JPS60128316A - Infrared sensor - Google Patents

Abstract

PURPOSE:To improve S/N and reliability by setting the surface electrode to a constant potential, and also applying a driving signal which becomes an AC with respect to the constant potential, to the center electrode. CONSTITUTION:Vibrating bodies 48, 49 are vibrated basing on a voltage applied to the third and the fourth terminals 22c, 22d. That is to say, a DC constant- voltage of about +5 volts is applied to the fourth terminal 22d so that each surface electrode 53a, 53b and 54a, 54b becomes a constant potential. On the other hand, voltages of about +35 and -25 volts are applied alternately and periodically to the third terminal 22c in order to apply a driving signal which becomes an AC with respect to the constant potential, to center electrodes 50a, 50b. As a result, a state that the center electrodes 50a, 50b become 30 volts higher than the surface electrode, and a state that the former becomes lower by 30 volts are repeated alternately. As a result, an infrared-ray detecting body varies periodically an incident infrared-ray quantity, and outputs a signal corresponding to a temperature difference of an object to be detected and opposed bodies 56, 57.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an infrared sensor number ζ for detecting the temperature of an object to be detected using infrared rays, for example.

(b) Prior Art In No. 11 and b, the recent infrared sensor (1) has a built-in infrared detector, for example, a pyroelectric type. Such an infrared detector has a characteristic of generating electric charge based on the amount of change in incident infrared light, and the detection accuracy of the infrared detector improves as the amount of incident infrared light changes more periodically. It is necessary to periodically change the infrared rays incident on the body, and for this purpose, a metal chopper (3) that is rotated periodically by a synchronous motor (2) is placed in front of the infrared sensor (1). ing. Therefore, such ChiB
- When the infrared rays from the object to be detected and the infrared rays from the tip 9 (3) are alternately and periodically incident on the infrared detecting body by rotating the V pass (3), the infrared detecting body detects the incident infrared rays. The amount changes periodically to generate a charge. Such charges are used to measure the temperature of the object to be detected.

However, in the above configuration, the motor (2) and the chip (3) have a fairly large shape, and there are problems in terms of space.

Therefore, an infrared sensor (4
) has come up with the idea. The infrared sensor (4) has external dimensions of 60 mm in length, 60 mm in width, and 20 mm in height, respectively.
It has a water-shaped rectangular parallelepiped shape with a length of 151 m, and has a built-in new chi9/ripa mechanism, which eliminates the need for the motor (2) and chishipa (3) as described above, solving the space problem. has been done.

The specific structure of the infrared sensor (4) will be explained below.

The interior of the sensor case (8), which consists of a metal lip (5) and a carrier lip (7) having an infrared transmitting part (6), is surrounded by a shield body (9) and is A pyroelectric type infrared detection system that generates an electric charge based on the detection object, and a beam/reverse mechanism that changes the infrared rays incident on the detection object are provided. The configuration consists of a pair of piezoelectric noodle moving bodies (i21) and a pair of opposing bodies (13, α-shaped) fixed to each end of the vibrating body.Such opposing bodies Q3 , (14) has a plurality of pick-up lenses of the same shape and size that allow infrared rays to pass through ■, α9...-
...is formed.

Therefore, between the above-mentioned vibrating bodies, (121 vibrates periodically in mutually opposite directions (A or B direction), and from this), the above two opposing bodies +1:l) and (14) have a periodic relative positional relationship. The above-mentioned opposing body (1, α-gradient slits 115+, (15)... overlap each other and almost completely open, and each slit) (151, α-gradient... The state in which the rainbows do not overlap and are almost completely occluded is periodically repeated.

Then, in the above superimposed state, the infrared rays from the object to be detected pass through the infrared transmitting part (6) of the case (8) and the slits (2) of both opposing bodies α3, (14), (to)...
On the other hand, in the non-overlapping state, only the infrared rays from the opposing bodies (13) and (14) enter the infrared detection system, so that the infrared detector αe enters the infrared detection body (1). The amount of infrared radiation changes periodically,
For example, a charge is generated for measuring the temperature of the object to be detected.

Now, the basic structures of the piezoelectric vibrators aυ and a2J are surface types J1i (11a), (11b) and (121
), (12b). Then, the vibrating body (1
1) is the surface type 1!i+(11
aX11b) A state is obtained in which the magnitude relationship of the potentials of the drive signal voltages to each is periodically reversed, so that the vibrating body αυ is A.

