JP2002357668A - Abnormality detecting method for human body detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detecting method for human body detector capable of specifying the part where an abnormality is generated even in an all-in-one type human body detector. SOLUTION: In this abnormality detecting method for a PIR sensor A comprising a pyroelectric element 2 for detecting the change of an incident infrared energy and generating an electric signal according to the change quantity; an amplifier circuit 3 for amplifying the electric signal outputted from the pyroelectric element 2; a band filter 4 for removing an unnecessary frequency component from the output signal of the amplifier circuit 3 and outputting only a necessary signal; and a comparison circuit 5 for comparing the output of the band filter 4 with a prescribed threshold, a signal processing part 10 judges the generation of an abnormality in the PIR sensor A when the frequency that the output voltage S1 of the amplifier circuit 3 exceeds a prescribed threshold voltage while the output voltage S1 is stabilized in the state where the power source voltage of the PIR sensor A is lowered to 0 V only for a prescribed time and then raised to steady voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a human body detector.

[0002]

2. Description of the Related Art Conventionally, there has been provided an alarm device which detects an intruder who has entered a predetermined area, turns on a lighting load, and issues an alarm such as a buzzer or a siren.
In such an alarm device, a human body detector including a pyroelectric infrared sensor is used to detect an intruder.

In this type of human body detector, infrared light from a detection area is incident on a pyroelectric element via a light receiving optical system, and a change in infrared energy detected by the pyroelectric element is amplified by an amplification section. Is compared with a predetermined threshold value by the comparison unit to detect the presence or absence of a person in the detection area.

[0004]

Generally, in a system such as an alarm device incorporating a human body detector, inspection such as disconnection detection is performed, but abnormality detection of the human body detector itself is not performed. Therefore, if there is an abnormality in a component of the human body detector (for example, a pyroelectric element, or a circuit component constituting the amplification unit and the comparison unit), an erroneous or unreported error continues for an extremely long time. However, there is no other way than to predict the abnormality of the human body detector, and it is impossible to specify which part of the human body detector has the abnormality.

Although it is possible to determine the abnormality of a certain part from the output of the amplifier, the circuit constituting the human body detector is housed in a package such as CAN.
In an all-in-one type human body detector capable of performing signal processing only on the output of the comparison unit, the output of the amplification unit cannot be taken out, so that there is a problem that an abnormality cannot be detected from the output of the amplification unit.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an all-in-one type human body detector which can identify a portion where an abnormality has occurred. It is to provide a detection method.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a sensor unit for generating an electric signal having a magnitude corresponding to a change in infrared energy radiated from a human body; In the abnormality detection method for a human body detector including an amplification unit that amplifies an electric signal generated by the unit, the power supply voltage is reduced for a predetermined time to a predetermined voltage at which the voltage of each unit is sufficiently discharged, and then a steady state is performed. When the number of times the output voltage exceeds a predetermined threshold voltage is different from the normal state until the output voltage of the amplifying section is stabilized in the state where the voltage has been restored to If the output voltage exceeds the threshold voltage until the output voltage of the amplifier section becomes stable, the number of times that the output voltage exceeds the threshold voltage is different from the normal state. Determine Rukoto can. In addition, a comparison unit that compares the level of the output voltage of the amplification unit and the threshold voltage,
Even in an all-in-one type human body detector that can take out only this output, by detecting the number of times the output of the comparison unit is inverted, the number of times that the output voltage of the amplification unit exceeds the threshold voltage can be detected. An abnormal state can be determined from the above.

According to a second aspect of the present invention, in the first aspect of the present invention, when the number of times is smaller than the normal time, it is determined that the output is abnormal. In the event of an abnormality such that the gain of the amplifier becomes smaller than normal, if the power supply voltage is temporarily lowered and then restored, the output voltage of the amplifier will become the threshold voltage until the output voltage becomes stable. Since the number of times exceeding the number of times is smaller than that in the normal state, an abnormal state can be determined by detecting the number of times.

According to a third aspect of the present invention, in the first aspect of the present invention, when the number of times is larger than the normal time, it is determined that the abnormality is abnormal. At the time of occurrence, if the power supply voltage is temporarily lowered and then restored, the number of times that the output voltage exceeds the threshold voltage until the output voltage of the amplifier section becomes stable will be larger than in the normal case. By detecting, an abnormal state can be determined.

