Grain component sensor and grain component analyzer

Abstract

To provide a grain component sensor and a grain component analyzer which have small sizes, and can reduce maintenance fee and running cost.SOLUTION: A grain component sensor has a white LED 17 for emitting white light as a light source, a sample holder 8 which is filled with a sample 9, a spectroscope 11 for receiving reflected light from the sample, and performing spectroscopic analysis, and an optical filter 21 which is provided on an optical path between the while LED and the sample holder, wherein the optical filter has optical characteristics such that transmittance at a wavelength band of 950-1100 nm is approximately 100% and light of a visible light region is reduced to approximately 0%, the light emitted from the white LED transmits through the optical filter and is emitted to the sample as detected light of a wavelength band of 950-1100 nm, and diffused and reflected light from the sample is condensed by a condenser lens 24, and is incident on the spectroscope.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a grain component sensor and a grain component analyzer for analyzing components contained in grains by spectroscopy.

Background Art

[0002] There is known an analyzer that optically analyzes components contained in grains with the grains as a measurement target.

[0003] In recent years, some agricultural machines such as combines are equipped with GNSS sensors so that the position information of the heavy machine during operation can be obtained.

[0004] By mounting a grain component analyzer on an agricultural machine, acquiring quality data such as the protein and moisture content of the grains during harvesting in real time, and associating the acquired data with the position information of the field, it is possible to adjust the amount of fertilizer applied or improve the soil, and it can be used for an agricultural management plan to efficiently produce high-quality and consistent-quality crops.

[0005] Therefore, mounting a grain component analyzer on an agricultural machine is useful for the development of agriculture.

[0006] Conventionally, as a grain component analyzer, there is a grain component analyzer that irradiates grains with near-infrared light and detects the light absorption amount in the wavelength bands peculiar to water molecules and molecules constituting proteins to measure the moisture content and protein content.

[0007] As shown in FIG. 6, a conventional grain component analyzer includes a light source unit 30, a measurement optical system 31, and a spectroscope 32, and a halogen lamp is used as the light source.

[0008] Light emitted from the light source unit 30 (halogen lamp) is guided by the optical fiber 33 to the measurement optical system 31, and from the measurement optical system 31, it is irradiated onto the object to be measured (not shown) as measurement light e. The measurement light 34 (reflection ranging light 34') reflected by the object to be measured is received by the measurement optical system 31 and incident on the spectrometer 32 via the optical fiber 35. The spectrometer 32 performs optical analysis on the reflection ranging light 34' to detect the amount of light absorption in a specific wavelength band and measures the protein and moisture content of the grain.

[0009] The halogen lamp used in the above-mentioned grain component analyzer generates a high amount of heat and consumes a high amount of power. Therefore, a structure that blocks heat and dissipates heat is required to prevent the heat from affecting the measurement. The light source unit 30, the measurement optical system 31, and the spectrometer 32 are configured to be separate and independent, and each unit is connected by the optical fibers 33 and 35. For this reason, there was a problem in miniaturizing the grain component analyzer.

[0010] Furthermore, halogen lamps are expensive and have a short lifespan, requiring frequent replacement, which contributes to increased maintenance fees and running costs. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2016-114488 [Patent Document 2] Japanese Patent Publication No. 2016-133473 [Patent Document 3] Japanese Patent Publication No. 2019-198334 [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention provides a compact grain component sensor and grain component analyzer that can reduce maintenance fees and running costs. [Means for solving the problem]

[0013] The present invention relates to a grain component sensor comprising a white LED that emits white light as a light source, a sample holder filled with a sample, a spectrometer that receives reflected light from the sample and performs spectroscopic analysis, and an optical filter provided in the optical path between the white LED and the sample holder, wherein the optical filter has optical properties that provide approximately 100% transmittance in the wavelength band of 950 nm to 1100 nm and cut light in the visible light band to approximately 0%, the light emitted from the white LED passes through the optical filter and is irradiated onto the sample as detection light in the wavelength band of 950 nm to 1100 nm, the diffusely reflected light from the sample is focused by a focusing lens and incident on the spectrometer.

[0014] Furthermore, the present invention relates to a grain component sensor configured such that a light absorbing plate is provided on the reflected optical axis of the optical filter, and the light reflected by the optical filter is absorbed.

