JP2001021488A - Spectroscopic sensor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive light receiving sensor unit excellent in efficiency not requiring the correction of the measured value between light receiving elements by receiving the reflected light taken in a plurality of fiber heads by one light receiving element. SOLUTION: Branched fiber cables 3 are arranged between the rear ends of the fiber cables 2 connected to a plurality of fiber heads 1 and a light receiving element 4 and a rotary shutter 10 for successively selecting the fiber heads 1 is arranged between the rear ends of the fiber cables 2 and the leading ends of the branched fiber cables 3. A rotary filter 20 is arranged between the rear ends of the branched fiber cables 3 and the light receiving element 4. A plurality of filters 23 with different wavelengths are provided in the rotary filter 20 in the circumferential direction thereof at a predetermined interval and the rotary filter 20 is allowed to make one revolution during a period when the rotary shutter 10 selects one fiber head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectroscopic sensor unit which takes in reflected light of an object to be measured distributed over a wide range with a plurality of fiber heads and performs spectroscopic analysis.

[0002]

2. Description of the Related Art Conventionally, when spectroscopic analysis of the reflected light of a plant (object to be measured) is performed to observe the growth state of the plant, a helicopter or a balloon is used where the object to be measured is widely distributed. There are a method of taking a picture with a special camera from a high place, and a method of manually measuring each leaf of a plant with a transmitted light sensor.

[0003]

However, the former has a drawback that it takes time and expense to prepare the equipment and cannot perform continuous measurement, and the latter has a great deal of manpower and time and is difficult to measure over a wide range. .

[0004] The present invention solves the above-mentioned problems, and it is possible to obtain highly efficient and continuous spectral characteristic data by receiving reflected light captured by a plurality of fiber heads through a plurality of spectral filters with a single light receiving element. It is an object of the present invention to provide a low-cost and high-efficiency spectral sensor unit that does not require correction of measured values between light receiving elements.

In particular, by attaching the spectral sensor unit of the present invention to a moving device such as a tractor, it becomes possible to automatically collect a wide range of spectral data.

[0006]

According to a first aspect of the present invention, there is provided a spectroscopic sensor unit having the following requirements. (A) A plurality of fiber heads for taking in the reflected light of the light source reflected by the object to be measured, and fiber cables respectively connected to the fiber heads and guiding the reflected light to the light receiving element. (B) A rear end of the fiber cable. Between the light receiving element and the light-receiving element, the tip is branched in the same number as the fiber cable.
Two branch fiber cables are arranged, and the front ends of the branch fiber cables respectively oppose the rear ends of the fiber cables at a predetermined interval, and the rear ends of the branch fiber cables oppose the light receiving elements at a predetermined interval. (C) A rotary shutter for sequentially selecting a fiber cable is rotatably arranged between the rear end of the fiber cable and the front end of the branch fiber cable, and the rear end of the branch fiber cable and the light receiving element (D) a plurality of openings are formed in the rotation filter at predetermined intervals in a circumferential direction, and the openings have different wavelengths from each other. (E) The rotation of the rotating filter and the rotating shutter is synchronized, and the rotating The rotary filter to be rotated 1 while the shutter has selected one fiber cable

[0007] A spectral sensor unit according to a second aspect is characterized by having the following requirements. (B) a plurality of paired fiber heads for capturing the reflected light of the light source reflected by the object as visible light and near-infrared light;
A fiber cable connected to the fiber head for guiding the reflected light to the light receiving element; (b) between the rear end of the fiber cable and the light receiving element, the front end is branched into half of the fiber cable;
Two branch fiber cables are arranged, and the front ends of the branch fiber cables respectively oppose the rear ends of the fiber cables at predetermined intervals, and the rear ends of the branch fiber cables are respectively a visible light receiving element and a near infrared light. (C) a pair of fiber heads are simultaneously selected between the rear end of the fiber cable and the front end of the branch fiber cable, and the other pair of fibers is provided. A rotating shutter that selects the head in order is rotatably arranged,
A rotary filter is rotatably arranged between the rear end of the branch fiber cable and the light receiving element. (D) A plurality of openings are formed in the rotary filter at predetermined intervals in a circumferential direction. And a filter having a different wavelength corresponding to visible light and near-infrared light is provided in each of the openings. (E) The rotation of the rotation filter and the rotation of the rotation shutter are synchronized, and the rotation of the rotation shutter is One rotation of the rotary filter while selecting a pair of fiber heads

