JPH037890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an infrared detection device for detecting, for example, the temperature of an object to be detected based on infrared rays emitted by the object.

(b) Prior Art In recent infrared detection devices for detecting the temperature of an object to be detected, for example, a pyroelectric infrared detector is built into the infrared detection section.

Such an infrared detector has the property of generating an alternating current signal based on the amount of change in incident infrared radiation, and the detection accuracy of the infrared detector improves as the amount of incident infrared rays changes more periodically. It is necessary to periodically interrupt the infrared rays incident on the infrared detector, and for this purpose, as shown in FIGS. A board chopper 3 is arranged. Such a configuration is also shown in Japanese Patent Publication No. 10467/1983.

However, such a chopper 3 has a large shape and there is a space problem, and the motor 2 has uneven rotation and does not necessarily rotate the chopper 3 periodically, resulting in a decrease in detection accuracy.

Furthermore, as can be seen in Japanese Patent Publication No. 53-10467 or as will be understood from the explanation below, the AC signal output from the infrared detector 1 depends on the intermittent cycle of the infrared rays incident on the infrared detector 1. It is necessary to synchronize and perform synchronous detection. That is, for this purpose, it is necessary to separately provide a synchronous pulse generator that generates synchronous pulses based on the rotation of the motor 2.

However, when installing such a synchronous pulse generator, there is a drawback that the configuration of the infrared detection device becomes complicated.

(c) Object of the invention The object of the invention is to miniaturize and simplify an infrared detection device, and to enable infrared detection with high precision.

(iv) Structure of the Invention In order to achieve the above object, the structure of the present invention includes an infrared detector that generates an alternating current signal according to the amount of change in incident infrared rays, which is arranged alternately in a direction perpendicular to the direction of displacement. A pair of opposing bodies having a plurality of linear infrared passing parts and infrared non-passing parts and located in a region through which infrared rays from a detected object pass to be incident on the detected object; A state in which the parts and infrared non-passing parts substantially overlap each other, and a state in which the infrared passing part and infrared non-passing part of one opposing body substantially overlap with the infrared passing part and infrared passing part of the other opposing body, respectively. , a vibrating body that vibrates to periodically repeat , a pulse signal generator that generates a periodic pulse signal to vibrate the vibrating body, and a pulse signal generator that receives the pulse signal generated by the generator. , a synchronous detector for synchronously detecting the alternating current signal from the infrared detector based on the signal.

(e) Embodiment An infrared detection device according to an embodiment of the present invention will be described below.

FIG. 2 shows the infrared detector 4 of the device, 5 is a pyroelectric infrared detector made of lithium tantalate (LiTaO ₃ ) single crystal and generates an alternating current signal according to the amount of change in incident infrared rays, 6 and 7 8 is a metal support made of copper, phosphor bronze, etc., and the back electrode 7 is formed on the front and back surfaces of the infrared detector, respectively. The infrared detector 5 is fixed to the upper surface of the support base 8 with a conductive adhesive 9 such as silver paste.

10 is an alumina substrate; 11 is an impedance conversion circuit disposed on the substrate; since the infrared detector 5 has a high resistance, an impedance conversion circuit is used to convert the high resistance into a low resistance; 12 is a metal cap 13; The storage body includes a header 14, and on the header 14 inside the storage body, a support base 8 on which the detection body 5 is fixed and a substrate 10 on which the impedance conversion circuit 11 is arranged are fixed. Reference numeral 15 denotes a ground terminal that is directly implanted in the header 14, and this terminal is electrically connected to the back electrode 7 via the support base 8 and adhesive 9. 16 and 17 are first and second lead terminals implanted in the header 14 via insulating materials 18 and 19, respectively; 20 are lead wires connecting the surface electrode 6 and the impedance conversion circuit 11; 21 and 22; is the impedance conversion circuit 11 and the first and second lead terminals 16 and 17.
This is the lead wire that connects the

