JPH0334668Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an infrared detector for detecting the temperature of a detected part using infrared rays, for example.

(b) Prior Art In FIGS. 1a and 1b, a recent infrared detector 1 has a built-in infrared detector, for example, of a pyroelectric type. Such an infrared detector has a characteristic of generating electric charge based on the amount of change in the amount of incident infrared rays, and the detection accuracy of the infrared detector improves as the amount of incident infrared rays changes more periodically. It is necessary to periodically change the infrared rays incident on the detection object, and for this purpose, a metal chopper 3 is disposed in front of the infrared detector 1 and is driven to rotate periodically by a synchronous motor 2. This structure was created in 1973.
It is also shown in Publication No. 10467. Therefore, when the infrared rays from the detected part and the infrared rays from the chopper 3 are alternately and periodically incident on the infrared detecting body due to the rotation of the chopper 3, the amount of incident infrared rays is periodically incident on the infrared detecting body. and generates an electric charge. Such charges are used to measure the temperature of the detected part.

However, in the above configuration, the motor 2 and the chopper 3 have a considerably large shape, and there are problems in terms of space.

Therefore, an infrared detector 4 as shown in FIGS. 2 and 3 has been devised. Such an infrared detector 4
The external shape is a small rectangular parallelepiped, and a new chopper mechanism is built-in, thereby eliminating the need for the motor 2 and chopper 3 as described above, and solving the space problem.

The specific structure of the infrared detector 4 will be explained below.

Inside a case 8 consisting of a cap 7 having a metal header 5 and an infrared transmitting section 6, there is a pyroelectric infrared detector 10 which is surrounded by a shield body 9 and generates an electric charge based on the amount of change in incident infrared rays. A chopper mechanism is provided to change the infrared rays incident on the detection object. The chopper mechanism consists of a pair of piezoelectric vibrators 11 and 12 and a pair of opposing bodies 13 and 14 fixed to each end of the vibrators. Each of the opposing bodies 13 and 14 has a plurality of slits 1 of the same shape and size that allow infrared rays to pass through.
5, 15,... are formed.

Thus, a pulsed voltage is periodically applied to the piezoelectric vibrators 11 and 12, and in this case, one of the piezoelectric vibrators 11 is periodically applied only in the A direction each time the pulsed voltage is applied. Furthermore, the other piezoelectric vibrator 12 is periodically bent only in the B direction each time the pulsed voltage is applied. As a result, the relative positional relationship of the facing bodies 13, 14 changes periodically, and the slits 15, 15, . A state in which 15, 15, . . . do not overlap and are occluded is periodically repeated. Then, in the above-mentioned superimposed state, the infrared rays from the detected part are transmitted to the infrared transmitting part 6 of the case 8 and both opposing bodies 13,
14 slits 15, 15, . 10, the amount of incident infrared rays changes periodically and generates a charge for measuring the temperature of the detected part, for example.

However, in the infrared detector 4, the vibrators 11 and 12 have slits 15 and 1, respectively.
5, so that the state where they overlap and open and the state where they do not overlap and close are repeated periodically,
In this case, of course, the pulsed voltage periodically applied to each piezoelectric vibrator 11, 12 is required to have a large value.

Here, a large potential difference is successively generated in the piezoelectric vibrators 11 and 12 based on such a pulsed voltage between the electrodes, and in this case, the piezoelectric vibrators 11 and 12 have a drawback that deterioration progresses significantly. There is.

(c) Purpose of the invention The purpose of the invention is to significantly prevent deterioration of the piezoelectric vibrator and to obtain a highly reliable infrared detector.

(d) Structure of the invention In order to achieve the above object, the structure of the invention consists of an infrared detecting body that generates an electric charge according to the amount of change in incident infrared light, an infrared passing section and an infrared passing section arranged in the infrared incident area to the detecting body. a pair of opposing bodies that both have infrared ray non-passing parts, a central electrode, a pair of piezoelectric bodies having the same polarization direction and disposed on both sides of the central electrode, and disposed on the outer surface of each of the piezoelectric bodies. and a pair of vibrators that periodically change the opening/closing state of the infrared passing portion of each of the pair of opposing bodies.

The vibrators are arranged so that the polarization directions of their piezoelectric bodies are opposite to each other, and are brought into a non-vibrating state by keeping the central electrode at a constant potential and applying an alternating current voltage to the surface electrode. It is characterized by being periodically bent in both directions as a reference and vibrating in opposite directions.

