JP3639701B2 - Measuring device, light source characteristic value calculating device and calculating method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measuring apparatus that measures , for example, the color temperature, illuminance (luminance), and color rendering of incident light .
[0002]
[Prior art]
In an object that reflects light from a light source included in illumination (hereinafter referred to as a reflective object), the color of the reflected object is reflected by the reflection of the light from the light source, and the reflective object is illuminated. Varies depending on the characteristics of the light source. Therefore, in order to display a reflective object with a similar color appearance on a monitor when it is input with a scanner or photographed with a digital camera, for example, the characteristics of the light source that illuminates the reflective object In particular, it is necessary to calculate color temperature, illuminance, and color rendering properties, and to perform color correction using these data. Here, the color rendering property is one of indices indicating the performance of the artificial light source, and represents the performance that can express the color of an object with a color close to the state seen with natural light.
[0003]
In addition, in order to perform color correction so that the appearance of the color of the reflecting object becomes a desired appearance regardless of the light source of the illumination, the characteristics of the light source that illuminates the reflecting object, particularly color temperature, illuminance (luminance) ) And color rendering properties are required to be measured with high accuracy.
[0004]
[Problems to be solved by the invention]
As a method for measuring the color temperature and illuminance of a light source with high accuracy, for example, a method using an illuminometer, a color luminance meter, or a spectral radiance (illuminance) meter has been proposed. For example, for the color temperature, there is a measuring device using a method according to 'JIS Z 8725-1987; Method for measuring distribution temperature and color temperature / correlated color temperature of light source', and the color temperature and illuminance (luminance) of the light source. Can be measured easily. That is, for measuring illuminance (luminance), the spectral colorimetric value is multiplied by the standard relative luminous sensitivity (new edition Color Science Handbook; see the University of Tokyo Press), or the spectral sensitivity characteristic similar to the standard relative luminous sensitivity. A general method is to use a sensor having As for the measurement of the color temperature, basically, a method of performing spectral colorimetry or a method of obtaining using three types of sensors having different spectral sensitivity distributions is generally used.
[0005]
However, in the method using three types of sensors having different spectral sensitivity distributions, there are cases where there are light sources having different color rendering properties even if the color temperature is the same. It is difficult to obtain the color rendering property at the same time as it is held.
[0006]
The definition of color rendering properties is clearly shown in 'JIS Z 8726-1990; Color rendering property evaluation method of light source'. However, depending on the method, measurement of spectral distribution data and complicated calculation processing using the measurement data are required, and this is not easily obtained.
[0007]
Thus, it is difficult to obtain the color temperature, illuminance (luminance), and color rendering properties of the light source at the same time and with high accuracy.
[0008]
Further, in the environment where the reflection object is observed, a light source in which color rendering is an important characteristic value is, for example, a fluorescent lamp, and an apparatus for detecting whether the light source is a fluorescent light source such as a fluorescent lamp has been proposed. . In addition, a light source that detects flicker of a light source (Japanese Patent Laid-Open No. 61-240790) and a device that detects a peak of an energy spectrum at a specific wavelength (Japanese Patent Publication No. 7-58226) have been proposed.
[0009]
However, color rendering varies depending on the type of fluorescent light source, and color rendering varies depending on the mixing ratio as in the case of illumination light obtained by mixing natural light and fluorescent light source. It is difficult to obtain the color rendering properties of the light source only by detecting whether it is a light source.
[0010]
Accordingly, the present invention provides a measuring apparatus that measures the color temperature, illuminance (luminance), and color rendering of light incident from a light source with high accuracy.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the measuring apparatus of the present invention is characterized by the following configuration.
[0012]
That is, a measuring device that measures the color temperature, illuminance (luminance), and color rendering properties of incident light, the first, second, and third light detection units having spectral sensitivity characteristics that satisfy a router condition; Incident light using a fourth light detection unit having spectral sensitivity characteristics different from those of the first, second, and third light detection units, and output values of the first to fourth light detection units. Color temperature, illuminance (luminance) and color rendering
X = a11 × A + a12 × B + a13 × C + a14 × D + a15
Y = a21 * A + a22 * B + a23 * C + a24 * D + a25
Z = a31 * A + a32 * B + a33 * C + a34 * D + a35
X: color temperature, Y: illuminance (luminance), Z: color rendering, A: output value of the first photodetection unit, B: output value of the second photodetection unit, C: of the third photodetection unit An output value, D: an output value of the fourth light detection unit, and a light source characteristic calculation unit calculated using an arithmetic expression expressed by a11 to a35: calculation coefficients, and the first light detection unit Has a spectral sensitivity characteristic peak in the range of 520 nm to 580 nm, the second photodetection section has a spectral sensitivity characteristic peak on the wavelength side shorter than 520 nm, and the third photodetection section has a spectral sensitivity The characteristic peak is in the range of 570 nm to 650 nm, and the fourth photodetecting portion is characterized in that the spectral sensitivity characteristic peak is in the range of 600 nm to 680 nm .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a light source characteristic value calculation apparatus according to the present invention will be described in detail in a first embodiment, and a light source characteristic measurement apparatus in a second embodiment, with reference to the drawings.
