JP2008292782A - Brightness correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a person to feel almost same brightness of irradiation light regardless of the hue of the irradiation light. <P>SOLUTION: The brightness of the irradiation light is corrected by multiplying a brightness correction coefficient. The brightness correction coefficient is decreased according as the chromaticity of the irradiation light on the CIE1931 chromaticity coordinates is away from the coordinate position of a white color w as a reference. The brightness correction coefficient is 0.90 to 1.00 when the color of the irradiation light is light yellow ty; the coefficient is 0.69 to 0.85 when the color is pink tr; the coefficient is from 0.66 to 0.80 when the color is yellow y; the coefficient is 0.61 to 0.75 when the color is yellow green yg; the coefficient is 0.58 to 0.70 when the color is light green tg; the coefficient is 0.54 to 0.66 when the color is blue green bg; the coefficient is 0.53 to 0.65 when the color is light blue tb; the coefficient is 0.45 to 0.55 when the color is green g; the coefficient is from 0.37 to 0.45 when the color is mandarin m; the coefficient is 0.26 to 0.32 when the color is purple p; the coefficient is 0.20 to 0.24 when the color is red r; and the coefficient is 0.17 to 0.21 when the color is blue b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a luminance correction method for correcting irradiation light luminance by multiplying irradiation light by a luminance correction coefficient.

In a display device such as a liquid crystal display device, in order to maintain good visibility of the screen when the ambient brightness changes, a detection unit that detects the amount of light in the surrounding environment and the amount of environmental light detected by the detection unit And storage means for storing brightness data including correction values for correcting the visibility, and displaying character / image information on the display device based on the brightness data corresponding to the ambient brightness detected by the detection means. (See, for example, Patent Document 1).
Japanese Patent Publication No. 7-74939

  The correction of the luminance in the display device described in Patent Document 1 adjusts the color visual sensitivity for each RGB in accordance with the amount of light in the surrounding environment, and the luminance (irradiation light luminance) multiplies the radiance by the visual sensitivity. Therefore, by adjusting the visibility, the same luminance can be obtained even if the amount of light in the surrounding environment changes. However, even when correction is made so that the same brightness is obtained in theory as described above, the “feel of brightness” actually felt by humans varies depending on the color of the light that is the object. . For example, when there is a light emitting object such as a signboard in which a red part and a white part are adjacent to each other, even if the luminance (irradiation light intensity) of the red part and the white part is set to be the same, Had the practical problem that the brightness felt different (the red part felt brighter).

  Therefore, the present invention is a luminance correction method for correcting the irradiation light luminance by multiplying the irradiation light by a luminance correction coefficient, and when a human views the irradiation light, regardless of the color of the irradiation light. An object of the present invention is to provide a luminance correction method capable of obtaining almost the same brightness feeling.

  In order to achieve the above object, the invention of claim 1 is a luminance correction method for correcting irradiation light luminance by multiplying irradiation light from a light emitting device that irradiates visible light by a luminance correction coefficient, wherein The luminance correction coefficient is reduced as the chromaticity of the irradiation light moves away from the reference white coordinate position in the CIE1931 chromaticity coordinates.

  According to a second aspect of the present invention, in the luminance correction method according to the first aspect, when the irradiation light is red, the luminance correction coefficient is 0.20 to 0.24.

  According to a third aspect of the present invention, in the luminance correction method according to the first aspect, the luminance correction coefficient is 0.37 to 0.45 when the irradiation light is orange.

  According to a fourth aspect of the present invention, in the luminance correction method according to the first aspect, when the irradiation light is yellow, the luminance correction coefficient is 0.66 to 0.80.

  According to a fifth aspect of the present invention, in the luminance correction method according to the first aspect, when the irradiation light is yellow-green, the luminance correction coefficient is 0.61 to 0.75.

  The invention of claim 6 is the brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.45 to 0.55 when the irradiation light is green.

  The invention according to claim 7 is the brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.54 to 0.66 when the irradiation light is blue-green.

  The invention according to claim 8 is the brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.17 to 0.21 when the irradiation light is blue.

  The invention of claim 9 is the brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.26 to 0.32 when the irradiation light is purple.

  The invention according to claim 10 is the brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.69 to 0.85 when the irradiation light is pink.

  According to an eleventh aspect of the present invention, in the luminance correction method according to the first aspect, when the irradiation light is light yellow, the luminance correction coefficient is 0.90 to 1.00.

  According to a twelfth aspect of the present invention, in the luminance correction method according to the first aspect, when the irradiation light is light blue, the luminance correction coefficient is 0.53 to 0.65.

  A thirteenth aspect of the present invention is the luminance correction method according to the first aspect, wherein the luminance correction coefficient is 0.58 to 0.70 when the irradiation light is light green.

