JP2003130727A - Apparatus and method for measuring intensity of light, photodetector and data processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method and a measuring apparatus wherein the intensity of scattered light and the intensity of direct light can be measured precisely, to provide a measuring method and a measuring apparatus wherein the intensity of direct light can be measured, to provide a measuring apparatus and a measuring method whose portability is high, which are low-cost and whose adjustment and maintenance are not required, and to provide a measuring method and a measuring apparatus whose portability is high, which are low-cost, whose adjustment and maintenance are not required and which can measure the intensity of direct light and the intensity of scattered light precisely. SOLUTION: A plurality of photodetectors (101, 102) as a pair whose detection sensitivities with reference to the scattered light from among irradiation light incident on a prescribed plane are different are installed on the prescribed plane, the intensity difference (Amn) of the scattered light is measured, the intensity (Es) of the scattered light is measured on the basis of the intensity difference, and the intensity of the direct light and the intensity of the scattered light from among the irradiation light are measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light intensity measuring device, a light intensity measuring method, a light detecting device and a data processing device for measuring the light intensity of sunlight or light radiated by an artificial light source. Field, meteorological field, in the field of solar energy use such as solar power generation field, a light intensity measuring device for measuring the ratio of the direct light component and the scattered light component of sunlight or irradiation light incident on an arbitrary surface, The present invention relates to a light intensity measuring method, a light detecting device, and a data processing device.

[0002]

2. Description of the Related Art The measurement of solar radiation intensity is an important measurement in the field of utilizing solar energy. The luminous flux of sunlight reaching the ground has a direct light component and a scattered light component, which are called direct solar radiation and scattered solar radiation, respectively. In addition, the total of direct solar radiation and scattered solar radiation is called total solar radiation.

Since direct solar radiation and scattered solar radiation vary with local and atmospheric conditions, measuring direct solar radiation and scattered solar radiation, respectively, is important for the utilization of solar energy.

In order to measure direct solar radiation and scattered solar radiation,
Any two of total solar radiation, direct solar radiation and scattered solar radiation may be measured. In other words, either direct solar radiation or diffuse solar radiation must be measured.

As a device for measuring total solar radiation, a global pyranometer is most widely used.

[0006] As a device for measuring direct solar radiation, a direct pyranometer for measuring while tracking the sun is generally used.

Various types of devices are used as devices for measuring scattered solar radiation. For example, based on a pyranometer, scattered solar radiation is measured by blocking direct solar radiation with a shielding band or a shielding ball. Kazuo Shibata and Zenbei Uchijima, “Distribution and measurement of solar energy” (published by the Academic Society Publishing Center), p48, describes a diffuse pyranometer which is an example using a shielding band.

Further, US Pat. No. 4,609,288 discloses a method for measuring direct solar radiation and scattered solar radiation by separating solar radiation into x, y and z components by three pairs of solar cells. . Also, in WO 99/13359,
By using a plurality of optical sensors, a shielding pattern is provided for this optical sensor so that at least one optical sensor is always exposed to direct light and at least one other optical sensor is always shielded from direct light. And a method for simultaneously measuring scattered solar radiation are disclosed.

However, in order to measure direct solar radiation,
As explained above, it is basically necessary to track the sun. This tracking device is very expensive. Moreover, since it requires precise adjustment, it is not suitable for carrying.

On the other hand, to measure scattered solar radiation, for example,
There is a method using a pyranometer and a shielding ball. In this case, it is necessary to track the sun in order to adjust the direction of the shield ball. This tracking device is very expensive as in the case of measuring direct solar radiation.

Another method for measuring scattered solar radiation is, for example, a method using a pyranometer and a shielding band. This method does not require an expensive tracking device, but it requires the elevation angle of the shielding band to be adjusted regularly and the device to be adjusted frequently. Here, if the shielding band is of a rotary type, frequent adjustment of the device is unnecessary, but since a rotating mechanism is required to rotate the shielding band, the system is also expensive and large-scale.

As another method for measuring scattered solar radiation, there is a method disclosed in the above-mentioned US Pat. No. 4,609,288, but this method requires no driving part but requires a large-scale apparatus and is compact. There is a problem that it is difficult.

The method using the above-mentioned shielding band, US Pat. No. 4,609,288 and WO 99/13.
In the methods disclosed in No. 359, only the scattered solar radiation in a part of the sky is measured. In addition, it is assumed that the scattered solar radiation at unmeasured angles is uniform. Therefore, there is a problem that the measurement error is large.

In general, the scattered solar radiation is not uniform with respect to the angle, and particularly when the reflected light from the ground or an object enters the surface to be measured, the scattered solar radiation significantly differs depending on the angle. Therefore, it is not generally applicable to assume that the scattered solar radiation at the non-measurement angles is uniform as described above, and the measurement error becomes large.

[0015]

When utilizing solar energy, it is necessary to accurately measure direct solar radiation and scattered solar radiation in various places. However, in the measuring device using the conventional measuring method described above, 1) the device is too large,
There were problems such as 2) too heavy, 3) too high cost, 4) frequent adjustment and maintenance required, and 5) large error.

The object of the present invention is to solve the above-mentioned problems of the prior art individually or collectively, and provides a measuring method and a measuring apparatus capable of accurately measuring the scattered light intensity. That is. Another object of the present invention is to provide a measuring method and a measuring device capable of measuring the direct light intensity. Still another object of the present invention is to provide a measuring device and a measuring method thereof which have high portability, low cost, and no adjustment or maintenance required.

[0017]

An optical intensity measuring method according to an embodiment of the present invention for achieving the above object has the following constitution. That is, a method of measuring the light intensity of irradiation light, which has a plurality of photodetector reference planes which are installed on a predetermined surface and are parallel to each other, and which have different detection sensitivities to scattered light. It is characterized by comprising a light intensity measuring step of measuring and a scattered light intensity calculating step of calculating scattered light intensity (Es) based on outputs of a plurality of photodetectors having different detection sensitivities to the scattered light.

Here, for example, the scattered light intensity calculation step includes a step of calculating an output difference from outputs of the plurality of photodetectors, and the scattered light intensity can be calculated using the output difference. preferable.

Here, for example, the scattered light intensity calculating step includes a step of calculating a normalized output difference based on the outputs of the plurality of photodetectors, and the scattered light intensity is calculated using the normalized output difference. It is preferable to calculate the strength.

Here, for example, the plurality of photodetectors are
It is preferable that the detection sensitivities according to the incident angle of the irradiation light are different from each other.

Here, for example, the plurality of photodetectors are
It is preferable to have a uniform sensitivity to the azimuth angle of the irradiation light.

Here, for example, the spectral sensitivities of the plurality of photodetectors are preferably controlled so that the mismatch coefficient indicating the deviation between the spectral sensitivities is 0.98 or more and 1.02 or less. .

Here, for example, the incident angle of the photodetector is 0.
The incident angle of the photodetector is 0 °, where the sensitivity is 1
The deviation from the cosine law of the relative sensitivity at an incident angle of 60 ° with respect to the sensitivity of is preferably 0.06 or more as a difference between the deviations occurring in each photodetector when using the plurality of photodetectors. .

Here, for example, the scattered light intensity (Es)
It is preferable to calculate the direct light intensity (Ed) of the irradiation light incident on the predetermined surface based on the above.

An optical intensity measuring device according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a light intensity measuring device for measuring the light intensity of the irradiation light, which is installed on a predetermined surface, having light detection reference planes parallel to each other, a plurality of photodetectors with different detection sensitivity to scattered light, Scattered light intensity calculation means for measuring scattered light intensity (Es) based on outputs of a plurality of photodetectors having different detection sensitivities to the scattered light.

Here, for example, the plurality of photodetectors are
It is preferable that the detection sensitivities according to the incident angle of the irradiation light are different from each other.

Here, for example, the plurality of photodetectors are
It is preferable to have a uniform sensitivity to the azimuth angle of the irradiation light.

Here, for example, the spectral sensitivities of the plurality of photodetectors are preferably controlled so that the mismatch coefficient indicating the deviation between the spectral sensitivities is 0.98 or more and 1.02 or less. .

Here, for example, the incident angle of the photodetector is 0.
The incident angle of the photodetector is 0 °, where the sensitivity at 1 is 1.
The deviation from the cosine law of the relative sensitivity at an incident angle of 60 ° with respect to the sensitivity of is preferably 0.06 or more as a difference between the deviations occurring in each photodetector when using the plurality of photodetectors. .

