阅读说明：本技术 热释电pir快速识别人体运动方向的方法及电路结构 (Method and circuit structure for rapidly identifying human motion direction by pyroelectric PIR ) 是由 黄小华 倪嘉辉 于 2020-07-30 设计创作，主要内容包括：本发明公开了一种热释电PIR快速识别人体运动方向的方法及电路结构,接收热释电PIR探测人体的感应信号,前置放大器将微弱的热释电电流转换为有效电压放大输出,并与基准电压进行比较,根据比较结果来判定人体运动方向。本发明能够在探测目标即人体进入防区初期,在热释电PIR产生抛物波输出人体信号时,通过比较器电路分离出基准电压,时长仅0.05-0.2秒,即可判定出人体运动方向,时效性和实用性大大提升,使得该方案真正能用于实践。(The invention discloses a method and a circuit structure for rapidly identifying the motion direction of a human body by pyroelectric PIRs, which are characterized in that an induction signal for detecting the human body by the pyroelectric PIRs is received, a preamplifier converts weak pyroelectric current into effective voltage for amplifying and outputting, and compares the effective voltage with reference voltage, and the motion direction of the human body is judged according to a comparison result. The invention can separate the reference voltage through the comparator circuit when the pyroelectric PIR generates parabolic waves to output human body signals at the initial stage of the detection target, namely the human body entering a defense area, the time duration is only 0.05-0.2 seconds, the motion direction of the human body can be judged, the timeliness and the practicability are greatly improved, and the scheme can be really used for practice.)

1. A method for rapidly identifying the motion direction of a human body by pyroelectric PIRs is characterized by comprising the following steps:

the device receives an induction signal of a human body detected by the pyroelectric PIR, the preamplifier converts the pyroelectric current into effective voltage for amplifying and outputting, and compares the effective voltage with reference voltage to judge the motion direction of the human body according to a comparison result.

2. The method for rapidly identifying the motion direction of the human body by the pyroelectric PIR as claimed in claim 1, wherein the method for determining the motion direction of the human body comprises:

determining the relation between the shape of a parabolic wave generated by the pyroelectric PIR and the motion direction of a human body;

when the comparison result exceeds the positive waveform reference voltage or is lower than the negative waveform reference voltage, determining that the human body moves; the moving direction is determined according to the above relationship.

3. The method for fast identification of human body motion direction by pyroelectric PIR according to claim 1, characterized in that the method for comparison comprises: comparing, using a waveform comparator, with a positive waveform reference voltage by a positive waveform comparator; comparing with a negative waveform reference voltage by a negative waveform comparator; the positive waveform comparator and the negative waveform comparator form partial voltage through two resistors and serve as reference voltage.

4. The method for fast distinguishing the moving direction of the human body by the pyroelectric PIR as claimed in claim 3, wherein the positive waveform comparator and the negative waveform comparator are connected in parallel to a resistor connected to the human body sensing signal.

5. The method for rapidly identifying the motion direction of the human body by the pyroelectric PIR as claimed in claim 1, wherein the reference voltage is selected by the following method: the value is taken between the voltage at the starting point when the human body enters the defense area and the voltage when the human body movement signal is strongest.

6. A circuit structure for the pyroelectric PIR to rapidly identify the human motion direction as claimed in any one of claims 1-5, characterized in that the circuit structure comprises a positive waveform comparator, a negative waveform comparator, and an access resistor for accessing the pyroelectric PIR to detect the human body sensing signal;

the access resistor is accessed to the positive input end of the positive waveform comparator, the first resistor and the second resistor form partial voltage, and the first resistor and the second resistor are accessed to the reverse input end of the positive waveform comparator to be used as positive waveform reference voltage;

the access resistor is simultaneously accessed to the reverse input end of the negative waveform comparator, the third resistor and the fourth resistor form partial voltage, and the third resistor and the fourth resistor are accessed to the positive input end of the negative waveform comparator to be used as negative waveform reference voltage;

the first resistor, the second resistor, the third resistor and the fourth resistor are connected in series.

7. The circuit structure of claim 6, wherein the access resistor is connected to a preamplifier, and the preamplifier converts the pyroelectric current into an effective voltage, amplifies and outputs the effective voltage to the access resistor.

Technical Field

The invention belongs to the field of intelligent detection of human motion direction, and particularly relates to a method and a circuit structure for rapidly identifying human motion direction by pyroelectric PIRs.

