Passive infrared detection device capable of shortening power-on time

Abstract

The utility model provides a passive infrared detection device capable of shortening power-on time, which comprises a pyroelectric infrared sensor and a primary amplification circuit, and the primary amplification circuit is provided with an operational amplifier OP1, a feedback resistor R1 and a first series RC circuit. The anti-phase input end of the operational amplifier OP1 is connected to the output end of the operational amplifier OP1 through the feedback resistor R1 and electrically connected to the signal output end of the pyroelectric infrared sensor through the first series RC circuit, and the in-phase input end of the operational amplifier OP1 is connected with a direct current bias voltage Vref1. The direct current bias voltage Vref1 is set to tend to be the same as the direct current bias voltage Vrefin accessed by the operational amplifier OP1 at the inverted input end through the first series RC circuit within a difference range of less than or equal to 0.5 V, so that the output of the output end of the operational amplifier OP1 can tend to be stable quickly; therefore, the power-on time of the amplifying circuit is shortened.

Description

Technical Field

[0001] This utility model relates to the field of infrared detection, and more specifically to a passive infrared detection device that can shorten power-on time. Background Technology

[0002] With the development of IoT technology and the popularization of low-carbon and environmentally friendly concepts, artificial intelligence, smart home, and smart security technologies are increasingly demanding environmental detection, especially human movement detection. This allows for intelligent control of electrical equipment's operating status by controlling the detection results of human presence or absence. For example, intelligent low-carbon lighting can be achieved by controlling the lighting status of lamps based on the detection results of human presence or absence.

[0003] Passive infrared detection technology is a relatively mature human presence detection technology among existing technologies. Its detection principle is based on a pyroelectric infrared sensor (PIR) detecting cross-zone movements of the human body within a detection area using a multi-window lens to partition the corresponding detection region. This passive infrared detection technology combines the advantages of low cost and the ability to precisely set the detection angle based on the multi-window lens structure design, without infringing on human privacy, thus becoming the most widely used human presence detection technology. Regarding the detection principle of passive infrared detection technology, it is generally believed that as the detection distance increases, because the detected human body is farther away from the infrared detection device using passive infrared detection technology, on the one hand, the amount of infrared light captured by the pyroelectric infrared sensor from the detected human body decreases, thus reducing the strength of the effective signal related to the human body's cross-zone movements in the detection signal; on the other hand, it also makes the areas of the partitions within the detection area larger and more dispersed, thus reducing the number of partitions per unit area and lowering the resolution of the infrared detection device.

[0004] Therefore, in the existing product design of infrared detection devices, to increase the distance detection, it is usually necessary to increase the window area of ​​the multi-window lens to ensure the signal strength associated with human cross-area movement in the detection signal, and to increase the number of windows in the multi-window lens to ensure the resolution of the infrared detection device. In the signal processing rules of the detection signal, based on the empirical understanding of the frequency components of the effective signal corresponding to human cross-area movement in the detection signal, it is believed that the energy of the actual effective signal is concentrated in 0.3Hz to 10Hz, and the energy proportion of the effective signal below 0.3Hz is extremely low, and its intensity will decrease with the increase of detection distance. Correspondingly, when the high-pass cutoff frequency of the amplification circuit of the infrared detection device is less than 0.3Hz, it will not increase the energy proportion of the effective signal, and may also cause baseline drift risk because the high-pass cutoff frequency is close to the DC component. Therefore, the high-pass cutoff frequency of the amplification circuit of the infrared detection device is usually greater than or equal to 0.3Hz. However, due to reasonable product size limitations and the trend towards miniaturization, the window area and number of windows of the multi-window lens cannot be increased simultaneously. As a result, under the aforementioned signal processing rules for the detection signal, the maximum detection distance of existing infrared detection devices, even if they use multi-window lenses with a diameter as high as 80mm, is difficult to exceed 12 meters. Utility Model Content

[0005] One objective of this invention is to provide a passive infrared detection device that can shorten power-on time. When applied to long-distance detection, the passive infrared detection device can reduce the requirements for the window area and number of windows of the multi-window lens, which is beneficial to achieving long-distance detection applications with a smaller size of the multi-window lens, thus adapting to the trend of miniaturized products.

[0006] Another objective of this invention is to provide a passive infrared detection device that can shorten power-on time. The passive infrared detection device utilizes the integral characteristic (charge accumulation due to temperature changes) of the detection signal output by the pyroelectric infrared sensor. In long-distance detection applications, the temperature change corresponding to the cross-zone movement of the human body can generate a near-DC gradual component in the detection signal based on the accumulation of charge. This results in an unexpected, gradually changing signal below 0.3Hz in the detection signal. By using this gradually changing signal below 0.3Hz in the detection signal as an effective signal, the detection of cross-zone movements of the human body at a distance can be achieved.

[0007] Another objective of this invention is to provide a passive infrared detection device that can shorten power-on time. The detection signal output by the pyroelectric infrared sensor has integral characteristics. Based on this characteristic, a slowly varying signal below 0.3Hz is generated in the detection signal, which differs from the effective signal in its generation method. Therefore, this slowly varying signal is usually considered an unexpected interference change. The passive infrared detection device of this invention utilizes the correspondence between this slowly varying signal and human cross-zone movements in long-distance detection application scenarios. By using this slowly varying signal below 0.3Hz in the detection signal as the effective signal, it achieves the detection of long-distance human cross-zone movements. Therefore, it can both ensure the energy ratio of the effective signal in the detection signal based on the integral characteristics of the detection signal output by the pyroelectric infrared sensor, and reduce the energy ratio of interference signals in the detection signal by using a signal that is usually considered an unexpected interference change as the effective signal.

[0008] Another objective of this invention is to provide a passive infrared detection device that can shorten power-on time. This passive infrared detection device utilizes the integral characteristic of the detection signal output by the pyroelectric infrared sensor. By using the unexpected, slowly varying signal below 0.3Hz generated based on this characteristic in the detection signal as the effective signal, it achieves the detection of long-distance human movement across zones. Therefore, based on the integral characteristic of the detection signal output by the pyroelectric infrared sensor, it ensures the energy proportion of the effective signal in the detection signal, thereby reducing the requirements for the window area and number of windows of the multi-window lens. This is beneficial for achieving long-distance detection applications with a smaller multi-window lens size, thus adapting to the trend of miniaturization.

