WO2018155290A1

WO2018155290A1 - Optical type component sensor

Info

Publication number: WO2018155290A1
Application number: PCT/JP2018/005162
Authority: WO
Inventors: 弘貴松浪; 渡部　祥文; 徹馬場
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2017-02-27
Filing date: 2018-02-15
Publication date: 2018-08-30
Also published as: JPWO2018155290A1; CN110291380A

Abstract

An optical type component sensor (1) according to the present invention is provided with: a light source (21) which generates outgoing light (LR1) including an absorption wavelength of a certain component; a casing (10) accommodating the light source (21); a light projecting unit (22) which emits light toward an object (2) located outside the casing (10); a light receiving lens (31) which condenses light reflected by the object 2; a first filter (32a) which transmits light in a first wavelength and reflects light in a second wavelength, from among the light condensed by the light receiving lens (31); a second filter (32b) which transmits light in the second wavelength reflected by the first filter (32a), from among the light condensed by the light receiving lens (31); a first light receiving element (33a) which is accommodated in the casing (10), receives detection light that has been transmitted through the first filter (32a), and converts the same into a first electrical signal; and a second light receiving element (33b) which is accommodated in the casing (10), receives reference light that has been additionally reflected by the first filter (32a) and has been transmitted through the second filter (32b), and converts the same into a second electrical signal.

Description

Optical component sensor

The present invention relates to an optical component sensor.

BACKGROUND Conventionally, a photoelectric sensor capable of determining a detection object located at a long distance is known (see, for example, Patent Document 1). The reflection type photoelectric sensor described in Patent Document 1 includes a light projecting unit that emits two light beams having different wavelengths to a detection object, a reflector that reflects one of the two light beams, a detection object or a reflection object. And a light receiving unit for receiving the light reflected by the plate. According to the reflection type photoelectric sensor, the presence or absence of a detected object can be known by processing the light reception signal output from the light reception unit.

JP-A-8-255533

In the reflection type photoelectric sensor described in Patent Document 1, the light emitting unit includes two light emitting elements whose optical axes coincide with each other, and the two light emitting elements are arranged such that their emission faces are in opposite directions. There is. The light emitted from one of the two light emitting elements is reflected by the reflection plate and emitted to the outside through the light projection lens. The light emitting element is disposed in the reflection direction of the reflecting plate, and the light reflected by the reflecting plate is blocked by the light emitting element, and light energy emitted to the outside is reduced. This reduces the detection accuracy of the component object.

Then, an object of this invention is to provide the optical component sensor which can increase the light radiate | emitted outside outside and can acquire reflected light stably.

An optical component sensor according to the present invention emits light toward a light source that emits emitted light including an absorption wavelength of a predetermined component, a housing that houses the light source, and an object located outside the housing. Of the first wavelength band among the light condensed by the light receiving lens, and the light of the second wavelength band is reflected. A second filter that transmits the light of the second wavelength band among the light collected by the light receiving lens, and the detection light received in the housing and transmitted through the first filter; And a second light receiving element which is accommodated in the housing, receives the reference light transmitted through the second filter, and converts the received reference light into a second electric signal.

According to the present invention, the light emitted to the outside is increased and the reflected light is stably acquired.

FIG. 1 is a schematic configuration view showing a configuration of the optical component sensor according to the embodiment. FIG. 2 is a block diagram showing a functional configuration of the optical component sensor according to the embodiment. FIG. 3 is a diagram showing an absorption spectrum of water and water vapor. FIG. 4 is a schematic configuration view showing a configuration of a light projecting optical module according to the embodiment. FIG. 5 is a schematic configuration view showing a configuration of Modification Example 1 of the optical component sensor according to the embodiment. FIG. 6 is a schematic configuration view showing a configuration of Modification 2 of the light receiving optical system module according to the embodiment.

Below, the optical component sensor which concerns on embodiment of this invention is demonstrated in detail using drawing. Each of the embodiments described below shows a preferable specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangements 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 components in the following embodiments, components that are not described in the independent claims indicating the highest concept of the present invention are described as optional components.

Further, each drawing is a schematic view, and is not necessarily illustrated exactly. Therefore, for example, the scale and the like do not necessarily match in each figure. Further, in each of the drawings, substantially the same configuration is given the same reference numeral, and overlapping description will be omitted or simplified.