Background

For home life, doors and windows are entrances of a plurality of potential safety hazards, and the security of the doors and the windows is an important aspect about safety in smart homes. In the security protection of intelligent house, to present family window and door and window intelligence house demand, need know the specific direction of motion of the human body that surveys, for example whether open the door and come in or go out the door and go out the grade. In the prior art, the motion direction of a human body is identified through the polarity of a parabolic wave generated by pyroelectric PIRs, but in a conventional identification scheme, a specific direction can be identified only after the human body moves, for example, after a human body target sensing signal is detected and is processed by an amplifying circuit, judgment is started after the signal voltage rises from A to D through B, C in fig. 2, the judgment time needs 0.5-1 second, and the serious hysteresis exists.

Disclosure of Invention

The invention provides a method and a circuit structure for rapidly identifying the human motion direction by pyroelectric PIRs, which can judge the human motion direction in a short time and greatly improve the timeliness and the practicability.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for rapidly identifying the motion direction of a human body by pyroelectric PIRs (pyroelectric infrared detectors) comprises the following steps:

the device receives an induction signal of a human body detected by the pyroelectric PIR, the preamplifier converts the pyroelectric current into effective voltage for amplifying and outputting, and compares the effective voltage with reference voltage to judge the motion direction of the human body according to a comparison result.

Further, the method for determining the human body movement direction includes:

determining the relation between the shape of a parabolic wave generated by the pyroelectric PIR and the motion direction of a human body;

when the comparison result exceeds the positive waveform reference voltage or is lower than the negative waveform reference voltage, determining that the human body moves; the moving direction is determined according to the above relationship.

Further, the method of comparing comprises: comparing, using a waveform comparator, with a positive waveform reference voltage by a positive waveform comparator; comparing with a negative waveform reference voltage by a negative waveform comparator; the positive waveform comparator and the negative waveform comparator are divided by two resistors and used as respective reference voltages.

Furthermore, the positive waveform comparator and the negative waveform comparator are connected in parallel to a resistor connected with the human body induction signal.

Further, the value selection method of the reference voltage comprises the following steps: the value is taken between the voltage at the starting point when the human body enters the defense area and the voltage when the human body movement signal is strongest.

The invention also provides a circuit structure for rapidly identifying the human motion direction by the pyroelectric PIRs, which comprises a positive waveform comparator, a negative waveform comparator and an access resistor for receiving human induction signals detected by the pyroelectric PIRs;

the access resistor is accessed to the positive input end of the positive waveform comparator, the first resistor and the second resistor form partial voltage, and the first resistor and the second resistor are accessed to the reverse input end of the positive waveform comparator to be used as positive waveform reference voltage;

the access resistor is simultaneously accessed to the reverse input end of the negative waveform comparator, the third resistor and the fourth resistor form partial voltage, and the third resistor and the fourth resistor are accessed to the positive input end of the negative waveform comparator to be used as negative waveform reference voltage;

the first resistor, the second resistor, the third resistor and the fourth resistor are connected in series.

Furthermore, the access resistor is connected with a preamplifier, and the preamplifier converts the pyroelectric current into effective voltage to be amplified and output to the access resistor.

Compared with the prior art, the invention has the following beneficial effects:

the invention can separate the reference voltage through the comparator circuit when the pyroelectric PIR generates parabolic waves to output human body signals at the initial stage of the detection target, namely the human body entering a defense area, the time duration is only 0.05-0.2 seconds, the motion direction of the human body can be judged, the timeliness and the practicability are greatly improved, and the scheme can be really used for practice.

Drawings

FIG. 1 is a schematic diagram of a comparator circuit according to an embodiment of the present invention;

FIG. 2 is a waveform diagram illustrating forward motion of a detected object according to an embodiment of the present invention;

FIG. 3 is a waveform diagram of reverse motion of a detected object according to an embodiment of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The invention is further described with reference to the following figures and examples.

The principle of the pyroelectric infrared sensor is based on a pyroelectric sensor PIR, the pyroelectric sensor consists of a band-pass filter, an induction element and a shell, the infrared band-pass filter is 5-14um, covers the wavelength of 9um emitted by a human body and can only pass through, and infrared radiation outside the cut-off range of the infrared band-pass filter cannot pass through, so that the pyroelectric infrared sensor is high in anti-interference capability. The PIR internal structure is connected by a two-element ceramic sensor element through- + + -, if positive-then-negative parabolic waves are from left to right, then positive-then-negative-then-positive parabolic waves are from right to left, as can be seen in the parabolic wave shapes of fig. 2 and 3, respectively.

