JP2017161404A - Optical component sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical component sensor capable of highly accurately detecting a component.SOLUTION: An optical component sensor 1 comprises: a detection light source 21 which emits detection light LD1; a reference light source 22 which emits reference light LR1; a light projecting unit 40 which emits emission detection light LD2 which is reflected light by a concave reflection mirror 41, and emission reference light LR2 toward an object 2; a detection light-receiving element 31 which receives reflection detection light LD3 which is reflected light by the object 2; a reference light-receiving element 32 which receives reflection reference light LR3 which is reflected light by the object 2; and a signal processing circuit 80 which detects a component contained in the object 2 on the basis of a detection signal corresponding to the reflection detection light LD3 and a reference signal corresponding to the reflection reference light LR3. The detection light source 21 is arranged at a position different from a position on an optical path of the emission reference light LR2. The reference light source 22 is arranged at a position different from a position on an optical path of the emission detection light LD2. Optical axes of the emission detection light LD2 and the emission reference light LR2 are parallel each other, and intensity distributions of these lights in a cross section orthogonal to the optical axes substantially match each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical component sensor that detects a predetermined component using detection light and reference light.

  Conventionally, a photoelectric sensor capable of discriminating a detection object at a long distance is known (see, for example, Patent Document 1). The reflective photoelectric sensor described in Patent Document 1 includes a light projecting unit that irradiates a detection object with two lights having different wavelengths, a reflection plate that reflects one of the two lights, and a detection object or reflection. And a light receiving unit that receives light reflected by the plate. According to the reflective photoelectric sensor, it is possible to know the presence / absence of a detection object by processing the light reception signal output from the light receiving unit.

JP-A-8-255533

  In the reflective photoelectric sensor described in Patent Document 1, the light projecting unit includes two light emitting elements whose optical axes coincide with each other, and the two light emitting elements are arranged so that their emission surfaces are in opposite directions. Yes. The light emitted from one of the two light emitting elements is reflected by the reflecting plate and emitted to the outside through the light projecting lens. That is, since the light emitting element is arranged in the reflection direction of the reflecting plate, the light reflected by the reflecting plate is blocked by the light emitting element, and the light energy emitted to the outside is reduced. Thereby, the detection accuracy of a component falls.

  Accordingly, an object of the present invention is to provide an optical component sensor that can accurately detect a component.

  To achieve the above object, an optical component sensor according to an aspect of the present invention includes a first light source that emits detection light that includes an absorption wavelength due to a predetermined component, and a reference light that does not include the absorption wavelength due to the component. Two light sources, a housing that houses the first light source and the second light source, a concave reflecting mirror that is housed in the housing and reflects the detection light and the reference light, and is reflected by the concave reflecting mirror The outgoing detection light that is at least a part of the detected light and the outgoing reference light that is at least a part of the reference light reflected by the concave reflecting mirror are applied to an object located outside the casing. A light projecting unit that emits light toward the light source, a first light receiving element housed in the housing that receives reflected detection light that is at least part of the emission detection light reflected by the object, and the object. Reflection A second light receiving element housed in the housing for receiving reflected reference light that is at least part of the emitted reference light, and a detection signal corresponding to the reflected detection light output from the first light receiving element And a signal processing circuit that detects the component included in the object based on a reference signal corresponding to the reflected reference light output from the second light receiving element, and the first light source includes the concave surface The second light source is disposed at a position different from the optical path of the detection light reflected by the concave reflection mirror, and is disposed at a position different from the optical path of the reference light reflected by the reflection mirror. In addition, in the emission reference light, the respective optical axes are parallel to each other, and the intensity distributions in the cross section perpendicular to the optical axis substantially coincide with each other.

  With the optical component sensor according to the present invention, components can be detected with high accuracy.

It is a schematic diagram which shows the structure of the optical component sensor which concerns on embodiment. It is a block diagram which shows the function structure of the optical component sensor which concerns on embodiment. It is a figure which shows an example of the optical path of the detection light of the optical component sensor which concerns on embodiment. It is a figure which shows an example of the optical path of the reference light of the optical component sensor which concerns on embodiment. It is a figure which shows the absorption spectrum of a water | moisture content. It is a figure which shows the spectrum of the detection light of the optical component sensor which concerns on embodiment, and reference light. It is a figure which shows the sensitivity characteristic of the light receiving element of the optical component sensor which concerns on embodiment. It is a figure which shows the structure of the light projection part of the optical component sensor which concerns on embodiment. It is a figure which shows intensity distribution of the emitted detection light which concerns on embodiment, and the emitted reference light. It is a figure which shows the transmission spectrum of the optical filter of the optical component sensor which concerns on embodiment. It is a figure which shows the structure of the light projection part which concerns on the modification 1. FIG. It is a figure which shows the structure of the light projection part which concerns on the modification 2. FIG. It is a figure which shows the structure of the light projection part which concerns on the modification 3. FIG.

  Below, the optical component sensor which concerns on embodiment of this invention is demonstrated in detail using drawing. Note that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangement and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a mimetic diagram and is not necessarily illustrated strictly. Therefore, for example, the scales and the like do not necessarily match in each drawing. Moreover, in each figure, the same code | symbol is attached | subjected about the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment)
[Overview]
First, an outline of the optical component sensor according to the embodiment will be described.

  FIG. 1 is a diagram showing a configuration of an optical component sensor 1 according to the present embodiment. FIG. 2 is a block diagram showing a functional configuration of the optical component sensor 1 according to the present embodiment. 3A and 3B are diagrams showing examples of optical paths of detection light and reference light of the optical component sensor 1 according to the present embodiment, respectively. 3A and 3B show only typical optical paths of the detection light and the reference light, respectively.

  The optical component sensor 1 irradiates the object 2 with two lights having different wavelengths (the emission detection light LD2 and the emission reference light LR2), and the light reflected by the object 2 (the reflection detection light LD3 and the reflection reference light LR3). Is a non-contact optical component sensor that detects a component contained in the object 2 by receiving light. In the present embodiment, as shown in FIGS. 3A and 3B, the optical component sensor 1 detects moisture contained in the object 2 located at a position separated from the space 3.

