CN101351671A - Planar light emitting device, optical element and liquid crystal display device - Google Patents
Planar light emitting device, optical element and liquid crystal display device Download PDFInfo
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- CN101351671A CN101351671A CNA2007800010196A CN200780001019A CN101351671A CN 101351671 A CN101351671 A CN 101351671A CN A2007800010196 A CNA2007800010196 A CN A2007800010196A CN 200780001019 A CN200780001019 A CN 200780001019A CN 101351671 A CN101351671 A CN 101351671A
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Abstract
The invention provides a planar light emitting device, an optical element and a liquid crystal display device. A maximum tangent angle (a) satisfying the relationship of x>L/2-D/2 is included when a moving distance (x) from a light source in a direction orthogonally intersecting with an optical axis of a divided image of a light source is calculated, with the formulas of (1) n0sin(a)=nsin(a-theta 2), (2) n0 sin theta 1=n sin theta 2, (3) x=W tan theta 1+dtan theta 2, where (L) is a distance between the centers of light sources (12, 12), (n) is a refractive index of an optical element (15), (d) is a thickness of the optical element, (W) is a distance from the center of the light source to the optical element, (n0) is a refractive index of air, (theta 1) is an incidence angle to the optical element, (theta 2) is a refractive angle of the optical element, and (a) is the maximum tangent angle formed by a tangent making contact with the diameter (D) of the light source and an outer surface of a luminance distribution forming layer (18) of the optical element and a surface orthogonally intersecting with the optical axis. Thus, front luminance distribution is made uniform.
Description
Technical field
The present invention relates to surface illuminating device, optical element and liquid crystal indicator.Relate in particular to the split image of overlapping light source between light source and suppress the technical field of brightness disproportionation.
Background technology
At present, the display unit as personal computer of word processor or laptop etc. can adopt the liquid crystal indicator that comprises (surface illuminating device) backlight.The surface illuminating device of using as such liquid crystal indicator, in order to respond the requirement of lightness and slimming, the main flow that becomes backlight that end face is illuminated, the such linear light source of side configuration fluorescent tube at transparent plate body (LGP) backlight of this end face illuminated (edge-light-type) disposes display panels on LGP.
But, along with the maximization of the liquid crystal indicator of TV purposes in recent years etc., luminance shortage mostly in illuminated backlight of end face, thus adopt the backlight of the straight-down negative that under display panels, disposes linear light source more.
Figure 32 is the stereogram that the summary of the back lighting device 1 of expression straight-down negative of the prior art constitutes.Back lighting device 1 comprises light source (linear light source) 2,2... and reflecting plate 3 and diffuser plates 4 such as fluorescent tube.
As light source (linear light source) 2,2..., for example can adopt cold cathode fluorescent tube (CCFL:Cold Cathode Fluorescent Lamp) etc., and form to the direction of regulation extend cylindric.
Reflecting plate 3 disposes in order to utilize by the light of reflections such as diffuser plate 4 or from the light of the no show diffuser plate 4 of light source 2,2... again.
In the back lighting device 1, clipping on the both sides respect to one another of light source 2,2..., disposing reflecting plate 3 and diffuser plate 4 respectively.
In such back lighting device 1, can be from the light that light source 2,2... penetrate from diffuser plate 4 bright dippings, but when the distance of light source 2,2... and diffuser plate 4 shortens, when perhaps the distance between light source 2, the 2... increases, as shown in figure 33, the brightness of the illumination beam of position back lighting device 1 is increased directly over light source 2,2..., and the brightness of the illumination beam of the position back lighting device 1 between light source 2,2... reduces, thereby cause the homogeneity of front luminance distribution to reduce, produce luminance deviation.
In order to suppress such luminance deviation, (for example disclose following technology, with reference to Japanese kokai publication hei 5-333333 communique, Japanese kokai publication hei 6-250178 communique, Japanese kokai publication hei 10-283818 communique, TOHKEMY 2004-6256 communique): as shown in figure 34, configuration prismatic lens or bi-convex lens sheet optical sheets (optical element) 5 such as (lenticular lens sheet) perhaps dispose optical sheets 5 such as prismatic lens or bi-convex lens sheet and replace diffuser plate 4 between light source 2,2... and diffuser plate 4.In addition, Figure 34 shows the example that configuration optical element (prismatic lens) 5 replaces the diffuser plate 4 of Figure 33.
