WO2013099799A1

WO2013099799A1 - Infrared detector

Info

Publication number: WO2013099799A1
Application number: PCT/JP2012/083249
Authority: WO
Inventors: 角　貞幸
Original assignee: パナソニック株式会社
Priority date: 2011-12-28
Filing date: 2012-12-21
Publication date: 2013-07-04
Also published as: JP2013137259A; TW201337222A

Abstract

This infrared detector includes: a detecting body, which is configured of at least one pyroelectric element, and which is provided with first and second detecting sections that are configured to respectively generate first and second signals; a circuit block, which is provided with first and second amplifying sections that are configured to respectively amplify the first and second signals; a housing, which has a window hole, and which houses the detecting body and the circuit block; and an optical filter, which is provided in the window hole, and which is configured to transmit infrared. The optical filter has first and second transmitting regions at respective positions that correspond to the first and second detecting sections. The optical filter is configured such that infrared transmitting characteristics of the first transmitting region are different from those of the second transmitting region.

Description

Infrared detector

The present invention relates to an infrared detector that includes a pyroelectric element and is configured to detect a change in the amount of infrared rays.

Conventionally, a pyroelectric element is generally used as an element for detecting a change in the amount of infrared rays for the purpose of detecting a human body, for example. Infrared detectors using pyroelectric elements are used for automatic control of loads such as lighting in addition to intrusion detectors for crime prevention.

For example, Japanese Patent No. 3211074 (hereinafter referred to as “Document 1”) has a metal base part (base part) covered with a metal cap part (cap cover) inside a metal case (package). An infrared detector having a structure containing a pyroelectric element and a signal processing circuit is disclosed. In this detector, an optical filter that transmits infrared rays (infrared filter) is provided on the upper surface of the cap portion, and the infrared rays that have passed through the optical filter enter the detection portion of the pyroelectric element.

Furthermore, the infrared detector described in Document 1 is composed of a combination of a bandpass amplifier and a window comparator in the signal processing circuit. Thereby, the infrared detector converts the output of the pyroelectric element into a voltage, takes out a signal of a predetermined frequency by a bandpass amplifier, and outputs an H, L level signal from a window comparator in which a threshold value is set in advance.

Japanese utility model registration number 3133907 (hereinafter referred to as “Document 2”) includes a plurality of pyroelectric elements (pyroelectric infrared detection elements) and a signal processing circuit (detection circuit) in the same casing (package). An infrared detector having the above configuration is disclosed. In this infrared detector, independent signal processing circuits are connected to the electrodes of a plurality of pyroelectric elements, and an independent signal is output for each pyroelectric element. Thereby, an infrared detector becomes a structure from which the isolation | separation independent infrared detection area | region and detection angle are obtained.

By the way, if the infrared detector can simultaneously detect infrared rays in different wavelength ranges and output each detection result independently, the output can be used to identify, for example, the type of detection target or remove noise. It is done. In other words, if the distribution of the infrared fluctuation amount for each wavelength range is known, it is possible to identify the type of the detection target from this distribution, and from the difference in the infrared fluctuation amount in different wavelength ranges, from the detection target such as a human body. It is considered possible to detect noise components such as environmental temperature.

However, in the configuration of Document 1, since only one output can be obtained from one pyroelectric element, it is impossible to simultaneously detect infrared rays in different wavelength ranges and output the detection results independently. Further, even in the configuration of Reference 2, since the infrared detection area is spatially separated for each pyroelectric element by using a plurality of pyroelectric elements and a plurality of signal processing circuits, different wavelengths are used. It is not possible to detect the infrared rays in the region simultaneously and output each detection result independently.

The present invention has been made in view of the above-described reasons, and an object thereof is to provide an infrared detector capable of simultaneously detecting infrared rays in different wavelength ranges and independently outputting each detection result.

The infrared detector of the present invention includes a detector (3), a circuit block (5), a housing (2), and an optical filter (7). The detection body (3) includes at least one pyroelectric element (300) and includes first and second detection units (31 and 32) configured to generate first and second signals, respectively. The circuit block (5) includes first and second amplification units configured to amplify the first and second signals, respectively. A housing | casing (2) has a window hole (222), and accommodates the said detection body (3) and the said circuit block (5). The optical filter (7) is provided in the window hole (222) and is configured to transmit infrared rays. The optical filter (7) includes first and second transmission regions (71 and 72) at positions corresponding to the first and second detection units (31 and 32), respectively. The optical filter (7) is configured so that the infrared transmission characteristics of the first transmission region (71) are different from those of the second transmission region (72).

In one embodiment, the circuit block (5) comprises a signal processing circuit configured to process a signal from the detector (3). The casing (2) includes a base part (21) through which a terminal pin (6) electrically connected to the circuit block (5) is inserted, and a metal casing together with the base part (21). The cap part to comprise is provided. The window hole (222) is an opening provided in a part of the cap part (22). The detection body (3) is supported by the circuit block (5) at a position facing the optical filter (7) in the housing (2). The first and second detectors (31 and 32) are arranged at different positions in a plane along the optical filter (7).

In one embodiment, the area of the first transmission region (71) is different from that of the second transmission region (72).

In one embodiment, the infrared detector is disposed in a space between the detection body (3) and the optical filter (7) in the housing (2), and the space is disposed in the first detection unit ( 31) and a partition (8) for partitioning between the second detector (32).

In one embodiment, the partition (8) has a surface on which a reflective surface for reflecting infrared rays is formed.