Embodiment
[Overview]
First, an outline of the optical component sensor 1 according to the embodiment will be described.

The optical component sensor 1 irradiates one object (emission light LR1) onto the object 2 and receives the reflection light LR2 (reflection detection light LR21 and reflection reference light LR22) from the object 2, thereby the object It is a non-contact type optical component sensor which detects the component contained in 2. In the present embodiment, as shown in FIG. 1, the optical component sensor 1 detects moisture contained in the object 2 located at a position separated by the space 3.

The object 2 is, for example, clothing if not particularly limited. As objects 2 other than clothing, bedding, such as a sheet and a pillow cover, may be mentioned. For example, by attaching the optical component sensor 1 to a clothes dryer or the like, the degree of dryness of clothes can be confirmed. As a result, it is possible to suppress the occurrence of pain and the like of clothes due to excessive drying.

The space 3 is a space (free space) between the optical component sensor 1 and the object 2 and contains moisture (water vapor). The space 3 is an external space of the case 10 of the optical component sensor 1.

As shown in FIG. 1, the optical component sensor 1 includes a housing 10, a light projecting optical module 20, and a light receiving optical module 30. The projection optical module 20 has a light source 21 and a projection lens 22. The light receiving optical module 30 has a light receiving lens 31, a detection band pass filter 32a, a reference band pass filter 32b, a detection light receiving element 33a, and a reference light receiving element 33b.

In the present specification, with reference to the light projection lens 22, the direction in which the light source 21 emits light (X-axis positive direction in the figure) is "forward" and the opposite direction (X-axis negative direction in the figure) is "rearward "

Further, as shown in FIG. 2, the optical component sensor 1 includes a control circuit 40 and a signal processing circuit 50.

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

[Case]
The housing 10 is a housing that accommodates the light source 21. As shown in FIG. 1, the light receiving lens 31, the detection band pass filter 32a, the reference band pass filter 32b, the detection light receiving element 33a, and the reference light receiving element 33b are further housed in the housing 10 There is.

The housing 10 is formed of a light shielding material. Thereby, it can suppress that external light injects in the housing | casing 10. As shown in FIG. Specifically, the housing 10 has a light shielding property with respect to light received by the light receiving element for detection 33a and the light receiving element for reference 33b. More specifically, the housing 10 has a light shielding property with respect to the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22), and is formed of, for example, a resin material or a metal material.

Further, an opening is provided in the outer wall of the housing 10, and the light projection lens 22 and the light receiving lens 31 are attached to the opening.

[Projector optical module]
The light projecting optical module 20 is an optical system that emits light for detecting a component, and includes a light source 21 and a light projecting lens 22.

[light source]
The light source 21 is an example of a light source that emits the emitted light LR1 including the absorption wavelength of the component to be detected. Specifically, the light source 21 targets the light including the first wavelength band in which the absorption by water is larger than the predetermined value and the light including the second wavelength band in which the absorption by water is the predetermined value or less It emits toward the thing 2.

The light source 21 is, for example, an LED (Light Emitting Diode) light source that emits continuous light having a peak wavelength on the second wavelength band side including a first wavelength band forming detection light and a second wavelength band forming reference light. is there. Specifically, the light source 21 is an LED light source made of a compound semiconductor.

FIG. 3 is a diagram showing an absorption spectrum of water and water vapor. As shown in FIG. 3, the moisture has absorption peaks at wavelengths of about 1450 nm and about 1900 nm. Water vapor has an absorption peak at a wavelength slightly lower than the absorption peak of water, specifically at a wavelength of about 1350 nm to about 1400 nm and about 1800 nm to about 1900 nm.

For this reason, a wavelength band where the light absorbance of water is high is selected as the first wavelength band that forms detection light, and a wavelength band where the absorbance of water is smaller than the first wavelength band is selected as the second wavelength band that makes reference light. select. Then, the average wavelength of the second wavelength band is made longer than the average wavelength of the first wavelength body.

