JP3458735B2 - Infrared detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detecting device for detecting infrared energy radiated from a human body to detect the presence or movement of the human body.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of a conventional infrared detecting device of this type. The pyroelectric element 1 is widely used as an infrared detection unit, and infrared rays from the detection area are collected in the pyroelectric element 1 by using a lens system or the like, and the amount of infrared rays collected from the pyroelectric element 1 is detected. A current corresponding to the change is output. The current output from the pyroelectric element 1 is converted into a voltage by the I / V conversion circuit 2 and then further amplified by the first voltage amplification circuit 3a.

The frequency characteristic of the infrared detecting device is set in accordance with the movement of the human body, and a bandpass filter centering at approximately 1 Hz is added to the first voltage amplifying circuit 3a. This makes it possible to increase the sensitivity to the human body and prevent a malfunction due to a signal in a band that is considered to be unrelated to the movement of the human body.

However, the pyroelectric element 1 may generate a solitary noise output called popcorn noise. The second voltage amplification unit 3b selects a signal having a higher frequency than the first voltage amplification unit 3a and amplifies the output of the IV conversion circuit 2. Pyroelectric element 1 due to popcorn noise
Since the output from the device rises much faster than the output from the movement of the human body, the second voltage amplifier circuit 3
b has the characteristic of a high band pass filter that passes a component of several tens Hz or higher. This makes it possible to distinguish between popcorn noise and the output due to movement of the human body. The popcorn noise detection unit 5 controls the control circuit 6 when the second voltage amplification unit 3b has an amplitude equal to or larger than a predetermined value.
A popcorn noise detection signal is output to. The control circuit 6 receives the popcorn noise detection signal,
By lowering the conversion impedance of the IV conversion circuit 2 or lowering the gain of the first voltage amplification section 3a over a predetermined time, it is possible to prevent malfunction due to popcorn noise.

[0005]

However, in the analog output type infrared detector, the output fluctuation due to the popcorn noise can be reduced, but it is difficult to completely eliminate it, and as described above, the popcorn noise is generated. Immediately after that, there occurs a period in which the device does not respond for a predetermined time, but there is a problem that it is not possible to cope with this inactive period because the state cannot be judged from the output.

The present invention has been made to solve the above problems, and an object of the present invention is to apply a bias voltage to an amplifier or the like constituting an IV conversion circuit or a voltage amplification section in an infrared detection section. Even if there is, or even if popcorn noise occurs until the signal stabilizes, it eliminates the so-called false alarm that outputs the alarm signal as the detection target is detected, and these factors make detection sensitivity unnecessary. It is an object of the present invention to provide an excellent infrared detection device that prevents so-called false alarms in which the presence or movement of the original human body cannot be detected due to a decrease in the temperature for a long period of time.

[0007]

According to a first aspect of the present invention, there is provided a pyroelectric element, an I / V conversion circuit for converting a current signal output from the pyroelectric element into a voltage signal, and the I / V conversion circuit. A first voltage amplifying section for amplifying an output, a second voltage amplifying section for passing a signal having a frequency higher than that of the first voltage amplifying section, and amplifying an output of the I / V conversion circuit; When the output of the voltage amplification unit exceeds a predetermined value, a popcorn noise detection unit that determines that popcorn noise has occurred and outputs a popcorn noise detection signal, and the popcorn noise detection signal is output. A control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit, and the first circuit between the first voltage amplification unit and the analog output terminal by the output from the control circuit. Voltage amplifier Have the output switching section for switching the signals other than the output of the analog output is the detection signal, the
If the popcorn noise detection signal is output,
The analog output that is the detection signal from the voltage amplification unit 1
Output is switched off to switch to the reference potential used inside the road.
It is an infrared detection device characterized in that a replacement part works .

[0008]

The invention according to claim 2 is a pyroelectric element and a pyroelectric element.
I / V converter that converts the output current signal into a voltage signal
Conversion circuit and a first power amplifier for amplifying the output of the I / V conversion circuit.
The voltage amplification unit and the signal of a higher frequency than the first voltage amplification unit.
Second signal for amplifying the output of the I / V conversion circuit
And the output of the second voltage amplifying unit is predetermined.
Popcorn noise is generated when the specified value is exceeded.
Output popcorn noise detection signal
Popcorn noise detector and the popcorn noise
When the detection signal is output, the detection from the first voltage amplification unit is performed.
Control circuit that performs signal control for analog output that is a known signal
And the first voltage amplification by the output from the control circuit
The first voltage amplifying section between the section and the analog output terminal.
The analog output that is the detection signal from
When the popcorn noise detection signal is output, the output switching unit switches the analog output, which is the detection signal from the first voltage amplification unit, to the GND signal of the circuit. Red characterized by working
It is an outside line detection device .

