JP5741924B2 - Infrared sensor - Google Patents

Description

  The present invention relates to an infrared sensor that detects infrared rays from a measurement object and measures the temperature or the like of the measurement object.

Conventionally, an infrared sensor is used as a temperature sensor that detects the temperature of an object to be measured by detecting infrared rays radiated from the object to be measured in a non-contact manner.
For example, in Patent Document 1, a resin film installed on a holding body, an infrared detection thermal element that is provided on the resin film and detects infrared rays through a light guide portion of the holding body, and a light shielding state is provided on the resin film. There has been proposed an infrared temperature sensor including a temperature-compensating thermosensitive element for detecting the temperature of the holder. In this infrared temperature sensor, an infrared absorption film is formed on the inner side surface of the light guide portion, and an infrared absorption material such as carbon black is contained in the resin film to enhance infrared absorption. The infrared temperature sensor is provided in a holding body formed of a metal material having a high thermal conductivity such as aluminum.

Patent Document 2 discloses a thermal sensing element for detecting infrared rays, a thermal sensing element for temperature compensation, a resin film for tightly fixing them, a thermal sensing element for detecting infrared rays on the infrared incident window side, and a shield for shielding infrared rays. And an infrared detector including a case having a frame body in which a temperature-compensating thermosensitive element is disposed on the part side. In this infrared detector, an infrared absorbing material such as carbon black is included in the resin film to enhance infrared absorption, and heat conduction is performed to eliminate the thermal gradient between the infrared detecting thermal element and the temperature compensating thermal element. The frame is made of a good material. In addition, a pine needle type thermistor in which a lead wire is connected to the thermistor is employed in the infrared detecting thermal element and the temperature compensating thermal element. This infrared detector is fixed in a resin or metal case.
In these infrared sensors of Patent Documents 1 and 2, a structure in which an infrared absorbing material such as carbon black is contained in a resin film and one heat sensitive element side is shielded for temperature compensation is used. The heat conduction of the resin film is high, and there is a disadvantage that a temperature difference is hardly generated between the thermal sensing elements for infrared detection and temperature compensation. Also, in order to increase the temperature difference between these thermal elements, it is necessary to increase the distance between the thermal elements, which increases the overall shape and makes it difficult to reduce the size. Furthermore, since it is necessary to provide the case itself with a structure that shields the temperature-compensating thermal element, the cost is increased.
Moreover, in patent document 2, since the frame body with favorable heat conductivity is employ | adopted, the heat from an infrared rays absorption film is also thermally radiated and there exists a problem that a sensitivity deteriorates. In addition, because of the pine needle type to which the lead wire is connected, heat conduction occurs between the thermistor and the lead wire.
In addition, the heat-sensitive element has a structure that shields infrared rays with a housing, but the shielding part absorbs infrared rays only by shielding the infrared rays, and the temperature of the shielding part changes. There was an inconvenience of being incomplete as a reference.

  Therefore, as shown in Patent Document 3, the insulating film, the first thermal element and the second thermal element provided on one surface of the insulating film and separated from each other, and one of the insulating films A plurality of pairs of conductive wiring films formed on the surface and separately connected to the first thermal element and the second thermal element, and provided on the other surface of the insulating film facing the first thermal element. An infrared sensor has been developed that includes an infrared absorbing film and an infrared reflecting film provided on the other surface of the insulating film so as to face the second thermosensitive element. The infrared sensor is supported by a resin casing.

  In this infrared sensor, the first thermal element and the second thermal element are formed on a thin insulating film with low thermal conductivity by partial infrared absorption by the infrared absorption film and partial infrared reflection by the infrared reflection film. A good temperature difference can be obtained. That is, even with a low thermal conductive insulating film that does not contain an infrared absorbing material or the like in the film, the infrared absorbing film can conduct heat due to infrared absorption only to the portion directly above the first thermal element of the insulating film. . In particular, since the heat of the infrared absorption film is conducted across a thin insulating film, the sensitivity is not deteriorated and the response is high. In addition, since the area of the infrared absorption film can be arbitrarily set, the viewing angle of infrared detection matched to the distance to the measurement object can be set by area, and high light receiving efficiency can be obtained. Moreover, the infrared ray can be reflected by the infrared reflection film to prevent the absorption of the infrared ray at the portion directly above the second heat sensitive element of the insulating film. In addition, since the infrared absorption film and the infrared reflection film are formed on the insulating film, the medium that conducts heat between the infrared absorption film and the infrared reflection film is between these films other than air. It becomes only an insulating film and the cross-sectional area to conduct becomes small. Accordingly, it is difficult for heat to be transmitted to the mutual heat sensitive elements, interference is reduced, and detection sensitivity is improved. As described above, the first heat sensitive element and the second heat sensitive element in which the influence of heat is suppressed on the insulating film having low thermal conductivity are respectively insulated from directly below the infrared absorbing film and directly below the infrared reflecting film. It has a structure for measuring the partial temperature of the adhesive film. Therefore, it is possible to obtain a good temperature difference between the first thermosensitive element used for infrared detection and the second thermosensitive element used for temperature compensation, thereby achieving high sensitivity.