  According to the present invention, the luminance correction coefficient is reduced as the chromaticity of the irradiated light moves away from the reference white coordinate position in the CIE 1931 chromaticity coordinates. Regardless of the color tone, almost the same brightness can be obtained.

  A luminance correction method according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows an iso-brightness curve entered on CIE 1931 chromaticity coordinates (hereinafter referred to as chromaticity coordinates). The iso-brightness curve is created by connecting points on the coordinates to which the same brightness correction coefficient can be applied. An experiment for obtaining luminance correction coefficients of representative colors such as red, blue, and green on the chromaticity coordinates will be described later. Note that the chromaticity coordinates were determined by the International Commission on Illumination (CIE) as a uniform display standard for colors in 1931. Only the color excluding brightness can be displayed on the xy coordinates, and visible light All colors (wavelengths of about 360-830 nm) are displayed as coordinates in the chevron region.

  For example, typical 12 colors (red, orange, yellow, yellow-green, green, blue-green, blue, purple, pink, light yellow, light blue, light green) for which the luminance correction coefficient was obtained in the experiment described later and white The position area on the degree coordinate is shown in FIG. Specifically, there are red r, green g, and blue b areas at three corners of the mountain area, and yellow y, yellow green yg, and orange m areas along the right side of the mountain area. There is a purple p region along the lower side, and there is a white w region slightly in the upper right position from the center of the mountain region. There is a pink tr region between white w and red r, a light green tg region and a bluish green bg region between white w and green g, and a light blue tb between white w and blue b. There are areas. There is a light yellow ty region at a position closest to the white w. The areas of the respective colors are based on the areas defined in JISZ9103.

  The brightness correction coefficient is 1.0 for the reference white w, and becomes smaller as the distance from the white w increases. In FIG. 1, the brightness correction coefficients are 0.8, 0.6, 0.4, Four iso-brightness curves L1, L2, L3, and L4 created by connecting points on the chromaticity coordinates having a value of 0.2 are shown. Therefore, the luminance correction coefficient for each color including light yellow ty inside the equal brightness curve L1 is 0.8 or more and 1 or less, and yellow y, yellow green yg, etc. between the equal brightness curves L1 and L2 etc. The brightness correction coefficient for each color including the color is 0.6 or more and 0.8 or less, and the brightness correction coefficient for each color including the orange m or the like between the equal brightness curves L2 and L3 is 0.4 or more and 0.6. The luminance correction coefficient for each color including a part of purple p and red r between the equal brightness curves L3 and L4 is 0.2 or more and 0.4 or less, and is outside the equal brightness curve L4. The luminance correction coefficient for each color including blue b in FIG.

  As described above, the luminance correction coefficient is based on white, and when a human sees an object (for example, a signboard) colored in an arbitrary color and illuminated by a light source such as a lamp, the brightness correction coefficient is received from the object. This is a luminance ratio for making the “feel of brightness” equal to the “feel of brightness” received when viewing a white reference object. For example, when the blue luminance correction coefficient at the position of chromaticity coordinates xb1 and yb1 is 0.2, the luminance of the blue colored sign is 0 with respect to the luminance of the white reference sign. .When set to 2 times, the “brightness” when viewed by humans for the first time is equivalent. Similarly, when the luminance correction coefficient for blue having the chromaticity coordinates of xb2 and yb2 in the same blue is 0.17, the luminance of the signboard colored in blue is the luminance of the white reference signboard. On the other hand, when the magnification is set to 0.17 times, “brightness” when viewed by humans is equivalent.

  Next, an experiment for deriving the luminance correction coefficient will be described with reference to FIGS. This experiment is a subjective evaluation experiment that is performed by measuring the illuminating light brightness when the human sense of brightness is equivalent. As shown in FIG. 2, the signboard device 1 used in the experiment is provided with a light source in a rectangular box 2 and a light-transmitting reference panel Ps (white) is attached to the left half of the front surface. A light-transmitting colored panel Pc is attached to the right half. The colored panel Pc can be removed from the box 2 and replaced with a panel of various colors. The light sources are arranged in a distributed manner in the box 2 so as to uniformly illuminate the left and right panels Ps and Pc, and are provided with a predetermined distance between each panel Ps and Pc. It is composed of an LED unit 3. The light source is configured such that the brightness (irradiation light intensity) of the left and right panels Ps and Pc can be adjusted separately and continuously by the subject operating the operation terminals 4s and 4c such as rotary switches. Yes.

  In the experiment, as shown in FIG. 3, the subject E sits at a position approximately 75 cm away from the signboard device 1 placed on the table, and the line of sight Ee of the subject E is approximately the center of the front surface of the signboard device 1. It was done so that it was the same height. The size of each panel Ps, Pc is 15 cm × 25 cm, and is set to have the same viewing angle (11 ° × 18 °) as an outdoor signboard of about 11 m wide installed at a position 50 m away from the observer. ing. In addition, there are 12 types of colored panels Pc (red, orange, yellow, yellow green, green, blue green, blue, purple, pink, light yellow, light blue, light green) as representative colors. An experiment for evaluating the brightness of Pc with the reference panel Ps was performed.

