Passive infrared sensor

Abstract

This invention provides a passive infrared sensor, which includes an amplification circuit. This amplification circuit, based on range matching, avoids the need for an additional bias voltage. This simplifies the circuit structure and optimizes the long power-on time caused by the low high-pass cutoff frequency. Furthermore, based on a corresponding DC-DC removal design, it reduces or even eliminates the delay caused by DC-DC removal, thus improving the real-time response of the passive infrared sensor to human activity. This results in a better user experience in the practical application of the passive infrared sensor.

Description

Technical Field

[0001] This utility model relates to the field of infrared detection, and more specifically to a passive infrared sensor. Background Technology

[0002] With the development of IoT technology and the popularization of low-carbon and environmentally friendly concepts, artificial intelligence, smart homes, and smart security technologies are increasingly demanding environmental detection, especially human movement detection. This allows for intelligent control of electrical equipment based on the detection of human presence, such as controlling lighting fixtures to achieve intelligent, low-carbon lighting. Passive infrared detection technology is a relatively mature human presence detection technology. Its detection principle is based on a multi-window lens partitioning a corresponding detection area, using a pyroelectric infrared sensor (PIR) to detect cross-zone movements of a person within that area. Passive infrared detection technology combines low cost with the ability to precisely set the detection angle based on the multi-window lens structure design, and it does not infringe on human privacy, thus becoming the most widely used human presence detection technology currently. Regarding the detection signal output by the pyroelectric infrared sensor, those skilled in the art generally believe that the frequency components of the effective signal corresponding to human cross-zone movement in the detection signal are concentrated in the range of 0.3Hz to 10Hz, and the energy proportion of the effective signal below 0.3Hz is extremely low, and its intensity decreases with the increase of detection distance. Correspondingly, when the high-pass cutoff frequency of the corresponding infrared sensor's amplifier circuit is set to a frequency below 0.3Hz, it will not increase the energy proportion of the effective signal, and the low high-pass cutoff frequency of the amplifier circuit will cause the problem of excessively long power-on time.

[0003] Furthermore, the detection signal output by the pyroelectric infrared sensor also contains a DC component. This DC component does not carry change information associated with the detected target, and its presence can easily mask lower-intensity signals in the analysis and processing of information corresponding to the effective signal, especially when the effective signal contains frequency components below 0.3 Hz. Therefore, amplification and DC removal processes are essential for the analysis and processing of information corresponding to the effective signal. However, existing DC removal methods are not suitable for retaining frequency components below 0.3 Hz in the effective signal. Specifically, existing DC removal methods mainly employ high-pass algorithms, differential DC removal, or capacitance-based DC removal. High-pass and differential DC removal rely on the cumulative recording of historical data, which increases hardware costs and exacerbates latency issues if the goal is to retain frequency components below 0.3 Hz in the effective signal. In other words, regarding the removal of DC bias from the probe signal under the requirements of extracting and analyzing the effective signal, both high-pass and differential DC removal methods inherently involve a certain time delay. Furthermore, when using a high-pass cutoff frequency below 0.3Hz to remove DC bias in order to retain frequency components below 0.3Hz in the effective signal, it increases hardware costs and exacerbates the time delay problem. Capacitor DC blocking utilizes the DC blocking characteristic of capacitors to remove DC bias from the probe signal; however, for capacitors with a cutoff frequency below 0.3Hz, excessive capacitance can lead to significant time delay, severe signal attenuation, or unstable transmission.

[0004] Therefore, in the existing design of infrared sensors, on the one hand, based on the experience of those skilled in the art regarding the frequency components of the effective signal corresponding to human cross-zone movement in the detection signal, it is believed that the energy of the actual effective signal is concentrated in the range of 0.3Hz to 10Hz. On the other hand, under the requirements of extracting and analyzing the information corresponding to the effective signal, for the amplification and DC removal of the detection signal, using a frequency lower than 0.3Hz as the high-pass cutoff frequency would exacerbate the problems of excessive power-on time and delay in existing amplification circuits and DC removal methods. Therefore, infrared sensors using existing amplification circuits and DC removal methods generally use a frequency greater than or equal to 0.3Hz as the minimum cutoff frequency to extract the effective signal from the detection signal. Utility Model Content

[0005] One objective of this invention is to provide a passive infrared sensor, wherein the passive infrared sensor has an amplification circuit. The amplification circuit, based on range matching, can avoid the application of an additional bias voltage. This simplifies the circuit structure of the amplification circuit and helps to optimize the problem of excessive power-on time caused by the low high-pass cutoff frequency. Therefore, it is beneficial to obtain a good user experience in the practical application of the passive infrared sensor.

[0006] One objective of this invention is to provide a passive infrared sensor, wherein the passive infrared sensor, based on the circuit structure design of the amplifier circuit, is further based on a corresponding DC removal design. For the DC removal processing required for the extraction and analysis of information corresponding to the effective signal, the DC removal processing can reduce or even avoid the time delay caused by the DC removal processing, thereby improving the real-time response of the passive infrared sensor to human activities. Therefore, it is beneficial to obtain a good user experience in the practical application of the passive infrared sensor.

[0007] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit is based on a corresponding DC-DC de-energization design to maintain its low latency advantage while further preserving the frequency components below 0.3Hz in the effective signal. Thus, in long-distance detection applications, the passive infrared sensor is suitable for detecting long-distance human cross-zone movements by incorporating the slowly varying signal below 0.3Hz in the detection signal into the effective signal.