According to a fourth aspect of the present invention, there is provided a sensor unit for generating an electric signal having a magnitude corresponding to a change in infrared energy radiated from a human body, and an amplifying unit for amplifying the electric signal generated by the sensor unit. In the abnormality detection method of the human body detector, the power supply voltage is reduced to a predetermined voltage or less at which the voltage of each part is sufficiently discharged for a predetermined time, and then the output voltage of the amplification unit is restored to a voltage at a steady state. If the number of times the output voltage exceeds a predetermined threshold voltage during a certain period after the stabilization is different from the normal state, it is determined to be abnormal, and when the power supply voltage is temporarily lowered and then restored, Since the number of times that the output voltage exceeds the threshold voltage during a certain period after the output voltage of the amplifying section has stabilized is different from the normal state, an abnormal state can be determined by detecting this number.
In addition, the all-in-one type human body detector that has a comparison unit that compares the output voltage of the amplifying unit with the threshold voltage and detects only this output can detect the number of times the output of the comparison unit is inverted. Accordingly, the number of times that the output voltage of the amplifier exceeds the threshold voltage can be detected, and an abnormal state can be determined from the number of times.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, when the number of times is greater than a normal time, it is determined that there is an abnormality. Since the output voltage of the amplifying unit is stabilized after the output voltage of the amplifier unit is stabilized, the number of times that the output voltage exceeds the threshold voltage is larger than that in the normal state. By detecting the number of times, the abnormality of the sensor unit is determined. can do.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the abnormality detecting operation is periodically performed, and the abnormality detecting operation is periodically performed to quickly detect an abnormality of the human body detector. Can be detected.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, at the timing of performing the abnormality detecting operation, the sensor detects infrared rays radiated from a human body, and determines that the output voltage of the amplifier is equal to or higher than the threshold voltage. If the number of times is equal to or more than a predetermined number of times, the output voltage of the amplifying unit exceeds the threshold voltage during the detection of a human body, characterized by shifting the timing of performing the abnormality detection operation for a certain period of time required for the output voltage to stabilize. If the abnormality detection operation is performed in this state, there is a possibility that the abnormal state is erroneously detected.However, the number of times that the sensor unit detects infrared rays emitted from the human body and the output voltage of the amplifier unit is equal to or higher than the threshold voltage is equal to or more than the predetermined number In this case, since the timing of performing the abnormality detection operation is determined to be different from the time of detecting the human body, it is possible to prevent the detection of the human body from being erroneously detected as an abnormal state.

According to an eighth aspect of the present invention, in the first to fifth aspects of the present invention, the detection signal generated by the human body detector is provided until a predetermined time elapses after the human body detector once generates the human body detection signal. Is characterized by providing an off-delay period in which the error is ignored, and performing an abnormality detection operation during the off-delay period. Since the power supply voltage is instantaneously stopped to detect the abnormality, there is a possibility that the human body may be unreported during this period. However, during the off-delay period, the human body detection signal generated by the human body detector may be ignored.
There is no unreporting during the abnormality detection operation, and the occurrence of a malfunction can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An infrared passive sensor (hereinafter referred to as P) as a human body detector to which the abnormality detection method according to the present invention is applied.
FIG. 1 shows a block diagram of an IR sensor). This P
The IR sensor A is an optical lens unit 1 that focuses infrared rays radiated from a human body in a predetermined detection area on the pyroelectric element 2.
A pyroelectric element 2 for detecting a change in incident infrared energy and generating an electric signal having a magnitude corresponding to the change amount; and an amplifying circuit 3 for amplifying an electric signal output from the pyroelectric element 2
A bandpass filter 4 that removes unnecessary frequency components from the output signal of the amplifier circuit 3 and outputs only necessary signals, and a comparison circuit 5 that compares the output of the bandpass filter 4 with a predetermined threshold. Is done. Then, in the signal processing unit 10,
After reducing the power supply voltage of the PIR sensor A for a predetermined time and then returning to the steady state voltage, the abnormality of the PIR sensor A is detected from the waveform of the output voltage S2 of the comparison circuit 5. Here, FIG. 2 is a specific circuit diagram of the PIR sensor A in which the amplification circuit 3 is configured by a two-stage amplifier.
, Rf1,... And capacitors Cs1,..., Cf1,.