Here, for example, it is preferable to calculate the direct light intensity of the irradiation light incident on the predetermined surface based on the scattered light intensity.

Here, for example, the photodetector has a photoelectric conversion element, and the photodetection for the scattered light is performed by the surface texture of the surface where the photoelectric conversion element receives the irradiation light and / or the back surface thereof. It is preferable to change the detection sensitivity of the vessel.

Here, for example, the photodetector has a photoelectric conversion element and a translucent member that covers the photoelectric conversion element, and the translucent member detects the scattered light by the photodetector. It is preferable to change the sensitivity.

Here, for example, it is preferable that the photodetector has a photoelectric conversion element and a filter, and the detection sensitivity of the photodetector with respect to the scattered light is changed by the filter.

Here, for example, it is preferable that the photodetector has a photoelectric conversion element and a mesh, and the detection sensitivity of the photodetector with respect to the scattered light is changed by the mesh.

Here, for example, the photodetector has a photoelectric conversion element and a light-scattering light-transmitting member, and the light-scattering light-transmitting member changes the detection sensitivity of the photodetector with respect to the scattered light. Preferably.

Here, for example, it is preferable that the portable device be portable.

A program according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a program for realizing the measuring method for measuring the light intensity described above.

A computer-readable storage medium according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a computer-readable storage medium storing a measurement processing program for controlling the measurement processing of the light intensity of the irradiation light, wherein the measurement processing program has light detection surfaces that are parallel to each other and are installed on a predetermined surface. Then, using a plurality of photodetectors with different detection sensitivity for scattered light, the light intensity measurement step of measuring the irradiation light, and the scattered light intensity based on the output of the plurality of photodetectors with different detection sensitivity for the scattered light. And a scattered light intensity calculating step of calculating (Es).

A photodetector according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a photodetector for measuring the light intensity of irradiation light, having a plurality of photodetectors installed on a predetermined surface and having parallel photodetection surfaces and different detection sensitivities to scattered light. Characterize.

A data processing apparatus according to an embodiment of the present invention for achieving the above object has the following configuration. That is, a data processing device for processing the measured value of the light intensity of the irradiation light, wherein the receiving means receives outputs from a plurality of photodetectors having different detection sensitivities to scattered light, and the plurality of receiving means received by the receiving means. Scattered light intensity calculation means for calculating scattered light intensity (Es) based on the output from the photodetector,
It is characterized by having.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION A light intensity measuring method and a light intensity measuring apparatus as an example of an embodiment according to the present invention will be described below with reference to the drawings.

(Light intensity measuring device: FIG. 1) In the embodiment of the present invention, for example, the configuration of the light intensity measuring device shown in the schematic view of FIG. 1 can be used.

In FIG. 1, the light intensity measuring device comprises a light intensity detecting section 100 and a data processing section 150.

In the light intensity detector 100, 101 is
The first photodetector 102 is a second photodetector 103
Is a photoelectric conversion element of the first photodetector, 104 is a photoelectric conversion element of the second photodetector, 105 is a surface member of the first photodetector, and 106 is of the second photodetector. It is a surface member. 107 is the case of the light intensity measuring device, 108, 10
9 is an output terminal of the first photodetector, and 110 and 111 are
It is an output terminal of the second photodetector.

In the data processing unit 150, 11
Reference numerals 8 and 119 are input terminals for inputting the output of the first photodetector, and 120 and 121 are input terminals for inputting the output of the output of the second photodetector. 108 and 118, 109 and 1
19, 110 and 120, 111 and 121 are connected by a cable (not shown). The data processing unit 150 is composed of a CPU, a RAM, a ROM, an input unit, a display unit, and the like (not shown). The CPU controls the calculation processing of scattered light intensity, direct light intensity, etc., which will be described later, based on the processing program stored in the ROM. The RAM functions as the main memory and work area of the CPU. Further, in the RAM, measured values measured by the light intensity detection unit 100 and various measured values previously measured (for example, Xm (θ), Xm (0), Xn).
(θ), Xn (0), etc., which will be described later in detail) and the like are stored. The input unit inputs data and the like, and the display unit displays the calculation processing result.

The light intensity measuring device is not limited to the configuration in which the light intensity detecting section 100 and the data processing section 150 are independent as described above, and the light intensity detecting section 100 includes the data processing section 150. It may have an integrated structure.

(Measuring Method of Scattered Light Intensity) In the light intensity measuring method of the present invention, the total irradiated light intensity and the scattered light intensity are measured in order to derive the direct light intensity and scattered light intensity of the irradiated light. The present invention is characterized by the method of measuring the scattered light intensity.

The method for measuring the scattered light intensity in the light intensity measuring method of the present invention will be described in detail below.

First, if the output P of the photodetector for detecting the intensity of the irradiation light is divided into the output Pd by the direct light and the output Ps by the scattered light, the following equation (1) is generally established.

P = Pd + Ps (1) Further, the sensitivity X of the photodetector can be expressed by the following equation (2) from the intensity E of the irradiation light and the output P of the photodetector.

X = P / E (2) Next, the direct light intensity of the irradiation light incident at the incident angle θ on the arbitrary surface on which a plurality of photodetectors of the present invention are installed is Ed. , The scattered light intensity is Es, the sensitivities of the m-th and n-th photodetectors of the present invention to the direct light at the incident angle θ are Xm (θ) and Xn (θ), and the sensitivities to the scattered light are XmS and Xn, respectively.
Assuming S, the outputs of both photodetectors under a certain irradiation light are expressed by the following equations, respectively.

Pm = Xm (θ) · Ed · cos θ + XmS · Es (3) Pn = Xn (θ) · Ed · cos θ + XnS · Es (4) The normalized output difference ΔPmn of the container is defined by the following equation (5).

ΔPmn = Pm / Xm (0) −Pn / Xn (0) (5) Here, Xm (0) and Xn (0) are the two lights at an incident angle of 0 °. It is the direct light sensitivity of the detector, and each photodetector output P
The reason why m and Pn are divided by Xm (0) and Xn (0) is to normalize the output difference of both photodetectors to facilitate detection.

Further, the difference between the incident angle sensitivities of the two photodetectors is defined as Cmn (θ) by the following equation (6), and Cmn (θ) = Xm (θ) / Xm (0) -Xn ( θ) / Xn (0) (6) The difference between the scattered light sensitivities of both photodetectors is defined as Amn, and is defined by the following equation (7).

Amn = XmS / Xm (0) −XnS / Xn (0) (7) Next, the expressions (3) and (4) are substituted into the expression (5) to obtain the expression (6 ) And (7) are used, Cmn (θ) and Amn are used to express the equation (5) as the following equation (8).

ΔPmn = Cmn (θ) · Ed · cos θ + Amn · Es (8) Here, if the total irradiation light intensity of the installation surface measured by both photodetectors is Et, then Ed = ( Et-Es) / cos θ (9) Therefore, by substituting the equation (9) into the equation (8) and solving for Es, the following equation (10) is obtained.

Es = (ΔPmn−Cmn (θ) · Et) / (Amn−Cmn (θ)) ·· (10) The present inventor has described the above in various scattered light states under the condition that θ is constant. The scattered light sensitivity difference Amn could be experimentally obtained by obtaining Es and ΔPmn and correlating them. At this time, the scattered light intensity Es was measured by a conventional method of comparing a total pyranometer and a scattered pyranometer. Also,
Xm (θ), Xm (0), and Xn (θ) are measured in advance by measuring the incident angle dependence of the sensitivities of the photodetectors using substantially parallel light such as a pseudo sunlight light source. , Xn (0) have been measured. Using the result, the incident angle sensitivity difference Cm
n (θ) was calculated.

In this way, the present inventor
And Cmn (θ) are known, the incident angle θ of the direct light of the irradiation light is measured or calculated, and the standardized output difference ΔPmn between the two photodetectors is measured to obtain the desired irradiation light. It has been found that the scattered light intensity Es can be obtained. Amn may be in the form of a function of Es.

Further, when Amn and Cmn (θ) are equal, Es cannot be clearly obtained by the equation (10). In such a case, the incident angle θ of the direct light should be changed. Then, the measurement may be performed again under the condition that the following formula (11) is satisfied.

Cmn (θ) ≠ Amn (11) When the difference between the values of Xm (0) and Xn (0) is small,
The following formulas (5) ′, (6) ′, and (7) ′ may be used instead of the above formulas (5), (6), and (7). In this case, ΔPmn is called the output difference.

