JPH0652451A - Heat ray type detector - Google Patents

Abstract

PURPOSE:To reduce misalarming output and improve the reliability. CONSTITUTION:The hot-wire detector is equipped with a sensor circuit 1 which outputs a 1st pulse having pulse width wider than a 1st specific time and a 2nd pulse within a 2nd specific time after the 1st pulse, a pulse counting timer circuit 2 which resets a 2nd state continuously for a 3rd specific time a little longer than the 2nd specific time unless a pulse is newly inputted in the 2nd state once the 1st pulse is inputted in a 1st state, a 1st gate circuit 3 which erases the pulse inputted in the 2nd state, a 2nd gate circuit 4 which erases the pulse inputted in the 1st state, and a pulse converting circuit 5 which converts the input pulses into pulses having pulse width shorter than the 1st specific time. The output of the sensor circuit 1 is inputted to the 1st gate circuit 3 and pulse converting circuit 5 and the output of the 1st gate is inputted to the pulse counting timer circuit 2; and the output of the pulse converting circuit 5 is inputted to the 2nd gate circuit 4 and the output of the 2nd gate circuit 4 is uses as an alarming output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat ray detector.

[0002]

2. Description of the Related Art FIGS. 4 to 6 are views showing a conventional hot-wire detector. FIG. 4 is a main circuit diagram showing the hot-wire detector. FIG. 5 is a timing chart showing the operation of each part of the heat ray detector, and as will be described later, FIG. 5 (a), ...
Indicate the voltage waveforms at the connection points P _a, ... P _h , respectively.
FIG. 6 is an explanatory diagram showing the operation of the sensor circuit 1 of the hot wire detector, and FIG. 6 (a) shows the output voltage waveform W of the amplifier 1 _b and the comparison reference level range L of the comparator 1 _c .
(B) shows the detection pulse output from the comparator 1 _c .

As shown in FIG. 4, the heat ray detector includes a sensor circuit 1 which outputs a detection pulse when an intruder is detected,
The retriggerable pulse count timer circuit 2 and the pulse count timer circuit 2 are in the second state when the detection pulse is input in the first state and return to the first state again when the detection pulse is not input for a predetermined time. A return signal circuit 3 that outputs a return trigger pulse when returning from the second state to the first state, and a pulse count timer circuit 2
Is in the second state, the pulse detection circuit 4 outputs a detection trigger pulse for each of the detection pulses; when the detection trigger pulse is input, the alarm output is started and when the return trigger pulse is input, the alarm output is output. And an alarm circuit 5 for stopping the alarm.

In the sensor circuit 1, the heat dose received changes.
And a pyroelectric element 1 that outputs a voltage according to the rate of change_aWhen,
Pyroelectric element 1_aAmplifier that amplifies the output voltage of the_bAnd the amplification
Bowl 1 _bDetection pulse when the output voltage exceeds the specified range
Comparator 1 that outputs_cIt consists of and. Servant
Then, when an intruder enters the warning area, the pyroelectric element 1_aReceiving
The heat dose to the amplifier 1_bFrom Fig. 6 (a)
A voltage waveform W as shown in is output. Then,
Lator 1_cIndicates that the part exceeding the comparison reference level range L is
A pulse output and a detection pulse as shown in FIG.
Output. The detection pulse when an intruder is detected
As shown in FIG. 6 (b), is a plurality of pulses within 5 seconds.
Is usually caused.

The pulse count timer circuit 2 comprises a timer circuit T, resistors R _{1 and} R ₂ , a diode D ₁ and a capacitor C ₁ . The timer circuit T is
When the timer circuit T is in the low output state, when the detection pulse is input from the sensor circuit 1, it becomes the high output state, and when the detection pulse is not input for a predetermined time, it returns to the low output state again, and is retriggerable. The pulse count timer circuit 2 is connected as follows. That is, the input of the timer circuit T is connected to the output of the sensor circuit 1, the output of the timer circuit T via the resistor R ₁ resistor R ₂
Of being connected to the cathode of the one end and the diode D _1, each of the anode and the other end a diode D ₁ of the resistor R ₂ is connected to one end of the capacitor C _1, the other end of the capacitor C ₁ is grounded.