[0008] Another objective of this invention is to provide a passive infrared sensor, wherein the amplifier circuit is based on a corresponding DC-DC removal design, which has a low dependence on computing and memory resources for the purpose of DC removal, and thus can maintain its low latency advantage at a low hardware cost.

[0009] Another objective of this invention is to provide a passive infrared sensor, wherein the DC-DC removal process of the amplifier circuit based on the corresponding DC-DC removal design differs from existing DC-DC removal methods and does not damage the integrity of the effective signal, thus helping to ensure the detection accuracy and reliability of the passive infrared sensor.

[0010] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit has at least two operational amplifier stages. Each operational amplifier stage is configured as a negative feedback AC amplification circuit powered by a single power supply. Each operational amplifier stage has its output terminal connected to its inverting input terminal via a feedback resistor, and its inverting input terminal connected to one end of a series RC circuit. At least one operational amplifier is further configured as a circuit that also functions as a DC amplification circuit and is designated as a first operational amplifier. The inverting input terminal of the first operational amplifier is further connected to the other end of the series RC circuit connected to its inverting input terminal via a resistor equivalent circuit. At least one operational amplifier stage has its non-inverting input terminal connected to the first operational amplifier. The output of the amplifier is used as the subsequent operational amplifier of the first operational amplifier. This allows the non-inverting input of the subsequent operational amplifier to have a raised DC bias, avoiding the need for additional bias voltage for range matching purposes. This simplifies the circuit structure of the amplifier circuit. Furthermore, by reducing the initial voltage difference requirement between the non-inverting and inverting inputs of the first operational amplifier, the voltages of the non-inverting and inverting inputs of the first operational amplifier can be made closer at the beginning of power-up of the passive infrared sensor. Consequently, the output of the first operational amplifier can quickly stabilize. This also helps to optimize the problem of excessively long power-up time caused by the low high-pass cutoff frequency of the amplifier circuit.

[0011] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit, based on a corresponding DC removal design, samples the non-inverting input and output of the final operational amplifier via a DC path, and performs DC removal processing on the two sampled digital signals by synchronous subtraction or cancellation. Thus, it can dynamically remove the DC component from the signal output by the amplification circuit in real time, thereby reducing or even avoiding the time delay caused by DC removal processing and improving the real-time response of the passive infrared sensor to human activity.

[0012] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit performs DC removal processing on the two digital signals obtained by direct sampling using a synchronous subtraction or cancellation operation. Therefore, the operation is simple and the synchronous subtraction or cancellation operation can avoid the cumulative recording of historical data, thus avoiding time delay and having a low dependence on computing and memory resources.

[0013] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit performs DC removal processing on the two digital signals acquired by direct sampling by synchronous subtraction or cancellation. The frequency components of the effective signal retained by the amplification circuit are associated with the high-pass cutoff frequency of the amplification circuit, and the frequency components below 0.3Hz in the effective signal can be retained based on the high-pass cutoff frequency of the amplification circuit.

[0014] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit performs DC removal processing on the two digital signals acquired by direct sampling using a synchronous subtraction or cancellation operation. Therefore, the DC removal process of the amplification circuit will not destroy the integrity of the effective signal, thereby ensuring the detection accuracy and reliability of the passive infrared sensor.

[0015] Another objective of this invention is to provide a passive infrared sensor, wherein the amplification circuit samples the non-inverting input and output of the final operational amplifier via a DC path. The non-inverting input and output of the final operational amplifier are respectively connected to different ADC ports via DC paths. Thus, with at least two amplification stages in the amplification circuit, the high impedance of the non-inverting input of the final operational amplifier and its low impedance output ensure that the two ADC ports connected for sampling have low impedance inputs. This allows for rapid charging of the sampling capacitor within the ADC, ensuring that the target voltage value is reached within a limited sampling time. This avoids conversion errors caused by quantization before voltage stability due to charging delay. Simultaneously, the low impedance input accelerates charge discharge to reduce inter-channel crosstalk.

[0016] Another objective of this invention is to provide a passive infrared sensor, wherein the non-inverting input and output of the final operational amplifier of the amplifier circuit are respectively connected to different ADC ports via DC paths. In this way, with at least two amplification stages in the amplifier circuit, the high-impedance non-inverting input of the final operational amplifier has the characteristic of low-impedance input, avoiding unexpected parameter changes in the amplifier circuit caused by sampling the non-inverting input of the final operational amplifier via DC paths. Therefore, it is beneficial to ensure the detection accuracy and reliability of the passive infrared sensor.

[0017] To achieve at least one of the above objectives, this utility model provides a passive infrared sensor, the passive infrared sensor comprising:

[0018] A pyroelectric infrared sensor; and

[0019] An amplifier circuit is provided, which amplifies the signal output by the pyroelectric infrared sensor and has at least two operational amplifier stages. Each operational amplifier stage is configured as a negative feedback AC amplifier circuit powered by a single power supply. Each operational amplifier stage is connected to its inverting input via a feedback resistor at its output terminal and to one end of a series RC circuit at its inverting input terminal. At least one operational amplifier is further configured as a circuit that also has DC amplification function and is named a first operational amplifier. The inverting input terminal of the first operational amplifier is further connected to the other end of the series RC circuit connected to its inverting input terminal via a resistor equivalent circuit. At least one operational amplifier stage is connected to the output terminal of the first operational amplifier at its non-inverting input terminal as a subsequent operational amplifier stage. The subsequent operational amplifier stage is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply and grounded to the AC signal via a series RC circuit at its inverting input terminal.

