JP2017181031A - Infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared sensor capable of performing highly accurate measurement while suppressing transmission of heat from a light guide path member.SOLUTION: An infrared sensor comprises a substrate 2, a sensor body 3 which is a thermosensitive part provided on a top face of the substrate, and a cylindrical light guide path member 4 which has an opening part at the upper side of the sensor body and covers at least the periphery of a light receiving face of the sensor body. On the inner face of the light guide path member which is formed from plate-like resin, a metal film 5 having higher infrared reflectance than that of the resin is formed apart from the sensor body 3 and the substrate 2.SELECTED DRAWING: Figure 1

Description

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

In general, in order to measure the temperature of an object to be measured such as a fixing roller used in an image forming apparatus such as a copying machine or a printer, an infrared sensor is disposed opposite the object to be measured and receives the radiant heat to measure the temperature. Is installed.
For example, in Patent Document 1, a resin film installed on a holder, a thermal element for detecting infrared rays that is provided on the resin film and detects infrared rays through a light guide portion of the holder, and provided in a light-shielded state on the resin film. An infrared temperature sensor including a temperature-compensating thermosensitive element for detecting the temperature of the holder is proposed.

Patent Document 2 proposes an infrared sensor device including an infrared sensor element and a field-of-view restriction unit that has an opening and covers a part of the field of view of the infrared sensor element.
Furthermore, cited document 3 describes an infrared sensor device including a cylindrical light guide member formed of stainless steel or the like.
In these infrared sensors, a light guide member is installed as a light guide unit or a field limiting unit in order to limit the incidence of radiant heat from the outside with a constant viewing angle. Moreover, in the infrared sensor of patent document 2, the metal reflective film is formed in the surface of the visual field restriction | limiting part of resin.

JP 2002-156284 A JP 2014-81204 A JP 2014-157045 A

The following problems remain in the conventional technology.
In the conventional infrared sensor such as Cited Document 1, the light guide member itself also absorbs infrared rays to generate heat, so that heat is transmitted from the light guide member to the heat sensitive part or the substrate and affects the measurement by the heat sensitive part. There was an inconvenience. Further, in Cited Document 2, it is possible to suppress infrared rays from being reflected by the metal reflection film and absorbed by the visual field limiting part, but the visual field limiting part formed by opening a hole in a thick member has a large heat capacity. The heat was stored and the heat sensitive part was still affected. Further, in the above cited document, since the metal light guide member or reflective film having high thermal conductivity is in contact with the heat sensitive part or the substrate, the metal light guide member or reflective film is directly between the heat sensitive part or the substrate. There was a possibility that heat would be transmitted and affect the non-contact temperature measurement.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an infrared sensor capable of measuring with high accuracy by suppressing generation of heat of a light guide member due to infrared absorption.

  The present invention employs the following configuration in order to solve the above problems. That is, an infrared sensor according to a first aspect of the present invention includes a substrate, a sensor main body that is a heat-sensitive portion provided on the upper surface of the substrate, and an opening above the sensor main body. A cylindrical light guide member covering the periphery of the sensor, the light guide member is formed of a plate-like resin, and a metal film having an infrared reflectance higher than that of the resin is formed on the inner surface of the sensor body and the substrate. It is characterized by being formed apart.

  That is, in this infrared sensor, the light guide member is formed of a plate-like resin, and a metal film having an infrared reflectance higher than that of the resin is formed on the inner surface thereof so as to be separated from the sensor body and the substrate. It is possible to suppress generation of heat in the light guide member without being absorbed by the light guide member due to the infrared rays incident on the optical path member being reflected by the metal film on the inner surface. Moreover, since the light guide member is made of a thin plate-like resin, the heat capacity of the light guide member can be reduced, and the influence of the heat of the light guide member on the sensor body can be reduced. Furthermore, since the metal film is not in direct contact with the sensor body and the substrate, heat is not directly transferred between the metal film, the sensor body and the substrate, and the influence of the heat on the sensor body via the metal film is suppressed. can do.

