JP6020559B2 - Method for evaluating color unevenness of surface light emitter, evaluation apparatus, and evaluation program - Google Patents

Description

  The present invention relates to a method for evaluating color unevenness of a surface light emitter, an evaluation apparatus, and an evaluation program.

Surface light emitters used as backlights for various displays, display boards such as signboards and emergency lights, and light sources such as lighting have attracted attention in recent years because they have many excellent features such as high brightness, high efficiency, thinness, and light weight. ing.
Among such surface light emitters, organic electroluminescence elements (organic EL elements) that emit light by using electrical energy from positive and negative electrodes using organic materials can emit light at a low voltage of several volts to several tens of volts. In particular, it is attracting attention because it is a thin-film type complete solid-state device and saves space.

  When such a surface light emitter emits light due to a difference in film thickness in a light emitting region, display unevenness such as luminance unevenness and color unevenness may be observed. Therefore, in the production process, a method for uniformly evaluating these display unevenness is required.

For example, as a method for evaluating luminance unevenness, there is a method for evaluating luminance unevenness from the difference between the maximum value and the minimum value of the luminance in the light emitting region. However, in this evaluation method, even if the evaluation result (difference between the maximum value and the minimum value of the luminance) is the same, luminance unevenness is conspicuous depending on the method of the luminance distribution in the numerical range, and as an evaluation method, Not enough.
Therefore, a technique for evaluating luminance unevenness by dividing the light emitting area into 13 blocks and measuring the light emission luminance for each block is disclosed (see Non-Patent Document 1). In this non-patent document 1, when evaluating the luminance unevenness, a more strict evaluation of the luminance unevenness is possible by taking into account the distance between the blocks.

Thorsten Gerloff et al. , OLED100. eu NEWSLETTER, FEBRUARY 2010

  However, no report has yet been made on a method for evaluating color unevenness of a surface light emitter as described above.

  Therefore, a main object of the present invention is to provide a method for evaluating color unevenness of a surface light emitter, and another object is to provide an evaluation apparatus and an evaluation program.

In order to solve the above problems, according to one aspect of the present invention,
Dividing the light emitting region of the surface light emitter into a plurality of blocks;
Measuring tristimulus values for each block;
Calculating a lightness index and a chromaticness index from the tristimulus values;
Calculating a color difference ΔEab _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (1), and calculating a distance d _ij using the following formula (2):
Calculating the color unevenness index C _d of the surface light emitter from the color difference ΔEab _ij and the distance d _ij using the following equation (3):
A method for evaluating color unevenness of a surface light emitter is provided.

In equation (1), “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “a _j ” and “b _j ” represent the chromaticness index of the block at position j.

  In Expression (2), “h” and “w” indicate that the block at position j is at the position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. , “M” and “n” respectively represent the number of divisions in the vertical and horizontal directions of the light emitting region.

In equation (3), “ΔEab _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided.

Furthermore, according to another aspect of the invention,
Dividing the light emitting region of the surface light emitter into a plurality of blocks;
Measuring tristimulus values for each block;
Calculating a lightness index and a chromaticness index from the tristimulus values;
Calculating a color difference ΔE _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (4), and calculating a distance d _ij using the following formula (2):
Calculating the color unevenness index E _d of the surface light emitter from the color difference ΔE _ij and the distance d _ij using the following equation (5);
A method for evaluating color unevenness of a surface light emitter is provided.

In Expression (4), “L _i ” represents the lightness index of the block at position i, “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “L _j ” represents the position at position j. The lightness index of the block is represented, and “a _j ” and “b _j ” represent the chromaticness index of the block at position j.

  In Expression (2), “h” and “w” indicate that the block at position j is at the position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. , “M” and “n” respectively represent the number of divisions in the vertical and horizontal directions of the light emitting region.

In equation (5), “ΔE _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided.

  ADVANTAGE OF THE INVENTION According to this invention, the evaluation method of the color nonuniformity of a surface light-emitting body can be provided, and also an evaluation apparatus and an evaluation program can be provided.

It is a block diagram which shows schematic structure of an evaluation apparatus. It is a flowchart for demonstrating operation | movement of an evaluation apparatus. It is a schematic diagram which shows an example of the division | segmentation of a light emission area | region. It is a flowchart for demonstrating operation | movement of an evaluation apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[First Embodiment]
An example of the surface light emitter according to the present invention is an organic EL element.
The organic EL element includes a support substrate, an electrode, an organic layer having various functions, and the like. Although the specific example of the preferable structure of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / cathode (ii) Anode / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron Transport layer / electron injection layer / cathode (iii) anode / hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / cathode (iv) anode / hole injection layer / Hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode

<Evaluation equipment>
As an example of an apparatus for evaluating color unevenness of a surface light emitter, a color unevenness measuring apparatus 1 is used as shown in FIG.
The color unevenness measuring apparatus 1 mainly includes a control unit 10, a measurement unit 20, a storage unit 30, an input unit 40, and an output unit 50.