FIG. 3 is a block diagram of an all-in-one type PIR sensor A. In this PIR sensor A, a pyroelectric element 2, an amplifier 3, a bandpass filter 4, and a comparator 5
Are housed inside the CAN 6, and only the output voltage S2 of the comparison circuit 5 can be taken out. FIG.
Is an example of an amplifier circuit 3 used in an all-in-one type PIR sensor A. The amplifier circuit 3 having a zero point correction function using an integrating circuit is composed of operational amplifiers OP3 to OP6, resistors R1 to R4, and capacitors C1 and C2. Make up.

Here, the output voltages S1 and S2 of the amplifier circuit 3 and the comparison circuit 5 depend on whether the PIR sensor A is normal or abnormal.
Will be described with reference to FIGS. 5 to 7. FIG. In this embodiment, the output voltage of the bandpass filter 4 is detected as the output voltage S1 of the amplifier circuit 3.

FIG. 5A is a waveform diagram of the output voltage S1 of the amplifier circuit 3 in a normal state, and FIG. 5B is a waveform diagram of the output voltage S2 of the comparison circuit 5 in a normal state. After passing through the detection area, the output voltages S1, S
2 vibrates greatly.

On the other hand, FIGS. 6 (a) and 6 (b) are waveform diagrams in the case where an abnormality such as cracking or breakage occurs in the pyroelectric element 2 (hereinafter, an abnormality of the pyroelectric element 2 is referred to as an abnormality of the case 1). 6A shows a waveform diagram of the output voltage S1, and FIG. 6B shows a waveform diagram of the output voltage S2. In this case, even if no person has passed through the detection area, the pyroelectric element 2
, The output voltages S1 and S2 greatly oscillate.

Further, when an abnormality occurs in a capacitor, a resistor, or the like constituting the high-pass filter (hereinafter, an abnormality in the high-pass filter, that is, an abnormality relating to a transient response of the output voltage S1 is referred to as an abnormality in Case 2), that is, FIG.
In the circuit shown in FIG.
Either s1 or Rs2 is open or the capacitor C1 and the resistor R in the circuit shown in FIG.
When any one of R3 and R4 is in the open state, the output voltage S2 of the comparison circuit 5 does not become high (ON) even when a person passes through the detection area, and the steady noise is lower than that in the normal state. It becomes small and almost zero.

Further, in the circuit shown in FIG.
4 is in an open state, or when the capacitor C2 is in an open state in the circuit shown in FIG. 4 (such an abnormality is called an abnormality in Case 3), the amplification circuit 3 is interrupted on the way, so that the detection area cannot be changed. , The person cannot be detected, and the steady-state noise is smaller than normal and becomes substantially zero.

FIGS. 7A and 7B show a case where an abnormality occurs in the resistance constituting the feedback section of the amplifier circuit 3 (hereinafter, an abnormality of the feedback section is referred to as an abnormality of the case 4), that is, FIG. In the circuit shown in FIG.
FIGS. 7A and 7B are waveform diagrams when one of R2 is in an open state, and FIG. 7A is a waveform diagram of the output voltage S1, and FIG. 7B is a waveform diagram of the output voltage S2. In this case, when a person passes through the detection area during the period Tb, the output voltages S1 and S2 of the amplification circuit 3 and the comparison circuit 5 vibrate, and the human body is detected. Also, the output voltages S1 and S2 of the amplification circuit 3 and the comparison circuit 5 oscillate even when there is no person in the detection area (a period other than the period Tb). Note that any component that is assumed to be abnormal here is a component that is likely to perform an abnormal operation when an abnormality occurs.

Here, there is a demand to determine the abnormality in each case described above, but the output voltage S1 of the amplifier circuit 3 when a human body is detected in a normal state (see FIG. 5A).
And the output voltage S1 (see FIG. 6A) of the amplifier circuit 3 at the time of occurrence of the abnormality in Case 1, resulting in a similar voltage waveform. It is.