[0015] The present invention further comprises a calibration unit, the calibration unit including a standard white reflector and a white plate insertion / removal unit, the white plate insertion / removal unit being configured to allow the standard white reflector to be inserted and removed from the optical path between the optical filter and the sample holder.

[0016] Furthermore, the present invention relates to a grain component sensor in which the light source, spectrometer, optical filter, and calibration unit are housed in a sensor case, and the sample holder is detachable from the sensor case.

[0017] Furthermore, the present invention relates to a grain component analyzer comprising any of the above-mentioned grain component sensors, a control unit, a storage unit, a display unit, and a power supply unit, wherein the power supply unit supplies the required power to the grain component sensor, the control unit, the storage unit, and the display unit, and the control unit performs spectral measurement of the grain component sensor based on a program stored in the storage unit, acquires a reflectance-diffusion spectrum based on the obtained spectral data, and displays the reflectance-diffusion spectrum, spectral data, and calculation results on the display unit. [Effects of the Invention]

[0018] According to the present invention, there are provided a white LED that emits white light as a light source, a sample holder filled with a sample, a spectroscope that receives reflected light from the sample and performs spectroscopic analysis, and an optical filter provided on the optical path between the white LED and the sample holder. The optical filter has an optical characteristic that the transmittance in the wavelength band of 950 nm to 1100 nm is approximately 100% and cuts off light in the visible light range to approximately 0%. The light emitted from the white LED passes through the optical filter and is irradiated onto the sample as detection light in the wavelength band of 950 nm to 1100 nm. The diffusely reflected light from the sample is collected by a condenser lens and enters the spectroscope. Therefore, the light source can be miniaturized, and further, the grain component analyzer can be miniaturized, power can be saved, the lifespan can be extended, and excellent effects such as reduction of maintenance fee and running cost can be achieved.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic configuration diagram of a grain component analyzer according to an embodiment of the present invention. [Figure 2] It is a graph showing the optical characteristics (wavelength transmission characteristics) of the optical filter of this embodiment. [Figure 3] It is a graph showing the light attenuation effect of the optical filter. [Figure 4] It shows the reflection spectroscopic data during calibration and the reflection spectroscopic data during actual measurement. [Figure 5] It is a graph showing the analysis data of this embodiment and the analysis data of the conventional type. [Figure 6] It is a schematic diagram of a conventional grain component analyzer.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] FIG. 1 shows the schematic configuration of a grain component analyzer 1 according to this embodiment.

[0022] In the diagram, 2 is the housing, and a component detection sensor 3, a control unit 4, a storage unit 5, a power supply unit 6, a display unit 7, etc. are installed inside the housing 2. The power supply unit 6 supplies the required power to the component detection sensor 3, the control unit 4, the display unit 7, etc.

[0023] The memory unit 5 stores various programs for the grain component analyzer 1 to perform spectroscopic measurements, a program for calculating the water content, protein content, etc., based on the spectroscopic data obtained from the spectroscopic measurements, and the memory unit 5 also stores the spectroscopic data obtained from the spectroscopic measurements.

[0024] The control unit 4 executes the program stored in the memory unit 5 and performs the necessary control of the spectrometer 11, the calibration unit 14, the driver 18, etc., at the necessary timing.

[0025] Furthermore, the memory unit 5 may include semiconductor memory such as RAM, ROM, FlashROM, or DRAM, or magnetic recording memory such as an HDD. The control unit 4 may include a CPU specifically designed for this embodiment, or a general-purpose CPU, embedded CPU, microprocessor, etc.

[0026] The component detection sensor 3 is provided with a sample holder 8. The sample holder 8 may be fixedly attached to the component detection sensor 3 or may be detachably attached.

[0027] The sample holder 8 is filled with the sample to be measured (sample) 9, and when the sample holder 8 is fixedly mounted to the component detection sensor 3, the sample 9 can be filled into the sample holder 8 from outside the grain component analyzer 1 and can also be discharged from the sample holder 8.

[0028] Furthermore, if the sample holder 8 is detachable from the component detection sensor 3, the sample holder 8 filled with the sample 9 is attached to the component detection sensor 3 at the start of measurement, and the sample holder 8 is removed from the component detection sensor 3 when the measurement is completed.