The control unit 10 is mainly composed of a CPU 12 and a RAM 14.
The CPU 12 centrally controls each part of the color unevenness measuring apparatus 1. The CPU 12 develops a program designated from the system program and various application programs stored in the storage unit 30 in the RAM 14 and executes various processes in cooperation with the program expanded in the RAM 14. For example, the CPU 12 functions as a data creation unit and a determination unit by executing a measurement process described later in cooperation with a program.
The RAM 14 has a program development area that is developed when the CPU 12 executes a program, a work area that temporarily stores input data input from the input unit 40, various processing results, and the like.

  The measuring unit 20 includes, for example, three sensors 22 having spectral sensitivity corresponding to the human eye and a sensitivity substantially the same as a so-called color matching function, and the sensor 22 directly measures tristimulus values X, Y, and Z. .

The storage unit 30 is configured by a read-only semiconductor memory such as a ROM 32 and is a memory that stores programs and data for realizing various functions of the color unevenness measuring apparatus 1.
The storage unit 30 has a recording medium (not shown) in which programs and data are stored in advance, and this recording medium can be fixedly or detachably mounted on the storage unit 30. Each program is stored in the form of a readable program code, and the CPU 12 sequentially executes operations according to the program code. An evaluation program, which will be described later, is also stored in the recording medium as an execution of the evaluation method.
The storage unit 30 may be configured with an HDD or the like.

  The input unit 40 is a device for inputting commands (commands), data, and the like to the color unevenness measuring apparatus 1 from the outside, and includes, for example, a touch panel and a keyboard.

The output unit 50 is a device for outputting the command and data input from the input unit 40 and the calculation result of the control unit 10. For example, a display such as an LCD (Liquid Crystal Display) or an ELD (Electro Luminescence Display). And a printing device such as a printer.
Moreover, the output part 50 is good also as an aspect which comprises a touch panel integrally with the input part 40. FIG.

"Evaluation method"
FIG. 2 is a flowchart showing a flow of measurement processing in which the control unit 10 reads the evaluation program from the storage unit 30 and executes it. The evaluation program is stored in the recording medium and executes steps S1 to S7 described later.

  In step S <b> 1, when a power switch (not shown) is turned on, the color unevenness measuring apparatus 1 is activated and necessary parts are initialized by the control unit 10.

In step S <b> 2, when the control unit 10 receives a command to start measurement from the input unit 40, the control unit 10 divides the measurement range of the light emitting region of the surface light emitter according to the number of blocks input in advance by the user.
The total block number l can be arbitrarily set. For example, the user inputs the vertical division number m and the horizontal division number n of the light emitting area at the input unit 40. When the vertical and horizontal directions are divided into 5 (m = 5, n = 5), the total number of blocks l is 25 as shown in FIG.
Each block is assigned a block number i (= 1 to 25) from the upper left to the lower right, for example.
In addition, in FIG. 3, although the square shape was demonstrated as an example as a shape of a light emission area | region and a block, it is not limited to this, For example, the light emission area which exhibits a rectangular shape is made into a square shape or a rectangular block. It may be divided.

In step S3, tristimulus values X, Y, and Z are measured for each block divided as described above.
Specifically, light emitted from the light source and reflected for each block of the measurement object is received by the three sensors 22. Based on this data, the CPU 12 performs conversion processing into the CIE 1931XYZ color system, and calculates tristimulus values X, Y, and Z for each block.
In the present invention, the tristimulus value is a two-degree visual field tristimulus value.

In step S4, the tristimulus values X, Y, and Z are converted into CIE1976L ^* a ^* b ^* color system values.

Specifically, first, the maximum value of the measured stimulus value Y is set to 100, and the other tristimulus values X, Y, and Z are normalized based on the conversion ratio.
Next, the tristimulus values X, Y, and Z of the black body radiation having the same color temperature as the correlated color temperature at the maximum value of the measured stimulus value Y are normalized so that Y becomes 100, and this standard The converted values are Xn, Yn, and Zn, respectively.
The tristimulus values of black body radiation corresponding to the color temperature are stored in the storage unit 30 as a data table.
By substituting the values calculated as described above into the following formulas (6) to (8), the lightness index L ^* and the chromaticness index a ^* , b ^* are calculated.

