JPH04116503A - Diffuse reflecting plate and diffuse reflecting plate group - Google Patents

Abstract

PURPOSE:To obtain the diffuse reflecting plate which is hardly damaged and not affected by temperature or humidity and reduced secular change by providing a metallic layer on another face so that light made incident from one face of a transmissive filter can be diffusely reflected on the other face of the filter. CONSTITUTION:A diffuse reflecting plate 1 is equipped with a transmissive filter 2 and a metallic layer 5 provided on another face 4 so that the light made incident from one face 3 of this filter 2 can be diffusely reflected on the other face 4 of the filter 2. The metallic layer 5 is formed by depositing aluminum after making the face 4 of the filter 2 coarse by scrubbing it by sand paper. Therefore, the light made incident from the face 3 is diffusely reflected by the aluminum depositing face (metallic layer 5) on the other face 4 of the filter 2. Thus, the diffuse reflecting plate can be obtained to be hardly damaged, not to be affected by temperature or humidity and to reduce the secular change.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a diffuse reflector and a group of diffuse reflectors, and more specifically, to the calibration (adjustment) of a measuring device having the function of spectrophotometrically measuring reflected light from a measurement target. The present invention relates to a diffuse reflector plate and a diffuse reflector group suitable for use.

[Prior Art] Conventionally, when measuring the characteristics of a spectrometer or adjusting the spectrometer, a reflector plate that can provide completely diffused light has been used. A typical example is a standard white surface.

The standard white surface consists of a barium sulfate crimped surface. The spectral reflectance of a standard white surface is high and constant from 0.970 to 0.985 over the entire measurement wavelength range.

A standard white surface is a reflective surface that approximates a perfectly diffuse reflective surface.

In addition to the standard white surface, there are regular standard white surfaces and reference white surfaces. A commonly used standard white surface is a reflective surface with excellent durability and a spectral reflectance of 0.900 or more over the entire measurement wavelength range. The spectral reflectance of a commonly used standard white surface is determined based on the standard white surface. The reference white surface is used as a reference when measuring using a two-light path spectrophotometer. The reference white surface is a reflective surface that has performance equivalent to the commonly used standard white surface. The spectral reflectance of the reference white surface does not need to be known.

Furthermore, Japanese Patent Laid-Open No. 131184/1984 discloses a reflector made of solidified alumina oxide (AR203) powder.

The above-mentioned white surface or reflective plate are both reflective surfaces having high reflectance.

[Problems to be Solved by the Invention] Standard white surfaces made of barium sulfate pressure bonded surfaces and reflectors made of hardened alumina oxide powder are fragile and easily damaged.

It is also highly hygroscopic and unstable over time.

Additionally, these white surfaces or reflectors have high reflectance. Commonly used standard white surfaces and reference white surfaces are ones that are hard to scratch, unaffected by temperature and humidity, and do not change over time, and these also have high reflectance. When using a reflective surface with a high reflectance to calibrate a measuring device that measures an object whose reflectance is not so high, there is a problem that it is difficult to ensure accurate calibration of such a measuring device. be. This is despite the fact that when measuring normal objects, the reflectance is measured within a predetermined range that is not very high (in other words, the reflectance of most objects is included in the predetermined range). However, this is because the calibration is performed using a reflective surface with a high reflectance that is outside this range.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, it is an object of the present invention to provide a diffuse reflection plate that is not affected by scratches, temperature or humidity, and exhibits extremely little change over time. A further object of the present invention is to provide a group of diffuse reflectors having various reflectances that can accurately calibrate a measuring device that measures a subject whose reflectance is not so high, for example.

[Means for Solving the Problems] In order to achieve the object described in item 1, the diffuse reflection plate according to the present invention has a structure in which light incident on one surface of a transmission filter is diffusely reflected on the other surface of the filter. It is characterized in that a metal layer is provided on the other surface so that the metal layer appears on the other surface.

Further, the diffuse reflection plate according to the present invention includes a transmission type filter having a substantially flat transmittance for light having a wavelength within a predetermined range, and a transmission type filter having a transmissive type filter having a substantially flat transmittance for light having a wavelength within a predetermined range. and a metal layer provided on the other surface so as to be diffusely reflected by the surface.

Furthermore, the diffuse reflector group according to the present invention is a diffuse reflector group consisting of a plurality of diffuse reflectors used for calibrating a measuring device having a function of spectrophotometrically measuring reflected light from an object to be measured. The diffuse reflector group is characterized by comprising a plurality of the above-mentioned diffuse reflectors configured using a plurality of transmission filters having different transmittances.

In the present invention, the term light includes not only visible light but also infrared and ultraviolet regions.

