Passive infrared detection device that can shorten power-on time

Abstract

This invention provides a passive infrared detection device that can shorten power-on time. The passive infrared detection device includes a pyroelectric infrared sensor and an amplifier circuit. The amplifier circuit uses a non-inverting negative feedback amplifier circuit powered by dual power supplies as the primary amplifier circuit. A step-down voltage divider circuit is configured to pull down the DC bias voltage of the detection signal output from the signal output terminal of the pyroelectric infrared sensor. In this way, at the beginning of power-on of the passive infrared detection device, there is a small voltage difference between the non-inverting and inverting input terminals of the operational amplifier of the primary amplifier circuit. This reduces the time required for the voltage between the non-inverting and inverting input terminals of the operational amplifier to become consistent during the charging and discharging process, thereby shortening the power-on time of the primary amplifier circuit.

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 decreases 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 that can shorten power-on time. The amplification circuit uses a dual-power-supply in-phase negative feedback amplification circuit as the primary amplification circuit, and is configured with a step-down voltage divider circuit to pull down the DC bias voltage of the detection signal output from the pyroelectric infrared sensor. The primary amplification circuit includes an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. The operational amplifier OP1 is configured to use a dual-power supply. The inverting input terminal of the operational amplifier OP1 is connected to the output terminal of the operational amplifier OP1 via the feedback resistor R1, and to the output terminal of the operational amplifier OP1 via a series connection. The resistor R2 and the capacitor C1 are grounded. The non-inverting input of the operational amplifier OP1 is electrically connected to the signal output of the pyroelectric infrared sensor to receive the detection signal after the DC bias voltage is pulled low. In this way, the voltage difference between the non-inverting and inverting inputs of the operational amplifier OP1 can be reduced at the beginning of the power-on of the passive infrared detection device, so that the output of the operational amplifier OP1 can quickly stabilize. This can shorten the power-on time of the amplifier circuit. Correspondingly, when the high-pass cutoff frequency of the amplifier circuit is lower than 0.3Hz, the problem of excessively long power-on time caused by the low high-pass cutoff frequency of the amplifier circuit is solved.

[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, leading to a prolonged power-on period. This is one reason 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 for their amplifier circuits. However, when the operational amplifier OP1 is set to a dual-power supply state, and the DC bias voltage of the detection signal output from the pyroelectric infrared sensor is lowered by the step-down voltage divider circuit, the DC bias voltage of the detection signal connected to the non-inverting input of the operational amplifier OP1 is reduced. Consequently, the voltage difference between the non-inverting and inverting inputs of the operational amplifier OP1 is reduced at the initial power-on of the passive infrared detection device, allowing the output of the operational amplifier OP1 to quickly stabilize, thus shortening the power-on time of the amplifier circuit. This 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, this utility model provides a passive infrared detection device capable of shortening power-on time, the passive infrared detection device comprising:

[0013] A pyroelectric infrared sensor; and

[0014] An amplifier circuit is provided, wherein the primary amplifier circuit is a non-inverting negative feedback amplifier circuit powered by dual power supplies, and a step-down voltage divider circuit is configured to pull down the DC bias voltage of the detection signal output from the signal output terminal of the pyroelectric infrared sensor. The primary amplifier circuit includes an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. The operational amplifier OP1 is powered by dual power supplies, and its inverting input terminal is connected to its output terminal via the feedback resistor R1. The resistor R2 and capacitor C1, connected in series, are grounded. The non-inverting input of the operational amplifier OP1 is electrically connected to the signal output of the pyroelectric infrared sensor to receive the detection signal after the DC bias voltage is pulled low. In this way, at the beginning of the power-on of the passive infrared detection device, there is a small voltage difference between the non-inverting and inverting inputs of the operational amplifier OP1, which reduces the time required for the voltage between the non-inverting and inverting inputs of the operational amplifier OP1 to become consistent during the charging and discharging process, thereby shortening the power-on time of the primary amplifier circuit.

[0015] In one embodiment, the step-down voltage divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the non-inverting input terminal of the operational amplifier OP1 is connected to a negative DC power supply voltage via the voltage divider resistor and electrically connected to the signal output terminal of the pyroelectric infrared sensor via the voltage matching resistor.