In step S5, the color difference ΔEab _ij and the distance d _ij between the blocks at arbitrarily selected positions i and j are calculated using the following equations (1) and (2).

In equation (1), “a _i ” and “b _i ” represent the chromaticness index at position i, and “a _j ” and “b _j ” represent the chromaticness index at position j.

  In Expression (2), “h” and “w” indicate that the block at position j is at the position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. , “M” and “n” respectively represent the number of divisions in the vertical and horizontal directions of the light emitting region.

In step S6, using the calculated distance _{d ij} and the color difference AEab _ij, it calculates the color non-uniformity index _{C d} in the light emitting region of the surface light emitter. The color unevenness index _Cd is obtained by the following formula (3).

In Expression (3), “ΔEab _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and “l” represents the total number of blocks in the light emitting region.

In step S < _b > 7, the control unit 10 performs stepwise evaluation of the color unevenness of the surface light emitter together with the color unevenness index Cd, and outputs the evaluation result to the output unit 50.

The stage evaluation is performed with reference to an evaluation table (not shown) stored in the storage unit 30.
For example, if C _d ≦ 30, ◎, 30 <C _d ≦ 80, ◯, 80 <C _d ≦ 120, Δ, 120 <C _d , ×.

According to the present embodiment described above, when evaluating the color unevenness of the light emitting area of the surface light emitter, the light emitting area is divided into a plurality of blocks, and the color difference between the two blocks causing the color unevenness is corrected by the distance. Therefore, color unevenness can be more strictly evaluated.
For example, when the color difference between two points is large, the color unevenness when visually observed feels stronger as the distance is shorter. In the present invention, as can be seen from the above equation (3), the color difference is corrected by the distance. That is, when considering the two blocks having a large color difference, the greater the distance between the blocks is large to reduce the influence of the color non-uniformity index C _d, the influence of the higher color non-uniformity index C _d the distance between the blocks is small in the opposite By increasing the value, it becomes possible to numerically evaluate the color unevenness perceived by human eyes.

[Second Embodiment]
The second embodiment is different from the first embodiment mainly in the following points.

"Evaluation method"
FIG. 4 is a flowchart showing a flow of measurement processing in which the control unit 10 reads out and executes an evaluation program from the storage unit 30. The evaluation program is stored in the recording medium and executes steps S1 to S4 and S8 to 10.

In step S8, a color difference ΔE _ij and a distance d _ij between arbitrarily selected blocks at position i and position j are calculated using the following equations (4) and (2).

In Equation (4), “L _i ” represents the lightness index at position i, “a _i ” and “b _i ” represent the chromaticness index at position i, and “L _j ” represents the lightness index at position j. , “A _j ” and “b _j ” represent the chromaticness index at position j.

  In Expression (2), “h” and “w” indicate that the block at position j is at the position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. , “M” and “n” respectively represent the number of divisions in the vertical and horizontal directions of the light emitting region.

In step S9, the color unevenness index E _d in the light emitting region of the surface light emitter is calculated using the calculated color difference ΔE _ij and the distance d _ij . The color unevenness index _Ed is determined by the following formula (5).

In equation (5), “ΔE _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and “l” represents the total number of blocks in the light emitting area.

In step S < _b > 10, the control unit 10 performs stepwise evaluation of the color unevenness of the surface light emitter together with the color unevenness index Ed, and outputs the evaluation result to the output unit 50.

The stage evaluation is performed with reference to an evaluation table (not shown) stored in the storage unit 30.
For example, Ｅ if E _d ≦ 120, ◯ if 120 <E _d ≦ 160, Δ if 160 <E _d ≦ 200, and × if 200 <E _d .

  According to the above embodiment, the same effect as that of the first embodiment can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Measurement of sample>
(1) Measurement of color unevenness index of panel 101 Panel 101 which is a surface light source was prepared, and tristimulus values X, Y, and Z of panel 101 were measured using the color unevenness measuring apparatus of FIG. In the measurement, the light emitting area of the panel 101 was divided into 5 parts in the vertical direction and 5 parts in the horizontal direction, and the total number of blocks was 25 (see FIG. 3).
For the measurement, a two-dimensional color luminance meter CA-2000 (manufactured by Konica Minolta Sensing) was used, and the measurement environment temperature (Ta) was 23 ° C. As a driving power source for the panel 101, a DC voltage / current source 6243 (manufactured by ADC Corporation) was used, and the driving current was set to 350 mA.
The measurement results are shown in Table 1.

