Photometry device and photometry method

Abstract

The invention provides a photometry device and a photometry method, which can realize the enlargement of the dynamic range by inserting and pulling out a light attenuation part in the optical path of the measured light, and can inhibit the increase of the measurement error. A photometric device is provided with: a branching optical system for branching light to be measured from an object to be measured into a plurality of light beams; the color measurement optical system includes a wavelength selection filter on which the light to be measured branched by the branching optical system is incident, and a light receiving sensor that receives the light to be measured that has passed through the wavelength selection filter, the color measurement optical system being further provided with a light attenuation member that can be inserted into and removed from the optical path of the light to be measured. The light attenuation member is disposed in front of the branching optical system.

Description

Technical Field

[0001] The present invention relates to a photometric device and a photometric method capable of measuring the brightness, chromaticity, etc. of light emitted from a measurement object such as a display of a smartphone or a liquid crystal monitor. Background Art

[0002] As a photometric device as described above, there is known a Fig.24 As shown, a photometric device 100 includes a branching optical system 120 that branches a light 201 to be measured from a measurement object 200 into a plurality of light beams (eg, Patent Document 1).

[0003] The photometric device 100 includes an objective optical system 110 composed of a convex lens, etc., a branching optical system 120, and colorimetric optical systems 130 to 150. In the branching optical system 120, as an example, an optical fiber bundle is used. The optical fiber bundle is formed by bundling a plurality of bare optical fibers with small diameters, and randomly branching them into a plurality of fibers (for example, three corresponding to the three stimulus values ​​of the color function X, Y, and Z specified by CIE (International Commission on Illumination)) on the output end (exit) side and bundling each plurality of fibers. In addition, a diffuser is sometimes used as the branching optical system 120.

[0004] As the colorimetric optical systems 130 to 150 , for example, combinations of wavelength selection filters and light receiving sensors are used in a number equal to the number of branches of the branching optical system 120 .

[0005] After the light received by each light receiving sensor is converted into an electrical signal, the corresponding electrical processing unit 161a to 161c performs I / V conversion, amplification and other processing, and then inputs it as light receiving data to the control unit 162. The control unit 162 performs calculations based on the input light receiving data to calculate the measurement value.

[0006] However, in recent years, displays with a large luminance dynamic range have been used in smartphones and the like. Therefore, photometric devices are required to have the ability to measure from dark luminance to bright luminance when performing gamma inspection and adjustment.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 5454675 Summary of the invention

[0010] Technical problem to be solved by the invention

[0011] In order to expand the dynamic range of the photometric device 100, it is necessary to control the amount of received light according to the constraints of the photoelectric conversion capability of the light receiving sensor (saturation of the light receiving sensor) and the design conditions of the electrical processing units 161a to 161c. Therefore, it is considered to insert or remove a light attenuating component according to the brightness of the object 200 in the optical path of the light 201 to be measured that is emitted from the object 200 and enters the light receiving sensor.

[0012] However, the research conducted by the inventors has revealed that, depending on the insertion and removal position of the light attenuation component in the optical path, multiple reflections are generated between the light attenuation component and other components of the light measuring device 100, such as the wavelength selection filter and light receiving sensor of the colorimetric optical system 130 to 150. As a result, the light receiving spectrum sensitivity of the colorimetric optical system 130 to 150 changes and the measurement error increases.

[0013] The present invention is proposed based on this technical background, and aims to provide a photometric device and a photometric method, which can expand the dynamic range by inserting and removing a light attenuation component in the optical path of the light to be measured, and can suppress the increase of measurement errors.

[0014] Technical solutions for solving technical problems

[0015] The above purpose is achieved through the following technical solutions.

[0016] (1) A light measuring device comprising:

[0017] a branching optical system that branches the light to be measured from the object to be measured into a plurality of light;

[0018] A colorimetric optical system comprising a wavelength selective filter and a light receiving sensor, wherein the wavelength selective filter is incident with the light to be measured branched by the branching optical system, and the light receiving sensor receives the light to be measured that has passed through the wavelength selective filter, characterized in that:

[0019] It also includes a light attenuation component that can be inserted and removed from the optical path of the light to be measured,

[0020] The light attenuating member is arranged in front of the branching optical system.

[0021] (2) The photometric device according to item 1 above,

[0022] The light attenuation component is inserted and removed according to the brightness of the object to be measured.

[0023] (3) The photometric device according to item 1 or 2 above,

[0024] The light attenuating component is composed of a thin film filter.

[0025] (4) The photometric device according to item 1 or 2 above,

[0026] The light receiving sensor is a silicon sensor.

[0027] (5) The photometric device according to item 1 or 2 above,

[0028] The wavelength selection filter is a thin film filter.

[0029] (6) The photometric device according to item 1 or 2 above,

[0030] The branching optical system is a diffusion plate.

[0031] (7) The photometric device according to item 1 or 2 above,

[0032] The branching optical system is an optical fiber bundle.

[0033] (8) The photometric device according to item 7 above,

[0034] The length of the optical fiber bundle is more than 50 times the core diameter of the bare wire.

[0035] (9) The photometric device according to item 1 or 2 above,

[0036] A reflecting mirror is provided in front of the branching optical system for guiding the measured light to the observation optical system.

[0037] The light attenuation component is arranged between the reflecting mirror and the branching optical system.

[0038] (10) The photometric device according to item 1 or 2 above,

[0039] The wavelength selection filter is a color-selective filter.

[0040] (11) The photometric device according to item 1 or 2 above,

[0041] The wavelength selection filter is a spectral filter, and the light receiving sensor is a line sensor.

[0042] (12) A light measuring method, characterized in that a light measuring device comprises:

[0043] a branching optical system that branches the light to be measured from the object to be measured into a plurality of light;

[0044] The colorimetric optical system comprises a wavelength selective filter for incident light to be measured branched by the branching optical system and a light receiving sensor for receiving light to be measured transmitted through the wavelength selective filter.

[0045] At a position of the photometric device that is forward of the branch optical system,

[0046] A light attenuating component is inserted and removed in the optical path of the light to be measured.

