KR20140146336A - Method for evaluating a luminance of a light source and lighting apparatus - Google Patents

Abstract

A brightness evaluation method according to an embodiment of the present invention includes the steps of; partitioning a light source into multiple cells; obtaining a plurality of first data by measuring the brightness of each cell; and deriving second data of multiple vertical cell sets classified by arranging the cells in the vertical direction and of multiple horizontal cell sets classified by arranging the cells in the horizontal directions; calculating the vertical and horizontal moving average values which are the average values of the vertical and horizontal cell sets′ second data; and obtaining a vertical ripple factor and a horizontal ripple factor form the difference between the second data of the vertical moving average and the horizontal moving average.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of evaluating brightness of a light source,

Embodiments relate to a method of evaluating luminance of a light source and a lighting apparatus.

GaN, and AlGaN are widely used in optoelectronics and electronic devices due to many advantages such as wide and easy bandgap energy adjustment.

Particularly, a light emitting device such as a light emitting diode or a laser diode using a semiconductor material of a group 3-5 or a group 2-6 compound semiconductor has been widely used in various fields such as red, green, blue, and ultraviolet It is possible to realize white light rays with high efficiency by using fluorescent material or color combination. Low power consumption compared to conventional light sources such as fluorescent lamps, incandescent lamps. Semi-permanent life span, fast response speed, safety. .

Therefore, a transmission module of the optical communication means, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, a white light emitting diode capable of replacing a fluorescent lamp or an incandescent lamp Lighting devices, automobile headlamps, and traffic lights.

A light emitting device package in which a plurality of light emitting elements are arranged in one unit may be used for the lighting device or the automobile head lamp.

Brightness is an important factor in the product characteristics of a lighting apparatus and a headlamp, and in particular, there is an increasing demand for a lighting apparatus and a headlamp which are excellent in uniformity of luminance.

The maximum value / minimum value of luminance data is used as a criterion for judging the uniformity of luminance of the lighting apparatus and the like at present. However, the maximum value / minimum value of the luminance data described above represents only the maximum value and the minimum value of the luminance of each region in one illuminator, and does not show the overall average value.

The average value of the overall luminance of the lighting apparatus and the deviation of each area are important factors for determining the uniformity of the luminance, but can not be expressed only by the maximum value and the minimum value of the luminance of each area.

In addition, since the luminance in the edge region of the lighting apparatus is relatively low, it can affect the minimum value of the luminance of each region described above.

An embodiment of the present invention attempts to determine the uniformity of luminance in the entire area of the lighting apparatus, thereby ensuring the luminance uniformity of the lighting apparatus.

A method of evaluating luminance of a light source of an embodiment of the present invention includes: dividing a light source into a plurality of cells; Measuring a luminance of each of a plurality of cells to obtain a plurality of first data; Deriving second data of a plurality of sets of vertical cells that are divided by arranging a plurality of cells in a vertical direction and a plurality of sets of horizontal cells that are arranged by horizontally arranging a plurality of cells; Calculating vertical moving average and horizontal moving average that averages second data of a plurality of vertical cell sets or second data of a plurality of horizontal cell sets; And obtaining a vertical ripple factor and a horizontal ripple factor from the difference between the vertical moving average or the horizontal moving average and the second data.

The method and apparatus for evaluating brightness of a light source according to an embodiment of the present invention divides an illumination apparatus into a plurality of cells to obtain a plurality of brightness data, and it is possible to evaluate the brightness accurately for each cell.

The method and apparatus for evaluating the luminance of the light source of one embodiment of the present invention can determine the difference in luminance for each cell by obtaining the moving average and the ripple factor based on the luminance data of a plurality of cells.

The method and apparatus for evaluating the luminance of the light source of one embodiment of the present invention is characterized in that the variance of the reflector obtained on the basis of the luminance data of the plurality of cells is obtained and the uniformity of the luminance of the illuminator is expressed by one parameter, .