In one embodiment, the detection body (3) includes first and second pyroelectric elements (300a and 300b) constituting the first and second detection units (31 and 32), respectively.

In one embodiment, the pyroelectric element (300) has a rectangular plate shape and is fixed to the circuit block (5) by at least four fixing points (302). Each of the at least four fixed points (302) is located on a pair of opposite sides on the surface of the pyroelectric element (300).

In one embodiment, the circuit block (5) includes a substrate (51) having a first surface facing the window hole (222) and a second surface facing the base portion (21). The detector (3) is attached to the first surface of the substrate (51), while the electronic components constituting the signal processing circuit (41, 42) are disposed on the second surface of the substrate (51). It is attached.

In one embodiment, the detector (3) includes the pyroelectric element (300) and first and second electrode portions (302a and 302b) connected to both ends of the pyroelectric element (300), respectively. Become. The pyroelectric element (300) and the first electrode part (302a) constitute the first detection part (31), while the pyroelectric element (300) and the second electrode part (302b) The second detector (31) is configured.

In one embodiment, the detection body (3) is connected to the first and second pyroelectric elements (300a and 300b) arranged in parallel and the first and second pyroelectric elements (300a and 300b), respectively. The first and second electrode portions (302a and 302b) are connected to each other. The first pyroelectric element (300a) and the first electrode part (302a) constitute the first detection part (31), while the second pyroelectric element (300b) and the second pyroelectric element (302a) The electrode part (302b) constitutes the second detection part (31).

The present invention has an advantage that infrared rays in different wavelength ranges can be simultaneously detected and each detection result can be output independently.

Preferred embodiments of the invention are described in further detail. Other features and advantages of the present invention will be better understood with reference to the following detailed description and accompanying drawings.
FIG. 1A is an external perspective view of the infrared detector according to the first embodiment of the present invention, and FIG. 1B is a perspective view of the infrared detector with a cap portion removed. 2A and 2B are perspective views of a circuit block in the infrared detector as viewed from the front surface side and the back surface side, respectively. 3A to 3C are explanatory diagrams of the assembly process of the circuit block. It is a perspective view which shows the inside of the circuit block. It is a perspective view of an example which shows the inside of the circuit block of the infrared detector which concerns on 1st Embodiment. It is a perspective view which shows an example of the infrared detector which concerns on 1st Embodiment in the state which removed the cap part. It is sectional drawing of the optical filter of the infrared detector which concerns on 1st Embodiment. 8A to 8C are perspective views showing a main part of an infrared detector according to the second embodiment of the present invention. 9A and 9B are a perspective view and a side view, respectively, of a main part of an infrared detector according to the third embodiment of the present invention.

(Embodiment 1)
As shown in FIG. 1, the infrared detector 1 of the present embodiment includes a detector 3 including a pyroelectric element 300 that is an infrared detection element and an IC (integrated IC) including a signal processing circuit in a metal housing 2. Circuit block 5 on which a circuit) is mounted. The ICs mounted on the circuit block 5 include the first IC 41 and the second IC 42 (see FIG. 2B). Hereinafter, when the first IC 41 and the second IC 42 are not particularly distinguished, they are simply “ IC40 ".

The casing 2 is a cap formed in a cylindrical shape having a base portion (stem) 21 made of metal and formed in a disk shape, and a flat base 221 made of metal and defining a front surface (upper surface in FIG. 1A). Part 22. The cap part 22 has an open rear surface (lower surface in FIG. 1), and is combined with the base part 21 so as to be covered from the front and joined to the base part 21 to form the housing 2. 1A shows the appearance of the infrared detector 1, and FIG. 1B shows the infrared detector 1 with the cap portion 22 removed (the cap portion 22 is indicated by a two-dot chain line).

The base part 21 has a flat disk shape, and the outer periphery of the front part 210 is set back more than the outer periphery of the rear part, and a flange part 211 is formed on the rear part. The base portion 21 is joined to the cap portion 22 by joining the opening edge of the cap portion 22 to the front surface (upper surface in FIG. 1B) of the flange portion 211. A plurality of (four in this embodiment) terminal pins 6 that are electrically connected to the circuit block 5 are inserted into the base portion 21, and the circuit block 5 inside the housing 2 and the circuit block 5 inside the housing 2 are inserted. It enables electrical connection with.

Specifically, the base portion 21 has a plurality of (four in this embodiment) through holes 212 formed inside the front surface portion 210, and the terminal pins 6 are inserted into the respective through holes 212. Here, the base portion 21 is formed such that the diameter of the through hole 212 is larger than the diameter of the terminal pin 6, and the gap between the inner peripheral surface of the through hole 212 and the terminal pin 6 is filled with a filler. Thus, the terminal pin 6 is held. A conductive filler is used for the through hole 212 through which the terminal pin 6 for ground connection is inserted, and the casing 2 is set to the ground potential, and an insulating filler is used for the other through holes 212. Thus, insulation between the housing 2 and the terminal pins 6 is ensured. A convex portion 213 for positioning is formed on a part of the outer peripheral surface of the flange portion 211.

In the central portion of the flat base 221 of the cap portion 22, a square (here, square) opening is formed as a window hole 222 for taking infrared rays into the housing 2. An optical filter 7 that transmits infrared rays is provided in the window hole 222 so as to close the window hole 222. As will be described in detail later, the detection body 3 is arranged behind (directly below) the window hole 222 in the housing 2, and thereby infrared rays transmitted through the optical filter 7 from the outside of the housing 2 are applied to the detection body 3. It will be incident.

