JP2012068115A - Infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared sensor which achieves a large difference in temperature between a heat sensitive element for infrared detection and a heat sensitive element for temperature compensation, and which has a structure that can be downsized and realized at low cost.SOLUTION: An infrared sensor includes: an insulation film 2; a first heat sensitive element 3A and a second heat sensitive element 3B which are provided to be away from each other on one surface of the insulation film 2; multiple pairs of conductive wiring films 4 which are formed on such one surface of the insulation film 2, and which are connected to the first heat sensitive element 3A and the second heat sensitive element 3B separately; a light receiving area 5A which is provided on another surface of the insulation film 2 so as to face the first heat sensitive element 3A; and an infrared reflecting film 6 which is provided on such another surface of the insulation film 2 so as to face the second heat sensitive element 3B. The infrared reflecting film 6 is formed so as to cover a periphery of the light receiving area 5A.

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. An infrared sensor including a temperature-compensating thermosensitive element that detects the temperature of the holder is proposed. In this infrared sensor, an infrared absorption film is formed on the inner side surface of the light guide section, and an infrared absorption material such as carbon black is included in the resin film to enhance infrared absorption. A thin film thermistor is used for the infrared detecting thermal element and the temperature compensating thermal element.

  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.

JP 2002-156284 A (paragraph number 0026, FIG. 2) JP-A-7-260579 (Claims, FIG. 2)

The following problems remain in the conventional technology.
That is, in the 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 employed. The contained resin film has a high thermal conductivity, 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. Furthermore, in the case of a pine needle type or chip type thermistor, spot measurement is performed, and there is a disadvantage that a measurement error occurs when an in-plane distribution of temperature occurs in the resin film.

  The present invention has been made in view of the above-described problems, and can provide a high temperature difference between the thermal sensing elements for infrared detection and temperature compensation, and can be downsized, and has an inexpensive structure. An object is to provide a sensor.

  The present invention employs the following configuration in order to solve the above problems. That is, the infrared sensor of the present 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 one of the insulating films. A plurality of pairs of conductive wiring films formed on a surface and separately connected to the first thermal element and the second thermal element; and the other of the insulating films facing the first thermal element A light receiving region provided on the surface, and an infrared reflecting film provided on the other surface of the insulating film so as to face the second heat sensitive element, the infrared reflecting film surrounding the light receiving region Is also formed to cover.

In this infrared sensor, the light receiving region provided on the other surface of the insulating film facing the first heat sensitive element, and the infrared light provided on the other surface of the insulating film facing the second heat sensitive element. The first heat-sensitive element and the second heat-sensitive element on the thin insulating film having low thermal conductivity due to partial infrared absorption by the light-receiving region and partial infrared reflection by the infrared reflection film. A good temperature difference from the thermal element 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, heat by infrared absorption can be conducted only to the portion directly above the first thermal element of the insulating film by the light receiving region. In addition, since the area of the light receiving region can be set arbitrarily, 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 light receiving region and the infrared reflecting film are provided on the insulating film, the medium that conducts heat between the light receiving region and the infrared reflecting film is only the insulating film other than air, and the conducting cross-sectional area is conducted. Becomes smaller. 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 on the low thermal conductive insulating film is suppressed are respectively insulative between the light receiving region and the infrared reflective film. It has a structure for measuring the partial temperature of the 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.

Further, since the thermal coupling between the first thermal element and the second thermal element is low, it is possible to arrange them close to each other, and the overall size can be reduced. Further, since the absorption of infrared rays is prevented by the infrared reflection film rather than the light shielding structure by the frame or case, it can be manufactured at low cost.
In addition, even if the infrared reflective film is made of a conductive material, the insulation with the second thermal element installed with the insulating film interposed therebetween is ensured, so that the efficiency can be improved regardless of the insulation of the film. A good material can be selected.
Furthermore, since a thin wiring film having low thermal conductivity is provided on the insulating film, it is possible to prevent thermal coupling between the lead wire and the thermistor with other portions due to space conduction as in the prior art.

