JP2017161411A - Optical component sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly general-purpose optical component sensor.SOLUTION: An optical component sensor 1 comprises: a detection light source 21 which emits detection light LD1 containing an absorption wavelength by a predetermined component; a reference light source 22 which emits reference light LR1 not containing the absorption wavelength by the component; a housing 10 for housing the detection light source 21 and the reference light source 22; a detection light-receiving element 31 which receives reflection detection light LD4 reflected by an object 2 located outside the housing 10, and is housed in the housing 10; a reference light-receiving element 32 which receives reflection reference light LR4 reflected by the object 2, and is housed in the housing 10; a signal processing circuit 70 which detects a component contained in the object 2 on the basis of a detection signal corresponding to the reflection detection light LD4 output from the detection light-receiving element 31 and a reference signal corresponding to the reflection reference light LR4 output from the reference light-receiving element 32; and a control circuit 60 which individually controls emission of the detection light source 21 and emission of the reference light source 22.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.

  As an analyzer that performs component analysis of a sample, for example, an analyzer described in Patent Document 1 is known. The analyzer described in Patent Document 1 is an apparatus that analyzes a sample based on the optical characteristics of the sample in a reaction tube.

JP 2009-47545 A

  The above-described conventional analyzer has a problem that the sample in the reaction tube can be analyzed, but an object that cannot be put in the reaction tube cannot be analyzed, and the versatility is low.

  Accordingly, an object of the present invention is to provide an optical component sensor with high versatility.

  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. 2 light sources, a housing that houses the first light source and the second light source, and reflected detection light that is at least part of the detection light reflected by an object located outside the housing. A first light receiving element housed in the housing, and a second light receiving element housed in the housing that receives reflected reference light that is at least part of the 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. Detecting signal Comprising a sense circuit, and a control circuit for individually controlling the light emission of the first light source emitting a second light source.

  According to the present invention, an optical component sensor with high versatility can be provided.

2 is a schematic diagram illustrating a configuration of an optical component sensor according to Embodiment 1. FIG. 3 is a block diagram illustrating a functional configuration of the optical component sensor according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating an absorption spectrum of moisture that is a detection target of the optical component sensor according to the first embodiment. It is a figure which shows the spectrum of the detection light of the optical component sensor which concerns on Embodiment 1, and reference light. 6 is a diagram illustrating sensitivity characteristics of a light receiving element of the optical component sensor according to Embodiment 1. FIG. 3 is a time chart illustrating the operation of the optical component sensor according to the first embodiment. 6 is a diagram illustrating an example of an optical path of detection light of the optical component sensor according to Embodiment 1. FIG. 5 is a diagram illustrating an example of an optical path of reference light of the optical component sensor according to Embodiment 1. FIG. 6 is a diagram illustrating an example of an optical path of detection light of the optical component sensor according to Embodiment 1. FIG. 5 is a diagram illustrating an example of an optical path of reference light of the optical component sensor according to Embodiment 1. FIG. 6 is a time chart showing the operation of the optical component sensor according to the second embodiment. It is a schematic diagram which shows the structure of the optical component sensor which concerns on the modification of embodiment. It is a figure which shows the transmission spectrum of the optical filter which concerns on the modification of 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 the modification of embodiment.

  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. Moreover, in each figure, the same code | symbol is attached | subjected about the same structural member.

(Embodiment 1)
[Optical sensor]
First, the outline | summary of the optical component sensor which concerns on Embodiment 1 is demonstrated using FIG.1 and FIG.2. FIG. 1 is a schematic 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.

  The optical component sensor 1 irradiates the object 2 with two lights having different wavelengths (detection light and reference light), and receives reflected light (reflection detection light and reflected reference light) from the object 2. It is a non-contact optical sensor that detects a component contained in the object 2. In this Embodiment, the optical component sensor 1 detects the water | moisture content contained in the target object 2 located in the distant position.

  Although the target object 2 is not specifically limited, For example, it is clothing etc. 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 damage of the clothing by overdrying etc. can be suppressed.

  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, an optical element 40, A detection lens 51 and a reference lens 52 are provided. As shown in FIG. 2, the optical component sensor 1 includes a light separation unit 41, a control circuit 60, and a signal processing circuit 70.

  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 houses a detection light receiving element 31, a reference light receiving element 32, and an optical element 40.

  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 shielding property with respect to the detection light LD1 and the 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, an opening for emitting light emitted from the detection light source 21 and the reference light source 22 to the outside is provided on the outer wall of the housing 10.

[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.

  FIG. 3 is a diagram illustrating an absorption spectrum of moisture that is a detection target of the optical component sensor 1 according to the present embodiment. As shown in FIG. 3, moisture has an absorption peak at a wavelength of about 1450 nm.

  FIG. 4 is a diagram illustrating spectra of detection light and reference light of the optical component sensor 1 according to the present embodiment. As shown in FIG. 4, the detection light LD1 is infrared light including 1450 nm, which is an absorption wavelength due to moisture, as a peak wavelength.

  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.

  As shown in FIG. 1, the detection light source 21 is fixed at a predetermined position in the housing 10. In the present embodiment, the detection light source 21 is disposed so as to face the reference light receiving element 32 with the optical element 40 interposed therebetween. The detection light LD1 emitted from the detection light source 21 is partially reflected (emitted detection light LD3) by the optical element 40 and emitted to the outside of the housing 10, and the other part (partial detection light LD2) is the optical element. The light passes through 40 and enters the reference light receiving element 32. Details will be described later with reference to FIG. 7A.

[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. 4, the reference light LR1 does not include a wavelength of about 1450 nm, which 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.

  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 fixed to a predetermined position in the housing 10 as shown in FIG. In the present embodiment, the reference light source 22 is disposed so as to face the detection light receiving element 31 with the optical element 40 interposed therebetween. The reference light LR1 emitted from the reference light source 22 is partially reflected (emitted reference light LR3) by the optical element 40 and emitted to the outside of the housing 10, and the other part (partial reference light LR2) is the optical element. 40 passes through and enters the light receiving element 31 for detection. Details will be described later with reference to FIG. 7B.

[Light-receiving element for detection]
The detection light receiving element 31 is an example of a first light receiving element that receives the reflected detection light LD4 that is at least a part of the detection light LD1 reflected by the object 2. The detection light receiving element 31 photoelectrically converts the received reflected detection light LD4 to generate a detection signal that is an electrical signal corresponding to the amount of received light (that is, the intensity) of the reflected detection light LD4. The generated detection signal is output to the signal processing circuit 70.

  The reflected detection light LD4 is light obtained by reflecting the emission detection light LD3, which is a part of the detection light LD1, by the object 2. The peak wavelength of the reflected detection light LD4 is the same as the peak wavelength (about 1450 nm) of the detection light LD1.