The optical filter 7 is formed by depositing multiple layers of various metal materials on the surface of a support made of single crystal silicon. The optical filter 7 has a rectangular (rectangular) plate shape that is slightly larger than the window hole 222, and the front surface (upper surface) is dug down by one step so that the outer peripheral portion is thinner than other portions. Is adhered to the periphery of the window hole 222 on the back surface (lower surface) of the flat base 221 with a conductive adhesive or the like. As a result, the optical filter 7 also has a function as a shield for protecting against external electromagnetic noise. Furthermore, in order to improve reliability, the inner side and the outer side of the cap part 22 may be coated with urethane resin, epoxy resin, or the like.

In this embodiment, in order to reduce the height of the infrared detector 1, the cap portion 22 is set to have a depth dimension (a dimension in the front-rear direction) smaller than the outer diameter.

The detector 3 is composed of a pyroelectric element 300 formed of a material such as lithium tantalate or lead zirconate titanate (PZT) and having spontaneous polarization. In this embodiment, the pyroelectric element 300 is formed in a square plate shape. The detection body 3 can detect the amount of change in infrared rays using a phenomenon (pyroelectric effect) in which the surface charge changes according to the temperature change caused by infrared rays incident on the front surface of the pyroelectric element 300. The detection body 3 is supported by the circuit block 5 at a position facing the optical filter 7 in the housing 2 so as to be arranged behind (directly below) the window hole 222.

In the present embodiment, as shown in FIG. 1B, the detection body 3 has a plurality of detection units, for example, a first detection unit 31 and a second detection unit, which are arranged at different positions in the plane facing the optical filter 7. Part 32. Thus, the first detector 31 and the second detector 32 arranged side by side facing the optical filter 7 individually receive the infrared rays and generate the first signal and the second signal, respectively. . The first detection unit 31 and the second detection unit 32 include one pyroelectric element 300, and are configured to be point-symmetric with respect to the center of the pyroelectric element 300 as a symmetric point. Hereinafter, when the first detection unit 31 and the second detection unit 32 are not particularly distinguished, they are simply referred to as “detection unit 30”.

The first detector 31 (30) is a rectangular plate having a thickness of about 5 to 50 μm made of substantially the same material as the material forming the pyroelectric element 300 on the front and back surfaces (first and second surfaces) of the pyroelectric element 300. The first and second elements 301a (301) having a shape (only the front element is shown in FIG. 1) are formed. Similarly, the second detector 32 is a rectangular plate having a thickness of about 5 to 50 μm made of substantially the same material as the material forming the pyroelectric element 300 on the front and back surfaces (first and second surfaces) of the pyroelectric element 300. The first and second elements 301b (301) having a shape are formed. A structure for supporting the element 301 with another material is not necessary. The detection units 30 are arranged with an interval of, for example, 10 μm or more.

A first electrode portion connected to the first and second elements 301a and a second electrode portion connected to the first and second elements 301b are formed on the front surface of the pyroelectric element 300. . The first electrode portion includes two electrodes 302a (302), and the second electrode portion includes two electrodes 302b (302). Thus, the 1st detection part 31 consists of a pyroelectric element 300 and a 1st electrode part, and the 2nd detection part 32 consists of a pyroelectric element 300 and a 2nd electrode part. More specifically, the first electrode unit includes an electrode 302a connected to the first element 301a on the front side in the first detection unit 31 and an electrode 302a connected to the second element on the back side. The pyroelectric elements 300 are arranged on the first side of the front surface. The second electrode unit includes an electrode 302b connected to the first element 301b on the front surface side in the second detection unit 32 and an electrode 302b connected to the second element on the back surface side. It is arranged on the second side of the front surface of the element 300. The first side and the second side are a pair of sides facing each other in the direction in which the first detection unit 31 and the second detection unit 32 are arranged on the outer peripheral edge of the pyroelectric element 300. In short, the first and second electrode portions are connected to both ends of the pyroelectric element 300, respectively.

Further, the detection body 3 does not allow the temperature change detected by each detection unit 30 to escape to the outside, and also reduces the heat capacity of each detection unit 30 to improve the detection sensitivity. A slit 303 is formed in the part. In the example of FIG. 1, the slits 303 are formed along a pair of sides facing each other in the direction in which the first detection unit 31 and the second detection unit 32 are arranged on the outer peripheral edge of each detection unit 30. By providing such a slit 303, it is possible to suppress the influence of the thermal stress from the circuit block 5 on the detection unit 30 in a state where the detection body 3 is mounted on the circuit block 5. The width dimension of the slit 303 is, for example, at least 10 μm (10 μm or more). Note that the slits 303 may be provided on the entire periphery of the outer peripheral edge of each detection unit 30 except for the part where the wiring between the element 301 and the electrode 302 needs to be routed.

On the other hand, the circuit block 5 includes an insulating substrate 51 formed in a disk shape. The substrate 51 has a first surface facing the window hole 222 of the cap portion 22 and a second surface facing the base portion 21. The circuit block 5 supports the detection body 3 by attaching the detection body (pyroelectric element 300) 3 to the front surface (first surface) of the substrate 51. As shown in FIG. 2A, a plurality of (here, four) element connection pads 52 are formed on the front surface (upper surface) of the substrate 51, and the electrodes 302 are fixed to the element connection pads 52 with a conductive adhesive. By doing so, the detection body 3 is attached. The conductor pattern including the element connection pads 52 is formed by a metal plate, plating, or the like. Here, the conductor pattern includes a via wiring 53 (see FIG. 4) penetrating the substrate 51 in the thickness direction, and the element connection pad 52 is an IC connection pad 54 provided on the back surface of the substrate 51 through the via wiring 53. (See FIG. 2B).