The rotary shutter closes an opening at a position facing the light receiving element of the rotary filter when the rotary shutter switches the selection from the previous-stage fiber head to the subsequent-stage fiber head. At the position of the rotary filter in the transitional transition state, the reflected light may be blocked by the light receiving element.

[0009] At least one front surface of the fiber head may be provided with a reflector for directly reflecting light from a light source to the fiber head.

[0010]

FIG. 1 is a block diagram of a spectroscopic sensor unit according to the present invention. In the spectroscopic sensor unit, a fiber cable 2 is connected to a plurality of fiber heads 1 and guided by each fiber cable 2. The detected light is guided to one light receiving element 4 by a branch fiber cable 3, and a light receiving signal output from the light receiving element 4 is analyzed by a detection circuit 5, converted into digital data, and transmitted to a control unit (not shown). The present invention can be applied to a system that can measure the growth state of a crop by spectroscopic analysis of sunlight reflected by the crop.

The fiber head 1 is supported by a support member (not shown) at a predetermined interval so as to take in the reflected light b reflected by an object to be measured (for example, vegetables or the like) a. Are connected to the ends of fiber cables 2a to 2e, respectively, and the rear ends of the fiber cables 2a to 2e are connected to an opening 7 formed on one surface of a sealed housing 6 to prevent external light from entering. Socket 8 fitted so as to protrude into housing 6
It is connected to the. The opening 7 (socket 8)
Are formed at equal intervals on the same circumference.

As shown in FIG. 2, the branch fiber cable 3 has a distal end branched into five, and the light entering from the distal end can be condensed into one at the rear end.
e respectively face the rear ends (sockets 8a to 8e) of the fiber cable 2 at a predetermined interval,
The rear end 3f is arranged to face the light receiving element 4 at a predetermined interval.

The rotary shutter 10 is composed of a rotary disk, and is disposed between the rear end of the fiber cable 2 and the front end of the branch fiber cable 3. As shown in FIG. 3A, a part (1/5) of the periphery of the rotary shutter 10 is cut out in a fan shape, and only the detection light of the fiber cable 2 selected by the cutout 11 rotates. The fiber cable 2 can pass the detection light only for 1/5 of the time that the rotary shutter 10 makes one rotation. This rotating shutter 1
A spur gear 13 is fixed to the 0 rotation shaft 12, and this spur gear 13 meshes with a gear 15 fixed to one end of an output shaft protruding forward and backward of the motor 14, and is decelerated in conjunction with rotation of the motor 14. It is designed to rotate. The gear 15 and the spur gear 1 rotate so that the rotation shutter 10 (spur gear 13) rotates １ ／ when the output shaft (gear 15) makes one rotation.
A gear ratio of 3 is set. In the present invention, the output shaft of the motor 14 is controlled to rotate 24 times per second.

The rotary filter 20 is composed of a rotating disk.
It is arranged between the rear end 3 f of the branch fiber cable 3 and the light receiving element 4. The center of the rotary filter 20 is fixed to the other end of the output shaft of the motor 14 and the five openings 2
One and one balancer 22 are arranged at equal intervals in the circumferential direction (see FIG. 3B), and filters 23a to 23e having different wavelengths are fitted into the opening 21, respectively. When the motor 20 rotates once, all the filters 23a to 23e can pass between the rear end 3f of the branch fiber cable 3 and the light receiving element 4. The balancer 22 is provided to balance the rotation filter 20 so that the rotation filter 20 can rotate smoothly.

