JP5529471B2 - Optical measuring device - Google Patents

Description

  The present invention relates to a measuring apparatus that measures the characteristics of a lighting fixture, for example, an apparatus that can measure illuminance and luminance.

  In order to improve the comfort and safety of night driving by a vehicle, a headlamp with good visibility is indispensable. In recent years, in addition to headlamps using conventional halogen light sources or HID (High Intensity Discharge) light sources, LED headlamps have been developed and adopted. In this way, at each stage where headlight light sources evolve from incandescent bulbs to halogen light sources, HID light sources, LED light sources, and high-efficiency light sources, developers and users realize a sense of improved road brightness and increased glare. I have done it.

  On the other hand, optical measuring apparatuses such as illuminance meters and luminance meters have been conventionally known for objectively evaluating the characteristics and performance of such various light sources (see, for example, Patent Documents 1 to 3).

JP 61-83920 A JP 62-90517 A JP 2006-177812 A

  However, in the development of the illumination light source as described above, even if the light amount measured by the conventional measuring device is the same, the psychological glare amount and the feeling of brightness differ depending on the difference in the spectral distribution of the illumination light source. It has become clear that there is a phenomenon.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for objectively measuring a feeling of psychological brightness.

  In order to solve the above-described problem, an optical measurement device according to an aspect of the present invention calculates the illuminance or luminance of incident light based on the standard relative luminous sensitivity and the S cone sensitivity.

  The optical measuring device according to another aspect of the present invention includes a light receiving unit that outputs a signal corresponding to the amount of received light, and a sensitivity characteristic for each wavelength at the light receiving unit that corresponds to the standard relative luminous sensitivity and S cone sensitivity. A sensitivity correction unit that selectively transmits incident light to the light receiving unit, and a calculation unit that calculates illuminance or luminance according to the output of the light receiving unit.

  According to these aspects, it is possible to objectively measure the feeling of brightness of the illumination light source including the wavelength component light that is the sensitivity region of the S cone by the same method as the conventional measurement of illuminance and luminance. . Thereby, the discrepancy between the sense of brightness actually felt by the observer and the measured value, which occurs when a specific light source is measured with a conventional measuring apparatus that supports only the standard relative luminous sensitivity, is reduced.

  The light receiving unit may include a first photoelectric conversion element and a second photoelectric conversion element. The sensitivity correction unit selectively transmits incident light to the first photoelectric conversion element so that the sensitivity characteristic for each wavelength of the first photoelectric conversion element is a sensitivity characteristic corresponding to the standard relative luminous sensitivity. Second optics for selectively transmitting incident light to the second photoelectric conversion element so that the sensitivity characteristic for each wavelength in the optical filter and the second photoelectric conversion element is a sensitivity characteristic corresponding to the S cone sensitivity. And a filter. The first photoelectric conversion element and the second photoelectric conversion element may each output a signal corresponding to the amount of received light. Thereby, an output according to the standard relative luminous sensitivity of the received light amount and an output according to the S cone sensitivity of the received light amount are obtained separately.

  The calculation unit calculates the illuminance or the luminance according to the output of the first photoelectric conversion element, and the calculation unit calculates the illuminance or the luminance according to the outputs of the first photoelectric conversion element and the second photoelectric conversion element. A switching unit that switches between the second calculation modes may be further provided. Thus, in addition to the mode for calculating the illuminance and the luminance according to only the standard relative luminous sensitivity, it is possible to easily switch to the mode for calculating the illuminance and the luminance according to the standard specific luminous sensitivity and the S cone sensitivity.

  A spectroscopic unit that outputs a signal corresponding to the amount of received light corresponding to each wavelength, a calculation unit that calculates a sensitivity curve according to the standard relative luminous sensitivity and the S cone sensitivity from the signal, and calculates illuminance or luminance according to the sensitivity curve , May be provided. Thereby, the discrepancy between the sense of brightness actually felt by the observer and the measured value, which occurs when a specific light source is measured with a conventional measuring apparatus that supports only the standard relative luminous sensitivity, is reduced.