[0020] In one embodiment, the first operational amplifier is configured as a single-supply non-inverting negative feedback AC amplifier circuit with the signal to be amplified connected at the non-inverting input and the AC signal grounded at the inverting input via a series RC circuit.

[0021] In one embodiment, the first operational amplifier is configured as an inverting negative feedback AC amplifier circuit powered by a single power supply, with the signal to be amplified connected to the inverting input via a series RC circuit, and a corresponding bias voltage connected to the non-inverting input.

[0022] In one embodiment, the amplifier circuit has two operational amplifiers, with the first operational amplifier being the primary operational amplifier of the amplifier circuit and the subsequent operational amplifier being the final operational amplifier of the amplifier circuit.

[0023] In one embodiment, the amplification circuit further includes a microcontroller having at least two ADC ports. The output and non-inverting input of the final operational amplifier of the amplification circuit are respectively connected to different ADC ports of the microcontroller via DC paths, so that the microcontroller samples the output and non-inverting input of the final operational amplifier of the amplification circuit using different ADC ports.

[0024] In one embodiment, the number of operational amplifiers in the amplifier circuit is at least three.

[0025] In one embodiment, the first operational amplifier is the primary operational amplifier of the amplifier circuit. Corresponding to the state in which the first operational amplifier is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply, the first operational amplifier is connected to the signal output by the pyroelectric infrared sensor at its non-inverting input terminal. And in the state in which the first operational amplifier is configured as an inverting negative feedback AC amplifier circuit powered by a single power supply, the first operational amplifier is connected to the signal output by the pyroelectric infrared sensor at its inverting input terminal via a series RC circuit.

[0026] In one embodiment, each operational amplifier stage after the first operational amplifier is configured as a non-inverting negative feedback AC amplifier circuit with its non-inverting input connected to the output of the preceding operational amplifier.

[0027] In one embodiment, the amplification circuit further includes a microcontroller having at least two ADC ports. The non-inverting input of one of the operational amplifiers following the first operational amplifier and the output of the final operational amplifier of the amplification circuit are respectively connected to different ADC ports of the microcontroller via DC paths. The microcontroller samples the non-inverting input of one of the operational amplifiers following the first operational amplifier and the output of the final operational amplifier of the amplification circuit using different ADC ports.

[0028] In one embodiment, the microcontroller samples the non-inverting input and output of the final operational amplifier of the amplifier circuit through different ADC ports, and the non-inverting input and output of the final operational amplifier of the amplifier circuit are respectively connected to different ADC ports of the microcontroller via DC paths.

[0029] In one embodiment, the amplification circuit further includes a microcontroller having at least two ADC ports. The microcontroller samples the non-inverting input and output of the final operational amplifier of the amplification circuit through different ADC ports. The non-inverting input and output of the final operational amplifier of the amplification circuit are respectively connected to different ADC ports of the microcontroller via DC paths.

[0030] In one embodiment, the final operational amplifier of the amplifier circuit is configured as an inverting negative feedback AC amplifier circuit powered by a single power supply. The inverting input terminal of the final operational amplifier is connected to the output terminal of the preceding operational amplifier via a series RC circuit, and a corresponding bias voltage is connected to its non-inverting input terminal.

[0031] In one embodiment, the final operational amplifier of the amplifier circuit is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply. The non-inverting input terminal of the final operational amplifier of the amplifier circuit is connected to the output terminal of the preceding operational amplifier, and the AC signal is grounded at the inverting input terminal via a series RC circuit.

[0032] This utility model also provides a passive infrared sensor, which includes:

[0033] A pyroelectric infrared sensor; and

[0034] An amplifier circuit is provided, which amplifies the signal output by the pyroelectric infrared sensor and has at least two operational amplifier stages and a microcontroller. Each operational amplifier stage is configured as a negative feedback AC amplifier circuit powered by a single power supply. The output of each operational amplifier stage is connected to its inverting input stage via a feedback resistor, and its inverting input stage is connected to one end of a series RC circuit. The microcontroller has at least two ADC ports. The non-inverting input of one of the operational amplifier stages and the output of the final operational amplifier stage are respectively connected to different ADC ports of the microcontroller via DC paths. The microcontroller samples the non-inverting input of one of the operational amplifier stages and the output of the final operational amplifier stage using different ADC ports. The operational amplifiers after the operational amplifier whose non-inverting input is connected to the ADC port of the microcontroller via a DC path are all configured as non-inverting negative feedback AC amplifier circuits powered by a single power supply, and their non-inverting inputs are connected to the output of the preceding operational amplifier stage.

[0035] The further objectives and advantages of this invention will become fully apparent from the following description and accompanying drawings. Attached Figure Description

[0036] Figure 1A This is a schematic diagram of the circuit structure of a passive infrared sensor according to an embodiment of the present invention.

[0037] Figure 1B This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0038] Figure 2A This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0039] Figure 2B This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0040] Figure 3AThis is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0041] Figure 3B This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0042] Figure 4A This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0043] Figure 4B This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0044] Figure 4C This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0045] Figure 4D This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0046] Figure 5A This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0047] Figure 5B This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0048] Figure 6 This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0049] Figure 7 This is a schematic diagram of the circuit structure of a passive infrared sensor according to another embodiment of the present invention.

[0050] Figure 8A This is a partial circuit diagram of a passive infrared sensor according to another embodiment of the present invention.

[0051] Figure 8B This is a partial circuit diagram of a passive infrared sensor according to another embodiment of the present invention.