[0047] Effects of the Invention

[0048] According to the photometric device and the photometric method of the present invention, the light attenuation component is arranged in front of the branching optical system and is inserted and removed in the optical path of the light to be measured. When the light attenuation component is inserted in the optical path, the light to be measured that passes through the light attenuation component and is branched by the branching optical system is transmitted through the wavelength selection filter and received by the light receiving sensor, and a part of the light to be measured is reflected by the surface of the wavelength selection filter and the light receiving sensor.

[0049] The measured light reflected by the colorimetric optical system passes through the branch optical system and returns to the light attenuation component, but diffuses and exits from the branch optical system due to passing through the branch optical system. As a result, the intensity of the light that goes straight to the light attenuation component decreases. Although the straight light is reflected by the light attenuation component and passes through the branch optical system again to reach the colorimetric optical system, the intensity of the reflected light also decreases. The reflected light that returns to the colorimetric optical system is received by the light receiving sensor, but a part of it is reflected again by the colorimetric optical system and returns to the light attenuation component. The above steps are repeated, and multiple reflections occur between the light attenuation component and the colorimetric optical system. However, each time the reflected light returns to the branch optical system, it is scattered. As a result, the influence of the total reflected light received by the light receiving sensor is particularly small.

[0050] That is, by inserting and removing the light attenuation component in the optical path of the measured light ahead of the branching optical system, the influence of multiple reflections generated between the light attenuation component and the colorimetric optical system can be reduced, thereby suppressing changes in the spectral sensitivity of the received light and suppressing increases in measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a block diagram showing the internal structure of the photometric device in Embodiment 1 of the present invention.

[0052] Figure 2 This is an explanatory diagram of a light attenuation component using a thin film filter.

[0053] Figure 3 This is a graph showing an example of actual transmittance per wavelength of a glass absorption filter and a thin film filter both of which have a transmittance of T ≈ 5%.

[0054] Figure 4 This is a graph comparing the transmittance for each wavelength and the color-matching function Y when a glass absorption filter and a thin film filter are respectively combined with a Y filter as a wavelength selection filter.

[0055] Figure 5 This is a graph showing an example of the reflection characteristics of a silicon sensor used as a light receiving sensor.

[0056] Figure 6 (A) is a schematic diagram for explaining the reflection of incident light by an interference film filter used as a wavelength selective filter. Figure 6 (B) is a graph of the transmittance and reflectance of the interference film filter.

[0057] Figure 7 (A) Figure 7 (B) is a graph showing an example of the transmittance and reflectance in the visible light region (wavelength 380 to 780 nm) of a light attenuating member composed of a thin film filter whose thin film is a metal oxide film of niobium oxide.

[0058] Figure 8 This is a structural diagram of a photometric device in which the insertion and removal position of the light attenuation component is between the wavelength selection filter and the light receiving sensor.

[0059] Fig. 9 is Figure 8 Schematic diagram illustrating multiple reflections occurring between the light attenuation component, the wavelength selection filter, and the light receiving sensor in the structure.

[0060] Fig.10 (A) is a diagram showing the transmission and reflection of the measured light with a wavelength of about 500 nm when a Y filter is used as an example. Fig.10 (B) is a diagram showing the state of transmission and reflection of the light to be measured in a state where a light attenuation member is inserted behind the Y filter.

[0061] Fig.11 This is a graph that examines the influence of multiple reflections between the light attenuation member and the wavelength selection filter in a state where the light attenuation member is inserted behind the wavelength selection filter.

[0062] Fig.12 The diagram shows the state of transmission, reflection, and reception of the light to be measured in a state where a light attenuating member is inserted in front of the light receiving sensor.

[0063] Fig.13 This is a graph that examines the influence of multiple reflections between the light attenuation member, the wavelength selection filter, and the light receiving sensor in a state where the light attenuation member is inserted behind the wavelength selection filter.

[0064] Fig.14 This is a structural diagram of the photometric device when the insertion and removal position of the light attenuation component is in front of the wavelength selection filter.

[0065] Fig.15 is Fig.14 Schematic diagram illustrating multiple reflections occurring between the light attenuation component, the wavelength selection filter, and the light receiving sensor in the structure.

[0066] Fig.16 This is a schematic diagram for explaining why the influence of multiple reflection is reduced in the structure of the first embodiment.

[0067] Fig.17 This is a block diagram showing the internal structure of a photometric device in Embodiment 2 of the present invention.

[0068] Fig.18 (A) Fig.18 (B) is a diagram for explaining the light mixing effect of the optical fiber.

[0069] Fig.19 (A) Fig.19 (B) is a diagram for explaining the light mixing effect of the optical fiber.

[0070] Fig. 20 This is a block diagram showing the internal structure of a photometric device in Embodiment 3 of the present invention.

[0071] Fig.21 This is a block diagram showing the internal structure of a photometric device in Embodiment 4 of the present invention.

[0072] Fig. 22 This is a block diagram showing the internal structure of a photometric device in Embodiment 5 of the present invention.

[0073] Fig.23 This is a flowchart for explaining the method of controlling the insertion and removal of the light attenuating member implemented by each photometric device according to the present embodiment.

[0074] Fig.24 This is a block diagram showing a general structure of a light measuring device. DETAILED DESCRIPTION

[0075] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0076] [Implementation Method 1]

[0077] <Overall structure>

[0078] Figure 1 This is a block diagram showing the structure of a tristimulus value type photometric device according to one embodiment of the present invention.

[0079] exist Figure 1 In the embodiment, the photometric device 10 is used, for example, in an inspection process of a production line for smartphone displays, and measures the brightness, chromaticity, etc. of a display surface of a display as a measurement target 1 .

[0080] The photometric device 10 includes an objective optical system 11, a branching optical system 12, colorimetric optical systems 13 to 15, and a light attenuating member 40. A convex lens 11a having positive refractive power is used in the objective optical system 11. A diffuser plate 20 having branching and diffusing functions is used in the branching optical system 12.

[0081] An aperture stop 11b is disposed at the rear focal position of the convex lens 11a, and is a front telecentric optical arrangement in order to take in a component within a predetermined angle (e.g., ±2.5 degrees) relative to the normal line of the display surface, i.e., the measured surface, of the measured object 1. The diffuser 20 is disposed at the rear of the aperture stop 11b surface.