It bends and vibrates in the B direction. On the other hand, when the vibrating body 0 is turned on, an AC drive signal voltage is similarly applied to the surface electrode (12b), and in this case, the vibrating body 02! is opposite to the vibrating body α1 as described above. It is designed to bend and vibrate in the Is and A directions.

Here, the above surface electrodes (11s (11b) and (12a)
) (12b) is alternating current, so noise based on the alternating current component is generated on the surface electrode (12b).
11 aX11b) and (1, za This has the disadvantage of causing a decrease in the S/N ratio.

No. 3 OBJECT OF THE INVENTION An object of the present invention is to obtain a highly reliable infrared sensor that is not affected by noise based on an AC drive signal applied to a vibrating body and does not cause a decrease in the S/N ratio.

←) Structure of the Invention In order to achieve the above object, the infrared sensor of the present invention includes an infrared detector that generates an electric charge according to the amount of change in incident infrared radiation, and a plurality of infrared detectors located in the infrared incident area of the infrared detector. A pair of opposing bodies having a passing portion and an infrared ray non-passing portion are vibrated to periodically change the opening/closing degree of the infrared passing portion of the pair of opposing bodies. a vibrating body, the vibrating body comprising a central electrode, piezoelectric bodies disposed on both sides of the central electrode, and protruding surface electrodes disposed on each four outer surfaces of the piezoelectric body; It is characterized in that the vibrating body is made to vibrate by setting the surface electrode at a constant potential and applying a drive signal that is an alternating current with respect to the constant potential to the center electrode.

Embodiment #c4 to FIG. 12 are infrared sensor Q6 according to the embodiment of the present invention.
The structure of 1 is shown. The length, width, and height of this sensor αQ are 24 m and 16.15 m, respectively, and it is considerably miniaturized like the above-mentioned sensor (4).

First, the sensor case 0'I) consists of a metal cap and cover (19). The cap α (to) has an external infrared entrance port (211 is formed.Also, refer to the above for the first to fifth
The terminals (22a) to (22e) are implanted through an insulator, and the sixth terminal (22) is implanted directly.

Furthermore, the 7th and 8th terminals (22g) (22h
) have been planted.

Therefore, in the above case αη, an alumina main board with a length of 20 m, a width of 11 m, and a thickness of 11 gI, for example, is glued and placed on the above upwelling with an epoxy-based insulating adhesive. ing. In this case, the main board (2) is the first
-8th terminal holes (250 - (25h)), and the above-mentioned first - eighth terminals (22a) - (22h) are fitted into these terminal holes (251 - (25h), respectively. The first to seventh electrodes (261) to (26g
) is patterned by screen printing and sintering silver palladium. These 1st to 6th trains II
(26m) ~ (26f) 1cGi husband/r above jF1
~6th terminal (22~(22f)) is connected by solder.The above 6th terminal J! ing.

　′.

In the case αη, an infrared detector fin, a chip ellipse (support), etc. are arranged in a hybrid-like manner on the main substrate (c), thereby achieving compactness.

First, to explain the infrared detection section (a), it has front and back electrodes (support), C1), and is made of lithium tantalate (LiTa) that generates electric charge based on the amount of change in incident infrared rays.
gs) A pyroelectric infrared detector Cl1) made of a single crystal with a tuning angle of about 1.5 is provided, and conductive adhesive such as silver paste or t is placed on a metal support base made of phosphor bronze. It is fixed with adhesive. Then, the above-mentioned support stand (to) is also attached to the above-mentioned 6th electric conductor by using conductive adhesive (to) such as silver paste.
i! 1 (26f), and thereby the back type WA (30) is fixed to the wide part (26f) of the adhesive C (31, C1
41, is electrically connected to the sixth terminal (22f) via the support base (2) and the sixth terminal (26), while the surface terminal (2) is electrically connected to the seventh terminal (26g). is electrically connected to.

In addition, the above-mentioned infrared detector (31 as well as a resistor chip (T))
An isolated FET□□□ is provided. Such a resistor chip c35) is particularly constructed as shown in FIG. 11, and a piece of alumina is used, and a pair of resistors is formed by screen-printing silver-palladium on both ends of one side of the piece and ζ-sintering it. Type! li (, 58a) (38b) are formed, and a resistance layer of 1010 to 10''Ω is formed across the electrodes □□□
is formed by screen printing. Then, for the resistor chip F351, connect both the resistor electrodes (58 (38b) with cream solder to the sixth and seventh electrodes (26f) (26g).
) is fixed on the main substrate (2).

Historically, the yET@ is fixed on the main substrate (23) with the source S1 and the drain D.