  The object 2 is, for example, clothing or the like when not particularly limited. For example, by attaching the optical component sensor 1 to a clothes dryer or the like, it is possible to check the drying condition of the clothes. Thereby, generation | occurrence | production of the pain of the clothing by drying too much can be suppressed.

  The space 3 is a space (free space) between the optical component sensor 1 and the object 2. The space 3 is an external space of the housing 10 of the optical component sensor 1.

  As shown in FIG. 1, the optical component sensor 1 includes a housing 10, a detection light source 21, a reference light source 22, a detection light receiving element 31, a reference light receiving element 32, and a concave reflecting mirror 41. The light projecting unit 40 includes a detection lens 51, a reference lens 52, a detection filter 61, and a reference filter 62. As shown in FIG. 2, the optical component sensor 1 includes a control circuit 70 and a signal processing circuit 80.

  Below, each component of the optical component sensor 1 is demonstrated in detail.

[Case]
The housing 10 is a housing that houses the detection light source 21 and the reference light source 22. As shown in FIG. 1, the housing 10 further includes a detection light receiving element 31, a reference light receiving element 32, a concave reflecting mirror 41, a detection lens 51, a reference lens 52, a detection filter 61, and a reference. A filter 62 is accommodated.

  The housing 10 is made of a light shielding material. Thereby, it can suppress that external light injects into the housing | casing 10. FIG. Specifically, the housing 10 has a light shielding property against light received by the detection light receiving element 31 and the reference light receiving element 32. More specifically, the housing 10 has a light blocking property with respect to the reflected detection light LD3 (detection light LD1) and the reflected reference light LR3 (reference light LR1), and is formed of, for example, a resin material or a metal material. .

  An opening is provided in the outer wall of the housing 10, and a detection lens 51 and a reference lens 52 are attached to the opening. Although not shown, the detection light source 21 and the reference light source 22 emit on the outer wall of the housing 10 and the light reflected by the concave reflection mirror 41 (the emission detection light LD2 and the emission reference light LR2) is emitted to the outside. An opening is provided for this purpose.

[Light source for detection]
The detection light source 21 is an example of a first light source that emits detection light LD1 including an absorption wavelength of a predetermined component. Specifically, the detection light source 21 is a dispersed light source that emits detection light LD1 including an absorption wavelength due to moisture as a peak wavelength. As shown in FIG. 3A, the detection light LD1 emitted from the detection light source 21 is reflected by the concave reflecting mirror 41 and emitted to the outside of the housing 10 as emission detection light LD2.

  FIG. 4 is a diagram showing an absorption spectrum of moisture. As shown in FIG. 4, moisture has absorption peaks at wavelengths of about 1450 nm and about 1900 nm. In the present embodiment, as shown in FIG. 5, the detection light LD1 is infrared light including 1450 nm, which is an absorption wavelength due to moisture, as a peak wavelength. Here, FIG. 5 is a diagram illustrating the spectra of the detection light and the reference light of the optical component sensor 1 according to the present embodiment.

  The detection light source 21 is, for example, a light emitting element that emits infrared light having a spectrum indicated by a solid line in FIG. The light emitting element is, for example, an LED (Light Emitting Diode) element, but is not limited thereto. As the light emitting element, a semiconductor laser element or an organic EL (Electro Luminescence) element may be used.

  The light source for detection 21 is arranged at a position different from the optical path of the reference light reflected by the concave reflecting mirror 41 (in this embodiment, the outgoing reference light LR2). Specifically, the detection light source 21 is arranged at a position where it does not interfere with the reference light emitted from the reference light source 22. As shown in FIG. 3B, for example, the detection light source 21 is arranged at a position different from the optical path of the reference light LR1 emitted from the reference light source 22, and is interposed between the reference light source 22 and the concave reflecting mirror 41. Not placed. Further, for example, the detection light source 21 is disposed at a position different from the optical path of the reflected reference light LR3, and is not disposed between the reference lens 52 and the reference light receiving element 32. In the present embodiment, the detection light source 21 is disposed so as to face the reference light receiving element 32 with the concave reflection mirror 41 interposed therebetween.

[Reference light source]
The reference light source 22 is an example (dispersed light source) of a second light source that emits reference light LR1 that does not include an absorption wavelength due to a predetermined component. As shown in FIG. 5, the reference light LR1 does not include a wavelength of about 1450 nm that is an absorption wavelength due to moisture, but includes, for example, a wavelength of about 1300 nm different from the absorption wavelength as a peak wavelength. As shown in FIG. 3B, the reference light LR1 emitted from the reference light source 22 is reflected by the concave reflecting mirror 41 and emitted to the outside of the housing 10 as outgoing reference light LR2.

  Note that not including the absorption wavelength does not mean only not including the absorption wavelength at all. The reference light LR1 may include an absorption wavelength whose intensity is sufficiently smaller than the peak wavelength. For example, the reference light LR1 may include an absorption wavelength with an intensity smaller than the detection resolution.

  The reference light source 22 is, for example, a light emitting element that emits infrared light having a spectrum indicated by a broken line in FIG. That is, the reference light source 22 emits infrared light including a peak wavelength that is different from the peak wavelength of the infrared light emitted from the detection light source 21. The light emitting element is, for example, an LED element, but may be a semiconductor laser element or an organic EL element.

  The reference light source 22 is disposed at a position different from the optical path of the detection light (in this embodiment, the emission detection light LD2) reflected by the concave reflecting mirror 41. Specifically, the reference light source 22 is disposed at a position where it does not interfere with the detection light emitted from the detection light source 21. As shown in FIG. 3A, for example, the reference light source 22 is disposed at a position different from the optical path of the detection light LD1 emitted by the detection light source 21, and is interposed between the detection light source 21 and the concave reflecting mirror 41. Not placed. Further, for example, the reference light source 22 is disposed at a position different from the optical path of the reflected detection light LD3, and is not disposed between the detection lens 51 and the detection light receiving element 31. In the present embodiment, the reference light source 22 is disposed so as to face the detection light receiving element 31 with the concave reflection mirror 41 interposed therebetween.