[0082] A light attenuation component 40 is disposed between the convex lens 11a and the diffuser 20 and in front of the aperture stop 11b surface. The light attenuation component 40 is driven by an insertion and extraction device 50 as a driving device to be inserted into or withdrawn from the optical path of the measured light 2. The insertion and extraction device 50 is composed of, for example, a linear actuator. When the light attenuation component 40 is inserted into the optical path of the measured light 2, the light amount of the measured light 2 incident on the diffuser 20 is reduced by the light attenuation component 40. When the light attenuation component 40 is withdrawn from the optical path of the measured light 2, the light amount of the measured light 2 is not reduced and is incident on the diffuser 20.

[0083] The light attenuation member 40 is inserted and removed according to the brightness of the object 1 to be measured. Specifically, it is in a retracted state when the object 1 to be measured is dark, and is inserted into the optical path when the object 1 to be measured is bright, and the saturation of the light receiving sensors 13b, 14b, and 15b is prevented by reducing the amount of light. As a result, the intensity of the light 2 to be measured can be set within the dynamic range of the light receiving sensors 13b, 14b, and 15b, resulting in an expansion of the dynamic range of the light measuring device 10. In the following description, the light attenuation member is also referred to as an ND filter.

[0084] The light attenuation component 40 is preferably arranged near the focusing position (the position of the aperture stop 11b) of the objective optical system 11. In the light receiving optical path of the measured light 2, the effective optical path at the aperture stop position is small. The smaller the effective optical path, the smaller the size of the light attenuation component 40 can be, the smaller the plug-in device 50 can be, and the driving torque can be low torque. Therefore, the product size becomes compact, lightweight, and the cost becomes low. It should be noted that the aperture stop 11b may not be provided.

[0085] There is no limitation on the type of the light attenuation component 40, and various components such as thin film filters, glass absorption filters, and porous plates can be used. However, it is very important that the light attenuation component 40 has spectral flatness (uniformity). This is because flatness affects the spectral responsivity in the plug-in and unplugged state of the light attenuation component 40 (with or without the light attenuation component 40). In the case of unevenness, the light receiving spectrum sensitivity when there is no light attenuation component 40 (withdrawn from the optical path) and the light receiving spectrum sensitivity when there is the light attenuation component 40 (inserted into the optical path) change. If the light receiving spectrum sensitivity deviates from the isochromatic function, it becomes an error in luminance chromaticity. In addition, it is also very important that there are no changes caused by ambient temperature, etc.

[0086] The spectral flatness of the glass absorption filter is poor, and the transmittance change caused by the ambient temperature is also large. Although the porous plate has spectral flatness, it produces measurement unevenness in the light receiving angle. In addition, strict position reproducibility is required. The spectral flatness of the thin film filter is good, and the reliability based on the ambient temperature is also high. Therefore, the thin film filter can be used as the light attenuation component 40.

[0087] Figure 2 An example of the light attenuation member 40 using a thin film filter is shown.

[0088] Reference Figure 2 The light attenuation component 40 includes films 42, 43 and a transparent substrate 41 supporting the films 42, 43. The transparent substrate 41 is formed of an optical material such as glass, plastic, crystal or sapphire that is transparent to the measured light 2. The transparent optical material forming the transparent substrate 41 can be appropriately selected according to the wavelength range of the measured light 2.

[0089] The thin films 42 and 43 are respectively formed on at least one of the incident surface 41a and the exit surface 41b of the corresponding transparent substrate 41. Specifically, the light attenuating member 40 includes at least one of the thin films 42 and 43. The thin film 42 is formed on the incident surface 41a of the transparent substrate 41. The thin film 43 is formed on the exit surface 41b of the transparent substrate 41. Specifically, the thin films 42 and 43 are formed on both the 41a and the exit surface 41b of the corresponding transparent substrate 41.

[0090] Specifically, the light attenuation component 40 includes a thin film 42 formed on the incident surface 41a of the transparent substrate 41 and a thin film 43 formed on the emission surface 41b of the transparent substrate 41. The thin films 42 and 43 may have the same film structure as each other, or may have different film structures from each other. The thin films 42 and 43 may be formed of the same material as each other, or may be formed of the same material as each other. The thin films 42 and 43 may be, for example, interference films using a dielectric material such as SiO2 or MgF2 as its material, or may be metal oxide films using a metal oxide material such as Al2O3, TiO2, Nb2O5 or NbO as its material. Alternatively, a metal material such as Cr or Nb may be used.

[0091] As the light attenuation component 40, an absorption-type light attenuation component that absorbs light inside a substrate (e.g., a glass substrate) is known. The degree of freedom in designing the transmission spectrum of the absorption-type light attenuation component is relatively low. In addition, the stability of the absorption-type light attenuation component with respect to the ambient temperature and the ambient humidity is relatively low. In contrast, the degree of freedom in designing the transmission spectrum of the interference-type light attenuation component (e.g., the light attenuation component 40 including the thin films 42 and 43 formed of interference films) is relatively high. In addition, the stability of the interference-type light attenuation component with respect to the ambient temperature and the ambient humidity is relatively high.

[0092] Figure 3 The actual transmittance of each wavelength in the visible light region (wavelength 380-780nm) of the glass absorption filter and the thin film filter is for reference only. The average transmittance is T≒5%. Figure 4 In FIG. 1 , the transmittance of each wavelength when the glass absorption filter and the thin film filter are respectively combined with the Y filter 14a among the color filters 13a, 14a, and 15a is compared with the color function Y. Figure 3 and Figure 4 The thin film filter shown uses a niobium oxide film and a chromium oxide film as thin films.

[0093] like Figure 3 As shown in the figure, the spectral flatness of the thin film filter is better than that of the glass absorption filter. Figure 4 As shown, although a deviation from the isochromatic function occurs in the case of a glass absorption filter, there is almost no deviation in the case of a thin film filter.

[0094] The colorimetric optical systems 13, 14, 15 include isochromatic function filters corresponding to the three stimulus values ​​X, Y, Z, i.e., wavelength selection filters (also referred to as color filters in the following description) 13a, 14a, 15a, and light receiving sensors 13b, 14b, 15b used in combination with them.