In addition, since the infrared reflective film is formed so as to cover the periphery of the light receiving region, the temperature gradient due to air convection between the first thermal element side and the second thermal element side is reduced, and the two thermal elements. It becomes possible to make the response speed of the same.
For example, when an infrared reflective film is formed only in a region facing the second heat sensitive element, when air flows from the second heat sensitive element side by convection of the surrounding air, it is located above the second heat sensitive element. The infrared reflective film is cooled and the temperature of the insulating film changes locally. On the other hand, in the infrared sensor of the present invention, since the infrared reflecting film is formed so as to cover the periphery of the light receiving region facing the first thermal element, the region on the second thermal element side is cooled by the air flow. However, the temperature around the light receiving region also decreases due to the thermal conductivity of the infrared reflecting film, and the difference in temperature hardly occurs as a whole, and it is difficult to be affected by the convection of the surrounding air. In addition, since the light reception area | region above the 1st thermal element is not covered with an infrared reflective film, it does not prevent the infrared light reception from a measuring object.

In the infrared sensor of the present invention, the area of the infrared reflection film and the area of the light receiving region are set to be the same.
That is, in this infrared sensor, since the area of the infrared reflecting film and the area of the light receiving region are set to be the same, the light receiving areas of the infrared reflecting film and the light receiving region are the same, and the infrared reflecting film and the light receiving region are the same. By receiving the same radiant energy, more accurate detection becomes possible.

In the infrared sensor of the present invention, the infrared reflective film covers all portions other than the light receiving region on the other surface of the insulating film.
That is, in this infrared sensor, since the infrared reflecting film covers all the portions other than the light receiving area on the other surface of the insulating film, the insulating film is not directly exposed on the other surface, and the insulating film other than the light receiving area is insulated. Infrared absorption by the heat-sensitive film itself can be suppressed as much as possible, and the influence on the first and second heat sensitive elements due to heat conduction from the surroundings can be reduced.

The infrared sensor of the present invention is characterized in that an infrared absorption film is provided in the light receiving region.
That is, in this infrared sensor, since the infrared absorption film is provided in the light receiving area, a higher infrared absorption effect can be obtained than in the case of directly receiving light with the insulating film exposed in the light receiving area, and the first thermal sensitivity. An even better temperature difference between the element and the second thermosensitive element can be obtained.

The present invention has the following effects.
That is, according to the infrared sensor according to the present invention, since the infrared reflective film provided on the other surface of the insulating film is provided so as to face the second thermal element, the first thermal element and the second thermal element are provided. A good temperature difference from the thermosensitive element can be obtained, high sensitivity can be achieved, and the device can be made small and inexpensive. Furthermore, since the infrared reflective film is formed so as to cover the periphery of the light receiving region, the temperature gradient due to air convection between the first heat sensitive element side and the second heat sensitive element side is reduced, and the two heat sensitive elements are It becomes possible to make the response speed equal. Therefore, it is possible to reduce the detection error by suppressing the influence of air convection.

It is a perspective view which shows 1st Embodiment of the infrared sensor which concerns on this invention. In 1st Embodiment, it is a front view which shows an infrared sensor. In 1st Embodiment, it is a top view which shows an infrared sensor. It is a top view which shows 2nd Embodiment of the infrared sensor which concerns on this invention.

  Hereinafter, a first embodiment of an infrared sensor according to the present invention will be described with reference to FIGS. 1 to 3. 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 3, 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 plurality of pairs of conductive elements patterned on one surface of the insulating film 2 with copper foil or the like and separately connected to the first thermal element 3A and the second thermal element 3B The wiring film 4, the light receiving region 5A provided on the other surface (upper surface) of the insulating film 2 so as to face the first heat sensitive element 3A, and the insulating film 2 facing the second heat sensitive element 3B. And an infrared reflecting film 6 provided on the other surface of the optical fiber.

In addition, an infrared absorption film 5 is formed in the light receiving region 5A. That is, the infrared absorption film 5 is disposed immediately above the first heat sensitive element 3A, and the infrared reflection film 6 is disposed directly above the second heat sensitive element 3B.
The insulating film 2 is formed of an infrared transmissive film. In the present embodiment, the insulating film 2 is formed of a polyimide resin sheet.

  The first heat sensitive element 3A and the second heat sensitive element 3B are chip thermistors in which terminal electrodes 3a are formed at both ends. 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 with the terminal electrodes 3a bonded to the wiring film 4.