The circuit block 5 uses an organic material such as glass fiber and epoxy resin, or an inorganic material such as ceramic as an insulator, and the substrate 51 is also formed of these materials (here, glass epoxy resin). Copper is mainly used as the conductor pattern, and surface treatment with silver or gold is performed according to the connection method. The substrate 51 is not limited to the structure in which the conductive pattern as described above is formed on the insulating base material, but a structure in which a metal plate (for example, a copper plate) formed in a predetermined shape is supported by a molding resin or the like. It may be.

Further, in the present embodiment, a recess 511 that secures a gap for thermal insulation between the pyroelectric element 300 and the pyroelectric element 300 is formed in a portion of the first surface of the substrate 51 that is directly behind the detection unit 30 as shown in FIG. Has been. The recess 511 is slightly smaller than the pyroelectric element 300 and is formed at a position sandwiched between the element connection pads 52 on the front surface of the substrate 51, and the pyroelectric element 300 is disposed across both sides of the recess 511. The depth of the recess 511 is set to at least 0.1 mm (0.1 mm or more), for example. By forming such a recess 511, the detection unit 30 does not directly contact the surface of the circuit block 5, so that the thermal insulation between the pyroelectric element 300 and the circuit block 5 can be taken, and the detection body 3. Increased sensitivity. However, the pyroelectric element 300 is not recessed by the recess 511 for ensuring sensitivity so that the pyroelectric element 300 is not inclined with respect to the normal of the flat base 221 of the cap portion 22 or the surface of the circuit block 5. 511 is installed on both sides.

As shown in FIG. 2B, the IC 40 is disposed on the back side of the substrate 51, and ultrasonic waves or heat and ultrasonic waves are transmitted by a thin metal wire (bonding wire) 55 with some terminals made of gold, aluminum, or copper. It is connected to the IC connection pad 54 using the wire bonding technique used together. Furthermore, in addition to the IC connection pad 54, a conductive pad for connecting the IC 40 is formed on the back surface of the substrate 51, and other terminals of the IC 40 are connected to the conductive pad by a thin metal wire 55. A plurality (four in this case) of terminal connection pads 56 for connecting the terminal pins 6 are formed on the back surface of the substrate 51 in correspondence with the terminal pins 6. The four terminal connection pads 56 are arranged at equal intervals along the outer peripheral edge of the back surface of the substrate 51 on the outer peripheral portion of the back surface of the substrate 51.

Here, the first IC 41 (40) and the second IC 42 (40) include first and second signal processing circuits, respectively, and the first detection unit 31 and the second detection unit of the detection body 3 are included. The first and second signals from 32 are configured to be processed. Each of the first and second signal processing circuits includes a first amplifier connected to the first detector 31 and a second amplifier connected to the second detector 32. Yes. The first amplification unit and the second amplification unit individually process (amplify) and output the first and second signals from the first detection unit 31 and the second detection unit 32, respectively.

In the present embodiment, the first amplifying unit is configured by the first IC 41, and the second amplifying unit is configured by the second IC 42. That is, the first IC 41 is connected to the first detection unit 31 to amplify and output the first signal from the first detection unit 31, and the second IC 42 is connected to the second detection unit 32. The second signal from the second detector 32 is amplified and output. However, it is not essential that the first amplifying unit and the second amplifying unit consist of

separate ICs

41 and 42, and one IC includes a plurality of amplifying units (first amplifying unit and second amplifying unit). May be. In this embodiment, each IC 40 includes a band-pass amplifier and a window comparator, takes out a signal of a predetermined frequency by the band-pass amplifier, and outputs H and L level signals from a window comparator in which a threshold value is set in advance.

By the way, in the infrared detector 1 of this embodiment, as shown in FIGS. 1A and 1B, the optical filter 7 includes a first transmission region 71 arranged at a position corresponding to the first detection unit 31, and a second transmission region 71. And a second transmission region 72 arranged at a position corresponding to the detection unit 32. The infrared transmission characteristics of the first transmission region 71 are different from those of the second transmission region 72. As an example, the first transmission region 71 transmits only the far infrared ray having the first wavelength (wavelength 4 μm) or more, whereas the second transmission region 72 has only the near infrared ray having the second wavelength (wavelength 2 μm) or less. Where the first wavelength is longer than the second wavelength.

That is, the optical filter 7 provided in the window hole 222 of the cap portion 22 has a plurality of transmission regions, that is, the first transmission regions 71 in the direction in which the first detection unit 31 and the second detection unit 32 are arranged. And a second transmissive region 72. In the example of FIG. 1A, the optical filter 7 is divided into two equal parts in the direction in which the first detection unit 31 and the second detection unit 32 are arranged, and the portion facing the first detection unit 31 is the first transmission. The portion that becomes the region 71 and faces the second detection unit 32 becomes the second transmission region 72.

In other words, the first detection unit 31 is located in the vertical projection plane of the first transmission region 71 with respect to the front surface of the detection body 3, and the second detection unit 32 is perpendicular to the second transmission region 72 with respect to the front surface of the detection body 3. Located in the projection plane. Therefore, when infrared rays are incident on the window hole 222, infrared rays that have passed through the first transmission region 71 are incident on the first detection unit 31, and the second detection region 32 is transmitted through the second transmission region 72. Incident infrared rays. Here, since the infrared transmission characteristics of the first transmission region 71 are different from those of the second transmission region 72, the first detection unit 31 and the second detection unit 32 simultaneously receive infrared rays having different wavelength ranges. It will be incident.