Optical element (prismatic lens) 5 generally is the optical element that improves sheet (sheet forimproving luminance) as brightness, this optical element (prismatic lens) 5 have in the front or the back side with that be provided with, for example triangle continuously a plurality of wire projections (prism) uniformly-spaced.These wire projections form layer 5a as Luminance Distribution and play a role, and this Luminance Distribution forms the luminance deviation that layer 5a is used to suppress the optical axis direction of the light that penetrates from light source 2,2....
But, in above-mentioned existing surface illuminating device 1, if existence light source 2,2 ... and the distance between the optical element 5 changes the then easy problem that very big brightness disproportionation takes place.The variation of distance for example can be owing to following reason produces: the machining accuracy of each several part or assembly precision or because environmental changes such as variations in temperature cause the distortion of optical element.
For example, as shown in figure 35, when light source 2,2 ... the center and the distance of optical element 5 when being H, can obtain respectively for each light source 2,2 ... split image 2A, 2A ... the surface illuminating device of front luminance distribution of homogeneous in, when the designed distance H of optical element 5 has changed Δ H, cause becoming the state that is easy to take place brightness disproportionation as shown in figure 36.
In surface illuminating device 1, under the state that keeps the distance H in the design, the split image 2A of light source 2 and the split image 2A of adjacent light source 2 are not overlapping, and when changing owing to distance H, front luminance distribution sharply changes, thereby causes taking place this brightness disproportionation.That is, if distance H changes delta H, then cause each light source 2,2 ... split image 2A, 2A ... overlapping, thereby become front luminance distribution is produced the state sharply change and be easy to take place brightness disproportionation.
Therefore, in order to obtain the front luminance distribution of homogeneous as shown in figure 35, designed light source 2,2 ... and the distance between the optical element 5, still, this design freedom is very narrow.
In addition, along with the giant-screenization of in recent years liquid crystal indicator, surface illuminating device (back lighting device) also maximizes.Therefore, optical elements such as prismatic lens that disposes to realize the front luminance distribution homogeneous to turn to purpose or bi-convex lens sheet also maximize.
But, if these optical elements maximize, then take place easily because bending that deadweight causes or warpage etc., be difficult on whole of optical element stable and keep distance between optical element and the light source regularly.Therefore, will produce deviation on the distance between optical element and the light source, as shown in figure 36, can cause hindering the homogenization of front luminance distribution, and be easy to take place brightness disproportionation.
Summary of the invention
In order to address the above problem, the invention provides surface illuminating device, optical element and liquid crystal indicator, it can guarantee the homogenization of front luminance distribution, even and the distance between light source and the optical element change, also can suppress the generation of brightness disproportionation.
In order to solve above-mentioned problem, surface illuminating device, optical element and liquid crystal indicator comprise maximum tangential angle a, wherein, for maximum tangential angle a, when each distance between centers with the light source of adjacent position is made as L, the refractive index of optical element is made as n, the thickness of optical element is made as d, distance on the optical axis direction till will be from the light source center to the optical element is made as W, and the air refraction of air layer is made as n
0, the light that will penetrate and inject optical element from light source is made as θ with respect to the angle of injecting of optical axis direction
1, the refraction angle of light in optical element of injecting optical element is made as θ
2The diameter of light source is made as D, will with the cross sectional shape of the length direction quadrature of the cambial structure of Luminance Distribution portion in, the tangent line that contacts with the cambial outer surface of Luminance Distribution and be made as tangential angle φ with the formed angle of the face of light shaft positive cross, tangential angle maximum among the tangential angle φ is made as maximum tangential angle a, and by (1) n
0Sin (a)=nsin (a-θ
2), (2) n
0Sin θ
1=nsin θ
2, (3) x=Wtan θ
1+ dtan θ
2, the split image of calculating light source with the light shaft positive cross direction under the situation apart from the displacement x of light source, maximum tangential angle a satisfies x＞L/2-D/2.
