Passive infrared detection device and amplifying circuit capable of shortening power-on time thereof

Abstract

The invention provides a passive infrared detection device and an amplification circuit capable of shortening power-on time thereof, the passive infrared detection device utilizes the characteristic that a detection signal output by a pyroelectric infrared sensor has an integral characteristic (charge accumulation is generated by temperature change), and the passive infrared detection device is correspondingly applied to a long-distance detection application scene. The temperature change corresponding to the trans-regional movement of the human body can generate a slow change component close to direct current in the detection signal based on the accumulated change of charges, and then an unexpected slow change signal lower than 0.3 Hz is generated in the detection signal, and the slow change signal lower than 0.3 Hz in the detection signal is used as an effective signal. According to the human body cross-region motion detection circuit, long-distance human body cross-region motion detection is achieved, and the problem that the power-on time is too long due to the fact that the high-pass cut-off frequency of the amplifying circuit is too low is solved on the basis of improvement of the amplifying circuit in the state that the frequency lower than 0.3 Hz is the high-pass cut-off frequency of the amplifying circuit.

Description

Technical Field

[0001] The present invention relates to the field of infrared detection, and more particularly to a passive infrared detection device and an amplifier circuit capable of shortening the power-on time. Background Art

[0002] With the development of Internet of Things technology and the popularization of the concept of low-carbon environmental protection, the demand for environmental detection, especially for human movement detection, in artificial intelligence, smart home, and intelligent security technologies is increasing. The working state of electrical equipment is intelligently controlled based on the detection result of whether a human body exists, such as intelligently controlling the lighting state of a lamp based on the detection result of whether a human body exists to achieve intelligent low-carbon lighting.

[0003] Passive infrared detection technology is a relatively mature human presence detection technology among existing human presence detection technologies. Its detection principle is based on the partitioning of a corresponding detection area by a multi-window lens and the detection of cross-region movements of a human body in the detection area by a pyroelectric infrared sensor (PIR). The passive infrared detection technology has the advantages of low cost and the ability to accurately set the detection angle based on the structural design of the multi-window lens, and does not infringe on human privacy, so it has become the most commonly used human presence detection technology at present. In terms of the detection principle of passive infrared detection technology, it is generally considered that as the detection distance increases, since the detected human body is relatively far from the infrared detection device using passive infrared detection technology, on the one hand, it will lead to a decrease in the amount of infrared light captured by the pyroelectric infrared sensor from the detected human body, thereby reducing the intensity of the effective signal related to the cross-region movement of the human body in the detection signal; on the other hand, it will also make the areas of each partition in the detection area large and scattered, that is, the number of partitions per unit area decreases, reducing the resolution of the infrared detection device.

[0004] Therefore, in the product design concept of existing infrared detection devices, for the purpose of increasing distance detection, it is usually necessary to increase the window area in the multi-window lens to ensure the signal strength in the detection signal related to the cross-region movement of the human body, and increase the number of windows in the multi-window lens to ensure the resolution of the infrared detection device. In the signal processing rule of the detection signal, based on the empirical knowledge of the frequency components of the effective signal corresponding to the cross-region movement of the human body in the detection signal, it is considered that the energy of the actual effective signal is concentrated in 0.3 Hz to 10 Hz, and the energy proportion of the effective signal below 0.3 Hz is extremely low, and it decreases in intensity as the detection distance increases. When the high-pass cut-off frequency of the amplifier circuit of the infrared detection device is set at a frequency less than 0.3 Hz, it will neither increase the energy proportion of the effective signal nor may cause a baseline drift risk due to the high-pass cut-off frequency approaching the DC component. Therefore, the high-pass cut-off frequency of the amplifier circuit of the infrared detection device is usually set at a frequency greater than or equal to 0.3 Hz. However, under the reasonable product size limitation and the trend of product miniaturization, since the window area and the number of windows of the multi-window lens cannot be increased simultaneously, even if an infrared detection device with a multi-window lens with a diameter of up to 80 mm is used, its maximum detection distance is difficult to exceed 12 meters under the signal processing rule of the aforementioned detection signal. Summary of the Invention

[0005] An object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time thereof, wherein the passive infrared detection device can reduce the requirements for the window area and the number of windows of the multi-window lens when applied to long-distance detection, which is correspondingly beneficial to realizing long-distance detection applications with a smaller size of the multi-window lens, and thus is suitable for the trend of miniaturized products.

[0006] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time thereof. The passive infrared detection device utilizes the characteristic that the detection signal output by the pyroelectric infrared sensor has an integration characteristic (temperature change generates charge accumulation). In the application scenario of long-distance detection, the temperature change corresponding to the cross-region movement of the human body can generate a slow-changing component close to DC in the detection signal based on the cumulative change of charges, and further generate an unexpected slow-changing signal below 0.3 Hz in the detection signal. By using the slow-changing signal below 0.3 Hz in the detection signal as an effective signal, the detection of the cross-region movement of the human body at a long distance is realized.

[0007] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time, wherein the detection signal output by the pyroelectric infrared sensor has an integration characteristic, and the slow-changing signal below 0.3 Hz generated in the detection signal based on this characteristic of the pyroelectric infrared sensor is different in generation mode from the effective signal. Therefore, this slow-changing signal is usually regarded as an unexpected interference change. The passive infrared detection device of the present invention utilizes the corresponding relationship between this slow-changing signal and the cross-region movement of the human body in the long-distance detection application scenario, and uses the slow-changing signal below 0.3 Hz in the detection signal as the effective signal to detect the cross-region movement of the human body at a long distance. Therefore, it can ensure the energy ratio of the effective signal in the detection signal based on the integration characteristic of the detection signal output by the pyroelectric infrared sensor, and because the signal usually regarded as an unexpected interference change is used as the effective signal, it can reduce the energy ratio of the interference signal in the detection signal.

[0008] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time, wherein the passive infrared detection device utilizes the integration characteristic of the detection signal output by the pyroelectric infrared sensor, and realizes the detection of the cross-region movement of the human body at a long distance by using the unexpected slow-changing signal below 0.3 Hz generated in the detection signal based on this characteristic as the effective signal. Therefore, it can ensure the energy ratio of the effective signal in the detection signal based on the integration characteristic of the detection signal output by the pyroelectric infrared sensor, thereby reducing the requirements for the window area and the number of windows of the multi-window lens, and correspondingly facilitating the realization of long-distance detection applications with a smaller size of the multi-window lens and adapting to the trend of miniaturized products.

[0009] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time, wherein the amplifier circuit is electrically connected to the pyroelectric infrared sensor to amplify the AC component of the detection signal output by the pyroelectric infrared sensor, and is set to have a high-pass cut-off frequency below 0.3 Hz, so that the slow-changing signal generated based on the aforementioned integration characteristic in the detection signal can be retained and amplified as an effective signal.

[0010] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit capable of shortening the power-on time, wherein the amplifier circuit uses an in-phase negative feedback amplifier circuit as the primary amplifier circuit, and utilizes the electrical characteristics of the in-phase negative feedback amplifier circuit having a high input impedance and a low output impedance to enable the amplifier circuit to amplify the slow-changing signal generated based on the aforementioned integration characteristic in the detection signal with a stable amplification factor.

[0011] Another object of the present invention is to provide a passive infrared detection device and an amplifying circuit thereof capable of shortening the power-on time. The amplifying circuit uses a non-inverting negative feedback amplifying circuit as the primary amplifying circuit. Corresponding to the primary amplifying circuit, there is an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor to access the detection signal output from the pyroelectric infrared sensor. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other, so as to form a non-inverting negative feedback amplifying circuit with the amplification factor related to R1 / R2 and the high-pass cut-off frequency related to R2C1.

[0012] Another object of the present invention is to provide a passive infrared detection device and an amplifying circuit thereof capable of shortening the power-on time. Different from the traditional non-inverting negative feedback amplifying circuit that directly grounds the resistor R2 and the capacitor C1 connected in series with each other to keep the inverting input terminal of the operational amplifier OP1 grounded for AC, in the primary amplifying circuit of the amplifying circuit of the present invention, a DC bias voltage Vref1 is further connected to the end of the resistor R2 and the capacitor C1 connected in series with each other that is grounded for AC. The difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5V and tends to be the same. Thus, at the beginning of power-on of the passive infrared detection device, the voltages of the non-inverting input terminal and the inverting input terminal of the operational amplifier OP1 can approach each other, so that the output of the output terminal of the operational amplifier OP1 can quickly tend to be stable. Therefore, the power-on time of the amplifying circuit can be shortened. Correspondingly, when the high-pass cut-off frequency of the amplifying circuit is lower than 0.3Hz, the problem of too long power-on time caused by too low high-pass cut-off frequency of the amplifying circuit can be solved.