The infrared sensor according to a second invention is characterized in that, in the first invention, the metal film is also formed on an outer surface of the light guide member.
That is, in this infrared sensor, since the metal film is also formed on the outer surface of the light guide member, the infrared light incident on the outer surface of the light guide member is also reflected by the metal film to prevent infrared absorption even on the outside. be able to.

An infrared sensor according to a third invention is the infrared sensor according to the first or second invention, wherein an inner surface of the light guide member is a flat surface and at least a part of the resin of the light guide member is porous. It is characterized by.
That is, in this infrared sensor, since the inner surface of the light guide member is a flat surface and at least a part of the resin of the light guide member is porous, the inner surface of the light guide member is flat and has a high infrared reflectance. A metal film is obtained, and at least a part of the resin is made porous, so that the heat insulation is improved and the heat capacity is reduced.

An infrared sensor according to a fourth invention is the infrared sensor according to any one of the first to third inventions, wherein the light guide member is disposed on the substrate with at least one gap between the light guide member and the substrate. It is characterized by.
That is, in this infrared sensor, since the light guide member is disposed on the substrate with at least one gap between the light guide member and the substrate, the light guide member is partially separated from the substrate by the gap. Therefore, the heat of the light guide member becomes difficult to be transmitted to the substrate, and the measurement by the sensor body which is the heat sensitive part is hardly affected.

The present invention has the following effects.
That is, according to the infrared sensor of the present invention, the light guide member is formed of a plate-like resin, and a metal film having an infrared reflectance higher than that of the resin is formed on the inner surface thereof so as to be separated from the sensor body and the substrate. Therefore, the infrared ray is reflected by the metal film on the inner surface, the heat capacity of the light guide member is small, and the metal film, the sensor main body and the substrate are not in direct contact, so that the sensor main body by the light guide member and the metal film The thermal influence on can be reduced.

It is sectional drawing which shows 1st Embodiment of the infrared sensor which concerns on this invention. In 1st Embodiment, it is a side view which shows an infrared sensor. In 1st Embodiment, it is a top view which shows an infrared sensor. In 1st Embodiment, it is the side view (a) and front view (b) which show a light guide way member. In 1st Embodiment, it is a perspective view which shows an infrared sensor main body. In 1st Embodiment, it is sectional drawing which shows an infrared sensor main body. In 1st Embodiment, it is a back view which shows the insulating film in which the wiring film was formed. It is sectional drawing which shows 2nd Embodiment of the infrared sensor which concerns on this invention. It is an expanded sectional view of the important section showing a 3rd embodiment of an infrared sensor concerning the present invention.

  Hereinafter, a first embodiment of an infrared sensor according to 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 3, the infrared sensor 1 according to the present embodiment includes a substrate 2, a sensor body 3 that is a heat sensitive part provided on the upper surface of the substrate 2, and an opening above the sensor body 3. A cylindrical light guide member 4 that covers at least the periphery of the light receiving surface 3a of the sensor body 3 is provided.
The light guide member 4 is formed of a plate-like resin, and a metal film 5 having an infrared reflectance higher than that of the resin is formed on the inner surface thereof so as to be separated from the sensor body 3 and the substrate 2.

The light guide member 4 is installed on the substrate 2 with at least one gap 4 a between the light guide member 4 and the substrate 2.
The metal film 5 is formed above the gap 4 a on the inner surface of the light guide member 4.

The substrate 2 has a plurality of mounting holes 2 a for the light guide member 4.
The light guide member 4 has a plurality of fixing claw portions 4b fitted into the mounting holes 2a in a penetrating state and a plurality of support convex portions 4c whose lower ends are in contact with each other on the substrate 2. Yes. The fixing claw portion 4b and the support convex portion 4c are formed so as to protrude downward from the lower portion of the light guide member 4.
The gap 4a is formed between the fixing claw 4b and the support protrusion 4c and between the support protrusions 4c. That is, the concave portion 4 a ′ formed between the fixing claw portion 4 b and the support convex portion 4 c and between the support convex portions 4 c becomes the gap portion 4 a between the substrate 2.

