CN101900837A - Pyroelectric infrared detector and its control method - Google Patents

Abstract

The invention provides a pyroelectric infrared detector and a control method thereof, wherein the pyroelectric infrared detector is controlled by battery power and comprises the following steps: a control Integrated Circuit , a photo-sensing (CDS) detection circuit, a low voltage detection circuit and a buzzer; when the photosensitive detection circuit detects that the environment of the pyroelectric infrared detector is daytime, the control integrated circuit turns off an analog amplifier in the pyroelectric infrared detector to save the power of the battery, and when the photosensitive detection circuit detects that the environment of the pyroelectric infrared detector is not daytime, the control integrated circuit turns on the analog amplifier; when the low voltage detection circuit detects that the battery power is too low, the control integrated circuit turns on the buzzer to inform a user.

Description

Pyroelectric infrared detector and its control method

technical field

The invention relates to a pyroelectric infrared detector, in particular to a control circuit of the pyroelectric infrared detector.

Background technique

In view of the increasing awareness of environmental protection, the demand for energy-saving sensing devices is also increasing. At present, the most common light source automatic control devices on the market are mostly pyroelectric infrared detectors (Pyroelectric Infrared Sensor, PIR); this device is generally applicable to homes, offices, public places, etc., and pyroelectric infrared detector The device itself is used to detect human infrared rays, and then trigger lamps or security systems.

Generally speaking, the location where the pyroelectric infrared detector is erected is usually at a high place or where there is no mains power supply, and the power source used by the detector is usually a battery, so the power consumption of the detector itself is relatively low. important. The average power consumption required by the control IC of the pyroelectric infrared detector generally ranges from 100uA to 500uA. If the average power consumption of each battery is 1A/h, the average power consumption of the 100uA It can be used for about 1 year in standby mode. It can be seen from this that if the average power consumption of the control IC can be reduced, it will bring users a longer usage time.

On the other hand, if the control IC of the pyroelectric infrared detector itself needs to perform multiple detection functions (such as: brightness detection or low voltage detection), the existing control IC of the pyroelectric infrared detector The number of required package pins will become quite large. Therefore, the cost of IC design and packaging is also increased, and the design area of the circuit is relatively increased.

As shown in FIG. 1 , it is a circuit block diagram of a conventional pyroelectric infrared detector. As shown in FIG. 1 , the pyroelectric infrared detector 1 is mainly composed of a control integrated circuit (IC) 10 , a photosensitive (CDS) detection circuit 11 , a low voltage detection circuit 12 and a buzzer 13 . The pyroelectric infrared detector 1 uses the CDS detection circuit 11 to detect the environment to determine whether it is day or night around; when it is detected that it is daytime, the control IC 10 will automatically turn off the pyroelectric infrared detector. The digital circuit architecture in the tester 1 is used to save power, but the analog amplifier and window comparator (not shown in the figure) will not be turned off. This is because if the pyroelectric infrared detector keeps the analog amplifier and window comparator in the open state, if it detects that it is night, it can immediately reflect whether the signal is correct or valid. On the contrary, if the analog amplifier and the window comparator are turned off, the pyroelectric infrared detector needs a long time to restart the analog amplifier.

On the other hand, it can also be seen from FIG. 1 that in the low-voltage detection circuit 12 used for power detection in the existing pyroelectric infrared detectors, most of them adopt the method of resistor voltage division to monitor the battery power Vcc. detection; however, although the resistance of the resistance is large, although the power is saved, the signal is easily disturbed, so that the low voltage detection circuit 12 is easily activated by mistake.

Contents of the invention

Therefore, it is necessary to propose a pyroelectric infrared detector. It is best to use only three pins of the control IC to complete the functions of CDS detection, low voltage detection and buzzer call (the traditional method is shown in the figure 1 generally requires a minimum of four pins), and it is hoped that the power consumption will be less than the traditional practice.