[Function] According to the above-described diffuse reflection plate according to the present invention, incident light enters from one surface of the transmission filter, passes through this filter, and is diffusely reflected by the metal layer provided on the other surface. . The diffusely reflected light passes through the filter again and exits from one surface of the filter as diffusely reflected light.

In the diffuse reflector according to the present invention, by using transmission filters with various transmittances, diffuse reflectors with various reflectances can be easily obtained. Therefore, when used for calibrating a measuring device that has the function of spectrophotometrically measuring reflected light from a measurement target, it is easy to use a diffuse reflector with a reflectance that is within the reflectance range of the object that the measuring device is measuring. It can be prepared at any time.

[Example code] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1(A) is a plan view of a diffusion anti-elbow plate according to an embodiment of the present invention, and FIG. 1(B) is a side view. This diffuse reflection plate 1
has a transmission filter 2 and a metal layer 5 provided on the other surface 4 so that light incident from one surface 3 of the filter 2 is diffusely reflected on the other surface 4 of the filter 2. .

Filter 2 used a commercially available neutral filter (ND filter). The metal layer 5 was formed by roughening the surface 4 of the filter 2 by rubbing it with sandpaper (matte finish), and then vapor depositing aluminum. Therefore, the light incident from the surface 3 is diffusely reflected by the aluminum vapor deposited surface (metal layer 5) on the other surface 4 of the filter 2. Note that the method for roughening the surface 4 of the filter 2 before depositing aluminum is not limited to this.

The diffuse reflection plate of this example is easily created by, for example, applying aluminum vapor deposition to a commercially available ND filter. There are ND filters with various transmittances. By using these ND filters with various transmittances, diffuse reflection plates with various reflectances can be easily obtained.

The ND filter has a substrate made of glass or plastic, for example, and is coated with various coatings. Therefore, the diffuse reflection plate of this example does not become brittle and collapse like a standard white surface. It is also less likely to get scratched. Furthermore, the reflectance changes little over time due to temperature and humidity.

Next, an example in which the above-mentioned diffuse reflection plate is applied to the calibration of a sugar content measuring device that measures sugar content by irradiating light onto a peach as an object and spectrophotometrically measuring the reflected light will be described.

FIG. 2 (A) is a plan view of a diffuse reflection plate used for calibrating the peach sugar content measuring device and a base for fixing the diffuse reflection plate;
FIG. 2(B) is a side view thereof.

In these figures, the same numbering as in FIG. 1 indicates common elements or parts. 6 is a base on which the diffuse reflection plate 1 is fixed. A cylindrical recess is provided on the upper surface of the base 6, and the diffuse reflection plate 1 is fixed to this recess as shown in the figure. The mounting direction of the diffuse reflection plate 1 is such that the metal layer 5 is on the side of the base 6,
In addition, the surface 3, which is the light incident surface, faces outward.

On the side of the base 6 opposite to the side where the diffuse reflection plate 1 is fixed,
A recess 7 for screwing is provided.

A side wall surface 8 (inside the base 6) of the recess 7 is threaded.

FIG. 3(A) is a plan view of a mounting tool for mounting the base 6 to which the diffuser reflecting plate 1 is fixed, and FIG. 3(B) is a side view thereof.

The mounting tool 10 has a flat plate portion 11 and an arm portion 12 provided at an end of the flat plate portion 11. A cylindrical protrusion 13 is provided on one surface of the flat plate portion 11 . The side wall 14 of the projection 13 is threaded. The recess 7 of the base 6 to which the diffuse reflection plate 1 of FIG. 2 is fixed and the mounting tool 1 of FIG. 3
0 and the protrusion 13 of the base 6 by screwing it together.
is fixed to the mounting tool 10.

FIG. 4 shows peaches whose sugar content is to be measured moving along a line. In the figure, the peach 23 placed on the conveyor 22 moves as indicated by the arrow. In the middle of this, a measuring section 1 housing 21 is placed. housing 2
An inlet part 24 is provided on the side wall of the measuring part 1, and the peach 23 placed on the conveyor 22 passes through the inlet part 24 to the housing 2 of the measuring part.
1 is introduced inside. Note that a similar outlet (not shown) is provided on the side wall of the housing 21 facing the artificial part 24.

25 is an opening for measuring the peach. No\Using 2
The peach 23 introduced into the interior of the peach 1 is irradiated with light from a light source 26 as shown by an arrow 27 through an opening 25. This light is reflected by a reflector 23 inside the housing 21, and reflected light 28 is generated. By measuring this reflected light 28, the sugar content of the peach 23 is derived.

The structure and operation of a measuring device (arranged to face the opening 25) that irradiates the peach with light 27 from the light source 26 and measures the reflected light 28 will be described later with reference to FIG. 5 and so on.