[0029] Furthermore, by preparing multiple sample holders 8 pre-filled with samples and replacing the sample holder 8 after each measurement is completed, measurements can be performed efficiently.

[0030] The sample holder 8 has an incident window 10 into which detection light enters, and the incident window 10 is sealed with a transparent plate such as a glass plate. Alternatively, the entire sample holder 8 may be made of a transparent material.

[0031] Next, the component detection sensor 3 will be described.

[0032] The component detection sensor 3 mainly comprises a spectrometer 11, a light source unit 12, a light receiving unit 13, and a calibration unit 14. The spectrometer 11, the light source unit 12, the light receiving unit 13, and the calibration unit 14 may be housed in a sensor case 15, thereby unitizing the component detection sensor 3. In this case, the sample holder 8 may be detachable from the sensor case 15, or detachable from the housing 2.

[0033] The spectrometer 11, the light source unit 12, the light receiving unit 13, and the calibration unit 14 are each supplied with power from the power supply unit 6.

[0034] The spectrometer 11 has an energy-dispersive Si detector using a Si single crystal as the detection element, and performs spectroscopic analysis of the light received by the detection element. The range that can be analyzed by the Si detector is near-infrared light with a wavelength of 1100 nm or less.

[0035] The light source unit 12 includes a white LED 17 that emits white light and a driver 18 that causes the white LED 17 to emit light. Power is supplied to the driver 18 from the power supply unit 6, and the light emission is controlled by the control unit 4.

[0036] An optical filter 21 is arranged on the optical path (optical axis) of the white LED 17. As will be described later, the optical filter 21 has optical properties that block or attenuate light in the visible light range and transmit wavelengths necessary for component detection.

[0037] The white LED 17 can be a commercially available white LED 17, in which the light-emitting element and lens are integrated, and the light beam from the light-emitting element is set to be parallel light or have a predetermined divergence angle. Furthermore, in this embodiment, the projection distance to the sample can be shortened, so that the light emitted from the white LED 17 can be directly irradiated onto the sample 9 without passing through an optical system such as a lens. Therefore, in this embodiment, the light projection optical system can be omitted.

[0038] Next, in this example, water molecules and protein-constituting molecules contained in the sample are detected by spectroscopic analysis.

[0039] Water exhibits relatively strong absorption at 1940 nm, 1450 nm, 1190 nm, 970 nm, and 760 nm. Proteins, on the other hand, show complex spectra with overlapping absorption from various functional groups, but they are known to have characteristic absorption bands at 2180 nm and 2050 nm.

[0040] Therefore, it is preferable to use long wavelengths of 1000 nm or more for near-infrared spectroscopy, but expensive InGaAs detectors must be used in this wavelength range. Thus, in this embodiment, near-infrared spectroscopy is performed using a wavelength range of 1100 nm or less, enabling the use of a Si detector.

[0041] The white LED 17 emits white light, which includes almost the entire wavelength range. It is preferable to block out light other than the wavelength range necessary for component detection. Also, a characteristic of white LEDs is that the output in the wavelength range longer than the infrared range (900 nm) is significantly smaller than that in the visible range (for example, 1 / 10), so it is necessary to avoid spectral sensitivity saturation in the visible light range.

[0042] Figure 2 is a graph showing the optical characteristics of the optical filter 21, where the vertical axis represents transmittance and the horizontal axis represents wavelength.

[0043] Furthermore, in Figure 2, curve A is the wavelength / transmittance curve required in this embodiment, and curve B is the wavelength / transmittance curve of the actual optical filter 21 used in this embodiment.

[0044] Curves A and B are nearly identical, and the optical filter 21 has a transmittance of approximately 100% in the wavelength range of 950 nm to 1100 nm used in this embodiment.

[0045] In other words, the optical filter 21 has optical properties that transmit approximately 100% of light in the wavelength range of 1100 nm to 950 nm and cut out approximately 0% of light in the wavelength range below 950 nm (visible light range).

[0046] In this embodiment, the optical properties of the optical filter 21 are set to a visible light transmittance of 2.5% and an infrared transmittance of approximately 100%. By allowing 2.5% transmission of visible light, optical analysis of molecules other than water molecules and protein molecules becomes possible, as will be described later.

