JP3896895B2 - Light guide plate for surface light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light plate which uniformly emits light from a light- emitting surface and can suppress generation of emission lines. SOLUTION: This light guide pate has an emitting plane and a reflection plane provided opposite to each other, and a plurality of dots are formed on the reflection plane so that the light inputted from a light source provided on the one end surface or from light sources provided on the two end surfaces opposite to each other is emitted uniformly from the light-emitting plane. The dots are arranged so as to form a strip-shaped region defined as a region which has a fixed distribution density. Within each strip-shaped region, a plurality of vertical lines which is directed to adjoining strip regions are formed at approximately equal intervals while, between the adjoining strip-shaped regions, the interval of vertical lines formed of the dots are set so as to be different from each other.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light guide plate of a surface light emitting device for spreading light from a light source over the entire light emitting surface for output.
[0002]
[Prior art]
2. Description of the Related Art In recent years, surface light emitting devices that emit light from LED chips, which are point light sources, in a planar shape are used as light sources such as liquid crystal backlights. This surface light emitting device is configured to allow light from one or more light emitting diodes to enter from one end surface of a light guide plate having opposing main surfaces and to emit light from the entire one main surface of the light guide plate. The
That is, as shown in the plan view of FIG. 20, the outer frame 903 has a first main surface and a second main surface and is made of a transparent resin, and faces the end surface of the light guide plate 901. A light-emitting diode 902 provided on the second main surface side of the light guide plate, and a reflector (not shown) provided on the second main surface side of the light guide plate. Light from the entire main surface
[0003]
In the surface light emitting device configured as described above, the light output from the light emitting diode 902 decreases as it propagates through the light guide plate 901, and the amount of light decreases as it moves away from the light source. A light diffusing dot pattern is formed on the main surface of the surface to obtain uniform surface light emission. This light diffusing dot pattern increases the area occupied by the light diffusing dots sequentially by increasing the dot density or the area of each dot as the distance from the light source increases, so that the luminance in the light emitting surface is made uniform. .
FIG. 21 is a plan view showing a light diffusing dot pattern on the light guide plate reflecting surface disclosed in Japanese Patent Application Laid-Open No. 8-271893. In this example, the area of the dots 102 is sequentially increased as the distance from the light source 101 increases. Thus, the ratio of the area occupied by the light diffusing dots is gradually increased as the distance from the light source increases.
[0004]
[Problems to be solved by the invention]
However, the conventional light diffusing dot pattern shown in FIG. 21 has a problem that bright lines are generated due to the arrangement of the light diffusing dots.
[0005]
Therefore, an object of the present invention is to provide a light guide plate that can emit light uniformly from a light emitting surface and can suppress generation of bright lines.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, according to the present inventionsurfaceThe light guide plate of the light emitting device has an emission surface and a reflection surface facing each other, and reflects the light input from a light source provided on one end surface or two opposite end surfaces so that the light is uniformly emitted from the emission surface. In the light guide plate of the surface light emitting device in which a plurality of dots are formed on the surface, the dots are arranged so that a band-shaped region defined as a region having a certain distribution density is formed,The distribution density of the band-like region is set to sequentially increase by a certain amount as the distance from the light source is increased according to the attenuation amount of light input from the light source,In each of the band-like regions, a plurality of vertical lines in the direction toward the adjacent band-like region are formed at substantially equal intervals by arranging the dots, and the interval between the vertical lines formed by the dots in each of the band-like regions is The adjacent band-like regions are set to be different from each other.
  According to the present invention configured as described abovesurfaceIn the light guide plate of the light emitting device, the vertical lines are spaced apart from each other between the adjacent strip-like regions, so that the vertical lines do not form one straight line over a long distance, and bright lines are generated. Can be prevented.
  In addition, since the distribution density of the band-like region is set so as to sequentially increase by a certain amount as the distance from the light source increases according to the attenuation amount of light input from the light source, uniform surface light emission is possible.
[0008]
  Further, according to the present inventionsurfaceIn the light guide plate of the light emitting device, the dots are arranged so that a plurality of horizontal lines orthogonal to the vertical lines are formed in each of the band-shaped regions, and the interval between the vertical lines and the interval between the horizontal lines are set. You may make it set based on the distribution density of the dot in the strip | belt-shaped area | region.