The return signal circuit 3 is composed of resistors R _{3 and} R ₄ , capacitors C _{2 and} C ₃ , a diode D _2, and a NAND logic circuit 30. The return signal circuit 3 is connected as follows. That is, one end of the resistor R ₃ and one end of the capacitor C ₂ are connected to the cathode of the diode D ₁ of the pulse count timer circuit 2, respectively, and the resistor R 3
The other end of ₃ is connected to both inputs of the NAND logic circuit 30,
The output of the NAND logic circuit 30 is connected to the connection point between the resistor R ₄ and the anode of the diode D ₂ via the capacitor C ₃ , and the other end of the capacitor C _{2 and} the other end of the resistor R ₄ are both grounded. .

The pulse detection circuit 4 includes resistors R _5, R _6, R _7, R
₈ , a capacitor C _4, and a NAND logic circuit 40. The pulse detection circuit 4 is connected as follows. That is, one end of the resistor R ₅ is connected to the sensor circuit 1
Is the connection to the output, the other end of the resistor R ₅ is connected to the connection point between the resistor R ₆ through a capacitor C ₄ and a resistor R _7, the other of the resistor R ₇ is connected to one input of the NAND logic circuit 40 The other end of the resistor R ₆ is grounded. Also, NA
The other input of the ND logic circuit 40 is connected to the anode of the diode D ₁ of the pulse count timer circuit 2 via the resistor R ₈ .

The alarm circuit 5 has a resistor R_9,R_Ten,R₁₁, R₁₂
And capacitor C_FiveAnd NAND logic circuits 50 and 51
It consists of The alarm circuit 5 is connected as follows.
Has been. That is, one input of the NAND logic circuit 50
Force is resistance R₉Through the resistor R ₁₁End and return signal circuit 3
Diode D₂Connected to the cathode of the NAND theory
The other input of the logic circuit 50 is a resistor R_TenPulse detection via
Connected to the output of NAND logic circuit 40 of circuit 4
R₁₁The other end of is connected to the output of the NAND logic circuit 51,
Both inputs of the NAND logic circuit 51 are resistors R₁₂Connect to one end of
And the resistance R₁₂The other end of the capacitor C_FiveEnd and NAN
D is connected to the output of the logic circuit 50, and the capacitor C_Fiveof
The other end is grounded. And the NAND logic circuit 5
Issuing a hot-wire detector with an output of 0 configured as described above
It is output.

The hot-wire detector constructed as described above operates as follows. That is, the sensor circuit 1 is
If the detection pulse shown in (a) is output, Lo
The timer circuit T in the w output state becomes the High output state at the time point t ₁ as shown in FIG. 5B. Then, the potential at the connection point P _c changes from Low to High at a speed according to the time constant determined by the resistors R _{1 and} R ₂ and the capacitor C _1, and time t ₂
Then, the threshold value V _th of the NAND logic circuit 40 is reached, and the pulse count timer circuit 2 goes from the first state to the second state.
Further, as the voltage waveform at the connection point P _e , a differential waveform corresponding to the time constant determined by the resistors R _{5 and} R ₆ and the capacitor C ₄ appears, as shown in FIG. However, since the potential of the connection point P _e has already become Low at the time point t ₂ , NAN is set.
The output of the D logic circuit 40 (the potential of the connection point P _f ) remains High and does not show any change.

By the way, the sensor circuit 1 outputs the detection pulse again at the time point t ₃ . Then, as the voltage waveform at the connection point P _e , as shown in FIG. 5E, a differential waveform corresponding to the time constant determined by the resistors R _5, R ₆ and the capacitor C ₄ appears. Since the connection point P _c has already become High at the time point t ₃ , the output of the NAND logic circuit 40 shows that the potential at the connection point P _e becomes the threshold value V _th as shown in FIG. It becomes Low only when it is higher. Then, the NAND logic circuit 5
The output of 0 (potential at the connection point P _h ) becomes Low → High at time t ₃ , as shown in FIG. 5 (h). Then NAND
The output of the logic circuit 51 (potential at the connection point P _g ) is at time t ₃
High → Low. Then, this state continues until time t ₆ .