[0095] The color filters 13a, 14a, and 15a may also be formed by stacking a plurality of light absorption filters so that the incident light has a transmittance corresponding to the desired spectral characteristics of the three stimulus values ​​X, Y, and Z. However, in such a structure, there is a problem that it is impossible to design a filter with transmittance peaks in two wavelength regions, that is, the degree of freedom in filter design is small. In addition, light absorption filters also have the problem of low transmittance and large light loss. Moreover, especially in film-shaped color filters, there is also a problem of drastic changes over the years (poor stability) with respect to heat, light (ultraviolet rays), humidity, etc.

[0096] Therefore, it is preferable to use interference filters (hereinafter referred to as interference film filters) instead of light absorption filters for the color filters 13a, 14a, and 15a. The interference film filter is a filter formed by laminating dozens of layers of dielectrics or oxides on a glass substrate by vacuum evaporation or sputtering, and is a wavelength-selective filter that transmits or reflects light by interference.

[0097] Therefore, compared with the above-mentioned light absorption type filter, the interference film filter can easily obtain the desired transmittance (that is, it is easy to design and has a high degree of freedom in design), and can also produce a filter with two peaks (mountains) like the isochromatic function X. In addition, since the transmittance of the interference film filter is high, for example, the peak transmittance is less than 50% in the absorption type, while it is close to 100% in the interference type. In addition, the interference film filter has the advantage of excellent reliability (little change in transmittance over time due to temperature, humidity, and exposure).

[0098] In this embodiment, silicon sensors are used as the light receiving sensors 13b, 14b, and 15b.

[0099] After the light received by each light receiving sensor 13b, 14b, 15b is converted into an electric signal, the corresponding electric processing unit 16a, 16b, 16c performs I / V conversion, amplification and other processing, and then inputs it as light receiving data to the control unit 17. The control unit 17 performs calculations based on the input light receiving data to calculate the measurement value.

[0100] However, when the light 2 to be measured reaches the color filters 13a, 14a, and 15a of the color measurement optical system 13, the light 2 to be measured passes through the color filters 13a, 14a, and 15a, but a part of the light 2 to be measured is reflected by the surface of the color filters 13a, 14a, and 15a. A part of the reflected light returns to the light attenuation member 40 and is reflected again by the surface of the light attenuation member 40, and the reflected light is repeatedly passed through and reflected by the color filters 13a, 14a, and 15a. In this way, multiple reflections are repeatedly performed between the color filters 13a, 14a, and 15a and the light attenuation member 40.

[0101] On the other hand, the light to be measured 2 that passes through the color filters 13a, 14a, 15a and reaches the light receiving sensors 13b, 14b, 15b is received by the light receiving sensors 13b, 14b, 15b, but part of the light to be measured 2 is reflected by the surface of the light receiving sensors 13b, 14b, 15b. Part of the reflected light passes through the color filters 13a, 14a, 15a and returns to the light attenuation member 40, and is reflected again by the surface of the light attenuation member 40, and the reception and reflection of the reflected light that is reflected again are repeated in the light receiving sensors 13b, 14b, 15b. In this way, multiple reflections are repeated between the light receiving sensors 13b, 14b, 15b and the light attenuation member 40.

[0102] The inventors have discovered that by making the behavior of multiple reflections occurring between the light attenuation component 40 and the color filters 13a, 14a, 15a, and the light receiving sensors 13b, 14b, 15b greatly different depending on the position of the light attenuation component 40 when it is plugged in or out, and by plugging and unplugging the light attenuation component in front of the branch optical system 12, the influence of multiple reflections on the measured values ​​can be reduced.

[0103] Figure 5 An example of the reflection characteristics of the silicon sensors used as the light receiving sensors 13b, 14b, and 15b is shown.

[0104] Generally, the silicon sensor converts about 1 / 3 of the input light energy into electricity and sends it to the electrical processing units 16a, 16b, 16c and the control unit 17. About 1 / 3 is converted into heat and released into the atmosphere. About 1 / 3 is reflected. Figure 5 As shown, the reflectivity of the silicon sensor also depends on the wavelength range of the light to be measured, but is 30 to 40%.

[0105] The interference film filters used as the color filters 13a, 14a, and 15a have almost no absorption by the film material (dielectric). Figure 6 As shown in (A), light rays other than the transmitted light rays among the incident light rays (light rays to be measured) are reflected by each layer and become reflected light rays.

[0106] Figure 6 (B) is a graph showing the transmittance and reflectance of an interference film filter as an X-ray filter. In this graph, the black portion inside the characteristic curve of transmittance versus wavelength corresponds to transmitted light, and the white portion outside corresponds to reflected light, and transmittance + reflectance ≒ 100%.

[0107] Figure 7 (A) and Figure 7(B) shows an example of the transmittance and reflectance in the visible light region (wavelength 380 to 780 nm) of a light attenuation component (denoted as ND filter in the figure) composed of a thin film filter whose thin film is a metal oxide film of niobium oxide. The average transmittance is ≒5%, and the average reflectance is ≒10%.

[0108] Next, regarding the reason why the influence of multiple reflections on the measured value can be reduced by inserting and removing the light attenuating member 40 in front of the branching optical system 12, the case where the light attenuating member 40 is inserted and removed between the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b (refer to Figure 8 ), and between the color filters 13a, 14a, 15a and the diffuser 20 (refer to Fig.14 ) are compared and explained.

[0109] <When the insertion and removal position of the light attenuating member 40 is between the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b>

[0110] In this case, if Fig. 9 As schematically shown in FIG. 1 , multiple reflections occur between the light attenuation component 40 and the color filters 13a, 14a, and 15a. In addition, multiple reflections also occur between the light attenuation component 40 and the light receiving sensors 13b, 14b, and 15b. Fig. 9 In FIG. 1 , the color filter 14a and the light receiving sensor 14b are representatively shown, but the same is true for the other color filters 13a and 15a and the light receiving sensors 13b and 15b.

[0111] (1) Multiple reflections between the light attenuating member 40 and the color filters 13a, 14a, and 15a

[0112] Fig.10 (A) shows the transmission and reflection of the measured light 2 with a wavelength of about 500 nm, taking the color filter 14a as an example, which is a Y filter. The transmittance T and reflectance R of the Y filter 14a are set to T ≒ 30% and R ≒ 70%, respectively. When the intensity of the incident light is set to 1, the intensity of the transmitted light is 0.30, and the intensity of the reflected light is 0.70.