When the cases 2 and 3 are abnormal, the output voltage S1 of the amplifier circuit 3 is a normal noise level (approximately 0.1 to 0. 0) because the amplifier circuit 3 is interrupted halfway. 2V), which is extremely small, about 0.01 V, so that an abnormal state can be detected from the voltage level of the output voltage S1. However, when only the output voltage S2 of the comparison circuit 5 can be extracted, Since the output voltage S2 of the comparison circuit 5 is not different from that in the normal state, there is a problem that an abnormal state cannot be detected until it is found that a human body is not detected in spite of the presence of a person in the detection area.

Further, when the case 4 is abnormal, the human body can be detected. However, since the gain of the amplifier circuit 3 is increased, the stationary noise is increased even when the human body is not detected, and a malfunction occurs. In addition, since it is not possible to perform a method of determining whether the output signal of the amplifier circuit 3 is equal to or less than a predetermined value as in the case of the above-described cases 2 and 3, an abnormal state cannot be detected.

Therefore, in the abnormality detection method according to the present invention,
Set the power supply voltage of the PIR sensor A to a predetermined time (for example, about 1 second)
However, after the voltage of each unit is reduced to a predetermined voltage or less (for example, 0 V in the present embodiment) at which the voltage is sufficiently discharged (instantaneous stop), the signal processing unit 10 restores the voltage to the steady state by the comparison circuit. 5, the abnormality of the PIR sensor A is detected.

When the power supply voltage of the PIR sensor A is varied as described above, the waveforms of the output voltage S1 of the amplifier circuit 3 and the output voltage S2 of the comparison circuit 5 at normal times and at the time of occurrence of an abnormality in the cases 1-4. Figures are shown in FIGS.
8 to 12 show output voltages S1 and S2 of the amplifier circuit 3 and the comparison circuit 5 when the power supply voltage is restored after the power supply voltage is stopped at 0 V in the periods T1 to T5, respectively.

At this time, the output voltage S2 of the comparison circuit 5 is inverted until the output voltage S1 of the amplification circuit 3 is stabilized (in this embodiment, about 10 seconds after the power supply voltage is restored). (That is, the number of times the output voltage S1 of the amplifier circuit 3 exceeds the threshold voltage) is 4
It was found that the number of times was twice when the abnormality occurred in case 1, twice when the abnormality occurred in case 2, once or twice when the abnormality occurred in case 3, and five times when the abnormality occurred in case 4.
Although the number of times is six in the measurement results of FIGS. 12A and 12B, the number of times that the number of occurrences is assured as a result of the actual measurement is five.

Further, a fixed period after the output voltage S1 of the amplifier circuit 3 is stabilized (for example, about 10 seconds in this embodiment).
The number of times the output voltage S2 of the comparison circuit 5 is inverted (ie, the number of times the output voltage S1 of the amplification circuit 3 exceeds the threshold voltage)
As a result of the experiment, it was found that the number of times was 0 in the normal case, 8 in the case of abnormality in case 1, and 0 in the case of abnormality in cases 2, 3, and 4. In this embodiment, the output of the comparison circuit 5 generated immediately after the power supply voltage is restored is counted once, but the output at this time may be set not to be counted.

When the power supply voltage is momentarily stopped as described above, the output voltage S1 of the amplifier circuit 3 must be stable until the output voltage S1 becomes stable.
The number of times that the output voltage S2 of the comparator circuit 5 is inverted and the number of times that the output voltage S2 of the comparator circuit 5 are inverted during a certain period after the output voltage S1 of the amplifier circuit 3 is stabilized are normal and abnormal, respectively. The signal processing unit 10
Detects the abnormality of the PIR sensor A by detecting the number of times.

For example, when an abnormality of case 1 occurs,
After the output voltage S1 of the amplifier circuit 3 is stabilized, the comparison circuit 5
The number of times the output voltage S2 is inverted is greater than in the normal state, so that the occurrence of an abnormality in case 1 can be detected.

If an abnormality occurs in case 2 or 3,
Until the output voltage S1 of the amplifier circuit 3 is stabilized, the number of inversions of the output voltage S2 of the comparison circuit 5 is smaller than that in the normal state, so that the occurrence of abnormality in the case 2 or 3 can be detected. . This phenomenon occurs because the current path to the capacitor constituting the amplifier circuit 3 is cut off, the number of capacitors through which the charging current actually flows decreases, and the charging time as a whole becomes shorter.