Time t₆At time t₁High output at
The timer circuit T which is in the state is again in the Low output state.
It This is because the timer circuit T is retriggered as described above.
When the timer circuit T is in the High output state
The final detection pulse input to the timer circuit T goes low.
After a predetermined time T₀Is no detection pulse input during
As a result, the low output state was restored again. Ie
In FIG. 5, time t _FiveFrom the predetermined time T₀Detected during
Since there was no pulse input, time t₆Low output again
It returned to the state. The predetermined time T₀Is
It is set to 3 minutes.

By the way, when the output of the timer circuit T changes from High to Low at the time point t ₆ , the positive charge charged in the capacitor C ₁ is rapidly discharged through the diode D ₁ , so that FIG. As shown in, the potential at the connection point P _c rapidly changes from High to Low and the pulse count timer circuit 2
Returns from the second state to the first state. Further, both inputs of the NAND logic circuit 30 become High → Low. Then NAN
The output of the D logic circuit 40 (potential of the connection point P _f ) remains High and does not show any change. However, the NAND logic circuit 30
Is changed from Low to High, a differential waveform in the High direction as shown in FIG. 5D is output as the voltage waveform at the connection point P _d . Then, the potential of the connection point P _g changes from Low to High.
And the output (connection point P _h ) of the NAND logic circuit 50 is
The output of the NAND logic circuit 51 changes from High to Low
Low → High, connection point P _g remains High and connection point P
_h comes to hold Low. That is, in the example of FIG. 5, the hot-wire detector produces a warning output in which the period from time t ₃ to time t ₆ is High.

Therefore, as is apparent from the above description,
At least the plurality of detection pulse is output from the sensor circuit 1 for a predetermined time T ₀ (3 minutes) following interval, alarm output to maintain at least a predetermined time T ₀ (3 minutes) or more periods High is, hot-wire It is output from the detector. It should be noted that the fact that a plurality of detection pulses are output and the alarm output is performed for the first time prevents the erroneous alarm that an alarm is output even if there is no intruder. , To improve reliability.

[0014]

However, in the above-mentioned heat ray type detector, the pulse count timer circuit 2 once in the second state is at least the predetermined time T.
The second state is maintained for the period of ₀ (3 minutes). Therefore, during the predetermined time T ₀ (3 minutes), the amplification noise level of the amplifier 1 _b becomes large for some reason, and the predetermined time T 0
_If it comes out of the comparison reference level range L of the comparator 1 _c within a cycle of ₀ (3 minutes), the alarm output is continued even if there is no intruder, and the false alarm status continues. To do. Even _if the amplification noise level of the amplifier 1 _b does not deviate from the comparison reference level range L of the comparator 1 _{c in} a cycle within a predetermined time T ₀ (3 minutes), the predetermined time T ₀ is as long as 3 minutes. However, there is a problem that the risk of false alarm due to sudden noise of the amplifier 1 _b increases.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly reliable hot-wire detector with few false alarms.

[0016]

In order to solve the above-mentioned problems, the present invention, when detecting an intruder, uses a first pulse having a pulse width of a first predetermined time or more as a detection pulse and a second predetermined pulse from the first pulse. A sensor circuit that outputs at least a second pulse during the lapse of time, and a pulse having a pulse width of the first predetermined time or more in the first state enters the second state and enters a new pulse unless a new pulse is input. A pulse count timer circuit that continues the second state for a third predetermined time slightly longer than the second predetermined time and returns to the first state again, and erases a pulse that is input when the pulse count timer circuit is in the second state. A first gate circuit, a second gate circuit that erases a pulse that is input when the pulse count timer circuit is in the first state, and an input pulse that has a pulse width of less than the first predetermined time. A pulse conversion circuit for converting the output of the sensor circuit to the first gate circuit and the pulse conversion circuit, and an output of the first gate circuit to the pulse count timer circuit, The output of the pulse conversion circuit is input to the second gate circuit,
It is characterized in that the output of the gate circuit is used as an alarm output.