  The infrared absorption film 5 is formed of a material having an infrared absorption rate higher than that of the insulating film 2. For example, a film or an infrared absorption glass film containing an infrared absorption material such as carbon black or antimony-doped tin oxide (ATO). (Such as a silicate glass film containing 71% silicon dioxide). That is, the infrared absorption film 5 absorbs infrared rays due to radiation from the measurement object. The temperature of the first thermosensitive element 3A immediately below is changed by heat conduction through the insulating film 2 from the infrared absorbing film 5 that absorbs infrared rays and generates heat. The infrared absorption film 5 is formed so as to cover a larger size than the first thermal element 3A.

  The infrared reflection film 6 is formed of a material having an infrared emissivity higher than that of the insulating film 2, and is formed of, for example, a mirror-deposited aluminum vapor deposition film or an aluminum foil. The infrared reflective film 6 is formed so as to cover a larger size than the second thermal element 3B. In the present embodiment, as shown in FIG. 3, the infrared reflective film 6 (hatching in FIG. 3) is formed. Part) also covers the periphery of the light receiving region 5A. That is, the infrared reflection film 6 covers all the portions other than the rectangular light receiving region 5 </ b> A (infrared absorption film 5) on the other surface of the insulating film 2.

  As described above, the infrared sensor 1 of the present embodiment includes the light receiving region 5A (infrared absorbing film 5) provided on the other surface of the insulating film 2 so as to face the first heat sensitive element 3A, and the second heat sensitive element. And the infrared reflection film 6 provided on the other surface of the insulating film 2 so as to face 3B, so that partial infrared absorption by the light receiving region 5A and partial infrared reflection by the infrared reflection film 6 Thus, a good temperature difference between the first thermal element 3A and the second thermal element 3B can be obtained on the thin insulating film 2 having low thermal conductivity.

  That is, even in the low thermal conductive insulating film 2 in which the film does not contain an infrared absorbing material or the like, as shown in FIG. 2, the first heat sensitive element 3A of the insulating film 2 is formed by the infrared absorbing film 5 in the light receiving region 5A. It is possible to conduct heat due to infrared absorption only to the portion directly above. In particular, since the heat of the infrared absorption film 5 is conducted across the thin insulating film 2, there is no deterioration in sensitivity and high responsiveness is achieved. In addition, since the area of the light receiving region 5A can be set arbitrarily, 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.

In addition, the infrared reflection film 6 can reflect the infrared rays directly above the second heat sensitive element 3B of the insulating film 2 to prevent its absorption.
Since the infrared absorption film 5 and the infrared reflection film 6 are formed on the insulating film 2, the medium that conducts heat between the infrared absorption film 5 and the infrared reflection film 6 is a film other than air. Becomes only the insulating film 2 between the two facing each other, and the cross-sectional area to be conducted 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 3A and the second heat sensitive element 3B, on which the influence of heat on the insulating film 2 with low thermal conductivity is suppressed, are directly below the light receiving region 5A (infrared absorbing film 5). And a structure for measuring a partial temperature of the insulating film 2 immediately below the infrared reflective film 6. Therefore, it is possible to obtain a good temperature difference between the first thermal element 3A for infrared detection and the second thermal element 3B for temperature compensation, thereby achieving high sensitivity.

  Further, since the thermal coupling between the first thermal element 3A and the second thermal element 3B is low, they can be arranged close to each other, and the overall size can be reduced. Furthermore, since the absorption of infrared rays is prevented by the infrared reflection film 6 rather than the light shielding structure by the frame or case, it can be manufactured at low cost.

Moreover, even if the infrared absorption film 5 and the infrared reflection film 6 are made of a conductive material, insulation with the first and second thermal elements 3A and 3B installed with the insulating film 2 interposed therebetween is ensured. Therefore, an efficient material can be selected regardless of the insulating properties of the film.
Further, since the wiring film 4 that is thin and has low thermal conductivity is provided on the insulating film 2, it is possible to prevent thermal coupling between the lead wire and the thermistor with other portions due to space conduction as in the prior art. .

Further, since the infrared reflective film 6 is formed so as to cover the periphery of the light receiving region 5A, the temperature gradient due to air convection between the first thermal element 3A side and the second thermal element 3B side is reduced, It becomes possible to make the response speeds of the two thermosensitive elements equal.
For example, when the infrared reflective film 6 is formed only in a region facing the second thermal element 3B, when air flows from the second thermal element 3B side by convection of the surrounding air, the second thermal element The infrared reflective film 6 above 3B is cooled and the temperature of the insulating film 2 is locally changed.