JP 2002-156284 A (paragraph number 0026, FIG. 2) JP-A-7-260579 (Claims, FIG. 2) Japanese Patent Laying-Open No. 2011-13213 (Claims, FIG. 1)

The following problems remain in the conventional technology.
That is, the conventional infrared sensor is installed in a case made of resin or metal, but when the case itself is overheated and emits radiant heat, the sensitivity of the infrared sensor that has received the radiant heat may change. For example, in the case of the infrared sensor of Patent Document 3, as shown in FIGS. 7 and 8, when the housing 7 is overheated by infrared rays transmitted through the insulating film 2 and emits radiant heat, the insulating film 2 that receives the radiant heat is used. There is a disadvantage that the sensitivity of the thermal element 3A and the thermal element 3B changes due to a change in temperature. Further, if there is a temperature difference between the housing 7 and the insulating film 2, there is a possibility that the temperature detection is affected by the radiant heat from the housing 7. If the housing 7 is made of low-cost resin instead of high-cost metal, the characteristics change due to the emissivity of the resin used. Since it changed, there was a problem that high-precision measurement was difficult.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an infrared sensor capable of suppressing the influence of radiant heat from a housing.

  The present invention employs the following configuration in order to solve the above problems. That is, the infrared sensor of the first invention includes an insulating film, a first thermal element and a second thermal element provided on one surface of the insulating film so as to be separated from each other, and the insulating film. A conductive first wiring film formed on one surface and connected to the first thermosensitive element, a conductive second wiring film connected to the second thermosensitive element, and the second thermosensitive element An infrared reflecting film provided on the other surface of the insulating film facing the element, and fixed to one surface of the insulating film to support the insulating film, and the first thermosensitive element and the A housing for storing the second thermosensitive element in an internal storage portion, and the first wiring film is arranged up to the periphery of the first thermosensitive element and has a larger area than the second wiring film. It is formed by.

  The infrared sensor includes a housing that supports the insulating film and accommodates the first and second heat sensitive elements in an inner accommodating portion, and the first wiring film surrounds the first heat sensitive element. Since the first wiring film having a larger area blocks the infrared rays that are transmitted through the insulating film and irradiate the casing, the first wiring film has a larger area than the second wiring film. It can block the radiant heat radiated from the body and suppress the thermal effect on the insulating film. Furthermore, the heat collection from the portion of the insulating film that absorbs infrared rays is improved, and the heat capacity is close to that of the portion of the insulating film where the infrared reflecting film is formed, so that the fluctuation error can be reduced. The area and shape of the first wiring film are preferably set so that the heat capacity is substantially equal to the portion of the insulating film where the infrared reflective film is formed.

The infrared sensor of the second invention is characterized in that, in the first invention, the first wiring film and the infrared reflecting film are shaped so as to close an upper portion of the storage portion in plan view.
That is, in this infrared sensor, since the first wiring film and the infrared reflecting film are shaped so as to block the upper part of the housing portion in plan view, the insulating film is formed by the first wiring film and the infrared reflecting film. Infrared rays that pass through and enter the storage portion can be blocked by the entire upper portion of the storage portion, and the case can be further suppressed from being heated.

The infrared sensor of the third invention is characterized in that, in the first or second invention, a bottom surface reflecting film for reflecting infrared rays is formed on the bottom surface facing the insulating film in the casing.
That is, in this infrared sensor, a bottom surface reflecting film that reflects infrared rays is formed on the bottom surface facing the insulating film in the housing, so that the radiant heat radiated from the bottom surface in the housing is directly reflected by the bottom surface reflecting film. By blocking this, it is possible to further suppress the influence on the opposing insulating film and thermal element.