[Light-receiving element for detection]
The light receiving element 31 for detection is an example of a first light receiving element that receives the reflected detection light LD3 that is at least a part of the outgoing detection light LD2 reflected by the object 2. The detection light receiving element 31 photoelectrically converts the received reflected detection light LD3 to generate a detection signal that is an electrical signal corresponding to the amount of received light (that is, intensity) of the reflected detection light LD3. The generated detection signal is output to the signal processing circuit 80.

  The reflection detection light LD3 is light obtained by reflecting the emission detection light LD2 by the object 2. The peak wavelength of the reflected detection light LD3 is the same as the peak wavelength of the outgoing detection light LD2, that is, the peak wavelength (about 1450 nm) of the detection light LD1.

  FIG. 6 is a diagram showing sensitivity characteristics of the light receiving element of the optical component sensor 1 according to the present embodiment. In the present embodiment, a light receiving element having the characteristics shown in FIG. 6 is used for each of the detection light receiving element 31 and the reference light receiving element 32.

  Specifically, as shown in FIG. 6, the light receiving sensitivity of the detection light receiving element 31 has a positive correlation with a wavelength in the range of 1000 nm to 1600 nm. The light receiving sensitivity of the detection light receiving element 31 is not limited to this, and may be, for example, a substantially constant sensitivity with respect to each wavelength.

  As described above, the detection light receiving element 31 has sufficiently high light reception sensitivity with respect to the peak wavelength of the reflected detection light LD3 (detection light LD1). Therefore, the detection light receiving element 31 can receive the reflection detection light LD3 and generate an electrical signal (detection signal) corresponding to the amount of received light.

  The detection light receiving element 31 is accommodated in the housing 10. For example, the detection light receiving element 31 is fixed in the housing 10 so that the light receiving surface is positioned at the focal point of the detection lens 51.

  The detection light receiving element 31 is, for example, a photodiode, but is not limited thereto. For example, the detection light receiving element 31 may be a phototransistor or an image sensor. The detection light receiving element 31 and the reference light receiving element 32 may use different regions of one image sensor.

[Reference light receiving element]
The reference light receiving element 32 is an example of a second light receiving element that receives the reflected reference light LR3 that is at least a part of the outgoing reference light LR2 reflected by the object 2. The reference light receiving element 32 photoelectrically converts the received reflected reference light LR3 to generate a reference signal that is an electrical signal corresponding to the amount of light received by the reflected reference light LR3. The generated reference signal is output to the signal processing circuit 80.

  The reflected reference light LR3 is light obtained by reflecting the outgoing reference light LR2 by the object 2. The peak wavelength of the reflected reference light LR3 is the same as the peak wavelength of the outgoing reference light LR2, that is, the peak wavelength (about 1300 nm) of the reference light LR1.

  The light receiving sensitivity of the reference light receiving element 32 has the characteristics shown in FIG. That is, the reference light receiving element 32 has sufficiently high light receiving sensitivity with respect to the peak wavelength of the reflected reference light LR3 (reference light LR1). Therefore, the reference light receiving element 32 can receive the reflected reference light LR3 and generate an electrical signal (reference signal) corresponding to each received light amount.

  The reference light receiving element 32 is accommodated in the housing 10. For example, the reference light receiving element 32 is fixed in the housing 10 so that the light receiving surface is located at the focal point of the reference lens 52.

  The reference light receiving element 32 is, for example, a photodiode, but is not limited thereto. For example, the reference light receiving element 32 may be a phototransistor or an image sensor.

[Concave reflection mirror (projecting part)]
The light projecting unit 40 emits the emission detection light LD2 and the emission reference light LR2 toward the object 2. The emission detection light LD2 and the emission reference light LR2 have substantially the same intensity distribution in a cross section in which each optical axis is parallel and orthogonal to the optical axis. The light projecting unit 40 emits the emission detection light LD2 and the emission reference light LR2 from the housing 10 toward the object 2 with the same spot size.

  FIG. 7 is a diagram illustrating a configuration of the light projecting unit 40 in the optical component sensor 1 according to the present embodiment. As shown in FIGS. 7 and 2, the light projecting unit 40 includes a concave reflecting mirror 41 that reflects the detection light LD1 and the reference light LR1.

  As shown in FIG. 7, the concave reflecting mirror 41 has, for example, one concave reflecting surface 42, and the detection light LD 1 and the reference light LR 1 are reflected by the reflecting surface 42. At least a part of the detection light LD1 reflected by the concave reflecting mirror 41 is the emission detection light LD2. At least a part of the reference light LR1 reflected by the concave reflecting mirror 41 is the outgoing reference light LR2. In the present embodiment, the detection light LD1 and the reference light LR1 are reflected by the reflection surface 42 of the concave reflecting mirror 41, for example, at the same light distribution angle in the same direction, and are used as the emission detection light LD1 and the emission reference light LR2. proceed.

  The reflection surface 42 is, for example, a part of a paraboloid of revolution or a spheroid. In the present embodiment, it has a shape in which two rotating parabolas with parallel axes and different focal points are combined. The two paraboloids form one smooth concave surface. That is, the two paraboloids have a smooth and continuous slope.

  One of the two paraboloids mainly reflects the detection light LD1 as the emission detection light LD2. Specifically, the detection light source 21 is disposed at the focal point of the one paraboloid. Accordingly, the one paraboloid of revolution can reflect the detection light LD1 as the emission detection light LD2 in a direction parallel to the axis.

  The other paraboloid mainly reflects the reference light LR2 as the outgoing reference light LR2. Specifically, the reference light source 22 is disposed at the focal point of the other paraboloid. As a result, the other paraboloid of revolution can reflect the reference light LR2 as the outgoing reference light LR2 in a direction parallel to the axis.