The infrared detector Gυ, the resistor chip, and the FET t361 are covered with a metal shield (A) made of phosphor bronze or tin and whose inner surface is coated with black matte paint. The shield body has a triangular roof shape. Therefore, the above shield body (4 [is lower PjI (40s (40a)
) is engaged with the long side (25 (2311)) of the main board □□□, and the claws (40b) (40b) are formed in the main board (notch part (23b) and engagement hole (23C)) is soldered to the 1N6 electrode (26f) while being engaged with the shield body (26f), thereby fixing the shield body (2) on the inside of the main board and forming an external wire passage hole (41).

Next, to explain the above-mentioned part 3-w, there is an alumina fixing plate (@).The height, width, and thickness of the fixing plate are, for example, 1t1.10.2mm, respectively. and
The above-mentioned fixing panel has retaining pieces (43 pieces (43 pieces) at both ends of the lower part).
3b) is a notch (4) formed at the corner of the main board (to).
4 (44b), and then apply an epoxy-based insulating adhesive (
It is fixed with adhesive at 451. Also, the upper fixed plate (transfer)
For example, the length 41111. A pair of notches (46b) with a width of 0.5 wm were formed at a distance of 5 m from each other, and one side of the fixing plate (@) was screen printed with silver palladium in the same way as the main board. Two electric JMs (47a) (47b) are patterned by sintering with Now, these paintings 1i (47
a) (47b) are the third and fourth boards on the main board (2), respectively.
Electric! (26CX26d) is soldered connected.

In both of the notches (46a) and (46b), a pair of vibrating bodies +481. (49) is arranged perpendicular to the fixed plate (41), and the vibrating bodies (48), (491
is fixed with epoxy-based insulating adhesive. Upper M
d In the vibrating body decoy and vessel, as shown in detail in Fig. 6 and Fig. 1Q, a central electrode (50 s
ob) s, and piezoelectric materials (
51a) (51b) Knots (52s (52b)) are provided, and these piezoelectric bodies (51s (51b) and (52a) (s)
Surface molds 4 (53 (53b) and (54m) (54b)) made of silver or the like are formed on the outer surface of the piezoelectric body (51 (svb) and (52m)).
(52b) is the above vibration regime, the polarization (sixth
Figure polarization direction P). Then, the surface electrode (5
3a) (s3b) and (54a) (54b) are connected with cream solder to the electrode (47b) of the fixed plate (roller) above, and the center electrode (soa) (sob) c vibrator (48, (41) The branch piece is connected to the electric @ of the above fixed plate (roll).
(It is bent toward the 47 side, and the electrode is connected to the 47 side with cream solder.)

On the free end side of the vibrating body (ω, They are glued and fixed with SG210M (Sumiki Miso) so that they are in a hand-to-hand state.In this case, the above central type, [175
For example, the length of the adhesive part of 0a) (50b) is 2.7W1.
A depression (58b) with a depth of 0.17 is formed,
The acrylic insulating adhesive accumulates in this part, and the adhesive fixing strength of [ on the opposing body side] is sufficient between the opposing body [Co., Ltd.] and the vibrating body (48), ta. .

And, on both opposing body sides, @ is made of an infrared opaque material such as aluminum, as shown in FIG. As shown in detail in FIG. 1B, a plurality of fan-shaped linear extensions are formed on the infrared passing portion side, and between each of the passing portions, an infrared non-passing portion Iυ is formed.

(@ is located.These infrared passing parts (511),
+1Xll and the non-passing part Ill (6m) both have the same dimensions and the same shape.

On the main board in the case aη, the temperature inside the case αη, which is equal to the temperature of the infrared passing part fin and the tipper mechanism part ■, of the opposing bodies □□□, @ is measured. The temperature-measuring diode (E) is configured in a hybrid manner.The diode haze is placed in an upright state, and its anode and cathode are connected to the fifth and sixth electric currents Fi (26e) (26e) on the main board (2), respectively. 2sf).

Next, the specific operation of the sensor (161) will be explained.