As described above, a pair of fixing claw portions 4b are formed in the lower portions of both side surfaces of the light guide member 4, and two attachment holes 2a corresponding to the two fixing claw portions 4b are formed in the substrate 2. Is formed.
In FIG. 3, for easy understanding, each support convex portion 4 c is surrounded by a two-dot chain line.

The pair of fixing claws 4b have elasticity, and when inserted into the mounting hole 2a, they are bent inward and inserted into the mounting hole 2a. Thus, the claw portion is locked to the back surface of the substrate 2.
In addition, the support protrusions 4 c are formed on both sides of the pair of fixing claws 4 b at the lower portions of the pair of side surfaces facing the light guide member 4, and on the front and back portions of the light guide member 4. Each one is formed. That is, six support convex portions 4 c are formed in the lower portion of the light guide member 4.

The light guide member 4 has a rectangular tube shape, and is integrally formed of resin together with the fixing claw portion 4b and the support convex portion 4c. Examples of the resin constituting the light guide member 4 include polyphenylene sulfide, polyether ether ketone, polycarbonate, polyamide, fluororesin, phenol resin, polyester resin, epoxy resin, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, acrylic resin, and polyvinyl alcohol. Etc. are adopted.
The metal film 5 can be a metal thin film such as Au, Ag, Al, or Cu.

  As shown in FIGS. 5 to 7, the sensor body 3 includes an insulating film 10 having a light receiving surface 3 a on the upper surface, a first thermal element 8 </ b> A provided on the lower surface of the insulating film 10 and spaced apart from each other. The second thermal element 8B and the conductive first wiring film 11A formed on the lower surface of the insulating film 10 and connected to the first thermal element 8A and the conductive element connected to the second thermal element 8B. And a second wiring film 11B.

  The sensor body 2 includes a resin-made terminal support 12 disposed on the lower surface side of the insulating film 10 and a plurality of mountings provided on the terminal support 12 and having a lower portion disposed below the terminal support 12. Terminal 13 is provided.

In addition, the light receiving surface 3a is provided in the region on the first thermal element 8A side of the upper surface of the insulating film 10, and the region on the second thermal element 8B side is a region that shields infrared rays. .
In the region on the second thermal element 8B side, the infrared reflecting film 14 is patterned to shield infrared rays, and a region that shields infrared rays is provided.

That is, the infrared reflective film 14 is provided on the upper surface of the insulating film 10 so as to face the second thermal element 8B. The infrared reflection film 14 is formed in a rectangular shape in a region on the second thermal element 8B side on the upper surface of the insulating film 10.
The infrared reflecting film 14 is formed of a material having an infrared reflectance higher than that of the insulating film 10 and is formed by applying a gold plating film on a copper foil. 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 reflection film 14 is formed to cover the second thermal element 8B with a size larger than that of the second thermal element 8B.

  The first thermal element 8A and the second thermal element 8B are chip thermistors in which terminal portions are formed at both ends. As the thermistor, there are thermistors of NTC type, PTC type, CTR type and the like. In the present embodiment, for example, NTC type thermistors are employed as the first thermal element 8A and the second thermal element 8B. This thermistor is formed of a thermistor material such as a Mn—Co—Cu-based material or a Mn—Co—Fe-based material.

Adhesive electrodes 15A and 15B formed on the insulating film 10 are connected to one end of each of the first wiring film 11A and the second wiring film 11B, and the insulating film 10 is connected to the other end. The terminal electrodes 16A and 16B formed in the are connected.
The terminal portions of the corresponding first thermal element 8A and second thermal element 8B are bonded to the adhesive electrodes 15A and 15B with a conductive adhesive such as solder.