[0018]
[First Embodiment]
Hereinafter, in the first embodiment of the present invention, a light source characteristic value calculation device that calculates and outputs values representing color temperature, illuminance (luminance), and color rendering properties as light source characteristic values of an illumination light source will be described. To do.
[0019]
FIG. 1 is a block configuration diagram of a light source characteristic value calculation apparatus according to a first embodiment of the present invention.
[0020]
In the figure, the light source characteristic value calculation device 1 includes a light detection unit 10 and an arithmetic processing unit 20. The light detection unit 10 includes four light detection units 10a to 10d, and outputs output signals (voltages) V10a to V10d according to the amount of incident light 30 according to the spectral sensitivity characteristics of each light detection unit. .
[0021]
Further, the arithmetic processing unit 20 uses the voltages V10a to V10d output from the four photodetection units having different spectral sensitivity characteristics, and the color temperature (CCT), luminance (KD), and color rendering property coefficient (FLC) of the incident light 30. Is calculated and output by a method described later. The arithmetic processing unit 20 includes a CPU 21, a RAM 22, and a ROM 23, and the CPU 21 controls the arithmetic processing unit 20 according to a program stored in advance in the ROM 23.
[0022]
FIG. 2 is a diagram showing an internal configuration of the light detection unit according to the first embodiment of the present invention. The four light detection units (10a to 10d) have the same structure, but hereinafter, the light detection unit 10a. Will be described as an example.
[0023]
In the figure, the light detection unit 10a includes a filter 101a, a light receiving diode 102a that receives incident light 30 through the filter 101a, and an operational amplifier 103a that amplifies the output voltage of the light receiving diode 102a. The spectral sensitivity characteristics of the light detection unit 10a are defined by the characteristics of the filter 101a and the light receiving diode 102a.
[0024]
The light detection unit 10a includes a variable resistor 104a, and the output voltage of the light receiving diode 102a can be adjusted by changing the resistance value of the variable resistor 104a.
[0025]
4 to 6 are diagrams showing spectral intensity distributions of various light sources as the first embodiment of the present invention. Here, paying attention to the amount of light included in a wavelength range longer than about 600 nm, in FIG. 5, f * a indicates the spectral intensity distribution of a light source with low color rendering properties (* is d, n, w). In FIG. 4, f * 3a indicates a spectral intensity distribution of a light source having higher color rendering than in FIG. 5 (* is d, l, n, w). In FIG. 6, fn3r represents the spectral intensity distribution of a light source having higher color rendering properties than that of FIG.
[0026]
Also, in each figure, focusing on the light quantity included in the wavelength range longer than about 600 nm out of the total quantity of incident light (area formed by the spectral intensity distribution curve and the horizontal axis of each light source), the color rendering of each figure There is a correlation between sex.
[0027]
Next, how to adopt the spectral sensitivity characteristics of the four light detection units (10a to 10d) when the spectral intensity distribution characteristics of various light sources are shown in FIGS. 4 to 6 will be described with reference to FIG.
[0028]
FIG. 3 is a diagram showing the spectral sensitivity characteristics of the light detection unit according to the first embodiment of the present invention, and shows a relative output value with respect to the wavelength of incident light. Here, the relative output value represents the ratio between the output voltage of the light detection unit for incident light having a predetermined wavelength and the output voltage for other wavelengths.
[0029]
In the figure, the spectral sensitivity characteristic of the light detection unit 10a corresponds to 300a, the spectral sensitivity characteristic of the light detection unit 10b corresponds to 300b, the spectral sensitivity characteristic of the light detection unit 10c corresponds to 300c, and the light detection unit The spectral sensitivity characteristic of 10d corresponds to 300d.
[0030]
In order to calculate the color temperature and illuminance (luminance) with high accuracy, it is necessary to sufficiently satisfy the conditions of the router as described in 'JIS Z 8724-1983; Measuring method of light source color'. is there. Therefore, since it is necessary to design the spectral sensitivity characteristics of the light detection unit so as to satisfy the conditions, the degree of design freedom is limited. Therefore, for the light detection units 10a to 10c, in this embodiment, the spectral sensitivity characteristic 300a of the light detection unit 10a has a spectral sensitivity characteristic in which the main spectral sensitivity peak is between 520 nm and 580 nm. The spectral sensitivity characteristic 300b of the light detection unit 10b has a spectral sensitivity characteristic in which the main spectral sensitivity peak is on the shorter wavelength side than 520 nm. The spectral sensitivity characteristic 300c of the light detection unit 10c has a spectral sensitivity characteristic in which the main spectral sensitivity peak is on the wavelength side longer than 580 nm, and the main sensitivity is between about 570 nm and 650 nm.