Therefore, in surface illuminating device, optical element and liquid crystal indicator, the split image of at least a portion of each light source of adjacent position is overlapping.
Surface illuminating device of the present invention comprises: a plurality of light sources, each light source form to prescribed direction extend cylindric, under the state that extends to same direction, be configured at grade; Optical element has light transmission, and is formed with Luminance Distribution and forms layer, and Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of light sources; And reflecting surface, be positioned at the opposite side of optical element in the mode that clips a plurality of light sources, air layer is between reflecting surface and optical element, and, reflecting surface is used to reflect the light that penetrates from light source, in surface illuminating device, the Luminance Distribution of optical element forms that layer is extended by the length direction to light source and constitutes to the outstanding a plurality of structure portion of optical axis direction, in surface illuminating device, comprise: optical element comprises maximum tangential angle a, wherein, for maximum tangential angle a, when each distance between centers with the light source of adjacent position is made as L, the refractive index of optical element is made as n, the thickness of optical element is made as d, distance on the optical axis direction till will be from the light source center to the optical element is made as W, and the air refraction of air layer is made as n
0, the light that will penetrate and inject optical element from light source is made as θ with respect to the angle of injecting of optical axis direction
1, the refraction angle of light in optical element of injecting optical element is made as θ
2 The diameter of light source is made as D; Will with the cross sectional shape of the length direction quadrature of the cambial structure of Luminance Distribution section in; The tangent line that contacts with the cambial outer surface of Luminance Distribution and be made as tangential angle φ with the formed angle of the face of light shaft positive cross; Tangential angle maximum among the tangential angle φ is made as maximum tangential angle a; And by following conditional (1) to conditional (3); The split image of calculating light source with the light shaft positive cross direction in the situation apart from the displacement x of light source; Maximum tangential angle a satisfies x＞L/2-D/2
n
0sin(a)＝nsin(a-θ
2)......(1)
n
0sinθ
1＝nsinθ
2 ......(2)
x＝Wtanθ
1+dtanθ
2 ......(3)。
Optical element of the present invention is formed with Luminance Distribution and forms layer, Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of light sources, each light source forms to the cylindric of prescribed direction extension and is being configured at grade under the state that extends to same direction, Luminance Distribution forms that layer is extended by the length direction to light source and constitutes to the outstanding a plurality of structure portion of optical axis direction, optical element comprises: maximum tangential angle a, when each distance between centers with the light source of adjacent position is made as L, the refractive index of optical element is made as n, the thickness of optical element is made as d, distance on the optical axis direction till will be from the light source center to the optical element is made as W, and the air refraction of air layer is made as n
0, the light that will penetrate and inject optical element from light source is made as θ with respect to the angle of injecting of optical axis direction
1, the refraction angle of light in optical element of injecting optical element is made as θ
2 The diameter of light source is made as D; Will with the cross sectional shape of the length direction quadrature of the cambial structure of Luminance Distribution section in; The tangent line that contacts with the cambial outer surface of Luminance Distribution and be made as tangential angle φ with the formed angle of the face of light shaft positive cross; Tangential angle maximum among the tangential angle φ is made as maximum tangential angle a; And by following conditional (1) to conditional (3); The split image of calculating light source with the light shaft positive cross direction in the situation apart from the displacement x of light source; Maximum tangential angle a satisfies x＞L/2-D/2
n
0sin(a)＝nsin(a-θ
2) ......(1)
n
0sinθ
1＝nsinθ
2 ......(2)
x＝Wtanθ
1+dtanθ
2 ......(3)。