ΔPmn = Pm−Pn (5) ′ Cmn (θ) = Xm (θ) −Xn (θ) (6) ′ Amn = XmS−XnS (7) 'Naturally, the total irradiation light intensity E is obtained by the light intensity measuring device of the present invention.
Since t is also measured, from the measured Es and Et values,
The direct light intensity Ed can be easily obtained by the equation (9).

To measure the total irradiation light intensity Et, for example, if the sensitivities of the m-th and n-th photodetectors of the present invention with respect to the total irradiation light intensity are Xmt and Xnt, they are measured in advance, It can be obtained by any of the following equations (12) to (14). From equation (12) to equation (1
Which of 4) is used may be selected depending on the type of photodetector, one having high accuracy with respect to the total irradiation light intensity, or averaging the results of each photodetector.

Et = Pm / Xmt (12) Et = Pn / Xnt (13) Et = Average (Pm / Xmt, Pn / Xnt) (14) In the light intensity measuring method of the present invention, when the respective values of the scattered light sensitivities XmS and XnS are independently obtained in advance by calculation or measurement, the scattered light intensity Es and the direct light are calculated by the following procedure. The intensity Ed can be obtained.

That is, first, Pm and Pn are measured, and θ
Is calculated or calculated, and Xm corresponding to θ
The values of (θ) and Xn (θ) are calculated.

Next, the equation (9) is substituted into the above equations (3) and (4) to form the following equations (3) 'and (4)'.

Pm = Xm (θ) · Et + (XmS−Et · Xm (θ)) · Es ·· (3) ′ Pn = Xn (θ) · Et + (XnS−Et · Xn (θ)) · Es · -(4) 'Next, Et is obtained from the above-mentioned equation (12), and the equation (3)' is obtained.
The value of Es can be obtained by substituting for Es and solving for Es. This value is Esm. In addition, the above equation (1
The value of Es can be found by finding Et from 3), substituting it in equation (4) ′, and solving for Es. This value is Esn.

If Esm = Esn, this value is adopted as Es. If Esm ≠ Esn, the average value of Esm and Esn is adopted as Es,
Alternatively, one of Esm and Esn that is considered to have a small error is adopted as Es. Next, in equation (9), Et
And Ed are substituted to obtain Ed.

(Calculation Method of Scattered Light Intensity Es and Direct Light Intensity Ed: FIG. 9) In the flowchart shown in FIG. 9, the scattered light intensity Es and the direct light intensity are calculated based on the method of measuring the scattered light intensity described above. An example of a method of calculating Ed will be shown. The processing of this calculation method is executed under the control of the CPU based on the processing program stored in the ROM of the data processing unit 150 of the light intensity measuring device.

In step S010 in FIG. 9, in advance,
Xm (θ), Xn (θ), A required for calculating the scattered light intensity Es
mn is measured and stored in the data processing unit. Here, the range of the incident angle θ is 0 ≦ θ ≦ 90 °, and Xm (θ) and Xn (θ) are measured at arbitrary angle steps. The angle step is at least 30 ° or less, preferably 15 °
The following are desirable: Further, the value of θ = 0, Xm (0), Xn
(0) is essential. Amn is experimentally obtained as described above.

If the scattered light sensitivities XmS and XnS can be obtained independently, it is desirable to obtain them in advance.

Next, in step S110, the value of the incident angle θ of the direct light of the irradiation light on the photodetector is measured or obtained by calculation as described later in the first embodiment, and the data processing unit To enter.

Next, in step S120, the difference Cmn (θ) between the incident angle sensitivities of the m-th and n-th photodetectors is calculated by the above equation (6) (Cmn (θ) = Xm (θ) / Xm (0) ) -Xn
(θ) / Xn (0)) or equation (6) ′. If the values of Xm (θ) and Xn (θ) do not exist in the previously measured data, Xm of the neighboring angular steps
The values of (θ) and Xn (θ) are interpolated or extrapolated by linear or curved approximation.

Next, in step S130, the value of Cmn (θ) obtained in step 120 is compared with the value of Amn previously acquired in step S010, and the above equation (1
1) If (Cmn (θ) ≠ Amn) is established, the process proceeds to the next step S150. If not, step S1
Proceed to 40.

In step S140, the incident angle θ of the direct light is changed by changing the installation surface of the both photodetectors or changing the measurement time. After that, the process returns to step S110 again.

Next, in step S150, the output values Pm and P measured by the mth and nth photodetectors are measured.
n is received and input (Pm and Pn are expressed by equation (3),
(4)).

Next, in step S160, the normalized output difference ΔPmn between the m-th and n-th photodetectors defined by the equation (5) is calculated from the output difference between the measured output values Pm and Pn of the photodetector. (ΔPmn = Pm / Xm (0) −Pn / X
n (0)) or the output difference ΔP defined by equation (5) ′
Calculate mn. Next, in step S170, the total irradiation light intensity Et of the installation surface is calculated from the measured output value Pm or Pn of the photodetector using any one of the above equations (12) to (14).

Next, in step S180, ΔPmn and Cmn (θ), Amn, E obtained in the previous step are calculated.
Using t, the above equation (10) (Es = (ΔPmn−C
The scattered light intensity Es is calculated using mn (θ) · Et) / (Amn−Cmn (θ))).

Next, in step S190, the direct light intensity Ed is calculated using the above equation (9) (Ed = (Et-Es) / cos θ).

Next, in step S200, θ, Pm, Pn, Et, Es, E acquired in the above steps are
Store d in the storage means.

In the above description, the memory of the data processing unit 150 stores in the memory Xm (θ), Xm necessary for calculating the scattered light intensity Es.
Although n (θ), Xm (0), Xn (0), Amn, θ and the like have been described in advance as examples, these values may be measured and input. .

Further, when the respective values of the scattered light sensitivities XmS and XnS are obtained in advance, the above-mentioned step S1 is performed.
20, instead of obtaining the difference in incident angle sensitivity from Cmn (θ), the values of Xm (θ) and Xn (θ) corresponding to θ are obtained.
The above steps S130, S140, and S160 are deleted, and the above equation (1
Instead of using 0), the above equations (3) ′ and (4) ′ are used to calculate the scattered light intensity Es, and the processing can be performed in the same manner as the above-described steps.

(Conditions for selecting a plurality of photodetectors) In the light intensity measuring apparatus of the present invention, it is important that the plurality of photodetectors have different sensitivity changes with respect to the incident angle of irradiation light. For example, according to the representative values used for the m-th photodetector and the n-th photodetector described above, since the scattered light sensitivities of both photodetectors are different, the following formula (15) may be satisfied. Amn> 0 ... (15) More preferably, it is desirable to satisfy the following expression (16) regardless of the incident angle θ.

Cmn (θ) ≧ 0 (16) Hereinafter, this selection condition will be described in detail.

First, the photodetector output Ps by the scattered light
Is the luminous flux of the scattered light incident on the arbitrary surface at a unit solid angle of the incident angle θ and the azimuth angle φ of Es (θ, φ), and the sensitivity of the photodetector to the direct light of the incident angle θ of X (θ). Then, it is represented by the following equation (17).

Ps = ∫X (θ) Es (θ, φ) dω (17) Here, ω is a solid angle, and integration is performed for the upper hemisphere. Further, it is desirable that the photodetector has a uniform sensitivity to the azimuth φ. Since the photodetector has a uniform sensitivity to the azimuth angle φ, the scattered light flux Es (θ, φ)
However, the scattered light intensity could be accurately obtained even when the distribution was nonuniform with respect to the azimuth angle φ.

On the other hand, the scattered light intensity Es is calculated by the following equation (1)
Represented by 8).

Es = ∫Es (θ, φ) dω (18) Therefore, the scattered light sensitivities XmS and XnS of both photodetectors are obtained.
Can be expressed by the following equation.

XmS = ∫Xm (θ) Es (θ, φ) dω / Es ・ ・ ・ (19) XnS = ∫Xn (θ) Es (θ, φ) dω / Es ・ ・ ・ ・ ・ (20 ) Next, by substituting the equations (19) and (20) into the equation (7) representing the scattered light sensitivity difference Amn, the incident angle sensitivity difference Cmn (θ) defined by the equation (6) is used. For example, the following equation (2
1) is obtained.

Amn = ∫Cmn (θ) Es (θ, φ) dω / Es (21) Here, when the scattered light intensity Es of irradiation light is obtained by the method of the present invention described above, It is necessary that the two photodetectors have different sensitivities to scattered light, and the above-mentioned formula (15) must be established.

Therefore, it is necessary that the following expression (22) is established from the expressions (15) and (21).