When the abnormality of the case 4 occurs, the number of inversions of the output voltage S2 of the comparison circuit 5 before the output voltage S1 of the amplification circuit 3 becomes stable becomes larger than that in the normal state. Thus, the occurrence of an abnormality in case 4 can be determined. This phenomenon occurs when the gain of the amplifier circuit 3 increases and the output voltage S1 increases as compared with the normal state.

The output voltage of the comparison circuit 5 is maintained until the output voltage S1 of the amplifier circuit 3 is stabilized or for a certain period after the output voltage S1 is stabilized, depending on the time for instantaneously stopping the power supply voltage and the magnitude of the threshold voltage. Although the number of times S2 is inverted also changes, the time of the instantaneous stop and the magnitude of the threshold voltage may be set so that the number of times S2 does not become the same between the normal state and the abnormal state. Further, the number of times that the signal processing unit 10 determines whether or not the signal processing unit is normal may be changeable. By changing the number of times of determination, it is possible to cope with other abnormalities.
The time required for the output voltage S1 of the amplifier circuit 3 to stabilize can be calculated from the characteristics of the circuit and the like. However, an adjustment volume for changing this time is provided, and the time is set in accordance with the surrounding environment and use conditions. You may make it change.

By the way, in the abnormality detecting method according to the present invention, it is possible to specify which part of the above-mentioned parts has an abnormality, so that the signal processing unit 10 is provided with a determination function based on the number of pulses. , "Pyroelectric element error", "High-pass filter circuit error",
A warning message such as "feedback unit circuit abnormality" may be displayed.

For example, the resistor Rf2 of the amplifier circuit 3 shown in FIG.
Is open, or when the resistors R1 and R2 are both open in the circuit shown in FIG. 4, the output voltage S1 of the amplifier circuit 3 keeps oscillating to a lower side. Since the waveform does not change for a predetermined time, occurrence of an abnormality can be determined.
As shown in (a) and (b), when the power supply voltage is reduced to 0 V in the period T6, the output voltage S1 once swings to the high side when the power supply voltage returns, and continues to swing to the low side. If the waveform of S1 continues for a predetermined time or more after the momentary stop, it is possible to determine that the resistor Rf2 is abnormal by determining that the abnormality is abnormal.

Although the signal processing unit 10 performs the abnormality detection operation in the above-described manner, the signal processing unit 10 may cause the signal processing unit 10 to perform the abnormality detection operation at a desired timing. 10 may periodically perform an abnormality detection operation.

That is, a switch (not shown) for causing the signal processing unit 10 to perform an abnormality detection operation is provided, and an operator operates this switch to perform the abnormality detection operation at a desired timing. Alternatively, the signal processing unit 10 may be provided with a timer unit (not shown) that generates a trigger signal every predetermined time (for example, every 24 hours), and when the timer unit generates a trigger signal, the signal processing unit 10
The power supply voltage of the sensor A may be stopped for a predetermined time (about 5 seconds) to automatically perform the abnormality detection operation. When the abnormality detection operation is automatically performed, an adjustment volume for changing the time interval at which the trigger signal is generated may be provided in the timer unit so that the abnormality detection operation can be performed at a desired time interval. . In addition, when the abnormality detection operation is performed at a desired timing or periodically, the abnormality detection operation described above may be repeatedly performed a plurality of times at the time of one detection. As a result of the detection operation, if the abnormality of the PIR sensor A is detected twice or more, it may be determined that the abnormality has occurred, and the accuracy of the abnormality detection can be improved.

In addition, since the output voltage S1 of the amplifier circuit 3 exceeds the threshold voltage when a human body is detected, performing an abnormality detection operation in this state may erroneously detect that an abnormality of the case 1 has occurred. Therefore, when the signal processing unit 10 performs the abnormality detection operation, the pyroelectric element 2 detects infrared rays emitted from the human body, and the number of times that the output voltage S1 of the amplifier circuit 3 becomes equal to or higher than the threshold voltage is equal to or more than the predetermined number of times. (For example, in the case where the number of times that the output voltage S1 becomes equal to or higher than the threshold voltage is 5 or more in 10 seconds before the abnormality detection operation is performed), a certain period of time required for the output voltage S1 to stabilize (for example, about 30
Second), the timing of performing the abnormality detection operation may be shifted, so that it is possible to prevent erroneous detection of a human body detection as an abnormal state. In addition, the number of times (predetermined number) for judging that the human body is in the detection state, and the time for shifting the timing (constant time)
May be set to a predetermined value in advance, or may be changed by providing an adjustment volume.