The invention according to claim 3 is a pyroelectric element and a pyroelectric element.
I / V converter that converts the output current signal into a voltage signal
Conversion circuit and a first power amplifier for amplifying the output of the I / V conversion circuit.
The voltage amplification unit and the signal of a higher frequency than the first voltage amplification unit.
Second signal for amplifying the output of the I / V conversion circuit
And the output of the second voltage amplifying unit is predetermined.
Popcorn noise is generated when the specified value is exceeded.
Output popcorn noise detection signal
Popcorn noise detector and the popcorn noise
When the detection signal is output, the detection from the first voltage amplification unit is performed.
Control circuit that performs signal control for analog output that is a known signal
And the first voltage amplification by the output from the control circuit
The first voltage amplifying section between the section and the analog output terminal.
The analog output that is the detection signal from
And an output switching unit for switching, and when the popcorn noise detection signal is output, the output switching unit works so as to switch the analog output which is the detection signal from the first voltage amplification unit to the external power supply. Infrared detection featuring
It is a device .

The invention of claim 4 is a pyroelectric element and a pyroelectric element.
I / V converter that converts the output current signal into a voltage signal
Conversion circuit and a first power amplifier for amplifying the output of the I / V conversion circuit.
The voltage amplification unit and the signal of a higher frequency than the first voltage amplification unit.
Second signal for amplifying the output of the I / V conversion circuit
And the output of the second voltage amplifying unit is predetermined.
Popcorn noise is generated when the specified value is exceeded.
Output popcorn noise detection signal
Popcorn noise detector and the popcorn noise
When the detection signal is output, the detection from the first voltage amplification unit is performed.
Control circuit that performs signal control for analog output that is a known signal
And the first voltage amplification by the output from the control circuit
The first voltage amplifying section between the section and the analog output terminal.
The analog output that is the detection signal from
An output switching unit for switching, and when a popcorn noise detection signal is output, the analog output which is the detection signal from the first voltage amplification unit is switched to the output of the oscillation circuit used inside the circuit. The infrared detecting device is characterized in that the output switching section operates.

The invention of claim 5 is a pyroelectric element and a pyroelectric element.
I / V converter that converts the output current signal into a voltage signal
Conversion circuit and a first power amplifier for amplifying the output of the I / V conversion circuit.
The voltage amplification unit and the signal of a higher frequency than the first voltage amplification unit.
Second signal for amplifying the output of the I / V conversion circuit
And the output of the second voltage amplifying unit is predetermined.
Popcorn noise is generated when the specified value is exceeded.
Output popcorn noise detection signal
Popcorn noise detector and the popcorn noise
When the detection signal is output, the detection from the first voltage amplification unit is performed.
Control circuit that performs signal control for analog output that is a known signal
And the first voltage amplification by the output from the control circuit
The first voltage amplifying section between the section and the analog output terminal.
The analog output that is the detection signal from
And an output switching unit for switching, and when the popcorn noise detection signal is output, the output switching unit switches the analog output which is the detection signal from the first voltage amplification unit to an open state. Characterized by working
It is an infrared detector .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an infrared detection device according to the present invention is shown in FIGS. 1 and 2, a second embodiment is shown in FIG. 3, and a third embodiment is shown in FIG. 4, the fourth embodiment is shown in FIG. 5, and the fifth embodiment is shown in FIG.
Each will be described in detail.

[First Embodiment] FIG. 1 is a block diagram of an infrared detector. FIG. 2 is a timing chart explaining the operation of the infrared detection device. The infrared detection device includes a pyroelectric element 1, an IV conversion circuit 2, a first voltage amplification unit 3a, a second voltage amplification unit 3b, an output switching unit 4, a popcorn noise detection unit 5, and a control circuit 6. .

The pyroelectric element 1 outputs a current according to a change in the amount of infrared rays radiated from the detection area. The I / V conversion circuit 2 converts the detection current output from the pyroelectric element 1 into a voltage. The voltage converted signal is branched,
One is input to the first voltage amplifier 3a and the other is input to the second voltage amplifier 3b. The first voltage amplification unit 3 a amplifies the signal input from the I / V conversion circuit 2 and inputs the amplified signal to the output switching unit 4. The second voltage amplification unit 3b selects a frequency higher than that of the first voltage amplification unit 3a and amplifies the output of the I / V conversion circuit 2.