In FIG. 3, the absorbance of water vapor has a peak (first peak P1) at a wavelength of about 1350 nm to 1400 nm and a peak (second peak P2) at a wavelength of about 1800 nm to 1900 nm. For example, when the first peak P1 is used as a reference, the center wavelength of the first wavelength band is 1450 nm, the center wavelength of the second wavelength band is between the first peak P1 and the second peak P2, The absorbance is set to a wavelength smaller than a predetermined value. Specifically, the central wavelength of the second wavelength band may be within 1.2 times the central wavelength of the first wavelength band. The central wavelength of the second wavelength band is within 1450 nm × 1.2 ≒ 1740 nm. Specifically, the central wavelength of the second wavelength band is 1700 nm.

As described above, since the light source 21 irradiates the light including the first wavelength band and the second wavelength band continuously, the object 2 includes the detection light including the first wavelength band where the absorption by water is large; The reference light including the second wavelength band in which the absorption by water is smaller than the first wavelength band and the absorption by water vapor is scarce is irradiated.

The light source 21 is disposed in the housing so as to face the light projection lens 22 on the optical axis of the light source 21.

[Projector lens]
The light projection lens 22 is an example of a light projection unit that emits the emitted light LR <b> 1 emitted by the light source 21 toward the object 2.

As shown in FIG. 1 or 4, the light projection lens 22 is fixed to the housing 10, for example, so that the focal point is located on the optical axis of the light source 21.

The light projection lens 22 is made of a transparent synthetic resin such as acrylic, and is molded in a substantially inverted truncated cone shape which is a shape in which the width diameter is gradually expanded in the emission direction. A light source 21 is disposed at the end of the light emitting lens 22 in the negative X-axis direction. The light projection lens 22 condenses the emitted light LR1 from the light source 21 and irradiates it in front of the light projection lens 22 as a bundle of light of a constant intensity.

The peripheral wall 221 of the light projection lens 22 is molded in a curved shape which is slightly expanded outward from the end in the X-axis negative direction of the light projection lens 22 to the front surface 222. A front surface 222 which is an exit surface of the light projection lens 22 is formed as a flat portion. A recess 223 is formed at the end of the light emitting lens 22 in the negative X-axis direction so as to surround the light source 21. The recess 223 has a convex bottom surface 223 a on the light source 21 side and a side peripheral surface 223 b formed so as to surround the bottom surface 223 a. The side peripheral surface 223 b is molded in a tapered shape in which the hole diameter is gradually narrowed from the end of the light emitting lens 22 in the negative direction of the X axis toward the front. Thereby, the recessed part 223 becomes a tapered substantially cylindrical shape.

The hole diameter, height, and taper of the recess 223 are appropriately designed according to the dimensions of the light source 21 and the dimensions of the refractive index and the outer shape according to the material of the light projection lens 22.

Of the light emitted from the light source 21, light traveling toward the bottom surface 223 a of the concave portion 223 is incident on the convex curved surface of the bottom surface 223 a and is converged to go straight inside the projection lens 22 and passes through the front surface 222 of the projection lens 22. It is irradiated towards the object 2.

Further, among the light emitted from the light source 21, light traveling toward the side peripheral surface 223 b of the recess 223 is incident on the side peripheral surface 223 b at the light projection lens 22 at a total reflection angle or less according to the refractive index of the light projection lens 22. Do. The light entering the light projection lens 22 from the side peripheral surface 223 b is totally reflected at a total reflection angle or more with respect to the peripheral wall 221 of the light projection lens 22, passes through the light projection lens 22 and travels from the front surface 222 to the object 2 It is irradiated. At this time, the emitted light LR1 emitted from the light projection lens 22 is irradiated with the object 2 as substantially parallel light.

In the light projection lens 22, the bottom surface 223 a of the concave portion 223 has a convex shape, so that the light passing through the bottom surface 223 a of the concave portion 223 is converged to some extent on the convex surface and irradiated from the front surface 222. As a result, a large amount of light (that is, intensity) can be irradiated to the detection target area RA1 where it is desired to detect the amount of water in the object 2, and the light reception sensitivity can be increased.

Although the front surface 222 of the light projection lens 22 is a flat portion, only the outer peripheral portion may be a flat portion, and the central portion may be a convex lens shape. Thereby, the light converged on the bottom surface 223a of the concave portion 223 is also converged on the front surface 222 and is irradiated to the object 2, so that a larger amount of light can be irradiated to the detection target area RA1 and the light receiving sensitivity is increased. be able to.