(E) Embodiment FIG. 4 shows an infrared detector 16 according to an embodiment of the present invention. In the figure, numeral 17 is a pyroelectric infrared detector made of lithium tantalate (LiTaO ₃ ) single crystal and generates a charge as a temperature signal according to the amount of change in incident infrared rays, and 18 and 19 are the infrared detectors, respectively. Front and back electrodes are formed on the front and back surfaces with nichrome vapor deposited films, 20 is a metal support made of copper, phosphor bronze, etc., and the back electrode 1 is placed on the support.
The infrared detector 17 is fixed with a conductive adhesive 21 such as silver paste, with the infrared detector 9 facing the upper surface of the support base 20 .

Reference numeral 22 denotes a case consisting of a metal cap 23 and a header 24, and the support stand 20 is fixed on the header 24 inside the case. Reference numeral 25 denotes a ground terminal directly planted in the header 24, and this terminal is electrically connected to the back electrode 19 via the support base 20 and adhesive 21. Reference numeral 26 denotes a signal terminal implanted in the header 24 via an insulating material 27. The signal terminal is connected to the surface electrode 18 and is for extracting the electric charge generated in the detection body 17 to the outside. Reference numeral 28 denotes an opening formed in the cap 23 to allow infrared rays to enter the detection body 17 from the surface electrode 18 side;
Reference numeral 9 denotes an infrared transmitting body that closes the opening, and the transmitting body is made of a silicon or germanium plate with a thickness of several 100 μm and has a high transmittance for infrared rays having a wavelength of 2 to 15 μm.

Reference numerals 30 and 31 denote first and second planar opposed bodies arranged parallel to each other between the detection body 17 and the opening 28. Such first and second opposing bodies 30, 3
1, as shown in FIGS. 5a and 5b, are made of infrared opaque materials such as aluminum, gold, and silver, and extend in a fan-shaped line in a direction parallel to the plane of the paper (FIG. 4). 1 infrared non-passing portions 32, 32... and second infrared non-passing portions 33, 33... are formed, and between each of the first infrared non-passing portions 32, 32... and the second infrared non-passing portions 33, A slit-shaped first infrared passing section 3 is provided between each of the 33...
4, 34... and second infrared passing portions 35, 35... are formed. The non-passing parts 32, 32... and 33, 33... and the passing parts 34, 34... and 3
5, 35... have the same dimensions and shape, and have widths W1,
W2 is 100 μm and 120 μm, respectively.

Reference numeral 36 denotes a first vibration mechanism for vibrating the first opposing body 30, and a second vibration mechanism 37 for vibrating the second opposing body 31 is formed behind this mechanism (FIG. 4). There is.

FIG. 6 shows details of the first and second vibration mechanisms 36 and 37, and 38 and 39 are rectangular parallelepiped-shaped vibration mechanisms, and the first and second opposing bodies 30 and 31 are fixed to the right end, respectively. In the second vibrator, both the first and second vibrators are constructed as shown below. That is,
A conductor made of phosphor bronze, stainless steel, etc. serves as the central electrode 40, and on both sides of the electrode 40, polarized piezoelectric materials 41 made of barium titanate, lead zirconate titanate, etc. are arranged in the direction of polarization (arrow P). ) are the same (and are opposite for the first and second oscillators 38 and 39)
A surface electrode 42 made of silver or the like is formed on one surface of the piezoelectric body 41.

Reference numeral 43 denotes a conductive support base made of an elastic conductive material such as phosphor bronze, and placed on the header 24 via an insulator. , the first and second vibrators 3
Width W slightly smaller than the width of 8.39 (for example, 5 mm)
First and second grooves 44 and 45 are carved therein. The first and second vibrators 38 and 39 are press-fitted into the first and second grooves 44 and 45, respectively, so that the surface electrodes 42, 42, . . . and the support base 43 are electrically connected. It matches. Further, the center electrodes 40, 40 of the first and second vibrators 38, 39 are both bent inward and soldered to each other.

46 and 47 are insulating materials 4 attached to the header 24, respectively.
The center electrodes 40 and 40 of the first and second vibrators 38 and 39 are connected to the lead wire 50 at the first vibration terminal 46.
The support base 43 is connected to the second vibration terminal 47 by a lead wire 51.