∫Cmn (θ) Es (θ, φ) dω> 0 (22) However, in general, the luminous flux Es (θ, φ) of scattered light is
It cannot be expressed by a simple function of θ or φ. For example, in the case of scattered light of sunlight on the ground, not only scattering by the atmosphere but also scattering from clouds, scattering from the ground, scattering from buildings, etc., the luminous flux Es (θ, φ) of scattered light is The distribution is complex and constantly changing.

Therefore, in the present invention, it is desirable to satisfy the expression (22) regardless of the distribution of the scattered light flux. For that purpose, the difference Cmn of the incident angle sensitivities is irrespective of the incident angle θ by an appropriate combination of photodetectors.
It is sufficient that (θ) satisfies the expression (16).

That is, the incident angle sensitivity difference Cmn (θ) is
If a pair of photodetectors having a sensitivity that is positive is used regardless of the value of the incident angle θ except θ = 0 °, the formula (15) is satisfied regardless of the luminous flux of the scattered light. Can have different sensitivities to. When θ = 0 °, Cmn (0) = 0 as is apparent from the equation (6).

In other words, in other words, the condition of the expression (16) indicates that the relative sensitivity of the incident angle θ to the sensitivity of the incident angle θ = 0 ° is always higher in one photodetector than in the other photodetector. . It is desirable to use a plurality of photodetector pairs that satisfy such conditions.

Further, in order to calculate the scattered light intensity Es by measuring the normalized output difference ΔPmn of the photodetector from the equation (10), the larger the scattered light sensitivity difference Amn is, the more accurate the Es becomes. Is improved. In order to increase the value of Amn, from Expression (21), the difference Cmn (θ) in the incident angle sensitivity of the photodetector must be large. Therefore, it is desirable to use a plurality of photodetector pairs having a large Cmn (θ).

Here, as a result of experiments on various photodetectors having different incident angle sensitivities, the present inventor found that the magnitude of Cmn (θ) is directly expressed by the value of Cmn (60 °). It was This is the result of the experiment, Cmn (θ) / cos
This is because the value of (θ) often changes monotonically with respect to the incident angle θ.

That is, assuming that the photoelectric conversion portion of the photodetector has a flat shape and is in an ideal state where there is no reflection, absorption, or scattering on the light-incident side, direct light with an incident angle θ of the photodetector is obtained. The sensitivity change follows the following equation (23). Equation (23) will be called the cosine law.

X (θ) = X (0) · cos (θ) (23) However, the actual photodetector has a deviation from this cosine law. Therefore, this shift is expressed as F (θ) and expressed as in Expression (24).

X (θ) = X (0) · cos (θ) · F (θ) (24) By applying the equation (24) to the m-th and n-th photodetectors, Substituting into equation (6), the difference of deviation from the cosine law is Fm
If n (θ) is defined as Fmn (θ) = Fm (θ) −Fn (θ) (25), the formula (6) can be expressed as the following formula (26). .

Cmn (θ) = cos (θ) · Fmn (θ) (26) From Expression (26), the magnitude of the incident angle sensitivity difference Cmn (θ) is
The difference from the cosine law can be attributed to the difference Fmn (θ). F (θ) cannot be represented by a simple function, but as a result of experiments, it often changed monotonically with respect to θ.
Further, if θ is too large, the measurement error of X (θ) becomes large, and if θ is too small, the value of F (θ) is small and detection is difficult. Therefore, the magnitude of Fmn (θ) is Fmn (60 °). It was found that it is preferable to judge by the value of).

The present inventor, as shown in Example 2,
As a result of examining the error between the value of mn (60 °) and the obtained scattered light intensity Es, in order to obtain the scattered light sensitivity difference Amn that is large enough to obtain the scattered light intensity Es, at least Fmn ( It was found that it is desirable that 60 °) ≧ 0.06 (27).

(Light Reference Surface of Photodetector) In the light intensity measuring method and the light intensity measuring apparatus of the present invention, it is necessary that the light reference planes of the plurality of photodetectors are parallel to each other.
Here, the light reference plane of the photodetector is a plane that serves as a reference when defining the incident angle of light on the photodetector. For example, in the case of a photodetector having a planar light receiving element, the light receiving plane serves as a light reference plane. In the case of a photodetector having a non-planar light receiving element, for example, a plane perpendicular to the direction having the maximum light receiving sensitivity is the light reference plane.

Since the light reference planes of the plurality of photodetectors are parallel to each other, the incident angles (θ) of the light with respect to the plurality of photodetectors are the same between the photodetectors. It makes it easier to compare the outputs of the detectors. Further, it is possible to measure the scattered light intensity and the direct light intensity by the above-mentioned method from the difference in the detection sensitivity of each photodetector to the scattered light.

Further, using the light intensity measuring method of the present invention,
When measuring the light intensity incident on a predetermined surface, it is necessary to install the light reference plane parallel to the predetermined surface when the light intensity measuring device of the present invention is installed on the predetermined surface.

(Spectral Sensitivity of Photodetector) Sensitivity X of Photodetector
Is expressed as a function of wavelength λ, where E (λ) is the spectral intensity of the irradiation light and Q (λ) is the spectral sensitivity of the photodetector.
It is expressed by the following formula.

X = ∫E (λ) Q (λ) dλ / ∫E (λ) dλ (28) Here, the spectral intensity of the irradiation light is divided into the direct achievement amount and the scattering component, and If Ed (λ) and Es (λ) are satisfied, then E (λ) = Ed (λ) + Es (λ) (29) The sensitivity Xs is represented by the following formula (30).

Xs = ∫Es (λ) Q (λ) dλ / ∫Es (λ) dλ ·· (30) The photodetector used in the light intensity measuring device of the present invention has a higher scattered light sensitivity Xs. Since the scattered light sensitivity difference Amn can be made large, from the formula (30), it is preferable to use one having a large spectral sensitivity Q (λ) at a large wavelength λ of the scattered light spectrum Es (λ) of the irradiation light.

In the photodetector used in the present invention, when measuring the incident angle dependence X (θ) of the above-mentioned sensitivity, it is desirable that the scattered light is small and the irradiation light is substantially parallel. Therefore, it is desirable to measure in a state where the scattered light of sunlight is blocked and only the direct light reaches, or it is preferable to use an artificial light source that generates little parallel scattered irradiation light. Therefore, if the spectrum of the irradiation light when measuring X (θ) is Ec (λ), then E
c (λ) is close to Ed (λ) and is different from the spectrum E (λ) of the irradiation light to be actually measured.

Therefore, in the case of selecting the m-th and n-th photodetectors used in the present invention, if the spectral sensitivities of the photodetectors are Qm (λ) and Qn (λ), the following equation is obtained. The mismatch coefficient Mmnc defined in (31) is
It is preferably 0.98 or more and 1.02 or less. Mmnc = ∫Ec (λ) Qm (λ) dλ / ∫E (λ) Qm (λ) dλ × ∫E (λ) Qn (λ) dλ / ∫Ec (λ) Qn (λ) dλ ... (31) In the case of measurement of sunlight, the spectrum of sunlight changes every moment. Therefore, when the sunlight spectrum at a certain time point is Et (λ) and the ideal sunlight spectrum is Eo (λ), the mismatch coefficient Mmnt defined by the following equation (32) is similar to the above. 0.98 or more 1.02
The following is desirable.

Mmnt = ∫Eo (λ) Qm (λ) dλ / ∫Et (λ) Qm (λ) dλ × ∫Et (λ) Qn (λ) dλ / ∫Eo (λ) Qn (λ) dλ ... .. (32) As an ideal sunlight spectrum of Eo (λ), for example, JIS C 8911 or IEC 60904-
The AM1.5 reference solar spectrum described in No. 3 is mentioned.

By selecting a photodetector having a spectral sensitivity that satisfies the above mismatch coefficient conditions, the measurement error of the irradiation light intensity due to the difference in the spectral sensitivity of the photodetector and the difference in the spectrum of the irradiation light can be eliminated. Can be made smaller.

If the mismatch coefficient is satisfied, it can be said that the spectral sensitivities of the selected photodetectors are close to each other. Also, the spectral sensitivity of the photodetector paired is
Even if the absolute values are different, if the relative value with respect to the wavelength, that is, the shape of the spectral sensitivity spectrum is approximate, the condition of the mismatch coefficient can be satisfied.

(Photoelectric conversion element of photodetector) As the type of photoelectric conversion element of the photodetector used in the present invention, the following are preferably used.