The luminance evaluation method and the lighting apparatus of the light source of the embodiment of the present invention are characterized in that the drift is obtained in two directions of vertical and horizontal directions and the dispersion of the ripple effector derived from the release is used for the two movements, Can be high.

The method and apparatus for evaluating the luminance of a light source of an embodiment of the present invention is a method for evaluating luminance of a light source by deriving second data from the first data by removing data in a border region of the illumination apparatus, .

1 is a view showing an arrangement of light emitting device packages in a light source,
FIG. 2 is a view showing a region corresponding to first data of a light source in the light source of FIG. 1,
FIG. 3 is a diagram illustrating an arrangement direction of first data obtained in FIG. 2 for deriving the second data,
4 and 5 are diagrams for obtaining second data from the first data,
6 is a diagram of a method for excluding second data with low reliability,
7 to 10 show luminance distributions prepared using the luminance evaluation method of the light source of one embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

The terms first, second, etc. may be used to describe various elements, but such elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, the first contact may be referred to as a second contact, and likewise, the second contact may be referred to as a first contact, It is all contact, but not the same contact.

The terms used in the description of the invention are intended to be illustrative only of specific embodiments and are not intended to limit the invention. As used in the description of the invention and the appended claims, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. The use of an indication may denote either or both of the singular and plural forms of the term and vice versa.

It will be understood that the term "and / or" refers to and encompasses any and all possible combinations of one or more of the listed related items. The terms "comprises" and / or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements and / or components, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

The term " if, "as used herein refers to the term" when "or" upon ", or" in response to determining "or" Quot; and "to " Similarly, the phrase " when determined "or" when an " specified condition or event is detected " Quot; or "in response to detecting [the specified condition or event]. &Quot;

In the description of the embodiment according to the present invention, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a view showing an arrangement of light emitting device packages in a light source.

The light source 100 may be a lighting device, a head lamp of an automobile, or the like, and a plurality of light emitting devices 50 may be disposed on the substrate 10. The illuminating device includes at least one row of light emitting element arrays disposed on the substrate 10 and the substrate 10, and the light emitting element arrays can be arranged such that the brightness parameters to be derived below are minimized.

The light emitting device 50 may be a light emitting diode and the substrate 10 may be a printed circuit board capable of supplying current to the light emitting device 50.

The light emitting element 50 may be a vertical type light emitting element, a horizontal type light emitting element, and a flip chip type light emitting element.

The light emitting device may include a light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer.

The first conductive semiconductor layer may be formed of a compound semiconductor such as Group III-V or Group II-VI, and may be doped with a first conductive dopant. For example, the first conductive semiconductor layer may be a semiconductor material having a composition formula of Al _x In _y Ga _(1-xy) N (0? X? 1, 0? _Y? 1, 0? _X + AlGaN, GaN, InAlGaN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the first conductivity type semiconductor layer is an n-type semiconductor layer, the first conductivity type dopant may include n-type dopants such as Si, Ge, Sn, Se, and Te. The first conductivity type semiconductor layer may be formed as a single layer or a multilayer, but is not limited thereto.

When the light emitting device is ultraviolet (UV), deep ultraviolet (Deep UV), or nonpolar light emitting device, the first conductivity type semiconductor layer may include at least one of InAlGaN and AlGaN.

The active layer is disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer and includes a single well structure, a multiple well structure, a single quantum well structure, a multi quantum well (MQW) structure, A quantum dot structure or a quantum wire structure.

The active layer may include a well layer and a barrier layer such as AlGaN / AlGaN, InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP, but the present invention is not limited thereto. The well layer may be formed of a material having an energy band gap smaller than the energy band gap of the barrier layer.