[0017]

With the above configuration, when an intruder is present and the first pulse having the pulse width of the first predetermined time or longer starts to be output from the sensor circuit, the first gate circuit outputs the pulse to the pulse count timer circuit. Start printing. Then, when the first predetermined time elapses, the pulse count timer circuit becomes the first
The state changes from the second state. When the pulse count timer circuit is in the second state, the first gate circuit is configured to erase the pulse from the sensor circuit, and when the pulse count timer circuit is in the second state, the pulse count timer circuit is in the second state unless a new pulse is input. The state is maintained for a third predetermined time which is slightly longer than the second predetermined time. Therefore, the pulse count timer circuit continues the second state for the third predetermined time and then returns to the first state again. By the way, the pulse conversion circuit converts the first pulse from the sensor circuit into a pulse having a pulse width shorter than the first predetermined time and outputs the pulse to the second gate circuit. However, the pulse count timer circuit is in the first state during the period in which the pulse converted from the first pulse into the pulse having the pulse width shorter than the first predetermined time is input to the second gate circuit, and the second gate circuit is in the first state. The circuit is adapted to cancel incoming pulses. Therefore, the pulse output corresponding to the first pulse from the pulse conversion circuit is not output from the second gate circuit.

However, at least the second pulse is output from the sensor circuit during the second predetermined time after the first pulse is output from the sensor circuit and the pulse count timer circuit is in the second state. Then, the pulse conversion circuit converts the second pulse into a pulse having a pulse width of less than the first predetermined time and outputs the pulse to the second gate circuit, and the pulse output corresponding to the second pulse from the pulse conversion circuit is the second pulse. It is output from the gate circuit. That is, the hot-wire detector does not issue a warning output with the first pulse from the sensor circuit, but outputs a warning with the second pulse.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A heat ray type detector according to an embodiment of the present invention will be described below in detail with reference to FIGS. 1 and 2 and another embodiment with reference to FIG. FIG. 1 is a circuit diagram of a main part of a hot wire detector. FIG. 2 is a timing chart showing the operation of each part of the hot-wire detector, and FIG. 2 (a), ..., FIG. 2 (g).
Indicate the voltage waveforms at the connection points P _a, ... P _g , respectively.
FIG. 3 is a circuit diagram of a main part of the hot wire detector.

As shown in FIG. 1, the hot wire type detector is
When a person is detected, the detection pulse is a first predetermined time T₁that's all
Pulse of the pulse width of and the second predetermined time from the first pulse
Interval T ₂Outputs at least a second pulse during the passage
The sensor circuit 1 and the first predetermined time T when in the first state₁
When a pulse with the above pulse width is input, it enters the second state.
Unless a new pulse is input, the second state is changed to the second place.
Fixed time T₂A slightly longer third predetermined time T₃Continue to re
And a pulse count timer circuit 2 for returning to the first state,
Input when the pulse count timer circuit 2 is in the second state
The first gate circuit for erasing the pulse
The pulse to be input when the untimer circuit 2 is in the first state
The second gate circuit for erasing and the input pulse for the first
Predetermined time T₁Pulse to convert to pulse with pulse width less than
And a conversion circuit 5.

The sensor circuit 1 is the same as that described in the conventional example, and when the received heat dose changes, the pyroelectric element 1 _a that outputs a voltage according to the rate of change and the output of the pyroelectric element 1 _a . It is composed of an amplifier 1 _b that amplifies the voltage and a comparator 1 _c that outputs a detection pulse when the output voltage of the amplifier 1 _b exceeds a predetermined range. When the intruder enters the caution area, the heat dose received by the pyroelectric element 1 _a changes, so that the amplifier 1 _b outputs a voltage waveform obtained by amplifying the voltage waveform output by the pyroelectric element 1 _a . Then, the comparator 1 _c outputs a detection pulse by making a portion exceeding the comparison reference level range into a pulse output. In the sensor circuit 1 shown in FIG. 1, a detection pulse when an intruder is detected usually produces a plurality of pulses within the second predetermined time T ₂ (5 seconds). The pulse width of the first pulse (first pulse) of the plurality of pulses is usually the pulse width of the first predetermined time T ₁ or more. Further, in the sensor circuit 1 shown in FIG. 1, the Low output is the pulse output.