Liquid crystal indicator of the present invention comprises: a plurality of light sources, each light source form to prescribed direction extend cylindric, under the state that extends to same direction, be configured at grade; Optical element, has light transmission, and be formed with Luminance Distribution and form layer, Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of light sources, and Luminance Distribution forms that layer is extended by the length direction to light source and constitutes to the outstanding a plurality of structure portion of optical axis direction; Reflecting surface is positioned at the opposite side of optical element in the mode that clips a plurality of light sources, and air layer is between reflecting surface and optical element, and reflecting surface is used to reflect the light that penetrates from light source; And liquid crystal panel, be used for display image, and irradiation there is the light that penetrates from a plurality of light sources, in liquid crystal indicator, comprise: optical element comprises maximum tangential angle a, wherein, for maximum tangential angle a, when each distance between centers with the light source of adjacent position is made as L, the refractive index of optical element is made as n, the thickness of optical element is made as d, distance on the optical axis direction till will be from the light source center to the optical element is made as W, and the air refraction of air layer is made as n
0, the light that will penetrate and inject optical element from light source is made as θ with respect to the angle of injecting of optical axis direction
1, the refraction angle of light in optical element of injecting optical element is made as θ
2 The diameter of light source is made as D; Will with the cross sectional shape of the length direction quadrature of the cambial structure of Luminance Distribution section in; The tangent line that contacts with the cambial outer surface of Luminance Distribution and be made as tangential angle φ with the formed angle of the face of light shaft positive cross; Tangential angle maximum among the tangential angle φ is made as maximum tangential angle a; And by following conditional (1) to conditional (3); The split image of calculating light source with the light shaft positive cross direction in the situation apart from the displacement x of light source; Maximum tangential angle a satisfies x＞L/2-D/2
n
0sin(a)＝nsin(a-θ
2) ......(1)
n
0sinθ
1＝nsinθ
2 ......(2)
x＝Wtanθ
1+dtanθ
2 ......(3)。
Therefore, in surface illuminating device of the present invention, optical element and the liquid crystal indicator, because the split image of at least a portion of each light source of adjacent position is overlapping, thus can guarantee the homogeneity of front luminance distribution, and can suppress brightness disproportionation.
Description of drawings
Fig. 1 is the approximate three-dimensional map of expression liquid crystal indicator, and in addition, Fig. 2 to Figure 31 is the figure that expression is used to implement the preferred embodiment of surface illuminating device of the present invention, optical element and liquid crystal indicator;
Fig. 2 is the concept map of expression from the path of the light of light source ejaculation and the position relation of each several part etc.;
Fig. 3 is the concept map of the tangential angle (tangentialangle) in the cambial structure of the expression Luminance Distribution portion;
Fig. 4 is the front luminance distribution under the state of light is penetrated in expression from light source a curve map;
Fig. 5 is the figure that represents the example of front luminance distribution with Fig. 6 and Fig. 7 together, and to be the expression summit be the concept map of the example of the general triangular shape of radian slightly to Fig. 5;
Fig. 6 is illustrated in the concept map that rake has the example of end difference (shoulder);
Fig. 7 is the concept map that the inclination of expression rake is the example of phasic Chang;
Fig. 8 is the distance between expression light source and the optical element when changing, the curve map of the front luminance distribution before the light transmission diffuser plate;
Fig. 9 is under split image (split image) the lap situation seldom that is illustrated in light source, during variable in distance between light source and the optical element, and the curve map of the front luminance distribution before the light transmission diffuser plate;
Figure 10 be the expression light source split image with the direction of light shaft positive cross on apart from the concept map of the object lesson of the displacement of light source;
Figure 11 is the curve map that concerns between the displacement of split image of the expression cambial tangential angle of Luminance Distribution and light source;
Figure 12 is the curve map of the front luminance distribution of split image when moving to adjacent light source of expression light source;
Figure 13 is the curve map that concerns between the displacement of split image of the expression cambial maximum tangential angle of Luminance Distribution and light source;
Figure 14 be illustrated in distance between light source and the optical element be in the design apart from the time, the curve map of the front luminance distribution under the state of the light transmission diffuser plate that penetrates from light source;
Figure 15 is under the overlapping situation seldom of the split image of light source, when the distance between light source and the optical element be in the design apart from the time, the curve map of the front luminance distribution under the state of the light transmission diffuser plate that penetrates from light source;