Since the output from the pyroelectric element 1 due to popcorn noise rises much faster than the output due to the movement of the human body or the like, the second voltage amplifier circuit 3b.
Has a characteristic of a high band pass filter that passes a component of several tens Hz or more. This makes it possible to distinguish between popcorn noise and the output due to movement of the human body. The popcorn noise detection unit 5 outputs a popcorn noise detection signal to the control circuit 6 when the second voltage amplification unit 3b has an amplitude equal to or larger than a predetermined value. When the popcorn noise detection signal is input, the control circuit 6 outputs the output control signal to the output switching unit 4 for a predetermined time. The output switching unit 4 outputs another predetermined signal to the analog output while the output control signal is input from the control circuit 6, instead of passing the output from the first voltage amplification unit 3a as it is. To switch.

FIG. 2 is a timing chart showing the operation of the infrared detecting device. FIG. 2A is an output waveform of the I / V conversion circuit 2. The first fluctuation (1) shows a signal when a human body is detected, and the next fluctuation (2) shows that due to popcorn noise. ing. FIG. 2B shows the waveform of the output of the control circuit 6. 2C shows an analog output waveform, and while the control circuit 6 outputs the control signal, the output is VRE which is the internal reference voltage of the circuit.
It is when it was switched to F. Generally, since the output from the pyroelectric element 1 is weak, the I / V conversion circuit 2 and the first
The amplification factor of the signal in the voltage amplifying section 3a is considerably high. Therefore, the output noise in the analog output while the signal is not input, that is, in the steady state cannot be ignored. On the other hand, when the internal reference voltage VREF of the circuit is directly output, the steady noise on this signal is negligible as compared with the output noise in the steady state described above. Therefore, if the output is monitored with higher accuracy than the amplitude of the output noise in this steady state,
It becomes possible to identify that the analog output has switched to VREF. That is, it is possible to confirm the occurrence of popcorn noise.

[Second Embodiment] As shown in FIG. 1, the second embodiment has a pyroelectric element 1, an IV conversion circuit 2, a first voltage amplifying section 3a, a second voltage amplifying section 3b, and an output switch. It is composed of a unit 4, a popcorn noise detection unit 5, and a control circuit 6 (not shown). When popcorn noise occurs, the waveform of the analog output is GN output by the output switching unit 4 while the control circuit 6 is outputting the control signal as shown in FIG. 3C.
It is switched to the D potential. The basic configuration of the infrared detection device of the present embodiment is very similar to that of the first embodiment as described above, and the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

[Third Embodiment] The basic configuration is, as shown in FIG. 1, a pyroelectric element 1, an IV conversion circuit 2, a first voltage amplification section 3a, a second voltage amplification section 3b, and output switching. It is composed of a unit 4, a popcorn noise detection unit 5, and a control circuit 6 (not shown). When popcorn noise occurs, the waveform of the analog output is switched to the VDD potential, which is the external power supply voltage, by the output switching unit 4 while the control circuit 6 outputs the control signal as shown in FIG. 4C. The basic configuration of the infrared detector of the present embodiment is very similar to that of the first embodiment, and the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

[Fourth Embodiment] The basic configuration is as shown in FIG. 1, in which the pyroelectric element 1, the IV conversion circuit 2, the first voltage amplifying section 3a, the second voltage amplifying section 3b, and the output switching. It is composed of a unit 4, a popcorn noise detection unit 5, a control circuit 6, and an oscillation circuit 7 (not shown). When popcorn noise occurs, the waveform of the analog output is switched to the output of the oscillation circuit 7 by the output switching unit 4 while the control circuit 6 is outputting the control signal as shown in FIG. 5C. The basic configuration of the infrared detector of the present embodiment is very similar to that of the first embodiment, and the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

[Fifth Embodiment] As shown in FIG. 1, the fifth embodiment has a pyroelectric element 1, an IV conversion circuit 2, a first voltage amplifying section 3a, a second voltage amplifying section 3b, and an output switch. It is composed of a unit 4, a popcorn noise detection unit 5, and a control circuit 6 (not shown). When popcorn noise occurs, the waveform of the analog output is switched to the output in the open state by the output switching unit 4 while the control circuit 6 is outputting the control signal as shown in FIG. 6C. The basic configuration of the infrared detector of the present embodiment is very similar to that of the first embodiment, and the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

[0022]

As described above, according to the invention of claim 1, when the popcorn noise occurs, the output is switched by the output switching unit. Therefore, it is determined that the detection target is detected by the popcorn noise and the alarm signal is output. It is possible to eliminate the so-called false alarm that may occur and to provide an excellent infrared detection device that can identify the occurrence of popcorn noise from the output signal. And further,
When the circuit of the present invention is integrated into an IC, it is simulated when the IC is inspected.
By inputting a signal like popcorn noise into
From the analog output terminal to the internal reference voltage VREF
Can be monitored.
The effect that the IC can be downsized without the need to provide a pad
Play.

