JPH0678829U - Multi-element pyroelectric detector - Google Patents

Abstract

(57) [Summary] [Purpose] Along with being able to obtain a structure suitable for mass production, it is possible to respond relatively freely even if the shape of the element, preamplifier, number of output pins, etc. are changed, making it possible to realize multiple elements and multiple functions. To provide a multi-element type pyroelectric detector which can be relatively easily handled. [Structure] A substrate 5 having an opening 7 communicating between both surfaces 5a and 5b, and a pyroelectric element 3 and a plurality of optical filters 1 mounted to face the opening 7 on the respective surfaces 5a and 5b sandwiching this substrate. A preamplifier component 4 of each light receiving portion G mounted on the pyroelectric element side 5a of the substrate 5, a metal cap 6 covering the pyroelectric element 3 and the preamplifier component 4 on the pyroelectric element side 5a,
A filter holder that has an attachment portion 8 for each optical filter 1 and is fixed to the optical filter side 5b of the substrate 5 so that infrared light passing through each optical filter 1 can be received by each of the opposed light receiving portions G. It consists of 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-element pyroelectric detector capable of simultaneously measuring a plurality of gas species (multi-component gases) in a measurement gas, and more specifically, characteristic absorption according to the type and concentration of the measurement gas in a gas analysis cell. The present invention relates to a multi-element type pyroelectric detector in which a plurality of light receiving portions for receiving received infrared light are integrated on one pyroelectric element.

[0002]

[Prior art]

A general structure of the structure of the pyroelectric detector is shown in FIG. That is, the pyroelectric element 31 is mounted on the substrate 32 on which the components forming the preamplifier are mounted, and the substrate 32 is fixed on the metal stem 33 to seal external noise. Further, it is general that the structure is sealed by a metal cap 34 having an opening 34a for mounting an optical filter for receiving infrared rays. An optical filter 35 is attached to the opening 34a. In such a pyroelectric detector, the components mounted inside are limited by the size of the metal cap 34 and the number of output pins. Usually, the output pins, the power supply (V _cc), the three terminals of the earth (E), the output (V _s). However, the light receiving part formed in the pyroelectric element 31 is made to have multiple elements (dual twin structure, etc.), or has multiple functions (a sensor for temperature compensation of the pyroelectric element is built in, and a light source for sensitivity check is built in. In order to realize it on an extension of the structure of the pyroelectric detector, the space required for component mounting and the number of output pins are different, so the package (metal stem or metal As the number of types of caps increases, it is difficult to standardize parts, and when performing small-lot production, it is necessary to replace the jigs for production, etc., which tends to cause obstacles in mass production. I met

FIG. 13 shows a multi-element type pyroelectric detector in the case where the above pyroelectric type detector structure has multiple elements. In FIG. 13, the multi-element type pyroelectric detector has four light receiving parts and outputs them independently, so they are connected in dual quad, and the output pins are connected to the four outputs of the power source (V _cc ) and the ground ( A total of 6 are required including E). That is, each of the pyroelectric elements 21 is mounted on the substrate 23 on which the components forming the preamplifier 22 such as a J-FET or a chip resistor are mounted, and a pair of pyroelectric elements 21 is provided on one surface of each pyroelectric element 21. In addition to having the light receiving electrodes 24a and 24b, one common electrode (not shown) corresponding to the light receiving electrodes 24a and 24b is provided on the other surface. Further, the base plate 23 is fixed on the metal stem 25 in order to seal external noise. Furthermore, a structure generally sealed by a metal cap having an optical filter attachment opening 26 for receiving infrared rays is used. An optical filter (not shown) is attached to the opening 26. Also, when infrared light passing through the optical filter is incident on each of the four light-receiving part electrodes, crosstalk between the light-receiving parts is taken into consideration so that they do not leak to other light-receiving parts. 27 are provided.

[0004]

[Problems to be solved by the device]

 In this case, it is necessary to incorporate a preamplifier 22 for each output, and this preamplifier cannot be stored in a specified package, and it is necessary to use a package larger than that. In this way, when using multiple elements, if the package and the number of output pins differ depending on the specifications of the detector used, there are obstacles to mass production, such as the conventional production line cannot be used as it is. A suitable structure was desired. The same problem occurs not only in the case of using multiple elements but also in the case of using multiple functions.