  You may further provide the input part which inputs the coefficient which determines the ratio which the output of a 2nd photoelectric conversion element contributes to illumination intensity or a brightness | luminance in 2nd calculation mode. Thereby, it becomes possible to change the coefficient that determines the ratio that the output of the second photoelectric conversion element according to the S cone sensitivity contributes to the illuminance or the luminance by appropriately inputting from the input unit. Illuminance and brightness that correspond more accurately can be obtained.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to provide a technique for objectively measuring psychological brightness.

It is the figure which showed the graph of the spectral sensitivity function of each cone (S, M, L) with respect to a wavelength. It is the figure which showed the spectral distribution in each light source of LED, HID, and a halogen. It is a figure which shows the external appearance of the optical measuring device which concerns on 1st Embodiment. It is the figure which showed typically the element of the optical measuring device which concerns on 1st Embodiment. It is the figure which showed typically the element of the optical measuring device which concerns on 2nd this Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  The present inventor has a phenomenon that when an LED light source is used as a light source for a headlamp of an automobile, it feels brighter than when an HID light source or a halogen light source is used. The phenomenon that the brightness perceived by humans is different even though the measured values are adjusted to be the same is due to the effect of the S cone (a cell that feels blue) that is one of the cells of the human eye. I came up with something.

  Therefore, there is room for improvement in conventional illuminometers and luminance meters as devices for evaluating the brightness of LED light sources that have been adopted in many lighting devices, including automotive headlamps and household lighting fixtures. I came up with it.

FIG. 1 is a graph showing the spectral sensitivity function of each cone (S, M, L) versus wavelength. Conventionally, the illuminance and brightness for evaluating the brightness are based on the sensitivity characteristics SG (λ) and SR (λ) of the M cone (cells that feel green) and the L cone (cells that feel red) of the human eye. It is calculated | required and it is as showing in Formula (1).
Luminance L = KΣ ^380-780 S (λ) · p (λ) · V (λ) · dλ Expression (1)
K = 683lm / W
S (λ): Spectral radiance on the road surface p (λ): Spectral reflectance of the road surface V (λ) = M cone sensitivity SG (λ) + L cone sensitivity SR (λ): Standard relative luminous sensitivity curve

  As shown in Expression (1), the sensitivity characteristic SB (λ) of the S cone is not considered in the standard relative luminous sensitivity curve V (λ). Therefore, even if light having a wavelength having the sensitivity of the S cone is included in the light source, the measurement result of the luminance meter or the illuminometer hardly changes. Therefore, when an observer measures such a light source, there is a difference between the measurement value of the measuring device and the feeling of brightness felt by the observer.

  FIG. 2 is a diagram showing the spectral distribution of each LED, HID, and halogen light source. As shown in FIG. 2, it can be seen that the light from the LED light source has high radiance in the wavelength region (around 450 nm) where the sensitivity of the S cone is high. For this reason, in the LED light source, the difference between the measured value and the feeling of brightness is likely to occur.

  Therefore, the optical measurement apparatus according to the present embodiment is not only a conventional HID light source and halogen light source, but also an LED light source that is expected to be widely used in a wide range of illumination fields in the future, and the brightness feeling and measurement that an observer feels. The deviation from the value is reduced, enabling more objective measurement.

[First Embodiment]
(Optical measuring device)
FIG. 3 is a diagram illustrating an appearance of the optical measurement device according to the first embodiment. FIG. 4 is a diagram schematically showing elements of the optical measuring device according to the first embodiment. The optical measurement apparatus shown in FIGS. 3 and 4 will be described with an illuminometer as an example.

  As shown in FIG. 3, the illuminometer 10 includes a light receiving unit 12, a display unit 14, an input unit 16, a switch 18, a housing 20, and a milky white filter 22 that diffuses light emitted from the light source. Prepare. The light receiving unit 12 includes a first photosensor 24 and a second photosensor 26 as photoelectric conversion elements disposed below the milky white filter 22. As shown in FIG. 4, the received first photosensor 24 is configured so that a current corresponding to the amount of received light flows, and the current is converted into a voltage by the IV converter 28. Similarly, the received second photosensor 26 is configured such that a current corresponding to the amount of received light flows, and the current is converted into a voltage by the IV converter 30.