The vibrating bodies (411t) and (4!51 vibrate based on the voltage applied to the third and fourth terminals (22C) (22d). That is, the fourth terminal (22d) has
Each of the above surface electrodes (53 (53b) and (54 (54)
b) A constant DC voltage of approximately +5 volts is applied to maintain a constant potential, while a voltage of approximately +5 volts is applied to the third terminal (22C) to drive the center electrode (50a) (sob) to an alternating current with respect to the constant potential. Approximately +35 and -2 to apply the signal.
A voltage of 5 volts is applied alternately and periodically (frequency 3-5 Hz). Then, the third and fourth terminals (22C) (
22d) on the fixed plate (roller) 11 (47s(4)
The vibrating bodies (48) and (a
center electrode (50 sob) and surface electrode (53 sob)
53b), central type fii (5oa) (sob)
nogataka table iii114 (ssa) (s3b) (54m)
(54b), a state in which the voltage is higher by 30 volts (hereinafter referred to as the H state) and a state in which the voltage is no longer lower by 30 volts (
(hereinafter referred to as "low state") are alternately repeated at a frequency of 3 to 5 Hz as shown in FIG. 14. Therefore, in the case of the H state, the vibrating body (a), (491 piezoelectric body (51
11) As the (52a) shrinks, the piezoelectric body (51b) (52
b) is extended, both vibrators 14gI, (a is S respectively).

Deflects in the S direction (Figure 6). On the other hand, in the above state, both vibrators (48+, (4(g)) are S
, deflects in the S direction. As a result, the vibrating body (481, t
The n pulls are periodically vibrated in opposite directions.

Then, based on such vibration, the above-mentioned opposing body (a).

The mark indicates a state in which the relative positional relationship is displaced, and both opposing bodies (to), the infrared passing portion of tn, and ■ are almost overlapped and open (
(corresponding to the above-mentioned H state) and a state in which they are occluded with almost no overlap (corresponding to the above-mentioned state) are periodically repeated. Then, the infrared detector G11l detects the infrared rays from the object passing through the external infrared entrance (21) and entering the sensor case η and the infrared rays from the opposing body side (support). The incident infrared light changes periodically, and therefore outputs a charge corresponding to the temperature of the object to be detected, more specifically, a signal corresponding to the temperature difference between the object to be detected and the opposing body side.

Such a signal is passed to the gate G of the FET0i9, and from the source S of the FET ([) to the first terminal (22a
) is output to the outside of the infrared sensor (16).

FIG. 13 shows a circuit including such a sensor α0.

The constant voltage of about +5 volts is applied to the fourth terminal (22d) from the constant voltage circuit (E), and the iJ3 terminal (22
C), the output from the oscillator is amplified via an amplifier circuit, and the above voltages of approximately +35 and -25 volts are alternately and periodically applied. This causes the vibrating body (marked 4, 14
! vibrates as described above, and during such vibration the first terminal (
22 outputs a signal corresponding to the temperature difference between the object to be detected and the opposing body. Such a signal actually forms an alternating current e as shown in FIG. 14, and its amplitude corresponds to the above-mentioned temperature difference. The signal from the first terminal (22a) is input to the synchronous detector (to) via the filter amplifier. Approximately 1 is connected to the input side of the above filter amplifier.
A resistor ffl of Ω is connected to 0. Such resistance ffυ
constitutes an impedance conversion circuit (2) together with the resistance (to) of the sensor αe and Fl''1@.

The detector side synchronizes the AC signal e with the output of the upper za oscillator (67), and when the temperature of the object to be detected is higher than the temperature of the opposing body ω), (5η), the temperature is A positive DC signal corresponding to the difference is detected and output, and if the temperature of the object to be detected is lower than the temperature of the object (5Efl, (57)), a negative DC signal corresponding to the temperature difference is detected and output. That is, As the above AC signal C, the temperature of the object to be detected is the temperature of the opposing object (!@
, if the temperature is higher than (57), the positive half cycle e0 coincides with the above H state, and the temperature of the detected object is in the opposite regime), @
When the temperature is lower than , the negative half cycle e- coincides with the above H state. When the former matches, the detector (2) outputs a positive DC signal corresponding to the temperature difference between the detected object and the opposing body (■), and when the latter matches, the temperature A negative DC signal corresponding to the difference is output.

Then, the output from the detector (2) is sent to the DC amplifier (2).
) is input into the synthesis circuit υ gold. The synthesis circuit further includes the output from the temperature-measuring diode can, that is, between the opposing bodies,
(A signal corresponding to the temperature of 5η is inputted via a DC amplifier (Co., Ltd.).The above-mentioned synthesis circuit adds these two inputs and outputs a signal corresponding to the actual temperature of the object to be detected. Such an output is led to an output terminal surface for outputting to a desired circuit via a DC amplifier.

Now, the third terminal (22c), the third electrode (26c) and the fixed plate (@ electrode (47) are connected to the vibrating body (other).