[0013] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit thereof capable of shortening the power-on time. When the high-pass cut-off frequency of the amplifier circuit is below 0.3 Hz, the too low high-pass cut-off frequency of the amplifier circuit will increase the power-on time of the amplifier circuit, resulting in the problem of too long power-on time of the amplifier circuit. This is also one of the reasons why the existing infrared detection devices in practical applications usually use a frequency greater than or equal to 0.3 Hz as the high-pass cut-off frequency of the corresponding amplifier circuit. When the mutually series-connected resistor R2 and capacitor C1 are further connected to the DC bias voltage Vref1 at the end that is grounded for AC, and the connected DC bias voltage Vref1 is set to be approximately the same as the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 within a difference range of less than or equal to 0.5 V, even when the high-pass cut-off frequency of the amplifier circuit is below 0.3 Hz, the power-on time of the amplifier circuit can be shortened to be shorter than that of the existing infrared detection device when the high-pass cut-off frequency of the corresponding amplifier circuit is greater than or equal to 0.3 Hz. Therefore, it is beneficial to the commercial application and popularization of the passive infrared detection device and has important commercial value.

[0014] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit thereof capable of shortening the power-on time. The amplifier circuit is provided with a voltage dividing circuit to provide the DC bias voltage Vref1 for the mutually series-connected resistor R2 and capacitor C1. The voltage dividing circuit has a voltage dividing resistor and a resistor to ground. One end of the resistor to ground is grounded, and the other end of the resistor to ground is connected to the DC power supply voltage through the voltage dividing resistor. The end of the mutually series-connected resistor R2 and capacitor C1 connected to the DC bias voltage Vref1 is electrically connected between the voltage dividing resistor and the resistor to ground, so that this end of the mutually series-connected resistor R2 and capacitor C1 can be grounded for AC and can be connected to the DC bias voltage Vref1 related to the ratio between the voltage dividing resistor and the resistor to ground when the resistor to ground is connected to the DC power supply voltage through the voltage dividing resistor. Therefore, it is simple and easy to implement.

[0015] Another object of the present invention is to provide a passive infrared detection device and an amplifier circuit thereof capable of shortening the power-on time. The resistor to ground of the voltage dividing circuit is electrically connected to the power supply terminal of the pyroelectric infrared sensor through the voltage dividing resistor, so as to avoid connecting an additional power supply. Therefore, the structure of connecting the mutually series-connected resistor R2 and capacitor C1 to the DC bias voltage Vref1 can be simplified and the cost of connecting the mutually series-connected resistor R2 and capacitor C1 to the DC bias voltage Vref1 can be reduced.

[0016] To achieve at least one of the above objects, according to one aspect of the present invention, the present invention provides a passive infrared detection device, and the passive infrared detection device includes:

[0017] A multi-window lens;

[0018] A pyroelectric infrared sensor, wherein a partition is formed on the photosensitive surface of the pyroelectric infrared sensor through the window of the multi-window lens; and

[0019] An amplifying circuit, wherein the amplifying circuit is electrically connected to the pyroelectric infrared sensor to amplify the AC component of the detection signal output by the pyroelectric infrared sensor, and is set to have a high-pass cut-off frequency lower than 0.3 Hz, so that the slowly varying signal in the detection signal whose change period is close to the time when a human body passes through the partition 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.

[0020] In one embodiment, the amplifying circuit uses an in-phase negative feedback amplifying circuit as the primary amplifying circuit. The primary amplifying circuit is set to have a high-pass cut-off frequency lower than 0.3 Hz, and has an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor to access the detection signal output from the pyroelectric infrared sensor. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other.

[0021] In one embodiment, a DC bias voltage Vref1 is further connected to the end of the resistor R2 and the capacitor C1 connected in series that is grounded for AC. The difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5 V and tends to be the same.

[0022] In one embodiment, the amplifier circuit is arranged to provide the DC bias voltage Vref1 for the mutually series-connected resistor R2 and capacitor C1 through a first voltage-dividing circuit. The first voltage-dividing circuit has a first voltage-dividing 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 power supply voltage through the first voltage-dividing resistor. The end of the mutually series-connected resistor R2 and capacitor C1 for accessing the DC bias voltage Vref1 is electrically connected between the first voltage-dividing resistor and the first resistor to ground, so that this end of the mutually series-connected resistor R2 and capacitor C1 can be grounded for AC and can access the DC bias voltage Vref1 related to the ratio between the first voltage-dividing resistor and the first resistor to ground when the first resistor to ground is connected to the DC power supply voltage through the first voltage-dividing resistor.

[0023] In one embodiment, the first resistor to ground of the first voltage-dividing circuit is electrically connected to the power supply terminal of the pyroelectric infrared sensor through the first voltage-dividing resistor to access the DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0024] In one embodiment, the operational amplifier OP1 is arranged to be powered in a single power supply mode.

[0025] In one embodiment, the amplifier circuit further includes a DC-blocking voltage-dividing circuit. The DC-blocking voltage-dividing circuit has a voltage-dividing resistor, a resistor to ground, and a DC-blocking capacitor. One end of the resistor to ground is grounded, the other end of the resistor to ground is connected to the DC power supply voltage through the voltage-dividing resistor, and is electrically connected to the pyroelectric infrared sensor through the DC-blocking capacitor. The non-inverting input terminal of the operational amplifier OP1 is electrically connected between the voltage-dividing resistor and the resistor to ground.

[0026] In one embodiment, the resistor to ground is connected to the power supply terminal of the pyroelectric infrared sensor through the voltage-dividing resistor to access the DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0027] In one embodiment, the amplifier circuit further includes a third voltage-dividing circuit. The third voltage-dividing circuit has a third voltage-dividing resistor and a voltage matching resistor. The non-inverting input terminal of the operational amplifier OP1 is connected to the DC power supply voltage through the third voltage-dividing resistor and is electrically connected to the pyroelectric infrared sensor through the voltage matching resistor.

[0028] In one embodiment, the non-inverting input terminal of the operational amplifier OP1 is connected to the power supply terminal of the pyroelectric infrared sensor through the third voltage-dividing resistor to access the DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0029] In one embodiment, a capacitor is further connected in parallel to the voltage matching resistor of the third voltage dividing circuit.

[0030] In one embodiment, the operational amplifier OP1 is powered in a dual-power supply manner.

[0031] In one embodiment, the amplifying circuit further includes a secondary amplifying circuit and a series RC circuit disposed between the primary amplifying circuit and the secondary amplifying circuit. The series RC circuit is equivalent to a capacitor and a resistor connected in series. The secondary amplifying circuit is an inverting negative feedback amplifying circuit and has an operational amplifier OP2 and a feedback resistor R3. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R3. One end of the series RC circuit is electrically connected to the output terminal of the primary amplifying circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2.

[0032] In one embodiment, the DC bias voltage Vref2 applied to the non-inverting input terminal of the operational amplifier OP2 is set to converge within a difference range less than or equal to 0.5V to the DC bias voltage Vrefin applied to the non-inverting input terminal of the operational amplifier OP1.

[0033] In one embodiment, the amplifying circuit is configured to provide the DC bias voltage Vref2 for the non-inverting input terminal of the operational amplifier OP2 through a second voltage dividing circuit. The second voltage dividing circuit has a second voltage dividing resistor and a second resistor to ground. One end of the second resistor to ground is grounded, and the other end is connected to the DC supply voltage through the second voltage dividing resistor. The non-inverting input terminal of the operational amplifier OP2 is electrically connected between the second voltage dividing resistor and the second resistor to ground, so as to access the DC bias voltage Vref2 related to the ratio between the second voltage dividing resistor and the second resistor to ground when the second resistor to ground is connected to the DC supply voltage through the second voltage dividing resistor.

[0034] In one embodiment, the amplifier circuit further includes a secondary amplifier circuit. The secondary amplifier circuit adopts a non-inverting negative feedback amplifier circuit and has an operational amplifier OP3, a feedback resistor R4, a resistor R5, and a capacitor C2. The output terminal of the operational amplifier OP3 is connected to the inverting input terminal of the operational amplifier OP3 through the feedback resistor R4. The non-inverting input terminal of the operational amplifier OP3 is electrically connected to the output terminal of the operational amplifier OP1 of the primary amplifier circuit 31. The inverting input terminal of the operational amplifier OP3 is further grounded for AC through the resistor R5 and the capacitor C2 connected in series with each other.

[0035] In one embodiment, a DC bias voltage Vref3 is further connected to one end of the resistor R5 and the capacitor C2 connected in series with each other that is grounded for AC. The difference between the DC bias voltage Vref3 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5V and tends to be the same.

[0036] In one embodiment, the DC bias voltage Vref3 is set to be the same as the DC bias voltage Vref1.

[0037] According to another aspect of the present invention, the present invention further provides an amplifier circuit capable of shortening the power-on time, which is used to amplify the AC component of the detection signal output by the pyroelectric infrared sensor. The amplifier circuit uses a non-inverting negative feedback amplifier circuit as the primary amplifier circuit. Corresponding to the primary amplifier circuit, there is an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor to access the detection signal output from the pyroelectric infrared sensor. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other and is connected to a DC bias voltage Vref1. The difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5V and tends to be the same.

[0038] In one embodiment, the amplifier circuit is arranged to provide the DC bias voltage Vref1 for the mutually series-connected resistor R2 and capacitor C1 through a first voltage dividing circuit. The first voltage dividing circuit has a first voltage dividing 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 through the first voltage dividing resistor. The end of the mutually series-connected resistor R2 and capacitor C1 that accesses the DC bias voltage Vref1 is electrically connected between the first voltage dividing resistor and the first resistor to ground, so that this end of the mutually series-connected resistor R2 and capacitor C1 can be grounded for AC and can access the DC bias voltage Vref1 related to the ratio between the first voltage dividing resistor and the first resistor to ground when the first resistor to ground is connected to the DC supply voltage through the first voltage dividing resistor.

