JPH07174627A - Pyroelectric infrared detector - Google Patents

Abstract

PURPOSE:To let the user of a pyroelectric infrared detector which is inhibited from outputting during its warming-up time to be informed that the detector is in an output inhibiting state for a prescribed period of time (warming-up time) after power supply is made to the detector. CONSTITUTION:The pyroelectric infrared detector is provided with a pyroelectric sensor 2, output circuit 6 which outputs to an external device, a timer 9 which inhibits the circuit 6 from outputting for a prescribed period of time equal to or longer than the circuit stabilizing time after power supply is made to the detector, and initial output inhibiting time zone informing circuit 19 which operates based on the output of the timer 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared detecting device used for lighting an illuminating device for a certain period of time based on human body detection.

[0002]

2. Description of the Related Art An example in which a conventional pyroelectric infrared detection device is applied to control an illumination device is shown in FIGS.
FIG. 4 is a block diagram, and FIG. 5 is a circuit diagram around the pyroelectric sensor.

In FIG. 4, 1 is an optical system, 2 is a pyroelectric sensor for detecting a human body, 3 is an amplifier circuit, 4 is a level discrimination circuit,
Reference numeral 5 is an off-delay timer, 6 is an output circuit, 7 is a lighting device, 8 is a power supply circuit, 9 is an initial timer, and 10 is an output inhibition circuit.

The pyroelectric sensor 2, the amplification circuit 3, the level discrimination circuit 4, the off-delay timer 5, the output circuit 6 and the illuminating device 7 are connected to a power supply circuit 8 and are supplied with power. In FIG. 5, 11 is a pyroelectric element, 12 is an electrode, 1
3, 14 are resistors, 15 are noise removing capacitors, 16
Is an OP amplifier. Instead of the noise removing capacitor 15, a noise removing capacitor 15 'is provided at a position indicated by a dotted line.
May be connected.

Next, the normal operation of the conventional pyroelectric infrared detector for lighting control will be described with reference to the right half of the time chart of FIG.

When infrared rays emitted from the human body are incident on the pyroelectric element 11 as shown in FIG. 3B, the spontaneous polarization value changes in the pyroelectric element 11, and the resistance 13 is applied to the resistor 13 as shown in FIG. Excitation current flows. In the initial stage of human body detection, a current in the positive direction flows through the resistor 13, and a current in the reverse direction flows through the resistor 13 as the state of the pyroelectric element 11 is balanced. This excitation current is O
It is amplified by the P amplifier 16, the level is discriminated by the level discrimination circuit 4, and when it exceeds the threshold level, it is output to the off-delay timer 5. The output from the level discrimination circuit 4 causes the off-delay timer 5 to output to the output circuit 6 for a fixed time T ₁ (off-delay time) as shown in FIG. Therefore, the lighting device 7 is also turned on for a certain period of time T ₁ as shown in FIG.

Next, the operation when the power is turned on will be described with reference to the left half of the time chart of FIG.

The noise removing capacitor 15 is intended to prevent noise from being mixed into the output of the OP amplifier 16, but the noise removing capacitor 15 makes the circuit unstable when the power is turned on. . Further, as a characteristic of the pyroelectric element 11, the spontaneous polarization value fluctuates when the power is turned on, and a very unstable excitation current flows through the resistor 13 as shown in FIG. An output is generated from the OP amplifier 16. The instability of the output when the power is turned on usually continues for 20 to 30 seconds.

Since there is such an output instability when the power is turned on, if the initial timer 9 and the output prohibition circuit 10 are not provided, from the time when the power is turned on, that is, the circuit stabilization time T ₀ , An unstable output signal is output from the off-delay timer 5 to the output circuit 6, and the lighting device 7 is in a state in which lighting and extinguishing are repeated in an unstable manner.

Such an unstable repetition of turning on and off is very uncomfortable for the user.

Therefore, the initial timer 9 and the output prohibiting circuit 10
Is provided so that the output of the output circuit 6 is prohibited for a predetermined time (warm-up time) T _{2 which is} equal to or longer than the circuit stabilization time T ₀ after the power is turned on.