As described above, the output of the first detection unit 31 and the output of the second detection unit 32 are mutually transmitted by the first IC (first amplification unit) 41 and the second IC (second amplification unit) 42. Since the processing is performed independently and independently, the output of the first detection unit 31 and the output of the second detection unit 32 are not mixed. Therefore, since the infrared detector 1 outputs separately the detection results corresponding to the infrared rays having different wavelength ranges incident on the first detection unit 31 and the second detection unit 32 at the same time, as a result, different wavelength ranges are obtained. Infrared rays can be detected at the same time, and each detection result can be output independently.

Here, the optical filter 7 is formed by a method such as vapor deposition using a metal mask on a single silicon single crystal support, for example, transmission regions having different transmission characteristics (the first transmission region 71 and the second transmission region). 72) is formed. However, the present invention is not limited to this configuration, and a plurality of (two) optical filters having different transmission characteristics are separated into individual pieces, and the plurality of optical filters are arranged side by side and attached to the support, whereby the first optical filter is used for each optical filter. The transmissive region 71 and the second transmissive region 72 may be configured.

Here, the infrared transmission characteristics are not limited to the wavelength range, and may be, for example, the polarization direction. In this case, the first transmission region 71 and the second transmission region 72 are made of polarizing filters having different polarization directions, and the first detection unit 31 and the second detection unit 32 simultaneously receive infrared rays having different polarization directions. It will be incident. In this case, the infrared transmission wavelength (for example, 4 μm or more) of the first transmission region 71 may be the same as that of the second transmission region 72.

Next, the assembly procedure of the infrared detector 1 described above will be briefly described with reference to FIG. 3A to 3C show a state in which the circuit block 5 is viewed from the mounting surface (hereinafter referred to as the back surface) side of the IC 40. FIG.

As shown in FIG. 3A, the worker who performs the assembly mounts and fixes each IC 40 on the back surface of the substrate 51 on which the conductor pattern is formed with epoxy resin or the like, and further attaches each IC 40 to the conductor pattern on the substrate 51 with the metal thin wire 55. Conductive connection with. The connection between the conductor pattern and the terminal of the IC 40 is performed by using a combination of heating and ultrasonic waves using a thin metal wire 55 such as aluminum, gold, or copper, or by using only ultrasonic waves. Performed by solid phase diffusion.

Thereafter, as shown in FIG. 3B, the operator mounts and adheres a synthetic resin sealing frame 57 to the back surface of the substrate 51. The sealing frame 57 is formed in a substantially annular shape that is slightly smaller than the outer periphery of the back surface of the substrate 51, and the height dimension from the back surface of the substrate 51 is at least larger than the IC 40 and the fine metal wire 55. Further, in the sealing frame 57, the portions corresponding to the four terminal connection pads 56 are recessed inward so as to avoid the terminal connection pads 56.

Then, as shown in FIG. 3C, the operator fills the sealing frame 57 with a sealing material 58 such as a liquid epoxy resin and heat cures the sealing material 58. The enclosed IC 40 and fine metal wire 55 are sealed with a sealing material 58. At this time, the sealing material 58 is prevented from turning around the front surface of the substrate 51 (the mounting surface of the detection unit 3) and the terminal connection pads 56.

Thereafter, the operator turns the board 51 upside down so that the mounting surface of the detection unit 3 faces up, mounts and bonds the board 51 to the central portion of the front surface of the base 21 holding the terminal pins 6, and faces the terminal pins 6 facing each other. And the terminal connection pad 56 are made conductive with a conductive adhesive or the like. Then, the operator places the pyroelectric element 300 on the substrate 51 and fixes the electrode 302 to the element connection pad 52 with a conductive adhesive, thereby fixing the detector 3 to the circuit block 5 and electrically connecting it. In addition, the terminal connection pad 56 connected to the terminal pin 6 may have a shape in which a step is formed and a conductive adhesive can be applied from a gap between the terminal pin 6 and the terminal pin 6 generated by the step.

Then, the operator joins the cap portion 22 to the base portion 21 by a method such as resistance welding, and seals the detection body 3 and the circuit block 5 in the metal housing 2. The housing 2 is a so-called CAN package, which can improve the shielding effect against external noise and improve weather resistance by improving airtightness.

In addition, the change in surface charge due to the incidence of infrared rays on the detection body 3 including the pyroelectric element 300 is very small. On the other hand, the IC 40 constituting the signal processing circuit generates a relatively large output of the detection body 3 in the housing 2. Amplify to signal. Therefore, it is desirable to provide a function for preventing the detection body 3 and the IC 40 from being capacitively coupled also in the housing (CAN package) 2 that protects against electromagnetic noise.

Therefore, in this embodiment, in order to prevent malfunction due to capacitive coupling between the output of the IC 40 and the detector 3, a shield plate 59 having a ground potential is provided in the circuit block 5 as shown in FIG. The shield plate 59 is a thin plate-like conductor parallel to the back surface of the substrate 51, and is embedded in the substrate 51 so as to be positioned between the detection body 3 and the IC 40. The detection body 3 and the IC 40 are connected to each other. The through-hole 591 is vacant only in the portion through which the via wiring 53 to be connected is passed.