[0010]
  Further, the above according to the present inventionsurfaceIn the light guide plate of the light emitting device, the aboveYou may comprise so that the said dot may be arrange | positioned at random so that it may become the density set according to the attenuation amount of light in a part of reflective surface located in the both sides of the end surface provided with the light source.
[0011]
  Furthermore, the above according to the present inventionsurfaceIn the light guide plate of the light emitting device, the light sourceNeighborhoodThe dots may be arranged at random in a part of the reflecting surface located at a position such that the dots have a density set according to the amount of attenuation of light.
[0012]
  Furthermore, according to the present inventionsurfaceIn the light guide plate of the light emitting device, it is preferable that each of the dots has a concave portion and a convex portion, whereby light can be scattered more effectively at each dot.
[0013]
Each dot may be constituted by a convex part and a concave part formed around the convex part, or may be constituted by a concave part and a convex part formed around the concave part.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a light guide plate of a surface light emitting device according to an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
The light guide plate of the first embodiment forms an input from a light source by forming a large number of dots so as to satisfy a predetermined distribution on a reflection surface that is the other main surface opposite to an emission surface that is one main surface. The light guide plate of the surface light emitting device is configured such that the emitted light is uniformly emitted from the emission surface, and the predetermined distribution is realized by a dot pattern unique to the present application.
That is, in the light guide plate of the first embodiment, dots are formed in the main part of the reflection surface except for the corners 52a and 52b located on both sides of the end surface where the light source 10 is provided on the reflection surface as follows. Yes.
1 is a plan view showing the distribution of dots formed on the reflection surface of the light guide plate, and FIG. 2 is an enlarged view of a part of FIG. 1 (part indicated by reference numeral 51).
[0015]
(Strip-shaped area with constant dot density)
First, on the reflecting surface of the first embodiment, as shown in FIG. 2, the dots are arranged such that a region having a constant dot density is formed in a band shape.
Each strip region R formed in this strip shape_k(K = 1, 2, 3,..., N) is defined by setting a boundary every time the dot density increases by ΔDy in the dot density curve C1 shown in FIG.
Each strip region R_kThe dot density is, for example, a dot density D that is an average value of the maximum dot density and the minimum dot density on the dot density curve C1 corresponding to each region._kEach strip region R_kInside, the dot density is constant (its band-like region R_kThe dot density is D everywhere in_kIt is. ) To form dots.
That is, the strip region R_kIs defined as a region having a constant distribution density.
In the first embodiment, each strip region R_kWidth ΔLx_kIs set sufficiently small compared to the length of the light guide plate, and each strip region R_kIn this case, even if the dot density is set constant, the dot density of the first embodiment can be regarded as substantially equivalent to that set according to the dot density curve C1 of FIG.
[0016]
(Each strip region R_kDot array)
Each strip region R of the first embodiment_kAs shown in FIG. 2, the dots are vertical lines 1 in the direction toward the adjacent belt-like region (in the first embodiment, the direction that coincides with the longitudinal direction of the light guide plate)._kAre arranged to form
Each strip region R_k, Dot is vertical line 1_kMultiple horizontal lines 2 orthogonal to_kAre arranged to form
Here, vertical line 1_kSpacing and horizontal line 2_kThe interval between the band-shaped regions R_kDistribution density D required for_kIs set to satisfy.
[0017]
(Adjacent strip region R_k, R_{k + 1}Satisfying dot arrangement conditions between
In the first embodiment, each strip region R_kVertical line 1 formed by dot arrangement in_kThe interval between the adjacent strip regions R_{k + 1}Vertical line 1 formed by dot arrangement in_{k + 1}The interval is set differently.
In addition, two adjacent strip regions R_k, R_{k + 1}In between, one strip region R_kVertical line 1 formed by dots in_kAnd the other strip region R_{k + 1}Vertical line 1 formed by dots in_{k + 1}The dots are arranged so that and do not constitute one straight line.
[0018]
In the present invention, the portion where the bright line is more likely to occur is the strip region R._kVertical line 1_kAnd strip region R_{k + 1}Vertical line 1_{k + 1}It is preferable to increase the distance, and this can more effectively suppress the generation of bright lines. Therefore, in the reflective surface of the light guide plate, in the vicinity of the extension line of the optical axis of the light source, the band-like region R_kAdjacent vertical line 1_kA strip region R on the center line of_{k + 1}Vertical line 1_{k + 1}It is preferable to set so as to be positioned.
