JP6530652B2 - Light emitting and receiving device - Google Patents

Description

  The present invention relates to a light emitting and receiving device, and more particularly to a compact and highly accurate light emitting and receiving device.

Conventionally, as a gas concentration measuring device for measuring the concentration of a gas to be measured in the atmosphere, the gas concentration is measured by detecting the amount of absorption utilizing the fact that the wavelength of infrared rays absorbed differs depending on the type of gas. Non-dispersive infrared gas concentration measuring devices are known.
For example, in the gas component detection device described in Patent Document 1, light including infrared rays emitted from the light emitting unit passes through the cell into which the gas to be measured is introduced, and then enters the light receiving unit and enters the light receiving unit. The presence or absence and concentration of the gas to be measured are detected according to the output signal of

International Publication No. 2012/140485

However, when it is necessary to detect the gas concentration more accurately, it is necessary to make the cell larger and to make the light path longer in order to increase the absorption by the gas to be measured.
The present invention has been made in view of such problems, and an object of the present invention is to provide a compact and highly accurate light emitting and receiving device.

In order to solve the above problems, a light emitting and receiving device according to a first aspect of the present invention condenses light incident from a light emitting portion, a light receiving portion, and a focal position that outputs light absorbed by a gas to be detected A first light collecting portion, a first reflecting portion that reflects the light collected by the first light collecting portion, a second reflecting portion that reflects the light reflected by the first reflecting portion, and the second light collecting portion A third reflecting unit that reflects the light reflected by the reflecting unit, a second focusing unit that focuses the light reflected by the third reflecting unit at a focal position, and a signal processing unit that receives the output of the light receiving unit And a sealing unit provided in a space into which the gas to be detected is introduced and integrally sealing the light emitting unit, the light receiving unit, and the signal processing unit , the light emitting unit; The light receiving unit, the first light collecting unit, the second light collecting unit, and the second reflecting unit are one of the light emitting and receiving devices in plan view. Arranged on the side, the first reflecting portion and the third reflecting unit is a planar view, the arranged on the other side of the light receiving and emitting device across the space, the light emitting part of the first condensing section The light receiving unit is disposed at a focal position, the light receiving unit is disposed at a focal position of the second light collecting unit, and the second reflecting unit faces the reflecting surface of the second reflecting unit toward the other side of the light emitting and receiving device. The first reflecting portion and the third reflecting portion are disposed on one side of the light emitting and receiving device with the reflecting surface of the first reflecting portion and the reflecting surface of the third reflecting portion facing each other, The light collected by the first light collecting portion is reflected a plurality of times between the one side and the other side of the light emitting and receiving device by the first reflecting portion, the second reflecting portion, and the third reflecting portion. are, are absorbed to attenuate by the gas to be detected in the space, Mitsunobu after attenuation the light receiving unit has received To based the a light receiving and emitting device that is used in the concentration measurement of a gas to be detected.

  According to the present invention, it is possible to realize a compact and highly accurate light emitting and receiving device.

(A)-(c) is a block diagram for demonstrating Embodiment 1 of the light emitting / receiving apparatus based on this invention. It is a block diagram for demonstrating Embodiment 2 of the light emitting / receiving apparatus based on this invention. It is a block diagram for demonstrating Embodiment 3 of the light emitting / receiving apparatus based on this invention. It is a block diagram for demonstrating Embodiment 4 of the light receiving / emitting device based on this invention. It is a perspective view of the light emitting and receiving apparatus of Embodiment 3 shown in FIG. It is the B-B 'line sectional view of FIG. It is a figure which shows the mounting state of the light emitting / receiving apparatus of Embodiment 1 shown to FIG.1 (a)-(c). (A), (b) is a block diagram for demonstrating the other embodiment of the light emitting / receiving apparatus based on this invention.

Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as the present embodiment) will be described. The following embodiments do not limit the invention according to the claims. Moreover, not all combinations of features described in the embodiments are essential to the solution of the invention.
<Light emitting and receiving device>
The light emitting and receiving device according to the present embodiment includes a light emitting unit, a light receiving unit, a first light collecting unit that collects light incident from a focal position, and a reflection that reflects light collected by the first light collecting unit. And a second light collecting unit for collecting light reflected by the reflecting unit at a focal position, the light emitting unit is disposed at the focal position of the first light collecting unit, and the light receiving unit is the second light collecting unit. It is placed at the focal position.

<Light emitting unit>
In the light emitting and receiving device according to the present embodiment, the light emitting unit is installed at the focal position of the first light collecting unit. Here, the state in which the light emitting unit is installed at the focal position of the first light collecting unit means a state in which a part of the light emitting unit includes the focus of the first light collecting unit described later. The light emitting part is not particularly limited as long as it outputs light including a wavelength absorbed by the gas to be detected. Specific examples include MEMS light sources and LEDs. Among them, from the viewpoint of reducing noise due to light absorption of components other than the gas to be detected, it is preferable to output only light in a wavelength band where absorption of the gas to be detected is large. Specifically, an LED structure may be desirable from the viewpoint that the emission wavelength band can be controlled by the band gap of the active layer. When using a light source of an LED, tuning of the band gap of the material used for the light emitting layer to the absorption wavelength of the gas to be detected enables detection of a specific gas without using an optical filter (for example, a band pass filter) This makes it possible to realize a gas sensor without an optical filter. If a gas sensor without an optical filter can be realized, the structure of the light emitting and receiving device is simplified and the form becomes more preferable.

<Light receiving unit>
In the light emitting and receiving device according to the present embodiment, the light receiving unit is installed at the focal position of the second light collecting unit. Here, the state in which the light receiving unit is installed at the focal position of the second light collecting unit means a state in which a part of the light receiving unit includes the focus of the second light collecting unit described later. The light receiving portion is not particularly limited as long as it has sensitivity to the band of light including the wavelength absorbed by the gas to be detected. For the light receiving portion, a thermal sensor such as a pyroelectric sensor, a thermopile, or a bolometer, a quantum sensor such as a photodiode having a PIN structure, or the like is preferable. The light receiving unit may further include an optical filter having desired optical characteristics along with the gas to be measured. For example, in the case where the gas to be detected is carbon dioxide, the light receiving portion may be provided with a band pass filter capable of filtering out infrared rays in a wavelength range (typically around 4.3 μm) where much infrared absorption by carbon dioxide occurs. Ru.

<First light collector>
In the light emitting and receiving device according to the present embodiment, the first light collecting unit collects the light incident from the focal position. Here, the focal position is uniquely determined from the shape of the first light collector. When the light emitting unit is disposed at the focal point of the first light collecting unit, light emitted from the light emitting unit and reflected by the first light collecting unit is aligned in parallel with the symmetry axis direction of the first light collecting unit. As a specific shape of the first light collecting portion, it is possible to use a rotation paraboloid that can be produced when a certain parabola is rotated. The first light collector may be formed of a metal material, or may be formed by depositing or plating a metal such as aluminum on the inner surface after forming a specific shape of a material other than a metal. Good. In particular, when the light-reflecting portion is formed by vapor deposition or plating, high productivity and dimensional accuracy can be improved as compared with the case where the portion is formed of a metal material.
In the light emitting and receiving device according to the present embodiment, the first light collecting portion may have a radiation surface shape. This makes it easy to control the focal position, and can improve the accuracy of the optical path design.

