A split piezoelectric sensor

Abstract

The present invention discloses a split piezoelectric sensor, which relates to the field of piezoelectric sensing, and includes a first circuit board and a second circuit board; the first circuit board includes a split board, a piezoelectric film and a first connector; the split board and the first circuit board are located in the same plane, the split board is located in the hollow area of ​​the first circuit board and is connected to one end in the first circuit board, so that the split board is displaced with one end in the first circuit board as a fulcrum; the piezoelectric film is attached to the split board and is electrically connected to the split board; the first connector is arranged on the same side as the piezoelectric film, and the first connector is electrically connected to the first circuit board; the second circuit board includes a signal processing unit and a second connector electrically connected to the signal processing unit; the second connector is opposite to the first connector and is detachably connected, and the second connector supports the first circuit board. The technical effect of the present invention is that the piezoelectric film and the operation processing unit are separated, and the piezoelectric film can be disassembled and tested at any time, thereby realizing the reuse of the piezoelectric film circuit board.

Description

Technical Field

[0001] The invention relates to the field of piezoelectric sensing, and in particular to a split piezoelectric sensor. Background Art

[0002] Piezoelectric film is a new type of high molecular polymer flexible transducer material, which can be processed into efficient, reliable and low-cost vibration sensors or accelerometers, and can also be combined with appropriate circuits to form wireless detection and monitoring systems. Due to the many advantages of piezoelectric film sensors, they have been widely used in many fields such as construction, speed and acceleration measurement, medical physiological signal collection, and vehicle anti-theft.

[0003] Currently, most piezoelectric film sensors are cantilever type, with the piezoelectric film attached to the inner side of the cantilever. When the sensor is subjected to external longitudinal stress, it will generate greater stress in the lateral direction, resulting in deformation and electrical signals. After conversion by the signal processing unit, specific measurement parameters are obtained.

[0004] There are generally two types of cantilever structures for existing piezoelectric film sensors: one is an integrated type, in which a cantilever structure is directly hollowed out by slotting on a circuit board with signal processing, and then the piezoelectric film is attached to the side of the cantilever with an electrode (generally the inside). However, the piezoelectric film after attachment is easily affected by the heat of the circuit board because it is on the same circuit board as the signal processing unit. The piezoelectric film after attachment cannot be tested separately and is difficult to repair. If the piezoelectric film is damaged, the sensor can only be replaced as a whole, which is costly.

[0005] The other is welding or riveting, which uses metal plates or ceramic plates as suspension beams, and then installs the metal plates or ceramic plates with piezoelectric films on the bottom plate with signal processing units by welding or riveting. The riveted or welded ends have both the functions of connection and signal transmission. However, since piezoelectric films are polymer materials and are not resistant to high temperatures, they may be damaged or their performance may degrade during the welding process, and the pasting quality of the films is not easy to detect. In addition, welding or riveting is not conducive to the disassembly of the sensor, especially the riveting method, which can only be disassembled destructively, which is not conducive to maintenance and reuse of piezoelectric film plates. Summary of the invention

[0006] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a split piezoelectric sensor that can flexibly replace and test the performance of the piezoelectric film.

[0007] To achieve the above object, the present invention provides a split piezoelectric sensor, comprising a first circuit board and a second circuit board;

[0008] The first circuit board includes a sub-board, a piezoelectric film and a first connector; the sub-board and the first circuit board are located in the same plane, the sub-board is located in the hollow area of ​​the first circuit board and is connected to one end in the first circuit board, so that the sub-board is displaced with one end in the first circuit board as a fulcrum; the piezoelectric film is attached to the sub-board and is electrically connected to the sub-board; the first connector is arranged on the same side as the piezoelectric film, and the first connector is electrically connected to the first circuit board;

[0009] The second circuit board includes a signal processing unit and a second connector electrically connected to the signal processing unit; the second connector is opposite to and detachably connected to the first connector, and the second connector supports the first circuit board.

[0010] Furthermore, the second circuit board is provided with copper cladding on a surface of one side of the second connector.

[0011] Furthermore, there are a plurality of the first connectors and the second connectors, and the first connectors surround the hollow area.

[0012] Furthermore, it also includes: an elastic pad, which is arranged between the piezoelectric film and the second circuit board.