According to the above idea, the present invention proposes a pyroelectric infrared detector controlled by a battery power, including: a control integrated circuit (IC) with at least one analog amplifier inside, and the control integrated circuit has a first One terminal, a second terminal and a third terminal; a photosensitive (CDS) detection circuit, composed of at least one photosensitive resistor and a resistor in series with each other, one end of the photosensitive detection circuit is controlled by the battery power, and the other One end is electrically connected to the first end of the control integrated circuit to detect whether the environment where the pyroelectric infrared detector is located is daytime; a low voltage detection circuit is composed of at least two resistors connected in series , one end of the low-voltage detection circuit is controlled by the battery power, and the other end is electrically connected to the end where the photosensitive detection circuit and the control integrated circuit are electrically connected to each other, so as to detect whether the battery power is too low; and A buzzer, one end of which is electrically connected to the second end of the control integrated circuit through a series voltage dividing node in the photosensitive detection circuit, and the other end is electrically connected to the second end of the control integrated circuit through a series voltage dividing node in the low voltage detection circuit Electrically connected to the third end of the control integrated circuit; wherein, when the photosensitive detection circuit detects that the environment of the pyroelectric infrared detector is daytime, the control integrated circuit turns off the analog amplifier to save The battery power, when the photosensitive detection circuit detects that the environment where the pyroelectric infrared detector is located is not daytime, the control integrated circuit turns on the analog amplifier, and when the low voltage detection circuit detects that the When the battery power is too low, the control integrated circuit turns on the buzzer to notify the user.

According to the above idea, another aspect of the present invention proposes a control method of a pyroelectric infrared detector, which at least includes a battery, a photosensitive (CDS) detection circuit and a low voltage detection circuit, the control method includes the following steps: when the photosensitive detection circuit detects that the environment in which the pyroelectric infrared detector is located is daytime, saving the electric power of the pyroelectric infrared detector controlled by the battery ; When the low voltage detection circuit detects that the power of the battery is too low, notify the user of the pyroelectric infrared detector; and when the photosensitive detection circuit detects or when the low voltage detection circuit When detecting, stop the pyroelectric infrared detector for infrared detection. The present invention will be described in more detail in conjunction with the following drawings:

Description of drawings

Fig. 1 is a kind of circuit block diagram of existing pyroelectric type infrared detector;

Fig. 2 is a circuit block diagram of a preferred embodiment of the pyroelectric infrared detector proposed by the present invention;

Fig. 3 is a circuit block diagram of an embodiment of the control IC applied to the pyroelectric infrared detector of the present invention;

FIG. 4 is a flow chart of a preferred embodiment of the control method of the pyroelectric infrared detector proposed by the present invention.

Detailed ways

Please refer to FIG. 2 , which is a circuit block diagram of a preferred embodiment of the pyroelectric infrared detector proposed by the present invention. In Fig. 2, the pyroelectric infrared detector 2 is controlled by a battery power Vcc, and the pyroelectric infrared detector 2 is mainly composed of a control integrated circuit (IC) 20, a photosensitive (CDS) detection circuit 21. Consists of a low voltage (LVD) detection circuit 22 and a buzzer 23.

There is at least one analog amplifier (not shown) inside the control integrated circuit (IC) 20 , and the control integrated circuit 20 has a first terminal T1 , a second terminal T2 and a third terminal T3 . The connection methods of the three endpoints are described below.

A photosensitive (CDS) detection circuit 21 is composed of at least one photosensitive resistor and a resistor connected in series. One end of the photosensitive detection circuit 21 is controlled by the battery power Vcc, and the other end is electrically connected to the first end of the control integrated circuit 20. T1 is used to detect whether the environment where the pyroelectric infrared detector 2 is located is daytime.

The low-voltage detection circuit 22 is composed of at least two resistors connected in series. One end of the low-voltage detection circuit 22 is controlled by the battery power Vcc, and the other end is electrically connected to the photosensitive detection circuit 21 and the control integrated circuit 20. The end of the battery is used to detect whether the battery power Vcc is too low.

One end of the buzzer 23 is electrically connected to the second end CDS/BUZB of the control integrated circuit 20 through a series voltage divider node in the photosensitive detection circuit 21, and the other end is electrically connected to the second end CDS/BUZB of the control integrated circuit 20 through a series divider node in the low voltage detection circuit. The voltage node is electrically connected to the third terminal LVD/BUZ of the control integrated circuit.