The pulse count timer circuit 2 includes NOR logic circuits 20, 21 and resistors R _1, R _2, R _3, R _4, R _5, R _6, R.
_7, R ₈ , capacitors C _{1 and} C ₂ , diode D ₁ ,
It is composed of transistors T _{r1 and} T _r2 . The first gate circuit is composed of the NOR logic circuit 3, and the second gate circuit is composed of the NOR logic circuit 4. The pulse conversion circuit 5 is composed of resistors R _{9 and} R ₁₀ , a capacitor C _3, and a diode D ₂ .

The respective configurations as described above are connected as follows. That is, the output of the sensor circuit 1 (connection point P _a ) is connected to one input of the NOR logic circuit 3 and one end of the capacitor C ₃ of the pulse conversion circuit 5, and the other end of the capacitor C ₃ is connected to the resistor R ₉ . It is connected to one end, one end of the resistor R ₁₀ and the anode of the diode D ₂ . Resistance R
The other end of ₉ and the cathode of the diode D ₂ are respectively connected to the power supply V _DD, and the other end of the resistor R ₁₀ is connected to one input (connection point P _b ) of the NOR logic circuit 4.

The output of the NOR logic circuit 3 (connection point P _c ) is connected to one end of the resistor R ₁ of the pulse count timer circuit 2, and the other end of the resistor R ₁ is connected to _one end of the resistor R ₂ and the transistor T 1.
It is connected to the base of _r1 and the other end of the resistor R ₂ and the emitter of the transistor T _r1 are grounded. The collector of the transistor T _r1 is connected to one end of the resistor R ₃ ,
The other end of the resistor R ₃ is connected to one end of the one end and the capacitor C ₁ of the resistor R _4, the other end of the resistor R ₄ is connected to the base of one end and the transistor T _r2 of the resistor R _5, the capacitor C ₁
The other end of the emitter of the other end transistor T _r2 of the resistor R ₅ is respectively connected to the power supply V _DD, the collector of the transistor T _r2 is connected to one end of the resistor R _6, the other end of the resistor R ₆ (connecting point P _e ) is connected to one end of the resistor R ₇ , one end of the resistor R ₈ , one end of the capacitor C ₂ and the cathode of the diode D ₁ , respectively, and the other end of the resistor R ₇ and the anode of the diode D ₁ are grounded, The other end of the capacitor C ₂ has a power source V
_It is connected to _DD and the other end of the resistor R ₈ is connected to one input of the NOR logic circuit 21. The other input of the NOR logic circuit 21 is connected to the output of the NOR logic circuit 4 (connecting point P _g), the output of the NOR logic circuit 21 (the connection point P _f) is N
It is connected to the other input of the OR logic circuit 4 and both inputs of the NOR logic circuit 20, and the output of the NOR logic circuit 20 is NOR.
It is connected to the other input of the logic circuit 3. And N
The output of the OR logic circuit 4 (connection point P _g ) is used as the alarm output of this heat ray detector.

The heat ray type detector constructed as described above is as follows.
Works like. That is, the sensor circuit 1 is
As shown in (a), time t₁Then, the first predetermined time T₁that's all
If a pulse having a pulse width of₁To
Indexer C₃And resistance R₉Depending on the time constant determined by
As shown in FIG. 2 (b), the split waveform shows the connection point P_bOutput to
Connection point P_bIs at time t₁From time t₂Period of Lo
becomes w. Also, at time t ₁Output of NOR logic circuit 3
(Connection point P_c) Becomes Low → High. Then Tran
Dista T_r1Is turned on and the connection point P_dPotential is High → Low
And the transistor T_r2Starts to turn on and connection point P_eIs
Starts to go from Low to High. The capacitor C₂Capacity
Is large, so connection point P_eChange in potential slowly
Yes, time t ₃Finally connection point P_ePotential is a threshold
V_thAnd reaches High, and the pulse count timer circuit 2
Changes from the first state to the second state.