[0047] Furthermore, the optimal transmittance of the optical filter 21 is thought to differ depending on the white LED 17 used, and is not limited to the above transmittance.

[0048] Therefore, the light irradiated onto the sample 9 is in the wavelength range of 1100 nm to 950 nm. By limiting the irradiated light to the wavelength band necessary for component detection, the signal-to-noise ratio of the detection results is improved. Furthermore, saturation of spectral sensitivity in the visible light range can be avoided.

[0049] The light 20 emitted from the white LED 17 passes through the optical filter 21 and then through the incident window 10 before irradiating the sample 9.

[0050] The optical filter 21 and the incident window 10 are tilted at a predetermined angle with respect to the optical axis of the white LED 17. This prevents light reflected by the optical filter 21 and the incident window 10 from entering the white LED 17, thereby preventing the light emission state of the white LED 17 from becoming unstable. In the illustration, the optical filter 21 and the incident window 10 are each tilted at 45° with respect to the optical axis, but the angle is not limited to this.

[0051] The optical filter 21 transmits wavelengths of 1100 nm or less, but simultaneously reflects white light on its surface. In this embodiment, a light absorbing plate 23 is provided on the reflected light axis of the white light. The light absorbing plate 23 absorbs the light reflected from the optical filter 21. The light absorbing plate 23 prevents the light reflected by the optical filter 21 from being diffusely reflected inside the housing 2 and affecting the detection result by the spectrometer 11.

[0052] The diffusely reflected light from the sample 9 is focused by the focusing lens 24 and incident on the spectrometer 11.

[0053] The spectrometer 11 performs optical analysis on the incident reflected light and outputs the spectral data to the control unit 4.

[0054] The control unit 4 acquires a reflectance-diffusion spectrum based on the spectral data, and further calculates the water and protein content. The reflectance-diffusion spectrum, spectral data, calculation results such as protein content and water content are then displayed on the display unit 7.

[0055] Next, in this embodiment, the calibration unit 14 is provided to ensure measurement accuracy.

[0056] The calibration unit 14 includes at least a standard white reflector 25 and a white plate insertion / removal unit 26.

[0057] The white plate insertion / removal unit 26 inserts and removes the standard white reflector 25 into the optical path emitted from the white LED 17. Before and after the component analysis of the sample 9, or either before or after, or at predetermined intervals, the standard white reflector 25 is inserted into the optical path, the light 20 is irradiated onto the standard white reflector 25, and the reflected light from the standard white reflector 25 is detected by the spectrometer 11 as a reference light for calibration. The driving and timing of the white plate insertion / removal unit 26 are controlled by the control unit 4.

[0058] Next, the relationship between the optical filter 21 and the standard white reflector 25 will be explained.

[0059] As described above, this embodiment requires light in the wavelength range of 950 nm to 1100 nm (especially 1000 nm to 1100 nm). If the white LED 17 is made to emit light in such a way that the light intensity in this wavelength range is suitable for measurement, the light intensity in the visible region (wavelengths below 950 nm) becomes strong, causing the photodetector of the spectrometer 11 to saturate.

[0060] Figure 3 shows the reflection spectral data of the standard white reflector 25 obtained by inserting the standard white reflector 25 into the optical path. In Figure 3, the vertical axis represents the intensity of the received light signal, and the horizontal axis represents the wavelength. Also, in the figure, curve A represents the reflection spectral data without the optical filter 21, and the photodetector is saturated at wavelengths below 950 nm.

[0061] Next, curve B shows the reflection spectral data of a standard white reflector when light 20 is irradiated through the optical filter 21. This shows that by providing the optical filter 21, reflection spectral data could be obtained without saturation across the entire wavelength range.

[0062] Figure 4 shows the reflection spectral data from a standard white reflector with the optical filter 21 installed, as curve A, and the reflection spectral data from sample 9 (wheat in this embodiment) as curve B. In Figure 4, the vertical axis represents the intensity of the received light signal, and the horizontal axis represents the wavelength.

[0063] Curve A shows the reflection spectral data under calibration conditions.