[0039] In one embodiment, the first resistor to ground of the first voltage dividing circuit is electrically connected to the power supply terminal of the pyroelectric infrared sensor through the first voltage dividing resistor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0040] In one embodiment, the operational amplifier OP1 is arranged to be powered in a single power supply mode.

[0041] In one embodiment, the amplifier circuit further includes a DC blocking and voltage dividing circuit. The DC blocking and voltage dividing circuit has a voltage dividing resistor, a resistor to ground, and a DC blocking capacitor. One end of the resistor to ground is grounded, the other end of the resistor to ground is connected to the DC supply voltage through the voltage dividing resistor, and is electrically connected to the pyroelectric infrared sensor through the DC blocking capacitor. The non-inverting input terminal of the operational amplifier OP1 is electrically connected between the voltage dividing resistor and the resistor to ground.

[0042] In one embodiment, the resistor to ground is connected to the power supply terminal of the pyroelectric infrared sensor through the voltage dividing resistor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0043] In one embodiment, the amplifier circuit further includes a third voltage dividing circuit. The third voltage dividing circuit has a third voltage dividing resistor and a voltage matching resistor. The non-inverting input terminal of the operational amplifier OP1 is connected to the DC supply voltage through the third voltage dividing resistor and is electrically connected to the pyroelectric infrared sensor through the voltage matching resistor.

[0044] In one embodiment, the non-inverting input terminal of the operational amplifier OP1 is connected to the power supply terminal of the pyroelectric infrared sensor through the third voltage dividing resistor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

[0045] In one embodiment, a capacitor is further connected in parallel with the voltage matching resistor of the third voltage dividing circuit.

[0046] In one embodiment, the operational amplifier OP1 is powered in a dual - power - supply manner.

[0047] In one embodiment, the amplification circuit further includes a secondary amplification circuit and a series RC circuit disposed between the primary amplification circuit and the secondary amplification circuit. The series RC circuit is equivalent to a capacitor and a resistor connected in series. The secondary amplification circuit is an inverting negative - feedback amplification circuit and has an operational amplifier OP2 and a feedback resistor R3. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R3. One end of the series RC circuit is electrically connected to the output terminal of the primary amplification circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2.

[0048] In one embodiment, the DC bias voltage Vref2 applied to the non - inverting input terminal of the operational amplifier OP2 is set to converge within a difference range less than or equal to 0.5V to the DC bias voltage Vrefin applied to the non - inverting input terminal of the operational amplifier OP1.

[0049] In one embodiment, the amplification circuit is arranged such that a second voltage dividing circuit provides the DC bias voltage Vref2 for the non - inverting input terminal of the operational amplifier OP2. The second voltage dividing circuit has a second voltage dividing resistor and a second resistor to ground. One end of the second resistor to ground is grounded, and the other end is connected to the DC supply voltage through the second voltage dividing resistor. The non - inverting input terminal of the operational amplifier OP2 is electrically connected between the second voltage dividing resistor and the second resistor to ground, so as to access the DC bias voltage Vref2 related to the ratio between the second voltage dividing resistor and the second resistor to ground when the second resistor to ground is connected to the DC supply voltage through the second voltage dividing resistor.

[0050] In one embodiment, the amplifier circuit further includes a secondary amplifier circuit, where the secondary amplifier circuit uses a non-inverting negative feedback amplifier circuit and has an operational amplifier OP3, a feedback resistor R4, a resistor R5, and a capacitor C2. The output terminal of the operational amplifier OP3 is connected to the inverting input terminal of the operational amplifier OP3 through the feedback resistor R4. The non-inverting input terminal of the operational amplifier OP3 is electrically connected to the output terminal of the operational amplifier OP1 of the primary amplifier circuit 31. The inverting input terminal of the operational amplifier OP3 is further grounded for AC through the resistor R5 and the capacitor C2 connected in series with each other.

[0051] In one embodiment, a DC bias voltage Vref3 is further connected to one end of the resistor R5 and the capacitor C2 connected in series with each other that is grounded for AC. The difference between the DC bias voltage Vref3 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 tends to be the same within a range of less than or equal to 0.5V.

[0052] In one embodiment, the DC bias voltage Vref3 is set to be the same as the DC bias voltage Vref1.

[0053] Through the understanding of the following description and the drawings, the further objects and advantages of the present invention will be fully embodied. Description of the Drawings

[0054] Figure 1 It is a schematic diagram of the principle of passive infrared detection technology.

[0055] Figure 2A It is a schematic diagram of the circuit structure of a passive infrared detection device according to an embodiment of the present invention.

[0056] Figure 2B It is a schematic diagram of the corresponding voltage change of the circuit after the passive infrared detection device according to the above embodiment of the present invention is powered on.

[0057] Figure 3A It is a schematic diagram of the circuit structure of an existing infrared detection device.

[0058] Figure 3B It is a schematic diagram of the corresponding voltage change of the circuit after the existing infrared detection device is powered on.

[0059] Figure 4 It is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0060] Figure 5 It is a schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0061] Figure 6A Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0062] Figure 6B Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0063] Figure 7A Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0064] Figure 7B Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0065] Figure 8A Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention.

[0066] Figure 8B Schematic diagram of the circuit structure of a passive infrared detection device according to another embodiment of the present invention. Detailed implementation manners

[0067] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description of the present invention can be applied to other implementation manners, variations, improvements, equivalent solutions, and other technical solutions without departing from the spirit and scope of the present invention.

[0068] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0069] It can be 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, and in other embodiments, the number of the element can be multiple. The term "a" should not be construed as limiting the quantity.

[0070] For a full understanding of the present invention, refer to the accompanying drawings of the specification of the present invention Figure 1As shown, the principle of passive infrared detection technology is schematically illustrated. As mentioned above, the passive infrared detection technology is based on the partition of the corresponding detection area by the multi-window lens 10P, and the pyroelectric infrared sensor 20P detects the cross-region movement of the human body in the detection area. At least a pair of pyroelectric units 21P are arranged on the photosensitive surface of the pyroelectric infrared sensor 20P. A pair of the pyroelectric units 21P are two pyroelectric units 21P connected in series in opposite directions, so that a pair of the pyroelectric units 21P can cancel the environmental temperature drift and common-mode interference and be only sensitive to the dynamic temperature difference.

[0071] That is to say, in the partition formed by the window of the multi-window lens 10P on the photosensitive surface of the pyroelectric infrared sensor 20P, there are also a bright area and a dark area respectively corresponding to a pair of the pyroelectric units 21P, and a blind area is formed between the bright area and the dark area. Since a pair of the pyroelectric units 21P are two pyroelectric units 21P connected in series in opposite directions, the directions of the currents formed by the same temperature changes in the bright area and the dark area in the same partition are opposite and cancel each other out. Therefore, the overall temperature change of the partition corresponding to any window will not form a fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P. When the human body as a heat source passes through the partition corresponding to any window, the light spot formed by the heat source passing through the window on the photosensitive surface of the pyroelectric unit 21P will enter a pair of the pyroelectric units 21P successively as the human body moves, so that a dynamic temperature difference change can be generated between a pair of the pyroelectric units 21P and a fluctuating change can be formed in the detection signal output by the pyroelectric infrared sensor 20P.

[0072] It can be understood that based on the electrical characteristics of the pyroelectric unit 21P, even if there is a temperature difference between a pair of the pyroelectric units 21P, as long as the temperature difference does not change, the potential distribution between a pair of the pyroelectric units 21P tends to be balanced and will not form a fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P, that is, a pair of the pyroelectric units 21P are only sensitive to the dynamic temperature difference. The movement of the human body as a heat source inside the bright area or the dark area does not form a cross-region movement in theory and will not form a fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P. Therefore, when the human body as a heat source passes through the partition corresponding to any window, the fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P corresponds to the cross-region movement of the human body entering the bright area, the cross-region movement of the human body leaving the bright area, the cross-region movement of the human body entering the dark area, and the cross-region movement of the human body leaving the dark area. And when the fluctuation corresponding to the cross-region movement of the human body entering the bright area is a positive fluctuation, the fluctuation corresponding to the cross-region movement of the human body leaving the bright area is a negative fluctuation, the fluctuation corresponding to the cross-region movement of the human body entering the dark area is a negative fluctuation, and the fluctuation corresponding to the cross-region movement of the human body leaving the dark area is a positive fluctuation.

[0073] Therefore, the time width of the fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P is mainly related to the time width of the human body completing the corresponding cross-region movement. In the application scenario of long-distance detection based on high installation or side installation, since the areas of the partitions corresponding to different windows are large and scattered, the cross-region movements generated by the human body passing through the corresponding partitions are not coherent. The corresponding fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P are also not coherent. Then the frequency of the corresponding fluctuating changes is directly corresponding to the time width of the fluctuating changes and is related to the human body movement speed. Therefore, within the normal human body movement speed range, even in the application scenario of long-distance detection, the frequency of the fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P as an effective signal mainly concentrates in the range of 0.3 Hz to 10 Hz.