[Receiver optical module]
As shown in FIGS. 1 and 2, the light receiving optical module 30 is an optical system that measures part of the light emitted from the light source 21 and reflected by the object 2 to measure the water content. It is. The light receiving optical module 30 includes a light receiving lens 31, a detection band pass filter 32a, a reference band pass filter 32b, a detection light receiving element 33a, and a reference light receiving element 33b.

[Receiver lens]
The light receiving lens 31 is an example of a light receiving lens for condensing the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22) reflected by the object 2 on the light receiving element 33a for detection and the light receiving element 33b for reference. . The light receiving lens 31 is, for example, a condensing lens. The light receiving lens 31 is disposed on the optical axis of the light receiving element 33a for detection, and is fixed to the housing 10 so that the focal point is at a position farther than the light receiving surface of the light receiving element 33a for detection. The light receiving lens 31 is a resin-made convex lens in the present embodiment, but is not limited to this.

Band pass filter for detection
The detection band pass filter 32a transmits the reflected detection light LR21 out of the reflected light LR2 collected by the light receiving lens 31, makes it incident on the light receiving element 33a for detection, and reflects light in wavelength bands other than the reflected detection light LR21. It is an example of a 1st filter.

In the present embodiment, as shown in FIG. 1, the detection band pass filter 32a is provided between the light receiving lens 31 and the detection light receiving element 33a, and is located on the optical axis of the reflected detection light LR21. It is disposed to be inclined with respect to the lens 31. At this time, as long as the reflected reference light LR22 can be reflected by the detection band pass filter 32a and incident on the reference light receiving element 33b, the inclination direction or angle of the detection band pass filter 32a does not matter.

By this arrangement, the detection band pass filter 32a transmits light which is the peak wavelength of the reflected detection light LR21 and reflects light in a peak wavelength band other than the reflected detection light LR21.

The detection band pass filter 32a is configured to be able to reflect light by being provided by laminating dielectric films different in refractive index formed of, for example, SiO ₂ or the like.

Band pass filter for reference
The reference band pass filter 32b is an example of a second filter provided on the optical path of the reflected reference light LR22 incident on the reference light receiving element 33b.

In the present embodiment, as shown in FIG. 1, the reference band pass filter 32b is provided between the detection band pass filter 32a and the reference light receiving element 33b, with respect to the optical axis of the reflected reference light LR22. It is arranged substantially vertically.

Note that the installation angle of the reference band pass filter 32b is set so that the peak wavelength band to be the reflected reference light LR22 of the light reflected by the detection band pass filter 32a can be transmitted. Design change is possible as long as it is disposed.

The reference band pass filter 32b transmits only the reflected reference light LR22, and absorbs or reflects the reflected detection light LR21. Therefore, the reflection detection light LR21 is absorbed or reflected by the reference band pass filter 32b and hardly reaches the reference light receiving element 33b.

[Light receiving element for detection]
The detection light receiving element 33a is an example of a first light receiving element that receives the reflection detection light LR21 transmitted through the detection band pass filter 32a among the reflection light LR2 which is at least a part of the light reflected by the object 2 is there. The light receiving element for detection 33a photoelectrically converts the received reflected detection light LR21 to generate a detection signal which is an electrical signal according to the amount (ie, intensity) of the received reflected detection light. The generated detection signal is output to the signal processing circuit 50.

It is preferable that the light receiving element for detection 33a have a light receiving sensitivity sufficiently strong with respect to the peak wavelength of the reflected detection light LR21. Therefore, the light receiving element for detection 33a can receive the reflected detection light LR21 and can generate an electrical signal (detection signal) according to the amount of received light.

The detection light receiving element 33 a is accommodated in the housing 10. The light receiving element 33a for detection is disposed on the optical axis of the light receiving lens 31, and on the optical axis, as shown in FIG. That is, when the distance d ₁ between the light receiving lens 31 and the light receiving element for detection 33 a and the focal distance f ₁ of the light receiving lens 31 are provided, they are arranged so as to satisfy 0 <d ₁ <f ₁ .

As a result, an area RA2 for taking in the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22) as diffused light having a predetermined radius of curvature without being focused on the surface of the light receiving lens 31 is formed. As the radius of curvature of the diffused light increases, the area RA2 for taking in the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22) becomes wider, and the capturing ratio of the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22) increases. Become. That is, the light receiving range can be widened.