The procedure of the evaluation experiment is as follows. a) The subject E sits in the state shown in FIG. 3 with respect to the signboard apparatus 1 in the dark state of the laboratory, and adapts to darkness for 5 minutes. Thereafter, b) the light source on the reference panel Ps side was caused to emit light with a luminance of 150 cd / m ² , and the light source on the colored panel Pc side was caused to emit light with a luminance lower than 150 cd / m ² . c) The subject E observes both the panels Ps and Pc, and operates the operation terminal 4c so that the colored panel Pc has the same brightness (feeling of brightness) as the reference panel Ps, thereby increasing the luminance of the light source on the colored panel Pc side. Adjustments were made to increase gradually. d) The luminance and chromaticity of the colored panel Pc were measured using a color luminance meter in a state where the subject E felt that the brightness of both panels Ps and Pc were the same. A color luminance meter BM5A manufactured by Topcon Corporation was used as the color luminance meter. The above-described procedures a) to d) were repeated three times for the same subject, and the same content was tested for five subjects with subject E being changed.

Table 1 shows the experimental results for each colored panel. The luminance ratio in Table 1 is a value obtained by dividing the luminance of the colored panel Pc when the subject E determines that the colored panel Pc and the reference panel Ps (white) have the same brightness by the luminance of the reference panel Ps. Synonymous with luminance correction coefficient. In other words, the luminance ratio in Table 1 indicates that, for example, when the colored panel Pc is red, the same brightness was felt when the luminance of the red panel was 0.22 times the luminance of the reference panel Ps. It represents.

  The experimental results of the 12 colors are plotted on the chromaticity coordinates of FIG. The color coordinates of red R, orange M, yellow Y, yellow green YG, green G, blue green BG, blue B, purple P, pink TR, light yellow TY, light blue TB, and light green TG of the colored panel in this experiment are In the chromaticity coordinates of FIG. 1, red r, orange m, yellow y, yellow green yg, green g, blue green bg, blue b, purple p, pink tr, light yellow ty, light blue tb, and light green tg. include. In FIG. 1, the values in parentheses added to each color R, M, Y, YG, G, BG, B, P, TR, TY, TB, and TG round the luminance ratio (luminance correction coefficient) obtained by the experiment. Value.

Although it conducted same experimental set to 300 cd / ^{m 2} by changing the luminance of the reference panel Ps side of the light source to 150 cd / ^{m 2} in the above experiments, resulting luminance ratio (luminance correction coefficients), FIG. It was equivalent to that shown in Fig. 4, and it was not significant.

  An iso-brightness curve is created based on the luminance ratio (luminance correction coefficient) at a plurality of coordinate positions obtained by the above experiment. For example, the blue-green BG and the light blue TB in FIG. 1 have the same luminance ratio (brightness correction coefficient) of 0.6, so the coordinates of the blue-green BG and the light blue TB are connected and the brightness correction coefficient is 0.6. A slope curve L2 is created.

  A method for obtaining the irradiation light luminance of an object (signboard or the like) of an arbitrary color based on the chromaticity coordinates in which the equal brightness curve is written as described above will be described. The designer first determines the coordinates (x, y) of the color to be attached to the object, and determines the target brightness Lw when the color is white. Next, the designer obtains a luminance correction coefficient at coordinates (x, y) based on the chromaticity coordinates in FIG. At this time, when the coordinates (x, y) are between the equal brightness curves L1, L2, L3, L4, based on the distance from the two equal brightness curves sandwiching the coordinates (x, y). The brightness correction coefficient is prorated. If the calculated luminance correction coefficient is represented by k, it is given by the luminance Lc = k × Lw of the color at the coordinates (x, y).

For example, the designer selects (x, y) = (0.3, 0.25) as the color coordinates to be attached to the object, and the target luminance when the color is white is 150 cd / m. ^In the case of ² , since the coordinates (0.3, 0.25) are substantially on the equal brightness curve L3, the luminance correction coefficient k at the coordinates (0.3, 0.25) is 0.4. , Luminance Lc = 0.4 × 150 = 60 cd / m ² for the color of coordinates (0.3, 0.25). When the coordinates (x, y) are between the equal brightness curves Ln and Ln + 1, as described above, the distance between the coordinates (x, y) and the equal brightness curve Ln, and the coordinates (x, y) and The value of the luminance correction coefficient is prorated based on the ratio of the distance to the equal brightness curve Ln + 1.

