JPH0430558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a body-sensitive automatic load actuation device using a pyroelectric infrared sensor.

In recent years, pyroelectric sensors have attracted attention because they do not require a light emitting section and are easier to handle than other optical sensors, and are rapidly being used. Pyroelectric infrared sensors have a flat response to light wavelengths and have no so-called wavelength dependence, so they detect infrared rays with a wavelength of 5 to 10 μm emitted from the body and can automatically open and close doors, etc. It has already been put into practical use in security devices such as security devices and door phones. On the other hand, attempts have been made to use this function to construct human body-sensitive automatic lighting devices such as electric lights, but in reality, the cost of the timing circuit and the electric light switching section is high, and it has not been possible to obtain a satisfactory product. Ta.

The present invention was made in view of the above points, and utilizes the body-sensitive characteristics of a pyroelectric infrared sensor, and focuses on the fact that the thermal response of a shape memory alloy constitutes a type of timekeeping circuit. A sensitive automatic load actuation device is provided.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention, and in the figure, reference numeral 1 indicates an infrared sensing section using a pyroelectric infrared sensor. This sensing section 1 has functions such as a parabolic condenser and a condensing lens that condense infrared rays emitted from the body onto a pyroelectric infrared sensor, and can be easily constructed using well-known technology. When the AC voltage of 100V or 200V of commercial power is supplied to the input terminal of the power supply section 2, the voltage is converted into a DC voltage and supplied to the infrared sensing section 1 and the signal amplification section 3.
The signal amplification section 3 has a capacitor-coupled amplification section at the input stage and constitutes a high-frequency cutoff active filter, and constitutes a bandpass type filter that can cope with pop noise, dark current, and external noise. The bandwidth of this filter is chosen to suit the monitoring distance, angle, and application of the active loads such as porch lights, footlights, kitchen lights, toilet lights, etc. In addition, this amplifying section 3
It is also possible to add an extraneous light cutoff circuit to the system to prevent lights from turning on during the day. 4 is a time constant circuit, which is an important component of the present invention. This time constant circuit 4 is an important part inserted to compensate for the drawback of the pyroelectric infrared sensor, that is, poor followability, and is an unresolved structural requirement depending on the usage mode. . For example, in the case of footlights and stairway lights, where there is a lot of traffic and relatively few people have to stop, it is sufficient to ensure a short lighting retention time; In cases where people move slowly, such as with street lamps, it is necessary to extend the lighting retention time to some extent to compensate for the drawback of the pyroelectric infrared sensor that a stationary signal cannot be obtained. In the present invention, the time constant of the time constant circuit 4 can be set to match various uses and modes of use, thereby eliminating the drawbacks of the pyroelectric infrared sensor. Reference numeral 5 denotes an external load circuit connected to the apparatus of the present invention, and although not limited to this, lamp, fluorescent lamp, and buzzer circuits are mainly suitable for the present invention. Mechanical contacts are preferable for switching means that are commonly compatible with such various loads, although there is a problem with their longevity.

FIG. 2 is a specific circuit connection diagram of the device of the present invention shown in FIG. 1, in which parts corresponding to those in FIG. 1 are given the same reference numerals. The signal amplification section 3 is composed of an active filter amplification section 3-1 at the front stage and a comparator section 3-2 at the rear stage, and has the function of discriminating signal levels obtained by body movements.

The amplifier section 3-1 inputs the output from the sensing section 1 to the positive terminal of the operational amplifier OA ₁ via the capacitor Co and the resistor Ro, and the output voltage of the amplifier OA ₁ is connected to the resistor R ₁ .
_R2 is grounded and its connection point is resistor
Connect to the negative terminal of amplifier OA ₁ through R ₃ and resistor
Connect capacitors C ₁ and C ₂ in parallel to R ₁ and R ₂ ,
The amplification section as a whole constitutes a bandpass filter. In addition, the comparator section 3-2 inputs the output of the amplifier OA ₁ to the positive terminal of the operational amplifier OA ₂ via the resistor R ₄ , and also feeds back the output of the amplifier OA ₂ to the positive terminal via the resistor R ₅ for systeresis. It constitutes a comparator with characteristics. Comparator section 3
The output signal from -2 is supplied to the base of power transistor 6 via a resistor. Although an NPN type is used as the power transistor 6 in the illustrated embodiment, a PNP type may also be used, and this selection is preferably made appropriately depending on the polarity of the signal, the signal level, and the value of the power supply voltage. . A time constant circuit 4, which will be described in detail later, is connected to the collector circuit of the power transistor 6, and a light receiving element 7 is connected between the collector and the output terminal of the comparator section 3-2. It constitutes a feedback circuit. The emitter of the power transistor 6 and the time constant auxiliary element 8 are connected to ground via, for example, a thermistor. Note that as the light receiving element 7, an optical negative resistance element, mainly a CdS element, is used in this embodiment, but it goes without saying that other devices can be used without departing from the spirit of the present invention.