[0009] Another objective of this invention is to provide a passive infrared detection device that can shorten power-on time. The passive infrared detection device is electrically connected to an amplification circuit of the pyroelectric infrared sensor to amplify the AC component of the detection signal output by the pyroelectric infrared sensor. The amplification circuit is configured to have a high-pass cutoff frequency of less than 0.3 Hz, so that the slowly varying signal generated in the detection signal based on the aforementioned integral characteristics can be retained and amplified as an effective signal.

[0010] Another objective of this invention is to provide a passive infrared detection device capable of shortening power-on time. The amplification circuit uses an inverting negative feedback amplification circuit as the primary amplification circuit. Corresponding to the primary amplification circuit is an operational amplifier OP1, a feedback resistor R1, and a first series RC circuit. The output terminal of the operational amplifier OP1 is connected to its inverting input terminal via the feedback resistor R1. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit to receive the detection signal output from the pyroelectric infrared sensor. A direct current is connected to the non-inverting input terminal of the operational amplifier OP1. The DC bias voltage Vref1 is such that the difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit is less than or equal to 0.5V. This ensures that the voltages at the non-inverting and inverting input terminals of the operational amplifier OP1 are close at the beginning of power-on of the passive infrared detection device, allowing the output of the operational amplifier OP1 to stabilize quickly. This shortens the power-on time of the amplifier circuit and solves the problem of excessively long power-on time caused by an excessively low high-pass cutoff frequency when the high-pass cutoff frequency of the amplifier circuit is below 0.3Hz.

[0011] Another objective of this invention is to provide a passive infrared detection device that can shorten power-on time. When the high-pass cutoff frequency of the amplifier circuit is below 0.3Hz, the excessively low high-pass cutoff frequency increases the power-on time, resulting in an excessively long power-on time. This is one reason why existing infrared detection devices typically use a frequency greater than or equal to 0.3Hz as the high-pass cutoff frequency for their amplifier circuits. However, when a DC bias voltage Vref1 is connected to the non-inverting input of the operational amplifier OP1, and this DC bias voltage Vref1 is set to be approximately equal to the DC bias voltage Vrefin connected to the inverting input of the operational amplifier OP1 via the first series RC circuit within a difference range of less than or equal to 0.5V, even with a high-pass cutoff frequency below 0.3Hz, the power-on time of the amplifier circuit can be shortened to less than that of existing infrared detection devices using a frequency greater than or equal to 0.3Hz as the high-pass cutoff frequency. Therefore, this design is beneficial for the commercial application and widespread adoption of the passive infrared detection device and has significant commercial value.

[0012] To achieve at least one of the above objectives, according to one aspect of the present invention, a passive infrared detection device capable of shortening power-on time is provided, the passive infrared detection device comprising:

[0013] A pyroelectric infrared sensor; and

[0014] An amplifier circuit is provided, wherein the primary amplifier circuit is an inverting negative feedback amplifier circuit, and the primary amplifier circuit includes an operational amplifier OP1, a feedback resistor R1, and a first series RC circuit. The output terminal of the operational amplifier OP1 is connected to the inverting input terminal of the operational amplifier OP1 via the feedback resistor R1. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit to receive the detection signal output from the signal output terminal of the pyroelectric infrared sensor. A DC bias voltage Vref1 is connected to the non-inverting input terminal of the operational amplifier OP1. The DC bias voltage Vref1 is set to be similar to the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit within a difference range of less than or equal to 0.5V.

[0015] In one embodiment, the amplification circuit is configured to provide the DC bias voltage Vref1 to the non-inverting input of the operational amplifier OP1 of the primary amplification circuit using a first voltage divider circuit. The first voltage divider circuit has a first voltage divider resistor and a first resistor to ground. One end of the first resistor to ground is grounded, and the other end of the first resistor to ground is connected to the DC supply voltage via the first voltage divider resistor. The non-inverting input of the operational amplifier OP1 of the primary amplification circuit is electrically connected between the first voltage divider resistor and the first resistor to ground.

[0016] In one embodiment, the primary amplifier circuit is configured to have a high-pass cutoff frequency of less than 0.3 Hz.

[0017] In one embodiment, the operational amplifier OP1 is configured to be powered by a single power supply.

[0018] In one embodiment, the amplification circuit further includes a boost divider circuit, wherein the boost divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit and the voltage matching resistor, and is connected to the DC power supply voltage via the first series RC circuit and the voltage divider resistor.

[0019] In one embodiment, the voltage matching resistor of the boost divider circuit is further connected in parallel with a capacitor.

[0020] In one embodiment, the amplification circuit further includes a boost divider circuit, wherein the boost divider circuit has a voltage divider resistor, a ground resistor, and a DC blocking capacitor, wherein one end of the ground resistor is grounded, the other end of the ground resistor is connected to a DC power supply voltage via the voltage divider resistor, and is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the DC blocking capacitor, wherein the operational amplifier OP1 is electrically connected at its inverting input terminal between the voltage divider resistor and the ground resistor via the first series RC circuit.

[0021] In one embodiment, the operational amplifier OP1 is configured to be powered by a dual power supply.

[0022] In one embodiment, the amplification circuit further includes a step-down voltage divider circuit, wherein the step-down voltage divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit and the voltage matching resistor, and is connected to a negative DC power supply voltage via the first series RC circuit and the voltage divider resistor.

[0023] In one embodiment, the amplification circuit further includes a step-down voltage divider circuit, wherein the step-down voltage divider circuit has a positive voltage divider resistor, a negative voltage divider resistor, and a DC blocking capacitor, wherein one end of the negative voltage divider resistor is connected to a negative DC power supply voltage, and the other end of the negative voltage divider resistor is connected to a positive DC power supply voltage via the positive voltage divider resistor and electrically connected to the signal output terminal of the pyroelectric infrared sensor via the DC blocking capacitor, wherein the operational amplifier OP1 is electrically connected at its inverting input terminal between the positive voltage divider resistor and the negative voltage divider resistor via the first series RC circuit.

[0024] In one embodiment, the non-inverting input of the operational amplifier OP1 is grounded.