On the upper part of the housing 21 of the measurement unit, there is a mounting tool 10 equipped with the diffuse reflection plate 1 (on the base 6) described in FIG. 2.3.
A hole 29 is provided for inserting the. When calibrating (adjusting) the measuring device, the challenge 23 on the conhair 22 is removed, and the mounting tool 10 equipped with the diffuse reflection plate 1 is inserted into the two holes. The mounting tool 10 is attached to the attached diffuser reflector or the fourth
Insert it in the same direction as the light source 26 in the figure. The arm portion 12 of the mounting tool 10 is hooked to the edge of the hole 29 of the housing 21. As a result, the diffuse reflection plate 1 becomes the housing 2]
It will be located near where the inner challenger 23 is located. After arranging the diffuse reflection plate 1 in this way, from the light source 26 to the arrow 2
The sugar content measuring device is calibrated by emitting light as shown in 7 and measuring the reflected light 28 reflected by the diffuse reflection plate 1.

FIG. 5 shows a block configuration of a sugar content measuring device for measuring sugar content of peaches. In this figure, the same numbers as in FIG. 4 indicate common members. 31 is a spectroscope that separates the reflected light; 32 is a light receiving element that receives the separated light in each wavelength band and converts it into an electrical signal; 33 is an amplifier that amplifies the output signal of the light receiving element 32; (I10) It is an interface. In this example, the reflected light from the peach is divided into six wavelength bands (
In order to perform measurement by spectroscopy into 1 band), the light receiving element 32
It has a six-channel element that receives each of the six band lights.

Further, 35 is a central processing unit (CPU) that controls the operation of the entire measuring device, 36 is a random access memory (RAM) used for a work register, etc., and 37 is a CPU.
A read-only memory (ROM) stores programs executed by U35 and various constants, and 38 is a flexible disk (FD) device or hard disk (HD).
39 indicates a bidirectional pass line.

The RAM 36 is backed up by a battery (not shown). Therefore, even if the measuring device is switched off, the predetermined memory contents are retained.

A method for calculating sugar content in a peach sugar content measuring device as shown in FIG. 5 is disclosed in, for example, Japanese Patent Application Laid-Open No. 64-28544 and Special Vehicle No. 1-301147. In this embodiment, the system disclosed in Special Vehicles Publication No. 1-301147 is applied.

That is, using the apparatus shown in FIG. 5, from the light R26,
Light is radiated toward the target 23 which is being moved as shown in FIG. Then, the spectrometer 31 collects the reflected light 28 from six hands (hereinafter referred to as band B1).

B2. ..., called B6). Light receiving element 32
receives the reflected light from the peach in each of these six bands and converts it into an electrical signal. The output signal of the light receiving element 32 is input to the CPU 35 via the amplifier 33 and the I10 interface 34.

The CPU 35 calculates the reflectance of the peach from the reception results of the reflected light in these six bands, and calculates the estimated sugar content by substituting the reflectance into a predetermined model formula. Then, depending on the calculated estimated sugar content, it issues commands such as sorting the peaches on the conveyor by quality and moving them to another line.

By the way, with such peach sugar content measuring devices, there are machine differences between devices, differences in installation, and changes over time.

The machine difference is caused by, for example, variations in the characteristics of the light source 26, the spectrometer 31, or the light receiving element 32.

For example, even if two sugar content measuring devices measure the same peach, the luminous intensity of the light source 26 and the light receiving element 32 of the two sugar content measuring devices
If the sensitivities are different, the same result will not be obtained.

The installation difference is caused by, for example, variations in the distance between the sugar content measuring device and the measuring section 21 in FIG. 4. If there is a difference in the length of the optical path irradiated from the light source 26, reflected by the peach, and reaches the light-receiving element 32 due to the misalignment of the installation position of the apparatus, even if the same peach is measured, the same results will not be obtained.

The change over time is caused, for example, by a change in the characteristics of each member (eg, a light source and a light receiving element) constituting the device over time. Due to these differences in changes over time, there will be differences in measurement results even when measuring the same peach.

FIG. 6 shows how the measured values (actual values) of reflectance vary due to machine differences, installation differences, and changes over time between devices. The horizontal axis of the graph represents the wavelength, and the vertical axis represents the measured value (actual value) of reflectance. In each of the six breads FB1 to B6, the results of measuring one peach using the first measuring device are indicated by a triangle mark and △.

Similarly, the results of measuring the same peach with the second measuring device are shown with a rose mark (X), and the results of measuring the same peach with the third measuring device are shown with a circle mark (O).

As shown in the figure, there are differences in the reflectance measurement results due to machine differences between measuring devices, installation differences, and changes over time. Therefore, based on this actual measurement value,
Even if the sugar content is calculated using the model formula shown in No. 147, different results will be obtained.