In an alarm device that generates an alarm in response to a human body detection signal from the PIR sensor A, if a detection signal is continuously output from the PIR sensor A when a human body is detected, the alarm is continuously generated. Therefore, an off-delay period for ignoring the detection signal generated by the PIR sensor A is provided until a predetermined time elapses after the PIR sensor A once generates the detection signal of the human body, and a useless alarm signal is generated. Although the alarm is prevented from being continuously issued, the above-described abnormality detection operation may be performed during the off-delay period. In the PIR sensor A, the comparison circuit 5 compares the level of the output voltage S1 of the amplifier circuit 3 with a predetermined threshold voltage. When the output voltage S1 exceeds the threshold voltage, the human body detection signal is output. May be output, or
For example, the number of signals output from the comparison circuit 5 when a human body is detected is measured in advance, and the comparison circuit 5
It is also possible to determine whether or not the number of times of the signal output from is equal to the number of times when the human body is detected, and to output the human body detection signal only when this detection logic is established.

In the abnormality detection method according to the present invention, the power supply voltage of the PIR sensor A is instantaneously stopped to detect the abnormality. Therefore, there is a possibility that the human body may be unreported during this period. Since the human body detection signal generated by the sensor A may be ignored, the abnormality detection operation of the PIR sensor A is performed during this time, so that a false alarm generated by performing the abnormality detection operation can be eliminated. Note that the timing of performing the abnormality detection operation during the off-delay period may be set in advance to a convenient time such as the midpoint of the off-delay period, or about one second after the start of the off-delay period, The change may be made to any time during the off-delay period. If the abnormality detection operation is performed at a time other than during the off-delay period, a malfunction such as a false alarm may occur when the timing of the human body detection is exactly the same as the timing of the abnormality detection operation. Therefore, although there is a disadvantage that the abnormality detection operation cannot be performed without the human body detection, if the abnormality detection operation is performed only during the off-delay period, a malfunction such as a false alarm can be avoided.

[0042]

As described above, according to the first aspect of the present invention, there is provided the sensor according to the first aspect, wherein the sensor generates an electric signal having a magnitude corresponding to a variation in infrared energy radiated from a human body;
In the method of detecting an abnormality of a human body detector including an amplifying unit that amplifies an electric signal generated by a sensor unit, the power supply voltage is reduced for a predetermined time to a voltage equal to or lower than a predetermined voltage at which the voltage of each unit is sufficiently discharged, and then a constant is applied. In a state in which the output voltage of the amplifying unit is restored to a normal voltage, if the number of times the output voltage exceeds a predetermined threshold voltage is different from a normal time until the output voltage of the amplifier unit is stabilized, it is determined that the output voltage is abnormal. If the voltage is temporarily lowered and then restored, the number of times the output voltage exceeds the threshold voltage until the output voltage of the amplifier section becomes stable differs from the normal state. There is an effect that the state can be determined. In addition, the all-in-one type human body detector that has a comparison unit that compares the output voltage of the amplifying unit with the threshold voltage and detects only this output can detect the number of times the output of the comparison unit is inverted. Accordingly, it is possible to detect the number of times that the output voltage of the amplifier exceeds the threshold voltage, and to determine the abnormal state from the number of times.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, when the number of times is smaller than the normal time, it is determined that there is an abnormality. In the event of an abnormality such that the gain of the amplifier becomes smaller than normal, if the power supply voltage is temporarily lowered and then restored, the output voltage of the amplifier will become the threshold voltage until the output voltage becomes stable. Since the number of times exceeding the number of times is smaller than that in the normal state, there is an effect that the abnormal state can be determined by detecting the number of times.