[0025] In one embodiment, the amplification circuit uses an inverting negative feedback amplification circuit as the secondary amplification circuit. The secondary amplification circuit has an operational amplifier OP2, a feedback resistor R2, and a second series RC circuit. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 via the feedback resistor R2. The inverting input terminal of the operational amplifier OP2 is electrically connected to the output terminal of the operational amplifier OP1 via the second series RC circuit to receive the detection signal amplified by the primary amplification circuit.

[0026] In one embodiment, a DC bias voltage Vref2 is connected to the non-inverting input terminal of the operational amplifier OP2. The DC bias voltage Vref2 connected to the non-inverting input terminal of the operational amplifier OP2 is set to be within a difference range of less than or equal to 0.5V, and is similar to the DC bias voltage Vref1 connected to the non-inverting input terminal of the operational amplifier OP1.

[0027] In one embodiment, the amplification circuit is configured to provide the DC bias voltage Vref2 to the non-inverting input of the operational amplifier OP2 of the secondary amplification circuit via a second voltage divider circuit. The second voltage divider circuit has a second voltage divider resistor and a second resistor to ground. One end of the second resistor to ground is grounded, and the other end of the second resistor to ground is connected to the DC supply voltage via the second voltage divider resistor. The non-inverting input of the operational amplifier OP2 of the secondary amplification circuit is electrically connected between the second voltage divider resistor and the second resistor to ground.

[0028] The further objectives and advantages of this invention will become fully apparent from the following description and accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the principle of passive infrared detection technology.

[0030] Figure 2 This is a schematic diagram of the circuit structure of a passive infrared detection device according to an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0032] Figure 4A This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0033] Figure 4B This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0036] Figure 7A This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0037] Figure 7B This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0038] Figure 8 This is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] 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.

[0042] For a full understanding of this utility model, please refer to the accompanying drawings in the specification of this utility model. Figure 1 As shown, the principle of passive infrared detection technology is illustrated. As previously mentioned, passive infrared detection technology uses a multi-window lens 10P to partition the corresponding detection area, and a pyroelectric infrared sensor 20P to detect the cross-regional movements of the human body within the detection area. The photosensitive surface of the pyroelectric infrared sensor 20P is provided with at least one pair of pyroelectric units 21P. The pair of pyroelectric units 21P consists of two pyroelectric units 21P connected in series in opposite directions, so that the pair of pyroelectric units 21P can cancel out ambient temperature drift and common-mode interference and be sensitive only to dynamic temperature differences.

[0043] In other words, the partition formed by the window of the multi-window lens 10P through the photosensitive surface of the pyroelectric infrared sensor 20P also includes a bright area and a dark area corresponding to the pair of pyroelectric units 21P respectively, and a blind area is formed between the bright area and the dark area. Since the pair of pyroelectric units 21P are two pyroelectric units 21P connected in series in opposite directions, the currents formed by the same temperature change in the bright area and the dark area within the same partition are opposite in direction and cancel each other out. Therefore, the overall temperature change of the partition corresponding to any window will not cause fluctuations in the detection signal output by the pyroelectric infrared sensor 20P. However, when a human body, as a heat source, passes through the partition corresponding to any window, the light spot formed by the heat source through the window on the photosensitive surface of the pyroelectric unit 21P will enter the pair of pyroelectric units 21P successively as the human body moves. Thus, a dynamic temperature difference change can be generated between the pair of pyroelectric units 21P, causing fluctuations in the detection signal output by the pyroelectric infrared sensor 20P.

[0044] It is understandable that, based on the electrical characteristics of the pyroelectric unit 21P, even if there is a temperature difference between a pair of pyroelectric units 21P, as long as the temperature difference does not change, the potential distribution between the pair of pyroelectric units 21P will tend to be balanced and will not cause fluctuations in the detection signal output by the pyroelectric infrared sensor 20P. That is, the pair of pyroelectric units 21P is only sensitive to dynamic temperature differences. The movement of the human body as a heat source in the bright or dark area will theoretically not cause fluctuations in the detection signal output by the pyroelectric infrared sensor 20P because it does not constitute a cross-area movement. Therefore, when a human body, acting as a heat source, passes through a partition corresponding to any window, the fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P correspond to the human body's actions of crossing zones when entering a bright zone, leaving a bright zone, entering a dark zone, and leaving a dark zone. Furthermore, when the fluctuation corresponding to the human body's actions of entering a bright zone is a positive fluctuation, the fluctuation corresponding to the human body's actions of leaving a bright zone is a negative fluctuation, the fluctuation corresponding to the human body's actions of entering a dark zone is a negative fluctuation, and the fluctuation corresponding to the human body's actions of leaving a dark zone is a positive fluctuation.

[0045] Therefore, the time span of the fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P is mainly related to the time span of the human body completing the corresponding cross-zone action. In applications requiring long-distance detection based on high or side mounting, because the areas of the partitions corresponding to different windows are large and dispersed, the cross-zone actions of the human body passing through the corresponding partitions are not continuous. Consequently, the corresponding fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P are also not continuous. Therefore, the frequency of the corresponding fluctuation changes directly corresponds to the time span of the fluctuation changes and is related to the human body's movement speed. Thus, within the normal human movement speed range, even in long-distance detection applications, the frequency of the fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P, as an effective signal, is mainly concentrated in the range of 0.3Hz to 10Hz.

[0046] Furthermore, when a human body, acting as a heat source, passes through multiple partitions corresponding to different windows at a constant speed, the density of the partitions and the density of the light and dark areas within each partition are directly related to the density of fluctuations in the detection signal output by the pyroelectric infrared sensor 20P. That is, the higher the resolution of the infrared detection device, the denser the fluctuations in the detection signal output by the pyroelectric infrared sensor 20P, thereby making the corresponding fluctuations in the detection signal output by the pyroelectric infrared sensor 20P more coherent. Thus, in subsequent signal processing, the detectability of the effective signal in terms of intensity and frequency can be improved based on the coherence of the fluctuations as an effective signal.