  The voltage signals converted by the respective IV converters are converted into digital signals by the A / D converters 32 and 34, and a predetermined calculation is performed by the calculation unit 36 constituted by a CPU or the like. That is, the calculation unit 36 calculates the illuminance according to the output of the light receiving unit 12. The result of the calculation is displayed on the display unit 14 including a liquid crystal display screen, for example, as a value indicating illuminance or brightness.

  Such an illuminometer 10 is required to have a light receiving portion having a sensitivity characteristic approximate to the standard relative luminous sensitivity V (λ) determined according to the sensitivity characteristic of the M cone and the sensitivity characteristic of the L cone. ing. Therefore, in the present embodiment, the first optical filter 38 is provided between the first photosensor 24 and the milky white filter 22. The spectral response characteristics realized by the first photosensor 24 and the first optical filter 38 are adjusted to match the standard relative luminous sensitivity V (λ). That is, the first optical filter 38 transmits incident light to the first photosensor 24 so that the sensitivity characteristic for each wavelength in the first photosensor 24 becomes a sensitivity curve corresponding to the standard relative luminous sensitivity V (λ). Selectively transmit. Here, the first optical filter 38 is a combination of a plurality of types of glass filters having different light transmittance characteristics.

  The light receiving unit configured as described above makes it possible to measure illuminance in accordance with standards such as conventional JIS and CIE standard color systems.

  On the other hand, in the illuminometer 10 according to the present embodiment, the second optical filter 40 is provided between the second photosensor 26 and the milky white filter 22. The spectral response characteristics realized by the second photosensor 26 and the second optical filter 40 are adjusted so as to correspond to the S cone sensitivity SB (λ). That is, the second optical filter 40 transmits incident light to the second photosensor 26 so that the sensitivity characteristic for each wavelength in the second photosensor 26 becomes a sensitivity curve corresponding to the S cone sensitivity SB (λ). Selectively transmit. Here, as the second optical filter 40, a combination of a plurality of types of glass filters having different light transmittance characteristics is used.

(Measuring method)
Next, a method for measuring illuminance by the illuminometer 10 according to the present embodiment will be described. When used as a normal illuminometer, the switch 18 is operated to select the first calculation mode for calculating the illuminance according to the output of the first photosensor 24. Of the light reflected by the headlamp light source on the road surface, light in a wavelength region corresponding to the standard relative luminous sensitivity V (λ) is incident on the first photosensor 24 by the first optical filter 38. The first photosensor 24 generates an electromotive current A1 in accordance with the amount of received light. The electromotive current A1 is converted by the IV converter 28, and further converted to the digital signal D1 by the A-D converter 32. 36. In the calculation unit 36, the illuminance Ak is calculated by the same processing as the above-described equation (1).

  On the other hand, when measuring a light source such as an LED light source that has a difference between psychological brightness and a measurement value of a conventional illuminometer, the first photosensor 24 and the second photosensor are operated by operating the switch 18. The second calculation mode for calculating the illuminance (feeling of brightness) according to the 26 outputs is selected. Note that the illuminance calculated in the second calculation mode differs from the illuminance calculated in the first calculation mode in that the short wavelength component that is the sensitivity region of the S cone contributes to the illuminance value. .

  Similarly to the first calculation mode, light in a wavelength region corresponding to the standard relative luminous sensitivity V (λ) is incident on the first photosensor 24 by the first optical filter 38 out of the light from the light source. The first photosensor 24 generates an electromotive current A1 in accordance with the amount of received light. The electromotive current A1 is converted by the IV converter 28, and further converted to the digital signal D1 by the A-D converter 32. 36. In addition, of the light from the light source, light in a wavelength region corresponding to the sensitivity characteristic SB (λ) of the S cone is incident on the second photosensor 26 by the second optical filter 40. The second photosensor 26 generates an electromotive current A2 in accordance with the amount of received light. The electromotive current is converted by the IV converter 30 and further converted to the digital signal D2 by the AD converter 34. Is input.