[0052] Figure 9A This is a schematic diagram of a DC path with high-frequency filtering.

[0053] Figure 9B This is a schematic diagram of another DC path with high-frequency filtering.

[0054] Figure 9C This is a schematic diagram of a DC follower that does not amplify AC current as the DC path. Detailed Implementation

[0055] The following description is intended to disclose the present invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the present invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0056] Those skilled in the art should understand that, in the disclosure of this utility model, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this utility model.

[0057] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0058] This invention provides a passive infrared sensor, wherein the amplification circuit, based on range matching, can avoid the application of an additional bias voltage. This simplifies the circuit structure of the amplification circuit and helps to optimize the problem of excessive power-on time caused by the low high-pass cutoff frequency. Therefore, it is beneficial to obtain a good user experience in the practical application of the passive infrared sensor.

[0059] Example, referring to the accompanying drawings of the specification of this utility model. Figure 1A and Figure 1BAs shown, the circuit structure principle of a passive infrared sensor according to different embodiments of the present invention is illustrated. The passive infrared sensor includes a pyroelectric infrared sensor (PIR) 10 and an amplifier circuit 20 for amplifying the signal output by the pyroelectric infrared sensor 10. The amplifier circuit 20 has at least two amplification stages and at least two operational amplifiers 21. Each operational amplifier 21 is configured as a negative feedback AC amplifier circuit powered by a single power supply. Each operational amplifier 21 has its output terminal connected to its inverting input terminal via a feedback resistor 211, and its inverting input terminal connected to one end of a series RC circuit 212. At least one operational amplifier 21 is further configured as a circuit with DC amplification function and is designated as a first operational amplifier 21A. The inverting input terminal of the first operational amplifier 21A is further connected directly to the circuit connected to its inverting input terminal via a resistor equivalent circuit. At the other end of the series RC circuit 212A, at least one operational amplifier 21 is connected to the output of the first operational amplifier 21A at its non-inverting input terminal, thus serving as the subsequent operational amplifier of the first operational amplifier 21A. This allows the non-inverting input terminal of the subsequent operational amplifier of the first operational amplifier 21A to have a raised DC bias, avoiding the need for additional bias voltage for range matching purposes. This simplifies the circuit structure of the amplifier circuit 20. Furthermore, by reducing the initial voltage difference requirement between the non-inverting and inverting input terminals of the first operational amplifier 21A, the voltages at the non-inverting and inverting input terminals of the first operational amplifier 21A can be made closer at the initial power-on of the passive infrared sensor. Consequently, the output of the first operational amplifier 21A can quickly stabilize. This also helps to optimize the problem of excessively long power-on time caused by the low high-pass cutoff frequency of the amplifier circuit 20.

[0060] That is to say, when the amplifier circuit 20 is as Figure 1A and Figure 1B When the amplifier circuit 20 is configured to have two amplification stages, and the number of operational amplifiers 21 corresponding to the amplifier circuit 20 is two, the first operational amplifier 21A is the primary operational amplifier of the amplifier circuit 20, the subsequent operational amplifier of the first operational amplifier 21A is the final operational amplifier of the amplifier circuit 20, and is configured to use a single-supply non-inverting negative feedback AC amplifier circuit with the output terminal of the first operational amplifier 21A connected at the non-inverting input terminal and the AC signal grounded at the inverting input terminal via a series RC circuit 212.

[0061] It is understood that when the amplifier circuit 20 is configured to have more than two amplification stages and at least three operational amplifiers 21, the first operational amplifier 21A is only required to be the operational amplifier 21 before the final operational amplifier of the amplifier circuit 20. That is, the first operational amplifier 21A is not limited to the primary operational amplifier of the amplifier circuit 20, and the subsequent operational amplifier 21B of the first operational amplifier 21A is not limited to the final operational amplifier of the amplifier circuit 20.

[0062] Preferably, such as Figure 2A and Figure 2B As shown, when the amplifier circuit 20 is configured to have more than two amplification stages and at least three operational amplifiers 21, the first operational amplifier 21A is the primary operational amplifier of the amplifier circuit 20, and each operational amplifier 21 after the operational amplifier 21B following the first operational amplifier 21A is configured to have its non-inverting input connected to the output of the preceding operational amplifier 21. This ensures that each operational amplifier 21 after the operational amplifier 21B following the first operational amplifier 21A has a boosted DC bias at its non-inverting input, avoiding the need for additional bias voltage for range matching purposes, thereby simplifying the circuit structure of the amplifier circuit 20.

[0063] That is, when the amplifier circuit 20 is configured to have more than two amplification stages and has at least three operational amplifiers 21, the first operational amplifier 21A preferably corresponds to Figure 2A and Figure 2B The first operational amplifier 21A is the primary operational amplifier of the amplifier circuit 20, and each stage of the operational amplifier 21 after the first operational amplifier 21A is configured as a single-supply non-inverting negative feedback AC amplifier circuit with the non-inverting input terminal connected to the output terminal of the previous operational amplifier, and the AC signal grounded at the inverting input terminal through the series RC circuit 212.

[0064] Furthermore, in the above embodiments of this utility model, the first operational amplifier 21A can correspond to Figure 1A and Figure 2A The non-inverting negative feedback AC amplifier circuit is configured to use a single power supply, with the signal to be amplified connected to its non-inverting input and the AC signal grounded at its inverting input via the series RC circuit 212A; it can also correspond to... Figure 1B and Figure 2B The inverting negative feedback AC amplifier circuit is configured to be powered by a single power supply, with the signal to be amplified connected to its inverting input via the series RC circuit 212A, and a corresponding bias voltage connected to its non-inverting input.