The second conductivity type semiconductor layer may be formed of a semiconductor compound. The second conductivity type semiconductor layer may be formed of a compound semiconductor such as a group III-V or II-VI group, and may be doped with a second conductivity type dopant. The second conductivity type semiconductor layer may be a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? GaN AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the second conductivity type semiconductor layer is a p-type semiconductor layer, the second conductivity type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The second conductivity type semiconductor layer may be formed as a single layer or a multilayer, but is not limited thereto. If the light emitting device is ultraviolet (UV), deep ultraviolet (Deep UV), or nonpolar light emitting device, the second conductivity type semiconductor layer may include at least one of InAlGaN and AlGaN.

A concavo-convex structure may be formed on the surface of the first conductivity type semiconductor layer to improve light extraction efficiency of the light emitting device.

The above-described light emitting devices 50 may be arranged side by side in a horizontal direction and a vertical direction by aligning rows and columns on the substrate 10, but the intervals between the rows and the columns may not coincide or may be randomly arranged .

FIG. 2 is a diagram showing a region corresponding to first data of a light source in the light source of FIG. 1; FIG.

A method of evaluating luminance of a light source of an embodiment of the present invention includes a step of dividing a light source into a plurality of cells, a step of measuring a luminance of each of a plurality of cells to obtain a plurality of first data, Deriving second data of a plurality of vertical cell sets and a plurality of horizontal cell sets dividing a plurality of cells in a horizontal direction and dividing the second data of the plurality of vertical cell sets and the second data of the plurality of horizontal cell sets, Calculating vertical moving average and horizontal moving average over the data, and obtaining a vertical ripple factor and horizontal ripple factor from the difference between vertical moving average or horizontal moving average and second data.

As shown, when measuring the brightness of the light source and evaluating the brightness, the brightness of the light emitted from each of the plurality of cells of the substrate 10 when measuring the brightness of the light emitted from the plurality of light emitting devices disposed on the substrate 10 So that the first data can be obtained.

The luminance measuring method of the light source of one embodiment can divide the entire area of the light source emitting light into a plurality of cells, and can grasp the degree of light emission of all the cells.

The plurality of cells may be m * n from P ₁₁ to P _mn . it is possible to obtain a plurality of first data by measuring all the luminances of m * n cells. The number of first data may be m * n.

FIG. 3 is a diagram illustrating an arrangement direction of first data obtained in FIG. 2 for deriving the second data.

Referring to FIG. 3, a luminance evaluation method of a light source according to an exemplary embodiment includes a plurality of sets of vertical cells divided into a plurality of cells arranged in the vertical direction, and a plurality of sets of horizontal cells 2 < / RTI > data.

Figs. 4 and 5 are diagrams for obtaining second data from the first data. Fig.

Figure 4 shows the number of cells arranged in the horizontal direction in the first direction. A plurality of first data can be obtained by dividing the entire region of the substrate 10 into a plurality of cells and measuring the luminance of each of the plurality of cells. As shown in FIG. 3, the first data represents a luminance value corresponding to a total of n cells from P ₁₁ to P ₁₂ , ..., P _{1 (n-1)} , P _1n in one column Can be obtained. N first data in one column can be obtained by examining the brightness of all the cells, and m * n first data can be obtained by combining all the columns.

For example, the length d _{1 in} the horizontal direction and the length d _{2 in the} vertical direction of each cell P ₁₁ , ..., P _mn may all be 3 millimeters. Measuring the luminance of each of the cells _{(P 11, ...., P} mn) , each of the cells through the brightness measuring unit such as a camera capable of detecting an average brightness of the _{(P 11, ...., P} mn) .

4 is a diagram showing obtaining second data from the first data.

The amount of data may be excessively large when the number of the light emitting elements 50 is too large, and the luminance value of the region disposed at the edge is relatively low. Therefore, It can be excluded from the luminance evaluation because it may affect the minimum value.

The second data may be a value obtained by averaging a predetermined number of first data in a predetermined direction. For example, the second data may be a value obtained by averaging first data of five cells continuously arranged in the vertical direction or the horizontal direction, but the number of cells for obtaining the second data is not limited to this, can be different.

