TWI382662B - Pir detector and control method thereof - Google Patents

Description

Pyroelectric type infrared detector and control method thereof

This case is about a pyroelectric type infrared detector, especially the control circuit of the pyroelectric type infrared detector.

In view of the current awareness of environmental protection, the demand for energy-saving sensing devices is also growing. At present, the most common light source automatic control device on the market is such as Pyroelectric Infrared Sensor (PIR); this device is generally suitable for home, office, public places, etc., and the focus type infrared detection The device itself is used to detect infrared light from the human body, which in turn triggers the luminaire or security system.

In general, the position of the pyroelectric infrared detector is usually at a high position or no mains supply, and the power used by the detector is often a battery, so the power consumption of the detector itself is relatively important. . The average power consumption required for the control IC of the pyroelectric type infrared detector is generally 100uA to 500uA. If the average power consumption per battery is 1A/h, the average power consumption is 100uA. It can be used for about 1 year in standby mode. It can be seen that if the average power consumption of the control IC can be reduced, the user can be brought longer.

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

As shown in the first figure, it is a circuit block diagram of a conventional pyroelectric type infrared detector. As shown in the first figure, the pyroelectric type infrared detector 1 is mainly composed of a control integrated circuit (IC) 10, a photosensitive (CDS) detecting circuit 11, a low voltage detecting circuit 12, and a buzzer 13. The pyroelectric type infrared detector 1 uses the CDS detection circuit 11 to detect the environment to determine whether the surroundings are day or night. When it is detected that it is daytime, the control IC 10 automatically turns off the focus type infrared detection. The digital circuit architecture in the detector 1 is designed to save power, but the analog amplifier and window comparator (not shown) are not turned off. This is because if the pyroelectric type infrared detector maintains the analog amplifier and the window type comparator in the open state, it can immediately reflect whether the signal is correct or valid if it is detected at night. Conversely, if the analog amplifier and the window comparator are turned off, the pyroelectric infrared detector takes a long time to restart the analog amplifier.

On the other hand, it can be seen from the first figure that the conventional pyroelectric type infrared detector uses the resistor voltage division method for the battery power Vcc in the low voltage detecting circuit 12 for power source detection. Detection; however, although the resistance is relatively large, although the power is relatively low, the signal is susceptible to interference, and the low voltage detection circuit 12 is easily accidentally activated.

Therefore, it is necessary to conceive a pyroelectric type infrared detector. It is best to use only the three pins of the control IC to perform functions such as CDS detection, low voltage detection and buzzer call (traditional practice such as first As shown in the figure, at least four pins are required, and it is desirable to consume less electricity than conventional methods.

According to the above concept, the present invention proposes a pyroelectric type infrared detector controlled by a battery power, comprising: a control integrated circuit (IC) having at least one analog amplifier therein, the control integrated circuit having a first One end, a second end and a third end; a photosensitive (CDS) detecting circuit, wherein at least one photoresistor and a resistor are connected in series with each other, one end of the photo detecting circuit is controlled by the battery power, and One end is electrically connected to the first end of the control integrated circuit for detecting whether the environment in which the pyroelectric infrared detector is located is daylight; and a low voltage detecting circuit is connected in series by at least two resistors The one end of the low voltage detecting circuit is controlled by the battery power, and the other end is electrically connected to the end of the photo detecting circuit and the control integrated circuit electrically connected to detect whether the battery power is too low. And a buzzer, one end is electrically connected to the second end of the control integrated circuit via a series voltage dividing node in the photosensitive detecting circuit, and the other end is connected through a series in the low voltage detecting circuit The node is electrically connected to the third end of the control integrated circuit; wherein, when the photosensitive detecting circuit detects that the environment in which the pyroelectric infrared detector is located is daytime, the control integrated circuit turns off the Analog amplifier to save the battery power, when the photodetection circuit detects that the environment of the pyroelectric infrared detector is not daytime, the control integrated circuit turns on the analog amplifier, and when the low voltage detection When the circuit detects that the battery power is too low, the control integrated circuit turns on the buzzer to notify the user.

According to the above concept, another aspect of the present invention provides a control method for a pyroelectric type infrared detector, the focus type infrared detector comprising at least a battery, a photosensitive (CDS) detecting circuit and a low voltage detecting circuit. The control method includes the following steps: when the photodetection circuit detects that the environment in which the pyroelectric infrared detector is located is daytime, saving the power of the pyroelectric type infrared detector controlled by the battery; The low voltage detecting circuit notifies the user of the pyroelectric type infrared detector when the power of the battery is too low; and when the light detecting circuit detects or when the low voltage detecting circuit detects During the measurement, the pyroelectric infrared detector is stopped for infrared detection. This case can be further understood by the following diagrams and detailed explanations:

Please refer to the second figure, which is a circuit block diagram of a preferred embodiment of the pyroelectric type infrared detector proposed in the present application. In the second figure, the pyroelectric type infrared detector 2 is controlled by a battery power Vcc, and the pyroelectric type infrared detector 2 is mainly controlled by a control integrated circuit (IC) 20 and a photosensitive (CDS). The measuring circuit 21, a low voltage (LVD) detecting circuit 22 and a buzzer 23 are formed.