[0016] In one embodiment, the voltage matching resistor is further connected in parallel with a capacitor.

[0017] In one embodiment, based on the matching setting of the pyroelectric infrared sensor's own impedance and the step-down voltage divider circuit, the voltage at one end of the voltage matching resistor electrically connected to the pyroelectric infrared sensor corresponds to the state of the original DC bias voltage of the detection signal output by the pyroelectric infrared sensor, while the voltage at the other end of the voltage matching resistor is pulled down to ground potential.

[0018] In one embodiment, the step-down voltage divider circuit includes a positive voltage divider resistor, a negative voltage divider resistor, and a DC blocking capacitor. 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. The operational amplifier OP1 is electrically connected at its non-inverting input terminal between the positive voltage divider resistor and the negative voltage divider resistor.

[0019] In one embodiment, the DC bias voltage of the probe signal connected to the non-inverting input of the operational amplifier OP1 is pulled down to ground potential based on the ratio between the positive voltage divider resistor and the negative voltage divider resistor.

[0020] In one embodiment, the primary amplifier circuit is configured to have a high-pass cutoff frequency of less than 0.3 Hz.

[0021] In one embodiment, the amplification circuit uses a dual-powered inverting negative feedback amplification circuit as the secondary amplification circuit. The secondary amplification circuit includes an operational amplifier OP2, a feedback resistor R3, and a series RC circuit. The operational amplifier OP2 is configured to be powered by a dual power supply. The inverting input terminal of the operational amplifier OP2 is connected to the output terminal of the operational amplifier OP2 via the feedback resistor R3, and electrically connected to the output terminal of the operational amplifier OP1 via the series RC circuit to receive the detection signal amplified by the primary amplification circuit.

[0022] In one embodiment, the non-inverting input of operational amplifier OP2 is grounded.

[0023] In one embodiment, the operational amplifier OP1 of the primary amplifier circuit and the operational amplifier OP2 of the secondary amplifier circuit are integrated on the same chip.

[0024] The further objectives and advantages of this invention will become fully apparent from the following description and accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the principle of passive infrared detection technology.

[0026] 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.

[0027] 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.

[0028] Figure 4 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

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Specifically, in this embodiment of the present invention, the amplification circuit 30 uses a non-inverting negative feedback amplification circuit powered by dual power supplies as the primary amplification circuit 31, and is configured to use a step-down voltage divider circuit 32 to pull down the DC bias voltage of the detection signal output from the signal output terminal of the pyroelectric infrared sensor 20. Correspondingly, the primary amplification circuit 31 is configured to have a high-pass cutoff frequency of less than 0.3Hz, and the detection signal after the DC bias voltage is pulled down is connected.

[0046] Corresponding to the state where the amplification circuit 30 is a primary amplification circuit 31 with a dual-power supply and non-inverting negative feedback amplification circuit, the primary amplification circuit 31 has an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. The operational amplifier OP1 is configured to be powered by a dual power supply. The inverting input terminal of the operational amplifier OP1 is connected to the output terminal of the operational amplifier OP1 via the feedback resistor R1, and grounded via the series-connected resistor R2 and capacitor C1. The non-inverting input terminal of the operational amplifier OP1 is electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 to input DC bias. The detection signal after the voltage is pulled low can reduce the voltage difference between the non-inverting and inverting input terminals of the operational amplifier OP1 at the beginning of the power-on of the passive infrared detection device. This allows the output of the operational amplifier OP1 to stabilize quickly. Therefore, when the power-on time is used to describe the time from power-on to the stable amplification and output of the input signal, the power-on time of the amplifier circuit can be shortened. Correspondingly, when the high-pass cutoff frequency of the amplifier circuit is lower than 0.3Hz, the problem of excessively long power-on time caused by the low high-pass cutoff frequency of the amplifier circuit is solved.