[0031]
The brightness (illuminance) can be clearly determined according to the spectral intensity distributions of various light sources, without depending on the relative shapes of the spectral intensity distributions of various light sources, when the router condition is sufficiently satisfied in each light detection unit. .
[0032]
However, it is generally known that it is difficult to obtain the color rendering properties with high accuracy by using the correlation between the color rendering properties and the amount of light with only the light detection units 10a to 10c.
[0033]
Therefore, in this embodiment, a light detection unit 10d is further provided to calculate the color temperature, illuminance (luminance), and color rendering with high accuracy. The spectral sensitivity characteristic 300d of the light detection unit 10d is a spectral sensitivity characteristic different from the spectral sensitivity characteristic 300c of the light detection unit 10c, and is a spectral sensitivity characteristic whose main spectral sensitivity peak is on the wavelength side longer than 580 nm. Its spectral sensitivity was set to a spectral sensitivity characteristic whose wavelength is between 600 nm and 680 nm. The spectral sensitivity characteristics of the light detection unit 10d were obtained through simulations and experiments so as to obtain optimum characteristics for the various light sources shown in FIGS. By setting the sensitivity characteristics of the light detection unit 10d as described above, for example, a light source (fn3r shown in FIG. 6), such as a three-wavelength light-emitting fluorescent lamp having a different spectral intensity distribution tendency than a conventional fluorescent lamp. The color rendering properties can be calculated with high accuracy.
[0034]
Each light detection unit outputs voltages (V10a to V10d) corresponding to the spectral sensitivity characteristics shown in FIG. 3 for the amount of incident light 30, and the output voltage is input to the arithmetic processing unit 20. The arithmetic processing unit 20 calculates a color temperature (CCT), a luminance (KD), and a color rendering property coefficient (FLC) by the following formulas based on the input output signal voltage.
[0035]
CCT = a11 * V10a + a12 * V10b + a13 * V10c + a14 * V10d + a15 (1)
KD = a21 * V10a + a22 * V10b + a23 * V10c + a24 * V10d + a25 (2)
FLC = a31 × V10a + a32 × V10b + a33 × V10c + a34 × V10d + a35 (3)
Here, FIG. 7 is a diagram showing the coefficients (a11 to a35) used in the arithmetic processing unit as the first embodiment of the present invention. In the case where each light detection unit has a certain amplification factor, equation (1) is shown. To (3) are coefficients for calculating the color temperature (CCT), luminance (KD), and color rendering coefficient (FLC) with the highest accuracy. Therefore, it goes without saying that if the setting of the light detection unit is changed, the coefficient needs to be changed.
[0036]
FIG. 8 is a diagram showing output signal voltages of the respective light detection units due to incident light from various light sources as the first embodiment of the present invention.
[0037]
The arithmetic circuit 20 uses the coefficients (a11 to a35) and the output signal voltages (V10a to V10d) from the respective light detection units to calculate the color temperature (CCT) by the above-described expressions (1) to (3). Outputs luminance (KD) and color rendering coefficient (FLC).
[0038]
FIG. 9 is a diagram showing catalog values and calculated values of the color temperature and the color rendering coefficient for the various light sources shown in FIGS. 4 to 6 as the first embodiment of the present invention. In the figure, a color temperature and a color rendering property coefficient are shown as an example. The color temperature and color rendering coefficient in the catalog value column are catalog specifications of various light sources obtained by the method described in the above-mentioned JIS. The color temperature and the color rendering property coefficient in the calculated value column were calculated by the above formulas (1) and (3). Comparing the calculated values shown in FIG. 7 with the catalog values, it can be seen that the color temperature and the color rendering properties are calculated with high accuracy while the method according to the present embodiment is easy.
[0039]
In addition, although the calculation performed by the calculation processing unit 20 has been described by taking a linear calculation as an example, the calculation may be nonlinear. In particular, the non-linear processing is effective when the spectral sensitivity characteristics of each light detection unit cannot sufficiently satisfy the router condition.
[0040]
In addition, each light source characteristic value obtained by the calculation device according to the present embodiment is input to, for example, a device proposed by Japanese Patent Application No. 9-198341 preceded by the applicant of the present application, and is a light source that illuminates a reflector. Regardless of the type, it may be used for color correction processing for obtaining a desired color appearance with respect to the reflector.
