the main body 61 on one side of the second planar electrode 2, and the first elastic portion 63 has elastic deformation capability, is used to contact the second planar electrode 2, and deform after contact, and exert downward pressure in the direction of the second planar electrode 2. Optionally, the compression spring member 6 may be made of plastic material, which has a simple structure, is easy to assemble, and has low cost, and is particularly suitable for mass production.

[0114] like Fig.11 As shown, the compression spring member 6 includes two fixing portions 62, which are respectively provided at the two ends of the main body 61, and are used to be installed in the installation groove 514 of the pressure ring 51. It can be understood that the number of the fixing portion 62 can be set to at least one, and the setting of multiple fixing portions can improve the reliability of the fixing installation of the main body 61. In some embodiments where a single fixing portion 62 is provided, the fixing portion 62 can still be provided on one end of the main body 61, and the other end of the main body 61 can be tightly against the inner peripheral side wall of the ring body 511.

[0115] Optionally, the fixing portion 62 may include two snap-on sections 621 extending outward from the end of the main body 61, the two snap-on sections 621 are spaced apart along the width direction of the main body 61 and have elastic deformation capability, each snap-on section 621 is provided with a slot 622 for cooperating with the protrusion 5141 of the mounting slot 514, the slot 622 is recessed along the top of the snap-on section 621, and has a third slot located at the top of the snap-on section 621 and a fourth slot located on the side wall of the snap-on section facing the corresponding protrusion 5141.

[0116] It is understandable that during the assembly process, a force may be applied to the fixing portion 62 to bring the two buckle segments 621 closer together, so that the fixing portion 62 Fig.10 As shown, the pressing ring 51 smoothly enters the installation groove 514 of the pressing ring 51, and then the force applied to the fixing portion 62 is released. The two buckle sections 621 return to their original positions due to the disappearance of the external force. At the same time, the protrusion 5141 in the installation groove 514 enters the groove 622 on the buckle section 621, restricting the fixing portion 62 from leaving the installation groove 514.

[0117] See also Fig.12 The first elastic part 63 has a first contact surface 631 for contacting the second planar electrode 2, and it includes a natural state and a deformed state. The natural state is that there is a distance between the first contact surface 631 and the plane where the trunk is located. The deformed state is that the first elastic part 63 is deformed, and the first contact surface 631 is displaced toward the plane where the trunk is located. The distance between the first contact surface 631 and the plane where the trunk is located is shortened, and the first elastic part 63 generates an elastic force, which is the downward pressure mentioned above, and its direction is away from the plane where the trunk 61 is located.

[0118] Alternatively, if Fig.12 As shown, the first elastic portion 63 is a longitudinal arc-shaped sheet structure, and the arc surface facing the second planar electrode 2 is the first contact surface 631. The two ends of the first elastic portion 63 are respectively combined on the main body 61, and the connecting line of the two ends is parallel / coincident with the length direction of the main body 61.

[0119] In this embodiment, the main body 61 is provided with a slot 611 at a position corresponding to the first elastic part 63 to facilitate deformation of the first elastic part 63. The slot 611 may be in a square column shape, and its length direction is parallel to / coincides with the length direction of the main body 61.

[0120] Please combine Fig.11 , Fig.12 For reference, the compression spring member 6 may further include two second elastic parts 64 located on both sides of the main body 61 and connected to the main body 61. The second elastic part 64 has elastic deformation capability, is used to contact the second planar electrode 2, and deforms after contact, and applies downward pressure in the direction of the second planar electrode 2. It can be understood that the first elastic part 63 is used to press down the middle position of the second planar electrode 2, and the second elastic part 64 is used to press down the outer position of the second planar electrode 2 located outside the middle position.

[0121] Any second elastic part 64 is provided with a second contact surface 641 for contacting the second planar electrode 2. The second elastic part 64 includes a natural state and a deformed state. The natural state is that there is a distance between the second contact surface 641 and the plane where the main trunk is located. The deformed state is that the second elastic part 64 is deformed, and the second contact surface 641 is displaced toward the plane where the main trunk is located. The distance between the second contact surface 641 and the plane where the main trunk is located is shortened, and the second elastic part 64 generates an elastic force, which is the downward pressure mentioned above, and its direction is away from the plane where the main trunk is located.

[0122] Alternatively, if Fig.11 As shown, the second elastic portion 64 may include a contact portion 642 and two connecting portions 643 combined at both ends of the contact portion 642. The contact portion 642 is used to abut the second planar electrode 2, and its surface facing the second planar electrode 2 is the second contact surface 641. The contact portion 642 is located below the plane where the main body 61 is located in a natural state. In this embodiment, the contact portion 642 is arc-shaped to avoid the pad 21 provided on the second planar electrode 2. The connecting portion 643 is used to connect the contact portion 642 and the main body 61 / fixing portion 62. The connecting portion 643 can meander downward from the main body 61 / fixing portion 62 and gradually extend in the direction of the connecting portion 643.