Thus, a constant voltage of -20V is applied to the first vibration terminal 46, and a voltage of +20V is applied to the second vibration terminal 47.
Voltages of 10V and -50V are applied periodically in alternating current. That is, a constant voltage of -20V is applied to the center electrodes 40, 40 of the first and second vibrators 38, 39, and voltages of +10V and -50V are periodically applied to each surface electrode 42, 42, etc. be done. And then +
When a voltage of 10V is applied, the outer piezoelectric body 41 of the first vibrator 38 contracts and the inner piezoelectric body 41 expands, so that the first vibrator 38 bends in the direction of arrow A. Further, in the second vibrator 39, the inner piezoelectric body 41 expands and the outer piezoelectric body 41 contracts, so that the second vibrator 39 is bent in the direction of arrow B.

On the other hand, when a voltage of -50V is applied to the second vibration terminal 47, the first and second vibrators 38 and 39 bend in directions B and A, respectively, contrary to the above description.

As a result, the first and second vibrators 38, 39
vibrate periodically in opposite directions, and based on such vibrations, the first infrared passing section 3 of the first opposing body 30
4, 34... and first infrared non-passing parts 32, 32...
and the second infrared non-passing portions 33, 3 of the second opposing body 31.
3... and the second infrared passing sections 35, 35... overlap each other, and the infrared passing sections 34, 34..., 3
5, 35... and infrared ray non-passing parts 3
The state in which 2, 32..., 33, 33... are superimposed is
repeated alternately, i.e. each infrared passing section 34,
The opening/closing states of 34... and 35, 35... change periodically, and infrared rays from the outside that have passed through the transmitting body 29 intermittently enter the detection body 17. changes, and generates a charge for measuring the temperature of the detected part, for example.

Here, both the first and second vibrators 38 and 39 are periodically bent in directions A and B based on the non-vibration state shown in FIG.
0, 31 infrared passing portions 34, 34, ... and 3
Reliable periodic opening and closing of 5, 35, etc. can be obtained.
In this case, the first and second vibrators 38 and 39 are A,
The sum of the small amounts of deflection in each direction B matches the large amount of deflection when periodically deflecting only in direction A or B to obtain the same open/closed state as in the past. . In this case, each piezoelectric body 4 in the first and second vibrators 38 and 39
The potential difference generated between the electrodes 1, 41, . . This results in
Deterioration of the piezoelectric bodies 41, 41, . . . can be significantly prevented.

(f) Effects of the invention According to the invention, a vibration made of a piezoelectric material is used to periodically change the opening/closing state of each infrared passing section of a pair of opposing bodies in order to change the amount of infrared rays incident on the infrared detector. In the vibrator, it is only necessary to create a small potential difference between the electrodes, and therefore deterioration of the vibrator can be significantly prevented, and an extremely reliable infrared detector can be obtained.

[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 improved conventional infrared detector, and Figure 3 is a plan view of the main parts of the same detector. 4 to 7 show an infrared detector according to an embodiment of the present invention, FIG. 4 is a sectional view, FIGS. 5a and 5b are plan views of the first and second opposing bodies, respectively, and FIG. 6 is a main part. The plan view, FIG. 7, is a front view of the conductive support base. 17... Infrared detection body, 30... First opposing body,
32...First infrared passing section, 34...First infrared passing section, 31...Second opposing body, 33...Second infrared passing section, 35...Second infrared passing section, 38
...First vibrator, 39...Second vibrator, 41...
Piezoelectric body.

Claims (1)

[Scope of Utility Model Registration Claim] An infrared detector that generates a charge depending on the amount of change in incident infrared rays, and a pair of opposing bodies that are disposed in the infrared incident area of the detector and have both an infrared passing part and an infrared non-passing part. and a center electrode, a pair of piezoelectric bodies having the same polarization direction and disposed on both sides of the center electrode, and a surface electrode disposed on the outer surface of each of the piezoelectric bodies, the pair of opposing a pair of vibrators that periodically change the open/close state of each infrared passing portion of the body, the vibrators are arranged such that the polarization directions of their piezoelectric bodies are opposite to each other, and An infrared detector characterized in that by setting the electrode at a constant potential and applying an alternating current voltage to the surface electrode, the infrared detector is periodically bent in both directions based on a non-vibrating state and vibrates in opposite directions.