[0074] Furthermore, when the human body 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 bright and dark areas within each partition are directly related to the density of the fluctuating changes 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 fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P, which makes the corresponding fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P more coherent. Therefore, in the subsequent signal processing, based on the coherence of the fluctuating changes as effective signals, the detectability of the effective signals in terms of intensity and frequency can be improved.

[0075] In addition, the higher the resolution of the infrared detection device, the denser the fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P. And based on the increase in the density of the fluctuating changes in the detection signal output by the pyroelectric infrared sensor 20P, superposition of the fluctuating changes may be formed to increase the intensity and frequency of the fluctuating changes as effective signals. That is to say, in the state where the resolution of the infrared detection device is improved, the frequency of the effective signals in the detection signal may be increased and further concentrated in the frequency range deviating from 0.3 Hz within the range of 0.3 Hz to 10 Hz.

[0076] Therefore, in the commercial product design concept of the existing infrared detection devices, for the purpose of increasing the detection distance, it is usually necessary to increase the window area in the multi-window lens 10P to ensure the signal intensity in the detection signal related to the human body cross-region movement, and increase the number of windows of the multi-window lens to ensure the resolution of the infrared detection device. And in the signal processing rule of the detection signal, generally, a frequency greater than or equal to 0.3 Hz is used as the high-pass cut-off frequency of the corresponding amplifier circuit to avoid the risk of baseline drift due to the high-pass cut-off frequency approaching the DC component while ensuring the energy ratio of the effective signals.

[0077] In the passive infrared detection device of the present invention, the passive infrared detection device utilizes the characteristic that the detection signal output by the pyroelectric infrared sensor 20P has an integration characteristic (temperature change generates charge accumulation). Corresponding to the application scenario of long-distance detection, although the movement of the human body as a heat source inside the bright area or the dark area does not theoretically cause a fluctuating change in the detection signal output by the pyroelectric infrared sensor 20P because no cross-area action is formed, the temperature change corresponding to the cross-area movement of the human body can generate a slowly varying component close to direct current in the detection signal based on the cumulative change of charges, thereby generating an unexpected slowly varying signal below 0.3 Hz in the detection signal. By using the slowly varying signal below 0.3 Hz in the detection signal as an effective signal, the detection of the cross-area action of the human body at a long distance is realized.

[0078] That is to say, the detection signal output by the pyroelectric infrared sensor 20P has an integration characteristic. The slowly varying signal below 0.3 Hz generated in the detection signal based on this characteristic of the pyroelectric infrared sensor 20P is different in generation mode from the effective signal. Therefore, this slowly varying signal is usually regarded as an unexpected interference change. The passive infrared detection device of the present invention utilizes the corresponding relationship between this slowly varying signal and the cross-area action of the human body in the application scenario of long-distance detection, and uses the slowly varying signal below 0.3 Hz in the detection signal as an effective signal to realize the detection of the cross-area action of the human body at a long distance. Thus, it can not only ensure the energy proportion of the effective signal in the detection signal based on the characteristic that the detection signal output by the pyroelectric infrared sensor 20P has an integration characteristic, but also reduce the energy proportion of the interference signal in the detection signal because the signal usually regarded as an unexpected interference change is used as the effective signal.

[0079] Specifically, as described above, when the human body acting as a heat source passes through the partition corresponding to any window, the fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P correspond to the cross-region actions of the human body entering the bright area, leaving the bright area, entering the dark area, and leaving the dark area. And when the fluctuation corresponding to the cross-region action of the human body entering the bright area is a positive fluctuation, the fluctuation corresponding to the cross-region action of the human body leaving the bright area is a negative fluctuation, the fluctuation corresponding to the cross-region action of the human body entering the dark area is a negative fluctuation, and the fluctuation corresponding to the cross-region action of the human body leaving the dark area is a positive fluctuation. Among them, although the movement of the human body acting as a heat source inside the bright area or the dark area does not theoretically cause fluctuation changes in the detection signal output by the pyroelectric infrared sensor 20P because no cross-region action is formed, after the human body enters the bright area, the pyroelectric unit 21P corresponding to the bright area in a pair of the pyroelectric units 21P will generate charge accumulation based on the temperature change formed by the movement of the human body, thereby generating a slowly varying component close to direct current in the detection signal, such as generating a positive slowly varying component close to direct current. And after the human body enters the dark area, the pyroelectric unit 21P corresponding to the dark area in a pair of the pyroelectric units 21P will also generate charge accumulation based on the temperature change formed by the movement of the human body, thereby generating a slowly varying component close to direct current in the detection signal, such as generating a negative slowly varying component close to direct current. Thus, a slowly varying signal with a change period close to the time when the human body passes through the corresponding partition is generated. Corresponding to the long-distance detection application scenario with a detection distance greater than 10 meters, within the normal moving speed range of the human body, the frequency of this slowly varying signal is concentrated in the frequency range below 0.3 Hz.

[0080] It can be understood that in the description of the present invention, the long-distance detection application scenario greater than 10 meters does not limit the application scenario of the passive infrared detection device, but indicates that by using the aforementioned slowly varying signal below 0.3 Hz in the detection signal as the effective signal, the maximum effective detection distance of the passive infrared detection device of the present invention can be increased to greater than 10 meters. Thus, based on the long-distance detection requirement, the requirements for the window area and the number of windows of the multi-window lens 10P are reduced, which correspondingly facilitates the realization of long-distance detection applications with a smaller size of the multi-window lens 10P to adapt to the trend of miniaturized products.

[0081] It is worth mentioning that the maximum effective detection distance of the passive infrared detection device in the present invention is increased to a state greater than 10 meters. The specific application scenarios of the passive infrared detection device are diverse. For example, the passive infrared detection device can both achieve detection of a large detection area based on a large detection angle setting in a low installation scenario, and can also achieve detection of a large detection area with a small detection angle setting in a high installation scenario, and can also achieve detection of a long-distance and / or large detection area in a side installation scenario.

[0082] Further referring to FIGS. Figure 2A and Figure 2B shown, the circuit structure of the passive infrared detection device according to an embodiment of the present invention and the corresponding voltage changes of the circuit after being powered on are schematically shown. The passive infrared detection device includes a pyroelectric infrared sensor 20 and an amplifier circuit 30 capable of amplifying and processing the AC component of the detection signal output by the pyroelectric infrared sensor 20. The amplifier circuit 30 is electrically connected to the pyroelectric infrared sensor 20 to amplify and process the AC component of the detection signal output by the pyroelectric infrared sensor 20, and is set to have a high-pass cut-off frequency lower than 0.3 Hz, so that the slow-changing signal generated based on the aforementioned integration characteristic 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. The high-pass cut-off frequency of the amplifier circuit 30 is preferably set to be less than or equal to 0.2 Hz, so as to be conducive to increasing the energy ratio of the slow-changing signal generated based on the aforementioned integration characteristic and improving the detectability of the effective signal in terms of intensity and frequency.

[0083] Specifically, in this embodiment of the present invention, the amplifier circuit 30 uses an in-phase negative feedback amplifier circuit as the primary amplifier circuit 31, and the primary amplifier circuit 31 is set to have a high-pass cut-off frequency lower than 0.3 Hz, so as to utilize the electrical characteristics of the in-phase negative feedback amplifier circuit having a high input impedance and a low output impedance to enable the amplifier circuit 30 to amplify the slow-changing signal generated based on the aforementioned integration characteristic in the detection signal with a stable amplification factor.

[0084] Corresponding to the state where the in-phase negative feedback amplifier circuit is the primary amplifier circuit 31 in the amplifier circuit 30, the primary amplifier circuit 31 has an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor 20 to access the detection signal output from the pyroelectric infrared sensor 20. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other, so as to form an in-phase negative feedback amplifier circuit with the amplification factor related to R1 / R2 and the high-pass cut-off frequency related to R2C1.

[0085] It can be understood that, in the circuit structure of the passive infrared detection device shown Figure 2A in, the inverting input terminal of the amplifier OP1 is specifically connected to one end of the capacitor C1 via the resistor R2, and the other end of the capacitor C1 is grounded for AC, so as to form the structural feature that the inverting input terminal of the operational amplifier OP1 is grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other. Corresponding to the structural feature that the inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series with each other, the relative positional relationship between the resistor R2 and the capacitor C1 connected in series with each other does not constitute a limitation to the present invention. That is to say, in some embodiments of the present invention, the inverting input terminal of the amplifier OP1 can also be connected to one end of the resistor R2 via the capacitor C1, and the other end of the resistor R2 is grounded for AC.

[0086] It is worth mentioning that the relationship between the high-pass cut-off frequency f of the primary amplifier circuit 31 and R2 and C1 satisfies the formula Therefore, the lower the high-pass cut-off frequency f of the primary amplifier circuit 31, the larger the value of R2C1. When the high-pass cut-off frequency f of the primary amplifier circuit 31 is reduced from 0.3 Hz to 0.1 Hz, the value of R2C1 will increase by two times. The amplification factor A of the primary amplifier circuit 31 ν is related to R1 and R2 and satisfies the formula Therefore, based on the magnification requirement, R1 is much larger than R2. The time constant RC of the primary amplification circuit 31 corresponds to (R1 + R2)C1. Then, the power-on time described above represents the time from when the corresponding amplification circuit is powered on until it can stably amplify and output the input signal. The power-on time of the primary amplification circuit 31 is proportional to the charge and discharge time of the capacitor C1 and is related to the time constant RC of the primary amplification circuit 31. Therefore, when the resistor R2 and the capacitor C1 connected in series in the primary amplification circuit 31 correspond to Figure 3A When the circuit structure of the existing infrared detection device shown in Figure 3A keeps the AC grounded in a direct grounding manner, the power-on time of the amplification circuit 30 will be very long.

