Pyroelectric infrared sensor

Abstract

The utility model belongs to the technical field of sensors, and particularly relates to a pyroelectric infrared sensor, which mainly comprises a base with a mounting position; the first shell is provided with a mounting cavity, the first shell is arranged on the base, the mounting cavity is sealed by the base, a light-transmitting window is formed in the first shell, and the outside is communicated with the mounting cavity through the light-transmitting window; the circuit board assembly is arranged in the mounting cavity of the first shell, and the circuit board assembly is fixed relative to the base; the optical filter is arranged at the light-transmitting window of the first shell, the optical filter is matched with the light-transmitting window, a fixing layer is arranged between the optical filter and the first shell, the optical filter is fixed at the light-transmitting window of the first shell through the fixing layer, and the fixing layer and the optical filter seal the light-transmitting window. By adopting the above structure, fixation of the optical filter is facilitated, and a gap between the optical filter and the first shell can be filled, so that the mounting cavity is sealed, and the circuit board assembly in the first shell is ensured not to be affected by external factors.

Description

Technical Field

[0001] This utility model belongs to the field of sensor technology, and specifically refers to a pyroelectric infrared sensor. Background Technology

[0002] Pyroelectric infrared sensors can detect changes in infrared heat radiated by the human body in a non-contact manner and convert them into a voltage signal output. This voltage signal, after conditioning, can drive various control circuits, such as power supply switching control, burglar alarms, fire alarms, and automatic detection. Pyroelectric infrared sensors are not only suitable for burglar alarm applications but also for automatic alarms in locations with high-voltage electricity, X-rays, gamma rays, and other sources that pose significant health risks.

[0003] Pyroelectric infrared sensors are a type of sensor with great application potential. They can detect infrared radiation emitted by humans or certain animals and convert it into an electrical signal output. As early as 1028, the use of the pyroelectric effect to detect infrared radiation was proposed, but it did not receive much attention. It wasn't until the 1960s, with the rapid development of laser and infrared technologies, that research on the pyroelectric effect and the application development of pyroelectric crystals were revived. In recent years, with the rapid development of integrated circuit technology and in-depth research into the characteristics of this sensor, related application-specific integrated circuit (ASIC) processing technology has also improved rapidly.

[0004] In existing pyroelectric infrared sensors, the filter is typically assembled and fixed by covering the light-transmitting hole with a large filter and using mechanical snap-fit ​​methods. A certain gap is left between the filter and the first housing, which prevents the formation of a closed environment inside the first housing. This makes the pyroelectric infrared sensor susceptible to external influences, such as interference from external light sources, mechanical vibration, and 50Hz power frequency, thus increasing the risk of misjudgment by the pyroelectric infrared sensor. Utility Model Content

[0005] This invention provides a pyroelectric infrared sensor that solves the gap problem between the filter and the first housing in the background, thereby achieving a complete isolation and sealed environment by sealing the light-transmitting port of the first housing with the filter.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A pyroelectric infrared sensor, comprising:

[0008] The base has mounting positions;

[0009] The first housing has an installation cavity, the first housing is disposed on the base, and the base seals the installation cavity of the first housing. The first housing is provided with a light-transmitting window, which communicates the outside world with the installation cavity.

[0010] A circuit board assembly is disposed within the mounting cavity of the first housing, and the circuit board assembly is fixed relative to the base;

[0011] A filter is disposed at the light-transmitting window of the first housing. The filter is adapted to the light-transmitting window. A fixing layer is provided between the filter and the first housing. The filter is fixed to the light-transmitting window of the first housing through the fixing layer, and the fixing layer and the filter seal the light-transmitting window.

[0012] In some embodiments, the base is provided with a first pin, a second pin, and a third pin, one end of the first pin, one end of the second pin, and one end of the third pin all extend into the mounting cavity of the first housing, and the first pin, the second pin, and the third pin are all fixedly connected to the circuit board assembly; the first pin and the second pin are power input terminals, and the third pin is a signal output terminal.

[0013] In some embodiments, the base is provided with a first positioning protrusion, the first housing is provided with a matching first opening, and a welding layer is provided between the first housing and the base, the welding layer sealing the contact between the base and the first housing.