[0065] Corresponding to the first operational amplifier 21A, such as Figures 1A to 2B When the primary operational amplifier of the amplifier circuit 20 is shown, the first operational amplifier 21A, when configured as a single-supply in-phase negative feedback AC amplifier circuit, connects the signal output by the pyroelectric infrared sensor 10 to its non-inverting input terminal; and when configured as a single-supply in-phase negative feedback AC amplifier circuit, connects the signal output by the pyroelectric infrared sensor 10 to its inverting input terminal via the series RC circuit 212A.

[0066] Furthermore, the amplifier circuit 20 of the passive infrared sensor can optionally be based on a corresponding DC-DC de-energization design, such as... Figures 3A to 5B The diagram further includes a microcontroller (MCU) 22, wherein the microcontroller 22 has at least two ADC ports, wherein the operational amplifier 21 after the first operational amplifier 21A is as follows: Figures 3A to 4D The circuits shown are all configured as single-supply, non-inverting negative feedback AC amplifier circuits. The non-inverting input of one of the operational amplifiers 21 after the first operational amplifier 21A and the output of the final operational amplifier of the amplifier circuit 20 are respectively connected to different ADC ports of the microcontroller 22 via DC paths. The microcontroller 22 samples the non-inverting input of one of the operational amplifiers 21 after the first operational amplifier 21A and the output of the final operational amplifier of the amplifier circuit 20 through different ADC ports. It is suitable for performing DC removal processing on the two sampled digital signals by synchronous subtraction or cancellation. In this way, the DC component in the signal amplified and output by the amplifier circuit 20 is removed in real time, thereby avoiding the time delay caused by DC removal processing and improving the real-time response of the passive infrared sensor to human activity.

[0067] It is worth mentioning that the aforementioned advantages of the DC-DC de-amplification design of the passive infrared sensor's amplifier circuit 20 do not rely on the design of the first operational amplifier 21A also having DC amplification functionality. Therefore, in these embodiments of the present invention, the DC-DC de-amplification design of the passive infrared sensor's amplifier circuit 20 allows it to exist independently of the design of the first operational amplifier 21A having DC amplification functionality. This corresponds to the design of the passive infrared sensor's amplifier circuit 20 in the present invention. Figures 3A to 7 In some embodiments, the resistor connected in parallel with the capacitor of the series RC circuit 212A of the first operational amplifier 21A or the resistor connected in parallel with the series RC circuit 212A as a whole can be removed, and this invention does not limit this.

[0068] In other words, in some embodiments of this utility model, the passive infrared sensor includes the pyroelectric infrared sensor 10 and the amplification circuit 20. The amplification circuit 20 amplifies the signal output by the pyroelectric infrared sensor 10 and has at least two operational amplifier stages 21 and the microcontroller 22. Each operational amplifier stage 21 is configured as a negative feedback AC amplifier circuit powered by a single power supply. Each operational amplifier stage 21 has its output terminal connected to its inverting input terminal via a feedback resistor 211, and its inverting input terminal connected to one end of a series RC circuit 212. The microcontroller 22 has at least two analog-to-digital converters (ADCs). Port C: The non-inverting input of one of the operational amplifiers 21 in the amplifier circuit 20 and the output of the final operational amplifier are respectively connected to different ADC ports of the microcontroller 22 via DC paths. The microcontroller 22 samples the non-inverting input of one of the operational amplifiers 21 in the amplifier circuit 20 and the output of the final operational amplifier via different ADC ports. All operational amplifiers 21 after the operational amplifier 21 connected to the ADC port of the microcontroller 22 via DC paths at the non-inverting input are configured as non-inverting negative feedback AC amplifier circuits powered by a single power supply, and the output of the preceding operational amplifier is connected to the non-inverting input.

[0069] It is understood that all operational amplifiers 21 after the first operational amplifier 21A are configured as non-inverting negative feedback AC amplifier circuits powered by a single power supply. When the operating state of the final stage operational amplifier of the amplifier circuit 20 is established and a relatively stable amplification factor is achieved, the non-inverting input terminal of any operational amplifier 21 after the first operational amplifier 21A has the same DC bias voltage as the output terminal of the final stage operational amplifier of the amplifier circuit 20. This allows for the connection between the non-inverting input terminal of one of the operational amplifiers 21 after the first operational amplifier 21A and the output terminal of the final stage operational amplifier of the amplifier circuit 20. After the output terminals of the operational amplifiers are connected to different ADC ports of the microcontroller 22 via DC paths, the microcontroller 22 can sample the non-inverting input terminal of one of the operational amplifiers 21 after the first operational amplifier 21A and the output terminal of the final stage operational amplifier of the amplifier circuit 20. The two sampled digital signals are processed by synchronous subtraction or cancellation to remove DC components, thereby removing the DC components from the signal amplified and output by the amplifier circuit 20 in real time. This avoids the time delay caused by the DC removal process and improves the real-time response of the passive infrared sensor to human activity.

[0070] In other words, the amplifier circuit 20 performs DC removal processing on the two digital signals obtained by direct sampling using a synchronous subtraction or cancellation operation. Therefore, the operation is simple and the synchronous subtraction or cancellation operation can avoid the cumulative recording of historical data, thus avoiding time delay and having a low dependence on computing and memory resources. This allows it to maintain its low-latency advantage with a low hardware cost. Unlike existing DC removal methods, it does not destroy the integrity of the effective signal, which is beneficial to ensuring the detection accuracy and reliability of the passive infrared sensor.