  The insulating film 10 is formed of a polyimide resin sheet in a rectangular shape, and the infrared reflecting film 14, the first wiring film 11A, and the second wiring film 11B are formed of copper foil. That is, these are formed by a double-sided flexible substrate in which the surface of a polyimide substrate used as the insulating film 10 is patterned with a copper foil used as the infrared reflecting film 14, the first wiring film 11A, and the second wiring film 11B. It was produced.

The mounting terminal 13 is made of, for example, a tin-plated copper alloy. The mounting terminal 13 extends to the upper portion of the terminal support 12 and is connected to the first terminal electrode 16A and the second terminal electrode 16B in the corresponding first wiring film 11A and second wiring film 11B. ing.
Further, the lower portion 13 a of the mounting terminal 13 is provided so as to protrude downward from the lower surface of the terminal support 12. That is, the mounting terminal 13 extends vertically, and the lower portion 13a protrudes downward from the lower surface of the terminal support 12, and the lower portion 13a bends and protrudes laterally. It is formed in a letter shape.
The mounting terminals 13 are respectively arranged in the vicinity of the four corners of the terminal support 12 and are incorporated into the terminal support 12 by insert molding or fitting.

  The terminal support 12 is made of a resin such as PPS (polyphenylene sulfide resin) and is formed in a frame shape along at least the outer edge of the insulating film 10. That is, the terminal support 12 includes an outer frame portion along the outer edge portion of the insulating film 10 and an intermediate frame portion that crosses an intermediate portion between the first thermal element 8A and the second thermal element 8B. ing.

The substrate 2 is a printed circuit board (PCB), for example, and is formed in a rectangular shape.
The substrate 2 includes a plurality of wiring patterns 2b connected to the sensor body 3 and patterned with copper foil or the like on the upper surface thereof. One end of each wiring pattern 2 b is connected to each mounting terminal 13 of the sensor body 3, and the other end is arranged on the end side of the substrate 2. That is, the wiring pattern 2b is electrically connected to the thermal elements 8A and 8B via the mounting terminals 13, the wiring film 11A, and the wiring film 11B. These wiring patterns 2b are arranged through the gaps 4a. That is, the wiring pattern 2b is wired on the substrate 2 over the inside and outside of the light guide member 4 through the gap 4a.

About the infrared sensor 1 of this embodiment, it simulated about the relative sensitivity according to the material of the light guide member 4 as a measurement object (black body) 180 degreeC and environmental temperature 50 degreeC.
The relative sensitivity (Fs) is a relative value (Fs ratio) when the relative sensitivity is 1.000 in the case of a light guide member made of only stainless steel having a thickness of 0.2 mm. A larger relative sensitivity means that the temperature difference between the first thermal element 8A on the detection side and the second thermal element 8B on the compensation side is larger and the sensitivity is higher.

  First, in the case of a light guide member composed only of a resin (PPS) having a thickness of 0.2 mm, the relative sensitivity was 1.022. Furthermore, in this embodiment, when an aluminum metal film 5 with a thickness of 50 nm is formed on the inner surface of a light guide member 4 formed in a cylindrical shape with a resin (PPS) with a thickness of 0.2 mm, the relative sensitivity is 1.286. And greatly improved.

  Thus, in the infrared sensor 1 of the present embodiment, the light guide member 4 is formed of a plate-shaped resin, and the metal film 5 having an infrared reflectance higher than that of the resin is separated from the sensor body 3 and the substrate 2 on the inner surface thereof. Therefore, the infrared light incident in the light guide member 4 is reflected by the metal film 5 on the inner surface and is not absorbed by the light guide member 4, and heat is generated in the light guide member 4. Can be suppressed.

  Moreover, since the light guide member 4 is made of a thin plate-like resin, the heat capacity of the light guide member 4 can be reduced, and the influence of the heat of the light guide member 4 on the sensor body 3 can be reduced. Further, since the metal film 5 is not in direct contact with the sensor body 3 and the substrate 2, heat is not directly transferred between the metal film 5, the sensor body 3, and the substrate 2, and the sensor body via the metal film 5. The influence of heat on 3 can be suppressed.