[0047] In other words, the amplification circuit 30 uses a non-inverting negative feedback amplification circuit powered by dual power supplies as the primary amplification circuit 31, and is configured to use the step-down voltage divider circuit 32 to pull down the DC bias voltage of the detection signal output from the signal output terminal of the pyroelectric infrared sensor 20. This results in the detection signal connected to the primary amplification circuit 31 being a detection signal with the DC bias voltage pulled down. Thus, at the beginning of the power-on of the passive infrared detection device, there is a small voltage difference between the non-inverting and inverting input terminals of the operational amplifier OP1 in the primary amplification circuit 31. This reduces the time required for the voltage between the non-inverting and inverting input terminals of the operational amplifier OP1 to become consistent during the charging and discharging process, thereby shortening the power-on time of the primary amplification circuit 31. Therefore, without changing the amplification factor and high-pass cutoff frequency of the primary amplification circuit 31, the output of the operational amplifier OP1 can quickly stabilize, thus shortening the power-on time of the amplification circuit 30.

[0048] It is understood that the buck-divider circuit 32 is configured to lower the DC bias voltage of the detection signal connected to the non-inverting input of the operational amplifier OP1 (which uses a dual-power supply) at the initial power-on of the passive infrared detection device, based on the need to reduce the voltage difference between the non-inverting and inverting inputs of the operational amplifier OP1. For example, it lowers the DC bias voltage of the detection signal connected to the non-inverting input of the operational amplifier OP1 (which uses a dual-power supply) to ground potential, thereby reducing the time required for the voltage between the non-inverting and inverting inputs of the operational amplifier OP1 to become consistent during the charging and discharging process, and thus shortening the power-on time of the primary amplifier circuit 31. The specific circuit configuration of the buck-divider circuit 32 can vary depending on the purpose of lowering the DC bias voltage of the detection signal connected to the non-inverting input of the operational amplifier OP1 (which uses a dual-power supply), and this invention does not limit this.

[0049] For example, in this embodiment of the present invention, the step-down voltage divider circuit 32 has a voltage divider resistor 321 and a voltage matching resistor 322. The non-inverting input terminal of the operational amplifier OP1 is connected to a negative DC power supply voltage via the voltage divider resistor 321 and electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via the voltage matching resistor 322. 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 32, the voltage at one end of the voltage matching resistor 322 electrically connected to the pyroelectric infrared sensor 20 corresponds to the state of the original DC bias voltage of the detection signal output by the pyroelectric infrared sensor 20. This allows the voltage at the other end of the voltage matching resistor 322 to be pulled down, for example, to ground potential. At the beginning of the power-on of the passive infrared detection device, the voltage between the non-inverting and inverting input terminals of the operational amplifier OP1 tends to be consistent, which in turn allows the output of the operational amplifier OP1 to quickly stabilize and shortens the power-on time of the amplifier circuit 30.

[0050] It is worth mentioning that, in order 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 original DC bias voltage of the detection signal output by the pyroelectric infrared sensor 20, and that the voltage at the other end of the voltage matching resistor 322 can be pulled down to the target value and remain stable, high requirements are placed on the resistance accuracy and stability of the voltage matching resistor 322. Therefore, when the resistance value of the voltage matching resistor 322 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 non-inverting input of the operational amplifier OP1. In view of this, in another embodiment of the present invention, the amplification circuit 30 can also correspond to... Figure 3 exist Figure 2 Based on the structure of the amplifier circuit 30 shown, a capacitor is further connected in parallel with the voltage matching resistor 322. By connecting the capacitor in parallel with the voltage matching resistor 322, when the resistance value of the voltage matching resistor 322 in actual use deviates or is affected by environmental factors, the impedance matching is optimized to avoid signal attenuation problems.

[0051] As a further example, in another embodiment of this utility model, another circuit configuration of the step-down voltage divider circuit 32A is... Figure 4 The diagram illustrates that the step-down voltage divider circuit 32A includes a positive voltage divider resistor 321A, a negative voltage divider resistor 322A, and a DC blocking capacitor 323A. One end of the negative voltage divider resistor 322A is connected to a negative DC power supply voltage, and the other end of the negative voltage divider resistor 322A is connected to a positive DC power supply voltage via the positive voltage divider resistor 321A and electrically connected to the signal output terminal of the pyroelectric infrared sensor 20 via the DC blocking capacitor 323A. The operational amplifier OP1 is electrically connected at its non-inverting input terminal between the positive voltage divider resistor 321A and the negative voltage divider resistor 322A. This allows the operational amplifier OP1 to both input the AC component of the detection signal output from the pyroelectric infrared sensor 20 at its non-inverting input terminal and, based on the ratio between the positive voltage divider resistor 321A and the negative voltage divider resistor 322A, pull down the DC bias voltage of the detection signal input at its non-inverting input terminal. For example, by pulling the voltage down to ground potential at the initial power-on of the passive infrared detection device, the voltage between the non-inverting and inverting input terminals of the operational amplifier OP1 tends to be consistent, thereby enabling the output of the operational amplifier OP1 to quickly stabilize and shortening the power-on time of the amplifier circuit 30.