[0071] Furthermore, the frequency components of the effective signal retained by the amplifier circuit 20 are related to the high-pass cutoff frequency of the amplifier circuit 20. Based on the high-pass cutoff frequency of the amplifier circuit, the amplifier circuit 20 can retain frequency components below 0.3Hz in the effective signal. That is, the amplifier circuit 20 is suitable for maintaining its low latency advantage while further retaining frequency components below 0.3Hz in the effective signal. Corresponding to the application scenario of long-distance detection, the passive infrared sensor is suitable for detecting long-distance human cross-area movements by incorporating the slowly varying signal below 0.3Hz in the detection signal into the effective signal, taking advantage of the characteristic that human cross-area movements can generate slowly varying signals below 0.3Hz in the detection signal.

[0072] Specifically, the microcontroller 22 preferably samples the output of the final operational amplifier in the amplifier circuit 20 and the non-inverting input of the operational amplifier 21 preceding the final operational amplifier, respectively. Figures 3A to 4B as well as Figure 5A and Figure 5B As shown, different ADC ports are used to sample the signals at the non-inverting input and output of the final operational amplifier of the amplifier circuit 20. The non-inverting input and output of the final operational amplifier of the amplifier circuit 20 are connected to different ADC ports of the microcontroller 22 via DC paths. This utilizes the characteristic that the DC bias at the output of the final operational amplifier of the amplifier circuit 20 and the DC bias at the non-inverting input have the same magnitude and tend to synchronize with each other, resulting in better synchronization. This ensures the synchronization of the DC bias in the two sampled signals. Correspondingly, when performing DC removal processing on the two sampled digital signals using synchronous subtraction or cancellation, the DC component in the amplified output signal of the amplifier circuit 20 can be removed accurately and in real time. This avoids the time delay caused by DC removal processing, thus improving the real-time response of the passive infrared sensor to human activity, while ensuring the detection accuracy and reliability of the passive infrared sensor.

[0073] Furthermore, compared to sampling at the output of the final operational amplifier of the amplifier circuit 20 and the non-inverting input of the operational amplifier 21 before the final operational amplifier, sampling at the non-inverting input and output of the final operational amplifier of the amplifier circuit 20 can ensure the strength of the two sampled signals and thus the sampling accuracy of the ADC under the inherent detection accuracy limitations of the ADC. Correspondingly, when the two sampled digital signals are processed by synchronous subtraction or cancellation to remove DC, weak signals in the signal after DC removal can be effectively preserved and the correlation between the weak signals and the detection target can be ensured. This ensures the detection accuracy of the passive infrared sensor for weak signals and improves the detection accuracy and reliability of the passive infrared sensor.

[0074] Specifically, in Figure 3A and Figure 3B In the circuit structure of the passive infrared sensor shown, the amplifier circuit 20 has two operational amplifiers 21. Therefore, the operational amplifier 21 after the first operational amplifier 21A is the final operational amplifier of the amplifier circuit 20. The structure in which the microcontroller 22 samples the non-inverting input terminal of one of the operational amplifiers 21 after the first operational amplifier 21A and the output terminal of the final operational amplifier of the amplifier circuit 20 through different ADC ports is equivalent to the structure in which the microcontroller 22 samples the non-inverting input terminal and the output terminal of the final operational amplifier of the amplifier circuit 20 through different ADC ports.

[0075] exist Figures 4A to 4D In the circuit structure of the passive infrared sensor shown, the amplification circuit 20 of the passive infrared sensor is configured to have at least three operational amplifiers 21 with more than two amplification stages. The microcontroller 22 samples the non-inverting input of one of the operational amplifiers 21 after the first operational amplifier 21A and the output of the final operational amplifier of the amplification circuit 20 through different ADC ports, and preferably corresponds to... Figure 4A and Figure 4B The amplifier circuit 20 samples the data at the non-inverting input and output terminals of the final operational amplifier using different ADC ports.

[0076] It is worth mentioning that when the passive infrared sensor's amplifier circuit 20 is configured to have more than two amplification stages and at least three operational amplifiers 21, and when the microcontroller 22 is configured to sample the non-inverting input and output of the final operational amplifier of the amplifier circuit 20 using different ADC ports, the final operational amplifier of the amplifier circuit 20 is not limited to being configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply.

[0077] In other words, in some embodiments of this utility model, when the passive infrared sensor's amplification circuit 20 is configured to have more than two amplification stages and at least three operational amplifiers 21, and when the microcontroller 22 is configured to sample the non-inverting input and output of the final operational amplifier of the amplification circuit 20 using different ADC ports, the final operational amplifier of the amplification circuit 20 can also correspond to... Figure 5A and Figure 5B The inverting negative feedback AC amplifier circuit is configured to use a single power supply. The final stage operational amplifier of the amplifier circuit 20 is connected to the output of the preceding operational amplifier via a series RC circuit 212 at its inverting input terminal and to a corresponding bias voltage at its non-inverting input terminal.

[0078] It is worth mentioning that the ADC port exhibits low impedance characteristics based on the internal working principle of the ADC. Compared to sampling at the output of the final operational amplifier of the amplifier circuit 20 and the output of the pyroelectric infrared sensor 10, the sampling method in the above embodiments of this utility model enables the two ADC ports connected for the purpose of sampling to have low impedance input, thereby avoiding impedance mismatch problems. This avoids unexpected parameter changes in the amplifier circuit 20 and avoids modulation effects on the original signal output by the pyroelectric infrared sensor 10, thus helping to ensure the detection accuracy and reliability of the passive infrared sensor.