When the pulse count timer circuit 2 enters the second state at time t ₃ , the output of the NOR logic circuit 21 (connection point P _f ) changes from High to Low, and the output of the NOR logic circuit 20 changes from Low to High. Then, the output of the NOR logic circuit 3 (connection point P _c ) becomes Low. Then, the transistor T _r1 is turned off, the transistor T _r2 is also turned off, and the connection point P
The electric potential of _e reaches the maximum electric potential some time after the time point t ₃ and then starts decreasing, and becomes lower than the threshold value V _th at the time point t ₄ and becomes Low. In other words, the pulse count timer circuit 2 is made the first state → second state when t _3, after the second state the third predetermined time T ₃ continues, at time t ₄ again to the second state → the first state Return.

By the way, although the potential at the connection point P _b is Low during the period from the time point t ₁ to the time point t ₂ , the pulse count timer circuit 2 is in the first state during the period from the time point t ₁ to the time point t _3. Therefore, the output (connection point P _g ) of the NOR logic circuit 4 remains low without any change.

As is apparent from the above description, the time point t.₁
The pulse width from the sensor circuit 1 that starts to be output at
Fixed time T₁(Time t₁From time t₃Up to)
If so, the pulse count timer circuit 2 goes from the first state to the second state.
The output of NOR logic circuit 4 cannot be established
(Connection point P_g) Remains low without any change
Therefore, the heat ray type detector does not issue a warning output. Also, at time t
₁Pulse from the sensor circuit 1 which starts to be output at
The width is the first predetermined time T₁Above, the pulse counter
Even if the imager circuit 2 changes from the first state to the second state,
Point t₃From time t _FourDuring the period of
The output of NOR logic circuit 4 (connection
Point P_g) Remains low without any change,
The type detector does not issue a warning output.

Now, suppose that the heat ray detector detects an intruder at time t ₅ , the sensor circuit 1 outputs a detection pulse as
As shown in FIG. 2A, a first pulse having a pulse width of a first predetermined time T ₁ or more is output at time t ₅ , and a second predetermined time T ₂ (5 seconds) elapses from the first pulse. Between time points t
_{At 8} , at least the second pulse is output.

Then, time t_FiveFrom time t₇Until
Connection point P_b,… P_gEach operation of the₁Since
Point t₃Up to the connection point P
_c,P _d,P_e,P_fAt that time t₃From time t_TenFor up to
The time period is also t₃From time t_FourSame as up to
To operate. That is, the above-mentioned time t₁From time t_FourWell
The difference from the operation during the period at₈To the capacitor
C₃And resistance R₉Differential waveform according to the time constant determined by
However, as shown in FIG._bIs output to
Continuation point P_bIs at time t₈From time t₉Is low during
Is Rukoto.

By the way, at this time t₈From time t₉Period of
While the pulse count timer circuit 2 is in the second state,
Since it is also during the period, the output of the NOR logic circuit 4 (connection
Point P _g) Is at time t₈Low → High at time t₉At Hi
gh → Low, time t₈From time t₉Is high for
A pulse is output. In other words, the heat ray type detector
Point t₈From time t₉During this period, a warning is output.

As is apparent from the above description, in the above-mentioned heat ray type detector, the sensor circuit 1 outputs the first pulse having the pulse width of the first predetermined time T ₁ or more, and the first pulse
If at least the second pulse is output until the second predetermined time T ₂ (5 seconds) elapses from the pulse, the alarm output corresponding to the first pulse is not generated, but the pulse conversion is performed corresponding to at least the second pulse. The alarm output of the pulse width of the pulse output from the circuit 5 is output from the heat ray detector. Therefore, even in the above-mentioned heat ray type detector, a plurality of pulses are output from the sensor circuit 1 and the alarm output is made for the first time, which is the same as the conventional one, even though there is no intruder. In the same manner, the false alarm that the notification is output without being issued is prevented. In addition, the retriggerable operation of the pulse count timer circuit 2 is blocked by the first gate circuit (NOR logic circuit 3), and further, the third predetermined time T ₃ is the second predetermined time T ₃ in consideration of the characteristics of the sensor circuit 1. The time is set to be slightly longer than the predetermined time T ₂ (5 seconds). Therefore, it is more difficult to give a false alarm to the noise of the amplifier 1 _b than the conventional one, and the reliability is improved.

