JPH0799344B2 - Photometric device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric device that accurately measures the brightness perceived by humans in the mesopic region.

2. Description of the Related Art Conventionally, in a photometric system, a value (luminance) measured by a photodetector having a sensitivity characteristic matching the standard relative luminous efficiency Vλ has been used to represent the brightness of a reflector or a light emitter. This Vλ
Is determined as a representative value of the spectral sensitivity characteristic of the human eye in the photopic region.

In recent years, in the lighting field, photometry corresponding to various visual environments has become necessary. Of these, the scotopic visibility function V′λ is defined in the scotopic region, and the standard relative luminous efficiency Vλ and the scotopic sensitivity function V′λ are associated with each other at a wavelength of 555 nm and quantitatively. It is set. The mesopic region is located between the photopic region and the scotopic region, the spectral sensitivity characteristics of the human eye change depending on the level of brightness, and the wavelength showing the maximum sensitivity approaches the scotopic region. Shift to shorter wavelengths. For this reason, the brightness perceived by humans with respect to color light does not match the value (photometric amount) measured by a light receiver having a spectral sensitivity characteristic of Vλ or V′λ.

Therefore, as a method for measuring the brightness perceived by humans in the mesopic region as equivalent luminance, there is a conventional device having the configuration shown in FIG. The photometric device of FIG. 11 will be described below. In FIG. 11, 1 is a light receiver, 2 is a light receiver, 3
Is a light receiver, 4 is a V′λ light receiver, 5 is a chromaticity calculation unit, 6 is a correction coefficient c calculation unit, 7 is an L _bP calculation unit, 8 is an L _bS calculation unit, 14
Is an adaptation coefficient a calculation unit, and 11 is an L _bm calculation unit. FIG. 12 shows a specific structure of the photodetector in FIG. 11, 1a being ₁ photodetector, 1b being ₂ photodetectors, and 1c being an adding circuit.

Further ₁ photodetector 1a sensitivity characteristic correction filter 1a _1, the light receiving element 1a ₂ and operational amplifier 1a ₃ of the current - constituting voltage conversion amplifier circuit. The _two light receivers 1b, the light receivers 2, the light receivers 3, and the V'λ light receivers 4 are the same in configuration as the _one light receiver 1a except for the characteristics of the spectral characteristic correction filter. FIG. 13 shows a specific configuration of the correction coefficient c calculation unit 6 shown in FIG. 11, which includes the coding circuit (1) 6a, the coding circuit (2) 6b, and the correction coefficient c table memory 6c. Constitute. FIG. 14 shows a specific configuration of the adaptation coefficient a calculation unit 14 in FIG. 11, which includes an L 1 range limiting unit 14a, an L _bS range limiting unit 14b, an L _bS encoding circuit 14c, and an L _bS encoding circuit 14.
d, Adaptation coefficient a Table memory 14e. FIG. 15 shows a specific configuration of the L _bm calculation unit 11 in FIG. 11, which includes an exponent separation unit (1) 11a, a logarithmic conversion unit (1) 11c, and an addition unit (1) corresponding to the L _bP signal system. ) 11e, exponent separation unit (2) 11b corresponding to the L _bS signal system, logarithmic conversion unit (2) 11d, addition unit (2) 11f, (1-a) calculation unit 11i, multiplication unit (1)
11g, a multiplication unit (2) 11h, an addition unit (3) 11j, an exponent separation unit (3) 11k, an antilogarithmic conversion unit 11l and a synthesis unit 11m. The operation of the conventional photometric device configured as described above will be described below.

The incident light from the object to be measured is received by four types of photoreceivers (photoreceiver, photoreceiver, photoreceiver, V'λ photoreceiver) having spectral sensitivity characteristics as shown in FIG. The brightness of the measurement target can be measured by limiting the measurement range with a lens system or a light shielding tube and limiting the light incident on the light receiver.
Of these, the photodetector has a wavelength of 500 nm, as shown in Fig. 18.
Is separated into a short wavelength side and a long wavelength side, and the short wavelength side is received by _one light receiver and the long wavelength side is received by the light receiver. In the light receiver, the output of the _first light receiver 1a and the output of the _second light receiver 1b are weighted by the relative sensitivity shown in FIG. 18, and added by the adding circuit 1c. In each light receiver, the spectral sensitivity characteristic shown in FIG. 18 is realized by combining the transmission characteristic of the sensitivity correction filter and the spectral sensitivity characteristic of the light receiving element, and converted into a voltage value by the current-voltage conversion amplifier circuit of the operational amplifier.

The output X from the light receiver 1, the output Y from the light receiver 2, and the output Z from the light receiver 3 are supplied to the chromaticity calculator 5. The chromaticity calculation unit 5 obtains chromaticity (x, y) from the following equation.

x = X / (X + Y + Z) (1) y = Y / (X + Y + Z) (2) Further, the output (x, y) of the chromaticity calculator 5 is supplied to the correction coefficient c calculator 6. The correction coefficient c calculation unit 6 obtains a correction coefficient for converting the measured value into the brightness that humans perceive by the physiological effect of the color information. As this correction coefficient,
The coefficients proposed by Ware and Cowan (hereinafter W & C) of the National Research Institute of Canada (NRC) are general. In this embodiment, the correction coefficient calculated by the W & C formula is used. The correction coefficient c is used to obtain a correction value for the brightness and luminance that humans perceive based on the color information from the measurement target, and is obtained by the equation (3). The expression (3) is standardized at 570 nm.