In the illuminometer 10 according to the present embodiment, the illuminance (brightness feeling) Leq calculated in the second calculation mode can be expressed by Expression (2).
Brightness Leq = KΣ ^380-780 S (λ) · p (λ) · Vk (λ) · dλ (2)
Here, Vk (λ) = V (λ) + m · SB (λ). The coefficient m is a value that varies depending on the spectral reflection characteristics of the visual target irradiated with light from the light source, and the visibility curve Vk (λ) shown in FIG. 2 is obtained when the visual target is asphalt. . In the present embodiment, when the coefficient m is 1.49, the relationship between the subjective brightness feeling felt by the observer and the measured value of the illuminometer generally corresponds. The coefficient m can be changed by inputting a numerical value from the input unit 16 in accordance with the material or surface state of the visual target that is the measurement target. The coefficient m is a value that determines the ratio at which the output of the second photosensor 26 corresponding to the S cone sensitivity contributes to illuminance (feeling of brightness). For example, according to the study of the present inventor, when the visual object is a gray cotton fabric sample, by inputting 0.63 as the coefficient m from the input unit 16, the subjective brightness feeling and illuminance felt by the observer The relationship with the measured value of the meter generally corresponded.

  Thus, unlike the measurement in the first calculation mode, the brightness in the second calculation mode in consideration of Vk (λ) that is a function of the standard relative luminous sensitivity V (λ) and the S cone sensitivity SB (λ). The measured value of the sensation has a magnitude corresponding to the subjective brightness sensation of the observer, even for an LED light source that contains a large amount of light of the wavelength component that is the sensitivity region of the S cone. Therefore, the illuminance meter according to the present embodiment can calculate the illuminance corresponding to the subjective brightness feeling felt by the observer for various light sources including LED light sources as well as halogen light sources and HID light sources. .

  According to the illuminance meter 10 according to the present embodiment, for example, an LED light source that includes light of a wavelength component that is a sensitivity region of the S cone, the brightness feeling is objectively measured by a method similar to the conventional measurement of illuminance and luminance. Can be measured automatically. Thereby, the discrepancy between the sense of brightness actually felt by the observer and the measured value, which occurs when a specific light source is measured with a conventional measuring apparatus that supports only the standard relative luminous sensitivity, is reduced.

  In addition, the light receiving unit 12 in the illuminometer 10 includes a plurality of photosensors, and can output signals corresponding to the amount of received light. Therefore, an output according to the standard relative luminous sensitivity of the received light amount and an output according to the S cone sensitivity of the received light amount are obtained separately.

  Further, the switch 18 can easily switch between the first calculation mode and the second calculation mode, and a compact illuminance meter having a plurality of functions and good operability can be realized.

[Second Embodiment]
In the first embodiment, an illuminometer including a plurality of physically separated photosensors has been described as an example. The optical measurement apparatus according to the second embodiment realizes the same function as the illuminometer in the first embodiment with a set of spectroscope and CCD. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and overlapping descriptions such as actions and effects are appropriately omitted.

  FIG. 5 is a diagram schematically showing elements of the optical measuring device according to the second embodiment. As shown in FIG. 5, the illuminance meter 110 includes a spectroscope 112, a CCD 114 as a light receiving unit, an IV converter 116, an A / D converter 118, a calculation unit 120, a display unit 14, An input unit 16 and a switch 18 are provided. The spectroscope 112 is a prism or a diffraction grating, for example, and separates incident light by each wavelength. The light split by the spectroscope 112 reaches the light receiving surface of the CCD 114. On the light receiving surface, the region where the dispersed light reaches varies depending on the wavelength. Therefore, the CCD 114 can output a signal corresponding to the amount of light received for each wavelength of the dispersed light. The output signal is input to the arithmetic unit 120 through the IV converter 116 and the AD converter 118. The calculation unit 120 converts the signal output for each wavelength based on the standard specific luminous sensitivity and the S cone sensitivity, or the standard specific visual sensitivity, and calculates illuminance or luminance.