[0064] Curve B shows that the reflected light from the sample also provides the necessary light intensity for measurement across the entire wavelength range, demonstrating the effectiveness of the optical filter 21. Therefore, the combination of the white LED 17 and the optical filter 21 makes it possible to perform component analysis on measurement targets other than grains.

[0065] Figure 5 shows the measurement results of a conventional grain component analyzer using a halogen lamp and the grain component analyzer according to this embodiment. In Figure 5, the vertical axis represents relative reflectance and the horizontal axis represents wavelength. Here, relative reflectance is expressed as a percentage of how much of the light energy emitted from the colorimeter is reflected back by the test surface relative to the reference surface.

[0066] With wheat as the object of measurement, curve A represents the analysis data from a conventional grain component analyzer, and curve B represents the analysis data from the grain component analyzer of this embodiment.

[0067] Although the measurement timing and samples differ, making a direct comparison difficult, the curve shapes are roughly identical, indicating the usefulness of the measurement method using the grain component analyzer in this embodiment.

[0068] As described above, this embodiment uses a white LED 17 as the light source. The white LED 17 used has a small external size of approximately 5 x 5 x 5.5 (mm) and a power consumption of 2.3W. Its lifespan is approximately 40,000 hours.

[0069] The halogen lamp consumes 100W, and the power supply unit, taking into account the heat dissipation of the halogen lamp, measures approximately φ50 x 45mm. The halogen lamp has a lifespan of about 1000 hours.

[0070] Therefore, in this embodiment, the light source itself is small, the power consumption is 0.28W, the heat generation is significantly low, and there is no need for a special heat dissipation structure, so the light source unit can be made significantly smaller. Furthermore, since the spectrometer 11, control unit 4, memory unit 5, and display unit 7 do not need to be separated and can be integrated, the grain component analyzer 1 can be made smaller and lighter.

[0071] Furthermore, since the lifespan of the white LED 17 is significantly longer than that of halogen lamps, maintenance fees and running costs can be reduced.

[0072] In this embodiment, the grain component sensor and grain component analyzer can be made smaller, lighter, and integrated, and since they consume little power, they can be easily mounted on mobile machinery such as agricultural machinery. [Explanation of symbols]

[0073] 1 Grain component analyzer 2 cabinets 3-component detection sensor 4. Control Unit 5 Storage section 6 Power supply section 7 Display section 8. Sample holder 9 samples 10. Entrance window 11 Spectrometer 14. Calibration section 17 White LED 18 Drivers 21 Optical filters 23 Light-absorbing plate 24 Focusing lenses 25 Standard white reflector 26 White plate insertion / removal part

Claims

1. a white LED that emits white light as a light source; a sample holder in which a sample is filled; a spectrometer that receives reflected light from the sample and performs spectroscopic analysis; and an optical filter that is provided on the light path between the white LED and the sample holder, the optical filter having optical properties of approximately 100% transmittance in the wavelength band of 950 nm to 1100 nm and cutting light in the visible light range to approximately 0%, the light emitted from the white LED passing through the optical filter and irradiating the sample as detection light in the wavelength band of 950 nm to 1100 nm, and the diffuse reflected light from the sample being collected by a collecting lens and entering the spectrometer.

2. 2. The grain component sensor according to claim 1, wherein a light absorbing plate is provided on the axis of light reflected by said optical filter so as to absorb the light reflected by said optical filter.

3. 2. The grain component sensor according to claim 1, further comprising a calibration unit including a standard white reflector and a white plate insertion / removal unit, the white plate insertion / removal unit being configured to be able to insert and remove the standard white reflector onto the optical path between the optical filter and the sample holder.

4. 4. The grain component sensor according to claim 3, wherein the light source, the spectroscope, the optical filter, and the calibration unit are housed in a sensor case, and the sample holder is detachable from the sensor case.

5. A grain component analysis device comprising a grain component sensor according to any one of claims 1 to 4, a control unit, a memory unit, a display unit, and a power supply unit, wherein the power supply unit supplies the required power to the grain component sensor, the control unit, the memory unit, and the display unit, and the control unit performs spectroscopic measurement of the grain component sensor based on a program stored in the memory unit, obtains a reflection diffuse spectrum based on the obtained spectroscopic data, and displays the reflection diffuse spectrum, the spectroscopic data, and the calculation results on the display unit.

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