When the AC drive signal voltages (+35 volts and -25 volts) are applied to the center electrodes (5(1a) and 50b) of the wire as described above, noise based on the AC component is generated as described above at the center type @(50λ)( 50b). However, in this case, the central electrode (50b) is generated from the surface electric potentials (53S (53b) and H (s4a) (s4b) i
In such a configuration, from the central electrode (50a) (50b) to the surface electrode (
53a), (53b) and (54), and therefore, such noise is transmitted in the infrared rays passing direction within the shield body (transfer), and in the above structure, the opposite body side (support) is fixed. In this case, the central type is 1% (5
The opposing bodies that can radiate noise from the central electrode (50b) are insulated from the center electrode (50sob), and the noise shielding at this point is also sufficient.

In addition, the vibrating body (4) has third and fourth electrodes (26, C) (26d) to which a voltage is applied for vibrating the body, and a first electrode (26, C) (26d) for outputting a signal according to the temperature difference. 11i(2
6a), there is a grounded sixth electrode (26) crossing section (26f).Furthermore, there is a grounded sixth electrode (26f) between the fixed plate and the third and fourth electrodes (26C) and (26d). (41
The upper electric wire i (47a) (47b) and the above first electric wire 6 (26
In the space between the
There is a temperature-measuring diode haze with a series of cathodes. With such a configuration, together with the presence of the shield body (2), the first electrode (26a) etc. are connected to the third electrode (26a). 4th Electric Railway @(
2sc) (26d) and the electrode (47) of the fixed plate (roller)
It is thought that the electrostatic coupling with a) (47b) is significantly weakened, and as a result, the third terminal (22C) and the third terminal [1 (26C) to which the above-mentioned AC drive signal voltage is applied
) and the fixing plate (@ electrode (47). Even if noise similar to that described above occurs, the noise is significantly prevented from entering the shield body (a).

Here, the above infrared sensor αe and the conventional infrared sensor (
A comprehensive numerical comparison of 4) shows the results shown in the table below.

a radiation detector, and a device installed in the infrared incident area of the infrared detector,
a body including a plurality of infrared passing parts and a plurality of infrared non-passing parts;
The vibrating body is composed of a central electrode, piezoelectric bodies disposed on both sides of the central electrode, and surface charges disposed on the outer surfaces of each piezoelectric body, and the surface electrodes are kept at a constant potential. At the same time, the vibrating body is made to vibrate by applying a driving signal that is an alternating current to the constant potential to the central electrode, so that it is not affected by the alternating current driving signal applied to the vibrating body. The SN ratio is improved and a highly reliable infrared sensor can be obtained.

[Brief explanation of the drawing]

Figures 1a and b are a side view and top view of a conventional infrared detection mechanism, respectively; Figures 2 and s3 are a sectional view and a top view of the main parts of an improved conventional infrared sensor; Figure to 1st
2 shows the structure of an infrared sensor according to an embodiment of the present invention, FIG. 4 is an exploded perspective view, FIG. 5 is a sectional view seen from the side, FIG. 6 is a sectional view taken along the line ■-■ in FIG. The figure is a sectional view taken along the line ■-■ in FIG. 5, FIG. 8 is a sectional view taken along the line ■-■ in FIG. The figure is a bottom view of the resistor chip, FIGS. 12a and 12b are t-plane views of the opposing body, FIG. 13 is a circuit diagram including the infrared sensor of the above embodiment, and FIGS. FIG. 4 is a diagram of main signal waveforms in the figure. αη...Sensor case, α-cap, α (support)
・・・Here, (21) ・・・External infrared entrance, C
11ll...Infrared detector, (a...Shield body, (a-...Fixing plate, (50s(50b)...Central electrode, (51aX51b)(szsu(52b)...
Piezoelectric body, (53a) (53b) (54s (54b)-
...Surface electrode, decoy (Sakura...vibrating body, @( capital)...opposite body, @import...infrared passing section, @I)lB21-...
Infrared non-passage section.

Claims (1)

[Claims] (1) An infrared detector that generates a charge according to the amount of change in incident infrared radiation; a pair of opposing bodies that are located in the infrared incident area of the infrared detector and have a plurality of infrared passing parts and infrared non-passing parts; A vibrating body that vibrates to periodically change the opening/closing degree of the infrared passing portion of the pair of opposing bodies, the vibrating body being connected to a center electrode, a piezoelectric body disposed on both sides of the center electrode, and a surface electrode disposed on the outer surface of each of the piezoelectric bodies, by setting the surface electrode at a constant potential and applying a drive signal that is an alternating current with respect to the constant potential to the center electrode, An infrared sensor characterized by causing the vibrating body to vibrate.