[0113] Next, consider Fig.10 (B) The light attenuating member 40 is inserted behind the Y filter 14a. The transmittance T and reflectance R of the light attenuating member 40 are set to T=5% and R=10%, respectively.

[0114] The intensity of the transmitted light having an intensity of 0.3 that has passed through the Y filter 14a becomes 0.015 (=0.30×0.05) when it passes through the light attenuating member 40. On the other hand, the intensity of the reflected light reflected by the light attenuating member 40 becomes 0.03 (=0.30×0.1).

[0115] The reflected light with an intensity of 0.03 reflected by the light attenuating member 40 returns to the Y filter 14 a , but is reflected again by the Y filter 14 a as reflected light with an intensity of 0.021 (=0.03×0.7) and enters the light attenuating member 40 .

[0116] The reflected light with an intensity of 0.021 passes through the light attenuating member 40. The intensity of the transmitted light is 0.00105 (=0.021×0.05). It should be noted that a part of the reflected light with an intensity of 0.021 is reflected by the light attenuating member 40, but the subsequent multiple reflections are negligible.

[0117] Due to the behavior of the light to be measured 2 described above, the total intensity of the light to be measured 2 transmitted through the light attenuating member 40 is 0.01605 (=0.015+0.00105).

[0118] Next, the same calculations were performed for the wavelength range of 380 to 780 nm for each of the X filter 13a, the Y filter 14a, and the Z filter 15a, in the state where the light attenuation member 40 was inserted and in the state where the light attenuation member 40 was retracted. The results are shown in FIG. Fig.11 (A1)~(A3).

[0119] The curve of "without ND" is the received light intensity in the state where the light attenuation member 40 is retracted, and is the intensity of light when the measured light 2 of intensity 1 is input to each color filter 13a to 15a and passes through the color filters 13a to 15a. The curve of "with ND" is the received light intensity in the state where the light attenuation member 40 is inserted, and is the intensity of light when the measured light 2 of intensity 1 is input to each color filter 13a to 15a and passes through the light attenuation member 40 (including light that is re-transmitted due to reflection).

[0120] Fig.11 (B1) to (B3) are to make the evaluation criteria the same. Fig.11 The characteristics of (A1) to (A3) are graphs normalized by area. In any graph, there is a slight difference in the received light intensity between "with ND" and "without ND" depending on the presence or absence of the light attenuating member 40.

[0121] In order to make clear the difference in received light intensity due to the presence or absence of the light attenuation member 40, Fig.11In (B1) to (B3), the dotted lines represent the results of calculating the received light intensity of "with ND" / the received light intensity of "without ND". The vertical axis of the dotted line is shown on the right. When there is no difference, the vertical axis is "1", and the larger the value, the larger the difference.

[0122] (2) Multiple reflections between the light attenuating member 40 and the light receiving sensors 13b, 14b, and 15b

[0123] Fig.12 The light attenuation member 40 and the light receiving sensors 13b, 14b, 15b show the transmission, reflection, and reception of the light 2 to be measured. The transmittance T and reflectance R of the light attenuation member 40 are set to T=5% and R=10%, respectively, and the photoelectric conversion rate and reflectance R of the light receiving sensors (silicon sensors) 13b, 14b, 15b are set to photoelectric conversion rate ≒30% and R≒30%, respectively.

[0124] When the intensity of incident light is set to 1, the intensity of transmitted light passing through the light attenuating member 40 is 0.05, and the intensity of reflected light is 0.10.

[0125] The transmitted light with an intensity of 0.05 that has passed through the light attenuating member 40 reaches each light receiving sensor 13b, 14b, 15b, is received by each light receiving sensor 13b, 14b, 15b, and undergoes photoelectric conversion. The intensity of the photoelectrically converted light is 0.015 (= 0.05 × 0.3). A portion of the light that has reached the light receiving sensors 13b, 14b, 15b is reflected by the light receiving sensors 13b, 14b, 15b. The intensity of the reflected light is 0.015 (= 0.05 × 0.3).

[0126] The reflected light with an intensity of 0.015 reflected by the light receiving sensors 13b, 14b, and 15b returns to the light attenuation member 40, but part of it is reflected again by the light attenuation member 40 and enters the light receiving sensors 13b, 14b, and 15b, and part of it is transmitted through the light attenuation member 40 and returns to the direction of the branching optical system 12. The intensity of the light reflected again and entering the light receiving sensors 13b, 14b, and 15b is 0.0015 (= 0.015 × 0.1), and the intensity of the light transmitted through the light attenuation member 40 and returned to the direction of the branching optical system 12 is 0.00075 (= 0.015 × 0.05).

[0127] A portion of the reflected light with an intensity of 0.0015 that enters the light receiving sensors 13b, 14b, and 15b again is received by the light receiving sensors 13b, 14b, and 15b and photoelectrically converted. The intensity of the photoelectrically converted light is 0.00045 (=0.0015×0.3). It should be noted that a portion of the reflected light with an intensity of 0.0015 is reflected by the light receiving sensors 13b, 14b, and 15b, but the subsequent multiple reflections are ignored.

[0128] According to the behavior of the light to be measured described above, the total intensity of the light to be measured photoelectrically converted by the light receiving sensors 13b, 14b, and 15b is 0.01545 (=0.015+0.00045).

[0129] (3) Influence of multiple reflections occurring between the light attenuating member 40, the color filters 13a, 14a, 15a, and the light receiving sensors 13b, 14b, 15b

[0130] Next, regarding the wavelength region of 380 to 780 nm for each of the X filter 13a, the Y filter 14a, and the Z filter 15a, the total intensity of the photoelectrically converted light when the measured light 2 of intensity 1 is incident on each color filter 13a, 14a, and 15a and is photoelectrically converted by each light receiving sensor 13b, 14b, and 15b in the state where the light attenuation component 40 is inserted and the state where the light attenuation component 40 is retracted is calculated. Fig.13 These results are shown in (A1) to (A3).

[0131] The curve of "without ND" is the intensity of the photoelectrically converted light (received light intensity) in the state where the light attenuation member 40 is retracted, and is the intensity of the light to be measured 2 of intensity 1 input to each color filter 13a, 14a, 15a, and transmitted through the color filter and received by the light receiving sensors 13b, 14b, 15b and photoelectrically converted. The curve of "with ND" is the received light intensity in the state where the light attenuation member 40 is inserted, and is the intensity of the light to be measured 2 of intensity 1 input to each color filter 13a, 14a, 15a, and transmitted through the light attenuation member 40 and received by each light receiving sensor 13b, 14b, 15b and photoelectrically converted (including light received again due to reflection).