Reference numeral 23 denotes an opening formed in the cap 13 to allow infrared rays to enter the infrared detector 5 from the surface electrode 6 side, and the opening is circular with a diameter of 8 mm.
It has a square or rectangular shape. 24 is a first infrared transmitting body which has the same shape as the opening 23 and closes the opening 23, and the transmitting body has a growth rate of 2 to 5 μm.
Thickness of several 100 μm with high transmittance to infrared rays
It is made of silicon or germanium plate.
Note that the first infrared transmitting body 24 and the infrared detecting body 5
The distance T is 500 μm to 3 cm. 25
are a plurality of linear first infrared ray transmissive bodies made of a material that does not pass infrared rays such as aluminum, gold, silver, etc., and extend in a direction perpendicular to the plane of the paper on the lower surface of the first infrared transmissive body 24; Body width W is 1μm~2
mm, and the thickness D is 0.1 to 100 μm. Further, the first infrared ray blocking bodies 25 are spaced apart from each other by a predetermined dimension t, and the dimension t is the same as the width W. The portions corresponding to the dimension t serve as a plurality of first infrared passing portions.

26 is a distance d (=
0.1 μm to 1 cm) and the first infrared transmitting body 2
4, the second infrared transmitting body is located close to and opposite to the opening 2, which is similar to the first infrared transmitting body 24.
It has the same shape as No. 3 and is made of a silicon or germanium plate several 100 μm thick that has high transmittance to infrared rays with a wavelength of 2 to 15 μm. Reference numeral 27 denotes a plurality of linear second infrared non-transmitting bodies extending in the same direction as the first infrared transmitting body 25 (perpendicular to the plane of the paper) on the upper surface of the second infrared transmitting body 26. The body is made of an infrared ray blocking material such as aluminum, gold, silver, etc., like the first infrared ray blocking body 25, and the width W' of the second infrared ray blocking body 27 is 1 μm to 1 μm.
2 mm, and the thickness D' is 0.1 to 100 μm. Furthermore,
The second infrared non-passing body 27 has a predetermined size with respect to each other.
t′, and the dimension t′ is the above width.
It is the same as the dimension of W′. The portions corresponding to the dimension t' serve as a plurality of second infrared passing portions.

Reference numeral 28 denotes a vibrating body, ie, a bimorph, formed by pasting together two piezoelectric plates.The bimorph is fixed at its lower end to an insulating stand 29 provided on the header 14, and at its upper end is the second infrared transmitting body 26. is attached. The shape of the bimorph 28 is a rectangular parallelepiped, the height h is 1 to 3 mm, and the thickness a is 50 μm.
m~5mm, width (dimension perpendicular to the page) 0.5~
It is 15mm. The bimorph 28 includes crystal, Rothsiel salt, ethylene tartrate, diamine,
Single crystals such as potassium tartrate, potassium monophosphate, ammonium monophosphate, lithium sulfate, barium titanate, glycine sulfate, barium titanate porcelain,
It is made of porcelain materials such as zirconate/lead titanate porcelain and niobate porcelain. Reference numerals 30 and 31 denote third and fourth lead terminals which are respectively implanted in the header 14 via insulating materials 32 and 33, and these lead terminals are connected to electrode pads 34 and 35 formed on both sides of the bimorph 28, respectively. is connected to.

Therefore, between the electrode pads 34 and 35, a third
When an AC drive signal with a predetermined amplitude and a predetermined frequency is applied via the fourth lead terminals 30 and 31, the bimorph 28 is bent in accordance with the frequency of the AC drive signal, and the second infrared transmitting body 26 is periodically moved in the direction of arrow A. vibrate, thereby causing the first and second infrared ray non-passing bodies 25 and 27 to overlap each other and the first and second infrared passing parts to overlap each other (the state shown in FIG. 2).
and a first infrared passing section and a first infrared non-passing body 2
5, the state in which the second infrared ray non-passing body 27 and the second infrared ray passing section overlap are periodically repeated.

At this time, the infrared rays from the object to be detected outside the infrared detector 4 are periodically incident on the infrared detector 5, that is, the infrared rays that are incident on the infrared detector 5 are periodically changed. The body 5 generates an alternating current signal according to the amount of change. More specifically, the alternating current signal outputted by the detection body 5 is as follows:
It has an amplitude based on the temperature difference between the temperature of the object to be detected and the room temperature, and has the same frequency as the AC drive signal applied to the bimorph 28.