[0079] Those skilled in the art will understand that, in the circuit structure of the passive infrared sensor described in the above embodiments of the present invention, the operational amplifiers 21 at each stage are further adapted to be combined with conventional improvements to enhance the relevant performance of the amplifier circuit 22, for example, corresponding to Figure 6 As shown in Figure 3A Based on the circuit structure of the passive infrared sensor shown, capacitors are connected between the non-inverting and inverting input terminals of each operational amplifier 21 to enhance the anti-interference performance of the amplifier circuit 20, and / or capacitors are connected in parallel with the feedback resistors 211 of each operational amplifier 21 to prevent self-oscillation of the operational amplifier 21 and filter high-frequency interference to ensure the stability of the amplifier circuit 20, and / or the signal to be amplified is connected to the non-inverting input terminal of each operational amplifier 21 through a resistor and grounded through a capacitor to form a corresponding filter circuit to ensure the anti-interference performance of the amplifier circuit 20, and / or the primary operational amplifier of the amplifier circuit 20 is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply, corresponding to Figure 7The inverting input terminal of the primary operational amplifier of the amplifier circuit 20 is connected to the AC signal ground via a series RC circuit 212, while a DC bias voltage is connected. This allows the voltages at the non-inverting and inverting input terminals of the primary operational amplifier of the amplifier circuit 20 to approach each other at the beginning of power-on of the passive infrared sensor, enabling the output of the primary operational amplifier to stabilize quickly. This further shortens the power-on time of the amplifier circuit 20, thereby solving the problem of excessively long power-on time caused by the low high-pass cutoff frequency of the amplifier circuit 20. This invention does not limit this aspect.

[0080] It is worth mentioning that, in the above embodiments of this utility model, the first operational amplifier 21A of the amplifier circuit 20 is further connected to the other end of the series RC circuit 212A connected to its inverting input terminal via a resistor equivalent circuit, thus also having a DC amplification function. This corresponds to the state where the first operational amplifier 21A is configured as a single-supply in-phase negative feedback AC amplifier circuit, where the first operational amplifier 21A is grounded to the AC signal via the series RC circuit 212A at its inverting input terminal and simultaneously connected to ground via the resistor equivalent circuit; and the state where the first operational amplifier 21A is configured as a single-supply in-phase negative feedback AC amplifier circuit, where the first operational amplifier 21A is connected to the signal to be amplified via the series RC circuit 212A at its inverting input terminal and simultaneously connected to the signal to be amplified via the resistor equivalent circuit. Here, the resistor equivalent circuit is a circuit that is equivalent to a resistor for DC, and the resistor equivalent circuit can correspond to... Figures 1A to 6 The state where 8A has a resistor connected in parallel with the capacitor in the series RC circuit 212A is equivalently formed by the resistor in the series RC circuit 212A and the resistor connected in parallel with the capacitor in the series RC circuit 212A; it can also correspond to Figure 7 and Figure 8B In the case where a resistor is connected in parallel with the entire series RC circuit 212A, the circuit is equivalent to the resistor connected in parallel with the entire series RC circuit 212A, and this utility model does not limit this.

[0081] Furthermore, those skilled in the art should understand that in the description of this utility model, a DC path refers to a line or circuit that allows DC current to pass through, and does not constitute a limitation on whether AC components can pass through. For example, in Figure 6 and Figure 7In the circuit structure of the passive infrared sensor shown, the signal to be amplified is connected to the non-inverting input of the final operational amplifier of the amplifier circuit 20 via a resistor and grounded via a capacitor to form a corresponding filter circuit. The sampling point of the microcontroller 22 at the non-inverting input of the final operational amplifier of the amplifier circuit 20 can be at either end of the resistor in the filter circuit. The corresponding connection method can form a DC path between the non-inverting input of the final operational amplifier of the amplifier circuit 20 and the corresponding ADC port of the microcontroller 22. This invention is not limited in this respect; the corresponding DC path can be a path directly connected by a wire, a path with a resistor, or... Figure 9A and Figure 9B The DC path with high-frequency filtering shown can also be... Figure 9C The illustrated follower that passes DC without amplifying AC, or a circuit that allows DC to pass through, formed by a combination of at least two of the above DC paths.

[0082] It will be understood by those skilled in the art that the above embodiments are merely examples, and features of different embodiments can be combined with each other to obtain implementation methods that are readily conceived of according to the content disclosed in this utility model but are not explicitly shown in the accompanying drawings.

[0083] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments. Without departing from the stated principles, the implementation of the present invention may have any variations or modifications.

Claims

1. A passive infrared sensor, characterized in that include: A pyroelectric infrared sensor; and An amplifier circuit is provided, which amplifies the signal output by the pyroelectric infrared sensor and has at least two operational amplifier stages. Each operational amplifier stage is configured as a negative feedback AC amplifier circuit powered by a single power supply. Each operational amplifier stage is connected to its inverting input via a feedback resistor at its output terminal and to one end of a series RC circuit at its inverting input terminal. At least one operational amplifier is further configured as a circuit that also has DC amplification function and is named a first operational amplifier. The inverting input terminal of the first operational amplifier is further connected to the other end of the series RC circuit connected to its inverting input terminal via a resistor equivalent circuit. At least one operational amplifier stage is connected to the output terminal of the first operational amplifier at its non-inverting input terminal as a subsequent operational amplifier stage. The subsequent operational amplifier stage is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply and grounded to the AC signal via a series RC circuit at its inverting input terminal.