By this, it is possible to prevent the unstable turning on and off of the illuminating device 7 when the power is turned on, that is, flicker.

[0013]

However, the conventional example having such a structure has the following problems.

That is, for the user, the pyroelectric infrared detector is in the warm-up time T ₂ and the lighting device 7 can be turned on when the warm-up time T ₂ elapses. I cannot recognize that it has become.

Therefore, conventionally, the user has timed or actually operated the pyroelectric element 11 to determine whether or not the lighting device 7 is turned on. But,
It took a lot of work to do that.

Further, it was very inconvenient because it was sometimes mistakenly recognized as a failure of the pyroelectric infrared detector without noticing that it was in the warm-up time T ₂ .

The present invention has been made in view of the above circumstances, and in a pyroelectric infrared detection device having a structure in which output is prohibited during warm-up time, power is turned on. It is an object of the present invention to enable the user to be notified that the output is prohibited for a predetermined time (warm-up time).

[0018]

The present invention has the following constitution in order to achieve such an object.

That is, the pyroelectric infrared detector of the present invention is
A pyroelectric sensor, an output circuit for outputting to an external device, an initial timer that inhibits the output of the output circuit for a predetermined time longer than the circuit stabilization time from the time of power-on, and an initial timer that operates based on the output from this initial timer. An output prohibition time zone notification circuit is provided.

[0020]

The operation of this structure is as follows.

That is, when the power is turned on, the initial timer operates and the output from the output circuit is prohibited for a predetermined time from the time when the power is turned on, and the initial timer drives the initial output prohibited time zone notification circuit to reset the initial time. Notification that the output prohibition time zone is in effect.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram of a pyroelectric infrared detection device according to an embodiment of the present invention.

In FIG. 1, the same reference numerals as those shown in FIG. 4 according to the conventional example refer to the same parts and portions as those shown in the present embodiment.

Further, unless otherwise specified, the present embodiment and the conventional example have the same structure in connection relation.

In the block diagram of this embodiment, the configuration different from the conventional example is as follows.

A multivibrator 17 is connected to an initial timer 9 at the next stage of the power supply circuit 8, and an LED (light emitting diode) 18 as an example of a lamp is connected to an output terminal of the multivibrator 17. This multi-vibrator 1
The LED 7 and the LED 18 constitute the initial output prohibited time zone notification circuit 19 in the configuration of the invention. Multi vibrator 1
7 and the LED 18 are connected to the power supply circuit 8 and are supplied with power.

Since the other structure of the block circuit is the same as that of the conventional example, the description thereof will be omitted.

The circuits of the initial timer 9, the multivibrator 17, and the LED 18 are constructed as shown in FIG. The circuit configuration will be described below.

The initial timer 9 is composed of resistors R1 to R3, a capacitor C1 and a comparator 20.

The multivibrator 17 includes resistors R4 to R4.
7, capacitors C2, C3 and transistor Tr1,
It is composed of Tr2.

The base of the transistor Tr2 is connected to the comparator 20 via the diode D1. LED1 is connected to the collector of the transistor Tr1 via the resistor R7.
8 is connected.

Next, the operation of this embodiment when the power is turned on will be described with reference to the time chart of FIG.

When the power is turned on as shown in FIG. 3A, the pyroelectric sensor 2 is shown for a certain time as shown in FIG.
Although an unstable excitation current is generated at the same time, as shown in FIG. 6D, there is an output from the initial timer 9 to the output prohibition circuit 10 at the same time when the power is turned on, and this output continues for the warm-up time T ₂ . Therefore, during this warm-up time T ₂ ,
Output from the output circuit 6 to the lighting device 7 is prohibited.

On the other hand, when the power is turned on, it is also output from the initial timer 9 to the initial output prohibited time zone notification circuit 19,
As shown in Figure (G), during the warm-up time T ₂ , the LED
18 lights up. Thus, the user can know that the pyroelectric infrared detection device is a time zone of warm-up time T _2.

The detailed operation of the initial output prohibited time zone notification circuit 19 will be described below.