FIG. 3 shows another infrared detector 4s, in which the second infrared transmitting body 26s is connected to the housing 1.
2 and closely facing the first infrared transmitting body 24. In this figure, the same parts as those in FIG. 1 are given the same numbers, and the same parts as in FIG. 1 are given the same numbers with a suffix s.

FIG. 4 shows a circuit of an infrared detection device including the infrared detector 4 or 4s, and the impedance conversion circuit 11 in the infrared detector 4 or 4s has an impedance of 10 ¹⁰ to
It is formed by a high input resistor 36 of 10 ¹¹ Ω, an FET (field effect transistor) 37, and an output resistor 38 of about 10 kΩ.

The infrared detector 4 or 4s is supplied with a DC voltage through a first lead terminal 16, and has an amplitude corresponding to the temperature difference between the temperature of the object to be detected and the room temperature from a second lead terminal 17, and has an amplitude corresponding to the temperature difference between the temperature of the object to be detected and the room temperature. An AC signal having the same frequency as the drive signal applied to 28 is output. 39 is a diode for measuring room temperature; 40 is a pulse oscillator made of an astable multivibrator and oscillates periodic pulses; 41 is a pulse oscillator that generates periodic pulses based on the pulses;
42, 43, 44 are DC amplifiers, 45 is a filter amplifier, 46 is a synchronous detector, and 47 is a synthesis circuit. , 48 are output terminals.

Therefore, these DC amplifiers 42, 43, 44,
The operations of the filter amplifier 45, synchronous detector 46, and combining circuit 47 are similar to those of the circuit shown in Japanese Patent Publication No. 53-10467, but the operations of the synchronous detector 46 and combining circuit 47 will be described in detail. The synchronous detector 46 inputs the pulses from the oscillator 40 and operates to synchronously detect the AC signal from the detection object 5 that has passed through the filter amplifier 45 based on the pulses. That is, in this case, in the synchronous detector 46, the pulse from the oscillator 40 coincides with the positive or negative half cycle of the AC signal from the detection object 5. When the temperature of the object to be detected is higher than the room temperature, the above pulse corresponds to the positive half cycle of the AC signal from the object to be detected 5, and when the room temperature is higher than the temperature of the object to be detected, the above pulse is detected. It is designed to coincide with the negative half cycle of the AC signal from the body 5. In the former case, the synchronous detector 46 detects a positive DC signal corresponding to the amplitude value of the AC signal (the signal represents the difference between the temperature of the object to be detected and the room temperature and the amplitude value of the object to be detected). In the latter case, it outputs a negative DC signal corresponding to the amplitude value of the AC signal (the signal represents the same temperature difference and is lower than the temperature of the detected object). ) is output.

Next, the combining circuit 47 connects the diode 39
DC signal from (the signal represents room temperature)
Based on this, the output of the synchronous detector 46 is operated to correct the room temperature. That is, when the temperature of the object to be detected is higher than the room temperature, a positive DC signal from the synchronous detector 46 corresponding to the difference between the temperature of the object to be detected and the room temperature,
A DC signal from the diode 39 corresponding to the room temperature is added, and thereby the synthesis circuit 47 outputs a DC signal corresponding to the actual temperature of the object to be detected.
Also, if the temperature of the object to be detected is lower than room temperature,
Similarly, the diode 3 is connected to the negative DC signal from the synchronous detector 46 according to the difference between the temperature of the detected object and the room temperature.
In other words, the DC signal representing the temperature difference is subtracted from the DC signal representing the room temperature, so that the combining circuit 47 generates a DC signal corresponding to the actual temperature of the object to be detected. Output. Then, a DC signal corresponding to the actual temperature outputted from the combining circuit 47 is led out from an output terminal 48 to a desired circuit.

In addition, each of the above-mentioned detectors 4 and 4s was slightly changed, and the fifth
Infrared detectors 49, 50 as shown in FIGS.
It's good as well. That is, in the infrared detector 49 in FIG. 5, a frame 51 integrally provided with first infrared non-passing bodies 25, 25, . . . is provided on the first infrared transmitting body 24 via spacers 52, 52. In the infrared detector 50 in FIG. 6, the second infrared transmitting body 26 is fixed to another fixing base (not shown) provided in the housing 12, and the frame 51 is attached to the bimorph 28. has been done.