  In the present embodiment, the detection light receiving element 31 further receives a partial reference light LR2 that is a part of the reference light LR1. Note that the peak wavelength of the partial reference light LR2 is the same as the peak wavelength (about 1300 nm) of the reference light LR1. The detection light receiving element 31 photoelectrically converts the received partial reference light LR2 to generate a partial reference signal that is an electrical signal corresponding to the amount of light received by the partial reference light LR2. The generated partial reference signal is output to the signal processing circuit 70.

  FIG. 5 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. 5 is used for each of the detection light receiving element 31 and the reference light receiving element 32.

  Specifically, as shown in FIG. 5, 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.

  Thus, the detection light receiving element 31 has a sufficiently high light reception sensitivity with respect to the peak wavelengths of the detection light LD1 and the reference light LR1. Therefore, the detection light receiving element 31 can receive the reflection detection light LD4 and the partial reference light LR2, and can generate an electrical signal corresponding to each received light amount.

  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 LR4 that is at least part of the reference light LR1 reflected by the object 2. The reference light receiving element 32 photoelectrically converts the received reflected reference light LR4 to generate a reference signal that is an electrical signal corresponding to the amount of light received by the reflected reference light LR4. The generated reference signal is output to the signal processing circuit 70.

  The reflected reference light LR4 is light obtained by reflecting the outgoing reference light LR3, which is a part of the reference light LR1, by the object 2. The peak wavelength of the reflected reference light LR4 is the same as the peak wavelength (about 1300 nm) of the reference light LR1.

  In the present embodiment, the reference light receiving element 32 further receives a partial detection light LD2 that is a part of the detection light LD1. The peak wavelength of the partial detection light LD2 is the same as the peak wavelength (about 1450 nm) of the detection light LD1. The reference light receiving element 32 photoelectrically converts the received partial detection light LD2 to generate a partial detection signal that is an electrical signal corresponding to the amount of light received by the partial detection light LD2. The generated partial detection signal is output to the signal processing circuit 70.

  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 wavelengths of the detection light LD1 and the reference light LR1. Therefore, the reference light receiving element 32 can receive the reflected reference light LR4 and the partial detection light LD2, and can generate an electrical 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.

[Optical element]
The optical element 40 emits at least a part of the detection light LD1 and at least a part of the reference light LR1 from the housing 10 toward the object 2 in the same spot size. The optical element 40 has, for example, a concave reflection surface, and reflects a part of the detection light LD1 and a part of the reference light LR1 by the reflection surface. A part of the detection light LD1 and a part of the reference light LR1 are reflected at the same light distribution angle in the same direction, for example.

  A part of the detection light LD1 and a part of the reference light LR1 reflected by the optical element 40 are emitted toward the object 2 located outside the housing 10 as the emission detection light LD3 and the emission reference light LR3, respectively. The The emission detection light LD3 and the emission reference light LR3 are irradiated to the same part of the object 2 with the same spot size.

  The optical element 40 has a light separation unit 41 shown in FIG. That is, the optical element 40 has a function of separating the detection light LD1 and the reference light LR1.

  Specifically, the light separation unit 41 separates the detection light LD1 into the emission detection light LD3 and the partial detection light LD2. The emission detection light LD3 is a part of the detection light LD1 and is emitted to the outside of the housing 10. The partial detection light LD2 is a part of the detection light LD1 and is incident on the reference light receiving element 32.

  Further, the light separation unit 41 separates the reference light LR1 into the outgoing reference light LR3 and the partial reference light LR2. The outgoing reference light LR3 is a part of the reference light LR1 and is emitted to the outside of the housing 10. The partial reference light LR <b> 2 is a part of the reference light LR <b> 1 and is incident on the detection light receiving element 31.

  The separation ratio Md of the detection light LD1 and the separation ratio Mr of the reference light LR1 by the light separation unit 41 are designed in advance so as to satisfy a predetermined condition based on the detection resolution DRmin of the detection target component. This condition will be described in detail later.

  The optical element 40 is, for example, a beam splitter (half mirror), but is not limited thereto. The optical element 40 may be, for example, a mirror (concave mirror) provided with a slit. The slit corresponds to the light separation unit 41. The separation ratios Md and Mr can be set to predetermined values by adjusting the opening width (opening diameter) of the slit.

[Detection lens]
The detection lens 51 is a condensing lens for condensing the reflected detection light LD 4 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 LR4 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.

[Control circuit]
The control circuit 60 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 60 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.

  FIG. 6 is a time chart showing the operation of the optical component sensor 1 according to the present embodiment. Specifically, FIGS. 6A and 6C show the light outputs of the detection light source 21 and the reference light source 22, respectively. FIGS. 6B and 6D show the light reception signals of the detection light receiving element 31 and the reference light receiving element 32, respectively.

  In the present embodiment, as shown in FIGS. 6A and 6C, the control circuit 60 causes the detection light source 21 and the reference light source 22 to emit light exclusively in time. That is, the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22 do not overlap.

  Since the reference light LR1 is not emitted during the light emission period Td of the detection light source 21, the detection light receiving element 31 receives the reflected detection light LD4, and the reference light receiving element 32 receives the partial detection light LD2. Since the detection light LD1 is not emitted during the light emission period Tr of the reference light source 22, the reference light receiving element 32 receives the reflected reference light LR4, and the detection light receiving element 31 receives the partial reference light LR2. Therefore, since the reflected detection light LD4, the partial detection light LD2, the reflected reference light LR4, and the partial reference light LR2 are received independently, it is possible to accurately acquire the received light amount of each light.

  More specifically, the control circuit 60 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 60 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 Td of the detection light source 21 and the light emission period Tr of the reference light source 22 can be made to have the same length and not overlap each other.

  The control circuit 60 may be housed in the housing 10 or attached to the outer surface of the housing 10. Alternatively, the control circuit 60 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 60 is composed of, for example, a drive circuit and a microcontroller. The control circuit 60 includes a nonvolatile memory in which a light source control program is stored, a volatile memory which is a temporary storage area for executing the program, an input / output port, a processor for executing the program, and the like.

[Signal processing circuit]
Based on the detection signal corresponding to the reflected detection light LD4 output from the detection light receiving element 31 and the reference signal corresponding to the reflected reference light LR4 output from the reference light receiving element 32, the signal processing circuit 70 A component contained in the object 2 is detected. Specifically, the signal processing circuit 70 detects the amount of moisture 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.

  In the present embodiment, the signal processing circuit 70 corrects the detection signal based on the difference of the partial detection light LD2 with respect to the reference detection light, and corrects the reference signal based on the difference of the partial reference light LR2 with respect to the reference reference light. To do. The signal processing circuit 70 detects a component based on the corrected detection signal and the corrected reference signal.