The present invention has been made in view of such circumstances, and it is possible to obtain a structure suitable for mass production, and it is relatively free even if the shape of the element, the additional circuit (preamplifier, etc.), the number of output pins, etc. are changed. It is an object of the present invention to provide a multi-element type pyroelectric detector that can deal with the above requirements and can relatively easily cope with the increase in the number of elements and the combination of functions.

[0006]

[Means for Solving the Problems]

 This device is a multi-element device in which a plurality of light receiving parts for receiving infrared light that has received characteristic absorption according to the type and concentration of the measurement gas in a gas analysis cell are integrated on one pyroelectric element. In a type pyroelectric detector, a substrate having an opening communicating with both surfaces, a pyroelectric element and a plurality of optical filters mounted on the respective surfaces with the substrate sandwiched therebetween, and a plurality of optical filters, and It has a preamplifier component for each of the light receiving parts mounted on the pyroelectric element side, a metal cap for covering at least the pyroelectric element and the preamplifier component on the pyroelectric element side, and a mounting portion for each optical filter. A multi-element pyroelectric detector provided with a filter holder that is fixed to the optical filter side of the substrate, and that allows infrared light passing through each optical filter to be received by each of the facing light receiving sections. is there.

As the filter holder in the present invention, there may be mentioned a filter holder having a mounting portion composed of a window frame as many as the number of optical filters.

As a substrate in this invention, a conductor pattern for grounding which is connected to the ground except a part is provided on the surface on the optical filter side, while only the contact portion with the metal cap on the pyroelectric element side is provided. In addition to having a grounding conductor pattern, it is preferable to have a conductive pattern of a power source and a signal line in a portion which is not in contact with the metal cap. This grounding conductor pattern is, for example, a thick-film conductor layer for electromagnetic shielding made of copper foil having a thickness of about 0.1 to 0.3 mm, and is used for electromagnetically shielding the optical filter side of the substrate. On the pyroelectric element side of the board, especially the high impedance part is susceptible to external noise, so the entire pyroelectric element and preamplifier parts are covered with a metal cap. The grounding conductor pattern is also formed on the substrate contacting portion that comes into contact with the substrate.

In this invention, the optical filter is fixed to the mounting portion of the filter holder with an elastic adhesive such as a silicon-based material, and the filter holder is soldered or epoxy-bonded on the ground conductor pattern of the board. It is preferably fixed to the substrate via the agent.

Further, in this invention, it is preferable that the metal cap is fixed onto the grounding conductor pattern of the substrate via a solder layer or a conductive adhesive.

Further, in the present invention, the pyroelectric element is mounted on the board through the conductive pattern or conductive adhesive on the conductive pattern of the board, and the preamplifier component is provided around the conductive pattern on the conductive pattern of the board. It is preferable that it be mounted on the board via a conductive adhesive or a conductive adhesive.

In this invention, the conductor pattern formed on the substrate can be used as a terminal, which contributes to downsizing. That is, the output terminal of the light receiving portion may be formed as a conductor pattern on a partial end surface of the substrate on the optical filter side. For example, taking a multi-element type pyroelectric detector that outputs four sets of pyroelectric outputs by impedance conversion through respective preamplifiers, in the case of this four-element type, a power supply terminal (V _DD ) and a ground terminal (E), output terminals (V _s1 , V _s2 , V _s3 , V _s4 ) are provided, and the total number of external connections is 6 pins. Of course, 6 pins may be provided on the board, or a connector may be connected.

In this invention, a temperature compensation sensor for the pyroelectric element, a resistor for sensitivity check, and the like can be arranged on the substrate, and circuits in the subsequent stage such as an amplifier circuit and a judgment circuit can be arranged on the pyroelectric element side of the substrate. .

[0014]

[Action]

 In the conventional structure, even when trying to realize multiple elements, if the number of light receiving parts is multiple, the number of output pins, the size of the board, and the structure are restricted according to the number. In the invention, since the pyroelectric element and the plurality of optical filters are mounted on the respective surfaces of the substrate so as to face the opening, the tolerance at that point can be increased. Further, instead of directly bonding each optical filter to the substrate, after bonding or bonding a plurality of optical filters to the filter holder that fixes them once and then fixing the filter holder to the substrate, (1) When a deformation such as a peaking stress or mechanical deflection due to a difference in coefficient of thermal expansion occurs, a filter holder is placed between the substrate and the optical filter, so multiple optical filters are directly bonded or bonded to the substrate. The adhesive strength and airtightness can be maintained stronger than in the case of (2) multiple optical filters can be easily fixed, and the optical filter and filter holder can be made of elastic adhesive such as silicon The adhesive between the filter holder and the substrate can be selected by soldering or epoxy adhesive, etc., depending on the required adhesive strength. That. Further, (3) a temperature compensation sensor for a pyroelectric element, a resistor for sensitivity check, etc. can be incorporated in the substrate, and a circuit in the subsequent stage such as an amplifier circuit can be added to the substrate. In other words, when integrating a temperature compensation sensor, a resistor for sensitivity check, and a circuit in the subsequent stage on the board, it is less subject to package and structural restrictions, and only the number of parts to be mounted on the board can be increased. Therefore, the burden of assembling is small, and it is possible to correspond to the production of a relatively small lot.