Subsequently, from the tristimulus values X, Y, and Z, the lightness index L ^* and the chromaticness indices a ^* and b ^* were calculated.

First, normalization was performed so that the stimulus value Y of the block 5 indicating the maximum value of the stimulus value Y was 100.
Next, the X, Y, and Z values of the black body radiation having the same color temperature as the correlated color temperature 2418K of the block 5 are normalized so that the Y value becomes 100, and these are normalized to Xn (= 117), Yn (= 100), Zn (= 24) was used.
By substituting these Xn, Yn and Zn into the above formulas (6) to (8), the lightness index L ^* and the chromaticness indices a ^* and b ^* were calculated.

Next, a color difference ΔEab _ij and a distance d _ij between two arbitrarily selected blocks were calculated using the above formulas (1) and (2).

Next, the color unevenness index _Cd was calculated using the above formula (3).
As a result, the color unevenness index _Cd was 20.

(2) Measurement of color unevenness index of panel 102 In the measurement of the tristimulus value of panel 101, panel 102 is similarly processed except that the total number of blocks is 81 (= 9 × 9 in width) and the drive current is 280 mA. The tristimulus values were measured.
The measurement results are shown in Table 2.

From the tristimulus values, in the same manner as panel 101, and calculates the color non-uniformity index C _d of the panel 102.
As a result, the color unevenness index _Cd was 42.
In the panel 102, Xn = 102, Yn = 100, and Zn = 59.

(3) Measurement of color unevenness index of panel 103 In the measurement of the tristimulus value of panel 101, the tristimulus value of panel 103 was measured in the same manner except that the driving current was set to 100 mA.
Table 3 shows the measurement results.

From the tristimulus values, in the same manner as panel 101, and calculates the color non-uniformity index C _d of the panel 103.
As a result, the color unevenness index _Cd was 164.
In the panel 103, Xn = 98, Yn = 100, and Zn = 83.

<Evaluation of sample>
(1) Visual color unevenness evaluation Visual evaluation was performed on the panels 101 to 103 according to the following criteria.
The evaluation results are shown in Table 4.

◎: No color unevenness ○: Color unevenness is not concerned △: Color unevenness is worrisome ×: Color unevenness is very worrisome

(2) Summary As can be seen from Table 4, there is a correlation between the color unevenness index _Cd and the result of visual color unevenness evaluation.
From the above, by dividing the light-emitting region into a plurality of blocks, the use of color non-uniformity index C _d is calculated from the color difference and the distance between the blocks is found to be useful for evaluation of color unevenness.

<Measurement of sample>
(1) Measurement of color unevenness index of panel 101 In the measurement of panel 101 of Example 1, the color difference and the color unevenness index were calculated in the same manner except that the above expressions (4) and (5) were used, respectively. The panel 101 was measured.
As a result, the color unevenness index _Ed was 106.

(2) Measurement of color unevenness index of panel 102 In the measurement of panel 102 of Example 1, the color difference and the color unevenness index were calculated in the same manner except that the above expressions (4) and (5) were used, respectively. The panel 102 was measured.
As a result, the color unevenness index _Ed was 139.

(3) Measurement of color unevenness index of panel 103 In the measurement of panel 103 of Example 1, the color difference and the color unevenness index were calculated in the same manner except that the above expressions (4) and (5) were used, respectively. The panel 103 was measured.
As a result, the color unevenness index _Ed was 265.

<Evaluation of sample>
(1) Visual color unevenness evaluation Visual evaluation was performed on the panels 101 to 103 according to the following criteria.
The evaluation results are shown in Table 5.

◎: No color unevenness ○: Color unevenness is not concerned △: Color unevenness is worrisome ×: Color unevenness is very worrisome

(2) Summary As can be seen from Table 5, there is a correlation between the color unevenness index _Ed and the result of visual color unevenness evaluation.
From the above, by dividing the light-emitting region into a plurality of blocks, the use of color non-uniformity index E _d calculated from the color difference and the distance between the blocks is found to be useful for evaluation of color unevenness.

  The present invention can be suitably used for more strictly evaluating color unevenness of a surface light emitter.

1 color unevenness measuring device 10 control unit 12 CPU
14 RAM
20 Measurement unit 22 Sensor 30 Storage unit 32 ROM
40 Input unit 50 Output unit

Claims (6)

Dividing the light emitting region of the surface light emitter into a plurality of blocks;
Measuring tristimulus values for each block;
Calculating a lightness index and a chromaticness index from the tristimulus values;
Calculating a color difference ΔEab _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (1), and calculating a distance d _ij using the following formula (2):
Calculating the color unevenness index C _d of the surface light emitter from the color difference ΔEab _ij and the distance d _ij using the following equation (3):
A method for evaluating color unevenness of a surface light emitter.