Further, the position of the balancer 22 is a time zone in which the detection light does not pass, and as shown in the time chart of FIG. When passing through the cable 2, the passing light falls and rises. The falling light and the rising light are overlapped so that the detection light can be taken from the fiber cable 2 for as long as possible. Since the detection light is sent from the two fiber cables 2 to the light receiving element 4 at the same time, a balancer is provided instead of the filter, and the filter serves as a shutter so that the detection light does not pass.
The rotation of 0 is smoothed. If the balancer 22 is not provided as described above, the filters 23a to 23a
When the filters 23a to 23e are arranged at equal intervals, it is necessary to widen the respective intervals of the filters 23a to 23e while avoiding the above-mentioned overlap time.
Is more than twice as large.

The light receiving element 4 is for detecting visible light and includes Si
A photodiode is used, and five light receiving signals d1 to d5 are continuously output by receiving light transmitted through five filters 23a to 23e having different wavelengths provided in the rotation filter 20. is there.

According to the spectral sensor unit having the above configuration,
The reflected light b reflected by the device under test a is taken into the fiber cable 2 through the fiber head 1, and the taken-in reflected light reaches the other end from one end of the fiber cable 2 and reaches the rotary shutter 10 from the other end. It is emitted as detection light. At this time, since the motor 14 is rotating, the rotary shutter 10 is rotating at a constant speed via the gear 15 and the spur gear 13.
Since the fan-shaped notch 11 is formed at 0, only the detection light of the fiber cable 2 corresponding to the notch 11 passes through the rotary shutter 10 and reaches the tip of the opposing branch fiber cable 3, It passes through the branch fiber cable 3 and reaches the rear end 3f of the branch fiber cable 3.

The detection light that has reached the rear end is rotated by the rotation filter 20.
To the rotating filter 20.
Is rotated by a motor 14, and the rotation is synchronized with the rotation of the rotary shutter 10.
One rotation while one fiber cable 2 is selected. Since the filters 23a to 23e having five different wavelengths are attached to the rotary filter 20, the detection light passes through the filters 23a to 23e and reaches the light receiving element 4.

The detection light reaching the light receiving element 4 is converted into light receiving signals d1 to d5 by the light receiving element 4 and converted into digital signals by the detection circuit 5 as shown in FIG. And transmitted to a processing device (not shown).

In FIG. 1, reference numeral 25 denotes a reflector, which has a uniform reflectance within the wavelength of light to be observed. Since the gain of the reflected light at each measurement wavelength changes depending on the weather and the weather, it is necessary to normalize the gain. However, the normalization can be performed by comparing the gain with the reflected light of the reflector 25. The reflection plate 25 may be provided rotatably with respect to all the fiber heads 1. After the reflected light is captured by the reflection plate at the initial stage, the reflection plate 25 may be rotated and retracted so as to capture the reflected light of the object to be measured. Alternatively, one fiber head may be used for correction and the reflector may be fixed. In FIG. 1, reference numeral 26 denotes a power cable, 2
Reference numeral 7 denotes a stabilized power supply.

As described above, the detection light captured by the plurality of fiber heads can be processed by one light receiving element by the rotating shutter and the rotating filter which are rotated in synchronization. It is possible to reduce the manufacturing cost as compared with the case where the optical sensor is provided, and it is possible to realize a spectroscopic sensor unit that is excellent in handling because it is not necessary to correct a variation in measured values due to a difference in characteristics of the light receiving element.

That is, as described above, the spectral sensor unit of the present invention can simultaneously take in spectral data from a plurality of fiber heads. Therefore, this fiber head is disposed on a long arm at a predetermined interval, and By moving the tractor laterally from the side of the tractor-like moving device, spectral data in a wide range can be collected extremely efficiently.

It is needless to say that the number of fiber heads and the number of branch fiber cables are not limited to the above numbers.

Next, a spectroscopic sensor unit that measures visible light and near-infrared light using two light receiving elements will be described.

As shown in FIG. 5, this spectroscopic sensor unit is so constructed as to be able to simultaneously take in the reflected light b1 for visible light analysis and the reflected light b2 for near-infrared light analysis from the reflected light of the same object a. A set of two fiber heads, a fiber head 31 for light and a fiber head 32 for near-infrared light, is provided as a set, and three sets of fiber heads are arranged at a predetermined interval on a support member (not shown). For example, it is possible to take in reflected light reflected by a), and each of the fiber heads 31a to 31c, 32a to 32
c are fiber cables 33a to 33c, 3 respectively.
The ends of the fiber cables 4a to 34c are connected, and the rear end of each fiber cable is formed in an opening 7 formed on one surface of a sealed housing 6 so that external light does not enter. Are connected to the sockets 35 and 36 fitted in the.