At this time, it is preferable that the object 2 be irradiated such that the area for taking in the reflected light LR2 (the reflected detection light LR21 and the reflected reference light LR22) overlaps with at least a part of the detection target area RA1.

The light receiving element for detection 33a is, for example, a photodiode, but is not limited to this. For example, the light receiving element for detection 33a may be a phototransistor or an image sensor. The detection light receiving element 33a and the reference light receiving element 33b may use different areas of one image sensor.

[Light receiving element for reference]
The reference light receiving element 33b is a reflected light LR22 reflected by the detection band pass filter 32a and transmitted through the reference band pass filter 32b among the reflected light LR2 which is at least a part of the light reflected by the object 2. It is an example of the 2nd light receiving element which light-receives. The reference light receiving element 33 b photoelectrically converts the received reflected reference light LR <b> 22 to generate a reference signal which is an electrical signal corresponding to the amount of received light of the reflected reference light LR <b> 22. The generated reference signal is output to the signal processing circuit 50.

The reflected reference light LR22 is light in which the outgoing light LR1 is reflected by the object 2. The peak wavelength of the reflected reference light LR22 is measured as about 1570 nm in the present embodiment.

The reference light receiving element 33 b is accommodated in the housing 10. The reference light receiving element 33 b is disposed substantially parallel to the optical axis of the light receiving lens 31. The reference light receiving element 33b is disposed on the optical axis of the reflected reference light LR22 so that the focal position of the received light is closer to the reference band pass filter 32b than the light receiving surface. That is, when the distance d ₂ between the light receiving lens 31 and the reference light receiving element 33 b and the focal distance f ₂ of the light receiving lens 31 are provided, they are arranged so as to satisfy 0 <d ₂ <f ₂ .

The reference light receiving element 33b is, for example, a photodiode, but is not limited to this. For example, the reference light receiving element 33b may be a phototransistor or an image sensor.

[Control circuit]
The control circuit 40 controls the emitted light LR1 of the light source 21. Specifically, the control circuit 40 can independently control light emission and extinguishment of the light source 21.

For example, the control circuit 40 causes the light source 21 to emit light. Specifically, the control circuit 40 causes the light source 21 to emit light with a pulse waveform. For example, the control circuit 40 outputs a pulse signal of a predetermined frequency (for example, 1 kHz) to the light source 21. For example, the on-duty ratio of the light source 21 is a pulse signal of 50% or less.

Although not shown in FIG. 1, the control circuit 40 may be housed in the housing 10 or may be attached to the outer surface of the housing 10. Alternatively, the control circuit 40 may have a communication function such as wireless communication, and may transmit a pulse signal for control to the light source 21.

The control circuit 40 includes, for example, a drive circuit and a microcontroller. The control circuit 40 has a non-volatile memory in which a control program of a light source is stored, a volatile memory which is a temporary storage area for executing a program, an input / output port, a processor for executing the program, and the like.

[Signal processing circuit]
The signal processing circuit 50 is a target based on the detection signal corresponding to the reflection detection light LR21 output from the detection light receiving element 33a and the reference signal corresponding to the reflection reference light LR22 output from the reference light receiving element 33b. The component which the thing 2 contains is calculated. Specifically, the signal processing circuit 50 detects the amount of water contained in the object 2 based on the ratio (energy ratio) of the voltage level of the detection signal to the voltage level of the reference signal. A specific method of detecting (calculating) the amount of water will be described later.

The signal processing circuit 50 may be housed in the housing 10 or may be attached to the outer surface of the housing 10. Alternatively, the signal processing circuit 50 may have a communication function such as wireless communication, and may receive output signals from the detection light receiving element 33a and the reference light receiving element 33b.

The signal processing circuit 50 is, for example, a microcontroller. The signal processing circuit 50 has a non-volatile memory in which a signal processing program is stored, a volatile memory which is a temporary storage area for executing a program, an input / output port, a processor for executing the program, and the like.

[Signal processing (detection processing)]
Subsequently, signal processing (component calculation processing) by the signal processing circuit 50 will be described.