[In Expression (1), “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “a _j ” and “b _j ” represent the chromaticness index of the block at position j. . ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (3), “ΔEab _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ] A measurement unit that measures tristimulus values for each block of the light emitting region of the surface light emitter divided into a plurality of parts,
A brightness index and a chromaticness index are calculated from the tristimulus values, and a color difference ΔEab _ij between two arbitrarily selected blocks is calculated from the chromaticness index using the following formula (1), and a distance d _{a controller} that calculates _ij using the following equation (2), and calculates the color unevenness index C _d of the surface light emitter using the following equation (3) from the color difference ΔEab _ij and the distance d _ij :
A color unevenness evaluation apparatus for a surface light emitter, comprising:

[In Expression (1), “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “a _j ” and “b _j ” represent the chromaticness index of the block at position j. . ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (3), “ΔEab _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ] In a computer as a color unevenness evaluation device for surface light emitters,
A function of dividing the light emitting area of the surface light emitter into a plurality of blocks;
A function of measuring tristimulus values for each block;
A function of calculating a brightness index and a chromaticness index from the tristimulus values;
A function of calculating a color difference ΔEab _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (1), and calculating a distance d _ij using the following formula (2):
A function of calculating a color unevenness index C _d of the surface light emitter from the color difference ΔEab _ij and the distance d _ij using the following formula (3):
A nonuniformity evaluation program for a surface light emitter characterized by realizing the above.

[In Expression (1), “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “a _j ” and “b _j ” represent the chromaticness index of the block at position j. . ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (3), “ΔEab _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ] Dividing the light emitting region of the surface light emitter into a plurality of blocks;
Measuring tristimulus values for each block;
Calculating a lightness index and a chromaticness index from the tristimulus values;
Calculating a color difference ΔE _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (4), and calculating a distance d _ij using the following formula (2):
Calculating the color unevenness index E _d of the surface light emitter from the color difference ΔE _ij and the distance d _ij using the following equation (5);
A method for evaluating color unevenness of a surface light emitter.

[In Expression (4), “L _i ” represents the lightness index of the block at position i, “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “L _j ” represents position j “A _j ” and “b _j ” represent the chromaticness index of the block at position j. ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (5), “ΔE _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ] A measurement unit that measures tristimulus values for each block of the light emitting region of the surface light emitter divided into a plurality of parts,
A brightness index and a chromaticness index are calculated from the tristimulus values, and a color difference ΔE _ij between two arbitrarily selected blocks is calculated from the chromaticness index using the following equation (4), and a distance d _{a controller} that calculates _ij using the following equation (2), and calculates the color unevenness index E _d of the surface light emitter using the following equation (5) from the color difference ΔE _ij and the distance d _ij :
A color unevenness evaluation apparatus for a surface light emitter, comprising:

[In Expression (4), “L _i ” represents the lightness index of the block at position i, “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “L _j ” represents position j “A _j ” and “b _j ” represent the chromaticness index of the block at position j. ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (5), “ΔE _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ] In a computer as a color unevenness evaluation device for surface light emitters,
A function of dividing the light emitting area of the surface light emitter into a plurality of blocks;
A function of measuring tristimulus values for each block;
A function of calculating a brightness index and a chromaticness index from the tristimulus values;
A function of calculating a color difference ΔE _ij between two arbitrarily selected blocks from the chromaticness index using the following formula (4), and calculating a distance d _ij using the following formula (2):
A function for calculating a color unevenness index E _d of the surface light emitter from the color difference ΔE _ij and the distance d _ij using the following equation (5):
A nonuniformity evaluation program for a surface light emitter characterized by realizing the above.

[In Expression (4), “L _i ” represents the lightness index of the block at position i, “a _i ” and “b _i ” represent the chromaticness index of the block at position i, and “L _j ” represents position j “A _j ” and “b _j ” represent the chromaticness index of the block at position j. ]

[In Expression (2), “h” and “w” indicate that the block at position j is at a position of h blocks in the vertical direction and w blocks in the horizontal direction with respect to the block at position i. “M” and “n” represent the number of divisions in the vertical and horizontal directions of the light emitting region, respectively. ]

[In Expression (5), “ΔE _ij ” and “d _ij ” represent the color difference and distance between the blocks at position i and position j, respectively, and l represents the number of blocks into which the light emitting area is divided. ]

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