[0019]
Thus, in the first embodiment, the adjacent strip region R_k, R_{k + 1}Between the strips R_kVertical line 1_kInterval and strip region R_{k + 1}Vertical line 1_{k + 1}The interval between them is set differently, and the strip region R_kVertical line 1_kAnd strip region R_{k + 1}Vertical line 1_{k + 1}By arranging the dots so as not to form one straight line, the arranged dots do not form one straight line over a long distance, so that generation of bright lines can be prevented.
That is, in the first embodiment, the dots are arranged on a straight line in each strip region Rk._kIs limited to a limited area, the arranged dots do not form one straight line over a long distance, and even if the dots are arranged on the straight line in each strip-like area Rk, There are no visible bright lines.
Thus, in the first embodiment, each strip region R_kInside, dots are arranged according to a certain rule to prevent the uneven distribution of dots, and the arrangement rule is made different between adjacent strip regions to prevent the generation of bright lines.
[0020]
Here, in the first embodiment, the adjacent strip region R_k, R_{k + 1}Between the strips R_kVertical line 1_kInterval and strip region R_{k + 1}Vertical line 1_{k + 1}The interval between them is set differently, and the strip region R_kVertical line 1_kAnd strip region R_{k + 1}Vertical line R_{k + 1}However, the present invention is not limited to this, and the position of the vertical line in each belt-like region may be set so as to satisfy one of the conditions.
[0021]
That is, the adjacent strip region R_k, R_{k + 1}Between the strips R_kVertical line 1_kInterval and strip region R_{k + 1}Vertical line 1_{k + 1}If the interval between them is set to be different, the adjacent strip region R_k, R_{k + 1}Even if some dots may form one straight line across the three strip regions R_k, R_{k + 1}, R_{k + 2}There is almost no single straight line in between. Therefore, in the present invention, the adjacent strip region R_k, R_{k + 1}Between the strips R_kVertical line 1_kInterval and strip region R_{k + 1}Vertical line 1_{k + 1}The effect similar to that of the first embodiment can be obtained only by setting different intervals.
One strip region R_kInside, for example, a vertical line 1 near the center_kThe interval between and the vertical line 1 on both sides_kWhen the dots are arranged so that the interval between them is different, the strip region R_kVertical line 1_kAnd strip region R_{k + 1}Vertical line 1_{k + 1}As long as they do not form one straight line, the same effects as those of the first embodiment can be obtained.
[0022]
(Dot arrangement at the corners 52a and 52b of the reflecting surface)
Further, in the light guide plate of the first embodiment, dots are randomly arranged on the reflecting surface at corners 52a and 52b located on both sides of the end surface where the light source 10 is provided so as to have a predetermined density.
Since the corners 52a and 52b are dark portions because light is not transmitted due to the directivity of the light source, it is necessary to increase the dot density compared to other portions, and it is necessary to arrange them according to a certain rule. Therefore, in the first embodiment, dots are randomly arranged.
Here, in the corners 52a and 52b, after arranging dots according to the same rule as that of the belt-like region, random arrangement with a predetermined density may be realized by adding dots at random.
[0023]
Hereinafter, an example of the dot arrangement pattern setting method according to the first embodiment will be described.
(First step)
In this method, first, the dot size is determined in consideration of the shape of the light guide plate and the manufacturing method applied when dots are actually formed.
(Second step)
Next, the area ratio of each position on the reflecting surface (ratio of the area occupied by dots per unit area) is set so that the light emission intensity on the light emitting surface is uniform within the surface. Here, the area ratio is set according to the attenuation amount of light input from the light source, and the area ratio increases as the attenuation amount of light increases.
Then, based on the area ratio and the dot size determined in step 1, a dot density curve (C1 shown in FIG. 3) is created.
[0024]
(Third step)
Next, based on the dot density curve (C1 shown in FIG. 3) created in the second step, the border region R is set by setting a boundary every time the dot density increases by ΔDy._k(K = 1, 2, 3,..., Rn) and each strip region R_kFor example, the dot density D is an average value of the maximum dot density and the minimum dot density on the dot density curve C1 corresponding to each region._kSet to.
[0025]
(4th step)
Next, the dot density D set for each region_kAs shown in FIG._kIs further divided into lattices, and each lattice La_kOne dot is placed at the center of the. That is, each lattice La_kBy forming one dot for each, the strip region R_kDot density D_kIs realized so that each lattice La_kSet the size of.