4 and 5, a luminance evaluation method of a light source according to an exemplary embodiment of the present invention includes: a plurality of vertical cell sets divided into a plurality of vertical cells by vertically arranging the plurality of cells; Of the horizontal cell set of the first set of horizontal cells.

The second data can be obtained from a set of cells including a predetermined number of cells continuously arranged in the horizontal direction or the vertical direction. The second data may be a value obtained by averaging the first data of a predetermined number of cells continuously arranged in the horizontal direction or the vertical direction.

The first data can be converted into second data corresponding to a plurality of unit cells. The luminance values of a plurality of adjacent first data may be averaged to determine second data corresponding to the unit cell.

For example, to derive the second data of a ₁ , a ₂ , 2P ₁₁ , 2P ₁₂ , ..., 2P _{1 (i-1)} , 2P _1i , b ₂ , b ₁ from one row in the horizontal direction . The second data obtained from the cells continuously arranged in the horizontal direction may be m * n.

In deriving the moving average, the second data with low reliability obtained from the cell located at the edge of the light source may be excluded. For example, if the second data is derived by averaging z first data, the second data derived based on less than z first data may not be utilized to derive the moving average.

As shown in FIG. 4, when z is 5, a1 and b1 derived by averaging the three first data and a2 and b2 derived by averaging the four first data are utilized to derive the moving average .

Referring to FIG. 5, second data can be derived from a predetermined number of cells continuously arranged in the vertical direction. For example, to derive the second data of a ₁ , a ₂ , 2P ₁₁ , 2P ₂₁ , ..., 2P _{(k-1) 1} , 2P _k1 , b ₂ , b ₁ from one row in the vertical direction .

In deriving the moving average, the second data with low reliability obtained from the cell located at the edge of the light source may be excluded. For example, if the second data is derived by averaging z first data, the second data derived based on less than z first data may not be utilized to derive the moving average.

As shown in FIG. 5, when z is 5, a1 and b1 derived by averaging three first data and a2 and b2 derived by averaging the four first data are utilized to derive moving average .

The average value of the luminance values (original data) of the five adjacent cells can be converted into the luminance value (New data) corresponding to a new unit cell and can be determined. The luminance value (Original data) before the conversion may be the first data, and the luminance value (New data) after the conversion may be the second data.

6 is a diagram of a method for excluding second data with low reliability.

Referring to FIG. 6, the luminance evaluation method of the light source of one embodiment may include a step of obtaining a moving average of the second data. For example, the step of obtaining moving average can calculate the vertical moving average and the horizontal moving average that averaged the second data of a plurality of vertical cell sets or the second data of a plurality of horizontal cell sets.

The step of calculating moving average can calculate the moving average except for a set of low-reliability vertical cells or a set of horizontal cells located at the outer periphery of the light source.

If the first data is a luminance value corresponding to an area having a length of 3 mm and a length of 3 mm respectively, the second data is a value obtained by averaging the first data of the adjacent area, and a part of the left and right n-1) / 2 may be ignored.

(N-1) / 2 cells from the edge of the light source, n is the number of vertical directions of the plurality of cells, n _ver, or the number of horizontal directions n _hor may be.

Obtaining a moving AVERAGE (M _a) may be a plurality. AVERAGE moving in a first method to obtain the (M _a), the moving AVERAGE (M _a) may be a value of the average value of average brightness of a set of cells derived from each set of cells second data.

In a second method to obtain a moving AVERAGE (M _aS), the may be a value averaged for the first scaled second data divided by the largest first data of the data that is the basis of the second data the second data. Thus, the scaled second data may be a value located between 0 and 1.