For example, various semiconductor junctions such as a pn junction, a pin junction, and a MIS type junction, a thermocouple, a thermoelectric stack, and the like can be used. Semiconductor materials used for various semiconductor junctions include crystalline, polycrystalline, microcrystalline, and amorphous materials, and substances include Si, SiC, and SiG.
Group IV or group IV compounds such as e, C, Ge, GaAs,
III-V group compounds such as AlGaAs, InP, InSb,
II such as ZnSe, ZnO, CdS, CdTe, Cu ₂ S, etc.
-VI _compound, CuInSe _2, CuInS 2, etc. I-I
Examples thereof include II-VI group ₂ compounds, organic semiconductors, and the like, or mixtures of the above compounds.

The photoelectric conversion element used in the present invention preferably has little temperature dependence. If the temperature dependence cannot be ignored, either adjust the temperature of the photoelectric conversion element to a constant temperature or measure the temperature of the photoelectric conversion element and correct the measurement result with the temperature coefficient measured in advance. Is desirable.

The incident angle sensitivity of the photodetector can be changed depending on whether the light incident side surface or the back surface of the photoelectric conversion element is smooth or rough. The rough surface can suppress interface reflection on the front surface or the back surface of the photoelectric conversion element, and can improve the scattered light sensitivity.

However, the influence of the back surface is proportional to the amount of light reflected from the back surface and is less than that of the front surface side. The scattered light sensitivity difference Amn can be increased by combining a photodetector having a photoelectric conversion element having a high scattered light sensitivity with a photodetector photodetector having a photoelectric conversion element having a low scattered light sensitivity.

It is desirable that the photoelectric conversion element has stable characteristics over time. At least light resistance, preferably, so that the spectral sensitivity does not change over time,
Those having weather resistance or those subjected to a stabilization treatment are desirable. Further, it is desirable to use one having mechanical strength that is unlikely to be deformed or damaged. In order to reinforce the mechanical strength, a support material may be used or it may be enclosed in a package.

(Surface member of photodetector) The surface member of the photodetector used in the present invention is an important member which greatly affects the incident angle sensitivity. By selecting the surface member, the value of the deviation F (θ) from the cosine law of the incident angle sensitivity can be changed.

By increasing the value of F (θ), the scattered light sensitivity of the photodetector can be increased.
By reducing the value of (θ), it is possible to reduce the scattered light sensitivity of the photodetector. By combining a photodetector with high scattered light sensitivity and a photodetector with low scattered light sensitivity, the scattered light sensitivity difference Amn can be increased.

As the surface member for increasing the value of F (θ), a light scattering translucent member is suitable. Examples of the light-scattering light-transmitting member include a light-scattering surface having a high transmittance or a light-transmitting member containing a light-scattering substance. The light-scattering surface having a high transmittance can be obtained by forming irregularities on the surface of the translucent member. Examples include ground glass. Examples of the translucent member containing a light scattering substance include opal glass.

Further, examples of the surface member for reducing the value of F (θ) include a smooth surface transparent member, a flat absorption filter, a mesh, and a mesh made of a non-transparent member having a certain aperture ratio. It is preferably used. Further, these surface members may be used in combination. Here, it is desirable that any of the above surface members be installed in parallel with the light receiving surface of the photoelectric conversion element.

The smooth surface translucent member is made of a material having a high transmittance of irradiation light and a higher refractive index than air, and has a flat and smooth interface with air. Since the smooth-surface translucent member has such an interface, reflection increases as the incident angle θ increases, and the value of F (θ) decreases. As the material of the smooth surface translucent member, a translucent inorganic material such as glass or a translucent organic material such as acrylic can be used.

Further, by using a plurality of plate-shaped smooth surface light-transmissive members in a stacked manner, the number of interfaces with air can be increased,
The value of F (θ) can be further reduced. Further, in order to increase the reflectance, a thin film material having a high refractive index may be added to the surface of the smooth-surface translucent member with a film thickness that does not significantly reduce the transmittance.

The plate-shaped absorption filter is a plate-shaped filter having a certain thickness and absorption coefficient, and the internal transmittance excluding the reflection loss on the surface decreases according to the incident angle θ of light. The internal transmittance of the light of wavelength λ at an incident angle of 0 ° is τo
If (λ) and the internal transmittance at the incident angle θ is τθ (λ), then τθ (λ) = τo (λ) ^{(1 / cos (θ))} (33). Further, the flat absorption filter may also have a function of adjusting the spectral sensitivity of the photodetector used in the present invention.

The mesh is a flat plate mesh made of a non-translucent member having a certain aperture ratio. Since the non-translucent member has a thickness, the aperture ratio is reduced according to the incident angle θ, so that the value of F (θ) is reduced.

With the same aperture ratio, the thicker the non-translucent member is, the faster the aperture ratio and F (θ) are decreased by θ. The mesh is excellent in that the value of F (θ) can be lowered and the scattered light sensitivity can be lowered without changing the spectral sensitivity of the photodetector used in the present invention.

The smooth surface translucent member, the plate-shaped absorption filter, and the mesh are preferably made of materials having high durability against light, heat, moisture, acid, alkali and the like. In particular, a material having at least light resistance, preferably weather resistance, is desired so that the spectral sensitivity of the photodetector does not change due to the alteration of the material. Further, it is desirable to use one having mechanical strength that is unlikely to be deformed or damaged.

When the materials of the smooth surface translucent member, the flat plate-shaped absorption filter and the mesh have insufficient weather resistance, a surface protective material may be provided so as to cover the surface members. . As the surface protective material, a transparent material similar to the smooth surface transparent member and having a high transmittance is desirable.

The surface protective material may have a flat plate shape or a dome shape. When a flat surface protective material is used, it also functions as the smooth surface light-transmitting member.
Further, when the dome-shaped surface protective material is used, the surface protective material has a small influence on the incident angle sensitivity, and dirt is unlikely to adhere.

(Irradiation Light) The irradiation light to be measured by the light intensity measuring method of the present invention may be natural sunlight or light from an artificial light source.

(Output of Photodetector) Depending on the type of photoelectric conversion element, the output of the photodetector of the present invention may be voltage output or current output. The measurement is performed by appropriately connecting to a known measuring means such as a tester, a digital multimeter or a data logger.

Here, in the case of current output, a shunt resistor may be incorporated in the photodetector to convert it into a voltage for output. In this case, it is desirable to use a shunt resistor having a small temperature coefficient or adjust the temperature.

Further, the measuring means may be built in the light intensity measuring device and integrated.

(Case of Photodetector) It is desirable that all the members of the photodetector described above be housed in a case and integrated. It is desirable that the outside of the case and the periphery of the photodetector be glossy black so that reflected light does not enter the photodetector. It is desirable that the shape of the case is such that the irradiation light incident on the photoelectric conversion element of the photodetector is not blocked as much as possible.

Further, in the case of designing for the outdoors, it is desirable to use an airtight or waterproof case. When the temperature of the photoelectric conversion element or the shunt resistance is adjusted, a temperature adjusting mechanism such as a Peltier element can be preferably used, but it is desirable that the temperature adjusting mechanism is also housed in the case and integrated. For the power source such as the temperature adjusting mechanism, only the power source input terminal may be integrated, and the power source body may be externally attached.

(Data Processing Means of Light Intensity Measurement Method) As data processing means of data measured by the light intensity measurement method of the present invention, data capable of exchanging data with the photo detection device of the present invention such as a personal computer. It is desirable to provide processing means. Preferably, a portable data processing means is desirable.

Further, the CPU, RAM, ROM, input section,
You may provide the data processing means for exclusive use of the light intensity measuring device of this invention comprised from a display part etc. CPU is ROM
The calculation processing of the scattered light intensity, the direct light intensity, and the like is controlled based on the processing program stored in.

The dedicated data processing means may be integrated with the photodetector of the present invention to form the light intensity measuring device of the present invention. As a result, the measurement result can be immediately obtained at any place and time, and the portability is improved.

When the light intensity measuring device of the present invention is permanently installed to store data, a data storage means such as a data logger is provided and connected to the photodetector device of the present invention by a cable. It is desirable to be able to acquire and store data sequentially.

Further, the data storage means may be incorporated in the photodetector of the present invention, and the stored data may be transferred to the data processing means to process the data.

[0142]

The present invention will be described in detail with reference to the following examples, but these examples are illustrative and the scope of the present invention is not limited to these examples.

[0143]

Example 1 As an example of the light intensity measuring device of the present invention, the direct light intensity and scattered light intensity of sunlight at an arbitrary point and at an arbitrary time were measured using the device outlined in FIG.