The correction coefficient c calculation unit 6 has a correction coefficient c table memory 6c in order to execute the calculation of the equation (3) in a short time. The outputs (chromaticity) x and y from the chromaticity calculation unit 5 take only numerical values in the range of 0 to 1. Therefore, the expression degree x is supplied to the coding circuit (1) 6a of the correction coefficient calculation unit 6 and divided into 100 steps or more to code. For example, if it is divided into 100 steps, 0 to 0.01 is set as one group and the representative value is x.
_c1 0.01 to 0.02 is set as the next group, and the representative value is treated as x _c2 . Similarly, the chromaticity y is also coded by the coding circuit (2) 6b and one representative value X _ci , y _ci is set for each group. The correction coefficient c is calculated in advance using the coded chromaticity representative values x _ci , y _ci using the equation (4), and stored in the correction coefficient c table memory. During measurement,
The measured value (x, y) is coded, the table memory is accessed, and the correction coefficient c is read. As a result, the measured value (x, y)
If is input to the correction coefficient c calculation unit 6, the correction coefficient c can be obtained in a short time without performing the calculation of the equation (3) during measurement. The number of divisions of the coding circuits 6a and 6b may be set according to the accuracy of the correction coefficient c to be obtained. If the number of divisions is increased, the calculation accuracy of the correction coefficient c is improved.
In general, 100 or more divisions are sufficient for calculation accuracy.

Next, the output C of the correction coefficient c calculation unit 6 and the output Y of the light receiver 2 are supplied to the L _bP calculation unit 7. Since the light receiver has the spectral sensitivity characteristic of the standard relative luminous efficiency Vλ shown in FIG. 18, the output Y of the light receiver 2 represents the luminance value L _P. The L _bP calculator 7 obtains the equivalent luminance L _{bP in photopic} vision based on the equation (4).

L _bP = L _P · C (4) On the other hand, the output L _S from the V′λ light receiver 4 is supplied to the L _bS calculation unit 8. The scotopic luminosity function is a spectral sensitivity characteristic of the human eye corresponding to a region having a low brightness level, and has little color information. Therefore, the equivalent luminance L _bS in the scotopic region is calculated using the equation (5).

_{L bS = K · L S (} K: constant) (5) Next, L _bS output L _bS calculation unit 7, the output L _bS of L _bS calculator 8
Is supplied to the adaptation coefficient a calculator 14. The adaptation coefficient a calculation unit, L _bP in L _bP range restriction section 14a and the L _bS range restriction section 14b
Limit the range of values and L _bS values. The logarithmic values of L _bP and L _bS are coded by the L _bP coding circuit 14c and the L _bS coding circuit 14d, and the values corresponding to the _coded L _bP and L _bS are combined to access the adaptation coefficient a table memory. , Read out the adaptation coefficient a. Adaptation coefficient a in the adaptation coefficient a calculator 14
The calculation method of will be described with reference to FIG. Fig. 16 is a curve showing the relationship between the adaptation coefficient a and the equivalent luminance (L _b ) and is obtained by an observation experiment with 20 or more people in the color light of the mesopic level. The horizontal axis shows the equivalent luminance and the vertical axis shows the adaptation coefficient. a.
The adaptation coefficient a is the measured value L _bPi of the equivalent luminance in the photopic region.
A logarithm log L _BPI of connected by a straight line the logarithm log L _bsi measurements L _bSi equivalent brightness in scotopic vision region can be obtained as a value a _i for the intersection A between the curve of the adaptation coefficient a. The adaptation coefficient a can be graphically and easily obtained as shown in FIG. 16, but in order to obtain it by calculation, it is necessary to perform a complicated calculation. Further, in principle, both L _bpi and L _bsi can take a numerical value of 0 to ∞, so that the calculation target range is wide and the calculation becomes complicated. Therefore, the possible range of L _bp and L _bs is limited to the mesopic region. The calculation target range L _bs in L _bs range restriction section 14b, is limited to _{^{0.003cd / m 2 ≦ L bs ≦}} 300cd / m 2, the calculation target range L _bs in L _bp range restriction section 14a, 0.0
[0014] Limited to 1 cd / m ² ≤ L _bp ≤ 14.1 cd / m ² , the change range is 10 ⁵ . Generally, the range of mesopic viewing area is equivalent brightness 0.00
Since it is 3 cd / m ^{2 to} 14.1 cd / m ^2, it is a range that can sufficiently cover the change range of 10 ⁵ .

Such a combination of L _bp and L _bs is handled on the adaptation coefficient a table memory 14e as shown in FIG. In the adaptation coefficient a table memory 14e, the coded L _bp and L
_{Using bs} as the address of the table memory, the data of the adaptation coefficient a is stored in the area indicated by this address and read at the time of measurement. For example, if L _bp = L _bpi and L _bs = L _bsi , the data of the adaptation coefficient a of the address indicated by a _i in FIG. 12 is read.