In the present embodiment, the signal processing circuit 50 detects the amount of components contained in the object 2 by comparing the light energy Pd of the reflected detection light LR21 with the light energy Pr of the reflected reference light LR22. The light energy Pd corresponds to the intensity of the detection signal output from the detection light receiving element 33a, and the light energy Pr corresponds to the intensity of the reference signal output from the reference light receiving element 33b.

The light energy Pd of the reflected detection light LR21 incident on the detection light receiving element 33a is represented by the following (formula 1).

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

Here, Pd0 is the light energy of the emitted light LR1 emitted by the light source 21. Gd is a coupling efficiency (condensing ratio) of the emitted light LR1 emitted from the light source 21 to the light receiving element 33a for detection. Specifically, Gd corresponds to the ratio of the part of the emitted light LR1 to be a part of the component diffused and reflected by the object 2 (that is, the reflection detection light LR21).

Rd is the reflectance of the emitted light LR1 by the object 2. Td is the transmittance of the reflection detection light LR21 by the detection band pass filter 32a. Ivd is a light receiving sensitivity to the reflection detection light LR21 of the light receiving element 33a for detection.

Aa is an absorptivity of emission light LR1 and reflection detection light LR21 by a component (moisture) contained in the object 2, and is expressed by the following (formula 2).

(Formula 2) Aad = 10- ^{α × C × D}

Here, α is a predetermined absorption coefficient, and specifically, the absorption coefficient of the outgoing light LR1 and the reflection detection light LR21 by the component (moisture). C is the volume concentration of the component (water) 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 outgoing light LR1 and the reflected detection light LR21.

More specifically, in the case of the object 2 in which the water is uniformly dispersed, C is contained in the component of the object 2 when light is incident on the object 2 and is reflected internally and emitted from the object 2 Corresponding to the volume concentration. Further, D corresponds to an optical path length until the light is reflected inside and emitted from the object 2. For example, when the object 2 is a reticulated 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 water contained in the liquid phase covering the solid. Moreover, D is a contribution thickness converted as an average thickness of a liquid phase covering a solid.

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

Similarly, light energy Pr of the reflected reference light LR22 incident on the reference light receiving element 33b is expressed by the following (Expression 3).

(Expression 3) Pr = Pr0 × Gr × Rr × Tr × Ivr

In the present embodiment, the absorptance by water Aad is obtained from the difference between the absorption of the detection light of the first wavelength band by the component (water) contained in the object 2 and the absorption of the reference light of the second wavelength band. . In addition, since it can be considered that reflection reference light LR22 is not substantially absorbed by the component contained in the target object 2, the light corresponded to the absorptance Aa by water so that it may be understood compared with (Formula 1) Is not included in (Equation 3).

In (Expression 3), Pr0 is light energy of the emitted light LR1 emitted by the light source 21. Gr is the coupling efficiency (condensing ratio) of the emitted light LR1 emitted by the light source 21 to the reference light receiving element 33b. Specifically, Gr corresponds to the proportion of the part of the emitted light LR1 that is to be a part of the component diffused and reflected by the object 2 (that is, the reflected reference light LR22).

Rr is the reflectance of the emitted light LR1 by the object 2. Tr is the transmittance of the reflected reference light LR22 by the reference band pass filter 32b. Ivr is the light reception sensitivity of the reference light receiving element 33b to the reflected reference light LR22.

In the present embodiment, since the emitted light LR1 in the light receiving element for detection 33a and the emitted light LR1 in the light receiving element for reference 33b are the same light, the coupling efficiency Gd and the coupling efficiency Gr become substantially equal. Further, since the peak wavelength is also relatively close, the reflectance Rd and the reflectance Rr become substantially equal.

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

(Equation 4) Pd / Pr = Z × Aad

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

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

The light energy Pd0 and Pr0 are each predetermined as an initial output of the light source 21. Further, the transmittance Td of the reflection detection light LR21 and the transmittance Tr of the reflection reference light LR22 are respectively determined in advance by the transmission characteristics of the detection band pass filter 32a and the reference band pass filter 32b. The light reception sensitivity Ivd of the reflection detection light LR21 and the light reception sensitivity Ivr of the reflection reference light LR22 are respectively determined in advance by the light reception characteristics of the detection light receiving element 33a and the reference light receiving element 33b. Therefore, Z shown in (Expression 5) can be regarded as a constant.