The control integrated circuit (IC) 20 has at least one analog amplifier (not shown) therein, and the control integrated circuit 20 has a first terminal T1, a second terminal T2 and a third terminal T3. The following describes the connection method of the three endpoints separately.

The photosensitive (CDS) detecting circuit 21 is composed of at least one photoresistor and a resistor connected in series with each other. One end of the photo detecting circuit 21 is controlled by the battery power Vcc, and the other end is electrically connected to the first of the control integrated circuit 20. The terminal T1 is configured to detect whether the environment in which the pyroelectric infrared detector 2 is located is daytime.

The low voltage detecting circuit 22 is formed by connecting at least two resistors in series. One end of the low voltage detecting circuit 22 is controlled by the battery power Vcc, and the other end is electrically connected to the photosensitive detecting circuit 21 and the control integrated circuit 20 to be electrically connected to each other. The connected end 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 via a series voltage dividing node in the photosensitive detecting circuit 21, and the other end is connected in series through the low voltage detecting circuit. The voltage dividing node is electrically connected to the third end LVD/BUZ of the control integrated circuit.

The operation of the pyroelectric type infrared detector 2 is such that when the photosensitive detecting circuit 21 detects that the environment in which the pyroelectric type infrared detector 2 is located is daytime, the control integrated circuit 20 turns off the analog amplifier to save battery power. Vcc, when the photodetection circuit detects that the environment of the pyroelectric type infrared detector is not daytime, the control integrated circuit turns on the analog amplifier. When the low voltage detecting 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 be additionally electrically connected to the light emitting diode (LED) to cooperate with the 23 buzzer to notify the user.

The invention basically performs low voltage (LVD) detection and CDS detection by using only three-terminal pins in the control IC, and also includes a buzzer warning function, and adopts the three-terminal detection. Time-series detection; that is, the CDS detection of the second end T2 and the LVD detection of the third end T3 are determined by using the infrared ray (PIR) detection of the first end T1. That is, when the CDS detection of the second end T2 and the LVD detection of the third end T3 are performed, the PIR detection of the first end T1 is stopped; and when the PIR detection of the first end T1 is performed, Stop the CDS detection of the second end T2 and the LVD detection of the third end T3.

Therefore, not only can the power consumption be greatly reduced, but also the signal stability can be considered, and the system can still achieve the advantages of power saving and efficiency under environmental changes. In addition, the present invention performs low voltage detection in a fixed time period, so that the power consumption is only 1/50 of the conventional low voltage detection method; and when the buzzer is to be driven, it does not affect the external CDS and The LVD resistor circuit can therefore accurately reflect the warning sound without being affected.

Please refer to the third figure, which is a circuit block diagram of an embodiment of a control IC applied to the pyroelectric type infrared detector of the present invention. In the third figure, the control IC 30 further includes an infrared detecting circuit 40 for detecting the presence of the user. In the figure, the control IC 30 mainly uses the three-terminal pins 31, 32 and 34 for CDS detection, low voltage detection and buzzer call.

When the control IC 30 performs CDS detection and low voltage detection, the potential of the first terminal 34 is pulled low, so that the low voltage detection terminal LVD/BUZ and the CDS detection terminal CDS/BUZB measure the current voltage dividing resistor. Voltage level. In detail, if the CDS/BUZ potential is lower than the set level VL, the pyroelectric type infrared detector will know that the external environment is daytime. At this time, the control IC30 will turn off the analog amplifiers 38 and 39 to allow the pyroelectric type infrared detector. 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 type infrared detector will detect the low voltage, and the control IC The buzzer (not shown) is used to inform the user through the buzzer driver 33 to change the battery.

Regarding the time-sharing detection mechanism mentioned above, in the control IC 30 of the third figure, the switches S1 to S4 are used to achieve the second-end CDS detection and the third-end LVD detection and the infrared detection circuit 40. Time-sharing detection. In detail, when the CDS detection of the second end 31 and the LVD detection of the third end 32 are to be performed, the switches S3 and S4 are switched such that the first end 34 is disconnected from the comparators 35, 36, and The PIR detection of the first end 34 can be stopped; and when the PIR detection of the infrared detection circuit 40 is to be performed, the switches S3 and S4 are switched such that the second end 31 and the comparator 35 are disconnected, and the third The terminal 32 is disconnected from the comparator 36, and the CDS detection of the second terminal T2 and the LVD detection of the third terminal T3 can be stopped.

Please refer to the fourth figure, which is a flow chart of a preferred embodiment of the control method of the pyroelectric type infrared detector proposed in the present application. As shown in the fourth figure, after the power is turned on, the system then enters the pyroelectric infrared (PIR) fast heat engine to start. When performing infrared detection, it is mainly divided into photosensitive (CDS) detection and low voltage (LVD) detection. Two kinds.