  Since the axes of the two paraboloids are parallel, the optical axes of the outgoing detection light LD2 and the outgoing reference light LR2 can be made parallel. The optical axis corresponds to the optical path of light having the maximum energy intensity.

  The one rotation paraboloid is a part of the reflection surface 42 on the reference light source 22 side, and the other rotation paraboloid is a part of the reflection surface 42 on the detection light source 21 side. That is, in the present embodiment, as shown in FIG. 7, the reflection surface 42 is irradiated so that the detection light LD1 and the reference light LR1 intersect. For this reason, the optical axis of the outgoing detection light LD2 is located on the reference light source 22 side, and the optical axis of the outgoing reference light LR2 is located on the detection light source 21 side.

  The concave reflecting mirror 41 is formed, for example, by depositing a metal thin film on a resin molded body having a concave surface having the same shape as the reflecting surface 42 by a vapor deposition method or the like. The metal thin film may be formed only on the concave surface or may be formed on the entire surface of the resin molded body. The reflection surface 42 may be mirror-finished.

  FIG. 8 is a diagram showing intensity distributions of the emission detection light LD2 and the emission reference light LR2 according to the present embodiment. Specifically, FIG. 8 shows intensity distributions in cross sections orthogonal to the optical axes of the outgoing detection light LD2 and the outgoing reference light LR2. In FIG. 8, the horizontal axis represents a position in a cross section perpendicular to each optical axis, and the vertical axis represents the energy intensity of each light.

  As shown in FIG. 8, the intensity distributions of the emission detection light LD2 and the emission reference light LR2 are substantially the same. Specifically, the position where the energy intensity is maximum is slightly shifted. This is because the positions of the optical axes of the emission detection light LD2 and the emission reference light LR2 are slightly shifted as shown in FIG. The distance between each optical axis is designed to an appropriate value according to the use and specifications of the optical component sensor 1 (irradiation area, distance to the object 2) and the like. For example, when a region with a diameter of 30 cm is irradiated with the emission detection light LD2 and the emission reference light LR2 to detect a change rate of a 5% moisture content, the optical axis deviation is designed to be 1 cm or less.

[Detection lens]
The detection lens 51 is a condensing lens for condensing the reflected detection light LD3 reflected by the object 2 onto the detection light receiving element 31. For example, the detection lens 51 is fixed to the housing 10 so that the focal point is located on the light receiving surface of the detection light receiving element 31. The detection lens 51 is, for example, a resin convex lens, but is not limited thereto.

[Reference lens]
The reference lens 52 is a condensing lens for condensing the reflected reference light LR <b> 3 reflected by the object 2 on the reference light receiving element 32. For example, the reference lens 52 is fixed to the housing 10 so that the focal point is located on the light receiving surface of the reference light receiving element 32. The reference lens 52 is, for example, a resin convex lens, but is not limited thereto.

[Detection filter]
The detection filter 61 is an example of a first filter provided on the optical path of the reflected detection light LD3 incident on the detection light receiving element 31. In the present embodiment, as shown in FIG. 1, the detection filter 61 is disposed between the detection lens 51 and the detection light receiving element 31. The detection filter 61 transmits the reflected detection light LD3 and absorbs the reflected reference light LR4. For this reason, as shown in FIG. 3B, the reflected reference light LR4 is absorbed by the detection filter 61 and hardly reaches the detection light receiving element 31.

  FIG. 9 is a diagram showing a transmission spectrum of the optical filter according to the present embodiment. As shown in FIG. 9, the detection filter 61 transmits 1450 nm light, which is the peak wavelength of the reflected detection light LD3, and absorbs 1300 nm light, which is the peak wavelength of the reflected reference light LR4. The detection filter 61 may transmit a part of 1300 nm light. That is, the detection filter 61 may transmit the reflected reference light LR4 with a transmission amount smaller than the transmission amount of the reflected detection light LD3.

[Filter for reference]
The reference filter 62 is an example of a second filter provided on the optical path of the reflected reference light LR3 incident on the reference light receiving element 32. In the present embodiment, as shown in FIG. 1, the reference filter 62 is disposed between the reference lens 52 and the reference light receiving element 32. The reference filter 62 transmits the reflected reference light LR3 and absorbs the reflected detection light LD4. For this reason, as shown in FIG. 3A, the reflection detection light LD4 is absorbed by the reference filter 62 and hardly reaches the reference light receiving element 32.

  As shown in FIG. 9, the reference filter 62 transmits 1300 nm light, which is the peak wavelength of the reflected reference light LR3, and absorbs light of 1450 nm, which is the peak wavelength of the reflected detection light LD4. Note that the reference filter 62 may transmit a part of light of 1450 nm. That is, the reference filter 62 may transmit the reflected detection light LD4 with a transmission amount smaller than the transmission amount of the reflected reference light LR3.

[Control circuit]
The control circuit 70 individually controls the light emission of the detection light source 21 and the light emission of the reference light source 22. Specifically, the control circuit 70 can independently control the light emission and extinction of the detection light source 21 and the light emission and extinction of the reference light source 22.

  For example, the control circuit 70 causes the detection light source 21 and the reference light source 22 to emit light exclusively in time. That is, the light emission period of the detection light source 21 and the light emission period of the reference light source 22 do not overlap. Specifically, the control circuit 70 causes the detection light source 21 and the reference light source 22 to repeatedly emit light alternately and exclusively in time. For example, the control circuit 70 outputs a pulse signal having a predetermined frequency (for example, 1 kHz) to the detection light source 21 and the reference light source 22. The pulse signal output to the detection light source 21 and the pulse signal output to the reference light source 22 are synchronized so that the respective pulses do not overlap.

  For example, the pulse signal of the detection light source 21 is a pulse signal having an on-duty ratio of 50% or less. The pulse signal of the reference light source 22 is a pulse signal obtained by shifting the phase of the pulse signal of the detection light source 21 by 180 degrees. Thereby, the light emission period of the detection light source 21 and the light emission period of the reference light source 22 can be made to have the same length and not overlap each other.