Next, another embodiment will be described with reference to FIG.
It The hot-wire detector shown in FIG. 3 is the hot-wire detector shown in FIG.
This is the reverse of the logic of the circuit of the vessel. That is,
Power supply V _DDIs used as a cathode power source and the detection circuit from the sensor circuit 1
The pulse output is high pulse output, and the alarm output is low pulse output.
Energized transistor T_r1,T_r2Is an NPN type
Diode D_1,D₂Direction is reversed and NOR logic
Circuits 3, 4, 20, 21 are NAND logic circuits
It

The operation of the hot-wire type detector shown in FIG. 3 is such that the relationship between High and Low in the timing chart shown in FIG. 2 is reversed. Therefore, although the timing diagram of the hot-wire detector shown in FIG. 3 and the operation description thereof are omitted, the alarm output is generated only after a plurality of pulses are output from the sensor circuit 1, and the first gate circuit (NAND The retriggerable operation of the pulse count timer circuit 2 is blocked by the logic circuit 3), and the third predetermined time T ₃ is slightly shorter than the second predetermined time T ₂ (5 seconds) in consideration of the characteristics of the sensor circuit 1. It is similar to the hot-wire type detector of FIG. 1 in that it is set to a long time.

The present invention is not limited to the above embodiment, but includes other logic circuits and elements such as a pulse count timer circuit, a first gate circuit, a second gate circuit,
It goes without saying that a pulse conversion circuit may be configured.

[0036]

Since the heat ray detector according to the present invention is constructed as described above, even if the noise level of the sensor circuit becomes high for some reason, the false alarm output is continuously output. The third predetermined time is set to a time slightly longer than the second predetermined time, and it is not set to a long time such as 3 minutes unlike the conventional one. Therefore, even if noise with a long pause interval is output from the sensor circuit, the probability that a false alarm is output is small, and a hot wire detector with improved reliability can be provided.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of a hot-wire detector according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the hot-wire detector of one embodiment according to the present invention.

FIG. 3 is a main part circuit diagram showing a hot-wire detector of another embodiment according to the present invention.

FIG. 4 is a main part circuit diagram showing a conventional hot-wire detector.

FIG. 5 is a timing chart showing the operation of the conventional hot wire detector.

FIG. 6 is an explanatory diagram showing the operation of the sensor circuit of the hot-wire detector.

[Explanation of symbols]

1 sensor circuit 2 pulse count timer circuit 3 first gate circuit 4 second gate circuit 5 pulse conversion circuit T ₁ first predetermined time T ₃ third predetermined time

Claims (1)

[Claims] 1. A sensor circuit which, when detecting an intruder, outputs a first pulse having a pulse width of a first predetermined time or more as a detection pulse and at least a second pulse during a second predetermined time from the first pulse. When a pulse having a pulse width of the first predetermined time or more is input in the first state, the second state is established and the second state is set to a third predetermined length slightly longer than the second predetermined time unless a new pulse is input. A pulse count timer circuit that continuously returns to the first state for a time, a first gate circuit that erases a pulse input when the pulse count timer circuit is in the second state, and the pulse count timer circuit is in the first state. The sensor circuit includes a second gate circuit that erases a pulse that is input at this time, and a pulse conversion circuit that converts the input pulse into a pulse having a pulse width of less than the first predetermined time. Is input to the first gate circuit and the pulse conversion circuit, the output of the first gate circuit is input to the pulse count timer circuit, and the output of the pulse conversion circuit is input to the second gate circuit. , The second
A heat ray detector characterized in that the output of a gate circuit is used as a warning output.