  The reference detection light is, for example, partial detection light in an initial state. Specifically, the reference detection light is partial detection light when the detection light source 21 is not deteriorated, such as when the optical component sensor 1 is manufactured (or at the time of factory shipment). Therefore, the difference of the partial detection light LD2 with respect to the reference detection light corresponds to a decrease in the light amount due to deterioration of the detection light source 21, that is, a change from the initial state. The reference detection light is not limited to the initial state, and may be a predetermined signal as long as a decrease in the amount of light due to deterioration of the detection light source 21 can be detected.

  The reference reference light is, for example, partial reference light in an initial state. Specifically, the reference reference light is partial reference light when the reference light source 22 is not deteriorated, such as when the optical component sensor 1 is manufactured. Therefore, the difference of the partial reference light LR2 with respect to the standard reference light corresponds to a decrease in light amount due to deterioration of the reference light source 22, that is, a change from the initial state. The reference reference light is not limited to the initial state, and may be a predetermined signal as long as a decrease in the amount of light due to deterioration of the reference light source 22 can be detected.

  The signal processing circuit 70 may be accommodated in the housing 10 or attached to the outer surface of the housing 10. Alternatively, the signal processing circuit 70 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 70 is, for example, a microcontroller. The signal processing circuit 70 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, and a processor that executes the program.

[Light path]
Next, the optical paths of the detection light and the reference light emitted from the optical component sensor 1 according to the present embodiment will be described with reference to FIGS. 7A and 7B.

  FIG. 7A is a diagram illustrating an optical path of the detection light LD1 of the optical component sensor 1 according to the present embodiment. As shown in FIG. 7A, the detection light LD1 emitted from the detection light source 21 is separated into the partial detection light LD2 and the emission detection light LD3 by the optical element 40. Specifically, a part of the detection light LD1 passes through the optical element 40 and enters the reference light receiving element 32 as the partial detection light LD2.

  Another part of the detection light LD1 is reflected by the optical element 40, is emitted to the outside from the housing 10 as outgoing detection light LD3, and travels toward the object 2. The housing 10 is provided with an opening (not shown) for emitting the emission detection light LD3 to the outside.

  The emission detection light LD3 is reflected by the object 2. At this time, when the object 2 contains moisture, a part of the emission detection light LD3 is absorbed by the moisture. As the amount of moisture increases, the amount of absorption increases, so the optical energy of the reflected detection light LD4 becomes lower than that of the emission detection light LD3 depending on the amount of moisture. The reflected detection light LD 4 is collected by the detection lens 51 and enters the detection light receiving element 31.

  In practice, the light energy of the reflected detection light LD4 is attenuated also by factors other than moisture, such as the reflectance of the object 2, but the same applies to the reflected reference light LR4. In the present embodiment, the influence of factors other than moisture can be canceled by calculating the ratio of the optical energy of the reflected detection light LD4 and the reflected reference light LR4.

  FIG. 7B is a diagram illustrating an optical path of the reference light LR1 of the optical component sensor 1 according to the present embodiment. As shown in FIG. 7B, the reference light LR1 emitted from the reference light source 22 is separated into the partial reference light LR2 and the outgoing reference light LR3 by the optical element 40. Specifically, a part of the reference light LR1 passes through the optical element 40 and enters the detection light receiving element 31 as the partial reference light LR2.

  Another part of the reference light LR1 is reflected by the optical element 40, is emitted to the outside from the housing 10 as outgoing reference light LR3, and travels toward the object 2. The outgoing reference light LR3 passes through, for example, an opening through which the outgoing detection light LD3 passes.

  The outgoing reference light LR3 is reflected by the object 2. Note that the emission reference light LR3 and the emission detection light LD3 are emitted from the housing 10 in the same spot size. For this reason, the outgoing reference light LR3 is applied to the same part as the part of the target 2 irradiated with the outgoing detection light LD3.

  Since the outgoing reference light LR3 does not include a wavelength that is absorbed by moisture, it is reflected almost without being absorbed regardless of whether or not the object 2 includes moisture. Therefore, the optical energy of the reflected reference light LR4 becomes the same as the optical energy of the outgoing reference light LR3 (in practice, the optical energy of the reflected reference light LR4 is attenuated by the reflectance of the object 2). . The reflected reference light LR4 is collected by the reference lens 52 and enters the reference light receiving element 32.

  In the example shown in FIG. 7A, only the representative optical path of the light diffusely reflected by the object 2 from the emission detection light LD3 is shown as the reflection detection light LD4, but the reflection detection light is also transmitted to the reference lens 52. Incident. For example, in FIG. 7C described later, another reflection component is shown as the reflection detection light LD5.

  For this reason, for example, a mechanically movable shielding member (not shown) is provided on the incident surface side or the emission surface side of the reference lens 52 so that the reflection detection light LD4 is not received by the reference light receiving element 32. It has been. Alternatively, an optical filter shown in a later-described modification may be provided on the incident surface side or the emission surface side of the reference lens 52. Similarly, for example, mechanically movable on the incident surface side or the emission surface side of the detection lens 51 so that the reflected reference light (see the reflected reference light LR5 in FIG. 7D) is not received by the detection light receiving element 31. A shielding member or an optical filter may be provided.

  As shown in FIG. 6, in the light emission period Td in which the detection light LD1 is emitted, the detection light receiving element 31 receives the reflection detection light LD4, so that a detection signal corresponding to the reflection detection light LD4 is sent to the signal processing circuit 70. Output to. In the light emission period Td, the reference light receiving element 32 receives the partial detection light LD2, and outputs a partial detection signal corresponding to the partial detection light LD2 to the signal processing circuit 70.

  Since the partial detection light LD2 is a predetermined proportion of the detection light LD1, when the output of the detection light LD1 decreases due to deterioration of the detection light source 21, a signal of a partial detection signal corresponding to the partial detection light LD2 Level Vmd decreases. Therefore, by acquiring the light energy of the partial detection light LD2 and calculating the change from the initial state, for example, it is possible to acquire the degree of deterioration of the detection light source 21 (change in light energy).

  Similarly, in the light emission period Tr in which the reference light LR1 is emitted, the reference light receiving element 32 receives the reflected reference light LR4 and outputs a reference signal corresponding to the reflected reference light LR4 to the signal processing circuit 70. In the light emission period Tr, the detection light receiving element 31 receives the partial reference light LR2, and outputs a partial reference signal corresponding to the partial reference light LR2 to the signal processing circuit 70.

  Since the partial reference light LR2 is a predetermined proportion of the reference light LR1, the signal of the partial reference signal corresponding to the partial reference light LR2 when the output of the reference light LR1 drops due to deterioration of the reference light source 22 Level Vmr decreases. Therefore, by acquiring the light energy of the partial reference light LR2, and calculating the change from the initial state, for example, the degree of deterioration of the reference light source 22 (change in light energy) can be acquired.