The execution process of the pyroelectric infrared detector 2 is that when the photosensitive detection circuit 21 detects that the environment where the pyroelectric infrared detector 2 is located is daytime, the control integrated circuit 20 turns off the analog amplifier to save battery power Vcc, when the photosensitive detection circuit detects that the environment where the pyroelectric infrared detector is located is not daytime, the control integrated circuit turns on the analog amplifier. And when the low voltage detection circuit detects that the battery power is too low, the control integrated circuit turns on the buzzer to notify the user.

Of course, the buzzer 23 can also be additionally electrically connected to a light emitting diode (LED), so as to cooperate with the buzzer 23 to notify the user.

The present invention basically uses only three-terminal pins in the control IC to perform low-voltage (LVD) detection and CDS detection, and also includes a buzzer warning function, and uses three-terminal detection Time-sharing detection; that is, the CDS detection of the second terminal T2 and the LVD detection of the third terminal T3 are time-sharing judgments with the infrared (PIR) detection of the first terminal T1. That is to say, when the CDS detection of the second terminal T2 and the LVD detection of the third terminal T3 are performed, the PIR detection of the first terminal T1 is stopped; and when the PIR detection of the first terminal T1 is performed, then The CDS detection of the second terminal T2 and the LVD detection of the third terminal T3 are stopped.

Therefore, not only the power consumption can be greatly reduced and the signal stability can be taken into consideration, but also the advantages of power saving and performance can still be taken into account when the system changes in the environment. In addition, the present invention can also perform low-voltage detection within a fixed time, so that the power consumption is only 1/50 of the traditional low-voltage detection method; and when the buzzer is to be driven, it will not affect the external CDS With the LVD resistor circuit, it can indeed reflect the warning sound without being affected.

Please refer to FIG. 3 , which is a circuit block diagram of an embodiment of a control IC applied to the pyroelectric infrared detector of the present invention. In FIG. 3, the control IC 30 also includes an infrared detection circuit 40, and two groups of analog amplifiers each composed of an amplifier 38 or 39, resistors R1 and R2, and capacitors C1 and C2, which work together to detect users. appear. In this figure, the control IC 30 mainly uses the three-terminal pins 31 , 32 and 34 to perform functions such as CDS detection, low voltage detection and buzzer calling.

When the control IC 30 performs CDS detection and low-voltage detection, it will pull down the potential of the first terminal 34, so that the low-voltage detection terminal LVD/BUZ and CDS detection terminal CDS/BUZB can measure the voltage behind the current divider resistor. voltage level. Specifically, if the CDS/BUZ potential is lower than the set level VL, the pyroelectric infrared detector will know that the external environment is daytime, and at this time, the control IC 30 will turn off the analog amplifiers 38 and 39 to allow the pyroelectric infrared rays The detector has lower power consumption; on the other hand, if the potential of the low voltage detection terminal LVD/BUZ is lower than the set level VH, the pyroelectric infrared detector will detect low voltage, and at this time The control IC will use the buzzer (not shown in the figure) through the buzzer driver 33 to notify the user that the battery needs to be replaced.

Regarding the above-mentioned time-division detection mechanism, in the control IC 30 in FIG. 3 , the signal processor 37 controls the switches S1-S4 to achieve the CDS detection at the second end and the LVD detection and infrared detection at the third end. Time-division detection between detection circuits 40. Specifically, when the CDS detection of the second terminal 31 and the LVD detection of the third terminal 32 are to be performed, the signal processor 37 switches the switches S3 and S4 so that the first terminal 34 and the comparators 35, 36 are interrupted. open, and can stop the PIR detection of the first end 34; and when the PIR detection of the infrared detection circuit 40 is to be performed, the signal processor 37 switches the switches S3 and S4 so that the second end 31 and the comparator 35 and the third terminal 32 and the comparator 36 are disconnected, so that the CDS detection of the second terminal T2 and the LVD detection of the third terminal T3 can be stopped.

Please refer to FIG. 4 , which is a flow chart of a preferred embodiment of the control method of the pyroelectric infrared detector proposed by the present invention. As shown in Figure 4, after the power is turned on, the system immediately enters into pyroelectric infrared (PIR) fast warm-up for infrared detection. When the aforementioned infrared detection is stopped, the detection performed at this time is mainly divided into two types: photosensitive (CDS) detection and low voltage (LVD) detection.