Next, the output of the adaptation coefficient a calculator 14 and the L _bp calculator 7 and L
The output of the _bs calculation unit 8 is supplied to the L _bm calculation unit 11. The L _bm calculation unit 11 obtains the equivalent brightness L _bm in mesopic vision according to the equation (6).

L _bm = L _bp ^a · L _bs ^(1-a) (6) In the L _bm calculation unit 11, the equations (6) and (7) are changed to L
_{Find bm} .

log L _bm = a log L _bs + (1-a) log L _bp (7) The L _bp signal input to the L _bm calculation unit 11 is the exponent separation unit (1).
In 11a, the mantissa part (absolute value is less than 1) and the exponent part (integer) are separated. The mantissa part is further supplied from the exponent separation part (1) 11a to the logarithmic conversion part (1) 11c, and the exponent part is added to the addition part (1) 1
Supplied to 1e. The logarithmic conversion unit (1) 11c converts the mantissa part into a logarithm. The logarithmically converted mantissa part is the addition part (1) 11
It is added to the exponent part at e to obtain the log L _bp value. L _bs likewise index separation unit (2) 11b, the logarithmic conversion unit (2) 11d, seek log L _bs by an adder (2) 11f. For the output value a of the adaptation coefficient a calculation unit 12, the (1-a) calculation unit 11i obtains the (1-a) value. In the multiplication unit (1) 11g, the output log L of the addition unit (1) 11e
The second term (1-a) · log L _bp of the equation (8) is obtained from _bp and the output (1-a) of the (1-a) calculation unit 11i. In addition, in the multiplication unit (2) 11h, the output log L _{bp of the} addition unit (2) 11f
And a value, a · log L _bs of the first term of the equation (8) is obtained.
Further, the adder (3) 11j calculates the right side of the equation (8) from the output of the multiplier (1) 11g and the output of the multiplier (2) 11h. The output of the adder (3) 11j is supplied to the exponent separator (3) 11k and separated into an integer part (exponent part) and a decimal part (mantissa part). As a result, the mantissa takes only numerical values from 0 to 1, and the antilogarithmic conversion unit 11l performs antilogarithmic conversion. The output of the antilogarithmic transformation unit 11l and the exponential output of the exponent separating unit (3) 11k are supplied to the synthesizing unit 11m, and the equivalent luminance L _bm value in the _mesopic region is obtained.

Problems to be Solved by the Invention A first problem of the present invention is as follows. Since the conventional photometric device obtains the equivalent luminance in the mesopic region (0.003 cd / m ^{2 to} 14.1 cd / m ² ), the equivalent luminance L _bp in the photopic region is calculated.
Is a relative value in the range of 10 ⁵ (0.000141 cd / m ² ≦ L _bp ≦ 14.1 cd /
m ²⁾ takes the equivalent luminance L _bs in scotopic region by a relative value taking the ¹⁰⁵ range _{^{(0.003cd / m 2 ≦ L bs}} ≦ 300cd / m 2), for the values within these ranges In the mesopic region, the adaptation coefficient a is obtained. Therefore, 10 ⁵ changes in L _bp and 1 change in L _Ps
It was necessary to store the value of the adaptation coefficient a when the respective changes of 0 ⁵ were combined. As a result, there is a memory area for a combination that is rarely used during measurement, for example, a combination where L _bp is maximum and L _bs is minimum, and as a result, a large memory capacity is required.

The second object of the present invention is as follows. That is,
When the adaptation coefficient a is calculated, the adaptation coefficient a calculation curve used has a negative slope. Therefore, in the calculation of a using the table memory, when the measurement target is colored light, the photopic equivalent luminance L
The values of _bp and the scotopic equivalent luminance L _bs change, and the calculation accuracy of the adaptation coefficient a differs depending on the magnitude relationship between the measured values of L _bp and L _bs . That is, if L _bp > L _bs (red light), then L _bp <L
_As compared with _bs (blue light), there is a problem that the calculation resolution of the adaptation coefficient a decreases and the calculation accuracy deteriorates.

Means for Solving the Problems The present invention solves the above problems.

For the first problem, L _bp and L _bs are normally present in colored light.
Taking advantage of the theoretically limited difference between
An object of the present invention is to provide a photometric device that calculates the adaptation coefficient a in the mesopic region with a small memory capacity and measures the equivalent luminance in the mesopic region.

The present invention for the first object is to provide four types of photodetectors having a color matching function, and a spectral sensitivity corresponding to the scotopic visual sensitivity function V′λ, and a chromaticity calculator connected to the photodetectors. A correction coefficient c calculator connected to the chromaticity calculator, a correction coefficient c calculator, an L _bp calculator connected to the photoreceiver, and an L _bs calculator connected to the V′λ photoreceiver. , The limited part connected to the L _bp calculation part and the L _bs calculation part, and the limited part and L
_bp calculator, composed of a adaptation coefficient a calculation unit which is connected to either the L _bs calculating unit, the L _bp calculator, and L _bs calculator and L _bm calculation unit connected to the adaptation coefficient a calculator This is a photometric device that calculates the adaptation coefficient a with a small memory capacity based on the relationship between the L _bs value and the L _bp value of the color light that normally exists, and measures the equivalent luminance in mesopic vision.