The sockets 35a to 35c, 36
a to 36c are arranged at equal intervals on the same circumference, and fiber cables 31a to 31c for visible light are sequentially connected to sockets 35a to 35c, and then fiber cables 32a to 32c for near infrared light. Are in turn socket 36
a to 36c.

As shown in FIG. 6, the branch fiber cables 37 and 38 are such that the distal end is branched into three, and the light entering from the distal end can be collected into one at the rear end. Two branch fiber cables 3 for near infrared light
7 and 38 are disposed, and each end is a rear end of a fiber cable for visible light and near infrared light (socket 35,
36) at a predetermined interval, and the rear end of the branch fiber cable 37 is connected to a light receiving element 40 for visible light.
The rear end of the branch fiber cable 38 is disposed so as to face the light receiving element 39 for near infrared light at a predetermined interval.

The rotary shutter 45 is composed of a rotary disk, and as shown in FIG. 7A, a fan-shaped opening 46 of 1/6 of the circumference and a timing mark 47 notched on the periphery.
Are formed symmetrically about the rotation axis 12 so that only the detection light of the fiber cables 31 and 32 selected at the opening 46 can pass through the rotation shutter 45.
Each fiber cable can pass the detection light only for 1/3 of the time during which the rotary shutter 45 rotates 1/2. This rotating shutter 4
A spur gear 13 is fixed to the rotary shaft 12 of the motor 5, and the spur gear 13 meshes with a gear 15 fixed to one end of an output shaft protruding forward and backward of the motor 14, and is decelerated in conjunction with the rotation of the motor 14. It is designed to rotate. The gear 15 and the spur gear 1 rotate so that the rotation shutter 45 (spur gear 13) rotates 1/6 when the output shaft (gear 15) makes one rotation.
A gear ratio of 3 is set. In the present invention, the motor 14 is constituted by a stepping motor, and the output shaft is controlled to rotate 24 times per second.

The timing mark 47 is detected by the timing sensor 48 to recognize the position of the fiber head (the position of the object to be measured).
When the timing mark 47 is detected, it can be determined that the fiber heads corresponding to the openings 46 of the rotary shutter 45 are the fiber heads 31a and 32a, and the subsequently detected fiber head is the fiber head 3.
1b, 32b and fiber heads 31c, 32c.

The rotary filter 50 is composed of two rotary disks 51 and 52 supported on the same axis, is disposed between the branch fiber cables 37 and 38 and the light receiving elements 39 and 40, and Is fixed to the other end of the output shaft. Openings 53a to 53c for the light receiving element 39 are formed on the first rotating disk 51 at predetermined intervals on the same circumference, and inside the opening, openings 54a to 54c for the light receiving element 40 are formed.
4c are formed at a predetermined interval on the same circumference, six timing marks 55a to 55f are formed on the periphery, and each opening 53a to 5f is formed on the second rotating disk 52.
3c, fitting holes 56 formed at positions corresponding to 54a to 54c have near-infrared light filters 57a to 57c having different wavelengths.
57c and filters 58a to 58 for visible light having different wavelengths.
The notches 59 are formed at six positions at positions corresponding to the timing marks 55a to 55f, respectively.

When the rotary filter 50 makes one rotation, all the filters 57a to 57c and 58a to 58c are connected to the branch fiber cables 37 and 38 and the light receiving elements 39 and 40.
It allows you to pass between and. Reference numeral 60 denotes a timing sensor for detecting the timing marks 55a to 55f, which specifies a filter and a light receiving element.

The light receiving element 39 for detecting near-infrared light is PbS
A light-receiving element 40 for detecting visible light may be used.
May use a Si photodiode.