[0052] Specifically, in the above embodiments of this utility model, the secondary amplifier circuit 33 of the amplifier circuit 30 is exemplarily shown as an inverting negative feedback amplifier circuit with dual power supply. The secondary amplifier circuit 33 has an operational amplifier OP2, a feedback resistor R3, and a series RC circuit. The operational amplifier OP2 is configured to be powered by dual power supply. The inverting input terminal of the operational amplifier OP2 is connected to the output terminal of the operational amplifier OP2 via the feedback resistor R3 and electrically connected to the output terminal of the operational amplifier OP1 via the series RC circuit to receive the detection signal amplified by the primary amplifier circuit 31. The non-inverting input terminal of the operational amplifier OP2 is connected to a DC bias voltage Vref, thus forming an inverting negative feedback amplifier circuit.

[0053] It is understandable that, since 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 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 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 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 series RC circuit can quickly stabilize. Thus, when the DC bias voltage Vref is set to be similar to the DC bias voltage connected to the non-inverting input of the operational amplifier OP1, the voltage difference between the non-inverting and inverting inputs of the operational amplifier OP2 can be reduced simultaneously, thereby further shortening the power-on time of the amplifier circuit 30.

[0054] In these embodiments of the present invention, based on the requirement to reduce the voltage difference between the non-inverting and inverting input terminals of the operational amplifier OP1, the DC bias voltage of the detection signal connected to the non-inverting input terminal of the operational amplifier OP1 is preferably pulled down to ground potential, and the non-inverting input terminal of the operational amplifier OP2 is preferably grounded so that the DC bias voltage Vref connected to the non-inverting input terminal of the operational amplifier OP2 also corresponds to ground potential, thereby synchronously reducing the voltage difference between the non-inverting and inverting input terminals of the operational amplifier OP2.

[0055] Specifically, in the above embodiments of this utility model, the secondary amplifier circuit 33 is configured as an inverting negative feedback amplifier circuit powered by dual power supplies only as an example to demonstrate the influence of the power-on time of the primary amplifier circuit 31 on the power-on time of the amplifier circuit 30. When the DC bias voltage of the probe signal connected to the non-inverting input terminal of the operational amplifier OP1 of the primary amplifier circuit 31 is pulled low based on the configuration of the buck divider circuit 32, the power-on time of the amplifier circuit 30 can be shortened based on the shortening of the power-on time of the primary amplifier circuit 31. Therefore, the specific circuit configuration of the secondary amplifier circuit 33 does not constitute a limitation on this utility model.

[0056] In other words, in the passive infrared detection device of this utility model, when the amplification circuit 30 is an amplification circuit with no less than two amplification stages and includes at least one secondary amplification circuit 33, the specific form of the secondary amplification circuit 33 does not constitute a limitation on this utility model.

[0057] It is understood that when the DC bias voltage of the detection signal connected to the non-inverting input terminal of the operational amplifier OP1 in the primary amplifier circuit 31 is pulled low based on the setting of the buck divider circuit 32, the power-on time of the amplifier circuit 30 can be shortened by reducing the power-on time of the primary amplifier circuit 31. In other words, by lowering the DC bias voltage of the detection signal connected to the non-inverting input terminal of the operational amplifier OP1 in the primary amplifier circuit 31, the reduction in the power-on time of the primary amplifier circuit 31 is not limited by the high-pass cutoff frequency of the primary amplifier circuit 31. Therefore, 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.