[0087] It can be understood that the foregoing formula is only used to explain the influence of the high-pass cut-off frequency of the primary amplification circuit 31 on the power-on time of the amplification circuit 30, and it does not constitute a limitation on the calculation method of the actual high-pass cut-off frequency of the primary amplification circuit 31. In the state where the primary amplification circuit 31 is set as an in-phase negative feedback amplification circuit, those skilled in the art can calculate the high-pass cut-off frequency of the primary amplification circuit 31 according to the actual circuit structure.

[0088] Specifically, in this embodiment of the present invention, taking the secondary amplification circuit 32 of the amplification circuit 30 as an inverting negative feedback amplification circuit as an example, the amplification circuit 30 further includes a series RC circuit 33 disposed between the primary amplification circuit 31 and the secondary amplification circuit 32. The series RC circuit 33 is equivalent to a capacitor and a resistor connected in series. The secondary amplification circuit 32 is an inverting negative feedback amplification circuit and has an operational amplifier OP2 and a feedback resistor R3. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R3. One end of the series RC circuit 33 is electrically connected to the output terminal of the primary amplification circuit 30 (i.e., the output terminal of the operational amplifier OP1 of the primary amplification circuit 30), and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2.

[0089] So when the resistor R2 and the capacitor C1 connected in series in the primary amplification circuit 31 correspond to Figure 3A When the circuit structure of the existing infrared detection device shown in Figure 3A keeps the AC grounded in a direct grounding manner, the potential change sequence at the inverting input terminal and the output terminal of the operational amplifier OP1, and the inverting input terminal and the output terminal of the operational amplifier OP2 of the amplification circuit 30 after being powered on corresponds to Figure 3BThe four curves A, B, C, and D in [the figure]. It can be seen that at the beginning when the amplifier circuit 30 is powered on, the potential at the inverting input terminal of the operational amplifier OP1 is close to 0V and can only tend to be stable after a period of time t1. Corresponding to this time period, the potential output at the output terminal of the operational amplifier OP1 approaches its supply voltage and is in a saturated output state. As a result, after the potential at the inverting input terminal of the operational amplifier OP1 becomes stable, the potential at the inverting input terminal of the operational amplifier OP2 still needs a period of time t2 to become stable. That is to say, the length of the t2 time period is directly related to the length of the time during which the output terminal of the operational amplifier OP1 is in a saturated output state and is related to the length of the t1 time period. And the output terminal of the operational amplifier OP2 can only stably amplify and output the corresponding AC signal when the potential at the inverting input terminal of the operational amplifier OP2 becomes stable. Therefore, the power-on time of the amplifier circuit 30 corresponds to the sum of the t1 time period and the t2 time period. Among them, the length of the t1 time period corresponds to the power-on time of the primary amplifier circuit 31 and is directly proportional to the time constant RC of the primary amplifier circuit 31. That is, when the high-pass cut-off frequency f of the primary amplifier circuit 31 is lower, the t1 time period is longer. And the length of the t2 time period is directly proportional to the length of the t1 time period. Corresponding to the lower the high-pass cut-off frequency f of the primary amplifier circuit 31, the longer the power-on time of the amplifier circuit 30. This is also one of the reasons why the existing infrared detection devices in practical applications usually use a frequency greater than or equal to 0.3Hz as the high-pass cut-off frequency of the corresponding amplifier circuit.

[0090] That is to say, in the primary amplifier circuit 31, the mutually series-connected resistor R2 and capacitor C1 correspond to Figure 3A The circuit structure of the existing infrared detection device shown is in a state of keeping the AC grounded by directly grounding. When the amplifier circuit 30 of the present invention is set to have a state with a high-pass cut-off frequency lower than 0.3Hz, the problem of too long power-on time of the amplifier circuit 30 will occur.

[0091] Different from the traditional in-phase negative feedback amplifier circuit that keeps the inverting input terminal of the operational amplifier OP1 grounded for AC by directly grounding the mutually series-connected resistor R2 and capacitor C1, in the primary amplifier circuit 31 of the amplifier circuit 30 of the present invention, the mutually series-connected resistor R2 and capacitor C1 correspond to Figure 2AThe illustrated embodiment further accesses a DC bias voltage Vref1 at one end that remains grounded for alternating current, where the difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 tends to be the same within a range of less than or equal to 0.5V. In this way, at the beginning of power-on of the passive infrared detection device, the voltages at the non-inverting input terminal and the inverting input terminal of the operational amplifier OP1 can approach each other, enabling the output at the output terminal of the operational amplifier OP1 to quickly tend to be stable, correspondingly shortening the t1 time period and being able to shorten the power-on time of the amplifier circuit 30. In this way, when the high-pass cut-off frequency of the amplifier circuit 30 is set at a frequency lower than 0.3Hz, the problem of excessive power-on time caused by too low a high-pass cut-off frequency of the amplifier circuit 30 can be solved.

[0092] Specifically, when the mutually series-connected resistor R2 and capacitor C1 correspond to Figure 2A When the DC bias voltage Vref1 is further accessed at one end that remains grounded for alternating current, the sequence of potential changes at the inverting input terminal and the output terminal of the operational amplifier OP1, and the inverting input terminal and the output terminal of the operational amplifier OP2 after the amplifier circuit 30 is powered on corresponds to Figure 2B the four curves A, B, C, and D in. It can be seen that at the beginning of power-on of the amplifier circuit 30, the potential at the inverting input terminal of the operational amplifier OP1 immediately tends to be stable, and the potential output at the output terminal of the operational amplifier OP1 only presents a transient saturated output state, that is, the aforementioned t1 time period corresponding to the power-on time of the primary amplifier circuit 31 is shortened to a transient. In this way, in a state where the length of the t2 time period is directly proportional to the length of the t1 time period, the t2 time period is synchronously shortened to shorten the power-on time of the amplifier circuit 30.

[0093] It can be understood that when the mutually series-connected resistor R2 and capacitor C1 correspond to Figure 2A When the DC bias voltage Vref1 is further accessed at one end that remains grounded for alternating current, at the beginning of power-on of the amplifier circuit 30, the potential at the inverting input terminal of the operational amplifier OP1 immediately tends to be stable, and the potential output at the output terminal of the operational amplifier OP1 only presents a transient saturated output state, that is, the aforementioned t1 time period corresponding to the power-on time of the primary amplifier circuit 31 is shortened to a transient. Therefore, the mutually series-connected resistor R2 and capacitor C1 correspond to Figure 2AIn the way that the DC bias voltage Vref1 is further connected to one end that is grounded for alternating current, the presence or absence of the effect of shortening the power-on time of the primary amplifier circuit 31 is not limited by the high-pass cut-off frequency of the primary amplifier circuit 31. That is to say, the amplifier circuit 30 of the present invention is also applicable to existing infrared detection devices with a high-pass cut-off frequency greater than or equal to 0.3 Hz.

[0094] In addition, those skilled in the art should understand that in the above and subsequent descriptions of the present invention, the relevant descriptions of voltage / potential are descriptions of the corresponding voltage / potential of the passive infrared detection device and the amplifier circuit 30 in the powered-on state, which are only used to understand and describe the working principles of the passive infrared detection device and the amplifier circuit 30 of the present invention, and do not constitute a limitation on whether the passive infrared detection device and the amplifier circuit 30 are in the powered-on state.

[0095] It is worth mentioning that in this embodiment of the present invention, the operational amplifier OP1 of the primary amplifier circuit 31 and the operational amplifier OP2 of the secondary amplifier circuit 32 are both set to be powered in a single power supply mode, which is beneficial to simplifying the power supply structure of the amplifier circuit 30 and reducing the power supply cost of the amplifier circuit 30.

[0096] Furthermore, referring to Figure 4 as shown in the accompanying drawings of the specification of the present invention, on the basis of the structure of the passive infrared detection device in the above embodiment of the present invention, the specific wiring method of further connecting the end of the series-connected resistor R2 and capacitor C1 that is grounded for alternating current to the DC bias voltage Vref1 is schematically shown. The amplifier circuit 30 is provided with a first voltage dividing circuit 34 to provide the DC bias voltage Vref1 for the series-connected resistor R2 and capacitor C1. The first voltage dividing circuit 34 has a first voltage dividing resistor 341 and a first resistor to ground 342. One end of the first resistor to ground 342 is grounded, and the other end of the first resistor to ground 342 is connected to the DC power supply voltage through the first voltage dividing resistor 341. The end of the series-connected resistor R2 and capacitor C1 that is connected to the DC bias voltage Vref1 is electrically connected between the first voltage dividing resistor 341 and the first resistor to ground 342, so that this end of the series-connected resistor R2 and capacitor C1 can be grounded for alternating current and can be connected to the DC bias voltage Vref1 related to the ratio between the first voltage dividing resistor 341 and the first resistor to ground 342 in the state where the first resistor to ground 342 is connected to the DC power supply voltage through the first voltage dividing resistor 341, which is thus simple and easy to implement.