Furthermore, in order to prevent the electric charge generated in the detection body 3 from leaking to the ground due to the proximity of the shield plate 59 of the ground potential and the via wiring 53, as shown in FIG. A reference pattern 592 of the reference potential of the signal processing circuit may be provided in the 591. The reference pattern 592 is formed in an arc shape that is separated from the periphery of the through hole 591 of the shield plate 59 and surrounds one via wiring 53 of the pair of via wirings 53 connected to each detection unit 30. It is connected to the other via wiring 53. The shield plate 59 and the reference pattern 592 are not limited to a structure in which a pattern formed on an insulating base material constituting the substrate 51 is formed, but a metal plate (copper plate) formed in a predetermined shape. A structure in which a conductive adhesive is attached to the material may be used.

In addition, the terminal pin 6 may be configured to penetrate the substrate 51 and be connected to the circuit block 5 on the mounting surface side of the detection unit 3 in the substrate 51. However, in this case, a shield plate 59 that prevents capacitive coupling between the output of the IC 40 and the detection body 3 is also disposed between the terminal pin 6 connected to the output of the IC 40 and the detection body 3. Is desirable.

According to the infrared detector 1 of the present embodiment described above, since the transmission characteristics of the first transmission region 71 of the optical filter 7 are different from those of the second transmission region 72, the first detector 31 and the second detector The detection unit 32 can simultaneously detect infrared rays having different wavelength ranges. Further, the output of the first detection unit 31 and the output of the second detection unit 32 are separately processed by the first IC (first amplification unit) 41 and the second IC (second amplification unit) 42. Therefore, infrared rays in different wavelength ranges can be detected simultaneously, and each detection result can be output independently.

Therefore, by using the output of this infrared detector 1, for example, the type of detection target can be identified and noise can be removed. In other words, if the distribution of the infrared fluctuation amount for each wavelength range is known, it is possible to identify the type of the detection target from this distribution, and from the difference in the infrared fluctuation amount in different wavelength ranges, from the detection target such as a human body. Detection that removes noise components such as environmental temperature becomes possible. Specifically, the infrared detector 1 sets a plurality of wavelength ranges to be detected, thereby distinguishing and detecting heat sources having different temperatures, such as humans and small animals, and improving detection accuracy by comparing with reference light. It becomes possible.

Further, the infrared transmission wavelengths of the first transmission region 71 and the second transmission region 7 are set to the same value (for example, 4 μm or more), and the polarization directions of the first transmission region 71 and the second transmission region 72 are made different. Thus, the moving direction (vertical, horizontal) of the heat source can be determined from the output of the infrared detector 1. For example, a filter having a large number of grooves on the surface is used as the optical filter 7, and the movement direction of the heat source (similarly by changing the direction of the grooves in the first transmission region 71 and the second transmission region 72 ( (Vertical, horizontal) can be discriminated.

In this embodiment, since the pyroelectric element 300 is fixed to the circuit block 5, thermal stress from the circuit block 5 may be applied to the pyroelectric element 300. Since the surface charge of the pyroelectric element 300 also responds to stress, the detector 3 may generate an output in response to the thermal stress from the circuit block 5 regardless of the incidence of infrared rays. In particular, if a thermal stress is applied to the detection unit 30, the signal is directly output as a signal. Therefore, it is desirable to reduce the influence of the thermal stress on the pyroelectric element 300 as much as possible.

Here, the pyroelectric element 300 is fixed to the circuit block 5 with each electrode 302 as a fixing point by fixing the electrodes 302 formed at four places to the element connection pads 52 of the circuit block 5 with a conductive adhesive. Has been. If these four fixed electrodes 302 are arranged one by one on each side of the front surface of the pyroelectric element 300, depending on the difference in coefficient of linear expansion and elastic coefficient with the circuit block 5. Since the applied stress is applied to the pyroelectric element 300 from each side, the influence of the thermal stress becomes relatively large.

On the other hand, in this embodiment, the four electrodes 302 as these fixed points are on a pair of sides (first side, second side) facing each other on the front surface of the pyroelectric element 300 as described above. They are arranged separately. That is, the fixed points of the pyroelectric element 300 are both positioned on a pair of sides facing each other on the surface of the pyroelectric element 300. Thereby, the thermal stress from the circuit block 5 to the pyroelectric element 300 can be unidirectional, and there is an advantage that the influence of the thermal stress can be reduced.

Furthermore, in the present embodiment, the detection body 3 does not allow the temperature change detected by each detection unit 30 to escape to the outside, and each detection unit 30 has a reduced heat capacity to improve detection sensitivity. A slit 303 is formed in a part of the outer peripheral edge of the. Since the slit 303 is formed between the electrode 302 as a fixed point and the detection unit 30, thermal stress from the circuit block 5 to the detection unit 30 can be further reduced.

By the way, the detection body 3 may further include a detection unit in addition to the two detection units 30 of the first detection unit 31 and the second detection unit 32. That is, the detection body 3 includes at least the first detection unit 31 and the second detection unit 32 such as the first detection unit 31, the second detection unit 32, the third detection unit, and so on. One pyroelectric element 300 may have three or more detection units. For example, when there are first to third detection units, the third detection unit is connected to the third amplification unit, and the optical filter 7 includes the first transmission region 71, the second transmission region 72, The infrared transmission characteristics are different from those of the third transmission region arranged at a position corresponding to the three detection units. In this manner, by providing a separate amplifying unit for each detection unit and further providing transmission regions having different transmission characteristics, even if the detection body 3 has three or more detection units, each detection unit is different. Infrared rays in the wavelength range can be detected simultaneously, and each detection result can be output independently.