(F) Effects of the Invention According to the infrared detection device of the present invention, an infrared detection body that generates an alternating current signal according to the amount of change in incident infrared radiation;
It has a plurality of linear infrared passing portions and infrared non-passing portions extending alternately in a direction perpendicular to the displacement direction, and is located in an area through which infrared rays from the detected object pass in order to be incident on the detected object. a pair of opposing bodies located;
A state in which the infrared passing parts and the infrared non-passing parts of the pair of opposing bodies substantially overlap each other, and the infrared passing part and the infrared passing part of one opposing body and the infrared passing part and the infrared passing part of the other opposing body. A vibrating body that vibrates to periodically repeat a state in which the two substantially overlap each other, a pulse signal generator that generates a periodic pulse signal for vibrating the vibrating body, and generation of the generator. A synchronous detector is provided for inputting the pulsed signal and synchronously detecting an alternating current signal from the infrared detector based on the signal, a chopper for changing the infrared rays incident on the infrared detector, Since a motor or the like is not required, the infrared detection device itself can be made smaller, and since the infrared rays incident on the infrared detection body change evenly and periodically, infrared detection can be performed with high precision. In addition, since the plurality of linear infrared passing parts and infrared non-passing parts are alternately extended in a direction orthogonal to the displacement direction,
The overlapping area of the infrared transmitting parts of the pair of opposing bodies is very large, and the amount of infrared rays incident on the infrared detecting body becomes very large, which increases the detection output from the infrared detecting body and improves detection accuracy. Also,
By alternately providing a plurality of infrared passing parts and infrared non-passing parts, even if the widths of the infrared passing parts and infrared non-passing parts are reduced in the displacement direction, the overlapping area of the infrared passing parts of both opposing bodies can be reduced. Therefore, by reducing the width in the displacement direction, the amount of displacement of the opposing body can be reduced. Thereby, the voltage applied to the vibrating body can be reduced, and the shape of the vibrating body can be made small. Furthermore, it is possible to perform synchronous detection of the alternating current signal from the infrared detector by also using a periodic pulse signal for vibrating the vibrating body. There is no need to separately provide a dedicated synchronous pulse generator for generating the synchronous pulse, thereby simplifying the infrared detection device.

[Brief explanation of the drawing]

Figures 1a and b are a side view and a plan view, respectively, of a conventional infrared detection mechanism, Figure 2 is a sectional view of an infrared detector of an infrared detector according to an embodiment of the present invention, and Figure 3 is another infrared detector of the same device. 4 is a circuit diagram of the same device shown in FIGS. 2 and 3, and FIGS. 5 and 6 are sectional views of other infrared detectors of the same device, respectively. 5... Infrared detector, 12... Storage body, 23...
...Opening, 24...First infrared passing body, 25, 25
s...First infrared non-passing body, 26,26s...Second infrared transmitting body, 27,27s...Second infrared passing body, 28 and 28s...Bimorph, 40...
...Pulse oscillator, 46...Synchronous detector.

Claims (1)

[Claims] 1 An infrared detector that generates an alternating current signal according to the amount of change in incident infrared rays, a plurality of linear infrared passing parts and infrared non-passing parts extending alternately in a direction perpendicular to the direction of displacement, and a A pair of opposing bodies located in a region through which infrared rays from a detection body pass in order to enter the detection body, a state in which the infrared passing portions and infrared non-passing portions of the pair of opposing bodies substantially overlap each other, and one opposing body A vibrating body that vibrates to periodically repeat a state in which an infrared passing part and an infrared passing part of a body and an infrared passing part and an infrared passing part of another opposing body substantially overlap, respectively. A pulse signal generator that generates a periodic pulse signal for vibration, inputting the pulse signal generated by the generator, and synchronously detecting the alternating current signal from the infrared detector based on the signal. An infrared detection device characterized by comprising a synchronous detector for.