[0097] Specifically, the first ground resistor 342 of the first voltage dividing circuit 34 is electrically connected to the power supply terminal of the pyroelectric infrared sensor 20 via the first voltage dividing resistor 341, so as to avoid connecting an additional power supply, and thus can simplify the structure of connecting the mutually series-connected resistor R2 and capacitor C1 to the DC bias voltage Vref1 and reduce the cost of connecting the mutually series-connected resistor R2 and capacitor C1 to the DC bias voltage Vref1.

[0098] It can be understood that there are various specific wiring methods for further connecting the end of the mutually series-connected resistor R2 and capacitor C1 that is grounded for AC to the DC bias voltage Vref1. For example, the amplifier circuit 30 can also be arranged such that a reference voltage source (such as a three-terminal voltage regulator) provides the DC bias voltage Vref1 for the mutually series-connected resistor R2 and capacitor C1. While using the constant voltage characteristic of the reference voltage source to provide the DC bias voltage Vref1 for the mutually series-connected resistor R2 and capacitor C1, the low internal resistance characteristic of the reference voltage source is used to ground the mutually series-connected resistor R2 and capacitor C1 for AC. Those skilled in the art can calculate or test the DC bias voltage Vref1 at the end of the mutually series-connected resistor R2 and capacitor C1 that is grounded for AC to determine whether the DC bias voltage Vref1 converges to the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1. Therefore, the specific wiring for further connecting the end of the mutually series-connected resistor R2 and capacitor C1 that is grounded for AC to the DC bias voltage Vref1 is only an example and does not constitute a limitation to the present invention.

[0099] Specifically, for the purpose of applying the DC bias voltage Vref2 to the non-inverting input terminal of the operational amplifier OP2, the amplifier circuit 30 is optionally correspondingly Figure 4 further arranged such that a second voltage dividing circuit 35 provides the DC bias voltage Vref2 for the non-inverting input terminal of the operational amplifier OP2. The second voltage dividing circuit 35 has a second voltage dividing resistor 351 and a second ground resistor 352. One end of the second ground resistor 352 is grounded, and the other end of the second ground resistor 352 is connected to the DC power supply voltage via the second voltage dividing resistor 351. The non-inverting input terminal of the operational amplifier OP2 is electrically connected between the second voltage dividing resistor 351 and the second ground resistor 352, so as to apply the DC bias voltage Vref2 related to the ratio between the second voltage dividing resistor 351 and the second ground resistor 352 in the state where the second ground resistor 352 is connected to the DC power supply voltage via the second voltage dividing resistor 351.

[0100] Preferably, the second voltage dividing circuit 35 and the first voltage dividing circuit 34 are connected to the DC power supply voltage in a manner of being connected to the same power supply, such as being electrically connected to the power supply terminal of the pyroelectric infrared sensor 20 to be connected to the same power supply.

[0101] It is worth mentioning that, in the passive infrared detection device corresponding to Figure 2A and Figure 4 shown in the present invention, both the operational amplifier OP1 and the operational amplifier OP2 are arranged to be powered by a single power supply, which is beneficial to simplifying the power supply structure of the primary amplification circuit 31 and reducing the power supply cost of the primary amplification circuit 31. In some other embodiments of the present invention, the operational amplifier OP1 and the operational amplifier OP2 can also correspond to Figure 5 both be arranged to be powered by a dual power supply, and the present invention does not limit this.

[0102] Furthermore, in these embodiments of the present invention, the non-inverting input terminal of the operational amplifier OP1 of the primary amplification circuit 31 is electrically connected to the pyroelectric infrared sensor 20 to access the detection signal output from the pyroelectric infrared sensor 20, and in the figure, the electrical connection relationship between the operational amplifier OP1 and the pyroelectric infrared sensor 20 is specifically shown in an exemplary electrical connection manner where the non-inverting input terminal of the operational amplifier OP1 is directly connected to the signal output terminal of the pyroelectric infrared sensor 20. Corresponding to this exemplary electrical connection manner, the DC bias voltage Vrefin accessed by the operational amplifier OP1 at the non-inverting input terminal is the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, and the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20 is generally 0.7V. Therefore, based on the matching requirement of the DC bias voltage Vrefin accessed by the operational amplifier OP1 at the non-inverting input terminal and its power supply voltage, or based on the requirement of the magnification factor for the magnitude of the DC bias voltage Vrefin accessed by the operational amplifier OP1 at the non-inverting input terminal, in some embodiments of the present invention, it can also correspond to Figure 6A and Figure 6B respectively at Figure 2A and Figure 4On the basis of the structure of the amplification circuit 30 shown, a DC blocking voltage dividing circuit 36 is further provided. The DC blocking voltage dividing circuit 36 has a voltage dividing resistor 361, a pair of ground resistors 362 and a DC blocking capacitor 363. One end of the ground resistor 362 is grounded, and the other end of the ground resistor 362 is connected to the DC supply voltage through the voltage dividing resistor 361. For example, it is connected to the power supply terminal of the pyroelectric infrared sensor 20 to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor 20, and is electrically connected to the pyroelectric infrared sensor 20 through the DC blocking capacitor 363. The non-inverting input terminal of the operational amplifier OP1 is electrically connected between the voltage dividing resistor 361 and the ground resistor 362. In this way, the operational amplifier OP1 can not only access the AC component in the detection signal output from the pyroelectric infrared sensor 20 at its non-inverting input terminal, but also access the DC bias voltage Vrefin related to the ratio between the voltage dividing resistor 361 and the ground resistor 362 in the state where the ground resistor 362 is connected to the DC supply voltage through the voltage dividing resistor 361.

[0103] In addition, also based on the matching requirement of the DC bias voltage Vrefin accessed by the operational amplifier OP1 at its non-inverting input terminal and its supply voltage, or based on the requirement for the magnitude of the DC bias voltage Vrefin accessed by the operational amplifier OP1 at its non-inverting input terminal due to the amplification factor, in some other embodiments of the present invention, it is also possible to correspond to Figure 7A In Figure 2A On the basis of the structure of the amplification circuit 30 shown, a third voltage dividing circuit 37 is further provided. The third voltage dividing circuit 37 has a third voltage dividing resistor 371 and a voltage matching resistor 372. The non-inverting input terminal of the operational amplifier OP1 is connected to the DC supply voltage through the third voltage dividing resistor 371. For example, it is connected to the power supply terminal of the pyroelectric infrared sensor 20 to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor 20, and is electrically connected to the pyroelectric infrared sensor 20 through the voltage matching resistor 372. In this way, by using the matching setting of the self-impedance of the pyroelectric infrared sensor 20 and the third voltage dividing circuit 37, in the state where the voltage at the end of the voltage matching resistor 372 electrically connected to the pyroelectric infrared sensor 20 corresponds to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, the voltage at the other end of the voltage matching resistor 372 can match the requirement for the magnitude of the DC bias voltage Vrefin accessed by the operational amplifier OP1 at its non-inverting input terminal.

[0104] It is worth mentioning that Figure 7ABased on the structure of the amplification circuit 30 shown, in order for the voltage at one end of the voltage matching resistor 372 electrically connected to the pyroelectric infrared sensor 20 to correspond to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20, so that the voltage at the other end of the voltage matching resistor 372 can match the magnitude requirement of the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1, there are relatively high requirements for the resistance accuracy and stability of the voltage matching resistor 372. Therefore, when there is a deviation in the resistance value of the voltage matching resistor 372 used in practice or a deviation occurs due to environmental influence, it is easy to cause impedance mismatch and trigger the attenuation problem of the detection signal connected to the non-inverting input terminal of the operational amplifier OP1. In view of this, in another embodiment of the present invention, the amplification circuit 30 corresponds to Figure 7B A capacitor is further connected in parallel to the voltage matching resistor 372. Based on the method of connecting a capacitor in parallel to the voltage matching resistor 372, when there is a deviation in the resistance value of the voltage matching resistor 372 used in practice or a deviation occurs due to environmental influence, the impedance matching is optimized to avoid the problem of signal attenuation.

[0105] It can be understood that corresponding to Figures 6A to 7B For the amplification circuit 30 shown, when the secondary amplification circuit 32 adopts an inverting negative feedback amplification circuit, when the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is raised relative to the DC bias voltage Vrefpir of the pyroelectric infrared sensor 20 based on the setting of the DC blocking voltage dividing circuit 36 or the third voltage dividing circuit 37, the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is preferably set to converge to the DC bias voltage Vref2 connected to the non-inverting input terminal of the operational amplifier OP2 within a difference range less than or equal to 0.5V, so that the bias voltage of the signal output from the output terminal of the operational amplifier OP1 can quickly converge to the DC bias voltage Vref2 connected to the non-inverting input terminal of the operational amplifier OP2, thereby further shortening the power-on time of the amplification circuit.