In order to perform measurements while minimizing the effects of machine differences, installation differences, and changes over time between measuring devices, the measuring devices are calibrated (adjusted) using the diffuse reflector according to the present invention. This calibration will be explained below.

FIG. 7 is a calibration graph for calibrating the measured value of reflectance using a diffuse reflection plate. The vertical axis is the measured value of reflectance;
The horizontal axis represents the calibrated reflectance output value (calibration value). LL
, LO indicates a calibration graph. The calibration graph is a graph for deriving the output value (calibration value) of anti-weight capacity from the actual measurement value.

The calibration value is a reflectance value that removes as much as possible the effects of machine differences between measuring devices, installation differences, and changes over time.If you estimate the sugar content based on this calibration value, you can calculate a more accurate sugar content value. .

If the actual measurement value is not affected by the above-mentioned machine difference or the like, the actual measurement value may be used as is for calculating the sugar content. In other words, the calibration graph at this time becomes the straight line LL in FIG. According to the straight line LL, the calibration value on the horizontal axis is the same as the measured value on the vertical axis.

On the other hand, when considering the influence of machine differences, etc., it is necessary to create a calibration graph specific to the measuring device. In this case, reflectance is measured using a diffuse reflector, data for calibration is obtained, and a graph for calibration is created.

An example of calibrating the peach sugar content measuring device shown in FIG. 4.5 will be described below using a diffuse reflector whose reflectance is close to 100%.

A diffuse reflector with a reflectance close to 100% can be made using a commercially available transmission type filter (including glass plates and plastic plates) with a transmittance of 100%, and a diffuse reflector plate with a diffuse reflectance as explained in Figure 1. Create in layers.

This diffuse reflection plate 1 is fixed to a base 6 as shown in FIG. 2, and the base 6 is further attached to a mounting tool 10 as shown in FIG. 3. Then, as explained in FIG. 4, it is inserted into the hole 29 in the upper part of the housing 21 of the measuring section. Next, the measuring device shown in FIG. 5 is operated to irradiate light 27 from the light source 26 onto the diffuse reflector 1, and measure the reflectance of the diffuse reflector 1 in the same way as measuring a peach. This diffuse reflector has a reflectance of approximately 100.
%, so if there is no error in the measuring device, the actual measured value of reflectance should be 100%. In reality, as mentioned above, there are machine differences, installation differences, and changes over time, so the actual measured value will not be 100%.

For example, assume that the actual measurement value is 102%. At this time, in FIG. 7, a point PO is plotted such that the vertical axis is the actual value 102% and the horizontal axis is the value to be output 100%.

Then, a straight line LO connecting the origin and point PO is used as a calibration graph. From now on, when measuring a peach, based on this calibration graph LO, a calibration value (■) is calculated as v-(100/102)Xu for the actual measured value U of the peach. Perform such a calibration on six bands 81 to B6.
Perform each of the following. The sugar content may be calculated based on the calculated calibration value V. Note that at this time, the same diffuse reflection plate 1 may be used for each band.

In addition, although an example of calibration using a diffuse reflector with almost 100% reflectance in each band has been explained above, the calibration is not limited to this, and calibration can also be performed using a diffuse reflector with an arbitrary reflectance. good. Also, although the explanation has been made assuming that the reflectance of the diffuse reflector is known, if the reflectance of the diffuse reflector is not known, you can measure the actual reflectance of the diffuse reflector using another method and input it as a constant into the device. good.

The above embodiment is an example in which calibration is performed using one diffuse reflection plate. However, using just one diffuse reflection plate is insufficient from the point of view of accurate calibration. This is because the straight line connecting the origin and the point of the measurement result of the diffuse reflector is used as it is as the calibration graph. That is, for example, the calibration graph LO in FIG. 7 has the origin and the measurement point P using the diffuse reflection plate.
However, in reality, the calibration graph is not always a straight line, and if the calibration graph is limited to a straight line, an error will occur due to this. Further, the calibration graph near the measurement point measured using a diffuse reflection plate can be said to be a graph from which more accurate calibration values can be derived, or the error becomes large when the distance from this measurement point is large.

For example, it is known that a peach as a subject exhibits reflectance within a certain range in each band.

In Figure 7, peach as the subject or its band is approximately U, ~U
, the calibration graph L
The calibration value using O is approximately V.

A value in the range of ~V is output. However, since the calibration data was originally taken near 100% reflectance outside of that range, and the calibration graph LO was assumed to be a straight line, the range of u, ~Llb (or V, ~vb) The error in the calibration is large.