As the photoelectric conversion element 103 of the first photodetector, a photodegraded amorphous silicon solar cell (hereinafter abbreviated as a-Si cell) is used, and as the photoelectric conversion element 104 of the second photodetector. Was a crystalline silicon solar cell (hereinafter abbreviated as c-Si cell).

Here, in the a-Si cell, a glass called BK7 which is a kind of borosilicate crown glass having a thickness of 3 mm is used as a substrate to form a transparent electrode, and then an amorphous silicon semiconductor layer is formed by a CVD method. The back electrode is formed so that light is incident from the glass substrate side.

Therefore, the surface member 105 of the first photodetector.
Serves as the glass substrate of BK7. Note that a-Si
The cell has an area of 1 cm ² and 1 sun at 100 at 100 ° C.
The one whose characteristics were stabilized by photo-deterioration for 0 h was used.

As the surface member 106 of the second photodetector, as an example of a flat absorption filter, a color glass filter CAW-500 (thickness: 1 m, manufactured by HOYA Co., Ltd.) is used.
m) and HA-50 (thickness 3 mm) were overlapped and used. c
An -Si cell having an area of 1 cm ² was also used.

When the spectral sensitivities of both the detectors were measured by a known spectral sensitivity measurement method with the surface member attached, the results shown in FIG. 2 were obtained. By combining the filter with the c-Si cell, it was possible to give a spectral sensitivity similar to that of the a-Si cell.

Further, aluminum was used for the case of the light intensity measuring device, and the surface was subjected to black alumite treatment.
In addition, a shunt resistor having a small temperature coefficient of 1Ω was installed inside the case, and the short-circuit current of the a-Si cell and the c-Si cell was converted into a voltage and output. The output terminals 108, 109, 110 and 111 of the respective photodetectors are provided on the side surface of the case. In this embodiment, the temperature control mechanism for the photoelectric conversion elements is not provided in the light intensity measuring device, and T is provided on the back surface of both photoelectric conversion elements.
Attach a type thermocouple, measure the temperature, from the temperature coefficient of the short-circuit current of both photoelectric conversion elements measured in advance,
The resulting temperature was corrected.

Further, the case of the light intensity measuring device was provided with an aluminum block portion, which was arranged on the back surface of the photoelectric conversion element and adhered to increase the heat capacity of the photoelectric conversion element to moderate the temperature change.

Before measuring sunlight using the above light intensity measuring device, first, using a pseudo-sunlight source (solar simulator), the incident angles of the sensitivities of the two photodetectors with respect to almost parallel light are measured. The dependence was measured. As a result, the deviation F (θ) of the relative sensitivity from the cosine law with respect to the incident angle θ is shown in FIG.

In FIG. 3, reference numeral 301 is a deviation F (θ) from the cosine law of a photodetector using an a-Si cell, and 302 is a photodetector using a c-Si cell. As shown in FIG. 3, the photodetector in which a filter was added to the c-Si cell had a lower F (θ) at the incident angle θ and a lower relative sensitivity.

As a surface member of the c-Si cell,
Since the two plate-shaped absorption filters are used, it is considered that the main factor is a decrease in internal transmittance at the incident angle θ. Further, when the difference Fmn (60 °) from the deviation from the cosine law is calculated according to the equation (25) from the relative sensitivities of both photodetectors at the incident angle of 60 °, Fmn (60
°) = 0.12. From this experiment, the difference Cmn (θ) in the incident angle sensitivities of both photodetectors at the incident angle θ was clarified.

Next, the above-mentioned light intensity measuring device is installed outdoors so that the incident angle of the direct light of sunlight is 0 ° (vertical incident on the light receiving surface), and the scattered light state The outputs Pm and Pn (here, the voltage conversion value of the short-circuit current) of both photodetectors were measured at various different dates.

For comparison, the scattered radiation intensity Es at the same time was measured by a scattering pyranometer (one whose direct light was blocked by MS801 manufactured by Eiko Instruments Inc.) installed on the same automatic tracking mount. The value of the scattered light intensity Es by the scattering pyranometer is taken on the horizontal axis, the normalized output difference ΔPmn of both photodetectors is calculated by the following formula (5) and taken on the vertical axis to create a graph, It is shown in FIG.

As is clear from FIG. 4, ΔPmn and Es
Showed a very good correlation. In this experiment, the incident angle is 0
Since it is °, Cmn (θ) = 0. Therefore, the formula (1
0), the slope of ΔPmn with respect to Es in the graph of FIG. 4 represents Amn, and Amn could be experimentally obtained by obtaining an approximate curve of the correlation between ΔPmn and Es. Further, when the variation of Es with respect to the approximate curve was obtained, it was within ± 5%.

Since the incident angle sensitivity difference Cmn (θ) and the scattered light sensitivity difference Amn were found from the above-mentioned experiment on the incident angle dependence and the slope of the graph of FIG. 4, the normalized output difference was obtained from the equation (10). By measuring ΔPmn and calculating the incident angle θ, it becomes possible to measure the scattered light intensity Es incident on an arbitrary surface.

In the graph of FIG. 4, since the incident angle θ was 0 °, the inclination of the graph was Amn, and when Es = 0, ΔPmn = 0, but when the incident angle was θ, From the equation (10), the slope of ΔPmn with respect to Es is (Am
n-Cmn (θ)), and ΔPmn at Es = 0 is C
It becomes mn (θ) · Et.

Here, the position of the sun on the sky at an arbitrary point and at an arbitrary time can be calculated from a latitude, longitude, and time information by a known method. In recent years, GPS (Global Pos
itioning System), it has become easy to obtain latitude, longitude, and time information at any point.

Therefore, if the azimuth and inclination angle of the installation surface of the light intensity measuring device of the present invention are known, it is easy to calculate the incident angle θ. Further, if installed on a horizontal surface, the orientation of the installation surface may be unknown. Also, the sun position and incident angle θ
May be calculated at a later date even if it is not on the spot.

Therefore, at any point at any time,
Using the light intensity measuring device of the present invention, the normalized output difference ΔPm
The scattered solar radiation intensity Es can be measured only by measuring n. Further, since the total solar radiation intensity Et of the installation surface can be measured from the output values of both photodetectors, the direct solar radiation intensity can also be calculated from both measured values.

As is apparent from FIG. 1, the light intensity measuring device of the present invention is compact, convenient to carry, has no driving part, and does not require adjustment of the installation direction. Therefore, it is most suitable for measuring scattered solar radiation intensity and total solar radiation intensity in the field.

At the time of measurement of sunlight shown in the graph of FIG. 4, the total solar radiation spectrum of the sun tracking surface was measured by using a spectroradiometer, and it was compared with the standard AM1.5 spectrum described in JIS. And the mismatch coefficient M defined by the equation (32) between the two photodetectors.
When the mnt was calculated, it was 0.995 to 1.006.

Further, the spectrum of the solar simulator measuring the incident angle dependence was measured, and the mismatch coefficient Mm between the photodetectors and the total solar radiation spectrum was measured.
As a result of calculating nc according to the equation (31), 0.9
It was 9 to 1.008.

These results show that the spectral mismatch error is sufficiently small because the spectral sensitivities of the two photodetectors are close to each other. Since both photodetectors have similar spectral sensitivities and the mismatch coefficient is close to 1, the accuracy of the measurement result of scattered solar radiation intensity is improved.

Further, by using the plate-shaped absorption filter, the difference in the scattered light sensitivity of the photodetector can be increased and the measurement accuracy of the scattered light intensity is improved.

[0167]

Comparative Example 1 In Example 1, a photodetector having a spectral sensitivity deviated from the spectral sensitivity of the a-Si cell used in the first photodetector was used as the second photodetector. Second
As the photoelectric conversion element of the photodetector of
-Si cell is used, and as the surface member 106, a color glass filter LA-120 manufactured by HOYA Co., Ltd. (thickness 2.5
mm) and HA-50 (thickness 3 mm) were used by stacking.

Similar to the first embodiment, the mismatch coefficient Mmnc
Was calculated to be 0.97 to 1.025. Further, when the variation of Es with respect to ΔPmn was calculated in the same manner as in Example 1, it was within ± 15%.