As for the second problem, in the mesopic vision region, the adaptation coefficient a is used with a certain accuracy in the table memory regardless of the magnitude of the photopic equivalent luminance L _bp and the scotopic equivalent luminance L _bs. It is an object of the present invention to provide a photometric device that improves the measurement accuracy of mesopic equivalent luminance for colored light.

The present invention provides a color matching function, and a scotopic visibility function V ′.
4 types of light receivers with spectral sensitivity corresponding to λ,
A chromaticity calculation unit connected to the photodetector, a correction coefficient c calculation unit connected to the chromaticity calculation unit, a correction coefficient c calculation unit, an L _bp calculation unit connected to the photodetector, and the V ′ and λ light receiver connected to the L _bs calculator, a comparator circuit connected to the L _bp calculator and L _bs calculator, the adaptation coefficient a calculation unit which is connected to the L _bp calculator and L _bs calculator, A photometric device composed of an adaptation coefficient a calculation unit, an L _bp calculation unit, and an L _bm calculation unit connected to the L _bs calculation unit, and is related to the magnitude relationship between the L _bp value and the L _bs value obtained by measurement. Adaptation coefficient a
Is calculated with a certain accuracy, and the mesopic equivalent luminance is accurately measured with respect to various kinds of color light using this a.

Action In the solution to the first problem of the present invention, in the mesopic vision region, with reference to one of the measured values of L _bp or L _bs , the normal range of L that can take the effective range of the other measured value. Limited L based on the relationship between _bp and L _bs value
_The adaptation coefficient a is read from the memory by inputting the measured value (limited value) of _bp or L _bs and the measured value (reference value) which is not limited. Furthermore, this adaptation coefficient a and L _bp or L _bs
Equivalent brightness L _bm in mesopic based on limit value and the reference value of
Ask for.

In the solution to the second problem of the present invention, the comparison circuit obtains the magnitude relationship between the photopic equivalent luminance value L _bp and the scotopic equivalent luminance value L _bs . The result of the comparison circuit is supplied to the adaptation coefficient a calculation unit, and the coding resolution of L _bp or L _bs is changed according to the difference between the L _bp value and the L _bs value, or L _bp and L _bs are compared. A plurality of adaptation coefficient a table memories having a function of the adaptation coefficient a corresponding to the difference are selected to keep the calculation accuracy of the adaptation coefficient a constant.

Embodiment An embodiment of the present invention will be shown below as a means for solving the first problem. In FIG. 1, 1 is a light receiver, 2 is a light receiver, 3 is a light receiver, 4 is a V′λ light receiver, 5 is a chromaticity calculation unit, 6 is a correction coefficient c calculation unit, 7 is an L _bp calculation unit, 8 is L
_bs calculation unit, 9 _Lbs limited unit, 10 adaptation coefficient a calculation unit, 1
1 is an L _bm calculation unit. FIG. 1 shows an example of limiting the range that L _bs can take in L _bp . In FIG.
The configurations and operations of the photoreceiver 1, the photoreceiver 2, the photoreceiver 3, the V′λ photoreceiver 4, the chromaticity calculator 5, the correction coefficient c calculator 6, the L _bp calculator 7, and the L _bs calculator 8 are conventional. It is the same as the photometric device.

Further, the configuration and operation of the L _bm calculation unit 11 are also the same as the conventional one, and thus detailed description thereof will be omitted. FIG. 2 shows L _{bs in} FIG.
FIG. 9 is a concrete configuration diagram of the limiting unit 9 and the adaptation coefficient a calculating unit 10. 9a is an L _bs logarithmic conversion circuit, 9b is an L _bp logarithmic conversion circuit,
9c is a subtraction circuit, 10a is an _Lbs coding circuit, 10b is an _Lbp coding circuit, and 10c is an adaptation coefficient a calculation memory.

The operation of the photometric device of the present embodiment configured as described above will be described below. The L _bp calculation unit 7 outputs the equivalent luminance L _bp in photopic vision, and the L _bs calculation unit 8 outputs the equivalent luminance L _{bs in} scotopic vision. These are supplied to the L _bs limiting section 9. In the mesopic region, L _bp ≤ 14.1 cd / m ²
When the condition of _bs ≥ 0.003 cd / m ² is satisfied, the adaptation coefficient a is 0
Takes a value of 1. Therefore, the L _bs limiting unit 9 processes the L _bp value and the L _bs value by using the magnitude relationship established for the normal color light between the L _bs and the L _bp .