2. The passive infrared sensor according to claim 1, wherein the first operational amplifier is configured to use a single-supply non-inverting negative feedback AC amplifier circuit with the signal to be amplified connected at the non-inverting input terminal and the AC signal grounded at the inverting input terminal via a series RC circuit.

3. The passive infrared sensor according to claim 1, wherein the first operational amplifier is configured as an inverting negative feedback AC amplifier circuit powered by a single power supply, wherein the signal to be amplified is connected to the inverting input terminal via a series RC circuit, and a corresponding bias voltage is connected to the non-inverting input terminal.

4. The passive infrared sensor according to claim 2 or 3, wherein the number of operational amplifiers in the amplification circuit is two, the first operational amplifier being the primary operational amplifier of the amplification circuit, and the subsequent operational amplifier of the first operational amplifier being the final operational amplifier of the amplification circuit.

5. The passive infrared sensor according to claim 4, wherein the amplification circuit further includes a microcontroller, the microcontroller having at least two ADC ports, wherein the output terminal and non-inverting input terminal of the final stage operational amplifier of the amplification circuit are respectively connected to different ADC ports of the microcontroller via DC paths, corresponding to the microcontroller sampling the output terminal and non-inverting input terminal of the final stage operational amplifier of the amplification circuit through different ADC ports.

6. The passive infrared sensor according to claim 2 or 3, wherein the number of operational amplifiers in the amplification circuit is at least three.

7. The passive infrared sensor according to claim 6, wherein the first operational amplifier is the primary operational amplifier of the amplifier circuit, corresponding to the state in which the first operational amplifier is configured to use a single-supply non-inverting negative feedback AC amplifier circuit, wherein the first operational amplifier is connected to the signal output by the pyroelectric infrared sensor at its non-inverting input terminal, and the state in which the first operational amplifier is configured to use a single-supply inverting negative feedback AC amplifier circuit, wherein the first operational amplifier is connected to the signal output by the pyroelectric infrared sensor at its inverting input terminal via a series RC circuit.

8. The passive infrared sensor according to claim 7, wherein each operational amplifier after the first operational amplifier is configured as a non-inverting negative feedback AC amplifier circuit with its non-inverting input terminal connected to the output terminal of the preceding operational amplifier.

9. The passive infrared sensor according to claim 8, wherein the amplification circuit further includes a microcontroller having at least two ADC ports, wherein the non-inverting input of one of the operational amplifiers after the first operational amplifier and the output of the final operational amplifier of the amplification circuit are respectively connected to different ADC ports of the microcontroller via DC paths, and the microcontroller samples the non-inverting input of one of the operational amplifiers after the first operational amplifier and the output of the final operational amplifier of the amplification circuit respectively using different ADC ports.

10. The passive infrared sensor according to claim 9, wherein the microcontroller samples the non-inverting input and output of the final operational amplifier of the amplifier circuit via different ADC ports, and the non-inverting input and output of the final operational amplifier of the amplifier circuit are respectively connected to different ADC ports of the microcontroller via DC paths.

11. The passive infrared sensor according to claim 6, wherein the amplification circuit further includes a microcontroller, the microcontroller having at least two ADC ports, the microcontroller sampling the non-inverting input and output of the final operational amplifier of the amplification circuit through different ADC ports, and the non-inverting input and output of the final operational amplifier of the amplification circuit being connected to different ADC ports of the microcontroller via DC paths.

12. The passive infrared sensor according to claim 11, wherein the final operational amplifier of the amplifier circuit is configured as an inverting negative feedback AC amplifier circuit powered by a single power supply, wherein the inverting input terminal of the final operational amplifier of the amplifier circuit is connected to the output terminal of the preceding operational amplifier via a series RC circuit, and a corresponding bias voltage is connected to its non-inverting input terminal.

13. The passive infrared sensor according to claim 11, wherein the final stage operational amplifier of the amplifier circuit is configured as a non-inverting negative feedback AC amplifier circuit powered by a single power supply, wherein the non-inverting input terminal of the final stage operational amplifier of the amplifier circuit is connected to the output terminal of the preceding operational amplifier, and the AC signal is grounded at the inverting input terminal via a series RC circuit.

14. A passive infrared sensor, characterized by include: A pyroelectric infrared sensor; and An amplifier circuit is provided, which amplifies the signal output by the pyroelectric infrared sensor and has at least two operational amplifier stages and a microcontroller. Each operational amplifier stage is configured as a negative feedback AC amplifier circuit powered by a single power supply. Each operational amplifier stage is connected to its inverting input via a feedback resistor and to one end of a series RC circuit via its inverting input. The microcontroller has at least two ADC ports. The non-inverting input of one of the operational amplifier stages and the output of the final operational amplifier stage are respectively connected to different ADC ports of the microcontroller via DC paths. The microcontroller samples the non-inverting input of one of the operational amplifier stages and the output of the final operational amplifier stage using different ADC ports. After the operational amplifier whose non-inverting input is connected to the ADC port of the microcontroller via a DC path, all subsequent operational amplifiers are configured as non-inverting negative feedback AC amplifier circuits powered by a single power supply, with their non-inverting inputs connected to the output of the preceding operational amplifier stage.

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