  In addition, when the object is a signboard, a human being cannot identify a difference in luminance of about 10%, and thus it is possible to apply a luminance correction coefficient to be adopted with a width of about 10%. . In other words, by determining the color to be attached to the object, even if the luminance given to the object is calculated using an approximate luminance correction coefficient that matches the color, there is no substantial trouble.

  For example, when the color attached to the object is red, a value of 0.20 to 0.24 is set as the luminance correction coefficient based on the chromaticity coordinates of FIG. 1 without setting the accurate chromaticity coordinates of the red color. May be adopted. Similarly, when the color attached to the object is orange, the brightness correction coefficient is a value of 0.37 to 0.45, and when the color attached to the object is yellow, the brightness correction coefficient is 0.66 to 0.00. A value of 80, a brightness correction coefficient of 0.61 to 0.75 when the color attached to the object is yellow-green, and a brightness correction coefficient of 0.45 to 0 when the color attached to the object is green A value of .55, a luminance correction coefficient of 0.54 to 0.66 when the color attached to the object is blue-green, and a luminance correction coefficient of 0.17 to 0.67 when the color attached to the object is blue A value of 0.21, a value of 0.26 to 0.32 as the luminance correction coefficient when the color attached to the object is purple, and a value of 0.69 or more as the luminance correction coefficient when the color attached to the object is pink. When the value of 0.85 and the color attached to the object is light yellow, the brightness correction coefficient is set to 0. A value from 0 to 1.00, a brightness correction coefficient of 0.53 to 0.65 when the color attached to the object is light blue, and a brightness correction coefficient of 0 when the color attached to the object is light green A value of .58 to 0.70 may be employed. According to said method, the process of calculating the brightness | luminance of a target object can be simplified significantly.

When the illumination is performed so that the color panel is multiplied by the luminance correction coefficient, and when the illumination is performed at a predetermined luminance (for example, 150 cd / m ² ) that is not multiplied by the luminance correction coefficient, the coloring panel has a predetermined luminance. Table 2 shows the results of a sensory experiment on whether the feeling of brightness when compared with an illuminated white panel is the same.

  When illumination was performed so that the brightness was multiplied by the brightness correction coefficient, the subject felt that the brightness was the same as that of the white panel for all the 12 colored panels (the circle in the left column of Table 2). . On the other hand, in the case of a colored panel illuminated at a predetermined brightness that is not multiplied by the brightness correction coefficient, the subject feels that the brightness is different from that of the white panel in all the colored panels except the light yellow panel. (X in the right column in Table 2). For the light yellow panel, it was determined that the test subject was neither (△ mark in the right column in Table 2).

The figure which shows the CIE1931 chromaticity coordinate which shows the brightness | luminance correction coefficient in the brightness | luminance correction method which concerns on one Embodiment of this invention. The front view which shows the signboard apparatus used for the subjective evaluation experiment for calculating | requiring the brightness | luminance correction coefficient in the brightness | luminance correction method. The figure which shows arrangement | positioning of the apparatus of the subjective evaluation experiment for calculating | requiring the brightness | luminance correction coefficient in the brightness | luminance correction method.

Explanation of symbols

3 LED unit (light emitting device)
L1, L2, L3, L4, etc. Brightness curve r Red area m Orange area y Yellow area yg Yellow green area g Green area bg Blue green area b Blue area p Purple area tr Pink area ty Light yellow area tb Light blue area tg Light green area region

Claims (13)

A brightness correction method for correcting illumination light brightness by multiplying illumination light from a light emitting device that emits visible light by a brightness correction coefficient,
A luminance correction method, wherein the luminance correction coefficient is decreased as the chromaticity of the irradiation light moves away from a reference white coordinate position in CIE1931 chromaticity coordinates.   The luminance correction method according to claim 1, wherein the luminance correction coefficient is 0.20 to 0.24 when the irradiation light is red.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.37 to 0.45 when the irradiation light is orange.   The luminance correction method according to claim 1, wherein the luminance correction coefficient is 0.66 to 0.80 when the irradiation light is yellow.   The luminance correction method according to claim 1, wherein when the irradiation light is yellowish green, the luminance correction coefficient is 0.61 to 0.75.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.45 to 0.55 when the irradiation light is green.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.54 to 0.66 when the irradiation light is blue-green.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.17 to 0.21 when the irradiation light is blue.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.26 to 0.32 when the irradiation light is purple.   The luminance correction method according to claim 1, wherein the luminance correction coefficient is 0.69 to 0.85 when the irradiation light is pink.   The luminance correction method according to claim 1, wherein the luminance correction coefficient is 0.90 to 1.00 when the irradiation light is light yellow.   The luminance correction method according to claim 1, wherein the luminance correction coefficient is 0.53 to 0.65 when the irradiation light is light blue.   The brightness correction method according to claim 1, wherein the brightness correction coefficient is 0.58 to 0.70 when the irradiation light is light green.

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