  Although not shown in FIG. 1, the control circuit 70 may be housed in the housing 10 or attached to the outer surface of the housing 10. Alternatively, the control circuit 70 may have a communication function such as wireless communication, and may transmit a control pulse signal to the detection light source 21 and the reference light source 22.

  The control circuit 70 is composed of, for example, a drive circuit and a microcontroller. The control circuit 70 includes a nonvolatile memory in which a light source control program is stored, a volatile memory that is a temporary storage area for executing the program, an input / output port, and a processor that executes the program.

[Signal processing circuit]
Based on the detection signal corresponding to the reflected detection light LD3 output from the detection light receiving element 31 and the reference signal corresponding to the reflected reference light LR3 output from the reference light receiving element 32, the signal processing circuit 80 A component contained in the object 2 is detected. Specifically, the signal processing circuit 80 detects the amount of water contained in the object 2 based on the ratio (energy ratio) between the voltage level of the detection signal and the voltage level of the reference signal. A specific moisture amount detection (calculation) method will be described later.

  The signal processing circuit 80 may be accommodated in the housing 10 or attached to the outer surface of the housing 10. Alternatively, the signal processing circuit 80 may have a communication function such as wireless communication, and may receive output signals from the detection light receiving element 31 and the reference light receiving element 32.

  The signal processing circuit 80 is, for example, a microcontroller. The signal processing circuit 80 includes a nonvolatile memory in which a signal processing program is stored, a volatile memory that is a temporary storage area for executing the program, an input / output port, a processor that executes the program, and the like.

[Signal processing (detection processing)]
Next, signal processing (component detection processing) by the signal processing circuit 80 will be described.

  In the present embodiment, the signal processing circuit 80 detects the amount of component contained in the object 2 by comparing the light energy Pd of the reflected detection light LD3 and the light energy Pr of the reflected reference light LR3. The light energy Pd corresponds to the intensity of the detection signal output from the detection light receiving element 31, and the light energy Pr corresponds to the intensity of the reference signal output from the reference light receiving element 32.

  The light energy Pd of the reflected detection light LD3 incident on the detection light receiving element 31 is expressed by the following (Equation 1).

  (Formula 1) Pd = Pd0 × Gd × Rd × Td × Aa × Ivd

  Here, Pd0 is the light energy of the detection light LD1 emitted by the detection light source 21. Gd is the coupling efficiency (condensing rate) of the detection light LD1 emitted from the detection light source 21 to the detection light receiving element 31. Specifically, Gd corresponds to a ratio of a part of the detection light LD1 that becomes a part of the component diffusely reflected by the object 2 (that is, the reflection detection light LD3).

  Rd is the reflectance of the outgoing detection light LD2 by the object 2. Td is the transmittance of the reflected detection light LD3 by the detection filter 61. Ivd is the light receiving sensitivity of the detection light receiving element 31 with respect to the reflected detection light LD3.

  Aa is the absorptance of the emission detection light LD2 and the reflection detection light LD3 due to the component (moisture) contained in the object 2, and is expressed by the following (Expression 2).

(Formula 2) Aad = 10 ^{−α × C × D}

  Here, α is a predetermined extinction coefficient, specifically, the extinction coefficient of the emission detection light LD2 and the reflection detection light LD3 due to the component (water). C is the volume concentration of the component (moisture) contained in the object 2. D is a contribution thickness that is twice the thickness of the component that contributes to the absorption of the emission detection light LD2 and the reflection detection light LD3.

  More specifically, in the target object 2 in which moisture is uniformly dispersed, C is included in the component of the target object 2 when light is incident on the target object 2, reflected inside and emitted from the target object 2. This corresponds to the volume concentration. Further, D corresponds to the optical path length from the reflection inside to the emission from the object 2. For example, when the object 2 is a mesh-like solid such as a fiber or a porous solid such as a sponge, it is assumed that light is reflected on the surface of the solid. In this case, for example, C is the concentration of moisture contained in the liquid phase covering the solid matter. Moreover, D is the contribution thickness converted as an average thickness of the liquid phase which covers the solid substance.

  Therefore, α × C × D corresponds to the amount of component (water content) contained in the object 2.

  Similarly, the optical energy Pr of the reflected reference light LR3 incident on the reference light receiving element 32 is expressed by the following (Equation 3).

  (Formula 3) Pr = Pr0 * Gr * Rr * Tr * Ivr

  In the present embodiment, it can be considered that the outgoing reference light LR2 and the reflected reference light LR3 are not substantially absorbed by the components included in the object 2, so that it can be seen in comparison with (Equation 1), Light corresponding to the moisture absorption rate Aa is not included in (Equation 3).

  In (Expression 3), Pr0 is the light energy of the reference light LR1 emitted from the reference light source 22. Gr is the coupling efficiency (condensing rate) of the reference light LR1 emitted from the reference light source 22 to the reference light receiving element 32. Specifically, Gr corresponds to the ratio of a part of the reference light LR1 that becomes a part of the component diffusely reflected by the object 2 (that is, the reflected reference light LR3).

  Rr is the reflectance of the outgoing reference light LR2 by the object 2. Tr is the transmittance of the reflected reference light LR3 by the reference filter 62. Ivr is the light receiving sensitivity of the reference light receiving element 32 with respect to the reflected reference light LR3.

  In the present embodiment, since the emission detection light LD2 and the emission reference light LR2 are irradiated substantially in the same axis and with the same spot size, the coupling efficiency Gd of the detection light LD1 and the coupling efficiency Gr of the reference light LR1 are approximately. Will be equal. Moreover, since the detection light LD1 and the reference light LR1 have relatively close peak wavelengths, the reflectance Rd of the detection light LD1 and the reflectance Rr of the reference light LR1 are substantially equal.

  Therefore, the following (Expression 4) is derived by taking the ratio of (Expression 1) and (Expression 3).