  Further, since the light guide member 4 is disposed on the substrate 2 with at least one gap 4a between the light guide member 4 and the substrate 2, the light guide member 4 is partially separated from the substrate 2 by the gap 4a. By separating, it becomes difficult for the heat of the light guide member 4 to be transmitted to the substrate 2, and it is difficult to affect the measurement by the sensor body 3 which is a heat sensitive part.

  Next, 2nd and 3rd embodiment of the infrared sensor which concerns on this invention is described below with reference to FIG.8 and FIG.9. In the following description of each embodiment, the same constituent elements 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 the metal film 5 is formed only on the inner surface of the light guide member 4 in the first embodiment, whereas the infrared sensor 21 of the second embodiment is different. As shown in FIG. 8, the metal film 5 is also formed on the outer surface of the light guide member 24.
That is, in the second embodiment, the metal film 5 is formed on both the inner surface and the outer surface of the light guide member 24, and any metal film 5 is formed away from the substrate 2.

  As described above, in the infrared sensor 21 according to the second embodiment, the metal film 5 is also formed on the outer surface of the light guide member 24. Therefore, the infrared rays incident on the outer surface of the light guide member 24 are also reflected by the metal film 5. Thus, absorption of infrared rays can be prevented even on the outside.

Next, the difference between the third embodiment and the first embodiment is that, in the first embodiment, the light guide member 4 is formed of a resin having a dense plate shape, but the infrared rays of the third embodiment are different. In the sensor, as shown in FIG. 9, the inner surface of the light guide member 34 is a flat surface, and at least a part of the resin of the light guide member 34 is porous.
That is, in the third embodiment, the inner side of the light guide member 34 is a resin dense layer 34 a and the outer side is a porous layer 34 b, and the plate-like resin of the light guide member 34 is sandwiched between the metal films 5. It has a sandwich structure.

A metal film 5 is formed on the surface of the dense layer 34a, and the surface of the metal film 5 is a flat and mirror surface.
Thus, in the infrared sensor of the third embodiment, the inner surface of the light guide member 34 is a flat surface and at least a part of the resin of the light guide member 34 is porous. As a result, the metal film 5 which is flat and has a high infrared reflectance is obtained, and at least a part of the resin is made porous, thereby improving heat insulation and reducing heat capacity.

  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-described embodiments, a heat sensitive element of a chip thermistor is employed, but a heat sensitive element formed of a thin film thermistor may be employed.
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 each said embodiment, although the insulating film is provided on the housing | casing installed in the upper surface of the board | substrate, you may install an insulating film directly on the upper surface of a board | substrate, and may provide a sensor main body.

  DESCRIPTION OF SYMBOLS 1,21 ... Infrared sensor, 2 ... Board | substrate, 3 ... Sensor main body, 4, 24, 34 ... Light guide member, 4a ... Gap part, 5 ... Metal film

Claims (4)

A substrate,
A sensor body which is a heat sensitive part provided on the upper surface of the substrate;
A cylindrical light guide member having an opening above the sensor body and covering at least the light receiving surface of the sensor body;
An infrared sensor, wherein the light guide member is formed of a plate-like resin, and a metal film having an infrared reflectance higher than that of the resin is formed on an inner surface thereof so as to be separated from the sensor body and the substrate. . The infrared sensor according to claim 1,
An infrared sensor, wherein the metal film is also formed on an outer surface of the light guide member. The infrared sensor according to claim 1 or 2,
An infrared sensor, wherein an inner surface of the light guide member is a flat surface and at least a part of the resin of the light guide member is porous. In the infrared sensor according to any one of claims 1 to 3,
An infrared sensor, wherein the light guide member is disposed on the substrate with at least one gap between the light guide member and the substrate.

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