More specifically, first, the area SLa of each lattice is obtained by the following equation (1), and the length P of one side of each lattice is determined from the square root of the obtained area (equation (2)).
Area SLa = (unit area) / (dot density D_k) ... (1)
Length of one side of lattice P = √ (area SLa) (2)
[0026]
When the dot arrangement is determined as described above, the adjacent strip region R_k, R_{k + 1}In the meantime, since the dot densities are different from each other, the length of one side of the lattice is different, so_kVertical line 1_kInterval and strip region R_{k + 1}Vertical line 1_{k + 1}The interval is set differently.
As a result, the strip region R_kVertical line 1_kAnd strip region R_{k + 1}Vertical line R_{k + 1}And dots can be arranged so as not to form one straight line, and generation of bright lines can be prevented.
In addition, when the dot arrangement is set in this way, some dots may be arranged on one straight line in the adjacent belt-like regions, but one straight line is formed over the three belt-like regions. Since it is almost impossible to do so, it is possible to prevent the generation of visible bright lines.
Needless to say, the dots arranged as described above constitute a new lattice having a lattice point at the center of the lattice dividing each band-like region.
[0027]
In the light guide plate of the surface light emitting device according to the first embodiment described above, dots are arranged by defining a band-like region over the entire reflection surface excluding the corners 52a and 52b.
However, the present invention is not limited to this, and the generation of bright lines is more effectively prevented in a portion of the reflective surface where bright lines close to the light source are particularly noticeable (for example, a portion indicated by 51 in FIG. 1). Dots may be placed as possible.
[0028]
Embodiment 2. FIG.
Hereinafter, the light guide plate of Embodiment 2 will be described.
As shown in FIG. 5, the light guide plate of the second embodiment is obtained by randomly arranging dot arrangements on the end face side where the light source 10 is provided, and is more effective than the light guide plate of the first embodiment. This prevents the generation of bright lines.
Specifically, in the light guide plate of the second embodiment, the dots on the end face side where the light source 10 is provided are the dot arrangement of the area 53 in front of the light source 10 and the corners 54a and 54b located on both sides of the area 53. Similar to the first embodiment, the dots are arranged in a random manner so as to satisfy a predetermined dot density, and in the region 57 (region away from the end face where the light source 10 is provided) excluding the region 53 and the corners 54a and 54b. It is a thing.
[0029]
Hereinafter, the dot arrangement of the region 53 and the corners 54a and 54b in Embodiment 2 according to the present invention will be described in detail.
In the light diffusing dot pattern on the light guide plate reflecting surface of the second embodiment, in the region 53, the dot density increases as the distance from the light source 10 increases corresponding to the attenuation of light input from the light source 10, and the dots are linear. It is characterized by having a distribution that is randomly arranged so as not to line up, and this suppresses the generation of bright lines on the exit surface of the light guide plate (particularly in the vicinity of the light source 10).
In the second embodiment, the dot density in the region 53 is set based on the dot density curve of FIG. 3 described in the first embodiment.
[0030]
Hereinafter, a method for creating a light diffusing dot pattern in the region 53 in the second embodiment will be described with reference to the flowchart of FIG.
In this creation method, in step S1, data relating to the light guide plate necessary for creating the light diffusion dot pattern including the shape of the light guide plate, the incident position of light (position where the light source is provided), and the shape and dimensions of the dots are obtained. input.
Next, in step S2, the number of vertical and horizontal divisions on the light guide plate reflection surface is determined based on the data (the shape of the light guide plate and the shape and dimensions of the dots) related to the light guide plate input in step S1.
[0031]
Here, in determining the vertical and horizontal division numbers, it is preferable that one side of each divided area is set to a multiple or a substantially multiple of the dot diameter. In this way, dots can be formed without gaps in each region, and gaps between dots can be eliminated between adjacent regions.
In the present invention, preferably, the number of vertical and horizontal divisions to be determined is formed so that the divided area is substantially square and in the divided area so that the dot density can be changed smoothly. The division number is determined so that the maximum number of dots that can be satisfied satisfies the following relationship.
That is, when the dots are circular, the mesh is divided so that the product of the maximum number of dots that can be arranged in each region and the diameter of the dots is 5 to 10 (mm).
When the dots are square, mesh division is performed so that the product of the maximum number of dots that can be arranged in each region and one side of the dots is 5 to 10 (mm).
[0032]
An example of the processing in step S2 is as follows when the size of the light guide plate is 66 mm in length, 18 mm in width, and the dot is a circle with a diameter of 60 μm.