When moving average is obtained, the number of cell aggregates can be referred to as a moving average data number. The moving average data number may be an odd number, and if the moving average data number is an even number, the average luminance value of the number of sets of the number of cells that is one more than the moving average number may be derived as the second data. The moving average data number may vary depending on the length of the sample, that is, the length of the measured light source, which can be a moving average data number obtained by dividing the length of the sample by 25.

Moving average is the vertical moving average derived from the second data of the cell set of cells arranged in the vertical direction and the horizontal moving average derived from the second data of the cell set of cells arranged in the horizontal direction.

The brightness evaluation method of the light source of one embodiment may include obtaining a vertical ripple factor and a horizontal ripple factor from the difference between the vertical moving average or the horizontal moving average and the second data. A ripple factor is obtained from the above-mentioned moving average. The ripple factor (RF) can be defined by the following equation (1) or (2).

Equation 1

RF = (D _raw- M _a ) / M _a

Equation 2

RF = D _Sraw -M _aS

When obtained by the ripple factor (RF) when determined in the first method mentioned above, the moving AVERAGE (M _a), can be obtained by equation (1), moving AVERAGE second method mentioned above, the (M _aS), equation 2 can be obtained.

Obtaining a moving AVERAGE (M _a) may be a plurality. AVERAGE moving in a first method to obtain the (M _a), the moving AVERAGE (M _a) may be a value of the average value of average brightness of a set of cells derived from each set of cells second data. In a second method to obtain a moving AVERAGE (M _aS), the may be a value averaged for the first scaled second data divided by the largest first data of the data that is the basis of the second data the second data.

That is, the ripple factor RF may indicate how much the respective D _raw or D _{Sraw differs} from the moving _average (M _a or M _aS ), and D _raw may represent the average luminance value corresponding to each unit cell 2 < / RTI > data.

The ripple factor can be a vertical ripple factor derived from the throw in vertical moving and a horizontal ripple factor derived from the throw in horizontal moving.

If you obtain a ripple factor in equation (1), and vertical or horizontal ripple factor ripple factor (D _{a raw} -M) / M and _a, D a second _raw data set of cells in the vertical or horizontal cell group, M is _a vertical Moving average or horizontal moving average.

When the ripple factor is obtained from Equation (2), the vertical ripple factor or the horizontal ripple factor is D _Sraw -M _aS , D _Sraw is the second data of the vertical cell set or horizontal cell set, M _aS is the vertical moving average or horizontal moving It can be over-the-air.

The ripple factor RF corresponding to each unit cell may be greater than, equal to, or less than the moving average M _a .

Ripple factor may indicate the luminance of each of the unit cells of naneunji differ much from moving AVERAGE (M _a). However, since the ripple factor represents the + value or the negative value, even if the ripple factors of the unit cells in the illumination apparatus are averaged, + and - values are canceled to make it difficult to indicate whether the illumination apparatus is uniform as a whole.

The method of evaluating the luminance of the light source of one embodiment may include obtaining the variance of the vertical ripple factor and the horizontal ripple factor and comparing the variance of the vertical ripple factor and the variance of the horizontal ripple factor.

When the dispersion of the ripple factor RF is obtained, it is possible to confirm how much the luminance of each unit cell differs from the moving average (M _a ), thereby confirming the luminance uniformity in the lighting apparatus.

The dispersion of the ripple factor can be found from the following equation (2).

Equation 2

_{VRF = VAR [(D raw -M} a) / M a]

VRF is whether a small denotes the variance of the ripple factor, as described shows the respective D _raw an naneunji differ much from moving AVERAGE (M _a) As described, this time is greater each D _raw more moving AVERAGE (M _a), or .

The luminance evaluation method of the light source of one embodiment can determine the larger of the dispersion of the vertical ripple factor and the dispersion of the horizontal ripple factor as the luminance parameter.

7 to 10 show luminance distributions prepared using the luminance evaluation method of the light source of one embodiment.

Referring to FIGS. 7 to 10, data on the luminance of the light source measured in two dimensions can be confirmed through the luminance evaluation method of the light source.