[0041]
[Second Embodiment]
In the above-described first embodiment, the light source characteristic value calculation device 1 includes the arithmetic processing unit 20 and uses the output values of the respective light detection units 10a to 10d to calculate the color temperature (CCT), the luminance (KD), and the like. Although the color rendering property coefficient (FLC) is output as the light source characteristic, each light source characteristic value may be calculated by an external device as in the present embodiment.
[0042]
FIG. 10 is a block diagram of a light source characteristic measuring apparatus as the second embodiment of the present invention.
[0043]
In the figure, the light source characteristic measuring apparatus 1 </ b> A includes a light detection unit 10 and an analog / digital (A / D) conversion unit 40. The light detection unit 10 includes four light detection units (10a to 10d), and the description of each light detection unit is omitted because it is the same as that of the first embodiment. The A / D converter 40 includes A / D converters 40a to 40d that convert the output voltages V10a to V10d from the respective light detection units into digital data and output the digital data.
[0044]
The digital data output from the A / D conversion unit 40 is input to the arithmetic processing unit 2 separately provided outside the light source characteristic measuring apparatus 1A. The arithmetic processing unit 2 uses the digitized output data from each light detection unit to calculate the color temperature (CCT), luminance (KD), and color rendering property coefficient (FLC), as in the first embodiment. Calculate. Needless to say, the arithmetic processing unit 2 may be provided in, for example, a software module that performs color correction processing by the apparatus previously proposed by the applicant of the present application.
[0045]
In each of the embodiments described above, the characteristics of the light source to be calculated are the color temperature, the luminance (illuminance), and the color rendering coefficient, but are not limited thereto. For example, the tristimulus value and the color rendering coefficient Alternatively, it is possible to calculate a chromaticity value, luminance (illuminance), color rendering property coefficient, and the like.
[0046]
[Other Embodiments]
Note that the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or a device (for example, a copier, a facsimile device, etc.) composed of a single device. You may apply to.
[0047]
Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus. Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium.
[0048]
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.
[0049]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0050]
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) or the like running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0051]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0052]
As described above, according to the present invention, so that the color temperature of light incident from the light source, the illuminance (luminance) and color rendering properties it is possible to provide a measuring device for measuring with high accuracy.
[0053]
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a light source characteristic value calculation apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an internal configuration of a light detection unit as a first embodiment of the present invention.
FIG. 3 is a diagram showing spectral sensitivity characteristics of the light detection unit according to the first embodiment of the present invention.
FIG. 4 is a diagram showing spectral intensity distributions of various light sources as the first embodiment of the present invention.
FIG. 5 is a diagram showing spectral intensity distributions of various light sources as the first embodiment of the present invention.
FIG. 6 is a diagram showing spectral intensity distributions of various light sources as the first embodiment of the present invention.
FIG. 7 is a diagram illustrating coefficients (a11 to a35) used in the arithmetic processing unit according to the first embodiment of the present invention.
FIG. 8 is a diagram illustrating an output signal voltage of each light detection unit due to incident light from various light sources as the first embodiment of the present invention.
FIG. 9 is a diagram showing catalog values and calculated values of color temperature and color rendering coefficient for various light sources shown in FIGS. 4 to 6 as the first embodiment of the present invention.
FIG. 10 is a block configuration diagram of a light source characteristic measuring apparatus as a second embodiment of the present invention.

Claims (1)

A measuring device for measuring the color temperature, illuminance (luminance) and color rendering of incident light,
First, second, and third photodetectors having spectral sensitivity characteristics that satisfy the router condition;
A fourth light detection unit having spectral sensitivity characteristics different from the first, second, and third light detection units;
Using the output values of the first to fourth light detection units, the color temperature, illuminance (luminance), and color rendering of the incident light are expressed as follows:
X = a11 × A + a12 × B + a13 × C + a14 × D + a15
Y = a21 * A + a22 * B + a23 * C + a24 * D + a25
Z = a31 * A + a32 * B + a33 * C + a34 * D + a35
X: color temperature, Y: illuminance (luminance), Z: color rendering, A: output value of the first photodetection unit, B: output value of the second photodetection unit, C: of the third photodetection unit Output value, D: output value of the fourth light detection unit, a11 to a35: calculation coefficient,
A light source characteristic calculation unit that calculates using an arithmetic expression expressed by:
The first light detection unit has a spectral sensitivity characteristic peak in a range of 520 nm to 580 nm,
The second light detection unit has a spectral sensitivity characteristic peak on the wavelength side shorter than 520 nm,
The third light detection unit has a spectral sensitivity characteristic peak in a range of 570 nm to 650 nm,
The fourth photodetecting section has a spectral sensitivity characteristic peak in a range of 600 nm to 680 nm .

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