[0058] Furthermore, in the above embodiments of this utility model, the inverting input terminal of the amplifier OP1 is specifically connected to one end of the capacitor C1 via the resistor R2, while the other end of the capacitor C1 is grounded. This forms a structural feature where the inverting input terminal of the operational amplifier OP1 is grounded via the series-connected resistor R2 and capacitor C1. The relative positional relationship between the series-connected resistor R2 and capacitor C1 does 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 connected to one end of the resistor R2 via the capacitor C1, while the other end of the resistor R2 is grounded.

[0059] Furthermore, those skilled in the art should understand that the voltage / potential descriptions in the above and following descriptions of this utility model are descriptions of the corresponding voltage / potential of the passive infrared detection device and the amplification circuit 30 in the powered-on state. They are only used to understand and describe the working principle of the passive infrared detection device and the amplification circuit 30 of this utility model, and do not constitute a limitation on whether the passive infrared detection device and the amplification circuit 30 are in the powered-on state.

[0060] 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 32 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 non-inverting / 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. Furthermore, a capacitor can 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.

[0061] 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.

[0062] 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 a non-inverting negative feedback amplifier circuit powered by dual power supplies, and a step-down voltage divider circuit is configured to pull down the DC bias voltage of the detection signal output from the signal output terminal of the pyroelectric infrared sensor. The primary amplifier circuit includes an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. The operational amplifier OP1 is powered by dual power supplies, and its inverting input terminal is connected to its output terminal via the feedback resistor R1. The resistor R2 and capacitor C1, connected in series, are grounded. The non-inverting input of the operational amplifier OP1 is electrically connected to the signal output of the pyroelectric infrared sensor to receive the detection signal after the DC bias voltage is pulled low. In this way, at the beginning of the power-on of the passive infrared detection device, there is a small voltage difference between the non-inverting and inverting inputs of the operational amplifier OP1, which reduces the time required for the voltage between the non-inverting and inverting inputs of the operational amplifier OP1 to become consistent during the charging and discharging process, thereby shortening the power-on time of the primary amplifier circuit.

2. The passive infrared detection device according to claim 1, wherein the step-down voltage divider circuit has a voltage divider resistor and a voltage matching resistor, wherein the non-inverting input terminal of the operational amplifier OP1 is connected to a negative DC power supply voltage through the voltage divider resistor and electrically connected to the signal output terminal of the pyroelectric infrared sensor through the voltage matching resistor.

3. The passive infrared detection device according to claim 2, wherein the voltage matching resistor is further connected in parallel with a capacitor.

4. The passive infrared detection device according to claim 2, wherein, based on the matching setting of the self-impedance of the pyroelectric infrared sensor and the step-down voltage divider circuit, when the voltage at one end of the voltage matching resistor electrically connected to the pyroelectric infrared sensor corresponds to the original DC bias voltage of the detection signal output by the pyroelectric infrared sensor, the voltage at the other end of the voltage matching resistor is pulled down to ground potential.

5. The passive infrared detection device according to claim 1, 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 non-inverting input terminal between the positive voltage divider resistor and the negative voltage divider resistor.

6. The passive infrared detection device according to claim 5, wherein the DC bias voltage of the detection signal connected to the non-inverting input terminal of the operational amplifier OP1 is pulled down to ground potential based on the ratio between the positive voltage divider resistor and the negative voltage divider resistor.

7. The passive infrared detection device according to any one of claims 1 to 6, wherein the primary amplifier circuit is configured to have a high-pass cutoff frequency of less than 0.3 Hz.

8. The passive infrared detection device according to claim 7, wherein the amplification circuit uses an inverting negative feedback amplification circuit powered by dual power supplies as the secondary amplification circuit, and the secondary amplification circuit has an operational amplifier OP2, a feedback resistor R3 and a series RC circuit, wherein the operational amplifier OP2 is configured to be powered by dual power supplies, and the inverting input terminal of the operational amplifier OP2 is connected to the output terminal of the operational amplifier OP2 via the feedback resistor R3, and electrically connected to the output terminal of the operational amplifier OP1 via the series RC circuit to receive the detection signal amplified by the primary amplification circuit.

9. The passive infrared detection device according to claim 8, wherein the non-inverting input terminal of the operational amplifier OP2 is grounded.

10. The passive infrared detection device according to claim 8, wherein the operational amplifier OP1 of the primary amplifier circuit and the operational amplifier OP2 of the secondary amplifier circuit are integrated on the same chip.

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