According to the spectral sensor unit having the above structure,
The reflected light reflected by the object to be measured is
31c, 32a to 32c to fiber cable 33a
33c and 34a to 34c, the captured reflected light reaches the other end from one end of the fiber cable, and is irradiated from the other end toward the rotary shutter 45 as detection light.

At this time, since the motor 14 is rotating,
The rotary shutter 45 is rotating at a constant speed via the gear 15 and the spur gear 13, but since the rotary shutter 45 has a fan-shaped opening 46, the opening 46 detects the corresponding fiber cable. Branch fiber cable 3 where only light passes through rotating shutter 46 and faces
7 and 38, reach the tip and branch fiber cable 3
It passes through 7, 38 and reaches the rear end.

The detection light reaching the rear end is supplied to the rotary filter 50.
Irradiates the rotating filter 50.
9A to 9G, at the position where the timing sensor 60 detects the timing marks 55a to 55f, the filters 57a to 57c for near-infrared light are provided to the light receiving element 39 and to the visible light. The filters 58a to 58c are the light receiving elements 4
0, and the rotation is synchronized with the rotation of the rotary shutter 45. Therefore, the rotary shutter selects a pair of near infrared light fiber head and visible light fiber head. During one rotation, the detection light passes through the filters 57a to 57c and 58a to 58c alternately and sequentially and reaches the light receiving elements 39 and 40.

The detection light having reached the light receiving elements 39 and 40 is the light receiving elements 39 and 40, and as shown in FIG. 8, the PbS signals (d1, d3, d4) and the Si signals (d2, d4, d6).
, And the two signals are combined to form a total signal, which is converted into a digital signal by the detection circuit 5, and then transmitted to a processing device (not shown) via the signal cable 24.

The timing signals t1 to t6 generated by the timing marks determine the timing of sampling the light receiving signal, and include the first timing mark 55a (timing signal t1) and the last timing mark 55f (timing signal t6). )
Since the interval is set to twice the interval between other timing marks (timing signals), the timing signal first detected by the timing sensor 60 after a long time becomes the timing signal t1 by the timing mark 55a. I have.

The light receiving signals d1 to d6 can be specified by timing signals t1 to t6. For example, the light receiving signal output at the timing of the timing signal t1 passes through the near-infrared light filter 57a and
9 (see FIG. 9B), and the light receiving signal output at the timing of the timing signal t2 passes through the visible light filter 58a and is received by the light receiving element 40 (FIG. 9C). See).

[0039]

According to the first aspect of the present invention, the detection light captured by the plurality of fiber heads can be processed by one light receiving element by the rotary shutter and the rotary filter rotated in synchronization. As a result, the efficiency can be greatly improved as compared with the conventional measurement method, and the manufacturing cost can be reduced as compared with the case where a plurality of light receiving elements are provided. It is possible to realize a spectroscopic sensor unit that is excellent in handling without having to correct the variation of the spectral sensor.

According to the second aspect of the present invention, the reflected light of the object to be measured is separated into visible light and near-infrared light, and the separated visible light and near-infrared light are received by different light receiving elements. By doing so, a large spectral signal can be obtained from reflected light that is weaker than the spectral sensor unit that measures light with a single light receiving element, and when used outdoors, even when it is sunny, cloudy, and when morning and evening sunlight is weak A spectroscopic sensor unit capable of performing measurement can be realized.

According to the third aspect of the invention, the size of the rotary filter can be reduced, and the interval between the filters can be narrowed, so that the entire measurement time can be shortened and the measurement efficiency can be improved. it can.

According to the fourth aspect of the present invention, when sunlight is used as a light source in an outdoor environment, normalization is performed by comparing sunlight reflected by a reflector with light reflected by an object to be measured. And stable reflection spectral information can be obtained which is not affected by the intensity of sunlight which varies depending on the time zone (morning, noon, evening) and weather conditions (cloudy or fine weather).

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a spectral sensor unit according to the present invention.

FIG. 2 is a perspective view showing a configuration of the spectral sensor unit.

FIGS. 3A and 3B are front views of a rotary shutter and a rotary filter.

FIG. 4 is a time chart of the spectral sensor unit.