  On the other hand, in the infrared sensor 21 of the present embodiment, the infrared reflecting film 6 is formed so as to cover the periphery of the light receiving region 5A facing the first thermal element 3A, as shown in FIGS. Even if the region on the second thermosensitive element 3B side is cooled by the air flow, the temperature around the light receiving region 5A is lowered due to the thermal conductivity of the infrared reflecting film 6, and the temperature difference is hardly generated as a whole. Less affected by air convection.

In addition, since the infrared reflection film 6 covers all the portions other than the light receiving region 5A on the other surface of the insulating film 2, the insulating film 2 is not directly exposed on the other surface, and the insulating portions other than the light receiving region 5A are insulated. Infrared absorption by the heat-sensitive film 2 itself can be suppressed as much as possible, and the influence on the first heat sensitive element 3A and the second heat sensitive element 3B due to heat conduction from the surroundings can be reduced.
Further, since the infrared absorption film 5 is provided in the light receiving region 5A, a higher infrared absorption effect can be obtained than in the case where light is directly received by the insulating film 2 exposed in the light receiving region 5A. A better temperature difference between 3A and the second thermosensitive element 3B can be obtained.

  Next, a second embodiment of the infrared sensor according to the present invention will be described below with reference to FIG. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that, in the first embodiment, the area of the light receiving region 5A (infrared absorbing film 5) is smaller than the area of the infrared reflecting film 6, whereas the second embodiment. The infrared sensor 21 is different in that the area of the infrared reflection film 6 and the area of the light receiving region 5A are set to be the same as shown in FIG. That is, in the second embodiment, the area of the light receiving region 5A is larger than that of the first embodiment, and the light receiving region 5A is formed so as to spread toward the second heat sensitive element 3B from the center of the insulating film 2.

  As described above, in the infrared sensor 21 of the second embodiment, since the area of the infrared reflection film 6 and the area of the light receiving region 5A are set to be the same, the light receiving areas of the infrared reflection film 6 and the light receiving region 5A are the same. Thus, the infrared reflection film 6 and the light receiving region 5A receive the same radiant energy, thereby enabling detection with higher accuracy.

  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 each of the above embodiments, the first and second thermosensitive elements of the chip thermistor are employed, but the first and second thermosensitive elements formed by the thin film thermistor are employed. It doesn't matter.
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.

  In addition, a housing fixed to one surface of the insulating film and supporting the insulating film is provided, and the first heat sensitive element and the second heat sensitive element are individually housed in the housing, and are insulated. You may provide the 1st accommodating part and the 2nd accommodating part which are covered with the air or foaming resin whose heat conductivity is lower than a film.

  Furthermore, it is preferable to form an infrared absorption film in the light receiving region above the first heat sensitive element as in the above embodiments, but an infrared reflective film is formed above the second heat sensitive element and around the light receiving region. If so, the infrared absorption film may not be formed in the light receiving region above the first thermal element. That is, the light receiving region may be a surface where the insulating film is directly exposed.

  DESCRIPTION OF SYMBOLS 1,21 ... Infrared sensor, 2 ... Insulating film, 3A ... 1st thermosensitive element, 3B ... 2nd thermosensitive element, 4 ... Wiring film, 5 ... Infrared absorption film, 5A ... Light receiving area, 6 ... Infrared 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 plurality of pairs of conductive wiring films formed on one surface of the insulating film and separately connected to the first thermal element and the second thermal element;
A light receiving region provided on the other surface of the insulating film facing the first thermosensitive element;
An infrared reflection film provided on the other surface of the insulating film facing the second thermosensitive element,
The infrared sensor, wherein the infrared reflecting film is formed so as to cover the periphery of the light receiving region. The infrared sensor according to claim 1,
An infrared sensor, wherein an area of the infrared reflecting film and an area of the light receiving region are set to be the same. The infrared sensor according to claim 1 or 2,
The infrared sensor, wherein the infrared reflective film covers all portions other than the light receiving region on the other surface of the insulating film. In the infrared sensor according to any one of claims 1 to 3,
An infrared sensor, wherein an infrared absorption film is provided in the light receiving region.

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