[0023]

According to the invention of claim 2 , popcorn
When noise occurs, the output switching unit switches the output.
Therefore, if the detection target is detected by popcorn noise,
Then, to eliminate the so-called false alarm that outputs the alarm signal
Also, is it an output signal that popcorn noise has occurred?
To provide an excellent infrared detector that can be identified from
Produce an effect. Then, further, GND is the most stable potential, because there everywhere circuit, an effect that can be achieved in a small-scale circuit.

According to the invention of claim 3 , popcorn
When noise occurs, the output switching unit switches the output.
Therefore, if the detection target is detected by popcorn noise,
Then, to eliminate the so-called false alarm that outputs the alarm signal
Also, is it an output signal that popcorn noise has occurred?
To provide an excellent infrared detector that can be identified from
Produce an effect. Then, further, usually analog output is impossible is to become VCC potential higher than the internal power supply voltage, since the switch which in a an external power supply voltage VDD (> VCC), more accurate high stable operation realized It has the effect of being able to.

According to the invention of claim 4 , popcorn
When noise occurs, the output switching unit switches the output.
Therefore, if the detection target is detected by popcorn noise,
Then, to eliminate the so-called false alarm that outputs the alarm signal
Also, is it an output signal that popcorn noise has occurred?
To provide an excellent infrared detector that can be identified from
Produce an effect. Then, further, by providing the oscillation circuit dedicated since usually becomes the output that is not outputted by mistake in, together with a more accurate high operation can be realized, utilizing the oscillation signal in the circuit after the analog output There is an effect that it becomes possible.

According to the invention of claim 5 , popcorn
When noise occurs, the output switching unit switches the output.
Therefore, if the detection target is detected by popcorn noise,
Then, to eliminate the so-called false alarm that outputs the alarm signal
Also, is it an output signal that popcorn noise has occurred?
To provide an excellent infrared detector that can be identified from
Produce an effect. Then, further, is switched to a state for example, a high-impedance open the output, the user side is an effect that the output terminals can be arbitrarily set, such as pull-up or pull-down.

[Brief description of drawings]

FIG. 1 is a block diagram showing an infrared detection device according to a first embodiment of the present invention.

FIG. 2 is a timing chart explaining the operation of the infrared detection device according to the first embodiment of the present invention.

FIG. 3 is a timing chart explaining the operation of the infrared detection device according to the second embodiment of the present invention.

FIG. 4 is a timing chart explaining the operation of the infrared detection device according to the third embodiment of the present invention.

FIG. 5 is a timing chart explaining the operation of the infrared detection device according to the fourth embodiment of the present invention.

FIG. 6 is a timing chart explaining the operation of the infrared detection device according to the fifth embodiment of the present invention.

FIG. 7 is a block diagram showing a conventional infrared detector.

[Explanation of symbols] 1 Pyroelectric element 2 I / V conversion circuit 3a First voltage amplification unit 3b Second voltage amplification unit 4 output switching section 5 Popcorn noise detector 6 control circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-217231 (JP, A) JP-A-61-149887 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01V 8/12 G01J 1/44 G08B 13/191

Claims (5)