FIG. 5 is a configuration diagram showing another example of the spectral sensor unit.

FIG. 6 is a perspective view showing a main configuration of the spectroscopic unit of the another example.

FIGS. 7A and 7B are front views of another example of the spectral unit rotary shutter and the rotary filter.

FIG. 8 is a time chart of another example of the spectral sensor unit.

FIGS. 9A to 9G are explanatory diagrams showing a relationship between a rotation filter and a light receiving element of the another example of the spectral sensor unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber head 2 Fiber cable 3 Branch fiber cable 4 Light receiving element 10 Rotating shutter 20 Rotating filter 21 Opening 23 Filter 25 Reflector 31, 32 Fiber head 33, 34 Fiber cable 37, 38 Branch fiber cable 39, 40 Light receiving element 45 rotation Shutter 50 Rotary filter 57, 58 Filter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichi Ishizuka 1-2-8 Toranomon, Minato-ku, Tokyo Inside System Technology Co., Ltd. (72) Inventor Yasuo Ueno 2-3-9 Amanuma, Suginami-ku, Tokyo F-term in International Technology Development Co., Ltd. (reference) 2G020 AA03 AA04 CB42 CB43 CC26 CC48 CD03 CD12 CD24 DA53 2G059 AA05 BB11 EE02 HH01 HH02 JJ02 JJ17 KK01

Claims (4)

[Claims] 1. A spectral sensor unit having the following requirements. (A) A plurality of fiber heads for taking in the reflected light of the light source reflected by the object to be measured, and a fiber cable connected to each of the fiber heads and guiding the reflected light to the light receiving element. (B) A rear end of the fiber cable. Between the light receiving element and the light receiving element, the tip of which is branched in the same number as the fiber cable.
Two branch fiber cables are arranged, and the front ends of the branch fiber cables respectively oppose the rear end of the fiber cable at a predetermined interval, and the rear ends of the branch fiber cables oppose the light receiving element at a predetermined interval. (C) A rotary shutter for sequentially selecting a fiber head is rotatably arranged between the rear end of the fiber cable and the front end of the branch fiber cable, and the rear end of the branch fiber cable and the light receiving element (D) a plurality of openings are formed in the rotation filter at predetermined intervals in a circumferential direction, and the openings have different wavelengths from each other. (E) The rotation of the rotary filter and the rotary shutter is synchronized, and the rotation is The rotary filter to be rotated 1 while the Yatta has selected one fiber heads 2. A spectroscopic sensor unit having the following requirements. (B) a plurality of paired fiber heads for capturing the reflected light of the light source reflected by the object as visible light and near-infrared light;
A fiber cable connected to the fiber head for guiding the reflected light to the light receiving element; (b) between the rear end of the fiber cable and the light receiving element, the front end is branched into half of the fiber cable;
Two branch fiber cables are arranged, and the front ends of the branch fiber cables respectively oppose the rear ends of the fiber cables at predetermined intervals, and the rear ends of the branch fiber cables are respectively a visible light receiving element and a near infrared light. (C) a pair of fiber heads are simultaneously selected between the rear end of the fiber cable and the front end of the branch fiber cable, and the other pair of fibers is provided. A rotating shutter that selects the head in order is rotatably arranged,
A rotary filter is rotatably arranged between the rear end of the branch fiber cable and the light receiving element. (D) A plurality of openings are formed in the rotary filter at predetermined intervals in a circumferential direction. And a filter having a different wavelength corresponding to visible light and near-infrared light is provided in each of the openings. (E) The rotation of the rotation filter and the rotation of the rotation shutter are synchronized, and the rotation of the rotation shutter is One rotation of the rotary filter while selecting a pair of fiber heads 3. The rotating filter according to claim 1, wherein an opening is closed at a position facing the light receiving element of the rotary filter when the rotary shutter switches selection from a preceding fiber head to a subsequent fiber head. Spectroscopic sensor unit. 4. The spectral sensor unit according to claim 1, wherein a reflection plate for directly reflecting light of a light source to the fiber head is provided on at least one front surface of the fiber head.