[0015]

【Example】

An embodiment of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited thereby. 1 to 7 show a first embodiment of the present invention. 1 to 3, a multi-element pyroelectric detector is used in a gas analysis cell for three gas species of HC (hydro carbon), CO (carbon monoxide), and CO ₂ (carbon dioxide). The four light-receiving parts that receive the infrared light that has been absorbed by the characteristics according to the type and concentration of the measured gas including the reference gas type are integrated on one pyroelectric element. Four optical filters 1, 1, 1, 1, a filter holder 2 for fixing these optical filters, a pyroelectric element 3, and a preamplifier 4 for a pyroelectric element that needs a shield located near the pyroelectric element 3 The main components are a board 5 on which the and are mounted, a metal cap 6 for shielding noise from the outside, and the like.

That is, the multi-element type pyroelectric detector is mounted with a substrate 5 having an opening 7 communicating both surfaces 5a and 5b and a surface 5a, 5b sandwiching this substrate facing the opening 7. Pyroelectric element 3 and a plurality of optical filters 1, 1, 1, 1, the preamplifier component 4 of each light receiving portion G mounted on the pyroelectric element side 5a of the substrate 5, and the pyroelectric element on the pyroelectric element side 5a. 3 and the preamplifier component 4 and the metal cap 6 and the mounting portion 8 for each optical filter 1 are fixed to the optical filter side 5b of the substrate 5, whereby infrared light passing through each optical filter 1 is blocked. It is mainly composed of a filter holder 2 capable of receiving light from each of the opposed light receiving sections G.

Further, the filter holder 2 is formed to have as many mounting portions 8 as the window frame 8 a as the number of the optical filters 1.

The substrate 5 has a grounding conductor pattern (inner region surrounded by diagonal lines in FIGS. 1 and 2) P connected to the ground except for a part 5c on the surface of the optical filter side 5b. The conductor pattern P for grounding is provided only on the contact portion of the pyroelectric element side 5a with the metal cap 6, and the conductive pattern D (see FIG. 3) of the power source and the signal line is provided on the non-contact portion with the metal cap 6. Have.

The ground conductor pattern P is, for example, a thick film conductor layer for electromagnetic shielding made of copper foil having a thickness of about 0.1 to 0.3 mm, and serves to electromagnetically shield the optical filter side 5b of the substrate 5. In addition, on the pyroelectric element side 5a of the substrate, especially the high impedance portion is easily affected by external noise, so the pyroelectric element 3 and the preamplifier component requiring the shield ( Since the entire structure (disposed on the other part of the substrate) 4 is covered with the metal cap 6, the grounding conductor pattern P is also formed on the part of the substrate contacting the metal cap 6.

In FIG. 3, the optical filter 1 is fixed to the mounting portion 8 of the filter holder 2 with an elastic adhesive 10 such as silicon, and the filter holder 2 is soldered on the earth conductor pattern P of the substrate 5. It is fixed to the substrate 5 via a layer (or an epoxy adhesive) 11.

Further, in FIG. 3, the metal cap 6 is fixed onto the grounding conductor pattern P of the substrate 5 via a solder layer (or a conductive adhesive) 12.

Further, in FIG. 3, the pyroelectric element 3 is mounted on the substrate 5 via the conductive paste or the conductive adhesive 12 a on the conductor pattern D of the substrate 5, and the preamplifier component 4 is also provided on the periphery thereof. 5 is mounted on the substrate 5 via a conductive paste or a conductive adhesive on the conductor pattern D.