When performing photosensitive detection, when the photosensitive detection circuit detects that the environment is daytime, the control IC immediately turns off the low-frequency amplifier; on the contrary, when the photosensitive detection circuit detects that the environment is not daytime, the control IC immediately Turn on the low-frequency amplifier and perform CDS detection to determine whether the environment is day or night; when the environment is daytime, the low-frequency amplifier is turned off, and when the environment is night, the low-frequency amplifier is turned on.

On the other hand, when performing low voltage detection, when it is detected that the battery power is lower than the standard, the control IC starts the low voltage supply and starts the buzzer (or LED) to notify the user to replace the battery.

To sum up, the present invention mainly proposes a pyroelectric infrared detector, which only needs to use the three pins of the control IC to complete the functions of CDS detection, low voltage detection and buzzer call, and consumes less energy. Less electricity than traditional practice.

While the above examples describe the implementation of the present invention, various variations or modifications may be made by those skilled in the art within the scope of the appended claims. The scope of patent protection of the present invention must still be defined by the scope of the appended claims.

Claims (6)

1. a pyroelectric type infrared detector is controlled by a battery electric power, comprising:

One control integrated circuit, inside have at least one analogue amplifier, and this control integrated circuit has one first end, one second end and one the 3rd end;

One photosensitive circuit for detecting, constitute by at least one photoresistance and resistance institute that is one another in series, one end of this photosensitive circuit for detecting is controlled by this battery electric power, whether the other end is electrically connected on this first end of this control integrated circuit, be daytime in order to detect the residing environment of this pyroelectric type infrared detector;

One low-voltage circuit for detecting, by at least two resistance be one another in series the institute constitute, one end of this low-voltage circuit for detecting is controlled by this battery electric power, and whether the other end is electrically connected on that end that this photosensitive circuit for detecting and this control integrated circuit are electrically connected mutually, low excessively in order to detect this battery electric power; And

One hummer, one end is electrically connected on this second end of this control integrated circuit via the series connection dividing potential drop node of one in this photosensitive circuit for detecting, the other end is electrically connected on the 3rd end of this control integrated circuit via the series connection dividing potential drop node of one in this low-voltage circuit for detecting;

Wherein, when this photosensitive circuit for detecting detects the residing environment of this pyroelectric type infrared detector when being daytime, this control integrated circuit is closed this analogue amplifier to save this battery electric power, when this photosensitive circuit for detecting detects the residing environment of this pyroelectric type infrared detector when being not daytime, this control integrated circuit is opened this analogue amplifier, and cross when low when this low-voltage circuit for detecting detects this battery electric power, this control integrated circuit is opened this hummer to notify the user.

2. pyroelectric type infrared detector as claimed in claim 1 is characterized in that:

Also comprise a ultrared sensing circuit, in order to the detecting user.

3. pyroelectric type infrared detector as claimed in claim 1 is characterized in that:

Detect maybe when this low-voltage circuit for detecting is detected when this photosensitive circuit for detecting, this ultrared sensing circuit promptly stops to carry out ultrared sensing.

4. pyroelectric type infrared detector as claimed in claim 1 is characterized in that:

This hummer also is electrically connected on a light emitting diode, notifies the user to cooperate this hummer.

5. the control method of a pyroelectric type infrared detector, this pyroelectric type infrared detector comprises a battery, a photosensitive circuit for detecting and a low-voltage circuit for detecting at least, this control method comprises step:

When this photosensitive circuit for detecting detects the residing environment of this pyroelectric type infrared detector when being daytime, save the electric power that this pyroelectric type infrared detector is controlled by this battery;

The electric power that detects this battery when this low-voltage circuit for detecting is crossed when low, notifies the user of this pyroelectric type infrared detector; And

Detect maybe when this low-voltage circuit for detecting is detected when this photosensitive circuit for detecting, stop this pyroelectric type infrared detector and carry out ultrared sensing.

6. control method as claimed in claim 5 is characterized in that:

The electric power that detects this battery when this low-voltage circuit for detecting is crossed when low, utilizes visual manner or audible means to notify the user of this pyroelectric type infrared detector.

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