[0169]

Second Embodiment In the first embodiment, c-Si cells 601 and 60 are used as photoelectric conversion elements of the first and second photodetectors.
2 is used as the surface member of the first photodetector, a flat glass plate 603 whose material is white plate glass and has a thickness of 1 mm, a light incident side is a polished surface, and a photoelectric conversion element side is a rough surface. As a surface member of the detector, as an example of a smooth-surface translucent member, a plurality of flat glass plates 604 (hereinafter abbreviated as double-sided polished glass), which have the same material and thickness and both surfaces are polished, are stacked. used.

The number of double-sided polishing glass 604 is from 1 to 6
The incident angle dependence of both photodetectors was measured in the same manner as in Example 1 by changing the number of sheets up to the number of sheets, and the difference Fmn (6) from the deviation from the cosine law was measured.
0 °) was calculated. Similar to the first embodiment, ΔPmn and Es
The scattered insolation intensity E from ΔPmn according to the approximate curve of the correlation of
s is calculated and compared with Es measured by a scatter pyrometer,
The variation x (± x%) of the measured value of the scattered solar radiation intensity Es by both measurement methods was obtained. Depending on the number of double-sided polished glass, the value of Fmn (60 °) and the above Es for ΔPmn
The variation x of is plotted in a graph and shown in FIG. In FIG. 5, the number next to each point in the graph indicates the number of double-sided polished glasses.

As is clear from FIG. 5, the value of Fmn (60 °) increases as the number of double-sided polished glasses increases, and when Fmn (60 °) ≧ 0.06, the variation of Es sharply decreases. , Es measurements are now accurate. This is because the number of double-sided polished glasses increased, the number of interfaces between the smooth-surface translucent member and air increased, and the internal transmittance of the glass filter decreased. Deviation from the cosine law depending on the angle of incidence increases, and the scattered light sensitivity of the second photodetector decreases, and the first and second
It is considered that this is because the difference in the scattered light sensitivity of the photodetector of No. 2 increased. As described above, by using the smooth-surface translucent member, the scattered light sensitivity can be changed while suppressing the change in the spectral sensitivity of the photodetector, and the measurement accuracy of the scattered light intensity can be improved. In addition, it could also function as a surface protective material.

[0172]

[Third Embodiment] In the first embodiment, as the photoelectric conversion elements of the first and second photodetectors, thermocouples 701 and 702 similar to those generally used in a pyranometer are used, and first photodetection is performed. A transparent, hemispherical dome 703 having a material of BK7 and a thickness of 1 mm is used as a surface member of the vessel, and a second photodetector in addition to the dome 704 is used as a surface member of the second photodetector. On the light incident side of the photoelectric conversion element of the container, inside the dome, a flat plate-shaped mesh 705 of stainless steel with an aperture ratio of 80% and coated with matte black was provided in parallel with the light receiving surface of the photoelectric conversion element.

The domes 703 and 704 also serve as a surface protective material. Since the temperature coefficient of the photoelectric conversion element of the photodetector was small in this example, the temperature adjusting mechanism and the temperature measuring mechanism were omitted. Further, since the photodetector of this example has a voltage output, the shunt resistor used in Example 1 was unnecessary.

In this embodiment, by using a mesh, the spectral sensitivities of both photodetectors differed in absolute value, but almost matched in relative value with respect to wavelength. Therefore, the mismatch coefficient was 1.00 for both Mmnc and Mmnt, and the measurement error of the scattered light intensity due to the difference in spectral sensitivity could be reduced.

The incidence angle dependence of both photodetectors was measured in the same manner as in Example 1, and the difference in deviation from the above cosine law Fmn (60 °)
As a result of calculation, Fmn (60 °) = 0.17.
Further, when the variation of the scattered solar radiation intensity Es with respect to ΔPmn was calculated in the same manner as in Example 1, it was within ± 4%.

[0176]

Example 4 Amorphous silicon germanium photoelectric conversion layers 801 and 802 were formed as photoelectric conversion elements of the first and second photodetectors on a metal substrate having a light reflection layer, and a As with the -Si cell, a photo-degraded one was used.

Here, the light reflection layer reflects, in the incident light, long-wavelength light, which has passed through the photoelectric conversion layer of amorphous silicon germanium, into the photoelectric conversion layer again,
It has a function of improving the photosensitivity of the photoelectric conversion layer. For the first photodetector, a photoelectric conversion layer 801 is formed on a metal substrate 803 having light-scattering unevenness, which has a light-reflecting layer having light-scattering unevenness. The detector used was one in which the photoelectric conversion layer 802 was formed on a mirror-finished metal substrate 804 provided with a mirror-finished light reflection layer.

As a result of using the substrate having the unevenness in the first photodetector, unevenness for scattering light was also formed on the light incident side surface of the photoelectric conversion element. The light intensity measuring device of the present embodiment,
Since it is supposed to measure the irradiation light by indoor lighting, it is considered that the temperature change due to the irradiation light and the temperature is small, so the temperature adjustment mechanism and the temperature measurement mechanism of the photoelectric conversion element are omitted,
We have made it even more compact.

In addition, in this example, the scattered light intensity and the direct light intensity of the indoor lighting system using a plurality of metal halide lamps were measured.

In the same manner as in Example 1, the incident angle was 0 °,
The correlation between ΔPmn and Es was obtained, and Amn was obtained experimentally. When obtaining the correlation, the scattered light intensity Es was obtained by attaching a tube for extracting only the direct light to the second photodetector, measuring the direct light intensity, and subtracting the direct light intensity from the total irradiation light intensity.

Further, in the experiment for obtaining the correlation, a single-light type metal halide lamp was used, a cylindrical wall for shielding scattered light was provided around the light intensity measuring device, and the height of the wall was changed to scatter the light. The light intensity was changed.

By the value of Amn obtained experimentally,
By measuring ΔPmn, it was possible to measure the scattered light intensity and the direct light intensity of arbitrary indoor irradiation light. Here, in the measurement, the light intensity measuring device is made to face the arbitrary indoor lighting system.

[0183]

Fifth Embodiment The photodetector used in the first embodiment is used as the first and second photodetectors, and the third and fourth photodetectors are used.
The photodetector used in Example 3 excluding the hemispherical dome was used to construct a light intensity measuring device composed of four photodetectors.

A transparent, hemispherical dome having a material of BK7 and having a thickness of 1 mm was provided so as to cover all of the four photodetectors, and used as a surface protective material. Further, the back surfaces of the four photodetectors were brought into contact with an aluminum block, and the temperature of the aluminum block was adjusted to 25 ° C. ± 2 ° C. by a Peltier element. By adjusting the temperature of the photodetector, it is not necessary to correct the temperature dependence of the output of each photoelectric conversion element.

In the same manner as in Examples 1 and 3, it was possible to measure the total solar radiation intensity and the scattered solar radiation intensity of sunlight on an arbitrary surface. The total solar radiation intensity can be easily compared with the conventional global pyranometer by using the third photodetector. Further, the first and second photodetectors have a quicker response of the output change with respect to the time change of the light, as compared with the third and fourth photodetectors. The change of scattered solar radiation intensity was also detected.

On the other hand, for the average scattered solar radiation intensity for a certain time, the scattered solar radiation intensity obtained from the first and second photodetectors and the scattered solar radiation intensity obtained from the third and fourth photodetectors are used. By averaging, the measurement accuracy of the scattered solar radiation intensity was further improved. In addition, the dome improved the weather resistance of the light intensity measuring device and made it less likely to become dirty.

The present invention has the following effects.

According to the light intensity measuring method and device of the present invention, the light intensity measuring device has high portability, low cost, no adjustment or maintenance, and is robust. Moreover, the measurement of the direct light intensity and the scattered light intensity became accurate.

Since the spectral sensitivities of the photodetectors used as a pair are close to each other, the direct light intensity and the scattered light intensity can be measured more accurately.

Further, when the sensitivity at the incident angle of 0 ° of the photodetectors used as a pair is 1, the deviation from the cosine law of the relative sensitivity at the incident angle of 60 ° is 0.06 with respect to each other.
Due to the above differences, the measurement of direct light intensity and scattered light intensity became more accurate.

[0191]

Other Embodiments The present invention is applicable to a plurality of devices (eg, host computer, interface device, reader,
It may be applied to a system composed of an image recording device or the like) or to a device composed of one device.

Another object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Alternatively, by the CPU or MPU) reading and executing the program code stored in the storage medium,
It goes without saying that it will be achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instruction of the program code,
An operating system (OS) running on the computer does some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the above-mentioned storage medium, the storage medium stores the program code corresponding to the flowchart described above (FIG. 9).