[0014] In some embodiments, a first positioning structure is provided between the base and the first housing. The first positioning structure includes a first boss disposed on the first housing and a second boss disposed on the base. When the first boss and the second boss are in corresponding positions, the base and the first housing can be welded to form the weld layer.

[0015] In some embodiments, the circuit board assembly includes a PCB board, a field-effect transistor (FET), and a positive and a negative wafer. The PCB board is electrically connected to a first pin, a second pin, and a third pin. The FET, the positive wafer, and the negative wafer are disposed on the PCB board. The positive and negative wafers are connected to the FET, and the FET is connected to the third pin.

[0016] In some embodiments, the fixing layer is a gel structure made of a mixture of graphene and conductive carbon black material, such that the gel structure is black.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0018] This application provides a fixing layer between the filter and the first housing, thereby fixing the filter to the first housing without any gap between them. The fixing layer is made of a gel structure containing graphene and conductive carbon black materials, thus forming a good electromagnetic shielding structure. The fixing layer is black and has a good light absorption structure. By adopting the above structure, the interior of the first housing is a sealed environment, reducing the influence of external factors on the pyroelectric infrared sensor.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0020] Figure 1 This is an exploded view of a pyroelectric infrared sensor according to the present invention.

[0021] Figure 2 This is a three-dimensional structural diagram of the first housing of this utility model;

[0022] Figure 3 This is a perspective view of a pyroelectric infrared sensor according to the present invention;

[0023] Figure 4 This is a cross-sectional view of the assembly of the first housing and the filter of this utility model. Detailed Implementation

[0024] The present application will be further described in detail below with reference to the accompanying drawings. In the description of the embodiments, unless otherwise stated, the terms "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the present application must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present application.

[0025] like Figure 1-4As shown, this utility model provides a pyroelectric infrared sensor, mainly comprising a base 103, a first housing 101, a circuit board assembly 1032, and a filter 102. The base 103 has a mounting position for mounting the first housing 101; the first housing 101 has a mounting cavity, and the first housing 101 is disposed on the base 103, which seals the mounting cavity, thus forming a sealed working space; a light-transmitting window 1011 is provided on one side of the first housing 101, connecting the outside world to the mounting cavity. A filter 102 is disposed at the light-transmitting window 1011, completely covering the window to prevent light from entering the mounting cavity without passing through the filter 102 and affecting the pyroelectric infrared sensor. The circuit board assembly 1032 is disposed in the mounting cavity of the first housing 101 and is fixed relative to the base. It should be noted that a fixing layer 1014 is provided at the edge of the light-transmitting window 1011. The filter 102 is fixed to the inner wall of the first housing 101 through the fixing layer 1014. Compared with the traditional filter 102 fixing mode, by setting the fixing layer 1014, the edge gap between the filter 102 and the inner wall of the first housing 101 can be filled. Thus, combined with the base 103, the mounting cavity of the first housing 101 is formed into a sealed working environment, achieving better electromagnetic shielding and avoiding light interference. This perfectly solves the problem that pyroelectric infrared sensors are susceptible to external interference.

[0026] In this embodiment, both the first housing 101 and the base 103 are metal structures, which can effectively achieve electromagnetic shielding. Meanwhile, the fixing layer 1014 uses an adhesive containing graphene and conductive carbon black. The black adhesive effectively prevents light from entering the mounting cavity of the first housing 101. The adhesive has a viscosity of 3000-6000 cps, and its flowability allows for one-time molding, filling the entire bonding bottom. The black adhesive material has good light-blocking and heat-absorbing properties, while the conductive carbon black and graphene have excellent thermal conductivity and electromagnetic shielding properties, thus achieving a mounting cavity that provides both light isolation and electromagnetic shielding.

[0027] In one embodiment, a first pin 1034, a second pin 1036, and a third pin 1035 are provided on the base 103. All three pins are fixed relative to the base 103. The first pin 1034 and the second pin 1036 are power input terminals, and the third pin 1035 is a signal output terminal. One end of the first pin 1034, one end of the second pin 1036, and one end of the third pin 1035 extend into the mounting cavity of the first housing 101 and connect to the circuit board assembly 1032.