The signal processing circuit 50 calculates the light energy Pd of the reflected detection light LR21 based on the detection signal, and calculates the light energy Pr of the reflected reference light LR22 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 50 can calculate the absorptivity Aa of the water contained in the object 2 based on (Expression 5). Thereby, the signal processing circuit 50 can calculate the water content based on (Expression 2).

[Summary]
As described above, the optical component sensor 1 according to the present embodiment includes the light source 21 emitting the emitted light LR1 including the absorption wavelength of the predetermined component, the housing 10 accommodating the light source 21, and the outside of the housing 10 Of the light collected by the light-receiving lens 31 and the light-emitting unit (light-projecting lens 22) that emits light toward the object 2 located on the light-receiving lens 31 that collects the light reflected by the object 2; Among them, the first filter (the detection band pass filter 32a) that transmits the light of the first wavelength band and reflects the light of the second wavelength band, and the light of the second wavelength band of the light collected by the light receiving lens 31 A second filter (reference band pass filter 32b) which transmits light, and a first light receiving element which is received in the housing 10 and receives the detection light transmitted through the first filter and converts it into a first electric signal (light reception for detection Element 33a) and the housing 10, Receiving the reference light transmitted through the filter, it includes a second light receiving element for converting the second electrical signal (see light receiving element 33b), the.

As a result, the amount of reflected light to be received can be increased and the variation in the amount of reflected light can be reduced compared to the case where two light receiving optical modules are used, and stable light reception can be achieved. it can. Furthermore, the concern of the wavelength change due to the deterioration of the light receiving lens can be suppressed, and the component can be detected with high accuracy.

The component is preferably water.

Thus, the water contained in the object 2 can be detected with high accuracy.

(Modification 1)
In the above embodiment, the optical component sensor 1 may be configured to further include the half mirror 34 in the housing 10. In the following description, parts that are the same as those in the above embodiment may be given the same reference numerals and descriptions thereof may be omitted.

Specifically, as shown in FIG. 5, the half mirror 34 is provided between the light receiving lens 31 and the light receiving element for detection 33 a, and is located on the optical axis of the reflected detection light LR 21. And arranged in an inclined manner. At this time, the detection band pass filter 32a is disposed on the optical axis of the reflected light LR2 and the reflected detection light LR21 so as to be substantially perpendicular to the optical axis.

The half mirror 34 emits the reflection detection light LR21 and the reflection reference light LR22 by transmitting and reflecting the reflection light LR2 reflected by the object 2. Specifically, the half mirror 34 transmits part of the incident reflected light LR2 as it is (without substantially changing the traveling direction), and specularly reflects the remaining light. The half mirror 34 reflects and transmits incident light approximately 1: 1, for example. That is, the half mirror 34 emits and reflects 50% of the reflection detection light LR21 and 50% of the reflection reference light LR22 of the light flux of the incident reflection light LR2. Thereafter, of the light transmitted through the half mirror 34, only the reflection detection light LR21 is transmitted through the detection band pass filter 32a, and is guided to the detection light receiving element 33a. Further, among the light reflected by the half mirror 34, only the reflected reference light LR22 passes through the reference band pass filter 32b and is guided to the reference light receiving element 33b to measure the component.

The half mirror 34 is, for example, a translucent plate having a reflective thin film such as a metal thin film or a dielectric multilayer film formed on its surface. As a translucent board | plate material, it forms, for example using glass materials, such as transparent soda glass, or transparent resin materials, such as an acryl (PMMA) and a polycarbonate (PC). The metal thin film is a thin film formed so as to be light transmissive and light reflective using a metal material such as aluminum.

As a result, the reflected light LR2 can be focused on the detection light receiving element 33a and the reference light receiving element 33b in equal amounts, so that the components can be detected with high accuracy.

(Modification 2)
In the above embodiment, the optical component sensor 1 may have condensing lenses 35a and 35b between the respective light receiving elements and the band pass filter. In this case, the light transmitted through the detection band pass filter 32a and the reference band pass filter 32b is collected by the condensing lenses 35a and 35b, respectively, and is received by the detection light receiving element 33a and the reference light receiving element 33b.