First, from the relationship described above, 83 to 167 ((5 to 10) mm / 0.06 mm) are obtained as a preferable range of the maximum number of dots in the region.
Next, 9 to 13 dots are obtained as a preferable number of dots arranged on one side of a substantially square region from the preferable range of the maximum number of dots.
Using the value obtained by multiplying the preferred number of dots (9 to 13) arranged on one side in each of the vertical and horizontal directions of the area thus obtained and the dot diameter of 0.06 mm as a guideline, A preferable range is set.
For example, in the case of a light guide plate having the above dimensions, the vertical direction is divided into 100 and one side in the vertical direction is 0.660 mm, and the horizontal direction is divided into 30 and one side in the horizontal direction is 0.600 mm. To divide.
By dividing in this way, if 11 dots are arranged in the vertical direction and 10 dots are arranged in the horizontal direction in each region, 110 dots can be arranged in each dot without any gap. Further, when divided in this way, dots can be arranged so that no gap is formed between the dots between adjacent regions.
[0033]
In step S3, the required number of dots formed in each region divided in step S2 is determined in accordance with the amount of light attenuation in the light guide plate.
Specifically, a density function corresponding to the amount of light attenuation in the light guide plate is created, and the required number of dots to be formed in each region is determined based on the density function.
This density function represents the density distribution of dots with respect to the distance and direction from the light source on the reflecting surface of the light guide plate (that is, the position on the reflecting surface), and becomes smaller near the light source where the attenuation of light is small. It becomes large at a place away from a light source with large attenuation. Further, the density function tends to increase in the area where the angle with the optical axis of the light source is large, and decreases in the area where the angle with the optical axis of the light source is small.
[0034]
The density function in the case where there are a plurality of light sources can be created based on the total of all the density functions created corresponding to the individual light sources.
FIG. 7 shows an example of a list of the required number of dots to be formed in each region determined in step S3 (an example in which the vertical and horizontal are divided into five). In the example of FIG. 7, the light source is provided in front of the first column and the third column.
[0035]
In step S4, a mesh corresponding to the number of divisions determined in step S2 is cut on the reflection surface of the light guide plate on a computer display, for example, and a cell corresponding to each divided region is created.
FIG. 8 shows an example of a mesh divided into 25 squares M11 to M55 of 5 × 5 corresponding to FIG.
In step S5, as shown in FIG. 9A, the maximum number of circles having a diameter R corresponding to the dot shape (simply referred to as dots 21) that can be arranged in each cell is drawn (closest packed arrangement). .
Next, in step S6, the number of dots necessary for each square (determined in step S3 for each square is determined by randomly deleting the extra dots from the dots 21 that are closest packed in step S5 in each square. Number) of dots 21 are left.
Thereby, a circle corresponding to a required number of dots drawn at random is formed on each square.
[0036]
In this way, a light diffusing dot pattern having a distribution that is randomly arranged so that the density increases as the distance from the light source increases, and the dots do not line up in a straight line, corresponding to the attenuation of light input from the light source. Can be created.
[0037]
In the second embodiment, in steps S5 and S6, after the maximum number of circles are drawn on all the squares, the process proceeds to step S6, and the extra circles are randomly randomized from the closest packed circle for each square. In step S5, a maximum number of circles are drawn on one square, and in step S6, extra circles are randomly deleted from the square on which the maximum number of circles are drawn. You may make it repeat step S5 and step S6 for every square.
[0038]
Modification of Embodiment 2
In the light diffusion pattern creation method of the second embodiment described above, circles corresponding to dots are aligned in each square in step S5, and extra circles are randomly extracted from the circles arranged in each square in step S6. However, the present invention is not limited to this, and may be as follows instead of steps S5 and S6.
That is, as shown in FIG. 10A, the position 22 where dots are arranged is set so that the maximum number of dots can be packed without overlapping each other in each mesh-divided cell,
As shown in FIG. 10B, dots 21 having a diameter R are randomly arranged at positions such that the number of dots becomes the required number determined in step S3 in each square where the positions where the dots are arranged are set. .
Even in this case, the light diffusing dots have a distribution that is randomly arranged so that the density increases as the distance from the light source increases in accordance with the attenuation amount of light input from the light source, and the dots do not line up in a straight line. A pattern can be created.