[0047] Furthermore, the higher the resolution of the infrared detection device, the denser the fluctuations in the detection signal output by the pyroelectric infrared sensor 20P. This increased density of fluctuations in the output signal may lead to a superposition of these fluctuations, thereby increasing the intensity and frequency of the effective signal. In other words, with improved resolution of the infrared detection device, the frequency of the effective signal in the detection signal may be increased, further concentrating within the 0.3Hz to 10Hz range at frequencies deviating from 0.3Hz.

[0048] Therefore, in the design of existing commercial infrared detection devices, to increase the detection distance, it is usually necessary to increase the window area of ​​the multi-window lens 10P in order to ensure the signal strength of the detection signal related to human cross-regional movements, and to increase the number of windows of the multi-window lens to ensure the resolution of the infrared detection device. In the signal processing rules of the detection signal, a frequency greater than or equal to 0.3Hz is generally used as the high-pass cutoff frequency of the corresponding amplifier circuit, so as to ensure the energy ratio of the effective signal while avoiding the risk of baseline drift caused by the high-pass cutoff frequency being close to the DC component.

[0049] In the passive infrared detection device of this invention, the passive infrared detection device utilizes the integral characteristic (charge accumulation due to temperature change) of the detection signal output by the pyroelectric infrared sensor 20P. Corresponding to the application scenario of long-distance detection, although the movement of the human body as a heat source in the bright or dark area does not theoretically form a fluctuation in the detection signal output by the pyroelectric infrared sensor 20P because it does not constitute a cross-area movement, the temperature change corresponding to the cross-area movement of the human body can generate a near-DC gradual component in the detection signal based on the accumulation change of charge. This results in an unexpected gradual signal below 0.3Hz in the detection signal. By using this gradual signal below 0.3Hz in the detection signal as an effective signal, the detection of human body cross-area movement at a distance is achieved.

[0050] In other words, the detection signal output by the pyroelectric infrared sensor 20P has an integral characteristic. Based on this characteristic of the pyroelectric infrared sensor 20P, the slowly varying signal below 0.3Hz generated in the detection signal is different from the effective signal in terms of generation method. Therefore, this slowly varying signal is usually regarded as an unexpected interference change. The passive infrared detection device of this utility model utilizes the correspondence between this slowly varying signal and human cross-zone movement in long-distance detection application scenarios, and uses the slowly varying signal below 0.3Hz in the detection signal as the effective signal to realize the detection of human cross-zone movement at a long distance. Therefore, it can ensure the energy ratio of the effective signal in the detection signal based on the integral characteristic of the detection signal output by the pyroelectric infrared sensor 20P, and reduce the energy ratio of the interference signal in the detection signal by using the signal that is usually regarded as an unexpected interference change as the effective signal.

[0051] Specifically, as mentioned above, when a human body, acting as a heat source, passes through a partition corresponding to any window, the fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P correspond to the human body's actions of crossing zones when entering a bright zone, leaving a bright zone, entering a dark zone, and leaving a dark zone. Furthermore, when the fluctuation corresponding to the human body's actions of entering a bright zone is a positive fluctuation, the fluctuation corresponding to the human body's actions of leaving a bright zone is a negative fluctuation, the fluctuation corresponding to the human body's actions of entering a dark zone is a negative fluctuation, and the fluctuation corresponding to the human body's actions of leaving a dark zone is a positive fluctuation. While the movement of a human body, acting as a heat source, within the bright or dark zone theoretically does not constitute a cross-zone movement and therefore will not cause fluctuations in the detection signal output by the pyroelectric infrared sensor 20P, after the human body enters the bright zone, the pyroelectric unit 21P corresponding to the bright zone in the pair of pyroelectric units 21P will accumulate charge based on the temperature changes caused by the human body's movement, thereby generating a near-DC gradual change component in the detection signal, such as a near-DC positive gradual change component. Similarly, after the human body enters the dark zone, the pyroelectric unit 21P corresponding to the dark zone in the pair of pyroelectric units 21P will also accumulate charge based on the temperature changes caused by the human body's movement, thereby generating a near-DC gradual change component in the detection signal, such as a near-DC negative gradual change component. This results in a gradually changing signal with a change period close to the time it takes for the human body to pass through the corresponding zone. In long-distance detection applications with a detection distance greater than 10 meters, within the normal human body movement speed range, the frequency of this gradually changing signal is concentrated in the frequency range below 0.3 Hz.

[0052] It is understood that in the description of this utility model, the application scenario of long-distance detection greater than 10 meters is not limited to the application scenario of the passive infrared detection device, but rather indicates that by using the aforementioned slowly varying signal below 0.3Hz in the detection signal as the effective signal, the maximum effective detection distance of the passive infrared detection device of this utility model can be increased to greater than 10 meters. Thus, based on the requirement of long-distance detection, the requirements for the window area and number of windows of the multi-window lens 10P are reduced, which is conducive to realizing long-distance detection applications with a smaller size of the multi-window lens 10P and adapting to the trend of miniaturization products.

[0053] It is worth mentioning that the maximum effective detection distance of the passive infrared detection device of this utility model has been increased to more than 10 meters. The passive infrared detection device has a variety of specific application scenarios. For example, the passive infrared detection device can achieve detection of a large area in low installation scenarios with a large detection angle setting, or it can achieve detection of a large area in high installation scenarios with a small detection angle setting, or it can achieve detection of a long distance and / or a large area in side installation scenarios.

[0054] Further reference is made to the accompanying drawings of this utility model specification. Figure 2 As shown, the circuit structure of a passive infrared detection device according to an embodiment of the present invention is illustrated. The passive infrared detection device includes a pyroelectric infrared sensor 20 and an amplifier circuit 30 capable of amplifying the AC component of the detection signal output by the pyroelectric infrared sensor 20. The amplifier circuit 30 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 to amplify the AC component of the detection signal output by the pyroelectric infrared sensor 20 from its signal output terminal. It is set to have a high-pass cutoff frequency below 0.3Hz, so that the slowly varying signal generated based on the aforementioned integration characteristics in the detection signal can be retained and amplified as an effective signal, thereby increasing the maximum effective detection distance of the passive infrared detection device to greater than 10 meters. Preferably, the high-pass cutoff frequency of the amplifier circuit 30 is set to less than or equal to 0.2Hz, which helps to increase the energy proportion of the slowly varying signal generated based on the aforementioned integration characteristics, thereby improving the detectability of the effective signal in terms of intensity and frequency.