According to a third aspect of the present invention, in the first aspect of the present invention, when the number of times is larger than the normal time, it is determined that the abnormality is abnormal. At the time of occurrence, if the power supply voltage is temporarily lowered and then restored, the number of times that the output voltage exceeds the threshold voltage until the output voltage of the amplifier section becomes stable will be larger than in the normal case. There is an effect that the abnormal state can be determined by the detection.

According to a fourth aspect of the present invention, there is provided a sensor unit for generating an electric signal having a magnitude corresponding to a change in infrared energy radiated from a human body, and an amplifying unit for amplifying the electric signal generated by the sensor unit. In the abnormality detection method of the human body detector, the power supply voltage is reduced to a predetermined voltage or less at which the voltage of each part is sufficiently discharged for a predetermined time, and then the output voltage of the amplification unit is restored to a voltage at a steady state. If the number of times the output voltage exceeds a predetermined threshold voltage during a certain period after the stabilization is different from the normal state, it is determined to be abnormal, and when the power supply voltage is temporarily lowered and then restored, Since the number of times that the output voltage exceeds the threshold voltage during a certain period after the output voltage of the amplifying section has stabilized is different from the normal state, detecting this number has the effect of determining an abnormal state. In addition, the all-in-one type human body detector that has a comparison unit that compares the output voltage of the amplifying unit with the threshold voltage and detects only this output can detect the number of times the output of the comparison unit is inverted. Accordingly, it is possible to detect the number of times that the output voltage of the amplifier exceeds the threshold voltage, and to determine the abnormal state from the number of times.

A fifth aspect of the present invention is characterized in that, in the fourth aspect of the present invention, when the number of times is larger than the normal time, it is determined that there is an abnormality. Since the output voltage of the amplifying unit is stabilized after the output voltage of the amplifier unit is stabilized, the number of times that the output voltage exceeds the threshold voltage is larger than that in the normal state. By detecting the number of times, the abnormality of the sensor unit is determined. There is an effect that can be.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the abnormality detecting operation is periodically performed, and the abnormality detecting operation is periodically performed to quickly detect the abnormality of the human body detector. There is an effect that can be detected.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, at the timing of performing the abnormality detecting operation, the sensor detects infrared rays radiated from the human body and determines that the output voltage of the amplifier is equal to or higher than the threshold voltage. If the number of times is equal to or more than a predetermined number of times, the output voltage of the amplifying unit exceeds the threshold voltage during the detection of a human body, characterized by shifting the timing of performing the abnormality detection operation for a certain period of time required for the output voltage to stabilize. If the abnormality detection operation is performed in this state, there is a possibility that the abnormal state may be erroneously detected. In this case, the timing of performing the abnormality detection operation is determined to be different from the time when the human body is detected, so that it is possible to prevent the detection of the human body from being erroneously detected as an abnormal state.

According to an eighth aspect of the present invention, in the first to fifth aspects of the present invention, the detection signal generated by the human body detector is generated for a predetermined time after the human body detector once generates the human body detection signal. Is characterized by providing an off-delay period in which the error is ignored, and performing an abnormality detection operation during this off-delay period. Since the power supply voltage is momentarily stopped to detect the abnormality, there is a possibility that the human body may be unreported during this period. However, during the off-delay period, the human body detection signal generated by the human body detector may be ignored.
There is no unreporting during the abnormality detection operation, and it is possible to prevent malfunction from occurring.

[Brief description of the drawings]

FIG. 1 is a block diagram of a PIR sensor to which an abnormality detection method for a human body detector according to the present invention is applied.

FIG. 2 is a specific circuit diagram of the PIR sensor.

FIG. 3 is a block diagram of an all-in-one PIR sensor to which the abnormality detection method is applied.

FIG. 4 is a specific circuit diagram of an amplifier circuit forming the PIR sensor according to the first embodiment.

5A and 5B are waveform diagrams of the above PIR sensor in a normal state, in which FIG. 5A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. 5B is a waveform diagram of an output voltage of a comparison circuit.

FIG. 6 is a waveform diagram when an abnormality of case 1 occurs in the PIR sensor according to the first embodiment, where (a) is an output voltage of an amplifier circuit,
(B) is a waveform diagram of the output voltage of the comparison circuit.