[Signal processing (detection processing)]
Next, signal processing (component detection processing) by the signal processing circuit 70 will be described.

  In the present embodiment, the signal processing circuit 70 compares the light energy Pd of the reflected detection light LD4 and the light energy Pr of the reflected reference light LR4, thereby detecting the amount of components included in the target object 2.

  The optical energy Pd of the reflected detection light LD4 incident on the detection light receiving element 31 is expressed by the following (Equation 1).

(Formula 1) Pd = Pd0 × Gd × Rd × 10 ^{−A × C × D}

  Here, Pd0 is the light energy of the detection light LD1 emitted by the detection light source 21. Gd is the coupling efficiency (condensation rate) of the detection light emitted from the detection light source 21 to the detection light receiving element 31. Specifically, Gd is a ratio of a part of the detection light LD1 that is separated by the light separation unit 41 and becomes a part of the component diffusely reflected by the object 2 (that is, the reflected detection light LD4). Equivalent to.

  Rd is the reflectance of the emission detection light LD3 by the object 2. A is the absorbance of the outgoing detection light LD3 due to the component (water). C is the volume concentration of the component 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 detection light.

  More specifically, in an object in which moisture is uniformly dispersed, C is included in the component of the object 2 when light is incident on the object 2, reflected inside and emitted from the object 2. Corresponds to 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, since A × C × D corresponds to the amount of component (water content) included in the object 2, the amount of component can be calculated based on (Equation 1).

  Similarly, the optical energy Pr of the reflected reference light LR4 incident on the reference light receiving element 32 is expressed by the following (Expression 2).

  (Formula 2) Pr = Pr0 × Gr × Rr

  Here, Pr0 is the light energy of the reference light LR1 emitted from the reference light source 22. Gr is the coupling efficiency (condensation rate) of the reference light emitted from the reference light source 22 to the reference light receiving element 32. Specifically, Gr is a ratio of a part of the reference light LR1 that is separated by the light separation unit 41 and becomes a part of the component diffusely reflected by the object 2 (that is, the reflected reference light LR4). Equivalent to. Rr is the reflectance of the outgoing reference light LR3 by the object 2.

  In the present embodiment, the outgoing detection light LD3 and the outgoing reference light LR3 are irradiated coaxially and at the same spot size, so that the detection light coupling efficiency Gd and the reference light coupling efficiency Gr are substantially equal. In the present embodiment, since the emission detection light LD3 and the emission reference light LR3 have relatively close peak wavelengths, the reflectance Rd of the emission detection light LD3 and the reflectance Rr of the reference light LR3 are substantially equal. .

  Therefore, the following (Expression 3) is derived from (Expression 1) and (Expression 2).

(Formula 3) Pd / Pr = (Pd0 / Pr0) × 10 ^{−A × C × D}

  The signal processing circuit 70 calculates the light energy Pd of the reflected detection light LD4 based on the detection signal, and calculates the light energy Pr of the reflected reference light LR4 based on the reference signal. Specifically, the signal level Vd of the detection signal shown in FIG. 6B corresponds to the light energy Pd, and the signal level Vr of the reference signal shown in FIG. 6D corresponds to the light energy Pr.

  Further, the signal processing circuit 70 obtains the light energy Pd0 of the detection light LD1 and the light energy Pr0 of the reference light LR1 based on the output of the emitted light of each of the detection light source 21 and the reference light source 22. The light energies Pd0 and Pr0 are predetermined as initial outputs of the detection light source 21 and the reference light source 22, for example.

  Therefore, the signal processing circuit 70 can calculate A × C × D corresponding to the component amount (water content) of the object 2 based on (Equation 3).

  Note that the detection light source 21 and the reference light source 22 decrease the light energy of the emitted light due to deterioration over time. For example, when the light energy of the detection light LD1 is lowered, the light energy Pd of the reflected detection light LD4 is lowered, so that the component detection result cannot be obtained correctly.

  On the other hand, in the present embodiment, the signal processing circuit 70 corrects the detection signal based on the difference of the partial detection light LD2 with respect to the reference detection light, and based on the difference of the partial reference light LR2 with respect to the reference reference light. Correct the reference signal. That is, the above (Formula 3) is replaced by the following (Formula 4) using the corrected light energies Pd ′ and Pr ′.

(Formula 4) Pd ′ / Pr ′ = (Pd0 / Pr0) × 10 ^{−A × C × D}

  Specifically, the signal processing circuit 70 calculates a correction coefficient based on the difference of the partial detection light LD2 with respect to the reference detection light, and corrects the light energy Pd by multiplying the detection signal. The correction coefficient is expressed by, for example, the following (Formula 5).

  (Formula 5) Correction coefficient = Pmd0 / Pmd

  Pmd0 is the light energy of the partial detection light LD2 in the initial state. Pmd0 is a value obtained by multiplying the light energy Pd0 determined in advance as the initial output of the light source 21 for detection by the separation ratio Md. Pmd is the light energy of the partial detection light LD2 received by the reference light receiving element 32. Specifically, the signal level Vmd of the output signal (partial detection signal) of the reference light receiving element 32 shown in FIG. 6D corresponds to the light energy Pmd.

  Thereby, the corrected light energy Pd ′ is expressed by the following (formula 6).

  (Formula 6) Pd ′ = Pd × Pmd0 / Pmd

  Similarly, the signal processing circuit 70 calculates a correction coefficient based on the difference of the partial reference light LR2 with respect to the reference reference light, and corrects the light energy Pr by multiplying the reference signal. The correction coefficient is expressed by, for example, the following (Expression 7).

  (Expression 7) Correction coefficient = Pmr0 / Pmr

  Pmr0 is the light energy of the partial reference light LR2 in the initial state. Pmr0 is a value obtained by multiplying a predetermined optical energy Pr0 as an initial output of the reference light source 22 by the separation ratio Mr. Pmr is the light energy of the partial reference light LR2 received by the detection light receiving element 31. Specifically, the signal level Vmr of the output signal (partial reference signal) of the detection light receiving element 31 shown in FIG. 6B corresponds to the light energy Pmr.

  As a result, the corrected light energy Pr ′ is expressed by the following (Equation 8).

  (Formula 8) Pr ′ = Pr × Pmr0 / Pmr

  Therefore, the signal processing circuit 70 performs (Expression 4), (Expression 6), and (Expression 8), the light energy Pd of the reflected detection light LD4, the light energy Pmr of the partial reference light LR2, and the light energy of the reflected reference light LR4. Based on Pr and the light energy Pmd of the partial detection light LD2, A × C × D corresponding to the component amount of the object 2 can be calculated.