[0055] Specifically, in this embodiment of the present invention, the amplifier circuit 30 uses an inverting negative feedback amplifier circuit as the primary amplifier circuit 31, and the primary amplifier circuit 31 is set to have a high-pass cutoff frequency of less than 0.3Hz.

[0056] In the state where the amplifier circuit 30 is in the form of an inverting negative feedback amplifier circuit as the primary amplifier circuit 31, the primary amplifier circuit 31 has an operational amplifier OP1, a feedback resistor R1, and a first series RC circuit. The output terminal of the operational amplifier OP1 is connected to the inverting input terminal of the operational amplifier OP1 through the feedback resistor R1. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 through the first series RC circuit to receive the detection signal output from the signal output terminal of the pyroelectric infrared sensor 20. A DC bias voltage Vref1 is connected to the non-inverting input terminal of the operational amplifier OP1, thus forming an inverting negative feedback amplifier circuit.

[0057] Understandably, in Figure 2 In the circuit structure of the passive infrared detection device shown, the inverting input terminal of the amplifier OP1 is sequentially electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via a resistor and a capacitor in the first series RC circuit. This forms a structural feature where the inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor 20 via the first series RC circuit. The relative positions of the resistors and capacitors connected in series in the first series RC circuit do not constitute a limitation of this invention. That is, in some embodiments of this invention, the inverting input terminal of the amplifier OP1 can also be sequentially electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via a capacitor and a resistor in the first series RC circuit.

[0058] It is worth mentioning that the high-pass cutoff frequency f of the primary amplifier circuit 31 is related to the time constant of the first series RC circuit. The lower the high-pass cutoff frequency f of the primary amplifier circuit 31, the larger the product of the resistance and capacitance values ​​in the first series RC circuit. Therefore, the lower the high-pass cutoff frequency f of the primary amplifier circuit 31, the longer the charging and discharging time of the first series RC circuit. Correspondingly, the power-on time of the amplifier circuit 30 is longer, as it represents the time from power-on to the point where it can stably amplify and output the input signal. This is one of the reasons why existing infrared detection devices in practical applications typically use a frequency greater than or equal to 0.3Hz as the high-pass cutoff frequency of the corresponding amplifier circuit. In other words, when the amplifier circuit 30 of this invention is set to have a high-pass cutoff frequency lower than 0.3Hz, the power-on time of the amplifier circuit 30 will be excessively long.

[0059] Therefore, in this embodiment of the present invention, the DC bias voltage Vref1 is set to be similar to the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit within a difference range of less than or equal to 0.5V. This allows the voltages at the non-inverting and inverting input terminals of the operational amplifier OP1 to approach each other at the beginning of power-on of the passive infrared detection device, enabling the output of the operational amplifier OP1 to quickly stabilize. Consequently, the power-on time of the amplifier circuit 30 can be shortened. This solves the problem of excessively long power-on time caused by an excessively low high-pass cutoff frequency of the amplifier circuit when the high-pass cutoff frequency of the amplifier circuit is below 0.3Hz.

[0060] It is understood that setting the DC bias voltage Vref1 to be approximately the same as the DC bias voltage Vrefin within a difference range of less than or equal to 0.5V will not affect the shortening effect on the power-on time of the primary amplifier circuit 31, regardless of the high-pass cutoff frequency of the primary amplifier circuit 31. In other words, the amplifier circuit 30 of this invention is also applicable to existing infrared detection devices with a high-pass cutoff frequency greater than or equal to 0.3Hz.

[0061] For example, in this embodiment of the present invention, the inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via the first series RC circuit. Then, the connection between the first series RC circuit and the signal output terminal of the pyroelectric infrared sensor 20 corresponds to... Figure 2 In the absence of a voltage divider circuit, the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit corresponds to the DC bias voltage Vrefpir output from the signal output terminal of the pyroelectric infrared sensor 20. The corresponding DC bias voltage Vref1 should be set within a difference range of less than or equal to 0.5V to be similar to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20.

[0062] As a further example, such as Figure 3 As shown, in Figure 2 Based on the structure of the amplifier circuit 30 shown, the amplifier circuit 30 is configured to provide the DC bias voltage Vref1 to the non-inverting input terminal of the operational amplifier OP1 of the primary amplifier circuit 31 using a first voltage divider circuit 311. The first voltage divider circuit 311 has a first voltage divider resistor 3111 and a first ground resistor 3112. One end of the first ground resistor 3112 is grounded, and the other end of the first ground resistor 3112 is connected to the DC supply voltage via the first voltage divider resistor 3111. The non-inverting input terminal of the operational amplifier OP1 of the primary amplifier circuit 31 is electrically connected between the first voltage divider resistor 3111 and the first ground resistor 3112. Thus, the required DC bias voltage Vref1 is provided to the non-inverting input terminal of the operational amplifier OP1 based on the magnitude of the DC supply voltage connected to the first voltage divider circuit 311 and the ratio between the first voltage divider resistor 3111 and the first ground resistor 3112.

[0063] Specifically, between the first series RC circuit and the signal output terminal of the pyroelectric infrared sensor 20, corresponding to Figure 2 and Figure 3Without a voltage divider circuit, the DC bias voltage Vrefin connected to the inverting input of operational amplifier OP1 via the first series RC circuit corresponds to the DC bias voltage Vrefpir output from the signal output terminal of pyroelectric infrared sensor 20. The DC bias voltage Vrefpir output from the signal output terminal of pyroelectric infrared sensor 20 is typically low. Therefore, in the case of operational amplifier OP1 being powered by a single power supply, based on the matching requirement between the DC bias voltage Vrefin connected to the inverting input of operational amplifier OP1 via the first series RC circuit and its supply voltage, or based on the amplification factor requirement for the magnitude of the DC bias voltage Vrefin connected to the inverting input of operational amplifier OP1 via the first series RC circuit, in some embodiments of this invention, it can also correspond to... Figure 4A and Figure 4B In respectively Figure 2 and Figure 3 Based on the structure of the amplifier circuit 30 shown, a boost divider circuit 32 is further provided. The boost divider circuit 32 has a voltage divider resistor 321 and a voltage matching resistor 322. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via the first series RC circuit and the voltage matching resistor 322, and is also connected to a DC power supply voltage via the first series RC circuit and the voltage divider resistor 321. For example, it can be connected to the power supply terminal of the pyroelectric infrared sensor 20 via the first series RC circuit and the voltage divider resistor 321. The power supply terminal of the pyroelectric infrared sensor 20 is connected to a DC power supply voltage. In this way, by utilizing the matching setting of the self-impedance of the pyroelectric infrared sensor 20 and the boost divider circuit 32, the voltage at one end of the voltage matching resistor 322 electrically connected to the pyroelectric infrared sensor 20 corresponds to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20. This allows the voltage at the other end of the voltage matching resistor 322 to be boosted to match the magnitude requirement of the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 through the first series RC circuit.