  When the illuminometer 110 according to the present embodiment is used as a normal illuminometer, the switch 18 is operated, and the signal output from the CCD 114 for each wavelength is output to the standard relative luminous sensitivity V (λ) by the arithmetic unit 120. The first calculation mode for converting based on the above and calculating the illuminance is selected. On the other hand, when measuring a light source such as an LED light source that has a discrepancy between psychological brightness and a measurement value of a conventional illuminometer, the switch 18 is operated to output a signal output from the CCD 114 for each wavelength. Then, the calculation unit 120 selects the second calculation mode for calculating the illuminance (feeling of brightness) based on the standard relative luminous sensitivity V (λ) and the S cone sensitivity SB (λ).

  The present invention has been described based on the embodiments and examples. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the above-described embodiment, the illuminometer is described as an example of the optical measuring device, but a luminance meter may be used. In this case, the term “illuminance” can be read as “luminance”. The illuminance is not limited to that measured according to the definition defined in the standard, but refers to a measured value measured by the illuminometer 10. For example, the measurement value measured in the first calculation mode described above can be distinguished from the standard illuminance, and the measurement value measured in the second calculation mode can be distinguished from the brightness illuminance.

  DESCRIPTION OF SYMBOLS 10 Illuminometer, 12 Light-receiving part, 14 Display part, 16 Input part, 18 Switch, 20 Case, 22 Milky white filter, 24 1st photo sensor, 26 2nd photo sensor, 28, 30 I-V converter, 32, 34 AD converter, 36 calculating part, 38 1st optical filter, 40 2nd optical filter.

Claims (6)

When the standard relative luminous sensitivity is V (λ) and the S cone sensitivity is SB (λ), the illuminance or luminance of incident light based on a function of V (λ) + m · SB (λ) (m is a positive coefficient) Optical measurement device that calculates A light receiving unit that outputs a signal corresponding to the amount of light received;
Sensitivity characteristics for each wavelength at the light receiving part are V (λ) + m × SB (λ) (m is a positive coefficient) where V (λ) is the standard relative luminous sensitivity and SB (λ) is the S cone sensitivity. A sensitivity correction unit that selectively transmits incident light to the light receiving unit so that a sensitivity curve according to the function of
An arithmetic unit that calculates illuminance or luminance according to the output of the light receiving unit;
An optical measuring device comprising: The light receiving unit includes a first photoelectric conversion element and a second photoelectric conversion element,
The sensitivity correction unit
A first optical filter that selectively transmits incident light to the first photoelectric conversion element so that a sensitivity characteristic for each wavelength in the first photoelectric conversion element is a sensitivity characteristic corresponding to a standard relative luminous sensitivity;
A second optical filter that selectively transmits incident light to the second photoelectric conversion element so that a sensitivity characteristic for each wavelength in the second photoelectric conversion element is a sensitivity characteristic corresponding to S cone sensitivity; Have
The optical measurement apparatus according to claim 2, wherein the first photoelectric conversion element and the second photoelectric conversion element each output a signal corresponding to an amount of received light.   A first calculation mode for calculating illuminance or luminance in accordance with the output of the first photoelectric conversion element in the arithmetic unit, and illuminance in accordance with the outputs of the first photoelectric conversion element and the second photoelectric conversion element in the arithmetic unit. The optical measurement apparatus according to claim 3, further comprising a switching unit that switches between a second calculation mode for calculating luminance. A spectroscopic unit that outputs a signal corresponding to the amount of received light corresponding to each wavelength;
A calculation unit which calculates a illuminance or a luminance according to a sensitivity curve corresponding to the standard specific visual sensitivity and the S cone sensitivity from the signal;
The optical measuring device according to claim 1, comprising:   5. The optical measurement apparatus according to claim 4, further comprising an input unit that inputs a coefficient that determines a rate at which an output of the second photoelectric conversion element contributes to illuminance or luminance in the second calculation mode.

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