[Separation conditions]
As described above, in the example shown in FIG. 7A, only the optical path where the reflected detection light LD4 enters the detection lens 51 is shown, but the reflected detection light also enters the reference lens 52. For this reason, for example, a mechanically movable shielding member (not shown) or the like is provided on the incident surface side or the emission surface side of the reference lens 52 so that the reflection detection light is not received by the reference light receiving element 32. ing. Alternatively, an optical filter shown in a later-described modification may be provided on the incident surface side or the emission surface side of the reference lens 52. Similarly, for example, a mechanically movable shielding member or optical filter may be provided on the incident surface side or the emission surface side of the detection lens 51 so that the reflected reference light is not received by the detection light receiving element 31. Good. In this case, various parts are added and the cost is increased, but correction of light source deterioration by the monitor is easy.

  On the other hand, as shown in FIG. 7C, not only the reflected detection light LD4 incident on the detection lens 51 but also the reflected detection light LD5 incident on the reference lens 52 in a different direction exists. A method of correcting light source deterioration in the case where the reflection detection light LD5 is incident on the reference light receiving element 32 without adding the above-described various components will be described below.

  In the present embodiment, the component detection resolution DR is expressed by (Equation 9).

(Formula 9) DR = 1-10 ^{−A × C × D}

At this time, the minimum detection resolution DRmin necessary for detecting the component is the minimum value to be detected, which is 1-10 ^{−A × C × D} , and the object related to the absorbance A, concentration C, and contribution thickness D of the component. 2 is determined.

  Here, the optical energy PD2 of the partial detection light LD2 that is separated from the detection light LD1 by the light separation unit 41 and incident on the reference light receiving element 32 is expressed by (Equation 10) using the separation ratio Md of the detection light LD1. Is done.

  (Formula 10) PD2 = PD0 × Md

  The light energy PDr incident on the reference light receiving element 32 by the reflected detection light LD5 incident on the reference lens 52 is expressed by (Equation 11).

(Formula 11) PDr = PD0 * Gdr * Rd * 10- ^{A * C * D}

  Gdr is the coupling efficiency (condensing rate) of the detection light emitted from the detection light source 21 to the reference light receiving element 32. Specifically, Gdr is a ratio of the part of the detection light LD1 that is separated by the light separation unit 41 and becomes a part of the component diffusely reflected by the object 2 (that is, the reflected detection light LD5). Equivalent to. That is, Gdr is the coupling efficiency for detection with respect to the detection light LD1 of light energy incident on the reference light receiving element 32 as the reflection detection light LD5 as shown in FIG. 7C.

  Here, assuming that PDrmax where PDr without absorption attenuation due to the component included in the object 2 is maximum is PDrmax, (Expression 11) becomes (Expression 12).

  (Formula 12) PDrmax = PD0 × Gdr × Rd

  For these reasons, the sum of the light energy finally incident on the reference light receiving element 32 with respect to the detection light LD1 is PD2 + PDr.

  Here, since the lower limit value of the light energy incident on the reference light receiving element 32 requires the necessary detection resolution DRmin of the component for the detection light receiving element 31, the light energy incident on the reference light receiving element 32 of the same type is required. The maximum value of the sum is expressed by (Equation 13).

  (Formula 13) PD2 + PDrmax> PD0 × Gd × Rd × DRmin

  (Expression 14) is derived by expanding (Expression 13) using (Expression 10) and (Expression 11).

  (Formula 14) Md> Rd × (Gd × DRmin−Gdr)

  On the other hand, in order not to deteriorate the necessary detection resolution DRmin of the component, it is necessary to maximize the light energy of the outgoing detection light LD3, and it is necessary to reduce the separation ratio Md of the partial detection light LD2 as much as possible. The relational expression for this is expressed by (Expression 15).

  (Expression 15) PD0 × Gd × Rd × DRmin> PD0 × Md

  Therefore, the separation ratio Md of the detection light LD1 satisfies the relationship of (Equation 16).

  (Expression 16) Gd × Rd × DRmin> Md> Rd × (Gd × DRmin−Gdr)

  Further, since the component amount of the reference light LR1 is estimated using the ratio between the detection light reception signal and the reference light reception signal, the same relationship is required for the separation ratio Mr of the reference light LR1. Specifically, the separation ratio Mr of the reference light LR1 satisfies the relationship of (Equation 17).

  (Formula 17) Gr × Rr × DRmin> Mr> Rr × (Gr × DRmin−Grd)

  Here, Grd is the coupling efficiency (condensing rate) of the reference light emitted from the reference light source 22 to the light receiving element 31 for detection. Specifically, Grd is a ratio of a part of the reference light LR1 that is separated by the light separation unit 41 and becomes a part of the component diffusely reflected by the object 2 (that is, the reflected reference light LR5). Equivalent to. That is, as shown in FIG. 7D, Grd is the detection coupling efficiency with respect to the reference light LR1 of the light energy incident on the detection light receiving element 31 as the reflected reference light LR5.

  From the above, the light separation unit 41 according to the present embodiment separates the detection light LD1 and the reference light LR1 under the conditions satisfying (Expression 16) and (Expression 17).

  Thereby, there is no need to provide a mechanically movable shielding member, an optical filter, etc. separately, and weight reduction, size reduction, and cost reduction can be achieved.

[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. Reflection detection which is at least a part of the detection light LD1 reflected by the object light source 22, the casing 10 housing the detection light source 21 and the reference light source 22, and the object 2 located outside the casing 10 The detection light receiving element 31 received in the housing 10 that receives the light LD4 and the reflected reference light LR4 that is at least part of the reference light LR1 reflected by the object 2 are received in the housing 10. The received reference light receiving element 32, the detection signal corresponding to the reflected detection light LD4 output from the detection light receiving element 31, and the reference signal corresponding to the reflected reference light LR4 output from the reference light receiving element 32. Based on the bets, it includes a signal processing circuit 70 for detecting a component object 2 comprises, a control circuit 60 for individually controlling the light emission of the light emitting and the reference light source 22 of the detection light source 21.

  Thereby, since the optical component sensor 1 detects the component which the target object 2 located in the exterior of the housing | casing 10 contains, it is applicable to various use environments. Thus, according to this Embodiment, the optical component sensor 1 with high versatility can be provided.

  Further, for example, the optical component sensor 1 further includes at least a part of the detection light LD1 (emitted detection light LD3) and at least a part of the reference light LR1 (emission reference light LR3) coaxially and with the same spot size. The optical element 40 which radiate | emits toward the target object 2 from 10 is provided.

  As described above, since the emission detection light LD3 and the emission reference light LR3 having different wavelengths are irradiated on the object 2 with the same spot size, the optical component sensor 1 has the shape or size of the object 2 or the like. The components included in the object 2 can be detected without being restricted. Thereby, the versatility of the optical component sensor 1 can be further improved. For example, the object 2 may be separated from the housing 10, and the optical component sensor 1 is used as a non-contact type moisture amount sensor.