Such errors can be reduced by collecting calibration data using multiple diffuse reflectors (diffuse reflector group) each having a variety of reflectances and creating a more accurate calibration graph. I can do it.

An example of creating a calibration graph using a plurality of diffuse reflection plates each having various reflectances will be described below. Here, the reflectance in each band is approximately 1009o, 70o
%, 50%, and 2596, the peach sugar content measuring device was calibrated using four diffuse reflector plates (diffuse reflector group). All of the diffuse reflection plates are similar to those shown in FIG. 1 except that their reflectances are different. Further, in the same manner as described above, the diffuse reflector is attached to the mounting tool 10, inserted into the hole 29 in the upper part of the housing 21, and the measuring device is operated to measure the reflectance of the diffuse reflector. In addition, when using multiple diffuse reflectors, each diffuse reflector is fixed to a base as shown in Figure 2, and during measurement, the base to which the diffuse reflector to be used is fixed is created. Attachment 1 in Figure 3
Use by screwing it into 0.

FIG. 8 is a calibration graph for calibrating the measured value of reflectance created using four diffuse reflection plates. The vertical axis represents the measured reflectance value, and the horizontal axis represents the calibrated reflectance output value (calibration value). LL, Ll to L4 show calibration graphs.

First, it is assumed that the result of measuring the reflectance (actual value) using four diffuse reflection plates with a certain sugar content measuring device is the following value.

■Actual value of a heavy-duty reflector plate with 100% reflectance...102% ■Actual value of a heavy-duty reflector plate with 70% reflectance...72%■5
Measured value of a diffuse reflector with 0% reflectance: 48% Actual value of a diffuse reflector with 25% reflectance: 27% These measured values are the actual reflectance of the diffuse reflector (100%). ,70%
,...) is due to the machine differences mentioned above.

At this time, the following points P1 to P4 are plotted in FIG.

■Point P4 with actual measurement value 102% and calibration value 100% ■Actual measurement value 7
2%, calibration value 70% point P3 ■ Actual value 48%, calibration value 5
0% point P2 ■ Actual value 27%, calibration value 25% point P1 And the origin and point P1, point P1 and point P2, point P2 and point P3
, a straight line L] to L4 connecting points P3 and P4, respectively, is a calibration graph. From now on, when measuring peaches, use these calibration graphs L1 to L4 to find the calibration value V on the horizontal axis relative to the measured value U on the vertical axis. Such calibration is performed for each of the six hunts 81 to B6. The sugar content may be calculated based on the calibration value V obtained as a result. Note that at this time, the same diffuse reflection plate may be used for each band.

Here, in order to simplify the explanation, it will be assumed that a diffuse reflection plate with a reflectance of 100% exhibits a reflectance of 100% in all six bands 81 to B6. Reflectance 70
%, 50%, and 25%. 4 like this
A single diffuse reflector is commonly used for measurement of each band.

To generalize more, let the coordinates of point P1 be PI(vu++) in the measurement in band Bi (i=1 to 6).

That is, suppose that the actual value of the reflectance measured using a diffuse reflector with a reflectance of Vl1% in band Bi is UZ%. Similarly, the coordinates of point P2 are P2 (V12. Ll
12), the coordinates of point P3 are P3(V 13+ u 1
3) Let the coordinates of point P4 be P4 (V14°u +4). At this time, equations representing straight lines L1 to L4 (for each band) connecting each point are as follows. Note that for each hunt, the variable representing the measured value on the vertical axis is Ui (i=1 to 6), and the variable representing the calibration value on the horizontal axis is Vi (i=1 to 6). Also, the actual reflectance v of the diffuse reflector used, (i=1~
6. It is assumed that j=1 to 4) are held within the device as known values.

Straight line L1: [1N - (u 1+/V+ +) ・Vi
--(1) Straight line L
2: LJi-[(u+2-u,+)/(Vi2-Vth)]
(vt-vz)+u1+...(2) Straight line L3: Ui-[(u+1-u1□)/(V13-Vi2)]
(Vi-VB) 10 + 2... (3) Straight line L4: Di - [(u, a-u 13) / (V+ 4-
V+i)] (Vi-v+y)+ u I3...
(4) Since the above equations (1) to (4) exist for each band, there are 24 equations in total. By solving the above equations (1) to (4) for the calibration value V1, 24 equations (5) to (8) can be obtained. When actually measuring a peach, use a certain band Bi to obtain the actual measurement value Ui,
The calibration value Vi may be calculated using the following formulas according to the range of the actual measurement value Ui.

■Formula (5) when 0kuU1≦u+1 ■Formula (6) when u, 1<Ui≦u12■u,2<Ui
When ≦ui3, formula (7)■u, 3<Ui≦u14
Calibration as shown in formula (8) above is performed using six bands 81~
B6, and the sugar content is calculated based on the calibration value Vi obtained for each band. This allows for more accurate sugar content measurement.