  (Formula 4) Pd / Pr = Z × Aad

  Here, Z is a constant term and is represented by (Equation 5).

  (Formula 5) Z = (Pd0 / Pr0) × (Td / Tr) × (Ivd / Ivr)

  The light energies Pd0 and Pr0 are predetermined as initial outputs of the detection light source 21 and the reference light source 22, respectively. Further, the transmittance Td of the reflected detection light LD3 and the transmittance Tr of the reflected reference light LR3 are determined in advance by the transmission characteristics of the detection filter 61 and the reference filter 62, respectively. The light receiving sensitivity Ivd of the reflected detection light LD3 and the light receiving sensitivity Ivr of the reflected reference light LR3 are determined in advance by the light receiving characteristics of the detection light receiving element 31 and the reference light receiving element 32, respectively. Therefore, Z shown in (Expression 5) can be regarded as a constant.

  The signal processing circuit 80 calculates the light energy Pd of the reflected detection light LD3 based on the detection signal, and calculates the light energy Pr of the reflected reference light LR3 based on the reference signal. Specifically, the signal level (voltage level) of the detection signal corresponds to the light energy Pd, and the signal level (voltage level) of the reference signal corresponds to the light energy Pr.

  Therefore, the signal processing circuit 80 can calculate the absorption rate Aa of the moisture contained in the target object 2 based on (Equation 5). Thereby, the signal processing circuit 80 can calculate the water content based on (Equation 2).

[Effects, etc.]
As described above, the optical component sensor 1 according to the present embodiment includes the detection light source 21 that emits the detection light LD1 including the absorption wavelength due to the predetermined component, and the reference light LR1 that does not include the absorption wavelength due to the component. Light source 22, housing 10 that houses detection light source 21 and reference light source 22, and concave reflection mirror 41 that is housed in housing 10 and reflects detection light LD 1 and reference light LR 1. The outgoing detection light LD2 that is at least a part of the detection light LD1 reflected by the mirror 41 and the outgoing reference light LR2 that is at least a part of the reference light LR1 reflected by the concave reflection mirror 41 The light projecting unit 40 that emits toward the object 2 located at the position and the reflection detection light LD3 that is at least part of the emission detection light LD2 reflected by the object 2 are received. The detection light receiving element 31 housed in the housing 10 and the reflected reference light LR3 that is at least a part of the outgoing reference light LR2 reflected by the object 2 are received in the housing 10 for reference. Based on the light receiving element 32, the detection signal corresponding to the reflected detection light LD3 output from the detection light receiving element 31, and the reference signal corresponding to the reflected reference light LR3 output from the reference light receiving element 32 2, the detection light source 21 is disposed at a position different from the optical path of the reference light reflected by the concave reflection mirror 41, and the reference light source 22 is concave reflection. The emission detection light LD2 and the emission reference light LR2 are arranged at different positions on the optical path of the detection light reflected by the mirror 41. Degree distribution is substantially the same.

  Thereby, the light source 21 for a detection and the light source 22 for a reference are arrange | positioned in the position different from the optical path of a mutual light. That is, the detection light source 21 and the reference light source 22 do not receive mutual positional interference. For this reason, it is possible to suppress loss of optical energy of the emission detection light LD2 and the emission reference light LR2. Further, since the optical axes of the emission detection light LD2 and the emission reference light LR2 are parallel, each light can be irradiated to substantially the same position of the object 2 without depending on the distance to the object 2. . Furthermore, since the intensity distributions of the emission detection light LD2 and the emission reference light LR2 substantially match, noise components common to the emission detection light LD2 and the emission reference light LR2 can be canceled with high accuracy. As described above, according to the optical component sensor 1 according to the present embodiment, the component detection accuracy can be increased.

  For example, the concave reflecting mirror 41 includes one concave reflecting surface 42 that reflects the detection light LD1 and the reference light LR1.

  Thereby, since one reflective surface 42 reflects both the detection light LD1 and the reference light LR1, the configuration of the concave reflection mirror 41 can be simplified. For this reason, for example, the characteristic variation at the time of mass production can be suppressed, so that the component detection accuracy can be increased.

  Also, for example, the component is moisture.

  Thereby, the water | moisture content contained in the target object 2 can be detected accurately.

(Modification 1)
Below, the optical component sensor which concerns on the modification 1 is demonstrated. The optical component sensor according to this modification is different from the optical component sensor according to the embodiment in the configuration of the light projecting unit 40. For this reason, below, it demonstrates focusing on the structure of a light projection part, and abbreviate | omits or simplifies description about another structure. The same applies to Modifications 2 and 3 to be described later.

  FIG. 10 is a diagram illustrating a configuration of the light projecting unit 140 according to the present modification. In FIG. 10, the shaded portions of the sparse dots schematically show the irradiation areas of the detection light LD1 and the emission detection light LD2. The portions with dense dot shading schematically show the irradiation areas of the reference light LR1 and the outgoing reference light LR2. Solid arrows indicate the optical axes of the detection light LD1 and the emission detection light LD2. Dashed arrows indicate the optical axes of the reference light LR1 and the outgoing reference light LR2. These also apply to FIGS. 11 and 12 described later.

  As shown in FIG. 10, the light projecting unit 140 includes a concave reflecting mirror 141. The concave reflecting mirror 141 has a first reflecting surface 142 and a second reflecting surface 143.

  The first reflecting surface 142 is a concave reflecting surface that reflects the detection light LD1. At least a part of the detection light LD1 reflected by the first reflecting surface 142 is the emission detection light LD2. The first reflecting surface 142 is, for example, a part of a rotating paraboloid or a rotating ellipsoid. In the present modification, the first reflecting surface 142 is a paraboloid of revolution, and the detection light source 21 is disposed at the focal point. Thus, the first reflecting surface 142 reflects the detection light LD1 as the emission detection light LD2 so as to be parallel to the axis of the paraboloid of revolution.