[0039]
According to the method for creating a light diffusing dot pattern according to the second embodiment and the modification of the second embodiment, a light diffusing dot pattern capable of suppressing the generation of bright lines on the exit surface can be created easily and easily in a short time. it can.
In addition, according to the light diffusing dot pattern creation method of the second embodiment and the modification of the second embodiment, the light diffusing dot pattern can be easily corrected.
[0040]
In Embodiment 2 described above, the dot shape has been described as a circle, but the present invention is not limited to this, and may be another shape such as a square.
Even if it does as mentioned above, the effect similar to Embodiment 2 is acquired.
In this case, for example, in the light diffusing dot pattern created according to steps S1 to S6, the light consisting of the square dots is formed so that the centers of the square dots actually forming the centers of the circular dots coincide with each other. A diffusion dot pattern may be formed.
[0041]
In the second embodiment described above, the method of creating a light diffusion dot pattern in which the dot shape is circular and the dot 1 is provided without a gap between the dots has been described. However, the present invention is not limited to this. For example, the present invention can also be applied to the case where dots having a diameter r (r <R) formed at regular intervals are actually formed.
In this case as well, for example, in the light diffusing dot pattern created according to steps S1 to S6, the center of the circular dot 1 having a diameter R formed without a gap and the actually formed diameter r is smaller than R. A light diffusing dot pattern composed of dots having a certain gap can be formed so that the centers of the dots coincide with each other.
In this case, the interval between adjacent dots formed closest to each other is (R−r) within the same cell and between adjacent cells.
[0042]
(Setting of the region 53 to which the random arrangement is applied)
In the second embodiment, the region 53 where dots are randomly arranged is set as follows, for example.
As described above, the second embodiment applies a random dot arrangement to a place where bright lines are particularly likely to occur.
Therefore, in consideration of the location where the bright line is likely to be generated on the light guide plate, the position where the dots are randomly arranged can be defined by a circle centered on the light emitting point of the light source 10.
Specifically, as shown in FIG. 11, for example, a semicircle C53 having a diameter equal to the width of the light guide plate is drawn around the center of one end surface where the light source 10 is provided, and corners 54a, A portion excluding 54b is defined as a region 53 in which dots are randomly arranged. When the region 53 is defined in this range and the arrangement described in the first embodiment is applied to the other portions except the region 53 and the corners 54a and 54b, extremely high luminance uniformity is obtained on the light emitting surface of the light guide plate. can get.
Here, the reason why the corners 54a and 54b are excluded from the semicircle C53 is that the corners 54a and 54b are portions where the bright lines are hardly generated due to the directivity of the light source 10. Since the light source 10 has directivity in the corners 54a and 54b, the corners 54a and 54b are darker than the other parts (the amount of light attenuation is large). It is preferable to increase the number.
In the corners 54a and 54b, as long as the preferable dot density is satisfied, dots may be randomly arranged or regularly arranged.
[0043]
Further, when the region 53 in which dots are randomly arranged is defined as shown in FIG. 11, the portion where the bright line is likely to be generated changes depending on, for example, the directivity characteristics of the light source and the semicircle C53 according to the characteristics of the light source. The diameter can be made smaller than the width of the light guide plate.
[0044]
In the second embodiment, the area 53 may be defined as shown in FIG. 12 instead of the sector area 53 shown in FIG.
That is, in FIG. 12, the corners 54a and 54b are removed from the region defined as the region on the light source side from the region boundary line T53 parallel to the end surface where the light source is provided, which is a tangent to the semicircle C53 described in FIG. A portion may be defined as the region 53.
In this case, the region 53 may be defined by a region boundary T53a that is further separated from the light source by about 0 to 5 mm.
[0045]
In the portion farther from the light source than the region 53 defined as described above (the portion denoted by reference numeral 58 in FIG. 13), as shown in FIG. The light is mixed and the generation of bright lines is suppressed.
[0046]
As described above, in the present invention, it is preferable that the dots shown in the second embodiment are randomly arranged particularly in the portion where the bright line is significantly generated due to the influence of the directivity characteristics of the light source. Generation of bright lines can be prevented.
[0047]
Modified example.
(Dot shape)
In the present invention, the dot may be a dot formed of a concave portion or a dot formed of a convex portion, and those having various shapes described below can be applied.
Hereinafter, preferred dot shapes that can be used in the present invention will be described with reference to FIGS. Here, in FIGS. 14 to 19, (a) is a cross-sectional view and (b) is a plan view, respectively.