7A and 7B show waveform diagrams in the case where an abnormality of Case 4 occurs in the PIR sensor according to the first embodiment, and FIG.
(B) is a waveform diagram of the output voltage of the comparison circuit.

FIGS. 8A and 8B are waveform diagrams at the time of a detection operation when the PIR sensor is normally operating; FIG. 8A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. .

9A and 9B are waveform diagrams at the time of a detection operation when an abnormality of Case 1 occurs in the PIR sensor of the above, and FIG. 9A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. 9B is a waveform diagram of an output voltage of a comparison circuit. is there.

FIGS. 10A and 10B are waveform diagrams at the time of a detection operation when an abnormality of Case 2 occurs in the PIR sensor, in which FIG. 10A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. is there.

FIGS. 11A and 11B are waveform diagrams at the time of a detection operation when an abnormality of Case 3 occurs in the PIR sensor, in which FIG. 11A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. is there.

FIGS. 12A and 12B are waveform diagrams at the time of a detection operation when an abnormality of Case 4 occurs in the PIR sensor, in which FIG. 12A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. is there.

13A and 13B are waveform diagrams at the time of a detection operation when another abnormality occurs in the PIR sensor according to the first embodiment, in which FIG. 13A is a waveform diagram of an output voltage of an amplifier circuit, and FIG. 13B is a waveform diagram of an output voltage of a comparison circuit. .

[Explanation of symbols]

 A PIR sensor 2 pyroelectric element 3 amplifier circuit 4 bandpass filter 5 comparison circuit 10 signal processing unit S1 output voltage

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G08B 13/191 G01V 9/04 T (72) Inventor Hideki Kawahara 1048 Odakadoma, Kazuma, Osaka Prefecture Matsushita Electric Works, Ltd. F-term in the formula company (reference) 2G065 AB02 BA13 BC03 BC14 BC22 DA03 DA20 5C084 AA02 AA07 AA14 AA19 BB04 CC16 DD43 GG24 GG38 GG57 GG65

Claims (8)

[Claims] 1. A human body detector comprising: a sensor for generating an electric signal having a magnitude corresponding to a change in infrared energy emitted from a human body; and an amplifier for amplifying an electric signal generated by the sensor. In the abnormality detection method, the power supply voltage is reduced to a predetermined voltage or less at which the voltage of each part is sufficiently discharged for a predetermined time, and then restored to the steady state voltage until the output voltage of the amplifier becomes stable. If the number of times that the output voltage exceeds a predetermined threshold voltage during the period is different from the normal state, it is determined that an abnormality has occurred. 2. The method according to claim 1, wherein when the number of times is smaller than a normal number, it is determined that the number is abnormal. 3. The abnormality detecting method for a human body detector according to claim 1, wherein if the number of times is greater than normal, it is determined that the abnormality is abnormal. 4. A human body detector comprising: a sensor unit for generating an electric signal having a magnitude corresponding to a change amount of infrared energy radiated from a human body; and an amplifying unit for amplifying an electric signal generated by the sensor unit. In the abnormality detection method, after the power supply voltage is reduced to a predetermined voltage or less at which the voltage of each part is sufficiently discharged for a predetermined time, the power supply voltage is restored to a steady state voltage, and then the output voltage of the amplification section is stabilized. An abnormality detection method for a human body detector, wherein an abnormality is determined when the number of times the output voltage exceeds a predetermined threshold voltage during a certain period is different from a normal state. 5. The method for detecting an abnormality of a human body detector according to claim 4, wherein if the number of times is greater than normal, it is determined that the abnormality is abnormal. 6. The method for detecting an abnormality of a human body detector according to claim 1, wherein an abnormality detection operation is performed periodically. 7. The sensor unit detects infrared rays emitted from a human body at the timing of performing the abnormality detection operation. If the number of times that the output voltage of the amplifying unit exceeds the threshold voltage is equal to or more than a predetermined number, the output voltage is stabilized. 7. The method according to claim 1, wherein the timing of performing the abnormality detection operation is shifted for a certain period of time necessary for performing the operation. 8. An off-delay period for ignoring a detection signal generated by the human body detector is provided until a predetermined time elapses after the human body detector once generates a human body detection signal. 6. The abnormality detection method for a human body detector according to claim 1, wherein an abnormality detection operation is performed.