And the method is used for judging the in-and-out direction of the detection target according to the sequence of the two parabolic waves. Positive and negative parabolic waves are positive moving (incoming) waveforms, negative and positive parabolic waves are reverse moving (outgoing) waveforms, the general identification scheme is that when a human body moves, the parabolic waves appear to identify specific directions, and after a human body induction signal is processed by an amplifying circuit, as shown in fig. 2 or fig. 3, the parabolic wave at the point A, B, D forms a first half movement period and direction: the point A is the voltage of the starting point when the human body enters the defense area, the point C represents the voltage when the human body movement signal is strongest, and the point D is the zero voltage after the induction element releases electricity and releases charges. The whole movement period comprises a first half period and a second half period, the second half period is completed by the + -sensor, and the second half period can not participate in judgment; therefore, the conventional judgment method can judge the time length from A to D through C, wherein the time length is 0.5-1 second, but the time length of the conventional judgment method has serious hysteresis because the current requirement on the identification judgment speed is higher and higher.

The core idea of the invention is that a reference voltage B is selected between the point A and the point C of the parabolic wave, and the human body motion direction can be judged as long as the human body induction signal is judged to exceed the positive waveform reference voltage or be lower than the negative waveform reference voltage. The selection method of the reference voltage B is described by an embodiment, in the embodiment, the test environment is 25 degrees, the working voltage is 5V, the blackbody temperature is 420K (147 ℃), and the circuit amplification factor is 70 dB; when the normal human body walking speed is 0.6 m/s, a complete parabolic wave period detected by the pyroelectric sensor is 600 ms; as shown in FIG. 2, the X-axis is divided into 6 divisions of 100 mS.

The setting of the reference voltage depends on the required sensitivity, but also affects the alarm delay, and under the condition that the customer experience is not affected, the alarm signal can be controlled to be output within 200mS, in this embodiment, 100mS, that is, the voltage value at the end of the first cell is selected as the reference voltage, and then the positive waveform reference voltage is the central voltage 2.5V +0.5V (the voltage value increasing along with the parabolic slope) and is equal to 3V as shown in fig. 2; as shown in fig. 3, the reference voltage of negative waveform is that the central voltage is 2.5V-0.5V (the voltage value falling with the parabolic slope) is equal to 2V; the induction signal exceeds 3V and is a forward motion direction (in), and the induction signal is a reverse motion direction (out) below 2V.

After the human body enters the defense area, the movement direction can be judged at about 100mS at 1 lattice position on the X axis, and the judgment speed is greatly increased.

In the embodiment of the invention, the waveform comparator is adopted, the circuit structure of the waveform comparator is shown in fig. 1, the amplified human body induction signal is connected to the 3 pins of the positive input end of the positive waveform comparator by R9, R4 and R5 form a partial voltage which is used as the positive waveform reference voltage (namely B voltage of fig. 2) of the 2-pin positive waveform comparator, when the 3-pin input voltage exceeds the 2-pin reference voltage and + H outputs high level, if the voltage is firstly increased, the direction of the incoming user is identified.

The R9 is simultaneously connected to the other set of 13 pins of the negative waveform comparator with 13 pins, the R13 and R14 form a divided voltage as the negative waveform reference voltage (i.e. the voltage B in fig. 3) of the negative waveform comparator with 12 pins, when the input voltage with 13 pins is lower than the voltage with 12 pins, the output voltage is high, and if the voltage is high first, the direction of the user going out is identified.

The diagram of the forward movement waveform of the detected target is shown in fig. 2, wherein a parabola is a target (human body) induction voltage, and a square wave is a comparator output voltage; when a detection target (human body) enters a defense area, a positive parabolic wave point A signal is strengthened, when the voltage is higher than a positive waveform reference voltage at a point B, the proportional comparator circuit is turned over, and at the moment, a positive high level + H is separated, if the voltage appears first, the human body can be judged to move in a positive direction, such as the incoming direction.

The diagram of the waveform of the detected target moving reversely is shown in fig. 3, wherein the parabola is the human body induction voltage, and the square wave is the output voltage of the comparator; when a detection target (human body) enters a defense area, a signal of a negative parabolic wave point A is strengthened, when the voltage is lower than a negative waveform reference voltage of a point B, the negative wave comparator is turned over, and then a reverse high level-H is separated, if the voltage appears first, the human body can be judged to move reversely, for example, the direction of going out.

As can be seen from the figure, the time A-B is short, the time lag is short, the experience is good, and the intelligent household appliance can be widely applied to the field of intelligent household. The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.