The present invention is not limited to the dot shape shown in FIGS. 14 to 19 and can be applied to other shapes.
[0048]
Hereinafter, the shape shown in each figure will be briefly described.
FIG. 14 shows dots formed by relatively simple recesses that are recessed from the reflection reference surface Rf, and the dots of this shape are easy to manufacture.
FIG. 15 is a dot in which a peak raised from the reflection reference surface Rf is formed in a ring shape, and FIG. 16 is a dot formed around the concave portion of FIG. The dots have a higher light scattering effect than the dots formed by the simple recesses in FIG.
[0049]
FIG. 17 shows dots formed by relatively simple convex portions raised from the reflection reference surface Rf, and the dots of this shape are easy to manufacture.
Further, FIG. 18 is a dot whose central portion is raised in a dot that is recessed from the reflection reference surface Rf, and FIG. 18 is a dot that is recessed in the periphery of the dot that is a convex portion in FIG. The dots in FIGS. 18 and 19 have a higher light scattering effect than the dots having simple convex portions in FIG.
[0050]
For example, when one dot shown in FIG. 15, FIG. 16, FIG. 18, and FIG. 19 has a convex portion and a concave portion and has a high light scattering ability, a pointed pin is pressed against a resin plate to form the concave portion. By utilizing the fact that the periphery of the concave portion swells, it can be manufactured relatively easily, and high reproducibility can be secured by managing the pressing conditions. In addition, this method can be applied to a mold having a plurality of pins, and mass production is also possible.
[0051]
In the present invention, by utilizing the fact that the light scattering ability of the dots varies depending on the shape of the dots described above, each portion of the light emitting surface including the dot density and arrangement described in the first and second embodiments and the shape of each dot is used. The brightness at can be adjusted. In this way, it is possible to adjust the luminance of the light emitting surface more delicately, which cannot be adjusted only with the dot density and the arrangement.
In particular, the shape of the dots in the portions 54a and 54b where the amount of light tends to be small and the portions where the luminance is not sufficiently high only by the dot density and arrangement such as the portions where the amount of light away from the light source is small and the portion tends to be dark. The light emission luminance can be increased by effectively diffusing light.
[0052]
Furthermore, in FIGS. 14 to 19, an example is shown in which dots having a circular planar shape are used, but the present invention is not limited to this, and may be other shapes such as a square or a polygon.
In Embodiments 1 and 2, the dot density is preferably set to 10 to 78.5% when circular dots are used, and the dot density is set to 10 to 100% when square dots are used. It is preferable to set.
Furthermore, according to the present invention, the shape of the dots may be different for each region depending on the amount of light scattering as required, whereby the light emission luminance on the light emitting surface can be made more uniform.
[0053]
【The invention's effect】
As described above in detail, the light guide plate of the surface light-emitting device according to the present invention is such that the dots form a band-shaped region defined as a region having a certain distribution density on the reflective surface and adjacent to it. Since the vertical lines are arranged so as not to form one straight line over a long distance between the belt-like regions, generation of bright lines can be prevented.
In the present invention, it is also possible to randomly arrange dots so that the required dot density is satisfied in a portion where the generation of bright lines is remarkable, thereby preventing the generation of bright lines more effectively.
Therefore, according to the present invention, it is possible to provide a light guide plate that can emit light uniformly from the light emitting surface and can suppress generation of bright lines.
[Brief description of the drawings]
FIG. 1 is a plan view showing a distribution of dots formed on a reflective surface of a light guide plate according to a first embodiment of the present invention.
2 is an enlarged plan view showing a part 51 of FIG. 1. FIG.
3 is a graph showing a dot density curve of dots formed on the reflection surface of the light guide plate according to Embodiment 1. FIG.
FIG. 4 is a plan view when a grid is formed in each band-like region in the dot pattern setting method according to the first embodiment.
FIG. 5 is a plan view showing a distribution of dots formed on a reflection surface of a light guide plate according to a second embodiment of the present invention.
FIG. 6 is a flowchart of a method for creating a light diffusion pattern in a region 53 according to the second embodiment of the present invention.
7 is a diagram showing an example of a list of required numbers of dots formed in each region determined in step S3 in the light diffusion pattern creation method of Embodiment 2. FIG.
FIG. 8 is a plan view showing an example in which the reflection surface of the waveguide is cut into a mesh in step S4 in the light diffusion pattern creation method of the second embodiment.