The arrangement of a plurality of (two or more) detectors on the pyroelectric element 300 constituting the detector 3 may be a matrix, a row, or a random.

Further, as shown in FIG. 6, the detection body 3 may include a plurality of pyroelectric elements 300, and the first detection unit 31 and the second detection unit 32 may be formed in separate pyroelectric elements 300. In the example of FIG. 6, the detection body 3 includes a first pyroelectric element 300a (300) and a second pyroelectric element 300b (300), and the first detection unit 31 is formed by the first pyroelectric element 300a. Thus, the second detection unit 32 is formed by the second pyroelectric element 300b. These pyroelectric elements 300 are arranged on the front surface of the substrate 51 at a predetermined interval. Each pyroelectric element 300 has at least two electrodes 302, and each electrode 302 is fixed to the circuit block 5 by fixing the electrode 302 to the element connection pad 52 of the circuit block 5 with a conductive adhesive. Connected. Furthermore, even when the detection body 3 includes a plurality of pyroelectric elements 300, a plurality of detection units may be formed in each pyroelectric element 300.

Further, as shown in FIG. 7, the optical filter 7 may be formed using single crystal silicon having a curved surface so as to have a light collecting function. In the example of FIG. 7, the optical filter 7 has a curved surface on the front surface (front surface) exposed from the window hole 222 to the outside of the housing 2, whereby infrared rays transmitted through the optical filter 7 are collected in the detection unit 30. To be lighted.

In the conductor pattern of the circuit block 5, the wiring between the detector 3 and the IC 40 has sufficient insulation (for example, 1 TΩ or more) with respect to the wiring of other potential. The IC 40 including the signal processing circuit is formed by using a semiconductor integrated circuit manufacturing technique, and is formed on the surface of a silicon single crystal. Therefore, a plurality of amplifying sections (first amplifying section and second amplifying section) may be formed on the surface of a single silicon single crystal, or amplifying sections may be formed individually on each of the plurality of silicon single crystals. May be.

Further, the connection of the detection body 3 and the power source to the signal processing circuit (IC 40) is not limited to the wire bonding technique, but the flip chip technique using the metal protrusion formed on the electrode on the silicon single crystal, or copper or eutectic metal. You may perform using the soldering technique using. Alternatively, a multi-component eutectic metal may be bonded with a material having a melting point of 300 ° C. or higher after heat treatment at a temperature of 250 ° C. or lower. In any connection method, it is desirable to protect the vicinity of the connection interface with a sealing material 58 such as an epoxy resin, a urethane resin, or a silicone resin in order to protect from the external environment and ensure strength.

Further, the infrared detector 1 is not limited to use as a human body detection, but may be used as a gas sensor, for example. Specific examples of infrared transmission characteristics of the first transmission region 71 and the second transmission region 72 when used as a gas sensor are shown below.

The first transmission region 71 is a band-pass filter having a transmission center wavelength of 4.26 μm and a half-value width of 0.18 μm, and the second transmission region 72 is a band-pass filter having a transmission center wavelength of 3.95 μm and a half-value width of 0.16 μm. It may be used vessel 1 as CO ₂ sensor. In this case, infrared rays that pass through the first transmission region 71 and enter the first detection unit 31 become the detection wavelength range, and infrared rays that pass through the second transmission region 72 and enter the second detection unit 32 This is the reference wavelength region.

On the other hand, the first transmission region 71 is a bandpass filter having a transmission center wavelength of 3.30 μm and a half width of 0.16 μm, and the second transmission region 72 is a transmission center wavelength of 3.95 μm and a half width of 0.16 μm. The infrared detector 1 can be used as a CH ₄ sensor. In this case, infrared rays that pass through the first transmission region 71 and enter the first detection unit 31 become the detection wavelength range, and infrared rays that pass through the second transmission region 72 and enter the second detection unit 32 This is the reference wavelength region.

(Second Embodiment)
The infrared detector 1 of this embodiment is different from the infrared detector 1 of the first embodiment in that the optical filter 7 has a different area for each transmission region. Below, the same code | symbol is attached | subjected about the structure similar to Embodiment 1, and description is abbreviate | omitted suitably.

That is, in the present embodiment, in the optical filter 7, the area of the first transmission region 71 is different from that of the second transmission region 72 as shown in FIGS. 8A to 8C. In the example of FIG. 8A, the optical filter 7 is not divided into two equal parts, and the second transmission region 72 is divided so as to be larger than the first transmission region 71. In the example of FIG. 8B, the window hole 222 is formed in a shape in which the width of the portion corresponding to the second transmission region 72 is made smaller than the portion corresponding to the first transmission region 71, and the second transmission region 72 is formed. It is smaller than the first transmission region 71. In the example of FIG. 8C, two window holes 222 are provided, and the window hole 222 provided with the second transmission region 72 is formed smaller than the window hole 222 provided with the first transmission region 71. The second transmission region 72 is smaller than the first transmission region 71.

Since the first transmission region 71 and the second transmission region 72 have different infrared transmission characteristics, the infrared transmission factor itself may be different. However, as described above, the area of the first transmission region 71 is the first transmission region 71. By configuring the optical filter 7 so as to be different from that of the two transmission regions 72, the difference in transmittance can be absorbed. In short, the transmittance of the first transmission region 71 and the second transmission region 72 so that there is no bias between the amount of infrared light incident on the first detection unit 31 and the amount of infrared light incident on the second detection unit 32. It is sufficient that the light receiving area of each transmission region is adjusted according to the above.