Next, the operation of the sugar content measuring device shown in FIG. 5 will be explained in more detail with reference to the flowcharts shown in FIGS. 9 and 10.

FIG. 9 shows a process for obtaining calibration data using a diffuse reflection plate and obtaining a predetermined formula.

First, in step S1, work register j is set to "1". Next, in step S2, the jth diffuse reflection plate is set in the hole 29 of the housing 21 of the measuring section. Here, the first sheet is a diffuse reflector with a reflectance of 25%, the second sheet is a diffuse reflector with a reflectance of 50%, the third sheet is a diffuse reflector with a reflectance of 70%, and the fourth sheet is a diffuse reflector with a reflectance of 100%. It was used as a diffuse reflector.

Next, in step S3, light is irradiated from the light source 26, and the reflectance of the jth diffuse reflection plate in bands 81 to B6 is measured. The actual measured value for each band is in register u+1 (
i-1 to i-6). Further, in step S4, a predetermined constant is stored in v,1 (i-1 to i-6). This is the actual reflectance value in each band of each diffuse reflector,
It is assumed that the value is stored in the ROM 37 as a constant in advance.

Specifically, the values of the six registers y, , (iws1 to 6) are "25" because they are the reflectance of the first diffuse reflector.
, similarly v+2 (i-1 to 6) is "50", V 13
(t-1 to 6) is r70J, V: 4 (i = 1 to 6
) becomes rlooJ. Note that Vll is set as above for convenience of explanation, but in reality, 1 Vll is set for each band.
Since the actual reflectance indicated by different diffuse reflectors is not all the same, it is necessary to measure it in advance using another method.
It is set to . Alternatively, it may be possible to input from the outside.

In step S5, it is determined whether the value of the register j is equal to or greater than "4", that is, whether the measurement of all four diffuse reflection plates has been completed. If it is not finished yet, increment the register j in step S6, return to step S2, and add the next diffuse reflector (reflectance 50%).
Measurement is carried out using a diffuse reflector of 70% and 100% respectively. When the measurement is completed for all four diffuse reflection plates, the process advances to step S7. With the above, point Pj (
The coordinates pj (vl,, J)) of j=1 to 4) were all found. These values are stored in registers V, 1u1□ (i-1 to 6) on RAM36 with battery backup function.
．． j=1 to 4), and will not be erased even if the switch is turned off. The values of these registers are held until the next calibration operation shown in FIG. 9 is performed.

In step S7, each band B] to B is determined based on the measurement results.
6, the above equations (5) to (8) are created. The creation of these equations is the same as the creation of the calibration graphs L1 to L4 in FIG. 8 for each band for the measuring device. For convenience of explanation, formula (5) in band B1 (i-1 to 6) is replaced by formula (
1-1), equation (6) into equation (i-2), equation (7) into equation (i
-3), equation (8) is called equation (1-4). therefore,
The calibration equation (i-j) based on the calibration graph Lj in band Bi is 1=1 to 6. Assuming that j=1 to 4, the following equation is obtained.

Vi-[(VB-V1t+-++)/(lJn-uIw
−1,)] '(Ui−vz+−1))” V:1−1
1...(i-j) Tatami, ixl~6, LIIO=0, ■. =0.

After step S7, the process ends.

As shown in Figure 9, for each hunt, equations (i-1) to (i
-4), the sugar content of the peach is measured using this sugar content measuring device as shown in FIG.

First, in step Sll, measure the peach at 71 Uzing 21.
Set it in the specified position inside. Next, in step 512, light is irradiated from the light source 26, and the reflectance of the peach in bands B1 to B6 is measured. The actual measured value for each hand is stored in register Ui (i=1 to 6).

Next, in step 313, work register l is set to "1".

In step 514, the actually measured reflectance UiO value is determined.

When U1≦u+1, the process proceeds to step S15;
When Ui≦u1□, the process proceeds to step 516;
When ≦u+3, proceed to step S17; LI B<U
When l≦u, 4, the process branches to step S18.

Next, in step S19, the value of register 1 is incremented, and in step S20, it is determined whether the value of register 1 is "7" or more. If the value of register 1 is not "7" or more, it means that processing has not been completed for all bands, and the process returns to step S14 to continue processing for the next band. In step S20, register i
When the value is "7" or more, it means that the calibration values Vi (i=1 to 6) have been obtained for each of the six bands B1 to B6, and the process advances to step S21.

In step S21, quality is determined based on the calibration values Vi (i-1 to i-6). This quality judgment is based on the equity level 1-
A model formula such as that shown in No. 301147 may be used.