Usually, as a result of measuring the spectral distribution of color light existing under the visual environment, the spectral distribution characteristic of normal color light does not show a sudden change. L _bp and L _bs were calculated with respect to this measurement result, the relationship between them was calculated, and L _bp was represented as a reference, as shown in FIG. The horizontal axis shows the equivalent luminance values in Figure 3, the logarithmic value of the upper horizontal axis L _bs, lower row shows the logarithmic value of L _bs. The cross mark indicates composite light (color light that is present in a normal visual environment due to the combination of monochromatic lights), and the chromaticity of red, green, and blue is shown in FIG.
In addition, the mark ◯ shows the calculation result of monochromatic light of 400 nm to 700 nm, and similarly, the chromaticity of 400 nm, 570 nm and 700 nm is shown in FIG. Fig. 3 shows the result of fixing the measured value L _bpi of L _bp and _obtaining the measured value L _bsi of L _bs for it, where L _bpi > L _bsi is red light and L _bpi <L _bsi is blue light. Handle. An example will be described with reference to FIG. When L pairs _bpi numeric (log L _bpi) is assumed to be 0 in relative value, contrast range can take L _bsi is next _{P c1 ~P c2 ~P c3, -1.23} ≦ log L bs ≦ + 1.
It will be 11. Therefore, the L _bs logarithmic conversion circuit 9a in the L _bs limiting unit 9
The L _bp logarithmic conversion circuit 9b logarithmically converts the measured values of L _bs and L _bp , and the subtraction circuit 9c calculates the difference (ΔL) between the output of the L _bs logarithmic conversion circuit 9a and the output of the L _bp logarithmic conversion circuit 9b. . This difference is −1.
Only the difference ΔL ₁ and ΔL _{2 in the range of} 23 ≦ log L _bs ≦ + 1.11 is output from the subtraction circuit 9c. The outputs ΔL ₁ and ΔL ₂ of the subtraction circuit 9c are supplied to the adaptation coefficient a calculator 10, and ΔL ₁ or ΔL ₂ is
L _bs code is encoded in circuit, whereas L _bp measurements L _bp
It is coded by the coding circuit, and this output is input to the adaptation coefficient a calculation table memory 10 to read the adaptation coefficient a. The operation of the adaptation coefficient a calculation table memory is the same as in the case of the conventional photometric device, and the details are omitted.

FIG. 4 shows a map configuration of the calculation table memory of the adaptation coefficient a when the measurement range of log L _bp and log L _bs is set to 5 (change range of 10 ⁵ ) in relative value. In Figure 4, the horizontal axis is log L
The relative value of _bp is shown, and the vertical axis shows the relative value of log L _bs . In the part indicated by b in Fig. 4, log L _bs is log L _bp −1.23 ≦ log L.
_bs ≤ log L _bp ⁺ 1.11, which is log under normal combined light.
L _bp and log L _bs have a relationship within this area. The conventional photometric device has a memory for obtaining the adaptation coefficient a for a combination of changes of 5 in relative values of log L _bp and log L _bs . Assuming that the memory capacity required for a change of 1 in the relative values of log L _bp and log L _bs is N, a memory capacity of 36 N has been conventionally required. On the other hand, in the present invention, it suffices to have the adaptation coefficient a calculation memory only for the area B in FIG. In the present invention, for a change in relative value 1 of log L _bp , log L _bs is lo
Since the range is from g L _bp −1.2 to log L _bp +1.1, it is sufficient that the relative value is 2. Therefore, the adaptation coefficient a table memory 10c has a capacity of 9N, and the adaptation coefficient a with a memory capacity of 1/4.
Can be calculated.

FIG. 5 shows the map structure of the adaptation coefficient a table memory 10c of FIG. 4 centered on the relative value of log L _bp , and the area B corresponds to the area B of FIG. The blank portion shown in FIGS. 4 and 5 is the adaptation coefficient a table memory 10
In c, it is a portion that is not used for calculating the adaptation coefficient a for ordinary composite light, and in the conventional photometric device, there is a large blank portion as shown in FIG. On the other hand, in the present invention, the blank area is greatly reduced as shown in FIG.

On the other hand, for monochromatic light of 460 nm to 680 nm, log L _bs is P _{M1 to} P _{M2 to} P _M3 for log L _bp , as indicated by the circle in FIG.
And changes within the range of log L _bp −1.98 ≦ log L _bs ≦ log L _bp + 1.35, and other values are not taken. If the range of log L _bs that can be taken is set in this way for log L _bp , the capacity of the adaptation coefficient a table memory can be set to about 16 N in the case of monochromatic light, and the memory capacity is reduced to about 45% compared to the conventional one. Can be made.

In this embodiment, the range of L _bs is limited to L _bp and L _bp.
The method of converting _bs logarithmically and limiting it by the difference is L _bp and L
_The same applies when limited by the ratio of _bs . Also, L _bs is L _bp
It goes without saying that the method of limiting the same has the same effect.

As a means for solving the second problem, other embodiments of the present invention are shown in FIGS. In FIG. 6, 1 is a light receiver, 2 is a light receiver, 3 is a light receiver, 4 is a V′λ light receiver, 5 is a chromaticity calculator, 6 is a correction coefficient C calculator, and 7 is L _bp.
A calculation unit, 8 is an L _bs calculation unit, 12 is a comparison circuit, 13 is an adaptation coefficient a calculation unit, and 11 is an L _bm calculation unit. In FIG.
The configurations and operations of the photoreceiver 1, the photoreceiver 2, the photoreceiver 3, the V′λ photoreceiver 4, the chromaticity calculator 5, the correction coefficient c calculator 6, the L _bp calculator 7, and the L _bs calculator 8 are conventional. It is the same as the photometric device. Further, the configuration and operation of the L _bm calculation unit 11 are also the same as the conventional one, and thus detailed description thereof will be omitted. FIG. 2 shows a first embodiment of the adaptation coefficient a calculation unit 13, where 13a is L
_bs coding circuit, 13b is an _Lbp coding circuit, and 13c is an adaptation coefficient a table memory.