When performing photo-sensing detection, when the photo-sensing circuit detects that the environment is daytime, the control IC then turns off the low-frequency amplifier; conversely, when the photo-sensing circuit detects that the environment is not daytime, the control IC immediately Turn on the low frequency amplifier.

On the other hand, when low voltage detection is performed, when the battery power is detected to be lower than the standard, the control IC starts the low voltage supply and activates the buzzer (or the light emitting diode) to notify the user to replace the battery.

In summary, the present invention mainly proposes a pyroelectric type infrared detector, which only needs to use the three pins of the control IC to complete functions such as CDS detection, low voltage detection and buzzer call, and energy consumption ratio. Traditionally, less electricity is available.

This case has been modified by people who are familiar with the art, but it is not intended to be protected by the scope of the patent application.

1. . . Pyroelectric infrared detector

10. . . Control IC

11. . . CDS detection circuit

12. . . Low voltage detection circuit

13. . . buzzer

2. . . Pyroelectric infrared detector

20. . . Control IC

twenty one. . . CDS detection circuit

twenty two. . . Low voltage detection circuit

twenty three. . . buzzer

30. . . Control IC

31. . . Second end

32. . . Third end

33. . . Buzzer driver

34. . . First end

35. . . Comparators

36. . . Comparators

37. . . Signal processor

38. . . Analog amplifier

39. . . Analog amplifier

40. . . Infrared detection circuit

T1. . . First end

T2. . . Second end

T3. . . Third end

S1 ~ S4. . . switch

The first picture: a circuit block diagram of a conventional pyroelectric type infrared detector.

Second: A block diagram of a preferred embodiment of a pyroelectric infrared detector proposed in the present application.

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

Fourth: A flow chart of a preferred embodiment of the control method of the pyroelectric type infrared detector proposed in the present application.

2. . . Pyroelectric infrared detector

20. . . Control IC

twenty one. . . CDS detection circuit

twenty two. . . Low voltage detection circuit

twenty three. . . buzzer

T1. . . First end

T2. . . Second end

T3. . . Third end

Claims (6)

A pyroelectric type infrared detector controlled by a battery power, comprising: a control integrated circuit (IC) having at least one analog amplifier therein, the control integrated circuit having a first end and a second end a third end; a photosensitive (CDS) detecting circuit, wherein at least one photoresistor and a resistor are connected in series with each other, one end of the photo detecting circuit is controlled by the battery power, and the other end is electrically connected to the control integrated body The first end of the circuit is configured to detect whether the environment in which the pyroelectric infrared detector is located is daylight; and a low voltage detecting circuit is formed by connecting at least two resistors in series, the low voltage detecting circuit One end is controlled by the battery power, and the other end is electrically connected to the end of the photo detecting circuit and the control integrated circuit electrically connected to detect whether the battery power is too low; and a buzzer, one end Connected to the second end of the control integrated circuit via a series voltage dividing node in the photosensitive detecting circuit, and the other end is electrically connected to the control via a series voltage dividing node in the low voltage detecting circuit Integrated electricity The third end; wherein, when the photodetection circuit detects that the environment in which the pyroelectric infrared detector is located is daytime, the control integrated circuit turns off the analog amplifier to save the battery power when the The light detecting type detecting circuit detects that the environment of the pyroelectric type infrared detecting device is not in the daytime, the control integrated circuit turns on the analog amplifier, and when the low voltage detecting circuit detects that the battery power is too low The control integrated circuit turns on the buzzer to notify the user. For example, the pyroelectric infrared detector of claim 1 further includes an infrared detecting circuit for detecting a user. For example, in the pyroelectric type infrared detector of claim 1, wherein the infrared detecting circuit stops infrared detecting when the photosensitive detecting circuit detects or when the low voltage detecting circuit detects . The pyroelectric type infrared detector of claim 1, wherein the buzzer is further electrically connected to a light emitting diode (LED) to cooperate with the buzzer to notify the user. A control method for a pyroelectric type infrared detector, the pyroelectric type infrared detector comprising at least one battery, a control integrated circuit (IC) having an analog amplifier, a photosensitive (CDS) detection circuit and a low The voltage detecting circuit includes the following steps: when the photosensitive detecting circuit detects that the environment of the pyroelectric infrared detector is daylight, the control integrated circuit turns off the analog amplifier to save the focus The electric infrared detector is controlled by the power of the battery; when the low voltage detection circuit detects that the power of the battery is too low, notifying the user of the pyroelectric infrared detector; and when the photosensitive detection The measuring circuit detects or stops the infrared type infrared detecting device to perform infrared detection when the low voltage detecting circuit detects. For example, the control method of claim 5 includes a step of: when the low voltage detecting circuit detects that the power of the battery is too low, visually or audibly notifying the pyroelectric type infrared detector. user.