In step S22, it is determined whether the processing has been completed for all peaches, and if there are still peaches to be measured, step S22 is performed.
Return to ll. Once the quality measurement of all peaches has been completed, the process ends.

In addition, in the above case, the reflectance is approximately 100%, 70%, and 50%.
, 25%. However, the present invention is not limited to this, and calibration may be performed using a diffuse reflector having an arbitrary reflectance. Also, the actual reflectance of the diffuse reflector (
Although V and I) have been described as known, if the reflectance of the diffuse reflector is not known, the reflectance of the diffuse reflector may be measured by another method and input as a constant into the device. Furthermore, it is not necessary for one diffuse reflector to always have a constant reflectance in each band. For example, with pan l”Bl, the reflectance is 7.
A 0% diffuse reflector may exhibit a reflectance of less than 70% in band B2. In this case, it is necessary to measure the actual reflectance of the diffuse reflector in each band using an appropriate method and set it inside the device.

In the above embodiment, steps S14 to S18 in FIG.
As shown in Figure 2, the formula for calculating the calibration value is selected depending on the range in which the actual measurement value falls. If it fits, the calculation may be performed by fixing the formula used for each band. For example, the reflectance of band B1 can be calculated using the formula (1
-4), and formula (1-3) is used to calculate the reflectance of band B2.
The calculation may be performed by fixing the equation to be calibrated for each band, such as using equation (1-1) for calculating the reflectance of band B3. In this case, unnecessary formulas do not need to be created, and determinations such as those in steps 514 to 318 are also unnecessary.

Furthermore, in the above example, the actual reflectance of the diffuse reflector is known, and a constant (register Vll~
Although the actual reflectance of the diffuse reflector does not need to be known, it is assumed that the reflectance is held (or can be input from the outside) as the value of V61. For example, when calibrating another measuring device, the value of the reflectance of a diffuse reflector measured by one measuring device is stored in register v1. It may be set to This makes it possible to relatively match the characteristics of the measuring device to a certain measuring device.

Also, in the above example, the calculation is performed using the reflectance value, but
Calculation may be performed using the value of a signal obtained by amplifying the output signal of the light receiving element as a value similar to the reflectance.

In this case, the above-mentioned register u11. V+I+U
l.

The value stored in Vi is not the reflectance but a signal value (hereinafter simply referred to as signal value) obtained by amplifying the output signal of the light receiving element.

Table 1 below shows the reference values and the numerical values shown by the subject peach when four diffuse reflection plates F1 to F4 are used.

These values are all signal values obtained by amplifying the output signal of the light receiving element.

Each band in Table 1 B1 to B6 is described in the above-mentioned Japanese Patent Application Laid-open No. 1-301147.
The wavelength range shown in the issue was used. In addition, the diffuse reflection plate F1~
F4 is a commercially available transmittance of 100%.

Four transmission filters of 70%, 50%, and 25% were used, each provided with a metal layer as explained in FIG. 1.

The signal value indicated by peach in a certain band falls within a certain range, as shown in the "Value of Subject" column of this table. Therefore, it may be used for the actual measured values of the band of the calibration graph (ie, formula % formula %) based on the measured values of the diffuse reflector having reference values relatively close to the upper and lower limits of the range. The reference value is a signal value measured using each diffuse reflection plate in one specific sugar content measuring device (referred to as a reference device). For example, using a reference device, in band B1, diffuse reflector F3 is
This means that the signal value at the time of measurement was r877J.

The characteristics of other sugar content measuring devices shall be calibrated so as to be relatively consistent with this reference device. These reference values are stored on the ROM of other sugar content measuring devices other than the reference type.

Then, the actual measured values measured using each diffuse reflection plate and ROM
A calibration equation is created in the same manner as above using the reference value stored above. The formula creation procedure may be similar to that shown in FIG.

Specifically, create the following calibration formula for each band.

Band B1: Equation (1-4) corresponding to the calibration graph L4 is created from the actual measurement value u13 of the third diffuse reflection plate F3 and the actual measurement value 014 of the fourth diffusion reflection plate F4. Here, V13-8
77, VI4-2460.

Band B2: Equation (2-3) corresponding to the calibration graph L3 is created from the actual measurement value u2° of the second diffuse reflection plate F2 and the actual measurement value [2B of the third diffuse reflection plate F3. Here, v2□−3
74, V23-921.

Band B3: Equation (3-3) corresponding to the calibration graph L3 is created from the actual measurement value u3° of the second diffuse reflection plate F2 and the actual measurement value u33 of the third diffusion reflection plate FB. Here, VB2-5
14. V33”1121.