Regarding the photometric device of the present embodiment configured as described above,
The operation will be described below.

The photopic equivalent luminance L _bp is output from the L _bp calculation unit 7, and L _bs
The calculation unit 8 outputs the scotopic equivalent luminance L _bs . These are supplied to the comparison circuit 12 to take the difference between the two. Comparison circuit
The output of 12 is supplied to the adaptation coefficient a calculator 13 to obtain the adaptation coefficient a. The operations of the comparison circuit 12 and the adaptation coefficient a calculator 13 will be described with reference to FIG. 8 based on an embodiment with L _bp as a reference.

The comparator circuit 12 _{calculates ΔL bs} (= L _bp −L _bs ). Output △ L _bs comparison circuit 12, L _bs together with the output of the L _bs calculator 8
It is supplied to the encoding circuit 13a. In L _bs coding circuit 13a, △ by the magnitude of the numerical value of L _bs, to determine the possible values of L _bs, encoding L _bs. The principle of encoding L _bs and calculating the adaptation coefficient a will be described with reference to FIG. In FIG. 8, the horizontal axis represents the equivalent luminance L _b , and the vertical axis represents the adaptation coefficient a. The thick line in FIG. 8 shows the relationship between the equivalent luminance L _b and the adaptation coefficient a. (A =
ai) Also, the thin line is a straight line showing the relationship of log L _bm = a log L _bs + (1-a) log L _bp , and the adaptation coefficient a to be obtained from the reading on the vertical axis at the intersection of these two functions is Represent. In Figure 8
When the log-transformed value L _bpi of the measured value of L _bp and the log-transformed value L _bsi of the measured value of L _bs become equal, the value on the vertical axis of the intersection P ₀ is the adaptation coefficient a to be obtained. When the value of L _bsi changes by _{ΔL bs} with respect to the value of L _bpi and becomes L _{bs (i-1)} (= L _bsi − △ L _bs ), the intersection point is P
_(i-1) , the adaptation coefficient a becomes a _(i-1) , and a value obtained by changing the value a _i of the adaptation coefficient a having the same precision by Δa ₁ (= a _(i-1) −a _i ). To take. On the other hand, when L _{bs (i + 1)} (= L _bsi + _{ΔL bs} ), the intersection is P _{(i + 1)} , the adaptation coefficient a is a _{(i + 1)} , and the deviation from a _i is Δa ₂ (= a _i −a _{(i + 1)} ). As is clear from FIG. 8, since the value of the adaptation coefficient a is a curve having a negative slope, _{Δa 1} > _{Δa 2} and L _bsi is the same amount ( _{ΔL bs} ).
Despite the change, the adaptation coefficient a does not have the same amount of change. That is, the change amount of a becomes larger in L _{bs (i-1)} .

Therefore, when the L _bs value is smaller than the L _bp value, the change amount of L _bsi is
(In this case, it corresponds to the case of measuring red light)
Is a value less than _{ΔL bs, ΔL bs1,} and
Conversely, when the L _bs value is larger than the L _bp value (in this case, when blue light is measured), a value larger than _{ΔL bs ΔL}
Determine the operation of the L _bp coding circuit to take _bs2 . Specifically, it can be realized by providing a plurality of coding tables having different resolutions of L _bs and selecting a necessary coding table according to the magnitude of the value of _{ΔL bs} . As a result, the L _bsi values are L' _{bs (i-1)} and L' _{bs (i + 1)} , and the intersection points are P ' _(i-1) ,
P ' _{(i + 1)} , the adaptation coefficient a becomes a' _(i-1) , a ' _{(i + 1)} , and a
Δa (= a _(i-1) −a _i = a _i −a _{(i + 1)} )
Can be equal to Thus, the variation range of the adaptation coefficient a increases in proportion to the difference △ L _bs of L _bp and L _bs.
Therefore, the output value ΔL _bs of the comparison circuit 12 may be set so that the resolution of L _bs is inversely proportional.

On the other hand, the L _bp coding circuit 13b _equally decomposes the output value L _bp from the L _bp calculator 7 and codes it. Further, the output of the L _bs coding circuit 13a and the output of the L _bp coding circuit 13b are supplied to the adaptation coefficient a table memory, and a is obtained according to the curve of the adaptation coefficient a shown in FIG.

Thus, by the magnitude of the difference △ L _bs of L _bp and L _bs, it is possible to change the resolution at the time of encoding the L _bs, L _bp and L _bs
Even for colored lights with different values, using the table memory,
The adaptation coefficient a can be calculated with the same accuracy.

In the above example, L _bp was used as the reference, but the same effect can be obtained using L _bs as the reference.