(57) [Claims] 1. A pyroelectric element, an I / V conversion circuit for converting a current signal output from the pyroelectric element into a voltage signal, and the I / V.
A first voltage amplification unit that amplifies the output of the conversion circuit, and a signal having a frequency higher than that of the first voltage amplification unit pass through the I voltage amplification unit.
A second voltage amplification unit for amplifying the output of the / V conversion circuit, and when the output of the second voltage amplification unit exceeds a predetermined value, it is determined that popcorn noise has occurred and popcorn noise detection is performed. A popcorn noise detection unit that outputs a signal, a control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit when the popcorn noise detection signal is output, and a control circuit from the control circuit. between said first voltage amplifier and the analog output terminal by the output, if you have a, and an output switching unit for switching the analog output is a detection signal from the first voltage amplifier into a signal other than the output the popcorn when a noise detection signal is output, the the analog output the pyroelectric element is a detection signal from the first voltage amplifier, and the I / V conversion circuit, the first voltage The output switching unit operates so as to switch to a reference potential inside a circuit including a width portion, a second voltage amplification unit, a popcorn noise detection unit, a control circuit, an output switching unit, and the like. It is that infrared detection device. 2. A pyroelectric element, an I / V conversion circuit for converting a current signal output from the pyroelectric element into a voltage signal, and the I / V.
A first voltage amplification unit that amplifies the output of the conversion circuit, and a signal having a frequency higher than that of the first voltage amplification unit pass through the I voltage amplification unit.
A second voltage amplification unit for amplifying the output of the / V conversion circuit, and when the output of the second voltage amplification unit exceeds a predetermined value, it is determined that popcorn noise has occurred and popcorn noise detection is performed. A popcorn noise detection unit that outputs a signal, a control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit when the popcorn noise detection signal is output, and a control circuit from the control circuit. between said first voltage amplifier and the analog output terminal by the output, if you have a, and an output switching unit for switching the analog output is a detection signal from the first voltage amplifier into a signal other than the output the popcorn when a noise detection signal is output, the the analog output the pyroelectric element is a detection signal from the first voltage amplifier, and the I / V conversion circuit, the first voltage The output switching unit works so as to switch to a GND signal inside a circuit including a width portion, a second voltage amplification unit, a popcorn noise detection unit, a control circuit, and an output switching unit. It is that infrared detection device. 3. A pyroelectric element, an I / V conversion circuit for converting a current signal output from the pyroelectric element into a voltage signal, and the I / V.
A first voltage amplification unit that amplifies the output of the conversion circuit, and a signal having a frequency higher than that of the first voltage amplification unit pass through the I voltage amplification unit.
A second voltage amplification unit for amplifying the output of the / V conversion circuit, and when the output of the second voltage amplification unit exceeds a predetermined value, it is determined that popcorn noise has occurred and popcorn noise detection is performed. A popcorn noise detection unit that outputs a signal, a control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit when the popcorn noise detection signal is output, and a control circuit from the control circuit. between said first voltage amplifier and the analog output terminal by the output, if you have a, and an output switching unit for switching the analog output is a detection signal from the first voltage amplifier into a signal other than the output the popcorn when a noise detection signal is output, the the analog output the pyroelectric element is a detection signal from the first voltage amplifier, and the I / V conversion circuit, the first voltage And width portion, you and the second voltage amplifier, and a popcorn noise detection unit, a control circuit, so as to switch to an external power source circuit and an output switching section or the like, characterized in that the output switching unit acts infrared detection device. 4. A pyroelectric element, an I / V conversion circuit for converting a current signal output from the pyroelectric element into a voltage signal, and the I / V.
A first voltage amplification unit that amplifies the output of the conversion circuit, and a signal having a frequency higher than that of the first voltage amplification unit pass through the I voltage amplification unit.
A second voltage amplification unit for amplifying the output of the / V conversion circuit, and when the output of the second voltage amplification unit exceeds a predetermined value, it is determined that popcorn noise has occurred and popcorn noise detection is performed. A popcorn noise detection unit that outputs a signal, a control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit when the popcorn noise detection signal is output, and a control circuit from the control circuit. between said first voltage amplifier and the analog output terminal by the output, if you have a, and an output switching unit for switching the analog output is a detection signal from the first voltage amplifier into a signal other than the output When a popcorn noise detection signal is output, an analog output which is a detection signal from the first voltage amplification unit is output,
In the circuit including the pyroelectric element, the I / V conversion circuit, the first voltage amplification section, the second voltage amplification section, the popcorn noise detection section, the control circuit, the output switching section, etc.,
As switch to the output of the oscillation circuit is provided an oscillation circuit, infrared detector you characterized in that the output switching unit acts. 5. A pyroelectric element, an I / V conversion circuit for converting a current signal outputted from the pyroelectric element into a voltage signal, and the I / V.
A first voltage amplification unit that amplifies the output of the conversion circuit, and a signal having a frequency higher than that of the first voltage amplification unit pass through the I voltage amplification unit.
A second voltage amplification unit for amplifying the output of the / V conversion circuit, and when the output of the second voltage amplification unit exceeds a predetermined value, it is determined that popcorn noise has occurred and popcorn noise detection is performed. A popcorn noise detection unit that outputs a signal, a control circuit that performs signal control on an analog output that is a detection signal from the first voltage amplification unit when the popcorn noise detection signal is output, and a control circuit from the control circuit. between said first voltage amplifier and the analog output terminal by the output, if you have a, and an output switching unit for switching the analog output is a detection signal from the first voltage amplifier into a signal other than the output If the popcorn noise detection signal is output, the first analog output as switching to an open state is detection signal from the voltage amplifier, the output switching unit acts Door infrared detection device shall be the features a.