In addition, the area of each detection unit 30 in the detection body 3 may also be changed according to the transmission region. Other configurations and functions are the same as those in the first embodiment.

(Third embodiment)
As shown in FIGS. 9A and 9B, the infrared detector 1 of the present embodiment is disposed in a space between the detector 3 and the optical filter 7 in the housing 2, and the space is connected to the first detector 31. The infrared detector according to the first embodiment is different from the first embodiment in that a partition 8 for partitioning with the second detector 32 is provided. Below, the same code | symbol is attached | subjected about the structure similar to Embodiment 1, and description is abbreviate | omitted suitably.

That is, in the infrared detector 1 of the present embodiment, the detection body 3 has a plurality of detection units 30 and the outputs of the detection units 30 are processed by separate amplification units. A partition 8 is provided between the plurality of detection units 30 so that interference does not occur as much as possible. The partition 8 is formed between adjacent detectors 30 and prevents infrared rays incident on each detector 30 from interfering with other detectors 30. That is, the partition 8 partitions the space between the detection body 3 and the optical filter 7 in the housing 2, and the infrared light that has passed through the first transmission region 71 enters the second detection unit 32. The infrared rays transmitted through the second transmission region 72 are prevented from entering the first detection unit 31.

The partition 8 may be formed, for example, on the surface of the circuit block 5 by molding, or may be configured as a separate member from the circuit block 5 and fixed (adhered) on the circuit block 5. The partition 8 may be formed of a support (silicon single crystal) or a vapor deposition body of the optical filter 7, or may be formed as a separate member from the optical filter 7 and fixed (adhered) to the optical filter 7. Good. Further, the partition 8 may be formed integrally with the cap part 22 by a metal constituting the cap part 22, or may be configured as a separate member from the cap part 22 and fixed (adhered) to the cap part 22.

According to the configuration of the present embodiment described above, by providing the partition 8, it is possible to prevent the infrared rays transmitted through the first transmission region 71 from entering the second detection unit 32, and the second transmission region. Infrared rays that have passed through 72 can be prevented from entering the first detector 31. Therefore, it is possible to suppress infrared interference between the plurality of detection units 30.

Furthermore, the partition 8 may be formed of a material that reflects infrared light, or may be subjected to surface treatment such as mirror finishing so that the surface thereof forms a reflective surface that reflects infrared light. In this case, since the infrared light incident on the partition 8 is reflected by the surface of the partition 8 and enters the detection unit 30, the provision of the partition 8 can suppress a reduction in the amount of infrared light incident on the detection unit 30.

In addition, the partition 8 demonstrated by this embodiment is not restricted to the structure of 1st Embodiment, You may employ | adopt in combination with the structure of 2nd Embodiment. Other configurations and functions are the same as those in the first embodiment.

Claims

A detector comprising first and second detectors, each comprising at least one pyroelectric element and configured to generate first and second signals, respectively;
A circuit block comprising first and second amplifiers configured to amplify the first and second signals, respectively;
A housing having a window hole and housing the detector and the circuit block;
An optical filter provided in the window hole and configured to transmit infrared rays,
The optical filter includes first and second transmission regions at positions corresponding to the first and second detection units, respectively.
The optical filter is configured so that an infrared transmission characteristic of the first transmission region is different from that of the second transmission region.
The circuit block comprises a signal processing circuit configured to process a signal from the sensing body,
The housing is
A base portion through which a terminal pin electrically connected to the circuit block is inserted;
A cap part that forms a metal casing together with the base part,
The window hole is an opening provided in a part of the cap portion,
The detector is supported by the circuit block at a position facing the optical filter in the housing,
The infrared detector according to claim 1, wherein the first and second detection units are arranged at different positions in a plane along the optical filter.
The infrared detector according to claim 2, wherein an area of the first transmission region is different from that of the second transmission region.
The apparatus further comprises a partition that is disposed in a space between the detection body and the optical filter in the housing and partitions the space between the first detection unit and the second detection unit. The infrared detector according to claim 2 or 3.
The infrared detector according to claim 4, wherein the partition has a surface on which a reflection surface for reflecting infrared rays is formed.
6. The infrared detector according to claim 2, wherein the detector comprises first and second pyroelectric elements that constitute the first and second detectors, respectively. .
The pyroelectric element has a rectangular plate shape and is fixed to the circuit block at at least four fixing points;
The infrared detector according to any one of claims 2 to 6, wherein each of the at least four fixed points is positioned on a pair of sides facing each other on a plate surface of the pyroelectric element.
The circuit block includes a substrate having a first surface facing the window hole and a second surface facing the base portion,
The detector is attached to the first surface of the substrate,
The infrared detector according to any one of claims 2 to 7, wherein the electronic component constituting the signal processing circuit is attached to the second surface of the substrate.
The detector comprises the pyroelectric element and first and second electrode portions connected to both ends of the pyroelectric element,
The pyroelectric element and the first electrode part constitute the first detection part, while the pyroelectric element and the second electrode part constitute the second detection part. Item 1. The infrared detector according to Item 1.
The detection body includes first and second pyroelectric elements arranged in parallel, and first and second electrode portions connected to the first and second pyroelectric elements, respectively.
The first pyroelectric element and the first electrode part constitute the first detection part, while the second pyroelectric element and the second electrode part constitute the second detection part. The infrared detector according to claim 1.