FIG. 9 shows another embodiment of the adaptation coefficient a calculator 13.
In FIG. 9, 13d is L _bs coding circuit, 13e is L _bp coding circuit, 13f ₁ ~13f _n is the n adaptation coefficients a _n table memory, 13
g is an adaptation coefficient a selection part. As shown in FIG. 10, the n pieces of adaptation coefficient a table memories each have independent functions of equivalent luminance and adaptation coefficient. Functions like adaptation coefficient a ₁ table memory 13f ₁ are indicated by a _1, adaptation coefficient a ₂ table memory 13f ₂ is a _2, adaptation coefficient a _n table memory 13f _n has a function shown by a _n. a ₁ ~a _n, as shown in FIG. 10, a ₁
Set the value of the adaptation coefficient a is reduced for the same equivalent brightness according becomes a _n from the difference of these functions is determined by the difference △ L _bs of L _bp and L _bs. △ L _bs (= L _bp −L _bs )
Is a positive number and its absolute value becomes large, the resolution of the adaptation coefficient a with respect to changes in L _bs decreases. Therefore, the functions a _{2 to} a _n in FIG. 10 are adapted in proportion to the magnitude of the _{ΔL bs} value. Coefficient a selector
Select with 13g. As a result, the amount of change in a with respect to _{ΔL bs} can be reduced. Further, the theoretical function a ₁ is selected in the vicinity of _{ΔL bs} becoming zero. Further, when ΔL _bs has a negative polarity and a large absolute value, the resolution of the adaptation coefficient a is improved in the function a ₁ , so the resolution is lowered. Therefore, depending on the magnitude of the absolute value of _{ΔL bs} , as shown in FIG. The function a _{2 to} a _{n of} is selected to obtain the adaptation coefficient a.

In a second embodiment of the present invention, △ L includes n adaptation coefficients a table memory corresponding to _bs, △ by the size of L _bs, to determine the table to be selected, the measurement difference between the L _bp and L _bs It is possible to make the calculation accuracy of the adaptation coefficient a constant regardless of

Although the second embodiment has been described based on L _bp , the same effect can be obtained by using L _bs as a reference. In this case, the relationship between the difference between L _bp and L _bs and the selected adaptation coefficient a table memory may be reversed.

As described above, if the adaptation coefficient a is accurately calculated for various color lights, it is clear that the _mesopic equivalent luminance L _bm can be accurately calculated without being affected by the color light.

EFFECTS OF THE INVENTION The photometric device of the present invention with respect to the first problem is connected to an L _bp calculation unit that obtains an equivalent luminance in a photopic region and an L _bs calculation unit that obtains an equivalent luminance in a scotopic region. _bp
A _limiter that limits the range that the other value can take with reference to one of the output values of the calculator and the L _bs calculator;
_An adaptation coefficient a table memory is provided by providing an adaptation coefficient a calculation section for calculating an adaptation coefficient a in mesopic vision by connecting the calculation section that is not limited to the outputs of the _bp calculation section and the L _bs calculation section and the limitation section. With a small capacity, the adaptation coefficient a can be obtained for normal color light, and its practical effect is great.

The photometric device of the present invention for the second problem is
A comparator circuit for comparing the measurement values of the L _bs of L _bp, by providing the adaptation coefficient a calculation of the table memory method of controlling the adaptation coefficient a calculated by the output of the comparator circuit, L _bp by measurement target color light Even if the measured values of L _bs and L _bs change and the magnitude relation changes, the calculation accuracy of the adaptation coefficient a can be changed, and its practical effect is large.

[Brief description of drawings]

FIG. 1 is a block diagram of a photometric device in an embodiment of the present invention of a first solving means, and FIG. 2 is a concrete configuration of an L _bs limiting section and an adaptation coefficient a calculating section in an embodiment of the first solving means. Figure,
FIG. 3 is a diagram relatively expressing the result of the relation between L _bp and L _bs of ordinary combined light and monochromatic light as log L _bp = 0.
FIG. 5 is a diagram showing a configuration of an adaptation coefficient a table memory of a conventional photometric device, FIG. 5 is a diagram showing a configuration of an adaptation coefficient a table memory of the present invention, and FIG. 6 is a second solving means of the present invention. FIG. 7 is a configuration diagram of a measuring apparatus in the embodiment, FIG. 7 is a concrete configuration diagram of an adaptation coefficient a calculating unit in the first embodiment of the second solving means, and FIG. 8 is a first configuration of the second solving means. FIG. 9 is a diagram showing the operating principle of the adaptation coefficient a calculator in the embodiment, FIG. 9 is a concrete configuration diagram of the adaptation coefficient a in another embodiment of the second solving means, and FIG. 10 is a drawing of the second solving means. FIG. 11 is a diagram showing the relationship between the equivalent luminance of a plurality of adaptation coefficient a table memories and the adaptation coefficient in another embodiment, FIG. 11 is a configuration diagram of a conventional photometric device, and FIG. 12 is a specific configuration diagram of a light receiver. FIG. 13 is a specific configuration diagram of the correction coefficient c calculation unit, and FIG. 14 is a specific configuration diagram of the adaptation coefficient a calculation unit, FIG. 15 is a specific configuration diagram of the L _bm calculation unit, FIG. 16 is a diagram showing the relationship between the adaptation coefficient a and the equivalent luminance, and FIG. 17 is the calculation of the adaptation coefficient a when the adaptation coefficient a table memory is used. FIG. 18 is a diagram showing a method, and FIG. 18 is a diagram showing relative sensitivities of four types of light receivers. 7 ... L _bp calculation unit, 8 ... L _bs calculation unit, 9 ... L _bs limiting unit, 10 ... adaptation coefficient a calculation unit, 11 ... L _bm calculation unit, 12
...... Comparison circuit, 13 Adaptation coefficient a calculation unit, 14 Adaptation coefficient a calculation unit, 9a …… L _bs logarithmic conversion circuit, 9b …… L _bp logarithmic conversion circuit, 9c …… Subtraction circuit, 10a, 13a , 13d …… L _bs coding circuit, 10b, 13b, 13e …… L _bp coding circuit, 10c, 13c
...... adaptation coefficient a table _{memory, 13f 1, 13f 2, 13f} n ...... adaptation coefficient a _n table memory, 13 g ...... adaptation coefficient a selection unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiro Arai 1-1-4 East, Tsukuba-shi, Ibaraki Institute of Industrial Science and Technology, Institute of Industrial Science (72) Inventor Shigeru Horii 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshiharu Osaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideo Nishiyama, 1006 Kadoma, Kadoma City, Osaka Prefecture Inspector Yoshinori Hirai (56) References Sagawa, K .; and Takei chi, K .; , Mesopic photometry system based on brightness perc eption, CIE 21st Session P.P. 30-33, 1987. Models of Heterochromatic Brightness Matching, CIE-journal 5 [2] P. 57-59, 1986.