[0106] In particular, in these above-described embodiments of the present invention, the secondary amplification circuit 32 is exemplified by an inverting negative feedback amplification circuit. Based on the foregoing description of the present invention, in a state where the primary amplification circuit 31 of the amplification circuit 30 is arranged as a non-inverting negative feedback amplification circuit, the arrangement of the secondary amplification circuit 32 as an inverting negative feedback amplification circuit is only an example to show the influence of the power-on time of the primary amplification circuit 31 on the power-on time of the amplification circuit. When a DC bias voltage Vref1 is further connected to one end of the mutually series-connected resistor R2 and capacitor C1 of the primary amplification circuit 31 that is grounded for alternating current, and the difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5V and tends to be the same, the power-on time of the amplification circuit 30 can be shortened based on the shortening of the power-on time of the primary amplification circuit 31. Therefore, the specific circuit form of the secondary amplification circuit 32 does not constitute a limitation to the present invention.

[0107] That is to say, in the passive infrared detection device of the present invention, when the amplification circuit 30 is an amplification circuit with no less than two amplification stages and includes the secondary amplification circuit 32, the specific form of the secondary amplification circuit 32 does not constitute a limitation to the present invention. For example, the amplification circuit 30 can also correspond to Figure 8A and Figure 8B respectively, on the basis of the structure of the amplification circuit 30 shown in Figure 2A and Figure 6A replace the secondary amplification circuit 32 arranged as an inverting negative feedback amplification circuit with a non-inverting negative feedback amplification circuit, so as to be able to eliminate the series RC circuit 33 arranged between the primary amplification circuit 31 and the secondary amplification circuit 32. Corresponding to the secondary amplification circuit 32, there is an operational amplifier OP3, a feedback resistor R4, a resistor R5, and a capacitor C2. The output terminal of the operational amplifier OP3 is connected to the inverting input terminal of the operational amplifier OP3 through the feedback resistor R4. The non-inverting input terminal of the operational amplifier OP3 is electrically connected to the output terminal of the operational amplifier OP1 of the primary amplification circuit 31. The inverting input terminal of the operational amplifier OP3 is further grounded for alternating current through the mutually series-connected resistor R5 and capacitor C2, and preferably, a DC bias voltage Vref3 is connected. The difference between the DC bias voltage Vref3 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 of the primary amplification circuit 31 is within a range of less than or equal to 0.5V and tends to be the same, so as to be beneficial to further shortening the power-on time of the amplification circuit 30.

[0108] Preferably, corresponding to Figure 8A andFigure 8B In the embodiment, the DC bias voltage Vref3 is set to be the same as the DC bias voltage Vref1. For example, the way of connecting the AC-grounded ends of the mutually series-connected resistor R2 and capacitor C1 to the AC-grounded ends of the mutually series-connected resistor R5 and capacitor C2 and connecting them to the same DC bias voltage makes the DC bias voltage Vref3 set to be the same as the DC bias voltage Vref1, so as to be beneficial to further shortening the power-on time of the amplifier circuit 30 and ensuring the stability of the working state of the amplifier circuit 30.

[0109] Those skilled in the art should understand that, based on the structure of the passive infrared detection device in the above embodiments of the present invention, the operational amplifier OP1 of the primary amplifier circuit 31 can be integrated with the operational amplifier OP2 or OP3 of the secondary amplifier circuit 32 on the same chip. The amplifier circuit 30 is also suitable for further combining with conventional improvement methods to enhance the relevant performance of the amplifier circuit 30. For example, a capacitor is 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 in-phase / anti-phase negative feedback amplifier circuit to prevent self-oscillation of the operational amplifier and filter high-frequency interference to ensure the stability of the amplifier circuit 30. And a capacitor is connected to the power supply terminal of the operational amplifier to purify the power network to ensure the anti-interference performance of the amplifier circuit 30. The present invention does not limit this.

[0110] Those skilled in the art can understand that the above embodiments are only examples, and the features of different embodiments can be combined with each other to obtain embodiments that are easily conceivable according to the content disclosed in the present invention but not clearly pointed out in the drawings.

[0111] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the drawings are only examples and do not limit the present invention. The object of the present invention has been fully and effectively achieved. The function and structural principle of the present invention have been demonstrated and explained in the embodiments. Without departing from the above principle, the embodiments of the present invention can have any deformation or modification.

Claims

1. Passive infrared detection device, characterized in that, Comprising: A multi-window lens; A pyroelectric infrared sensor, wherein a partition is formed on the photosensitive surface of the pyroelectric infrared sensor through the window of the multi-window lens; And An amplifier circuit, wherein the amplifier circuit is electrically connected to the pyroelectric infrared sensor to amplify the AC component of the detection signal output by the pyroelectric infrared sensor, and is set to have a high-pass cut-off frequency lower than 0.3 Hz, so that the slow-changing signal in the detection signal whose change period is close to the time when a human body passes through the partition 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.

2. The passive infrared detection device according to claim 1, wherein the amplifier circuit uses an in-phase negative feedback amplifier circuit as the primary amplifier circuit, and is correspondingly set to have a high-pass cut-off frequency lower than 0.3 Hz, and has an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor to access the detection signal output from the pyroelectric infrared sensor. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the resistor R2 and the capacitor C1 connected in series.

3. The passive infrared detection device according to claim 2, wherein a DC bias voltage Vref1 is further connected to one end of the resistor R2 and the capacitor C1 connected in series that is grounded for AC. The difference between the DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 is within a range of less than or equal to 0.5 V and tends to be the same.

4. The passive infrared detection device according to claim 3, wherein the amplifier circuit is set to provide the DC bias voltage Vref1 to the resistor R2 and the capacitor C1 connected in series through a first voltage dividing circuit. The first voltage dividing circuit has a first voltage dividing 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 power supply voltage through the first voltage dividing resistor. One end of the resistor R2 and the capacitor C1 connected in series that accesses the DC bias voltage Vref1 is electrically connected between the first voltage dividing resistor and the first resistor to ground, so that this end of the resistor R2 and the capacitor C1 connected in series can be grounded for AC and can access the DC bias voltage Vref1 related to the ratio between the first voltage dividing resistor and the first resistor to ground when the first resistor to ground is connected to the DC power supply voltage through the first voltage dividing resistor.

5. The passive infrared detection device according to claim 4, wherein the first ground resistor of the first voltage dividing circuit is electrically connected to the power supply terminal of the pyroelectric infrared sensor through the first voltage dividing resistor to access a DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

6. The passive infrared detection device according to claim 3, wherein the operational amplifier OP1 is powered in a single power supply mode.

7. The passive infrared detection device according to claim 6, wherein the amplifying circuit further includes a DC blocking voltage dividing circuit, the DC blocking voltage dividing circuit having a voltage dividing 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 accesses the DC power supply voltage through the voltage dividing resistor, and is electrically connected to the pyroelectric infrared sensor through the DC blocking capacitor, and the non-inverting input terminal of the operational amplifier OP1 is electrically connected between the voltage dividing resistor and the ground resistor.

8. The passive infrared detection device according to claim 7, wherein the ground resistor is connected to the power supply terminal of the pyroelectric infrared sensor through the voltage dividing resistor to access a DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

9. The passive infrared detection device according to claim 6, wherein the amplifying circuit further includes a third voltage dividing circuit, the third voltage dividing circuit having a third voltage dividing resistor and a voltage matching resistor, wherein the non-inverting input terminal of the operational amplifier OP1 accesses the DC power supply voltage through the third voltage dividing resistor and is electrically connected to the pyroelectric infrared sensor through the voltage matching resistor.

10. The passive infrared detection device according to claim 9, wherein the non-inverting input terminal of the operational amplifier OP1 is connected to the power supply terminal of the pyroelectric infrared sensor through the third voltage dividing resistor to access a DC power supply voltage from the power supply terminal of the pyroelectric infrared sensor.

11. The passive infrared detection device according to claim 10, wherein a capacitor is further connected in parallel to the voltage matching resistor of the third voltage dividing circuit.

12. The passive infrared detection device according to claim 3, wherein the operational amplifier OP1 is powered in a dual power supply mode.

13. The passive infrared detection device according to any one of claims 3 to 12, wherein the amplifying circuit further includes a secondary amplifying circuit and a series RC circuit disposed between the primary amplifying circuit and the secondary amplifying circuit, corresponding to the series RC circuit being equivalent to a capacitor and a resistor connected in series, wherein the secondary amplifying circuit is an inverting negative feedback amplifying circuit having an operational amplifier OP2 and a feedback resistor R3, 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 R3, and one end of the series RC circuit is electrically connected to the output terminal of the primary amplifying circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2.

14. The passive infrared detection device according to any one of claims 7 to 11, wherein the amplifier circuit further includes a secondary amplifier circuit and a series RC circuit disposed between the primary amplifier circuit and the secondary amplifier circuit. The corresponding series RC circuit is equivalent to a capacitor and a resistor connected in series. The secondary amplifier circuit uses an inverting negative feedback amplifier circuit and has an operational amplifier OP2 and a feedback resistor R3. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R3. One end of the series RC circuit is electrically connected to the output terminal of the primary amplifier circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2. The DC bias voltage Vref2 applied to the non-inverting input terminal of the operational amplifier OP2 is set to converge within a difference range of less than or equal to 0.5V to the DC bias voltage Vrefin applied to the non-inverting input terminal of the operational amplifier OP1.