[0132] Fig.13 (B1) to (B3) are to make the evaluation criteria the same. Fig.13 The characteristics of (A1) to (A3) are graphs normalized by area. In any graph, there is a slight difference in the intensity of received light depending on the presence or absence of the light attenuating member 40.

[0133] In order to make clear the difference in received light intensity due to the presence or absence of the light attenuation member 40, Fig.13 In (B1) to (B3), the dotted lines indicate the results of calculating the light intensity of "with ND" / the light intensity of "without ND". The vertical axis of the dotted line is shown on the right. When there is no difference, the vertical axis is "1", and a larger value indicates a larger difference.

[0134] Such a difference in received light intensity is considered to be due to the influence of multiple reflections between the color filters 13a, 14a, and 15a, the light attenuating member 40, and the light receiving sensors 13b, 14b, and 15b.

[0135] Specifically, when there is no light attenuation member 40, in the case where the design of the light attenuation member 40 (for example, the transmittance of the objective optical system 11, etc., the transmittance of the color filters 13a, 14a, 15a, the sensitivity of the light receiving sensors 13b, 14b, 15b, etc.) is set to be consistent with the isochromatic function, the light receiving spectrum sensitivity changes due to multiple reflections between the color filters 13a, 14a, 15a, the light attenuation member 40, and the light receiving sensors 13b, 14b, 15b generated when the light attenuation member 40 is inserted. That is, since the light receiving spectrum sensitivity deviates from the isochromatic function, it is considered that the measurement error of the luminance and chromaticity increases.

[0136] <When the insertion and removal position of the light attenuating member 40 is between the color filters 13 a , 14 a , 15 a and the diffusion plate 20 >

[0137] for Fig.14 In this case, as shown in Fig.15 As schematically shown, multiple reflections occur between the light attenuating member 40 and the light receiving sensors 13b, 14b, 15b, and between the light attenuating member 40 and the color filters 13a, 14a, 15a. Therefore, as described in the above-mentioned "When the insertion and removal position of the light attenuating member 40 is between the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b", the light receiving intensity of the light receiving sensors 13b, 14b, 15b differs depending on the presence or absence of the light attenuating member 40, and it is estimated that this affects the increase of the measurement error.

[0138] <When the insertion and removal position of the light attenuation member 40 is in front of the branching optical system 12>

[0139] Then, if Figure 1 The reason why the measurement error is suppressed when the insertion and removal position of the light attenuating member 40 is in front of the diffuser plate 20 as the branching optical system 12 as in the first embodiment shown will be described.

[0140] In this case, when the light attenuating member 40 is inserted, reflected light from the color filters 13 a , 14 a , and 15 a and reflected light from the light receiving sensors 13 b , 14 b , and 15 b also returns to the diffuser 20 and returns to the light attenuating member 40 through the diffuser 20 .

[0141] However, if Fig.16As shown in the schematic diagram, the light returning to the diffuser plate 20 is diffused and transmitted (angle expansion) by the diffuser plate 20, so the intensity of the light returning to the light attenuation member 40 in a straight line (angle 0 degree) becomes smaller. Therefore, the intensity of the light reflected again by the light attenuation member 40 and entering the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b again becomes smaller.

[0142] That is, since the influence of multiple reflections on the light receiving intensity of the light receiving sensors 13b, 14b, and 15b is reduced, the ratio of the light receiving spectrum sensitivity deviating from the isochromatic function is reduced, and the measurement error of luminance and chromaticity can be suppressed.

[0143] exist Figure 1 In the photometric device 10 shown, when the brightness of the object 1 to be measured is equal to or less than a predetermined value, the light attenuating member 40 is retracted from the optical path of the light 2 to be measured, and measurement is performed in the absence of the light attenuating member 40 .

[0144] On the other hand, if the brightness of the object to be measured 1 exceeds the predetermined value, the light attenuation member 40 is inserted into the optical path of the light to be measured 2, and the measurement is performed in the state where the light attenuation member 40 exists. The dynamic range of the photometric device 10 is expanded by the presence of the light attenuation member 40. In addition, by inserting the light attenuation member 40 in front of the diffuser 20, the measurement error can be suppressed. As a result, a high-function photometric device 10 capable of performing high-precision measurement with a large dynamic range is obtained.

[0145] [Implementation Method 2]

[0146] like Fig.17 As shown, this embodiment uses an optical fiber bundle 30 to replace the diffuser 20 as the branching optical system 12 in the first embodiment, and the aperture stop 11b is not provided. It should be noted that the aperture stop 11b can also be provided. In addition, condensing lenses 19a, 19b, and 19c are arranged between the output end of the optical fiber bundle 30 and each color filter.

[0147] The light attenuation component 40, the plug-in device 50, the color filters 13a, 14a, 15a, the light receiving sensors 13b, 14b, 15b, the electrical processing units 16a to 16c, the control unit 17 and other components are Figure 1 The same embodiment 1 is the same as that of the embodiment 1, and therefore, the same reference numerals are used and the description thereof is omitted. Fig.17 The electrical processing units 16a, 16b, 16c and the control unit 17 are omitted.

[0148] The optical fiber bundle 30 is formed by bundling a plurality of n (n = hundreds to thousands) bare optical fibers with small diameters (φ = about 0.03 to 0.3 mm) at the inlet side, randomly branching them into a plurality of fibers (in this embodiment, three fibers corresponding to the three stimulus values ​​X, Y, and Z) at the outlet side, and bundling every m fibers. Reference numerals 31, 32, and 33 are branching parts. The shapes of the incident end 30a and the exit ends 31a, 32a, and 33a of each branching part 31, 32, and 33 are arbitrary (circular, rectangular, etc.).

[0149] exist Fig.17 In the photometric device 10, the measured light 2 from the measured object 1 that has passed through the objective optical system 11 passes through the light attenuation component 40 or directly enters the incident end 30a of the optical fiber bundle 30, and then is transmitted within the optical fiber bundle 30 and emitted from the respective exit ends 31a, 32a, and 33a of the three branch parts 31, 32, and 33.