<Reflection part>
In the light emitting and receiving device according to the present embodiment, the reflecting unit reflects the light collected by the first light collecting unit. The material which comprises a reflection part is not restrict | limited in particular. For example, materials such as metal, glass, ceramics, stainless steel and the like can be mentioned, but not limited thereto. From the viewpoint of improving detection sensitivity, it is preferable that the material has a small absorption coefficient of light output from the light emitting unit and a high reflectance. Specifically, a metal casing made of aluminum, an aluminum, gold, an alloy containing silver, or a resin casing coated with a laminate of these is preferable. A resin housing coated with gold or an alloy layer containing gold is preferred from the viewpoint of reliability and aging. In the case of a resin case, since it can be formed by injection molding, it may be preferable from the viewpoint of productivity.
Further, in the light emitting and receiving device according to the present embodiment, the light collected by the first light collecting portion may be reflected a plurality of times by the reflecting portion. As a result, a light emitting and receiving device with a long optical path length is realized, and the accuracy of gas concentration detection can be further improved.

<Second condenser>
In the light emitting and receiving device according to the present embodiment, the second light collecting unit condenses the light reflected by the reflecting unit at a focal position. Here, the focal position is uniquely determined from the shape of the second light collector. When the light receiving unit is disposed at the focal point of the second light collecting unit, light incident in parallel to the symmetry axis direction of the second light focusing unit is incident on the light receiving unit provided at the focal position of the second light focusing unit. As a specific shape of the second light collecting portion, a paraboloid of revolution produced when a certain parabola is rotated can be used. The second light collecting portion may be formed of a metal material, or after forming a specific shape of a material other than a metal, the inner surface thereof is a metal such as aluminum, gold or silver, or an alloy of these metals. It may be formed by vapor deposition or plating. In particular, when the light-reflecting portion is formed by vapor deposition or plating, cost reduction and improvement in dimensional accuracy can be achieved as compared with the case where the portion is formed of a metal material.
In the light emitting and receiving device according to the present embodiment, the second light collector may have a radiation surface shape. This makes it easy to control the focal position, and can improve the accuracy of the optical path design.

<Signal processing unit>
The light emitting and receiving device according to the present embodiment may further include a signal processing unit to which the output of the light receiving unit is input. The signal processing unit is not particularly limited as long as it can perform calculation in gas concentration calculation, and for example, an analog IC, a digital IC, a central processing unit (CPU), and the like are preferable. The signal processing unit may include a function for controlling the light source. Further, the signal processing unit may calculate the concentration of the gas to be detected from the output signal of the light receiving unit, and may output it as a digital or analog electric signal. Alternatively, when the gas to be detected has a predetermined concentration or more (or a predetermined concentration or less), a digital signal corresponding to the determination may be output.

<Sealing part>
The light emitting and receiving device according to the present embodiment may further include a sealing unit that integrally seals the light emitting unit, the light receiving unit, and the signal processing unit. As a material of the sealing portion, for example, a resin mold material or the like can be used. <Others>
In the light emitting and receiving device according to the present embodiment, the second light receiving unit is further formed on the substrate on which the light emitting unit is formed, and the second light emitting unit is further formed on the substrate on which the light receiving unit is formed. Is also conceivable. By alternately driving the two light emitting units, it is possible to periodically perform, for example, correction of deterioration of the light emitting units.

Further, in an application in which the deterioration of the light emitting part is not remarkable, both light sources can be alternately driven to suppress the temperature difference between the sensors on both sides. By reducing this temperature difference, one of the light receiving portions receives the light from the internal reflection of the substrate, and the other light receiving portion receives the light signal attenuated by the absorption of the gas to be detected, and divides both signals. Thus, the temperature characteristics of the light emitting / receiving unit can be offset. The reason why this temperature characteristic can be improved is because light emission and light reception are alternately performed, so it may be preferable that the shape of the optical path be symmetrical so that the optical paths in both directions become equal.
In the light emitting and receiving device according to the present embodiment, the light emitting unit is installed at the focal position of the first light collecting unit. However, as another embodiment, the light emitting unit is provided at the focus of the first light collecting unit. It is possible to think about the form which does not exist. Similarly, although the light receiving unit has been described as being installed at the focal position of the second light collecting unit, another embodiment is also conceivable in which the light receiving unit is not provided at the focus of the second light collecting unit. .