15. The passive infrared detection device according to claim 14, wherein the amplifier circuit is arranged to provide the DC bias voltage Vref2 for the non-inverting input terminal of the operational amplifier OP2 with a second voltage dividing circuit. The second voltage dividing circuit has a second voltage dividing 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 through the second voltage dividing resistor. The non-inverting input terminal of the operational amplifier OP2 is electrically connected between the second voltage dividing resistor and the second resistor to ground, so as to access the DC bias voltage Vref2 associated with the ratio between the second voltage dividing resistor and the second resistor to ground in a state where the second resistor to ground is connected to the DC supply voltage through the second voltage dividing resistor.

16. The passive infrared detection device according to any one of claims 3 to 12, wherein the amplifier circuit further includes a secondary amplifier circuit. The secondary amplifier circuit uses a non-inverting negative feedback amplifier circuit and has an operational amplifier OP3, a feedback resistor R4, a resistor R5, and a capacitor C2. The output terminal of the operational amplifier OP3 is connected to the inverting input terminal of the operational amplifier OP3 through the feedback resistor R4. The non-inverting input terminal of the operational amplifier OP3 is electrically connected to the output terminal of the operational amplifier OP1 of the primary amplifier circuit 31. The inverting input terminal of the operational amplifier OP3 is further grounded for AC through the resistor R5 and the capacitor C2 connected in series.

17. The passive infrared detection device according to claim 16, wherein a DC bias voltage Vref3 is further applied to one end of the resistor R5 and the capacitor C2 connected in series that is grounded for AC. The DC bias voltage Vref3 and the DC bias voltage Vrefin applied to the non-inverting input terminal of the operational amplifier OP1 tend to be the same within a difference range of less than or equal to 0.5V.

18. The passive infrared detection device according to claim 17, wherein the DC bias voltage Vref3 is set to be the same as the DC bias voltage Vref1.

19. An amplifier circuit capable of shortening the power-on time, which is used to amplify the AC component of the detection signal output by a pyroelectric infrared sensor, is characterized in that The amplifier circuit uses a non-inverting negative feedback amplifier circuit as the primary amplifier circuit. Corresponding to the primary amplifier circuit, there is an operational amplifier OP1, a feedback resistor R1, a resistor R2, and a capacitor C1. 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 non-inverting input terminal of the operational amplifier OP1 is electrically connected to the pyroelectric infrared sensor to access the detection signal output from the pyroelectric infrared sensor. The inverting input terminal of the operational amplifier OP1 is further grounded for AC through the series-connected resistor R2 and capacitor C1 and is connected to a DC bias voltage Vref1. The DC bias voltage Vref1 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 tend to be the same within a difference range of less than or equal to 0.5V.

20. The amplifier circuit capable of shortening the power-on time according to claim 19, wherein the amplifier circuit is arranged to provide the DC bias voltage Vref1 for the series-connected resistor R2 and capacitor C1 with a first voltage dividing circuit. The first voltage dividing circuit has a first voltage dividing 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 through the first voltage dividing resistor. The end of the series-connected resistor R2 and capacitor C1 connected to the DC bias voltage Vref1 is electrically connected between the first voltage dividing resistor and the first resistor to ground, so that this end of the series-connected resistor R2 and capacitor C1 can be grounded for AC and can also be connected to the DC bias voltage Vref1 related to the ratio between the first voltage dividing resistor and the first resistor to ground when the first resistor to ground is connected to the DC supply voltage through the first voltage dividing resistor.

21. The amplifier circuit capable of shortening the power-on time according to claim 20, wherein the first resistor to ground of the first voltage dividing circuit is electrically connected to the power supply terminal of the pyroelectric infrared sensor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

22. The amplifier circuit capable of shortening the power-on time according to claim 19, wherein the operational amplifier OP1 is arranged to be powered in a single power supply mode.

23. The amplifier circuit capable of shortening the power-on time according to claim 22, wherein the amplifier circuit further includes a DC-blocking voltage-dividing circuit, the DC-blocking voltage-dividing circuit having a voltage-dividing resistor, a pair of ground resistors, and a DC-blocking capacitor, wherein one end of the ground resistor is grounded, the other end of the ground resistor is connected to the DC supply voltage through the voltage-dividing resistor, and is electrically connected to the pyroelectric infrared sensor through the DC-blocking capacitor, and the non-inverting input terminal of the operational amplifier OP1 is electrically connected between the voltage-dividing resistor and the ground resistor.

24. The amplifier circuit capable of shortening the power-on time according to claim 23, wherein the ground resistor is connected to the power supply terminal of the pyroelectric infrared sensor through the voltage-dividing resistor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

25. The amplifier circuit capable of shortening the power-on time according to claim 22, wherein the amplifier circuit further includes a third voltage-dividing circuit, the third voltage-dividing circuit having a third voltage-dividing resistor and a voltage matching resistor, wherein the non-inverting input terminal of the operational amplifier OP1 is connected to the DC supply voltage through the third voltage-dividing resistor and is electrically connected to the pyroelectric infrared sensor through the voltage matching resistor.

26. The amplifier circuit capable of shortening the power-on time according to claim 25, wherein the non-inverting input terminal of the operational amplifier OP1 is connected to the power supply terminal of the pyroelectric infrared sensor through the third voltage-dividing resistor to access the DC supply voltage from the power supply terminal of the pyroelectric infrared sensor.

27. The amplifier circuit capable of shortening the power-on time according to claim 26, wherein a capacitor is further connected in parallel with the voltage matching resistor of the third voltage-dividing circuit.

28. The amplifier circuit capable of shortening the power-on time according to claim 19, wherein the operational amplifier OP1 is powered in a dual-power supply mode.

29. The amplifier circuit capable of shortening the power-on time according to any one of claims 19 to 28, wherein the amplifier circuit further includes a secondary amplifier circuit and a series RC circuit disposed between the primary amplifier circuit and the secondary amplifier circuit, corresponding to the series RC circuit being equivalent to a capacitor and a resistor connected in series, wherein the secondary amplifier circuit is an inverting negative feedback amplifier circuit having an operational amplifier OP2 and a feedback resistor R3, 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 R3, and one end of the series RC circuit is electrically connected to the output terminal of the primary amplifier circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2.

30. The amplifier circuit capable of shortening the power-on time according to any one of claims 23 to 27, wherein the amplifier circuit further includes a secondary amplifier circuit and a series RC circuit disposed between the primary amplifier circuit and the secondary amplifier circuit. The series RC circuit is equivalent to a capacitor and a resistor connected in series. The secondary amplifier circuit is an inverting negative feedback amplifier circuit and has an operational amplifier OP2 and a feedback resistor R3. The output terminal of the operational amplifier OP2 is connected to the inverting input terminal of the operational amplifier OP2 through the feedback resistor R3. One end of the series RC circuit is electrically connected to the output terminal of the primary amplifier circuit, and the other end is electrically connected to the inverting input terminal of the operational amplifier OP2. The DC bias voltage Vref2 applied to the non-inverting input terminal of the operational amplifier OP2 is set to converge within a difference range less than or equal to 0.5V to the DC bias voltage Vrefin applied to the non-inverting input terminal of the operational amplifier OP1.

31. The amplifier circuit capable of shortening the power-on time according to claim 30, wherein the amplifier circuit is arranged to provide the DC bias voltage Vref2 for the non-inverting input terminal of the operational amplifier OP2 with a second voltage dividing circuit. The second voltage dividing circuit has a second voltage dividing 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 through the second voltage dividing resistor. The non-inverting input terminal of the operational amplifier OP2 is electrically connected between the second voltage dividing resistor and the second resistor to ground to access the DC bias voltage Vref2 related to the ratio between the second voltage dividing resistor and the second resistor to ground in a state where the second resistor to ground is connected to the DC supply voltage through the second voltage dividing resistor.

32. The amplifier circuit capable of shortening the power-on time according to any one of claims 19 to 28, wherein the amplifier circuit further includes a secondary amplifier circuit. The secondary amplifier circuit is a non-inverting negative feedback amplifier circuit and has an operational amplifier OP3, a feedback resistor R4, a resistor R5, and a capacitor C2. The output terminal of the operational amplifier OP3 is connected to the inverting input terminal of the operational amplifier OP3 through the feedback resistor R4. The non-inverting input terminal of the operational amplifier OP3 is electrically connected to the output terminal of the operational amplifier OP1 of the primary amplifier circuit 31. The inverting input terminal of the operational amplifier OP3 is further grounded for AC through the resistor R5 and the capacitor C2 connected in series.

33. The amplifier circuit capable of shortening the power-on time according to claim 32, wherein a DC bias voltage Vref3 is further connected to one end of the mutually series-connected resistor R5 and capacitor C2 that is grounded for AC, and the difference between the DC bias voltage Vref3 and the DC bias voltage Vrefin connected to the non-inverting input terminal of the operational amplifier OP1 tends to be the same within a range of less than or equal to 0.5V.

34. The amplifier circuit capable of shortening the power-on time according to claim 33, wherein the DC bias voltage Vref3 is set to be the same as the DC bias voltage Vref1.

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