[0064] It is worth mentioning that, Figure 4A and Figure 4BBased on the illustrated amplifier circuit 30, to ensure that the voltage at one end of the voltage matching resistor 322 electrically connected to the pyroelectric infrared sensor 20 corresponds to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, and that the voltage at the other end of the voltage matching resistor 322 matches the magnitude of the DC bias voltage Vrefin connected to the inverting input of the operational amplifier OP1 via the first series RC circuit, high precision and stability of the resistance value of the voltage matching resistor 322 are required. Therefore, if the resistance value of the voltage matching resistor 322 deviates in actual use or is affected by environmental factors, impedance mismatch can easily occur, leading to attenuation of the detection signal connected to the inverting input of the operational amplifier OP1 via the first series RC circuit. In view of this, in another embodiment of the present invention, the amplification circuit 30 further includes a capacitor connected in parallel with the voltage matching resistor 322, so as to optimize impedance matching and avoid signal attenuation problems when the resistance value of the voltage matching resistor 322 in actual use deviates or is affected by environmental factors, based on the method of connecting the capacitor in parallel with the voltage matching resistor 322.

[0065] It is worth mentioning that the boost divider circuit 32 is configured to boost the DC bias voltage Vrefin of the operational amplifier OP1 connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit relative to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20 when the operational amplifier OP1 is powered by a single power supply, based on the matching requirements between the DC bias voltage Vrefin and the power supply voltage of the operational amplifier OP1 connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit, or based on the amplification factor requirement for the magnitude of the DC bias voltage Vrefin of the operational amplifier OP1 connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit. The specific circuit configuration of the boost divider circuit 32 is diverse, and this utility model does not limit it.

[0066] For example, such as Figure 5 As shown, in Figure 2Another circuit configuration of the boost divider circuit 32A, further configured on the basis of the amplifier circuit 30 shown, is illustrated. The boost divider circuit 32A includes a voltage divider resistor 321A, a ground resistor 322A, and a DC blocking capacitor 323A. One end of the ground resistor 322A is grounded, and the other end is connected to a DC power supply voltage via the voltage divider resistor 321A. For example, it is connected to the power supply terminal of the pyroelectric infrared sensor 20 to receive a DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor 20, and is electrically connected to the signal output of the pyroelectric infrared sensor 20 via the DC blocking capacitor 323A. The operational amplifier OP1 is electrically connected at its inverting input terminal between the voltage divider resistor 321A and the ground resistor 322A via the first series RC circuit. This allows the operational amplifier OP1 to both access the AC component of the detection signal output from the pyroelectric infrared sensor 20 at its inverting input terminal via the first series RC circuit and to access the DC supply voltage at its inverting input terminal via the first series RC circuit, whereby the ground resistor 322A is connected to the voltage divider resistor 321A via the DC supply voltage, and the DC bias voltage Vrefin, which is related to the ratio between the voltage divider resistor 321A and the ground resistor 322A, is connected to its inverting input terminal via the first series RC circuit.

[0067] Specifically, in the above embodiments of this utility model, the secondary amplifier circuit 33 of the amplifier circuit 30 is also an example of using an inverting negative feedback amplifier circuit. The secondary amplifier circuit 33 has an operational amplifier OP2, a feedback resistor R2, and a second series RC circuit. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R2. The inverting input terminal of the operational amplifier OP2 is electrically connected to the output terminal of the operational amplifier OP1 through the second series RC circuit to receive the detection signal amplified by the primary amplifier circuit 31. A DC bias voltage Vref2 is connected to the non-inverting input terminal of the operational amplifier OP2, thus forming an inverting negative feedback amplifier circuit.

[0068] It is understandable that, when the primary amplifier circuit 31 is set to have a high-pass cutoff frequency below 0.3Hz, in order to maintain the high-pass cutoff frequency of the amplifier circuit 30 at a frequency below 0.3Hz, the secondary amplifier circuit 33 is also set to have a high-pass cutoff frequency below 0.3Hz. Based on the foregoing description, the lower the high-pass cutoff frequency f of the primary amplifier circuit 31, the longer the charging and discharging time of the first series RC circuit. That is, the lower the high-pass cutoff frequency f of the primary amplifier circuit 31, the longer it takes for the output of the operational amplifier OP1 to form a stable output. The secondary amplifier circuit 33 takes the signal output from the primary amplifier circuit 31 as its input signal, and the inverting input terminal of the operational amplifier OP2 is electrically connected to the output terminal of the operational amplifier OP1 via the second series RC circuit. Therefore, the output of the operational amplifier OP1 can quickly stabilize, which means that the signal connected to the inverting input of the operational amplifier OP2 via the second series RC circuit can quickly stabilize. Thus, setting the DC bias voltage Vref1 to be the same as the DC bias voltage Vrefin connected to the inverting input of the operational amplifier OP1 via the first series RC circuit within a difference range of less than or equal to 0.5V can synchronously make the signal connected to the inverting input of the operational amplifier OP2 via the second series RC circuit quickly stabilize, thereby shortening the power-on time of the amplifier circuit 30.

[0069] In the secondary amplifier circuit 33 of the amplifier circuit 30, the inverting negative feedback amplifier circuit is also adopted. In order to further shorten the power-on time of the amplifier circuit 30, the DC bias voltage Vref2 connected to the non-inverting input terminal of the operational amplifier OP2 is preferably set to be within a difference range of less than or equal to 0.5V, which is similar to the DC bias voltage Vref1 connected to the non-inverting input terminal of the operational amplifier OP1.