  The second reflecting surface 143 is a concave reflecting surface that reflects the reference light LR1. At least a part of the reference light LR1 reflected by the second reflecting surface 143 is the outgoing reference light LR2. The second reflecting surface 143 is, for example, a part of a rotating paraboloid or a rotating ellipsoid. In the present modification, the second reflecting surface 143 is a paraboloid of revolution, and the reference light source 22 is disposed at the focal point. Accordingly, the second reflecting surface 143 reflects the reference light LR1 as the outgoing reference light LR2 so as to be parallel to the axis of the paraboloid of revolution.

  As shown in FIG. 10, the first reflecting surface 142 and the second reflecting surface 143 are connected to be convex at the approximate center of the concave reflecting mirror 141. That is, the first reflecting surface 142 and the second reflecting surface 143 are not continuously inclined.

  In this modification, the concave reflecting mirror 141 is formed such that the axis of the first reflecting surface 142 and the axis of the second reflecting surface 143 are parallel. As a result, the axes of the outgoing detection light LD2 and the outgoing reference light LR2 become parallel.

  In this modification, unlike the embodiment, the detection light LD1 and the reference light LR2 do not intersect. Therefore, the optical axis of the outgoing detection light LD2 is located on the detection light source 21 side, and the optical axis of the outgoing reference light LR2 is located on the reference light source 22 side. Therefore, the intensity distributions of the emission detection light LD2 and the emission reference light LR2 according to this modification are obtained by horizontally inverting the intensity distribution shown in FIG.

  As described above, in the optical component sensor according to this modification, the concave reflection mirror 141 includes the concave first reflection surface 142 that reflects the detection light LD1 and the concave second reflection surface 143 that reflects the reference light LR1. And have.

  Thereby, since the concave reflecting mirror 141 has two reflecting surfaces, it can be formed in an appropriate shape suitable for each of the detection light LD1 and the reference light LR1. Therefore, it is possible to further improve the accuracy of matching the intensity distributions of the emission detection light LD2 and the emission reference light LR2. Therefore, the component detection accuracy can be increased.

(Modification 2)
Next, an optical component sensor according to Modification 2 will be described.

  In the above embodiment and the first modification, the example in which the optical axes of the outgoing detection light LD2 and the outgoing reference light LR2 that are light reflected by the concave reflecting mirror 41 or 141 are parallel is shown. There may be a case where the optical axes of the detection light and the reference light reflected by the mirror 41 or 141 are not parallel. The light projecting unit according to this modification includes an optical lens for making the optical axis of the light reflected by the concave reflecting mirror 41 or 141 parallel.

  FIG. 11 is a diagram illustrating a configuration of the light projecting unit 240 according to the present modification. As shown in FIG. 11, the light projecting unit 240 includes a concave reflecting mirror 141 and an optical lens 244.

  The concave reflecting mirror 141 is substantially the same as the first modification, but the optical axes of the reflected detection light and reference light are not parallel. As shown in FIG. 11, the optical axis of the detection light LD1a reflected by the first reflection surface 142 and the optical axis of the reference light LR1a reflected by the second reflection surface 143 are not parallel but slightly shifted. ing.

  As shown in FIG. 11, the optical lens 244 is disposed in front of the concave reflecting mirror 141. Here, “front” is the direction in which light is reflected by the concave reflecting mirror 141. Specifically, the optical lens 244 is disposed on the optical path of the detection light LD1a and the reference light LR1a reflected by the concave reflecting mirror 141. The optical lens 244 may be fixed inside the housing 10 or may be fixed in an opening provided on the outer wall of the housing 10.

  The optical lens 244 emits the emission detection light LD2 and the emission reference light LR2 by transmitting the detection light LD1a and the reference light LR1a reflected by the concave reflecting mirror 141 with their respective optical axes parallel to each other. The optical lens 244 is a collimator lens, for example, and emits incident light as parallel light.

  The optical lens 244 is, for example, a resin convex lens, but is not limited thereto. For example, the optical lens 244 may be a double-sided convex lens or a single-sided convex lens. The optical lens 244 is not limited to resin, and may be formed from glass.

  As described above, in the optical component sensor according to this modification, the light projecting unit 240 further includes the optical lens 244 disposed in front of the concave reflection mirror 141, and the optical lens 244 is the concave reflection mirror 141. The detection light LD1a and the reference light LR1a reflected by the light are transmitted through the respective optical axes in parallel, so that the emission detection light LD2 and the emission reference light LR2 are emitted.

  Thereby, even when the optical axes of the detection light LD1a and the reference light LR1a reflected by the concave reflecting mirror 141 are not parallel, the optical axes are parallel by passing the optical lens 244 through the detection light LD1a and the reference light LR1a. The emission detection light LD2 and the emission reference light LR2 can be emitted. Therefore, the component detection accuracy can be increased.

(Modification 3)
Next, an optical component sensor according to Modification 3 will be described.

  In the above-described embodiment and Modification 1, an example in which the intensity distributions of the outgoing detection light LD2 and the outgoing reference light LR2, which are light reflected by the concave reflecting mirror 41 or 141, are substantially the same is shown. There may be a case where there is a large difference in intensity distribution between the detection light and the reference light reflected by the mirror 41 or 141. The light projecting unit according to this modification includes an aperture for substantially matching the intensity distribution of the reflected light from the concave reflecting mirror 41 or 141.

  FIG. 12 is a diagram illustrating a configuration of the light projecting unit 340 according to the present modification. As shown in FIG. 12, the light projecting unit 340 includes a concave reflecting mirror 141 and an aperture 345.

  The concave reflecting mirror 141 is substantially the same as in the first modification, but the intensity distributions of the reflected detection light and reference light do not match. As shown in FIG. 12, the intensity distribution of the detection light LD1b reflected by the first reflecting surface 142 does not match the intensity distribution of the reference light LR1b reflected by the second reflecting surface 143.