[0123] It should be noted that the number of the connecting portion 643 can be at least one. In an embodiment where one connecting portion 643 is provided, one end of the connecting portion 643 may be fixedly connected to the middle of the main body 61 , and the other end thereof may be connected to the contact portion 642 .

[0124] See also Fig.13 The main control board 7 is installed on the top of the pressing ring 51 and is relatively fixed to the pressing ring 51.

[0125] The main control board 7 can be connected to the second planar electrode 2 through the first electrode line, and connected to the connecting electrode 4 through the second electrode line to control the capacitance formed between the second planar electrode 2 and the first planar electrode 1. The main control board 7 is also provided with a plurality of circuit components (not shown) on the surface facing away from the second planar electrode 2. These circuit components are used to form a boost circuit, a signal amplification and processing circuit, a communication circuit, a main control chip, etc. It should be noted that the method for controlling the capacitance of the main control board 7, as well as the construction of the boost circuit, the signal amplification and processing circuit, the communication circuit, and the main control chip can refer to the prior art, and will not be repeated here.

[0126] like Fig.13 As shown, the main control board 7 may include a plurality of clip portions 71 located at its outer peripheral edge and arranged circumferentially at intervals. The clip portions 71 are at least partially used to cooperate with the pressure ring 51 to fixedly mount the entire main control board 7 on the pressure ring 51. At the same time, the intervals between the clip portions 71 enable the main control board 7 to smoothly pass through the first clamping block 35 and the second clamping block 36.

[0127] The clamping portion 71 may be an arc-shaped sheet structure, and the length of the clamping portion 71 in the circumferential direction is adapted to the distance between the first blocking surface 5171 of the buckle 517 and the protrusion 516 in the circumferential direction. For example, the distance between the first blocking surface 5171 and the protrusion 516 in the circumferential direction is slightly greater than or equal to the length of the clamping portion 71 in the circumferential direction.

[0128] It can be understood that during assembly, the main control board 7 can be tilted into the outer shell 3, and one side of the tilted clamping portion 71 can smoothly enter the buckle position 517 of the pressure ring 51. Since part of the structure of the clamping portion 71 enters the buckle position 517, the other side of the clamping portion 71 can also successfully enter the installation position formed between the buckle position 517 and the protrusion 516.

[0129] Continue reading Fig.13 The main control board 7 may also be provided with a plurality of wire holes 72 for passing wires 74 connected to the main control board 7 .

[0130] The main control board 7 may also be provided with an escape opening 73 for allowing the first electrode line connected to the second planar electrode 2 to pass through.

[0131] See also Fig.14The back cover 8 is installed on the second end 32 of the shell 3 and blocks the second end 32 of the shell 3. The installation method can be interference fit, screw connection, clamping connection, etc.

[0132] like Fig.14 As shown, the back cover 8 may include a back plate 81 and a cylindrical portion 82 arranged on the back plate 81. The outer surface of the cylindrical portion 82 is provided with a plurality of buckle grooves 821 for cooperating with the second block 36 in the outer shell 3 to fixedly install the back cover 8 in the outer shell 3.

[0133] The buckle slot 821 may be L-shaped, and may include a fifth slot for the second block 36 to enter, and a slot interior located on one side of the fifth slot in the circumferential direction of the cylindrical portion 82, connected to the fifth slot, and used to limit the second block 36 from being separated from the slot. It can be understood that before the back cover 8 is installed, the position of the fifth slot is aligned with the position of the second block 36, and then the back cover 8 can be smoothly installed in the housing 3, and the second block 36 can be relatively moved to the interior of the slot by rotating.

[0134] Continue reading Fig.14 The back plate 81 is used to connect to the cylindrical portion 82 and is provided with a boss 83 at its surface edge. After the back cover 8 is installed in the shell 3, the boss 83 can enter the limiting groove 37 of the shell 3 to prevent the back cover 8 from rotating and loosening, and ensure that it is assembled in place.

[0135] The outer circumference of the cylindrical portion 82 may be sleeved with one or more sealing rings 84 for sealing, such as waterproofing.

[0136] Please read back Figure 3 , Figure 4 The ultrasonic sensor 100 further includes a mounting accessory for fixing the wire 74 connected to the main control board 7. In this embodiment, the mounting accessory may include a nut 85, an elastic washer 86, a rubber sleeve 87, a screw 88, and a nut 89. It can be understood that the nut 89, the elastic washer 86, the rubber sleeve 87, the screw 88, the nut 85, and the wire 74 are arranged in accordance with the embodiment of the present invention. Figure 3 The positions are arranged as shown, the elastic washer 86 is sleeved on the lower end of the screw tube 88, the rubber sleeve 87 is sleeved into the screw tube 88, the nut 85 is lightly screwed, the assembled screw tube 88 is installed on the top of the back cover 8, and its lower end passes through the back cover 8 and is fixed to the back cover 8 with the nut 89. The wire 74 passes through the screw tube 88 and is welded to the main control board 7. Of course, the end of the wire 74 can also be provided with a plug, which is directly inserted into the socket on the main control board 7 to facilitate connection with the main control board 7.