  Further, for example, the detection light receiving element 31 further receives a partial reference light LR2 that is a part of the reference light LR1, and the reference light receiving element 32 further includes a partial detection light LD2 that is a part of the detection light LD1. The signal processing circuit 70 corrects the detection signal based on the difference of the partial detection light LD2 with respect to the standard detection light, and corrects the reference signal based on the difference of the partial reference light LR2 with respect to the standard reference light, A component is detected based on the corrected detection signal and the corrected reference signal.

  The difference between the partial detection light LD2 and the reference detection light corresponds to the amount of decrease in the light energy of the partial detection light LD2, and corresponds to the amount of deterioration of the detection light source 21. Therefore, the optical component sensor 1 according to the present embodiment can correct the detection signal in accordance with the deterioration amount of the detection light source 21. Similarly, the optical component sensor 1 can correct the reference signal according to the deterioration amount of the reference light source 22. Thereby, since the optical component sensor 1 detects a component based on the detection signal and the reference signal in which the decrease in the amount of light due to deterioration is corrected, the component detection accuracy can be increased.

  Further, since the reference light receiving element 32 is used for receiving the partial detection light LD2 and the detection light receiving element 31 is used for receiving the partial reference light LR2, a new light receiving light for the partial detection light LD2 or the partial reference light LR2 is used. A light receiving element is not required separately. Therefore, since the number of parts can be reduced, the optical component sensor 1 can be reduced in size and cost.

  For example, the control circuit 60 causes the detection light source 21 and the reference light source 22 to emit light exclusively in time.

  Thus, when the reflected detection light LD4 is received by the detection light receiving element 31, the partial reference light LR2 is not received. Therefore, it is not necessary to separate the detection signal and the partial reference signal from the output signal. The amount of processing can be reduced. The same applies to the case of the reference light receiving element 32. Therefore, the amount of processing can be reduced, and the power consumption for signal processing can be reduced. Moreover, since electric current is intermittently supplied to the light source 21 for detection and the light source 22 for reference, power consumption can be reduced.

  Further, for example, the optical component sensor 1 further detects the detection light LD 1 emitted from the detection light source 21, the emission detection light LD 3 emitted to the outside of the housing 10, and the partial detection light incident on the reference light receiving element 32. The reference light LR1 separated from the LD 2 and emitted from the reference light source 22 is separated into the outgoing reference light LR3 emitted to the outside of the housing 10 and the partial reference light LR2 incident on the detection light receiving element 31. The light separation unit 41 is provided, the reflection detection light LD4 is light obtained by reflecting the emission detection light LD3 by the object 2, and the reflection reference light LR4 is light obtained by reflecting the emission reference light LR3 by the object 2. .

  In addition, for example, the light separation unit 41 determines that (i) the coupling efficiency of the detection light LD1 to the detection light receiving element 31 is Gd, and the coupling efficiency of the detection light LD1 to the reference light reception element 32 is Gdr. When the reflectance of the emitted detection light LD3 is Rd and the minimum detection resolution for detecting the component is DRmin, the separation ratio Md indicating the partial detection light LD2 with respect to the detection light LD1 is Gd × Rd × DRmin> Md> Rd ×. The detection light LD1 emitted by the detection light source 21 is separated into the emission detection light LD3 and the partial detection light LD2 under the condition satisfying (Gd × DRmin−Gdr), and (ii) the reference light LR1 is coupled to the reference light receiving element 32. When the efficiency is Gr and the coupling efficiency of the reference light LR1 to the detection light receiving element 31 is Grd, the reflectance of the outgoing reference light LR3 by the object 2 is Rr. The reference light LR1 emitted from the reference light source 22 is output under the condition that the separation ratio Mr indicating the partial reference light LR2 with respect to the reference light LR1 satisfies Gr × Rr × DRmin> Mr> Rr × (Gr × DRmin−Grd). The light LR3 and the partial reference light LR2 are separated.

  Thereby, it is possible to correct the deterioration of the light source by receiving the partial detection light LD2 and the partial reference light LR2 without impairing the detection accuracy of the component amount.

  In addition, for example, the detection light source 21 and the reference light source 22 are distributed light sources that emit light having different wavelengths, so that the light intensity for each wavelength is higher than when a non-dispersion light source such as a halogen lamp is provided. No change detection is required. Therefore, since the number of parts can be reduced, the optical component sensor 1 can be reduced in size and cost.

(Embodiment 2)
Next, the optical component sensor according to Embodiment 2 will be described.

  The optical component sensor 1 according to the present embodiment has the same configuration as the optical component sensor 1 according to the first embodiment, and the control method of the two light sources by the control circuit 60 and the signal processing The signal processing method by the circuit 70 is different. Hereinafter, the description of the same configuration and operation as those of the first embodiment will be omitted or simplified.

  In the present embodiment, the control circuit 60 partially overlaps the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22 based on the signal level of the detection signal. Specifically, when the signal level of the detection signal is smaller than the predetermined threshold value Vth, the control circuit 60 partially overlaps the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22. Thus, the light source 21 for detection and the light source 22 for reference are made to light-emit alternately. When the signal level of the detection signal is greater than the predetermined threshold value Vth, the control circuit 60 causes the detection light source 21 and the reference light source 22 to repeatedly emit light alternately and exclusively in time. As described above, the control circuit 60 switches between the overlap mode and the time exclusive mode based on the signal level of the detection signal.

  The time exclusive mode is the operation described in FIG. 6 in the first embodiment.

  Note that, as described above, in the example illustrated in FIG. 7A, only the optical path through which the reflected detection light LD4 enters the detection lens 51 is illustrated, but the reflected detection light LD4 also enters the reference lens 52. For this reason, for example, a mechanically movable shielding member (not shown) is provided on the incident surface side or the emission surface side of the reference lens 52 so that the reflection detection light LD4 is not received by the reference light receiving element 32. It has been. Alternatively, an optical filter shown in a later-described modification may be provided on the incident surface side or the emission surface side of the reference lens 52. Similarly, for example, a mechanically movable shielding member or an optical filter is provided on the incident surface side or the emission surface side of the detection lens 51 so that the reflected reference light LR4 is not received by the detection light receiving element 31. Also good.

  FIG. 8 is a time chart showing the operation of the optical component sensor 1 according to the present embodiment. Specifically, FIG. 8 shows the operation of the control circuit 60 when the signal level of the detection signal is smaller than the threshold value Vth (that is, the overlap mode).

  As shown in FIG. 8B, an overlap period To of the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22 is provided. The overlap period To is provided both after the start of the light emission period Td of the light source 21 for detection and before the end, but either one may be provided. The overlap period To is, for example, 10% to 20% of the light emission period Td (or the light emission period Tr), but is not particularly limited.