When the power is turned on by turning on the switch Sw, the multivibrator 17 oscillates.

That is, when the transistor Tr2 is off and the transistor Tr1 is on, a current flows through the LED 18 and the LED 18 emits light. And the capacitor C
The charge of 2 starts discharging and the capacitor C3 starts to be charged. When the charging voltage of the capacitor C2 becomes lower than the base-emitter voltage of the transistor Tr1 and the charging voltage of the capacitor C3 becomes higher than the base-emitter voltage of the transistor Tr2, the transistor Tr
1 is turned off, and the transistor Tr2 is turned on. When the transistor Tr1 is turned off, no current flows in the LED 18, and the LED 18 is extinguished.

When the transistor Tr1 is turned off and the transistor Tr2 is turned on, the charge of the capacitor C3 starts discharging and the capacitor C2 starts to be charged. The charging voltage of the capacitor C3 is the transistor T
When it becomes lower than the base-emitter voltage of r2 and the charging voltage of the capacitor C2 becomes higher than the base-emitter voltage of the transistor Tr1, the transistor Tr2 is turned off and the transistor Tr1 is turned on. When the transistor Tr1 is turned on, a current flows through the LED 18,
The LED 18 emits light.

By repeating the above operation, the multivibrator 17 oscillates and the LED 18 flickers as shown in FIG.

On the other hand, when the switch Sw is turned on, the voltage divided by the resistors R1 and R2 is applied to the positive input terminal of the comparator 20 and becomes the reference voltage. Further, the charging of the capacitor C1 is started via the resistor R3, and the charging voltage thereof gradually rises. The charging voltage of the capacitor C1 is input to the negative input terminal of the comparator 20, and the output terminal of the comparator 20 is at "H" level until the input voltage exceeds the reference voltage. Therefore, the diode D1 does not conduct and the oscillation of the multivibrator 17 is continued.

However, when the charging voltage of the capacitor C1 exceeds the reference voltage of the comparator 20, the output terminal of the comparator 20 becomes "L" level, so that the diode D1 conducts and the transistor Tr2 is fixed in the cutoff state. .
That is, the oscillation of the multivibrator 17 is stopped.

When the transistor Tr2 is fixed in the cutoff state, the conduction state of the transistor Tr1 is continued and L
The ED 18 stops the flicker state up to that point and shifts to a state in which it always emits light.

The time at which the charging voltage of the capacitor C1 exceeds the reference voltage of the comparator 20 depends on the time constant determined by the resistor R3 and the capacitor C1. That is, this time constant is the warm-up time T ₂ by the initial timer 9. Then, during the warm-up time T ₂ , the LED 18 flickers as shown in FIG.

The flicker of the LED 18 enables the user to reliably and easily recognize that the pyroelectric infrared detector is in the warm-up time zone. Further, it is possible to know that the pyroelectric infrared detection device is in the active state by constantly emitting the light from the LED 18.

The operation based on the human body detection is the same as that of the conventional example, and therefore its explanation is omitted.

The initial output prohibited time zone notification circuit may be a circuit that simply turns on a lamp such as an LED. Further, it may be a sounding device such as a buzzer.

[0047]

As described above, according to the present invention, it is possible to clearly and easily notify that the output from the output circuit is in the prohibited state because of the warm-up time.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of a multivibrator, an initial timer and its peripheral circuits according to an embodiment of the present invention.

FIG. 3 is a time chart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example device.

FIG. 5 is a circuit diagram around a pyroelectric sensor in a conventional device.

FIG. 6 is a time chart for explaining the operation of a conventional example.

[Explanation of symbols]

 2 Pyroelectric sensor 5 Off-delay timer 6 Output circuit 9 Initial timer 17 Multivibrator 18 LED (lamp) 19 Initial output prohibited time zone notification circuit

Claims (1)

[Claims] 1. A pyroelectric sensor, an output circuit for outputting to an external device, an initial timer for prohibiting the output of the output circuit for a predetermined time longer than a circuit stabilization time from the time of power-on, and an output from the initial timer. A pyroelectric infrared detection device including an initial output prohibited time zone notification circuit that operates based on the above.