[0013] Furthermore, a shielding cover is disposed on a surface of the first circuit board opposite to the piezoelectric film, and the shielding cover surrounds the hollow area.

[0014] Furthermore, the shielding cover includes a through hole.

[0015] The technical effect of the present invention is that the piezoelectric film and the operation processing unit are separated, and the piezoelectric film can be disassembled at any time and is easy to test, thereby realizing the reuse of the piezoelectric film circuit board.

[0016] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0018] Figure 1 A bottom view of the structure of the first circuit board of the present invention;

[0019] Figure 2 is a schematic structural diagram of a second circuit board of the present invention;

[0020] Figure 3 A top view of the structure of the first circuit board of the present invention;

[0021] Figure 4 It is a structural stereogram of the first circuit board of the present invention.

[0022] Explanation of reference numerals: 100 - first circuit board; 101 - piezoelectric film; 102 - first connector; 103 - sub-board; 104 - metal shielding cover welding point; 105 - metal shielding cover; 106 - through hole; 200 - second circuit board; 201 - second connector; 202 - elastic pad. DETAILED DESCRIPTION

[0023] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0024] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0025] Figure 1 The figure shows the inner structure of the first circuit board 100. The first circuit board 100 is hollowed out, and the sub-board 103 is located in the hollowed-out area inside the first circuit board 100, and is connected to one end inside the first circuit board 100 and is located in the same plane. The sub-board 103 is also covered with a piezoelectric film 101 electrically connected thereto, and a first connector 102 is also provided on the same side of the piezoelectric film 191.

[0026] The split board 103 can use one end connected to the first circuit board 100 as a fulcrum, generate bending deformation according to the direction of the compressive stress when subjected to compressive stress, and generate cyclical displacement due to elasticity when the compressive stress is released.

[0027] The material of the piezoelectric film 101 can be a common piezoelectric material, such as polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS), etc., which is not limited here. When the sub-plate 103 is deformed by compressive stress, the piezoelectric film 101 will be deformed together, generating an electrical signal, and the electrical signal generated by the piezoelectric film 101 is transmitted to the first connector 102 arranged on the same side as the piezoelectric film 101 through the circuit on the first circuit board 100.

[0028] Of course, in order to generate cyclic displacement, the end of the split board 103 is not connected to the circuit board. In addition, a portion of space needs to be reserved between the first circuit board 100 and the second circuit board 200 to provide enough space for the displacement of the split board 103 .

[0029] Figure 2 The schematic diagram of the structure of the second circuit board 200 is shown, which is provided with a second connector 201 and an elastic pad 202. In addition, the second circuit board 200 is also integrated with a signal processing unit (not shown in the figure).

[0030] The second connector 201 is arranged opposite to the first connector 102 and is detachably connected. The second connector 201 receives the electrical signal transmitted from the first connector 102 and transmits it to the signal processing unit. The signal processing unit responds to the electrical signal and processes it to obtain the detection result. When the sensor is working, the second connector 201 supports the first circuit board 100, so that it deforms as a support when the sub-board 103 is subjected to compressive stress, so that the piezoelectric film 101 generates a sufficient amount of detectable electrical signals.

[0031] In order to make the support of the first circuit board 100 more stable, there may be more than two first connectors 102 and second connectors opposite thereto, and they are arranged around the hollow area outside the split board 103 .

[0032] In this embodiment, the first connector 102 and the second connector 201 are plug-in board connectors with a certain height. When the first circuit board 100 and the second circuit board 200 are connected, a certain gap is formed between the two, and the distance between the boards is nominally 0.98 mm.

[0033] The elastic pad 202 is arranged in the aforementioned gap and should be in contact with the sub-plate 103 and the piezoelectric film 101, so as to alleviate the vibration interference caused by the overall movement of the external sensor, and can also support the sub-plate 103 and the piezoelectric film 101, and help to generate pre-pressure. In this embodiment, the elastic pad 202 uses soft silicone with a thickness of 1 mm. The thickness of the soft silicone will also vary according to the height of the inter-board connector. The hardness of the soft silicone can be selected from 20 to 40 Shore hardness, which can be adjusted according to the compressive stress to be measured. In addition, the elastic pad 202 can also press the piezoelectric film 101 to prevent it from accidentally falling off.

[0034] Furthermore, a surface of the second circuit board 200 close to the first circuit board 100 is copper-clad for grounding and shielding environmental electromagnetic noise.