Band B4: Equation (4-2) corresponding to the calibration graph L2 is created from the actual measurement value LI41 of the first diffuse reflection plate F1 and the actual measurement value u4□ of the second diffusion reflection plate F2. Here, ■4□−
m205. It is V4□-679.

Band B5: Equation (5-3) corresponding to the calibration graph L3 is created from the actual measurement value u52 of the second diffuse reflection plate F2 and the actual measurement value u53 of the third diffusion reflection plate F3. Here, Vq2-8
79. It is V53-1450.

Band B6: Equation (6-2) corresponding to the calibration graph L2 is created from the actual measurement value u61 of the first diffuse reflection plate F1 and the actual measurement value u62 of the second diffusion reflection plate F2. Here, V61-4
17. There is v62-989”C.

After creating the above formula, when actually measuring peaches, the actual measured values of each band are applied to the above correspondence formula to calculate a calibration value, and the sugar content is calculated based on the calibration value.

On each of the above-mentioned sides, the process (FIG. 9) for obtaining the calibration equation is performed, for example, when the measuring device is manufactured or shipped. As a result, the measuring device stores a calibration equation unique to that device. Therefore, when actually measuring peaches, it is possible to prevent machine differences from affecting the measurement results. Also, if this is done after the equipment has actually been installed, the effects of installation differences can be prevented as much as possible, and if it is done after a certain period of time, the effects of changes over time can be prevented as much as possible. I can do it.

Note that the diffuse reflection plate according to the present invention can be used not only for calibrating the above-mentioned peach sugar content measuring device, but also for various other purposes. For example, it may be used for sugar content measuring devices other than peaches. In addition, it can be used not only for measuring sugar content but also for calibrating a wide range of measuring devices that perform spectrophotometry.

[Effects of the Invention] As explained above, according to the diffuse reflector according to the present invention, light incident on one surface of a transmission filter is diffusely reflected on the other surface of the filter, and Since the metal layer is provided on the surface, a diffuse reflection plate is provided that is hard to be scratched, is not affected by temperature or humidity, and has extremely little change over time.

In addition, since diffuse reflectors with various reflectances can be easily created, the measurement target can be, for example, a subject whose reflectance is not very high or a subject whose reflectance range varies from band to band. A group of diffuse reflectors having various reflectances is provided so that the measurement device can be calibrated accurately.

[Brief explanation of the drawing]

Figure 1 (A) is a plan view of a diffuse reflection plate according to an embodiment of the present invention, Figure 1 (B) is a side view thereof, and Figure 2 (A) is used for calibration of a peach sugar content measuring device. A plan view of the diffuse reflector and the base to which the diffuse reflector is fixed, FIG. 2 (B) is a side view thereof, and FIG. 3 (A) is a plane view of the mounting tool to which the base to which the diffuse reflector is fixed is attached. Figure 3 (B) is a side view, Figure 4 is a perspective view showing how the peach whose sugar content is to be measured is moving along a line, and Figure 5 is a side view of the peach whose sugar content is to be measured. Fig. 6 is a block diagram of the sugar content measurement device; Fig. 6 is a graph showing differences in the measured reflectance due to machine differences, installation differences, and changes over time; Figure 8 is a calibration graph for calibrating the actual measured value of reflectance created using four diffuse reflectors. FIG. 10 is a flowchart showing the procedure for measuring the sugar content of peaches using a sugar content measuring device. ]... Diffuse reflection plate, 2-channel transmission filter, 5... Metal layer, 6... Base, 1o... Mounting tool, 2]... Measurement unit housing, 22... Conveyor, 23...Challenge (
object), 25... opening, 26... light source, 29.
... hole, 31 ... spectrometer, 32 ... light receiving element, 33 ...
...Amplifier, 34...Input/output (Ilo) interface, 35...Central processing unit (CPU), 36...
・RAM, 37...ROM. 38...External storage device, 39...Pass line. Patent applicant: Mitsui Mining & Mining Co., Ltd. Patent attorney: Tatsuo Ito

Claims (3)

[Claims] (1) A diffuse reflection plate characterized in that a metal layer is provided on the other surface of the transmission filter so that light incident from one surface of the filter is diffusely reflected on the other surface of the filter. (2) A transmission filter that has a substantially flat transmittance for light in a predetermined wavelength range, and a transmission filter that allows light incident on one surface of the transmission filter to be diffusely reflected on the other surface of the transmission filter. and a metal layer provided on the other surface. (3) A diffuse reflector group consisting of a plurality of diffuse reflectors used to calibrate a measuring device having a function of spectrophotometrically measuring reflected light from an object to be measured, wherein the diffuse reflector group has a transmittance of A diffuse reflector group comprising a plurality of diffuse reflectors according to claim 1 or 2 configured using a plurality of transmission filters different from each other.