An infrared sensor of a fourth invention is characterized in that, in any one of the first to third inventions, the casing is formed of a resin.
That is, in this infrared sensor, since the housing is formed of resin, it can be manufactured at a lower cost than in the case of metal.

The present invention has the following effects.
That is, according to the infrared sensor according to the present invention, the first wiring film is arranged up to the periphery of the first thermal element and is formed with a larger area than the second wiring film. The first wiring film blocks infrared rays that pass through the insulating film, and further blocks the radiant heat from the casing to suppress the thermal effect on the insulating film, and the heat capacity with the portion where the infrared reflecting film is formed. As the value approaches, the fluctuation error can be reduced and the temperature can be detected with high accuracy.

It is sectional drawing which shows one Embodiment of the infrared sensor which concerns on this invention. In this embodiment, it is the bottom view (a) which shows the insulating film before a thermal element is adhere | attached, and the bottom view (b) which shows the positional relationship of a wiring film, a storage part, and an infrared reflective film. In this embodiment, it is a top view which shows the insulating film before a thermal element is adhere | attached. In this embodiment, it is a perspective view which shows an infrared sensor. In this embodiment, it is a perspective view which shows the infrared sensor except a housing | casing. In this embodiment, it is a top view which shows a housing | casing. In the comparative example of the infrared sensor which concerns on this invention, it is a bottom view which shows the insulating film before a thermal element is adhere | attached. It is sectional drawing which shows the comparative example of the infrared sensor which concerns on this invention.

  Hereinafter, an infrared sensor according to an embodiment of the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

  As shown in FIGS. 1 to 4, the infrared sensor 1 of the present embodiment includes an insulating film 2 and a first thermosensitive element provided on one surface (lower surface) of the insulating film 2 so as to be separated from each other. 3A and the second thermal element 3B, and a pair of first wiring film 4A and second thermal element which are conductive metal films formed on one surface of the insulating film 2 and connected to the first thermal element 3A. A pair of second wiring films 4B that are conductive metal films connected to the element 3B; an infrared reflecting film 6 provided on the other surface of the insulating film 2 so as to face the second thermal element 3B; A casing 7 fixed to one surface of the insulating film 2 to support the insulating film 2 and store the first thermal element 3A and the second thermal element 3B in the internal storage portion 7a. Yes.

  As shown in FIG. 2, the first wiring film 4A is arranged up to the periphery of the first thermal element 3A and has a larger area than the second wiring film 4B. These first wiring films 4 </ b> A are provided with the first thermosensitive element 3 </ b> A at the center of a pair, and the outer shape of the pair is set to be substantially the same as the infrared reflecting film 6. That is, the area and shape of the first wiring film 4A are set so that the heat capacity is substantially equal to the portion of the insulating film 2 where the infrared reflective film 6 is formed.

  Further, the first wiring film 4A and the infrared reflecting film 6 have a shape that covers the upper portion of the storage portion 7a in plan view. That is, as shown in FIG. 2B, when viewed from the upper side of the insulating film 2 (plan view), a pair of outer shapes are set to be substantially the same square shape as the infrared reflective film 6. The one wiring film 4A and the infrared reflecting film 6 close up substantially the entire upper portion of the rectangular parallelepiped storage portion 7a.

The pair of first wiring films 4A is connected to the first adhesive electrode 5A formed on the insulating film 2 at one end thereof and to the other end portion on the insulating film 2 respectively. The first terminal electrode 8 </ b> A formed on is connected.
Further, the pair of second wiring films 4B are formed in a linear shape, and one end portion thereof is connected to the second adhesive electrode 5B formed on the insulating film 2, and the other end portion. A second terminal electrode 8B formed on the insulating film 2 is connected to each other.
Note that the terminal electrodes 3a of the first heat sensitive element 3A and the second heat sensitive element 3B are bonded to the first adhesive electrode 5A and the second adhesive electrode 5B, respectively, with a conductive adhesive such as solder.

  The insulating film 2 is formed of a polyimide resin sheet, and the infrared reflection film 6, the first wiring film 4A, and the second wiring film 4B are formed of copper foil. That is, these are both surfaces in which the float electrode of copper foil used as the infrared reflecting film 6, the first wiring film 4A and the second wiring film 4B is patterned on both surfaces of the polyimide substrate used as the insulating film 2. It is made of a flexible substrate.