Claims (7)

[Claims] 1. Four types of light receivers having a color matching function, and a scotopic visibility function V′λ of spectral sensitivity, and
Also, a chromaticity calculation unit connected to the light receiver, a correction coefficient c calculation unit connected to the chromaticity calculation unit for obtaining a coefficient depending on the color of the brightness perceived by humans, the correction coefficient c calculation unit and the light receiver. Is connected to the V b λ photodetector, and an L _bP calculator for _{obtaining the} equivalent luminance in the photopic region.
L _bS calculation unit for _{obtaining the} equivalent luminance in the scotopic region, connected to the L _bP calculation unit and L _bS calculation unit, the limiting unit that limits the possible range of the other one of L _bP , L _bS An adaptation coefficient a calculation section that is connected to the calculation section for the signal that is not limited to L _bP and L _bS and the limitation section, and obtains an adaptation coefficient a according to this brightness level; an adaptation coefficient a calculation section; A photometric device connected to the L _bP calculation unit and the L _bS calculation unit, and configured to include an L _bm calculation unit that obtains an equivalent luminance in the _mesopic region based on log L _bm = a log L _bS + (1-a) log L _bP . 2. The adaptation coefficient a calculation unit is L _bP ≦ 14.1 cd / m ² ,
The photometric device according to claim 1, wherein the photometric device operates for L _bS ≧ 0.003 cd / m ² and has a function of limiting the range that can be taken by the ratio of L _bS and L _bP . 3. The limiting part and the ratio of L _bP to L _bS are +1 in logarithmic value.
The photometric device according to claim 2, wherein the compound light is in the range of 11 to -1.23. 4. The ratio of L _bP to L _{bS in} the limited part is logarithmically +1.35.
3. A photometric device according to claim 2, for monochromatic light within the range of -1.98. 5. A light receiving device having four types of spectral sensitivity having a color matching function, and a scotopic visual sensitivity function V′λ, and
Also, a chromaticity calculation unit connected to the light receiver, a correction coefficient c calculation unit connected to the chromaticity calculation unit, for obtaining a coefficient depending on the color of the brightness perceived by humans, a correction coefficient c calculation unit, and the light receiver. L _bP calculation unit connected to the L _bP calculation unit for _obtaining an equivalent luminance L _bP in the photopic region, and an L _bS calculation unit connected to the V′λ optical receiver for obtaining an equivalent luminance L _bS in the scotopic region; connected to _bP calculator and L _bS calculator receives a comparison circuit for determining the magnitude relation between L _bP and L _bS, the output of the L _bP calculator and L _bS calculator, tables difference L _bP and L _bS It is connected to the adaptation coefficient a calculation unit that _keeps the calculation accuracy of the adaptation coefficient a read from the memory constant, the adaptation coefficient a calculation unit, the L _bP calculation unit, and the L _bS calculation unit, and log L _bm = a log L _bS + ( 1-a) log L _bP the basis equivalent brightness in mesopic region (L _bm) photometric apparatus composed of a L _bm calculator for obtaining the 6. An adaptation coefficient a calculation unit, an L _bP or L _bS coding circuit connected to a comparison circuit, an L _bP or L _bS coding circuit not connected to the comparison circuit, and these two codes. An adaptation coefficient a table memory connected to a coding circuit, and having a function of varying the resolution at the time of coding according to the magnitude of the output value of the comparison circuit.
The photometric device described. 7. An adaptation coefficient a calculation unit includes a plurality of L _bP coding circuits, L _bS coding circuits, and a plurality of L _bP coding circuits connected to these two coding circuits and corresponding to a difference between the L _bP value and the L _bs value. Of the adaptation coefficient a table memory, a plurality of adaptation coefficient a table memories, and an adaptation coefficient a selection section connected to the comparison circuit, and the adaptation coefficient a table memory to be used depending on the size of the output value of the comparison circuit. The photometric device according to claim 5, wherein