[0150] The emitted light to be measured enters the condensing lenses 19a, 19b, 19c, enters the color filters 13a, 14a, 15a, and further enters the light receiving sensors 13b, 14b, 15b, and is received by the light receiving sensors 13b, 14b, 15b.

[0151] In the second embodiment, in the same manner as in the first embodiment, when the light attenuation component 40 is inserted, a portion of the light to be measured 2 that passes through the optical fiber bundle 30 and enters the color filters 13a, 14a, 15a from the focusing lenses 19a, 19b, 19c and then enters the light receiving sensors 13b, 14b, 15b is reflected by the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b.

[0152] Then, the reflected light returns to the optical fiber bundle 30 , and returns to the light attenuating member 40 through the optical fiber bundle 30 .

[0153] However, if the optical fiber bundle 40 has a length of at least a certain length, the reflection angle is randomized (mixed). Therefore, similarly to the diffuser plate 20, the light emitted from the incident end 30a of the optical fiber bundle 30 to the light attenuation member 40 is diffused, and the intensity of the light returning to the light attenuation member 40 in a straight line (angle 0 degree) becomes smaller. Therefore, the intensity of the light reflected again by the light attenuation member 40 and entering the color filters 13a, 14a, 15a and the light receiving sensors 13b, 14b, 15b again becomes smaller.

[0154] That is, the optical fiber bundle 30 can also obtain the same effect as the diffuser 20, and the influence of multiple reflections on the light intensity of the light receiving sensors 13b, 14b, and 15b becomes smaller. Therefore, the ratio of the light receiving spectrum sensitivity deviating from the isochromatic function becomes smaller, and the measurement error of luminance and chromaticity can be suppressed.

[0155] Here, the mixing effect of the optical fiber bundle 30 will be described.

[0156] Optical fiber uses the difference in refractive index between the core and cladding, ideally, e.g. Fig.18 (A) Fig.18 As shown in (B), the incident light is totally reflected and guided. However, in reality, the emission position and emission angle will randomly change due to the local difference in refractive index (vein) or the local difference in fiber diameter (thickness, thinness), the bending of the reflection surface caused by the bending of the fiber, or the strain of the material (refractive index), etc. The incident light cannot be transmitted in this ideal form, and the emission light is homogenized (the emission position and emission angle are random).

[0157] That is, in the case of an optical fiber of a certain length, the outgoing light is uniformized and emitted at a constant output angle condition regardless of the characteristics of the incident light to the optical fiber (having the same effect as the diffuser 20. A larger amount of light is obtained than the diffuser 20). In the photometric device 10 of the second embodiment, the characteristics of this optical fiber are utilized.

[0158] Fig.19 Indicates the experimental results. Fig.19 (B) is a graph showing the measured data of the optical fiber's output angle. Fig.19 As shown in (A), light (beam of less than ±2 degrees) incident on the optical fiber is measured by a luminance meter (not shown) facing the output end. The optical fiber is bent 90° at one point. In addition, the optical fiber is a plastic optical fiber (NA = 0.5, φ = 1 mm), and its length is changed to 30 mm (×), 50 mm (▲), 100 mm (■), and 300 mm (◆).

[0159] In the case of incident parallel light, according to the Fig.19 (B) When the optical fiber length is 50 mm, the effective aperture angle (width of 5% peak intensity) is about ±35°, and even if it is set to more than 50 mm, the aperture angle is very stable and almost unchanged. On the other hand, when the optical fiber length is 30 mm, the intensity distribution of the emitted light becomes narrower and the degree of mixing (homogenization) is low.

[0160] If a single optical fiber has a length of more than 50 mm, it can be mixed sufficiently evenly. Moreover, the relationship between the incident light, the outgoing light, and the optical fiber length depends on the number of reflections between the core and the cladding when the light is guided in the optical fiber. Therefore, in this experimental data, since the required optical fiber length is 50 mm when φ=1 mm, it is preferred that the optical fiber length is more than 50 times the optical fiber diameter. By using an optical fiber of this length, the output angle is uniformed (so that the output angle has no inherent information), and a stable output angle condition is obtained.

[0161] By making the fiber length of the single-line optical fiber sufficiently long as described above, light with different incident angles is randomly mixed (mixed) while passing through the inside of the optical fiber, and the information of the light must be converted into information that is uniformized by the spread amount specified by the aperture ratio (NA). The above-mentioned sufficient length that can eliminate the information of the incident angle to the optical fiber is 50 times or more of the core diameter as described above.

[0162] For example, when the bare wire diameter of the optical fiber bundle 30 is φ0.03 mm, the length can be set to 1.5 mm or more, and when the bare wire diameter of the optical fiber bundle 30 is φ0.3 mm, the length can be set to 15 mm or more.

[0163] [Implementation method 3]

[0164] The third embodiment includes a finder optical system for a measurer to recognize the periphery of a measurement area.

[0165] That is, Fig. 20 As shown, a reflector M that bends a part of the optical path of the measured light 2 is arranged between the objective optical system 11 and the incident end of the branch optical system 12 (optical fiber bundle 30). In addition, the light beam not reflected by the reflector M is guided to the branch optical system 12, the light receiving sensors 13b, 14b, and 15b, and the brightness and chromaticity are measured. On the other hand, the light beam reflected by the reflector M is guided to the viewfinder optical system 60, and the measuring person can identify the periphery of the measured area. In the figure, reference numerals S1 and S2 are gaps.

[0166] When the light attenuating member 40 is arranged in front of the reflector M, the light attenuating member 40 is inserted and removed due to the brightness of the object 1 and is difficult to be recognized. Therefore, the light attenuating member 40 may be arranged behind the reflector M.

[0167] The structure other than the viewfinder optical system 60, the reflection mirror M, and S1 and S2 is the same as that of the second embodiment, and thus the description thereof is omitted. Fig. 20 In the embodiment of the present invention, the condenser lenses 19a, 19b, and 19c behind the optical fiber bundle 30 are omitted. In addition, the diffuser plate 20 may be used instead of the optical fiber bundle 30.