Further, as shown in FIG. 3, the infrared reflection film 6 is arranged in a square shape immediately above the second heat sensitive element 3B, and is composed of a copper foil and a gold plating film laminated on the copper foil. Has been.
The infrared reflecting film 6 is formed of a material having an infrared emissivity higher than that of the insulating film 2 and is formed by applying a gold plating film on the copper foil as described above. In addition to the gold plating film, for example, a mirror-deposited aluminum vapor deposition film or an aluminum foil may be used. The infrared reflecting film 6 is formed to cover the second thermal element 3B with a size larger than that of the second thermal element 3B.

  The first thermal element 3A and the second thermal element 3B are chip thermistors in which terminal electrodes 3a are formed at both ends as shown in FIG. As this thermistor, there are thermistors of NTC type, PTC type, CTR type and the like. In this embodiment, for example, NTC type thermistors are employed as the first thermal element 3A and the second thermal element 3B. This thermistor is formed of a thermistor material such as a Mn—Co—Cu-based material or a Mn—Co—Fe-based material. The first thermal element 3A and the second thermal element 3B are mounted on the insulating film 2 by bonding the terminal electrodes 3a onto the corresponding first adhesive electrode 5A or the second adhesive electrode 5B. Has been.

  In particular, in the present embodiment, the first thermal element 3A and the second thermal element 3B are formed of a ceramic sintered body containing a metal oxide of Mn, Co, and Fe, that is, an Mn—Co—Fe-based material. Thermistor element is used. Furthermore, this ceramic sintered body preferably has a crystal structure having a cubic spinel phase as a main phase. In particular, as a ceramic sintered body, a single-phase crystal structure composed of a cubic spinel phase is most desirable.

The casing 7 is made of a resin such as PPS (polyphenylene sulfide resin), and houses the first thermal element 3A and the second thermal element 3B, and has an air conductivity lower than that of the insulating film 2. A storage portion 7a which is a space covered with is provided inside.
A bottom surface reflecting film 9 that reflects infrared rays is formed on the bottom surface of the housing 7 facing the insulating film 2. As the bottom reflective film 9, a film similar to the infrared reflective film 6 can be adopted.

  As shown in FIGS. 4 and 6, the housing 7 is provided on the side surface and has an upper end connected to the second terminal electrode 8B of the first wiring film 4A or the second wiring film 4B and extends to the bottom. A plurality of side electrode portions 10a are provided, and a plurality of mounting external terminals 10b are provided that are connected to the lower end of the side electrode portion 10a at the lower portion of the side surface and are connected to an external circuit board. That is, the infrared sensor 1 of the present embodiment is a surface mount type. The side electrode part 10a and the mounting external terminal 10b are made of, for example, a tin-plated copper alloy.

  As described above, the infrared sensor 1 of the present embodiment includes the housing 7 that supports the insulating film 2 and stores the first thermal element 3A and the second thermal element 3B in the internal storage portion 7a. Since the wiring film 4A is arranged up to the periphery of the first thermosensitive element 3A and has a larger area than the second wiring film 4B, the first wiring film 4A having a larger area is formed of an insulating film. The infrared rays that pass through 2 and irradiate the casing 7 can be blocked, and the radiant heat radiated from the casing 7 can be blocked to suppress the thermal effect on the insulating film 2. Furthermore, the heat collection from the portion of the insulating film 2 that absorbs infrared rays is improved, and the heat capacity is close to the portion of the insulating film 2 where the infrared reflective film 6 is formed, so that the fluctuation error can be reduced.

In addition, since the first wiring film 4A and the infrared reflection film 6 are shaped to close the upper portion of the storage portion 7a in plan view, the first wiring film 4A and the infrared reflection film 6 are insulated. Infrared rays that pass through the film 2 and pass into the storage portion 7a can be blocked by the entire upper portion of the storage portion 7a, and the case 7 can be further prevented from being heated.