[0195]

As described above, according to the present invention,
It is possible to provide a measuring method and a measuring device capable of accurately measuring the scattered light intensity. Further, it is possible to provide a measuring method and a measuring device capable of measuring the direct light intensity. Furthermore, it is possible to provide a measuring device and a measuring method thereof that have high portability, low cost, and no adjustment or maintenance required.

[Brief description of drawings]

FIG. 1 is a schematic diagram conceptually explaining an example of a light intensity measuring device of the present invention.

2 is a graph showing the spectral sensitivity of the photodetector used in Example 1. FIG.

FIG. 3 is a graph showing an example of a change in deviation from a cosine law of relative sensitivity with respect to an incident angle of a photodetector that constitutes the light intensity measuring device of the present invention.

FIG. 4 is a diagram showing an example of changes in a normalized output difference ΔPmn of a photodetector with respect to scattered light intensity Es.

FIG. 5 is a difference Fmn in deviation from the cosine law when the number of smooth-surface translucent members is changed in the experiment of Example 2.
It is a graph which shows the result of the dispersion | variation of the measurement result of (60 degree) and scattered light intensity Es.

FIG. 6 is a schematic diagram for conceptually explaining the light intensity measuring device according to the second embodiment.

FIG. 7 is a schematic diagram conceptually illustrating a light intensity measurement device of Example 3.

FIG. 8 is a schematic diagram conceptually illustrating a photoelectric conversion element of a light intensity measurement device of Example 4.

FIG. 9 is a flowchart illustrating a method for calculating scattering intensity and direct intensity by the light intensity measuring device of the present invention.

[Explanation of symbols]

101 first photodetector 102 second photodetector 103 photoelectric conversion element 104 of first photodetector 104 photoelectric conversion element 105 of second photodetector 105 surface member 106 of first photodetector surface member of second photodetector 107 Cases 108 and 109 of the light intensity measuring device Output terminals 110 and 111 of the first photodetector Output terminals 118 and 119 of the second photodetector Input terminals 120 and 121 of the first photodetector output Second photodetector output Input terminal 150 of the data processing unit 201 Spectral sensitivity of the first photodetector of the first embodiment 202 Spectral sensitivity of the second photodetector of the first embodiment 301 From the cosine law of the relative sensitivity of the first photodetector of the first embodiment Deviation 302 from deviations cosine law 601 and 602 of the relative sensitivity of the second photodetector of Example 1 Photoelectric conversion element 603 of the light intensity measuring device of Example 2 Surface member of the first photodetector of Example 2 604 of Example 2 Surface members 701 and 702 of second photodetector Photoelectric conversion element 703 of light intensity measuring device of Example 3 Surface members 704 and 705 of first photodetector of Example 3 Surface of second photodetector of Example 3 Member 801 Photoelectric conversion layer 802 of first photodetector of Example 4 Photoelectric conversion layer 803 of second photodetector of Example 4 Substrate 804 of photoelectric conversion element of first photodetector of Example 4 Substrate of photoelectric conversion element of second photodetector

Claims (24)

[Claims] 1. A method of measuring the intensity of irradiation light, comprising: using a plurality of photodetectors provided on a predetermined surface, having parallel photodetection reference planes, and having different detection sensitivities to scattered light; A light intensity measuring step of measuring irradiation light; and a scattered light intensity calculating step of calculating scattered light intensity (Es) based on outputs of a plurality of photodetectors having different detection sensitivities to the scattered light. And the method of measuring light intensity. 2. The scattered light intensity calculation step includes a step of calculating an output difference from the outputs of the plurality of photodetectors, and the scattered light intensity is calculated using the output difference. The light intensity measuring method according to claim 1. 3. The scattered light intensity calculation step includes a step of calculating a normalized output difference based on outputs of the plurality of photodetectors, and the scattered light intensity is calculated using the normalized output difference. The light intensity measuring method according to claim 1, wherein 4. The light intensity measuring method according to claim 1, wherein the plurality of photodetectors have different detection sensitivities depending on an incident angle of the irradiation light. 5. The light intensity measurement according to claim 1, wherein the plurality of photodetectors have a uniform sensitivity with respect to an azimuth angle of the irradiation light. Method. 6. The spectral sensitivities of the plurality of photodetectors have a mismatch coefficient of 0.9 indicating a deviation between the spectral sensitivities.
The light intensity measuring method according to any one of claims 1 to 5, wherein the light intensity measuring method is controlled so as to be 8 or more and 1.02 or less. 7. When the sensitivity at an incident angle of 0 ° of the photodetector is 1, the deviation from the cosine law of the relative sensitivity at an incident angle of 60 ° with respect to the sensitivity of the photodetector at an incident angle of 0 ° is calculated by The light intensity measuring method according to claim 1, wherein, when a photodetector is used, the difference between the deviations generated in each photodetector is 0.06 or more. . 8. The direct light intensity (Ed) of the irradiation light incident on the predetermined surface is calculated based on the scattered light intensity (Es). The method for measuring light intensity according to item. 9. A light intensity measuring device for measuring the light intensity of irradiation light, comprising a plurality of light detections, which are provided on a predetermined surface and have light detection reference planes parallel to each other, and which have different detection sensitivities to scattered light. And a scattered light intensity calculating means for measuring scattered light intensity (Es) based on the outputs of a plurality of photodetectors having different detection sensitivities to the scattered light. 10. The light intensity measuring device according to claim 9, wherein the plurality of photodetectors have different detection sensitivities depending on the incident angle of the irradiation light. 11. The light intensity measuring device according to claim 9, wherein the plurality of photodetectors have a uniform sensitivity to an azimuth angle of the irradiation light. 12. The spectral sensitivity of each of the plurality of photodetectors has a mismatch coefficient of 0.
The light intensity measuring device according to any one of claims 9 to 11, wherein the light intensity measuring device is controlled to be 98 or more and 1.02 or less. 13. When the sensitivity of the photodetector at an incident angle of 0 ° is 1, the deviation from the cosine law of the relative sensitivity at an incident angle of 60 ° with respect to the sensitivity at an incident angle of 0 ° of the photodetector is different from the above-mentioned plurality of deviations. 13. The light intensity measuring device according to claim 9, wherein when a photodetector is used, the difference between the deviations generated in each photodetector is 0.06 or more. . 14. The light intensity according to claim 9, wherein the direct light intensity of the irradiation light incident on the predetermined surface is calculated based on the scattered light intensity. measuring device. 15. The photodetector has a photoelectric conversion element,
A surface on which the photoelectric conversion element receives the irradiation light, and /
15. The light intensity measuring device according to claim 9, wherein the detection sensitivity of the photodetector to the scattered light is changed depending on the surface texture of the back surface thereof. 16. The photodetector includes a photoelectric conversion element and a translucent member that covers the photoelectric conversion element, and the translucent member changes the detection sensitivity of the photodetector with respect to the scattered light. The light intensity measuring device according to claim 9, wherein 17. The photodetector has a photoelectric conversion element and a filter, and the detection sensitivity of the photodetector with respect to the scattered light is changed by the filter. The light intensity measuring device according to any one of 1. 18. The photodetector includes a photoelectric conversion element and a mesh, and the detection sensitivity of the photodetector with respect to the scattered light is changed by the mesh. The light intensity measuring device according to any one of 1. 19. The photodetector includes a photoelectric conversion element and a light-scattering transparent member, and the light-scattering transparent member changes the detection sensitivity of the photodetector to the scattered light. The light intensity measuring device according to any one of claims 9 to 18, which is characterized. 20. The light intensity measuring device according to claim 9, which is further portable. 21. A program for realizing the measuring method for measuring the light intensity according to claim 1. 22. A computer-readable storage medium storing a measurement processing program for controlling a measurement processing of light intensity of irradiation light, wherein the measurement processing program is provided on a predetermined surface, and detects light parallel to each other. Having a surface, using a plurality of photodetectors with different detection sensitivity to scattered light, a light intensity measurement step of measuring the irradiation light, based on the output of a plurality of photodetectors with different detection sensitivity to the scattered light And a scattered light intensity calculation step of calculating scattered light intensity (Es). 23. A photodetector for measuring the light intensity of irradiation light, comprising a plurality of photodetectors provided on a predetermined surface and having photodetection surfaces parallel to each other and having different detection sensitivities to scattered light. A photodetector characterized by having. 24. A data processing device for processing a measured value of the light intensity of irradiation light, comprising: receiving means for receiving outputs from a plurality of photodetectors having different detection sensitivities to scattered light; And a scattered light intensity calculating means for calculating scattered light intensity (Es) based on outputs from the plurality of photodetectors.