FIG. 9A is a diagram illustrating a state in which a circle corresponding to the maximum number of dot shapes that can be arranged in each cell is drawn in step S5 in the light diffusion pattern creation method according to the second embodiment; ) Is a diagram showing a state in which a necessary number of circles are left in each square by randomly deleting extra circles from the closest packed circle in step S5 in step S6.
FIG. 10A is a diagram illustrating a light diffusing pattern creation method according to a modification of the present invention in which dots are arranged so that the maximum number of dots can be packed in each mesh-divided cell without overlapping each other. FIG. 8B is a diagram showing a state in which positions to be set are set, and FIG. 8B is a diagram in which dots are randomly placed at positions such that the number of dots becomes the required number determined in step S3 in each square in which the positions where the dots are arranged are set. It is a figure which shows the state after arrange | positioning.
FIG. 11 is a plan view showing a range of a region 53 in the second embodiment.
12 is a plan view showing a region 53 set in a different range from that in FIG. 11 in Embodiment 2. FIG.
FIG. 13 is a plan view illustrating the progress of light in the second embodiment.
FIGS. 14A and 14B are a cross-sectional view (a) and a plan view (b) showing a dot shape (Example 1) applicable to the light guide plate according to the present invention. FIGS.
FIGS. 15A and 15B are a sectional view and a plan view showing a dot shape (example 2) applicable to the light guide plate according to the present invention. FIGS.
FIGS. 16A and 16B are a sectional view and a plan view showing a dot shape (example 3) applicable to the light guide plate according to the present invention. FIGS.
FIGS. 17A and 17B are a cross-sectional view (a) and a plan view (b) showing a dot shape (example 4) applicable to the light guide plate according to the present invention. FIGS.
18A and 18B are a cross-sectional view and a plan view showing a dot shape (Example 5) applicable to the light guide plate according to the present invention.
FIGS. 19A and 19B are a cross-sectional view (a) and a plan view (b) showing dot shapes (Example 6) applicable to the light guide plate according to the present invention. FIGS.
FIG. 20 is a plan view of a general surface emitting device.
FIG. 21 is a plan view showing an example of a dot pattern formed on a reflection surface of a conventional light guide plate.
[Explanation of symbols]
1_k... vertical line,
2_k… Horizontal line,
10 ... light source,
21 ... dot,
53 ... A region where dots are randomly arranged,
52a, 52b, 54a, 54b ... corners,
R_k... banded area.
M11 to M55 Mass formed by cutting a mesh.

Claims (7)

A plurality of dots are formed on the reflection surface so that light input from a light source provided on one end surface or two opposite end surfaces is uniformly emitted from the emission surface. In the light guide plate of the surface emitting device made,
The dots are arranged so that a band-like region defined as a region having a certain distribution density is formed, and the distribution density of the band- like region is separated from the light source according to the attenuation amount of light input from the light source. Therefore, it is set to increase by a certain amount sequentially,
In each of the belt-like regions, a plurality of vertical lines in the direction toward the adjacent belt-like region is formed at substantially equal intervals by arranging the dots,
The light guide plate of a surface light-emitting device, wherein intervals between vertical lines formed by the dots in each of the band-like regions are set to be different from each other between adjacent band-like regions.   In each band-like region, the dots are arranged so as to form a plurality of horizontal lines orthogonal to the vertical line, and the interval between the vertical lines and the interval between the horizontal lines are the distribution density of dots in the band-like region. The light guide plate of the surface light-emitting device according to claim 1, which is set based on the above.   3. The dot according to claim 1, wherein the dots are randomly arranged so as to have a density set in accordance with the amount of attenuation of light on a part of the reflecting surface located on both sides of the end face provided with the light source. A light guide plate of a surface light emitting device.   4. The device according to claim 1, wherein the dots are randomly arranged in a part of the reflecting surface located in the vicinity of the light source so that the dots have a density set according to the amount of light attenuation. A light guide plate of the surface light-emitting device according to 1.   The light guide plate of the surface light-emitting device according to claim 1, wherein each of the dots has a concave portion and a convex portion.   The light guide plate of a surface light-emitting device according to claim 5, wherein each of the dots includes a convex portion and a concave portion formed around the convex portion.   6. The light guide plate for a surface light emitting device according to claim 5, wherein each of the dots comprises a concave portion and a convex portion formed around the concave portion.

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