[0137] Continue reading Figure 4The mesh cover 9 is installed at the first end 31 of the housing 3, and the installation method can be interference fit, screw connection, clamping connection, etc. The mesh cover 9 is provided with a plurality of mesh holes for facilitating ultrasonic emission. It can be understood that the mesh cover 9 is applied to the present embodiment as a preferred solution, and the mesh cover 9 may be selected not to be installed in other embodiments.

[0138] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A capacitive ultrasonic sensor, characterized in that: It comprises a first planar electrode (1) and a second planar electrode (2) which are arranged opposite to each other; The first planar electrode (1) and the second planar electrode (2) are at least partially attached and insulated to form a stable planar capacitor; Wherein, the first planar electrode (1) is a conductive film.

2. The capacitive ultrasonic sensor according to claim 1, characterized in that: The conductive film includes a metal film or a graphite film.

3. The capacitive ultrasonic sensor according to claim 1, characterized in that: The thickness of the conductive film is 1 μm-500 μm.

4. The capacitive ultrasonic sensor according to claim 1, characterized in that: The second planar electrode (2) comprises a conductive metal plate, and an insulating layer is provided on the side of the metal plate facing the first planar electrode (1).

5. The capacitive ultrasonic sensor according to claim 1, characterized in that: The second planar electrode (2) comprises a PCB board, wherein the PCB board is provided with a conductive layer located on a side facing the first planar electrode (1), and a solder pad electrically connected to the conductive layer.

6. The capacitive ultrasonic sensor according to claim 5, characterized in that: An insulating layer is provided on the surface of the conductive layer facing the first planar electrode (1).

7. The capacitive ultrasonic sensor according to claim 6, characterized in that: The insulating layer comprises an insulating oil layer and / or a silk-screen layer (22) arranged on the surface of the conductive layer.

8. The capacitive ultrasonic sensor according to claim 7, characterized in that: The surface of the insulating layer facing the first planar electrode (1) is arranged in a concavo-convex manner.

9. The capacitive ultrasonic sensor according to any one of claims 1 to 8, characterized in that: The capacitive ultrasonic sensor comprises a cylindrical housing (3) in which a step (33) is provided, and the first planar electrode (1) is placed on the step (33).

10. The capacitive ultrasonic sensor according to claim 9, characterized in that: The capacitive ultrasonic sensor comprises a connecting electrode (4); The connecting electrode (4) is a planar structure and is electrically connected to the first planar electrode (1). The connecting electrode (4) is located at the periphery of the second planar electrode (2) and is attached to a surface of the first planar electrode (1) that is opposite to the step (33).

11. The capacitive ultrasonic sensor according to claim 10, characterized in that: The capacitive ultrasonic sensor comprises a pressure ring (51) which abuts against a surface of the connecting electrode (4) facing away from the first planar electrode (1), and the periphery of the pressure ring (51) is clamped on the inner circumference of the housing (3) to press the connecting electrode (4) and the first planar electrode (1) onto the step (33).

12. The capacitive ultrasonic sensor according to claim 11, characterized in that: The capacitive ultrasonic sensor comprises a sealing member (52) embedded in a surface of one side of the pressure ring (51) facing the connecting electrode (4).

13. The capacitive ultrasonic sensor according to claim 12, characterized in that: The pressure ring is provided with a liquid injection hole (515) for injecting glue, and the glue is solidified and formed in one or more gaps formed by at least two combinations of the housing (3), the pressure ring (51), the sealing member (52), the connecting electrode (4) and the first planar electrode (1).

14. The capacitive ultrasonic sensor according to claim 9, characterized in that: The capacitive ultrasonic sensor comprises a compression spring member (6) which is relatively fixed to a side of the second planar electrode (2) facing away from the first planar electrode (1) and abuts against the second planar electrode (2) to apply a force to the second planar electrode (2) so as to be in close contact with the first planar electrode (1).

15. The capacitive ultrasonic sensor according to claim 11, characterized in that: The capacitive ultrasonic sensor further comprises a main control board (7), which is mounted on a side of the pressure ring (51) facing away from the connecting electrode (4) and is electrically connected to the second planar electrode (2) and the connecting electrode (4).

16. The capacitive ultrasonic sensor according to claim 9, characterized in that: The capacitive ultrasonic sensor further comprises a mesh cover (9) mounted on an end of the housing (3) close to the first planar electrode (1).

17. The capacitive ultrasonic sensor according to claim 9, characterized in that: The capacitive ultrasonic sensor further comprises a back cover (8) which is mounted on an end of the housing (3) away from the first planar electrode (1) and blocks an opening of the end of the housing (3) away from the first planar electrode (1).

18. The capacitive ultrasonic sensor according to claim 17, characterized in that: A second clamping block (36) is provided on the inner circumference of the housing (3); A buckle slot (821) is provided on the outer periphery of the back cover (8), wherein the buckle slot (821) has a notch and an interior of a slot communicating with the notch and located on one side of the notch in the circumferential direction of the back cover (8); The back cover (8) is inserted into the outer shell (3), and the second clamping block (36) is relatively moved into the groove by rotation to prevent the back cover (8) from being separated from the outer shell (3).

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