[0028] In one embodiment, to facilitate the assembly between the first housing 101 and the base 103, a first positioning protrusion 1031 is provided on the base 103, and a first opening 1013 is provided on the first housing 101. The size of the first opening 1013 matches the size of the first positioning protrusion 1031. In this embodiment, the first positioning protrusion 1031 is a circular boss, and the first opening 1013 is a circular opening. The inner diameter of the first opening 1013 matches the outer diameter of the first positioning protrusion 1031, thereby providing positioning support when the first housing 101 is fixed relative to the base 103. When the first housing 101 is fixed to the base via the first positioning protrusion 1031 and the first opening 1013, welding is performed at the contact line between the first housing 101 and the base 103 to form a weld layer. The weld layer fixes the position between the first housing 101 and the base 103. At the same time, the weld layer also ensures the seal at the connection between the first housing 101 and the base 103, ensuring that the mounting cavity of the first housing 101 is a sealed environment.

[0029] Furthermore, to facilitate the relative positioning of the first housing 101 and the base 103 before welding, and to ensure that the relative positions of the first housing 101 and the base 103 are correct, a first positioning structure is provided between the first housing 101 and the base 103. The first positioning structure includes a first boss 1012 provided on the first housing 101 and a second boss 1033 provided on the base 103. When the first boss 1012 and the second boss 1033 are in corresponding positions, the base 103 and the first housing 101 can be welded to form a welding layer, thereby ensuring that the first housing 101 is in the correct position relative to the base 103, which facilitates assembly, and during welding, the circuit board assembly 1032 located on the base 103 can be clearly positioned in the correct position relative to the first housing 101.

[0030] In one embodiment, the circuit board assembly 1032 includes a PCB board, a high-resistance transistor, a field-effect transistor (FET), and a positive and a negative chip. The PCB board is electrically connected to the first pin 1034, the second pin 1036, and the third pin 1035. The FET, the positive chip, and the negative chip are disposed on the PCB board. The positive and negative chips are connected to the FET through the high-resistance transistor, forming an amplifier circuit. The FET is connected to the third pin 1035. The signal input through the positive and negative chips is amplified by the FET and then output to the outside through the third pin 1035.

[0031] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model. These improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A pyroelectric infrared sensor, characterized by include: The base has mounting positions; The first housing has an installation cavity, the first housing is disposed on the base, and the base seals the installation cavity of the first housing. The first housing is provided with a light-transmitting window, which communicates the outside world with the installation cavity. A circuit board assembly is disposed within the mounting cavity of the first housing, and the circuit board assembly is fixed relative to the base; A filter is disposed at the light-transmitting window of the first housing. The filter is adapted to the light-transmitting window. A fixing layer is provided between the filter and the first housing. The filter is fixed to the light-transmitting window of the first housing through the fixing layer, and the fixing layer and the filter seal the light-transmitting window.

2. A pyroelectric infrared sensor according to claim 1, characterized in that The base is provided with a first pin, a second pin, and a third pin. One end of the first pin, one end of the second pin, and one end of the third pin all extend into the mounting cavity of the first housing, and the first pin, the second pin, and the third pin are all fixedly connected to the circuit board assembly. The first pin and the second pin are power input terminals, and the third pin is a signal output terminal.

3. A pyroelectric infrared sensor according to claim 1, wherein The base is provided with a first positioning protrusion, the first housing is provided with a matching first opening, and a welding layer is provided between the first housing and the base, the welding layer sealing the contact between the base and the first housing.

4. A pyroelectric infrared sensor according to claim 3, characterized in that A first positioning structure is provided between the base and the first housing. The first positioning structure includes a first boss disposed on the first housing and a second boss disposed on the base. When the first boss and the second boss are in corresponding positions, the base and the first housing can be welded to form the weld layer.

5. A pyroelectric infrared sensor according to claim 2, characterized in that, The circuit board assembly includes a PCB board, a field-effect transistor (FET), a positive chip, and a negative chip. The PCB board is electrically connected to the first pin, the second pin, and the third pin. The FET, the positive chip, and the negative chip are disposed on the PCB board. The positive chip and the negative chip are connected to the FET, and the FET is connected to the third pin.

6. A pyroelectric infrared sensor according to claim 1, wherein The fixing layer is a black gel structure.

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