[0070] Specifically, in this utility model, the corresponding Figure 3 and Figure 4BIn the illustrated embodiment, the amplifier circuit 30 is configured to provide the DC bias voltage Vref2 to the non-inverting input of the operational amplifier OP2 of the secondary amplifier circuit 33 via a second voltage divider circuit 331. The second voltage divider circuit 331 has a second voltage divider resistor 3311 and a second resistor to ground 3312. One end of the second resistor to ground 3312 is grounded, and the other end of the second resistor to ground 3312 is connected to the DC supply voltage via the second voltage divider resistor 3311. The non-inverting input of the operational amplifier OP2 of the secondary amplifier circuit 33 is electrically connected between the second voltage divider resistor 3311 and the second resistor to ground 3312. Thus, the required DC bias voltage Vref2 is provided to the non-inverting input of the operational amplifier OP2 based on the magnitude of the DC supply voltage connected to the second voltage divider circuit 331 and the ratio between the second voltage divider resistor 3311 and the second resistor to ground 3312.

[0071] It is worth mentioning that, Figures 4A to 5 In the illustrated embodiment, both operational amplifiers OP1 and OP2 are shown to be powered by a single power supply. Using a single power supply simplifies the power supply structure of the amplifier circuit 30 and reduces its power supply cost. However, in this utility model, corresponding to... Figure 2 and Figure 3 In the illustrated embodiments, the power supply method of operational amplifier OP1 and operational amplifier OP2 does not constitute a limitation on this utility model. That is, in some embodiments of this utility model, operational amplifier OP1 and / or operational amplifier OP2 can also correspond to... Figure 6 It is configured to use a dual power supply.

[0072] Specifically, the DC bias voltage Vrefpir output from the signal output terminal of the pyroelectric infrared sensor 20 is typically low. When the operational amplifier OP1 is powered by a dual power supply, based on the matching requirement between the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit and its supply voltage, or based on the amplification factor requirement for the magnitude of the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit, in some embodiments of this invention, it is also possible to correspond to... Figure 7A and Figure 7B exist Figure 6Based on the structure of the amplifier circuit 30 shown, a step-down voltage divider circuit 34 is further provided. The step-down voltage divider circuit 34 has a voltage divider resistor 341 and a voltage matching resistor 342. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 through the first series RC circuit and the voltage matching resistor 342, and is connected to a negative DC power supply voltage through the first series RC circuit and the voltage divider resistor 341. In this way, by utilizing the matching setting of the self-impedance of the pyroelectric infrared sensor 20 and the step-down voltage divider circuit 34, the voltage at one end of the voltage matching resistor 342 connected to the pyroelectric infrared sensor 20 corresponds to the state of the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, so that the voltage at the other end of the voltage matching resistor 342 can be pulled down to match the magnitude requirement of the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 through the first series RC circuit.

[0073] Similarly, to ensure that the voltage at one end of the voltage matching resistor 342 electrically connected to the pyroelectric infrared sensor 20 corresponds to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, and that the voltage at the other end of the voltage matching resistor 342 matches the DC bias voltage Vrefin connected to the inverting input of the operational amplifier OP1 via the first series RC circuit, high precision and stability of the resistance value of the voltage matching resistor 342 are required. Therefore, when the resistance value of the voltage matching resistor 342 in actual use deviates or is affected by environmental factors, impedance mismatch can easily occur, leading to attenuation of the detection signal connected to the inverting input of the operational amplifier OP1 via the first series RC circuit. In view of this, in another embodiment of the present invention, the amplification circuit 30 further includes a capacitor connected in parallel with the voltage matching resistor 342. Based on this parallel capacitor connection, when the resistance value of the voltage matching resistor 342 in actual use deviates or is affected by environmental factors, impedance matching is optimized to avoid signal attenuation.

[0074] It is understood that the step-down voltage divider circuit 34 is configured to, when the operational amplifier OP1 is powered by a dual power supply, based on the matching requirement between the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit and its supply voltage, or based on the amplification factor requirement for the magnitude of the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit, pull the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit lower relative to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20. For example, it pulls the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit lowered to near ground potential. The non-inverting input terminal of the operational amplifier OP1 can optionally correspond to... Figure 7B By grounding, the DC bias voltage Vref1 tends to be the same as the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20 within a difference range of less than or equal to 0.5V. This helps to simplify the power supply structure of the amplifier circuit 30 and reduce the power supply cost of the amplifier circuit 30.

[0075] It is worth mentioning that, based on the purpose of pulling down the DC bias voltage Vrefin, which is connected to the inverting input terminal of the operational amplifier OP1 through the first series RC circuit, relative to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, the specific circuit configuration of the step-down voltage divider circuit 34 is diverse, and this utility model does not limit it.

[0076] For example, such as Figure 8 As shown, in Figure 6Another circuit configuration of the step-down voltage divider circuit 34A, further configured based on the structure of the amplifier circuit 30 shown, is illustrated. The step-down voltage divider circuit 34A includes a positive voltage divider resistor 341A, a negative voltage divider resistor 342A, and a DC blocking capacitor 343A. One end of the negative voltage divider resistor 342A is connected to a negative DC power supply voltage, and the other end of the negative voltage divider resistor 342A is connected to a positive DC power supply voltage via the positive voltage divider resistor 341A. It is also electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via the DC blocking capacitor 343A. The operational amplifier OP1 is electrically connected at its inverting input terminal between the positive voltage divider resistor 341A and the negative voltage divider resistor 342A via the first series RC circuit. This allows the operational amplifier OP1 to both access the AC component of the detection signal output from the pyroelectric infrared sensor 20 at its inverting input terminal via the first series RC circuit and access the DC bias voltage Vrefin, which is related to the ratio between the positive voltage divider resistor 341A and the negative voltage divider resistor 342A, at its inverting input terminal via the first series RC circuit.