[0035] Figure 3 , Figure 4 The outer structure of the first circuit board 100 is shown. A metal shielding cover 105 is provided outside the hollow area. The metal shielding cover 105 surrounds the sub-board 103 to suppress environmental electromagnetic noise and avoid power frequency electromagnetic interference. The metal shielding cover 105 is generally an alloy of zinc, copper and nickel.

[0036] The metal shield 105 has a through hole 106. When the sensor is in use, the bump of the external device to be tested can pass through the through hole to generate compressive stress on the first circuit board. The position of the through hole can be selected at any position of the sub-board 103, and the sub-board 103 only needs to produce corresponding deformation when subjected to compressive stress. It can also be adjusted according to the size range of the compressive stress to be measured. For example, when the compressive stress to be measured is small, the through hole can be arranged at the end of the sub-board 103, and the sensor is more sensitive; relatively, when the compressive stress to be measured is large, the through hole can also be arranged in the middle of the sub-board 103 or toward the connecting end of the sub-board 103.

[0037] In one embodiment, when the sensor is working, the piezoelectric film 101 is sandwiched between two shielding layers, with the metal shielding cover 105 shielding the upper side and the copper-clad shielding of the second circuit board 200 shielding the lower side, which together suppress environmental interference.

[0038] Furthermore, the first circuit board 100 and the second circuit board 200 both use conventional circuit board material FR-4 (epoxy resin glass fiber laminate), and other circuit board materials that can be designed with circuits may also be used, such as a composite substrate single-sided half-fiberglass board 22F, a single-sided fiberglass board CEM-1, and a double-sided half-fiberglass board CEM-3 or a metal substrate.

[0039] When manufacturing the sensor, firstly, the inter-board connector and the metal shielding cover 105 are welded on the first circuit board 100 and the second circuit board 200, respectively. Then, the piezoelectric film 101 is pasted at room temperature and the first circuit board 100 and the second circuit board 200 are tested respectively. After the test is completed, the first circuit board 100 is directly plugged into the second circuit board 200 to form a complete piezoelectric sensor. When repairing, the first circuit board 100 can be directly removed to test the fault separately, and the piezoelectric film 101 can be easily replaced, and high-temperature operation is avoided in the presence of the piezoelectric film, thereby preventing the damage of the piezoelectric film caused by high temperature.

[0040] Furthermore, the elastic pad 202 may not be provided in the gap between the first circuit board 100 and the second circuit board 200, and the sensor can be used as an acceleration sensor. When the sensor is vibrated, since there is no elastic pad 202, the sub-board 103 also vibrates, driving the piezoelectric film 101 to deform. At this time, by providing a signal processing unit, the current acceleration value can be accurately obtained.

[0041] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A split piezoelectric sensor, characterized in that: comprising a first circuit board and a second circuit board; The first circuit board includes a sub-board, a piezoelectric film and a first connector; the sub-board and the first circuit board are located in the same plane, the sub-board is located in the hollow area of ​​the first circuit board and is connected to one end in the first circuit board, so that the sub-board is displaced with one end in the first circuit board as a fulcrum; the piezoelectric film is attached to the sub-board and is electrically connected to the sub-board; the first connector is arranged on the same side as the piezoelectric film, and the first connector is electrically connected to the first circuit board; The second circuit board includes a signal processing unit and a second connector electrically connected to the signal processing unit; the second connector is opposite to and detachably connected to the first connector, the second connector supports the first circuit board, and the second connector receives the electrical signal transmitted from the first connector and transmits it to the signal processing unit.

2. The split piezoelectric sensor according to claim 1, characterized in that: The surface of the second circuit board at a side where the second connector is arranged is copper-clad.

3. The split-type piezoelectric sensor according to claim 1, characterized in that: There are a plurality of the first connectors and the second connectors, and the first connectors surround the hollow area.

4. The split-type piezoelectric sensor according to claim 1, characterized in that: Also includes: An elastic pad is disposed between the piezoelectric film and the second circuit board.

5. The split piezoelectric sensor according to any one of claims 1 to 4, characterized in that: A shielding cover is disposed on a surface of the first circuit board opposite to the piezoelectric film, and the shielding cover surrounds the hollow area.

6. The split-type piezoelectric sensor according to claim 5, characterized in that: The shielding cover includes a through hole.

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