Further, the six conductor patterns (see FIGS. 2 and 7) 13 formed on the substrate 5 can be used as terminals, which contributes to miniaturization. At this time, taking a multi-element type pyroelectric detector that outputs four sets of pyroelectric outputs through impedance conversion through respective preamplifiers, in the case of this four-element type, the terminal 13 is a power supply terminal ( V _DD ), a ground terminal (E), and output terminals (V _s1 , V _s2 , V _s3 , V _s4 ) (see FIG. 8). In FIG. 8, reference numerals C ₁ and C ₂ are capacitances between the light receiving electrode and the common electrode of the light receiving portion G, which are generated by the pyroelectric element 3, and reference numerals T and R _G form the preamplifier 4. These are the J-FET and the chip resistor, which are the components.

Since this embodiment has the above-mentioned configuration, the pyroelectric element 3 is placed on the one surface 5a of the substrate 5, and the optical filter 1 is placed at the corresponding position with the substrate 5 sandwiched therebetween. Has been implemented. At this time, the optical filter 1 is not directly bonded to the substrate 5, but the optical filter 1 is once bonded or bonded to the filter holder 2 for fixing them, and then the filter holder 2 is fixed to the substrate 5. Higher adhesive strength and airtightness can be obtained compared to the case where the optical filter is directly adhered to the substrate.

That is, when the substrate 5 is deformed due to a difference in coefficient of thermal expansion such as shear stress or mechanical deflection, the filter holder 2 is interposed between the substrate 5 and the optical filter 1, and therefore the optical Since the filter is not affected by the deformation of the substrate 5 more than when the filter is directly bonded or joined to the substrate, the fixing is stronger and the adhesive strength and airtightness can be maintained.

Further, the optical filter 1 and the filter holder 2 for fixing them are fixed with an elastic adhesive 10 such as a silicon-based material, and solder 11 is attached between the filter holder 2 and the substrate 5, or The adhesion method can be selected by focusing on the adhesion strength such as epoxy adhesive.

Further, by the window frame 8a of the filter holder 2, when the infrared light passing through the optical filter 1 enters each of the four light receiving portions G, the light receiving portions G 1, G 2 are prevented from leaking to the other light receiving portions G 1. , G, G can be prevented from crosstalk.

FIG. 9 shows a second embodiment of the present invention in which a component 18 such as a temperature compensation sensor for the pyroelectric element 3 and a resistor for sensitivity checking is arranged on the substrate 5 in the extension region M on the optical filter side 5b of the substrate. An example of is shown. At this time, the conductor pattern 13a of the terminal can be formed in the extension region M as in the first embodiment, and the ground conductor pattern P is not required in the extension region M.

FIG. 10 shows a multi-element pyroelectric detector in which a 16-element array S is formed, in which a circuit 19 in the subsequent stage such as an amplification circuit and a determination circuit is arranged on the pyroelectric element side 5 a of the substrate 5. A third embodiment will be described. The circuit 19 in the latter stage is mounted outside the metal cap 6. A conductor pattern 13b of a terminal is formed on the optical filter side 5b of the substrate 5.

Further, FIG. 11 is a schematic view of the multi-element type pyroelectric detector of the first and second embodiments, in which a circuit 19 at a subsequent stage such as an amplifying circuit and a judging circuit is arranged on the pyroelectric element side 5a. The fourth practical example of is shown. The circuit 19 in the latter stage is mounted outside the metal cap 6.

As described above, in each of the second to fourth embodiments, the component 18 such as the temperature compensating sensor of the pyroelectric element 3 and the sensitivity checking resistor is built in the optical filter side 5b on one surface of the substrate 5. When a circuit 19 in the subsequent stage such as an amplifier circuit can be added to the substrate 5 on the pyroelectric element side 5a on the other surface of the substrate 5, and the component 18 and the circuit 19 in the subsequent stage are integrated with the substrate 5, the package or Since the structure is unlikely to be restricted and it can be dealt with only by increasing the number of parts to be mounted on the substrate 5, the burden of assembling is small and it is possible to cope with the production of a relatively small lot.

[0032]

[Effect of device]

 As described above, the present invention has the following advantages as compared with the conventional structure in which the substrate is provided on the metal stem. 1. Even if the number of elements is increased, a structure suitable for mass production can be obtained. 2. Higher adhesive strength and airtightness can be obtained compared to the case where the optical filter is directly adhered to the printed circuit board. When a plurality of optical filters are used, it is advantageous that the high adhesive strength can be easily maintained. 3. It is possible to deal with multiple elements and multiple functions relatively easily. Even if the element shape, additional circuit (preamplifier, etc.), the number of output pins, etc. are changed, it is possible to respond relatively freely. 4. The circuits in the subsequent stages can be integrally mounted on the same printed circuit board. Since the amplifier circuit, temperature compensation sensor for the pyroelectric element, and resistor for sensitivity check can be freely arranged, a structure relatively strong against external noise and drift can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is an overall perspective view of the above embodiment.