  As shown in FIG. 12, the aperture 345 is disposed in front of the concave reflecting mirror 141. Specifically, the aperture 345 is disposed on the optical path of the detection light LD1b and the reference light LR1b reflected by the concave reflecting mirror 141. The aperture 345 is fixed inside the housing 10. Alternatively, the aperture 345 may be a part of the housing 10. In other words, the opening for emitting the emission detection light LD2 and the emission reference light LR2 from the housing 10 to the outside may be the opening of the aperture 345.

  The aperture 345 emits the outgoing detection light LD1 and the outgoing reference light LR2 by shielding a part of each of the detection light LD1b and the reference light LR1b reflected by the concave reflecting mirror 141 and transmitting the remaining light. Specifically, the aperture 345 blocks light in the portions of the detection light LD1b and the reference light LR1b whose intensity distributions do not match each other. For example, the aperture 345 blocks the ambient light of the detection light LD1b and the reference light LR1b. The ambient light of the detection light LD1b is, for example, light at a portion away from the optical axis in a cross section orthogonal to the optical axis of the detection light LD1b. The ambient light is, for example, a portion lower than a predetermined ratio of the light intensity on the optical axis. The same applies to the ambient light of the reference light LR1b.

  The aperture 345 is a light-shielding member provided with an opening (slit) having a predetermined diameter, for example. The opening is circular, for example, but may be rectangular or square.

  As described above, in the optical component sensor according to the present modification, for example, the light projecting unit 340 further includes the aperture 345 disposed in front of the concave reflecting mirror 141, and the aperture 345 includes the concave reflecting mirror 141. The emission detection light LD2 and the emission reference light LR2 are emitted by shielding a part of each of the detection light LD1b and the reference light LR1b reflected by the light and passing the rest.

  As a result, even if the intensity distributions of the detection light LD1b and the reference light LR1b reflected by the concave reflecting mirror 141 do not match, the intensity distributions substantially match by allowing the detection light LD1b and the reference light LR1b to pass through the opening of the aperture 345. The outgoing detection light LD2 and the outgoing reference light LR2 can be emitted. Therefore, the component detection accuracy can be increased.

(Other)
As described above, the optical component sensor according to the present invention has been described based on the above-described embodiment and its modifications. However, the present invention is not limited to the above-described embodiment.

  For example, in the above first to third modifications, an example in which the concave reflecting mirror 141 is formed from one component has been described. It may be formed in combination with parts.

  For example, the concave reflecting mirror 41 may be a beam splitter (half mirror) or the like, and may separate a part of the detection light LD1 and the reference light LR1. For example, the separated part of the detection light LD1 may enter the reference light receiving element 32 as monitor light, and the separated part of the reference light LR1 may enter the detection light receiving element 31 as monitor light. . Deterioration of the detection light source 21 and the reference light source 22 can be detected using the monitor light.

  For example, in the above-described embodiment, the optical component sensor 1 detects moisture as a component included in the object 2, but is not limited thereto. For example, the optical component sensor 1 may detect alcohol or oil. For example, the optical component sensor 1 may irradiate the object 2 with detection light including an absorption wavelength due to alcohol to be detected and reference light not including an absorption wavelength due to alcohol. Moreover, the optical component sensor 1 may detect not only a liquid component but gas components, such as a carbon dioxide, for example.

  In addition, the embodiment can be realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present invention, or a form obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Optical component sensor 2 Object 10 Case 21 Light source for detection (1st light source)
22 Light source for reference (second light source)
31 Light-receiving element for detection (first light-receiving element)
32 Light receiving element for reference (second light receiving element)
40, 140, 240, 340 Projection unit 41, 141 Concave reflection mirror 42 Reflection surface 70 Control circuit 80 Signal processing circuit 142 First reflection surface 143 Second reflection surface 244 Optical lens 345 Aperture LD1, LD1a, LD1b Detection light LD2 Emission Detection light LD3 Reflection detection light LR1, LR1a, LR1b Reference light LR2 Emission reference light LR3 Reflection reference light

Claims (6)

A first light source that emits detection light including an absorption wavelength due to a predetermined component;
A second light source that emits reference light that does not include an absorption wavelength by the component;
A housing for housing the first light source and the second light source;
An exit detection light that is housed in the housing and has a concave reflection mirror that reflects the detection light and the reference light, and that is at least part of the detection light reflected by the concave reflection mirror, and the concave reflection mirror A light projecting unit that emits outgoing reference light, which is at least part of the reflected reference light, toward an object located outside the housing;
A first light receiving element housed in the housing for receiving reflected detection light that is at least part of the emission detection light reflected by the object;
A second light receiving element housed in the housing for receiving reflected reference light that is at least part of the outgoing reference light reflected by the object;
The component included in the object based on a detection signal corresponding to the reflected detection light output from the first light receiving element and a reference signal corresponding to the reflected reference light output from the second light receiving element. And a signal processing circuit for detecting
The first light source is disposed at a position different from the optical path of the reference light reflected by the concave reflecting mirror,
The second light source is disposed at a position different from the optical path of the detection light reflected by the concave reflecting mirror,
The optical component sensor in which the outgoing detection light and the outgoing reference light have parallel optical axes and substantially coincide with each other in intensity distribution in a cross section orthogonal to the optical axis. The optical component sensor according to claim 1, wherein the concave reflection mirror has one concave reflection surface that reflects the detection light and the reference light. The concave reflecting mirror is
A concave first reflecting surface that reflects the detection light;
The optical component sensor according to claim 1, further comprising a concave second reflecting surface that reflects the reference light. The light projecting unit further includes an optical lens disposed in front of the concave reflecting mirror,
The optical lens emits the emission detection light and the emission reference light by transmitting the detection light and the reference light reflected by the concave reflecting mirror with their respective optical axes parallel to each other. The optical component sensor according to any one of the above. The light projecting unit further includes an aperture disposed in front of the concave reflecting mirror,
5. The aperture emits the emission detection light and the emission reference light by shielding a part of each of the detection light and the reference light reflected by the concave reflecting mirror and allowing the rest to pass therethrough. The optical component sensor according to any one of the above. The optical component sensor according to claim 1, wherein the component is moisture.

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