[0077] Those skilled in the art should understand that, based on the structure of the passive infrared detection device in the above embodiments of this utility model, the operational amplifier OP1 of the primary amplifier circuit 31 and the operational amplifier OP2 of the secondary amplifier circuit 33 can be integrated into the same chip. The amplifier circuit 30 is also suitable for further integration with conventional improvement methods to enhance the relevant performance of the amplifier circuit 30. For example, a capacitor can be connected between the non-inverting input terminal and the inverting input terminal of the operational amplifier to enhance the anti-interference performance of the amplifier circuit 30. Another example is to connect a capacitor in parallel with the feedback resistor of the inverting negative feedback amplifier circuit to prevent the self-oscillation of the operational amplifier and filter high-frequency interference to ensure the stability of the amplifier circuit 30. A capacitor can also be connected to ground at the power supply terminal of the operational amplifier to purify the power network and ensure the anti-interference performance of the amplifier circuit 30. This utility model does not limit this.

[0078] 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.

[0079] 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 detection device capable of shortening power-on time, characterized in that, include: A pyroelectric infrared sensor; and An amplifier circuit is provided, wherein the primary amplifier circuit is an inverting negative feedback amplifier circuit, and the primary amplifier circuit includes an operational amplifier OP1, a feedback resistor R1, and a first series RC circuit. The output terminal of the operational amplifier OP1 is connected to the inverting input terminal of the operational amplifier OP1 via the feedback resistor R1. The inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit to receive the detection signal output from the signal output terminal of the pyroelectric infrared sensor. A DC bias voltage Vref1 is connected to the non-inverting input terminal of the operational amplifier OP1. The DC bias voltage Vref1 is set to be similar to the DC bias voltage Vrefin connected to the inverting input terminal of the operational amplifier OP1 via the first series RC circuit within a difference range of less than or equal to 0.5V.

2. The passive infrared detection device according to claim 1, wherein the amplification circuit is configured to provide the DC bias voltage Vref1 to the non-inverting input terminal of the operational amplifier OP1 of the primary amplification circuit via a first voltage divider circuit, wherein the first voltage divider circuit has a first voltage divider resistor and a first ground resistor, wherein one end of the first ground resistor is grounded, and the other end of the first ground resistor is connected to the DC power supply voltage via the first voltage divider resistor, and the non-inverting input terminal of the operational amplifier OP1 of the primary amplification circuit is electrically connected between the first voltage divider resistor and the first ground resistor.

3. The passive infrared detection device according to claim 1, wherein the primary amplifier circuit is configured to have a high-pass cutoff frequency of less than 0.3 Hz.

4. The passive infrared detection device according to any one of claims 1 to 3, wherein the operational amplifier OP1 is configured to be powered by a single power supply.

5. The passive infrared detection device according to claim 4, wherein the amplification circuit further includes a boost divider circuit, wherein the boost divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit and the voltage matching resistor, and is connected to the DC power supply voltage via the first series RC circuit and the voltage divider resistor.

6. The passive infrared detection device according to claim 5, wherein the voltage matching resistor of the boost divider circuit is further connected in parallel with a capacitor.

7. The passive infrared detection device according to claim 4, wherein the amplification circuit further includes a boost divider circuit, wherein the boost divider circuit has a voltage divider resistor, a ground resistor and a DC blocking capacitor, wherein one end of the ground resistor is grounded, the other end of the ground resistor is connected to a DC power supply voltage through the voltage divider resistor and electrically connected to the signal output terminal of the pyroelectric infrared sensor through the DC blocking capacitor, wherein the operational amplifier OP1 is electrically connected at its inverting input terminal between the voltage divider resistor and the ground resistor through the first series RC circuit.

8. The passive infrared detection device according to claim 1 or 3, wherein the operational amplifier OP1 is configured to be powered by a dual power supply.

9. The passive infrared detection device according to claim 8, wherein the amplification circuit further includes a step-down voltage divider circuit, wherein the step-down voltage divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the first series RC circuit and the voltage matching resistor, and is connected to a negative DC power supply voltage via the first series RC circuit and the voltage divider resistor.

10. The passive infrared detection device according to claim 9, wherein the non-inverting input terminal of the operational amplifier OP1 is grounded.

11. The passive infrared detection device according to claim 8, wherein the amplification circuit further includes a step-down voltage divider circuit, wherein the step-down voltage divider circuit has a positive voltage divider resistor, a negative voltage divider resistor and a DC blocking capacitor, wherein one end of the negative voltage divider resistor is connected to a negative DC power supply voltage, the other end of the negative voltage divider resistor is connected to a positive DC power supply voltage via the positive voltage divider resistor, and is electrically connected to the signal output terminal of the pyroelectric infrared sensor via the DC blocking capacitor, wherein the operational amplifier OP1 is electrically connected at its inverting input terminal between the positive voltage divider resistor and the negative voltage divider resistor via the first series RC circuit.

12. The passive infrared detection device according to claim 11, wherein the non-inverting input terminal of the operational amplifier OP1 is grounded.

13. The passive infrared detection device according to any one of claims 1 to 3, wherein the amplification circuit uses an inverting negative feedback amplification circuit as the secondary amplification circuit, and the secondary amplification circuit has an operational amplifier OP2, a feedback resistor R2 and a second series RC circuit, wherein the output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R2, and the inverting input terminal of the operational amplifier OP2 is electrically connected to the output terminal of the operational amplifier OP1 through the second series RC circuit to receive the detection signal amplified by the primary amplification circuit.

14. The passive infrared detection device according to claim 13, wherein a DC bias voltage Vref2 is connected to the non-inverting input terminal of the operational amplifier OP2, and the DC bias voltage Vref2 connected to the non-inverting input terminal of the operational amplifier OP2 is set to be similar to the DC bias voltage Vref1 connected to the non-inverting input terminal of the operational amplifier OP1 within a difference range of less than or equal to 0.5V.

15. The passive infrared detection device according to claim 13, wherein the amplification circuit is configured to provide the DC bias voltage Vref2 to the non-inverting input terminal of the operational amplifier OP2 of the secondary amplification circuit via a second voltage divider circuit, wherein the second voltage divider circuit has a second voltage divider resistor and a second ground resistor, wherein one end of the second ground resistor is grounded, and the other end of the second ground resistor is connected to the DC power supply voltage via the second voltage divider resistor, and the non-inverting input terminal of the operational amplifier OP2 of the secondary amplification circuit is electrically connected between the second voltage divider resistor and the second ground resistor.

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