As described above, the external load circuit 5 in which a lamp, fluorescent lamp, buzzer, etc. are used is connected to an AC 100-200 V power source through the switching contact terminals C and D of the time constant circuit 4. Of course, it may be connected to any other desired power supply or power supply circuit. The external load circuit 5 is connected to a power supply and used singly or in combination. Thus, when the contact of the time constant circuit 4 is closed, desired power is supplied from the power supply to the load circuit 5, and the load is operated.

FIG. 3 shows a specific example of the time constant circuit 4.
Figure A shows a case where a shape memory alloy 21 formed in a spiral shape is used. An electrical insulating film 22 made of resin or the like is applied on the helical shape memory alloy 21, one end of which is welded, for example, to a contact terminal C, and a contact material 23, such as platinum rhodium gold, is caulked to the other end. In addition, a heating element 2 is provided on the outer periphery of the shape memory alloy 21.
4. In this example, wind a 0.2φmm nichrome wire cut to a length that provides a resistance value of about 150Ω,
One end A is connected to the collector of the power transistor 6, and the other end B is connected to a predetermined DC power supply +B. Further, a contact spring 25 is provided at a predetermined distance from the contact material 23, and a contact terminal D is formed in a portion of this contact spring 25. As shown in FIG. 3, the contact terminal C is connected to the load circuit 5, and the contact terminal D is connected to the AC power source, so that the power transistor 6 becomes conductive and a current flows through the heating element 24, causing the shape memory alloy 21 is heated to reach a predetermined set temperature, the shape memory alloy 21 returns to its memorized shape, the contact material 23 comes into contact with the contact spring 25, and the electric circuit contact terminals C and D are closed. In this way, the required power is supplied to the load circuit 5, and the load is activated.

FIG. 3B shows another specific example of the time constant circuit 4, in which a bimetallic shape memory alloy is used. In the figure, 31 indicates a bimetal shape memory alloy, and the thermal expansion coefficient of the metal member 311 on which the contact material 32 is attached is the same as that of the other metal member 311.
12, and therefore the heater 33
When the contact material 32 of the metal member 311 is heated by the contact springs 34 arranged at predetermined intervals,
The contact material 35 is brought into contact with the contact material 35 to close the contact terminal C-D.

Next, the operation of the body-sensing automatic load actuation device according to the present invention having the above configuration will be explained.

First, 5 to 10 μm (peak value) emitted from the body.
Infrared rays 9 having a wavelength of 9.36 μm are incident on the infrared sensing section 1. Normally, people move at a speed of 1 m/s or less, so the frequency characteristic of the output waveform obtained from the infrared sensing section 1, which uses a pyroelectric infrared sensor and is composed of a mirror with an aperture diameter of about 40 mm, is 0.1 to 50.
below Hz. In one embodiment of the present invention, the passband width of the active filter amplifying section 3-1 is set to 0.1 Hz or more and 100 Hz or less to pass the power supply ripple of 50 Hz (60 Hz), and each constant is set to obtain a gain of about 60 dB. ing. Therefore, the infrared rays 9 emitted from the body sensed by the infrared sensing section 1 pass through this active filter amplification section 3-1 and are amplified.
The signal is supplied to the comparator section 3-2. The output level from the active filter amplifier section 3-1 set as described above was 100 mV or more. The comparator section 3-2 is set to give an output signal when the input signal is at a level of 100 mV or higher, and not to give an output signal when the level is lower than 100 mV. Therefore, the infrared rays 9 emitted from the body are transmitted from the active filter amplifier 3-1 as described above.
Since the output signal has a level of 100 mV or higher and is applied to the comparator section 3-2, the sensed output signal from the comparator section 3-2 is applied to the power transistor 6 constituting the power amplifier. Thus, the power transistor 6 becomes conductive, and current flows through the heating element 24 or heater 33 of the time constant circuit 4.
Shape memory alloy 21 or 31 is heated.