Further, in the present embodiment, the form (imaging system) in which the light emitting unit and the light receiving unit are respectively at the focal positions of the first light collecting unit and the second light collecting unit has been described. It is also conceivable that the focusing part is a normal reflecting mirror having no focus (non-imaging system). In this case, the light emitted from the light emitting unit is not condensed at a specific place, but the degree of freedom in optical path design is further enhanced, and a light emitting and receiving device with a longer optical path length can be realized.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
1 (a) to 1 (c) are block diagrams for explaining the first embodiment of the light emitting and receiving device according to the present invention, FIG. 1 (a) is a top view, and FIG. 1 (b) is FIG. FIG. 1 (c) shows a perspective view taken along the line AA 'of FIG. Reference numeral 200 denotes a mounting unit, and reference numeral 400 denotes an optical path (FIG. 7). In the drawings described below, parts having the same configuration are given the same reference numerals, and repeated descriptions thereof will be omitted.

  As shown in FIG. 1, the light emitting and receiving device 100 according to the first embodiment outputs light including a wavelength absorbed by the gas to be detected, and the light emitting unit 1 installed at the focal position of the first light collecting unit 3. A first light collecting unit 3 for collecting light incident from the light emitting unit 1, a reflecting unit 4 for reflecting the light collected by the first light collecting unit 3, and a focal position for the light reflected by the reflecting unit 4 And a light receiving unit 2 disposed at a focal position of the second light collecting unit 5.

  According to the light emitting and receiving device 100 according to the first embodiment, a part of the light emitted from the light emitting unit 1 is collected by the first light collecting unit 3 in a specific direction. The collected light is reflected by the reflecting portion 4 and is incident on the second light collecting portion 5 from a specific direction. The second condensing unit 5 condenses the light incident from the specific direction to the position of the light receiving unit 2 which is the focal position. As a result, most of the light emitted from the light emitting unit 1 is incident on the light receiving unit while earning the number of reflections, so that a signal with a high S / N ratio can be obtained. The light emitting device 100 can be realized.

FIG. 7 is a view showing a mounting state of the light emitting and receiving device of the embodiment 1 shown in FIGS. 1 (a) to 1 (c). In addition, the code | symbol 300 has shown the printed circuit board. That is, as shown in FIG. 7, the light emitting and receiving device 100 can be easily mounted on a mounting substrate such as the printed substrate 300 using the adhesive 102 and the solder 101.
As the mounting method, there are the following two methods.
(1) First, the mounting portion 200 is fixed on the printed circuit board 300 by solder, and finally, the optical path portion 400 is fixed by the adhesive 102.

(2) The integrated mounting portion 200 and the optical path portion 400 are mounted on a printed circuit board by solder and an adhesive.
Electrical connection between the mounting portion and the printed circuit board 300 is made by the exposed part of the lead frame 11 and the solder 102. In the method (i), when the optical path portion 400 is made of resin, there is a possibility that sufficient heat resistance may not be obtained at the time of solder reflow of the mounting portion 200, which may be preferable. In the method (ii), the light path 400 needs to be a heat-resistant material. Specific materials include ceramic and polyphenylene sulfide (PPS) resin.

Second Embodiment
FIG. 2 is a configuration diagram for explaining a second embodiment of the light emitting and receiving device according to the present invention. As shown in FIG. 2, the light emitting and receiving device 100 according to the second embodiment includes reflecting portions 4 a and 4 b that reflect light collected by the first light collecting portion 3 a plurality of times.
According to the light emitting and receiving device 100 according to the second embodiment, a part of the light emitted from the light emitting unit 1 is collected by the first light collecting unit 3 in a specific direction. The collected light is reflected a plurality of times by the reflecting portions 4a and 4b, and then enters the second light collecting portion 5 from a specific direction. The second light collector 5 condenses the light incident from the specific direction to the position of the light receiver 2 which is the focal position. As a result, most of the light emitted from the light emitting unit 1 is incident on the light receiving unit 2 while earning the number of reflections, so that a signal with a high S / N ratio can be obtained, thereby making it compact and highly accurate. A light emitting and receiving device can be realized.
Third Embodiment
FIG. 3 is a configuration diagram for explaining a third embodiment of the light emitting and receiving device according to the present invention. As shown in FIG. 3, the light emitting / receiving device 100 of Embodiment 3 integrally seals the signal processing unit 6 to which the output of the light receiving unit 2 is input, the light emitting unit 1, the light receiving unit 2, and the signal processing unit 6. The sealing portion 7 is further provided. Further, FIG. 6 described later shows the light emitting unit 1, the light receiving unit 2, the signal processing unit 6, and the sealing unit 7 at this time.