Referring to FIG. 7, the difference in luminance of each light source can be detected through color and height. Referring to FIG. 8, the two-dimensional moving average derived from the second data can be confirmed. Referring to FIG. 9, raw data and two-dimensional moving average values are displayed together to confirm the averaged luminance value. Referring to FIG. 10, a ripple factor is derived from a two-dimensional moving average value You can see what you see.

In the brightness evaluation method of the light source described above, VRF which is dispersion of the ripple factor can be introduced to determine the uniformity of the luminance distribution in each region in the light source such as an illumination device. Then, in the conversion of the second data from the first data, the data of the edge region can be removed, and the influence of the low luminance value in the edge region can be excluded.

The luminance evaluation method of the light source described above is a method of calculating the luminance of a light source two-dimensionally to derive a luminance parameter, and in a case where a luminance parameter is calculated in a one- When the arranged light sources are not superimposed vertically, the error that can occur can be minimized.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that the constituent element can be implanted unless specifically stated to the contrary, But should be construed as further including other elements.

All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined.

Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible.

For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

10: substrate 50: light emitting element
100: Lighting device

Claims (13)

Dividing the light source into a plurality of cells;
Measuring a luminance of each of the plurality of cells to obtain a plurality of first data;
Deriving second data of a set of a plurality of vertical cells that are divided by arranging the plurality of cells in a vertical direction and a plurality of sets of horizontal cells that are arranged by horizontally arranging the plurality of cells;
Calculating vertical moving average and horizontal moving average that averages the second data of the plurality of sets of vertical cells or the second data of the plurality of sets of horizontal cells; And
And obtaining a vertical ripple factor and a horizontal ripple factor from the difference between the vertical moving average or the horizontal moving average and the second data. The method according to claim 1,
In the step of obtaining the ripple factor,
The vertical ripple factor or the ripple factor is the horizontal _{(D raw -M a) / M} a,
D _raw is a second data _height of the vertical cell set or the horizontal cell set, and M _a is the vertical moving average or the horizontal moving average. The method according to claim 1,
And obtaining second data scaled by dividing the second data by the first data having the largest first data as a basis of the second data. The method of claim 3,
Wherein the moving average is calculated,
And deriving a plurality of the scaled second data from the average to the moving image. 5. The method of claim 4,
In the step of obtaining the ripple factor,
_Wherein the vertical ripple factor or the horizontal ripple factor is D _Sraw- M _aS ,
D _Sraw is the scaled second data _height , and M _aS is the vertical moving average or the horizontal moving average. The method according to claim 1,
Deriving the second data,
Wherein the second data is an average value of the first data of the plurality of cells included in the set of vertical cells or the set of horizontal cells. The method according to claim 1,
And obtaining a dispersion of the vertical ripple factor and the horizontal ripple factor. 8. The method of claim 7,
And comparing the variance of the vertical ripple factor with the magnitude of the variance of the horizontal ripple factor. 9. The method of claim 8,
Wherein the luminance parameter is larger than the variance of the vertical ripple factor and the variance of the horizontal ripple factor. The method according to claim 1,
Calculating the moving average,
And calculating the moving average by excluding the set of vertical cells or the set of horizontal cells having a low reliability at an outer edge of the light source. 11. The method of claim 10,
The set of vertical cells or the set of horizontal cells having the low reliability is a set of cells including (n-1) / 2 cells from the edge of the light source,
Wherein n is the number of the plurality of cells in the vertical direction, n _ver, or the number of the horizontal direction is n _hor . The method according to claim 1,
The step of partitioning the cells comprises:
And dividing a plurality of regions each having a size of a horizontal direction and a vertical direction of 3 millimeters into the cells. Board;
And at least one row of light emitting element arrays disposed on the substrate,
Wherein the light emitting element array is arranged such that the luminance parameter of the ninth aspect is minimized.

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