By the way, the sensing output signal from the comparator section 3-2 is only suitable for the human body from which power supply ripple noise, pop noise, unnecessary moving body noise, etc. are completely removed due to the high level of this signal and the frequency band limitation. It becomes a sensitive pulse wave. In conventional devices, this sensing signal is fed to a CR integrator circuit to perform a timing function and set the operating time of a lamp or other load. However, with these conventional methods, when the movement of a person is slow, or when the movement of a person temporarily stops, such as in a bathroom light, etc., it is necessary to turn on the light continuously for a certain period of time. , the CR constant of the time constant circuit must be increased, and the shape of the capacitor must be increased in order to continue lighting for several minutes, resulting in various inconveniences such as hindering miniaturization of the device.

Therefore, in the present invention, as described above, the time constant circuit 4 is constituted by a thermal time constant circuit using a shape memory alloy, and the sensing output signal supplied to the power transistor 6 is thermally converted, and the shape memory alloy 21
Or, it was configured to store heat in 31. That is, when the shape memory alloy 21 or 31 is heated, it returns to its original shape, and the contact material 23 contacts the contact spring 25, or the contact material 32 contacts the contact material 35, and a closed circuit is established. form,
Supply a predetermined amount of power to the load. In this case, since the thermal response of the shape memory alloy is determined by its heat capacity, a time constant circuit with a long time constant can be easily obtained. Such a thermal time constant circuit has the advantage of being constructed from a small shape memory alloy.

On the other hand, when external light is poured into the light receiving element 7 as during the daytime, the resistance characteristic of the light receiving element 7 composed of CdS system exhibits a photo-negative resistance.
The resistance value of this element 7 decreases, and when the transistor 6 is turned on, the amount of negative feedback of this transistor 6 increases, the current value decreases, and the shape memory alloy is not heated much. Therefore, the shape memory alloy does not return to its original shape, the contact material 23 or 32 does not come into contact with the contact spring 25 or the contact material 35, a closed circuit is not formed, and power is not supplied to the load circuit 5. In other words, during daytime, loads such as lamps are not operated;
It is possible to prevent wasteful power consumption.

In the above embodiment, the human body sensing signal is amplified to a level higher than the reference level of the comparator section 3-2 of the signal amplification stage 3, and a positive output signal is supplied from the comparator section 3-2 to the base of the transistor 6, In addition, the shape memory alloy exhibits the characteristic of elongating and returning to its original shape when heated, and the structure is configured to close the contact and supply power to the load, but conversely, when there is no signal, the transistor 6 is held in a conductive state, If the shape memory alloy is constructed so that it contracts when heated and expands and returns to its original shape when cooled, and the transistor 6 is turned off by a human body sensing signal, the human body sensing signal can be When input, heating of the shape memory alloy is stopped and the memory alloy is expanded so that the contacts are closed and configured to provide power to the load. In this case, the light receiving element 7 is
As shown in FIG. 4, the collector circuit of the transistor 6 may be connected in series with the time constant circuit 4.

As described in detail above, the present invention compensates for the insensitivity characteristic of the pyroelectric infrared sensor due to its slow operation by using a thermal time constant circuit, and even after the electrical signal from the pyroelectric infrared sensor stops, Depending on the setting, it is possible to supply power to the load circuit for a fixed period of time, and according to the present invention, compared to the conventional case where the timekeeping function is performed by a CR integration circuit, A compact and inexpensive body-sensitive automatic load actuation device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the body-sensing automatic load actuation device according to the present invention, and FIG.
Specific circuit connection diagram of the device shown in the figure, Figure 3 A and B
4 is a perspective view and a side view showing a specific example of a time constant circuit used in the device of the present invention, and FIG. 4 is a partial circuit diagram showing a modification of the device of the present invention. In the figure, 1 is an infrared sensing section, 2 is a power supply section, 3 is a signal amplification section, 3-1 is an active filter amplification section,
3-2 is a comparator section, 4 is a time constant circuit, 5 is an external load circuit, 6 is a power transistor, 7 is a light receiving element, 8 is a time constant auxiliary element, and 21 and 37 are shape memory alloys.

Claims (1)

[Claims] 1. An infrared sensing section using a pyroelectric infrared sensor that detects infrared rays emitted from the body and generates an electrical signal, and generates heat in response to the electrical signal from the infrared sensing section, and the heat generation causes shape memory. The alloy is returned to its original shape, and the electrical contacts attached to the shape memory alloy are brought into contact with the opposing contacts to supply a predetermined amount of power to an external load circuit, and after the heat generation has stopped, the shape is restored after a certain period of time. and a time constant circuit that causes the memory alloy to deform again and release the contact between the contact attached to the shape memory alloy and the opposing contact to stop supplying power to the external load circuit. Features a body-sensing automatic load actuation device.