In the first and second embodiments described above, the reflective portion 4 is disposed only on the opposite side of the light emitting portion 1 and the light receiving portion 2, while the reflective portion in the light emitting and receiving device 100 of the third exemplary embodiment 41 is arranged at four corners in the light emitting and receiving device 100 to perform multiple reflections.
According to the light emitting and receiving device 100 according to the third embodiment, the light emitting unit 1, the light receiving unit 2 and the signal processing unit 6 are integrally sealed, so that the device can be further miniaturized even in the case of the same optical path length. It becomes possible. Here, since the light emitting unit 1, the light receiving unit 2 and the signal processing unit 6 can be realized by a small sealing unit, there are cases where it is preferable from the viewpoint of productivity. In addition, by being integrally sealed, it is possible to freely use other spaces for the design of the optical path, and the degree of freedom of the optical path design is increased.

FIG. 5 is a perspective view of the light emitting and receiving device according to the third embodiment shown in FIG. Here, the optical filters 8 a and 8 b having wavelength selectivity are mounted on the light emitting surface side of the light emitting unit 1 and the light receiving surface side of the light receiving unit 2. Moreover, the filter holding part 9 which hold | maintains optical filter 8a, 8b is provided.
FIG. 6 is a cross-sectional view taken along the line BB 'of FIG. Reference numeral 11 denotes a lead frame, and 12 denotes a wire connecting the signal processing unit 6 and the lead frame 11.

Fourth Embodiment
FIG. 4 is a configuration diagram for explaining a fourth embodiment of the light emitting and receiving device according to the present invention. As shown in FIG. 4, in the light emitting and receiving device 100 of the fourth embodiment, the light emitting unit 1 and the light receiving unit 2 are more closely sealed in the light emitting and receiving device shown in FIG. 3.
According to the light emitting and receiving device 100 according to the fourth embodiment, it is possible to reduce the temperature difference between the light emitting unit 1 and the light receiving unit 2 while further lengthening the optical path length, and easily perform signal processing such as temperature correction. It becomes possible. In addition, since the first light collecting part and the second light collecting part can be designed to have a width enough to accommodate the light emitting part 1 and the light receiving part 2 and the focal distance can be as close to the origin as possible, .
Similar to the reflection unit 41 in FIG. 3 described above, the reflection unit 41 of the light emission and reception device 100 of the fourth embodiment is disposed at four corners in the light emission and reception device 100 to perform reflection a plurality of times. .

Other Embodiments
8 (a) and 8 (b) are configuration diagrams for describing another embodiment of the light emitting and receiving device according to the present invention, FIG. 8 (a) is a top view, and FIG. It is a CC 'line sectional view of a).
As another embodiment, the light emitting and receiving device shown in FIGS. 8A and 8B can be considered. The light emitting and receiving device 100 has an optical design of a non-imaging system, and the light emitted from the light emitting unit 1 is collected at a specific place although it is reflected via the reflecting unit 42 that reflects the light multiple times. Since the degree of freedom in designing an optical path is further increased, it is possible to realize a light emitting and receiving device having a longer optical path length.
Although the description so far does not show the openings for introducing and extracting the detected gas, there is no limitation unless it is a place where the efficiency of light emission and light reception is reduced. In addition, in order to prevent the introduction of dust and the like with the gas to be detected, a filter or the like may be provided at the opening.