  In the period Tdo in which only the detection light source 21 emits light, the detection light receiving element 31 receives only the reflected detection light LD4. That is, the output signal of the detection light receiving element 31 in the period Tdo is a detection signal corresponding to the reflected detection light LD4.

  In the present embodiment, as shown in FIG. 8B, the signal level Vd of the detection signal is lower than the threshold value Vth. The control circuit 60 executes the overlap mode when the signal level Vd is smaller than the threshold value Vth, and provides the overlap period To by overlapping the light emission period Td and the light emission period Tr.

  Specifically, the threshold value Vth is a value based on the power supply voltage of the signal processing circuit 70. For example, the threshold value Vth can be 20% of the power supply voltage of the signal processing circuit 70. For example, when the power supply voltage of the signal processing circuit 70 is 3.3 V, the threshold value Vth is 0.66 V (= 3.3 V × 20%).

  In the overlap period To, the detection light receiving element 31 receives not only the reflected detection light LD4 but also the partial reference light LR2. For this reason, the output signal of the detection light receiving element 31 is a composite signal of the detection signal and the partial reference signal.

  In the overlap mode, the signal processing circuit 70 generates, as a detection signal, a difference between the output signal of the detection light receiving element 31 in the overlap period To and the output signal in the period Tro in which only the reference light source 22 emits light. . Specifically, the signal processing circuit 70 subtracts the signal level Vmr of the output signal (partial reference signal) in the period Tro from the signal level Vmr + Vd of the output signal in the overlap period To, thereby detecting the signal level Vd of the detection signal. Can be calculated. As shown in FIG. 8B, since the detection light receiving element 31 receives only the partial reference light LR2 during the period Tro, the output signal of the detection light receiving element 31 is a partial reference signal.

  As described above, in the optical component sensor 1 according to the present embodiment, for example, the detection light receiving element 31 further receives the partial reference light LR2 that is a part of the reference light LR1, and the control circuit 60 Based on the signal level of the detection signal, the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22 are partially overlapped.

  Thereby, in the overlap period To, the output signal from the detection light receiving element 31 is a signal that is a combination of the detection signal and the partial reference signal, so that the influence of the noise signal can be suppressed. That is, the SN ratio of the output signal of the detection light receiving element 31 can be improved. Therefore, the component can be detected even when the amount of water contained in the object 2 is large and only a weak detection signal can be obtained. Thus, according to the present embodiment, the component detection accuracy can be increased. At this time, it is not necessary to use an element for detecting a weak signal or an expensive element such as a highly sensitive light receiving element, so that the optical component sensor 1 can be reduced in size or cost. .

  For example, the control circuit 60 partially overlaps the light emission period Td of the detection light source 21 and the light emission period Tr of the reference light source 22 when the signal level Vd of the detection signal is smaller than a predetermined threshold Vth. As described above, when the light source 21 for detection and the light source 22 for reference are alternately and repeatedly emitted, and the signal level Vd of the detection signal is greater than the threshold value Vth, the light source 21 for detection and the light source 22 for reference alternate alternately in time. Make it emit light repeatedly.

  Thereby, since it can switch between overlap mode and time exclusion mode, the detection accuracy of a component can be raised and power consumption can be reduced.

  Further, for example, when the signal level Vd of the detection signal is smaller than the predetermined threshold value Vth, the signal processing circuit 70 emits only the output signal of the detection light receiving element 31 in the overlap period To and the reference light source 22. A difference from the output signal of the detection light receiving element 31 during the period Tro is generated as a detection signal.

  Thereby, since a detection signal can be generated from the output signal of the light receiving element 31 for detection in the overlap period To, the component can be detected while suppressing the influence of the noise signal.

(Modification)
Below, the modification of the optical component sensor which concerns on embodiment mentioned above is demonstrated using drawing.

  FIG. 9 is a schematic diagram showing the configuration of the optical component sensor 100 according to this modification. As shown in FIG. 9, the optical component sensor 100 newly includes a detection filter 81 and a reference filter 82 compared to the optical component sensor 1 according to the first embodiment.

  FIG. 10 is a diagram illustrating a transmission spectrum of the optical filter according to the present modification. FIG. 11 is a diagram illustrating an example of an optical path of the detection light LD1 of the optical component sensor 100 according to the present modification.

  The detection filter 81 is an example of a first optical filter that is disposed on the optical path of the reflected detection light LD4 incident on the detection light receiving element 31, transmits the reflected detection light LD4, and absorbs the reflected reference light LR5. . As shown in FIG. 10, the detection filter 81 transmits light having a peak wavelength of 1450 nm of the reflected detection light LD4 and absorbs light having a peak wavelength of 1300 nm of the reflected reference light LR5. Note that the detection filter 81 may transmit a part of 1300 nm light. That is, the detection filter 81 may transmit the reflected reference light LR5 with a transmission amount smaller than the transmission amount of the reflected detection light LD4.

  The reference filter 82 is an example of a second optical filter that is disposed on the optical path of the reflected reference light LR4 incident on the reference light receiving element 32, transmits the reflected reference light LR4, and absorbs the reflected detection light LD5. . As shown in FIG. 10, the reference filter 82 transmits light having a peak wavelength of 1300 nm of the reflected reference light LR4 and absorbs light having a peak wavelength of 1450 nm of the reflected detection light LD5. For this reason, as shown in FIG. 11, the reflection detection light LD5 is absorbed by the reference filter 82 and is not incident on the reference light receiving element 32.

  Note that the reference filter 82 may transmit a part of light of 1450 nm. That is, the reference filter 82 may transmit the reflected detection light LD5 with a transmission amount smaller than the transmission amount of the reflected reference light LR4.

  In this modification, the detection filter 81 and the reference filter 82 are provided, so that the energy of light incident on each of the detection light receiving element 31 and the reference light receiving element 32 is different from that in the first embodiment. Specifically, it is as follows.

  The optical energy Pd of the reflected detection light LD4 incident on the detection light receiving element 31 is expressed by the following (Equation 18).

(Formula 18) Pd = Pd0 × Gd × Rd × Tdd × 10 ^{−A × C × D}

  Here, Tdd is the transmittance of the reflected detection light LD4 by the detection filter 81. Similarly, the optical energy Pdr of the reflected detection light LD5 incident on the reference light receiving element 32 is expressed by the following (Equation 19).

(Formula 19) Pdr = Pd0 * Gr * Rd * Tdr * 10- ^{A * C * D}

  Here, Tdr is the transmittance of the reflected detection light LD5 by the reference filter 82.