FIG. 3 is an explanatory diagram of a main part configuration in the embodiment.

FIG. 4 is a simplified top view of the above embodiment.

FIG. 5 is a simplified side view of the above embodiment.

FIG. 6 is a simplified cross-sectional view of the above embodiment.

FIG. 7 is a simplified bottom view of the above embodiment.

FIG. 8 is an equivalent circuit diagram in the above embodiment.

FIG. 9 is an overall perspective view showing a second embodiment of the present invention.

FIG. 10 is an overall perspective view showing a third embodiment of the present invention.

FIG. 11 is an explanatory view of the overall configuration showing a fourth embodiment of the present invention.

FIG. 12 is an overall configuration explanatory view showing a conventional general pyroelectric detector.

FIG. 13 is a structural explanatory view showing a conventional multi-element type pyroelectric detector in the case of using multiple elements.

[Explanation of symbols]

1 ... Optical filter, 2 ... Filter holder, 3 ... Pyroelectric element, 4 ... Preamplifier, 5 ... Board, 5a ... Pyroelectric element side of board, 5b ... Optical filter side of board, 6 ... Metal cap,
7 ... Opening hole, 8 ... Optical filter mounting part.

Claims (10)

[Scope of utility model registration request] 1. A multi-element in which a plurality of light receiving portions for receiving infrared light which has been absorbed characteristically according to the type and concentration of a measurement gas in a gas analysis cell are integrated on one pyroelectric element. In a type pyroelectric detector, a substrate having an opening communicating with both surfaces, a pyroelectric element and a plurality of optical filters mounted on the respective surfaces sandwiching the substrate facing the opening, and a focus of the substrate. A preamplifier component of each of the light receiving portions mounted on the electric element side, a metal cap that covers at least the pyroelectric element and the preamplifier component on the pyroelectric element side, and a mounting portion of each optical filter of the substrate. A multi-element pyroelectric detector provided with a filter holder which is fixed to the optical filter side and thereby allows infrared light passing through each optical filter to be received by each of the opposed light receiving portions. 2. The multi-element type pyroelectric detector according to claim 1, wherein the filter holder is provided with as many mounting portions as window frames as the number of optical filters. 3. The substrate has a conductor pattern for grounding, which is connected to the ground except a part on the surface on the optical filter side, and at the same time, grounds only the contact portion with the metal cap on the pyroelectric element side. The multi-element pyroelectric detector according to claim 1, wherein the pyroelectric detector has a conductor pattern and also has a conductive pattern of a power supply and a signal line in a portion that does not contact the metal cap. 4. The optical filter is fixed to the mounting portion of the filter holder with an elastic adhesive such as a silicon-based adhesive, and the filter holder is soldered on the grounding conductor pattern of the substrate via a solder layer or an epoxy adhesive. The multi-element pyroelectric detector according to any one of claims 1 to 3, which is fixed to a substrate. 5. The multi-element type pyroelectric detection according to claim 1, wherein the metal cap is fixed on the grounding conductor pattern of the substrate via a solder layer or a conductive adhesive. vessel. 6. The pyroelectric element is mounted on a substrate via a conductive paste or a conductive adhesive on a conductive pattern of the substrate, and a preamplifier component is provided around the conductive pattern or a conductive adhesive on the conductive pattern of the substrate. The multi-element type pyroelectric detector according to claim 1, which is mounted on a substrate via the. 7. The grounding conductor pattern has a thickness of 0.1 to 10.
The multi-element pyroelectric detector according to claim 3, which is a thick-film conductor layer for electromagnetic shield made of a copper foil of about 0.3 mm. 8. The multi-element pyroelectric detector according to claim 1, wherein the output terminal of the light receiving portion is formed as a conductor pattern on a partial end surface of the substrate on the optical filter side. 9. The multi-element pyroelectric detector according to claim 1, wherein the substrate is provided with a sensor for temperature compensation of the pyroelectric element, a resistor for sensitivity check, and the like. 10. The multi-element type pyroelectric detector according to claim 1, wherein the substrate is provided with circuits at the subsequent stage such as an amplifier circuit and a determination circuit arranged on the pyroelectric element side.