[0168] [Implementation Method 4]

[0169] In this embodiment 4, if Fig.21 As shown, in Figure 1 In the photometric device 10 of the first embodiment shown, the convex lens 11 a and the aperture stop 11 b as the objective optical system 11 are omitted. Therefore, the measurement light 2 from the measurement object 1 directly enters the light attenuating member 40 .

[0170] The structure other than the objective optical system 11 Figure 1 The photometric device 10 shown is the same, so the description thereof is omitted. It should be noted that an optical fiber bundle 30 may be used instead of the diffuser plate 20 .

[0171] [Implementation method 5]

[0172] In this fifth embodiment, Figure 1 In the photometric device 10 of the first embodiment, the structure of the colorimetric optical system 13 is changed.

[0173] That is, Fig. 22 As shown, a linear gradient filter (LVF) 70 that can continuously change the wavelength as a spectral filter is used instead of the three color filters 13a, 14a, and 15a. In addition, a line sensor 80 is used as a light receiving sensor. However, instead of the line sensor 80, a plurality of light receiving sensors may be used together.

[0174] The structure other than the color measurement optical system 13, 14, 15 Figure 1 The photometric devices 10 shown are the same, and therefore description thereof will be omitted.

[0175] The photometric device 10 of the fifth embodiment also generates multiple reflections between the light attenuation component 40 and the linear gradient filter 70 and the line sensor 80. However, similar to the photometric device 10 of the first embodiment, the diffusion effect of the diffuser 20 on the return light can suppress the influence of the multiple reflections.

[0176] It should be noted that the optical fiber bundle 30 may be used instead of the diffuser plate 20 .

[0177] [Plug-in and pull-out control of optical attenuation components]

[0178] Fig.23 This is a flowchart for explaining a method of controlling the insertion and removal of the light attenuating member 40 implemented by each photometric device 10 of the present embodiment. This control is performed by the control unit 17 .

[0179] After the measurement starts, the light receiving data V is acquired in step S01. X 、V Y 、V Z Next, in step S02, it is determined whether the light attenuating member 40 is inserted into the optical path (on) or retracted from the optical path (off).

[0180] In the case of retreat (off in step S02), in step S03, it is checked whether the light receiving data is less than the threshold value A. If it is smaller (YES in step S03), after referring to the correction coefficient knon in step S04, the stimulus values ​​X, Y, Z, luminance LV, chromaticity x, y are calculated in step S05 and output in step S07.

[0181] If the light receiving data is not less than the threshold value A in step S03 (NO in step S03), the light attenuating component 40 is inserted into the optical path in step S06, and then the process returns to step S01 to obtain the light receiving data again.

[0182] If the light attenuation component 40 is inserted into the optical path in step S02 (on in step S02), then in step S08, it is checked whether the light receiving data is greater than the threshold value B. If it is greater (YES in step S08), after referring to the correction coefficient knd in step S09, the stimulus values ​​X, Y, Z, luminance LV, chromaticity x, y are calculated in step S10 and output in step S07.

[0183] If the light receiving data is not greater than the threshold value B in step S08 (NO in step S08), the light attenuation component 40 is withdrawn from the optical path in step S11, and the process returns to step S01 to obtain the light receiving data again.

[0184] Industrial Applicability

[0185] The present invention can be used as a photometric device capable of measuring the brightness, chromaticity, etc. of light emitted from a measurement object such as a display of a smartphone or a liquid crystal monitor.

[0186] Description of Reference Numerals

[0187] 1: Object to be measured;

[0188] 2: measured light;

[0189] 10: Light measuring device;

[0190] 11: Objective optical system;

[0191] 11a: convex lens;

[0192] 11b: aperture stop;

[0193] 12: Branch optical system;

[0194] 13-15: Color measurement optical system;

[0195] 13a, 14a, 15a: wavelength selective filters;

[0196] 13b, 14b, 15b: light receiving sensors;

[0197] 16, 16a~16c: electrical processing unit;

[0198] 20: diffuser plate;

[0199] 30: optical fiber bundle;

[0200] 30a: incident end;

[0201] 31-33: branch part;

[0202] 31a~33a: emission end;

[0203] 40: light attenuation component;

[0204] 41: Transparent plate;

[0205] 41a: incident surface;

[0206] 41b: exit surface;

[0207] 42, 43: film;

[0208] 50: plug-in device;

[0209] 60: Viewfinder optical system.

Claims

1. A light measuring device comprising: a branching optical system that branches the light to be measured from the object to be measured into a plurality of light; A colorimetric optical system comprising a wavelength selective filter and a light receiving sensor, wherein the wavelength selective filter is incident with the light to be measured branched by the branching optical system, and the light receiving sensor receives the light to be measured that has passed through the wavelength selective filter, characterized in that: It also includes a light attenuation component that can be inserted and removed from the optical path of the light to be measured, The light attenuating member is arranged in front of the branching optical system.

2. The light measuring device according to claim 1, The light attenuation component is inserted and removed according to the brightness of the object to be measured.

3. The light measuring device according to claim 1 or 2, The light attenuating component is composed of a thin film filter.

4. The light measuring device according to claim 1 or 2, The light receiving sensor is a silicon sensor.

5. The light measuring device according to claim 1 or 2, The wavelength selection filter is a thin film filter.

6. The light measuring device according to claim 1 or 2, The branching optical system is a diffusion plate.

7. The light measuring device according to claim 1 or 2, The branching optical system is an optical fiber bundle.

8. The light measuring device according to claim 7, The length of the optical fiber bundle is more than 50 times the core diameter of the bare wire.

9. The light measuring device according to claim 1 or 2, A reflecting mirror is provided in front of the branching optical system for guiding the measured light to the observation optical system. The light attenuation component is arranged between the reflecting mirror and the branching optical system.

10. The light measuring device according to claim 1 or 2, The wavelength selection filter is a color-selective filter.

11. The light measuring device according to claim 1 or 2, The wavelength selection filter is a spectral filter, and the light receiving sensor is a line sensor.

12. A light measurement method, characterized in that: The light measuring device has: a branching optical system that branches the light to be measured from the object to be measured into a plurality of light; The colorimetric optical system comprises a wavelength selective filter for incident light to be measured branched by the branching optical system and a light receiving sensor for receiving light to be measured transmitted through the wavelength selective filter. At a position of the photometric device that is forward of the branch optical system, A light attenuating component is inserted and removed in the optical path of the light to be measured.

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