Although not shown, as another embodiment of the light emitting and receiving device according to the present invention, lids may be provided on the upper and lower portions of the light emitting and receiving device 100. The material of the lid is not particularly limited. By providing the lid, dust can be prevented from entering the light path of the light emitting and receiving device 100, and the light collection ratio can be increased, which may be preferable in some cases. These lids may be formed integrally with the light emitting and receiving device 100 at the time of manufacture. In this case, it may be preferable from the viewpoint of productivity.
The present invention is not limited to the embodiments described above. Modifications of the design may be added to the embodiment based on the knowledge of those skilled in the art, and the first to fourth embodiments and other embodiments may be arbitrarily combined, and such modifications are added. Embodiments are also included within the scope of the present invention.

Reference Signs List 1 light emitting unit 2 light receiving unit 3 first light collecting unit 4, 4a, 4b, 41, 42 reflecting unit 5 second light collecting unit 6 signal processing unit 7 sealing unit 8a, 8b optical filter 9 filter holding unit 11 lead frame 12 Wire 100 Light emitting and receiving device 101 Solder 102 Adhesive 200 Mounting portion 300 Printed circuit board 400 Optical path portion

Claims (4)

A light emitting unit that outputs light absorbed by the gas to be detected ;
A light receiving unit,
A first condensing unit that condenses light incident from a focal position;
A first reflecting portion that reflects the light collected by the first light collecting portion;
A second reflecting portion that reflects the light reflected by the first reflecting portion;
A third reflecting portion that reflects the light reflected by the second reflecting portion;
A second light collecting portion for collecting the light reflected by the third reflecting portion at a focal position;
A signal processing unit to which the output of the light receiving unit is input;
A sealing portion provided in a space into which the gas to be detected is introduced and integrally sealing the light emitting portion, the light receiving portion, and the signal processing portion;
A light emitting and receiving device comprising
The light emitting unit, the light receiving unit, the first light collecting unit, the second light collecting unit, and the second reflecting unit are disposed on one side of the light emitting and receiving device in plan view.
The first reflecting portion and the third reflecting portion are disposed on the other side of the light emitting and receiving device across the space in plan view,
The light emitting unit is disposed at a focal position of the first light collecting unit, and the light receiving unit is disposed at a focal position of the second light collecting unit.
The second reflection part is disposed on the other side of the light emitting and receiving device with the reflection surface of the second reflection part facing the other side.
The first reflection portion and the third reflection portion are disposed on one side of the light emitting and receiving device with the reflection surface of the first reflection portion and the reflection surface of the third reflection portion facing each other,
The light collected by the first light collector is a plurality of times between the one side and the other side of the light emitting and receiving device by the first reflector, the second reflector, and the third reflector. is reflected, the in the space attenuated is absorbed by the detected gas, the light receiving unit that is used in the concentration measurement of the detected gas based on the optical signal after attenuation of light received the light receiving and emitting device. The second reflecting portion is disposed between the light emitting portion and the light receiving portion, and the reflecting surface of the second reflecting portion is disposed parallel to a direction in which the light emitting portion and the light receiving portion are arranged. Yes,
The first reflecting portion is disposed at a position separated from the light emitting portion in a direction perpendicular to the direction in which the light emitting portion and the light receiving portion are arranged, and the reflecting surface of the first reflecting portion is the second reflecting portion. Are placed towards
The third reflecting portion is disposed at a position separated from the light receiving portion in a direction perpendicular to the direction in which the light emitting portion and the light receiving portion are arranged, and the reflecting surface of the third reflecting portion is the second reflecting portion The light emitting and receiving device according to claim 1, wherein   The light emitting and receiving device according to claim 1, wherein the first light collecting unit and the second light collecting unit have a radiation surface shape. The first light collecting portion, the second reflecting portion, and the second light collecting portion are integrally formed of the same material,
The light emitting and receiving device according to any one of claims 1 to 3 , wherein the first reflecting portion and the third reflecting portion are integrally formed of the same material.

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