  During the period in which the detection light LD1 is emitted, the partial detection light LD2 is also incident on the reference light receiving element 32 at the same time. Therefore, the total energy P of the light received by the reference light receiving element 32 is expressed by the following (formula 20). It is represented by

(Formula 20) P = Pmd + Pdr
= Pd0 * (Md + Gr * Rd * Tdr * 10- ^{A * C * D} )

  Therefore, when the transmittance Tdr of the reference filter 82 is sufficiently small, the term including Tdr on the right side of (Equation 20) can be regarded as zero. As a result, the output signal from the reference light receiving element 32 can be processed as in the first embodiment.

  Here, the reflection detection lights LD4 and LD5 have been described, but the same applies to the reflection reference lights LR4 and LR5. During the period in which the reference light LR1 is emitted, the partial reference light LR2 and the reflected reference light LR4 are incident on the detection light receiving element 31, so that the total energy P of the light received by the detection light receiving element 31 is (Expression 21).

  (Formula 21) P = Pr0 × (Mr + Gd × Rr × Trr)

  Note that Trr is the transmittance of the reflected reference light LR5 by the detection filter 81.

  As described above, in the optical component sensor 100 according to this modification, the optical component sensor 100 is further disposed on the optical path of the reflected detection light LD4 incident on the detection light receiving element 31, transmits the reflected detection light LD4, and reflects. A detection filter 81 that absorbs the light LR5 and a reference filter that is disposed on the optical path of the reflected reference light LR4 incident on the reference light receiving element 32, transmits the reflected reference light LR4, and absorbs the reflected detection light LD5. 82.

  Thereby, it is not necessary to provide a mechanical shielding member, and the optical component sensor 100 can be downsized.

(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-described embodiment, the optical component sensor 1 detects moisture as a component included in the object, but is not limited thereto. For example, the optical component sensor 1 may detect alcohol or oil. For example, the optical component sensor 1 should just irradiate a target object with the detection light containing the absorption wavelength by the alcohol used as detection object, and the reference light which does not contain the absorption wavelength by alcohol. Moreover, the optical component sensor 1 may detect not only a liquid component but gas components, such as a carbon dioxide, for example.

  For example, a member different from the optical element 40 may separate each of the detection light LD1 and the reference light LR1. That is, the light separation unit 41 may be configured by a member different from the optical element 40.

  Further, for example, in the above-described embodiment, the example in which the emission detection light LD3 and the emission reference light LR3 are emitted from the housing 10 with the same spot size is shown, but the present invention is not limited thereto.

  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.

1, 100 Optical component sensor 2 Object 10 Case 21 Light source for detection (first 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 optical element 41 light separation unit 60 control circuit 70 signal processing circuit 81 detection filter 82 reference filter LD1 detection light LD2 partial detection light LD3 emission detection light LD4, LD5 reflection detection light LR1 reference light LR2 partial reference light LR3 emission reference light LR4, LR5 Reflected reference light

Claims (10)

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;
A first light receiving element housed in the housing for receiving reflected detection light that is at least a part of the detection light reflected by an object located outside the housing;
A second light receiving element housed in the housing for receiving reflected reference light that is at least part of the reference light reflected by the object;
The component included in the object is 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. A signal processing circuit to detect;
An optical component sensor comprising: a control circuit that individually controls light emission of the first light source and light emission of the second light source. further,
The optical component sensor according to claim 1, further comprising: an optical element that emits at least a part of the detection light and at least a part of the reference light from the housing toward the target with the same spot size. The first light receiving element further receives a partial reference light that is a part of the reference light,
The second light receiving element further receives partial detection light that is part of the detection light,
The signal processing circuit corrects the detection signal based on a difference of the partial detection light with respect to a reference detection light, and corrects the reference signal based on a difference of the partial reference light with respect to a reference reference light, and after correction The optical component sensor according to claim 1, wherein the component is detected based on the detection signal and the corrected reference signal. The optical component sensor according to claim 3, wherein the control circuit causes the first light source and the second light source to emit light exclusively in time. further,
The detection light emitted from the first light source is separated into outgoing detection light emitted outside the housing and partial detection light incident on the second light receiving element, and reference light emitted from the second light source. A light separating unit for separating the output reference light emitted to the outside of the housing and the partial reference light incident on the first light receiving element,
The reflected detection light is at least a part of the light reflected by the object from the emission detection light,
5. The optical component sensor according to claim 3, wherein the reflected reference light is at least a part of light that is reflected from the object by the outgoing reference light. The light separation unit is
(I) When the coupling efficiency of the detection light emitted from the first light source to the first light receiving element is Gd, and the coupling efficiency of the detection light emitted from the first light source to the second light receiving element is Gdr, When the reflectance of the emitted detection light is Rd and the minimum detection resolution for detecting the component is DRmin, the separation ratio Md indicating the partial detection light with respect to the detection light emitted by the first light source is
(Formula A) Gd × Rd × DRmin>Md> Rd × (Gd × DRmin−Gdr)
Separating the detection light emitted by the first light source into the emission detection light and the partial detection light under the conditions satisfying
(Ii) When the coupling efficiency of the reference light emitted from the second light source to the second light receiving element is Gr, and the coupling efficiency of the reference light emitted from the second light source to the first light receiving element is Grd, When the reflectance of the emitted reference light is Rr, a separation ratio Mr indicating the partial reference light with respect to the reference light emitted by the second light source is
(Formula B) Gr × Rr × DRmin>Mr> Rr × (Gr × DRmin−Grd)
The optical component sensor according to claim 5, wherein the reference light emitted by the second light source is separated into the outgoing reference light and the partial reference light under a condition that satisfies the following conditions. The first light receiving element further receives a partial reference light that is a part of the reference light,
The optical component sensor according to claim 1, wherein the control circuit partially overlaps a light emission period of the first light source and a light emission period of the second light source based on a signal level of the detection signal. . The control circuit includes:
When the signal level of the detection signal is smaller than a predetermined threshold value, the first light source and the second light source are arranged such that the light emission period of the first light source partially overlaps the light emission period of the second light source. Alternately and repeatedly,
The optical component sensor according to claim 7, wherein when the signal level of the detection signal is higher than the threshold value, the first light source and the second light source repeatedly emit light alternately and exclusively in time. When the signal level of the detection signal is lower than a predetermined threshold, the signal processing circuit outputs the output signal of the first light receiving element during the overlap period and the first period during the period when only the second light source emits light. The optical component sensor according to claim 8, wherein a difference from an output signal of a light receiving element is generated as the detection signal. further,
A first optical filter that is disposed on an optical path of the reflected detection light incident on the first light receiving element, transmits the reflected detection light, and absorbs the reflected reference light;
The second optical filter that is disposed on an optical path of the reflected reference light incident on the second light receiving element, transmits the reflected reference light, and absorbs the reflected detection light. The optical component sensor according to claim 1.

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