Further, since the bottom surface reflecting film 9 that reflects infrared rays is formed on the bottom surface facing the insulating film 2 in the housing 7, the radiant heat radiated from the bottom surface in the housing 7 is directly reflected by the bottom surface reflecting film 9. The influence on the opposing insulating film 2 and heat sensitive elements 3A and 3B can be further suppressed by reflecting and blocking.
In addition, since the housing | casing 7 is formed with resin, it can manufacture cheaply compared with the case of a metal.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, the first heat-sensitive element detects heat conducted from the insulating film that directly absorbs infrared rays. However, the first heat-sensitive element directly absorbs infrared rays on the insulating film immediately above the first heat-sensitive element. A film may be formed. In this case, the infrared absorption effect in the first thermal element is further improved, and a better temperature difference between the first thermal element and the second thermal element can be obtained. That is, the infrared absorption film absorbs infrared rays due to radiation from the object to be measured, and the temperature of the first thermosensitive element immediately below is obtained by heat conduction through the insulating film from the infrared absorption film that absorbs infrared rays and generates heat. May be changed.

This infrared absorbing film is formed of a material having an infrared absorption rate higher than that of the insulating film. For example, a film containing an infrared absorbing material such as carbon black or an infrared absorbing glass film (borosilicate containing 71% silicon dioxide). A material formed of a glass film or the like can be used. In particular, the infrared absorbing film is preferably an antimony-doped tin oxide (ATO) film. This ATO film has better infrared absorption and light resistance than carbon black or the like. In addition, since the ATO film is cured with ultraviolet rays, it has a high adhesive strength and is less likely to be peeled off than carbon black or the like.
In addition, it is preferable to form this infrared rays absorption film so that this may be covered with a larger size than a 1st thermal element. Moreover, when providing an infrared absorption film, it is necessary to set an area and a shape including each wiring film so as to be approximately equal to the heat capacity on the infrared reflection film side.

Moreover, although the 1st thermal element and the 2nd thermal element of a chip | tip thermistor are employ | adopted, you may employ | adopt the 1st thermal element and the 2nd thermal element which were formed with the thin film thermistor.
As the thermal element, a thin film thermistor or a chip thermistor is used as described above, but a pyroelectric element or the like can be used in addition to the thermistor.

  Moreover, in the housing | casing of the said embodiment, although the one storage part which accommodates a 1st thermosensitive element and a 2nd thermosensitive element is provided in the inside, a partition wall is provided inside a housing | casing, and a 1st thermosensitive element is provided. In addition, a pair of storage portions that individually store the second thermosensitive elements may be provided. Moreover, although the inside of the accommodating part is a space with air having a lower thermal conductivity than the insulating film, it may be filled with a foamed resin having a lower thermal conductivity than the insulating film.

  Furthermore, in the above embodiment, the area of the first wiring film is increased and the second wiring film is formed in a linear shape. However, the area of the second wiring film may be set to be somewhat large. In this case, since the heat capacity on the infrared reflective film side changes, it is necessary to consider changes in the ambient temperature, and each wiring film and infrared reflective film have the same heat capacity as much as possible on the reflective side and the absorption side. It is necessary to set the shape and area.

  DESCRIPTION OF SYMBOLS 1 ... Infrared sensor, 2 ... Insulating film, 3A ... 1st thermal element, 3B ... 2nd thermal element, 4A, 104A ... 1st wiring film, 4B ... 2nd wiring film, 6 ... Infrared reflective film , 7 ... Housing, 7a ... Storage part, 9 ... Bottom reflective film

Claims (4)

An insulating film;
A first thermal element and a second thermal element provided on one surface of the insulating film so as to be spaced apart from each other;
A conductive first wiring film formed on one surface of the insulating film and connected to the first thermal element; and a conductive second wiring film connected to the second thermal element;
An infrared reflecting film provided on the other surface of the insulating film facing the second thermosensitive element;
A housing that is fixed to one surface of the insulating film to support the insulating film and that houses the first and second heat sensitive elements in a housing portion;
The first wiring layer is, the conjunction is opposed to the housing bottom, is formed in a larger area than said second wiring film arranged to around the first heat sensitive element, the insulation An infrared sensor characterized in that it blocks infrared rays that are transmitted through a conductive film and irradiates the casing, and also blocks radiant heat emitted from the casing . The infrared sensor according to claim 1,
The infrared sensor, wherein the first wiring film and the infrared reflective film have a shape that covers an upper portion of the storage portion in plan view. The infrared sensor according to claim 1 or 2,
An infrared sensor, wherein a bottom surface reflecting film that reflects infrared rays is formed on a bottom surface facing the insulating film in the housing. In the infrared sensor according to any one of claims 1 to 3,
An infrared sensor, wherein the casing is made of resin.

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