Specifically, as shown in FIG. 6, the detection light receiving element 33a and the reference light receiving element 33b are respectively held by the holding portions 36a and 36b. Condenser lenses 35a and 35b having a convex shape toward the band pass filter are disposed on the surfaces of the holding portions 36a and 36b on the detection band pass filter 32a side and the reference band pass filter 32b side. The light transmitted through the detection band pass filter 32a and the reference band pass filter 32b enters the condensing lenses 35a and 35b, and is condensed again by the condensing lenses 35a and 35b.

Therefore, the incident surface of light is expanded by the condenser lenses 35a and 35b, and the amount of light that can be collected is increased, so measurement can be performed with a larger amount of light.

In addition, since the central wavelength of the light transmitted through or reflected by the band pass filter and the half mirror 34 configured of the dielectric multilayer film is likely to change depending on the incident angle, it is difficult to perform high-accuracy measurement. As described above, by providing the condensing lenses 35a and 35b and further condensing the light in the condensing lenses 35a and 35b, it is possible to efficiently receive only a desired wavelength band.

The condenser lenses 35a and 35b are formed of, for example, a transparent resin material. Further, the holding portions 36a and 36b are also formed of the same transparent resin material as the condensing lenses 35a and 35b, so that the optical paths of the light incident on the condensing lenses 35a and 35b are guided to the respective light receiving elements without refraction. It is eaten.

(Others)
As mentioned above, although the optical component sensor 1 which concerns on this invention was demonstrated based on said embodiment and its modification, this invention is not limited to said embodiment and modification.

For example, although the surface on which light is incident is a convex curved surface, the light projection lens 22 is not limited to this, and may be a flat surface or a concave curved surface. If the curvature in the horizontal direction is changed more than in the vertical direction, the change in the horizontal direction can be dealt with more largely. Therefore, when it is desired to make the horizontal viewing angle of the screen larger than the vertical viewing angle, Especially effective.

Further, although the first light receiving element and the second light receiving element are respectively the light receiving element for detection and the light receiving element for reference, the arrangement of the light receiving element for detection and the light receiving element for reference may be reversed. At this time, the arrangement of the band pass filters can be replaced accordingly.

Also, for example, in the above-described embodiment, the optical component sensor 1 detects moisture as a component contained in the object 2, but the present invention is not limited to this. 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 of alcohol to be detected and reference light not including an absorption wavelength of alcohol.

Further, both the first modification and the second modification may be combined into one embodiment in the above embodiment.

In addition, the present invention can be realized by arbitrarily combining components and functions in each embodiment without departing from the scope of the present invention or embodiments obtained by applying various modifications that those skilled in the art may think to each embodiment. The form is also included in the present invention.

Reference Signs List 1 optical component sensor 2 object 10 housing 20 light emitting optical module 21 light source 22 light emitting lens (light emitting unit)
30 light receiving optical module 31 light receiving lens 32a detection band pass filter (first filter)
32b Bandpass filter for reference (second filter)
33a Light receiving element for detection (first light receiving element)
33b Reference light receiving element (second light receiving element)
34 half mirror 40 control circuit 50 signal processing circuit

Claims

A light source emitting emitted light including an absorption wavelength by a predetermined component;
A housing for accommodating the light source;
A light projecting unit that emits toward a target located outside the housing;
A light receiving lens for collecting light reflected by the object;
A first filter that transmits light of a first wavelength band among the light collected by the light receiving lens and reflects light of a second wavelength band;
A second filter for transmitting the light of the second wavelength band among the light collected by the light receiving lens;
A first light receiving element housed in the housing, receiving the detection light transmitted through the first filter, and converting the detection light into a first electric signal;
An optical component sensor comprising: a second light receiving element which is accommodated in the housing, receives the reference light transmitted through the second filter, and converts the reference light into a second electric signal.
Further equipped with a half mirror,
The light collected by the light receiving lens is incident on the half mirror,
Of the light transmitted through the half mirror, light of the first wavelength band is transmitted through the first filter and received by the first light receiving element,
2. The optical component sensor according to claim 1, wherein the light of the second wavelength band among the light reflected by the half mirror is transmitted through the second filter and received by the second light receiving element.
The optical system according to claim 1 or 2, wherein respective lights transmitted through the first filter and the second filter are condensed by a condenser lens and received by the first light receiving element and the second light receiving element. Component sensor.
The optical component sensor according to any one of claims 1 to 3, wherein the component is moisture.