Figure 16 shows about the low sampling of the incidence of brightness disproportionation, the curve map of expression tangential angle and its ratio;
Figure 17 shows about the high sampling of the incidence of brightness disproportionation, the curve map of expression tangential angle and its ratio;
The curve map of the front luminance distribution under the state of Figure 18 light transmission optical element that to be expression penetrate from a plurality of light sources;
Figure 19 is the concept map of an example of the cambial structure of expression Luminance Distribution portion;
Figure 20 forms layer about Luminance Distribution shown in Figure 19, the curve map of expression tangential angle and its ratio;
Figure 21 is the example about Figure 19 and Figure 20, the curve map of the front luminance distribution under the state of the light transmission optical element that expression is penetrated from a plurality of light sources;
The concept map of Figure 22 optical element package body that to be expression form by package member packing optical element, diffuser plate and optical element body;
Figure 23 is that expression engages optical element and diffuser plate and the concept map of the optical element package body that forms;
Figure 24 is the schematic diagram with cambial example of Luminance Distribution of polygonal shape;
Figure 25 is the schematic diagram of the cambial example of Luminance Distribution with structure portion of two polygonal shapes;
Figure 26 is the schematic diagram of the cambial example of other Luminance Distribution with structure portion of two polygonal shapes;
Figure 27 is the schematic diagram with metal pattern of the optical element of structure portion of two polygonal shapes and this optical element that is shaped;
Figure 28 is the schematic diagram of the cambial example of Luminance Distribution with structure portion of three polygonal shapes;
Figure 29 is the schematic diagram of the cambial example of other Luminance Distribution with structure portion of three polygonal shapes;
Figure 30 is the schematic diagram of the analog result of the front luminance distribution when lighting light source that has in the cambial optical element of Luminance Distribution shown in Figure 26;
Figure 31 is the curve map of the analog result of the front luminance distribution of expression when lighting all light sources that have in the cambial optical element of Luminance Distribution shown in Figure 26;
Figure 32 is the approximate three-dimensional map of expression surface illuminating device of the prior art;
Figure 33 is illustrated in the surface illuminating device of prior art, the concept map of an example of the front luminance distribution the when distance of light source and diffuser plate shortens;
Figure 34 is the concept map of an example of the front luminance distribution in the expression surface illuminating device of the prior art;
Figure 35 is illustrated in the surface illuminating device of prior art, with light source and optical element be configured to design apart from the time the concept map of an example of front luminance distribution; And
Figure 36 is the concept map that is used for illustrating the problem points of surface illuminating device of the prior art.
The specific embodiment
Below, with reference to accompanying drawing, the preferred embodiment that is used to implement surface illuminating device of the present invention, optical element and liquid crystal indicator is described.
With direct-type backlight (backlight) device (with reference to Fig. 1) of surface illuminating device 10 as liquid crystal indicator 50 usefulness.
As light source 12,12..., for example can adopt fluorescent tubes such as cold cathode fluorescent tube or thermic cathode fluorimetric pipe.Light source 12,12... form cylindric, and it is configured on the reflecting plate 13 under the state that extends along Y direction as shown in Figure 1. Light source 12,12... are separated on directions X shown in Figure 1 with parastate between reflecting plate 13 and optical element 15, and by the configuration of equal intervals ground.
Like this, in surface illuminating device 10, a plurality of light sources 12,12... equally spaced configuration on reflecting surface 13a, and can under configuration status, guarantee homogeneity, therefore, when the light that penetrates from light source 12,12... arrives display panels described later, be difficult to produce the local luminance inequality of the configuration status that exists with ... light source 12,12....
The face of reflecting plate 13 with respect to light source 12,12... side formed as reflecting surface 13a.The part of the light that penetrates from light source 12,12... by reflecting surface 13a to optical element 15 reflections.As reflecting plate 13, get final product so long as have catoptrical character, can adopt for example various materials of aluminum, PET (polyethylene terephthalate) system, Merlon system etc.
As diffuser plate 14, can adopt for example diffuser plate of polystyrene, cyclic olefin polymer, acrylic, Merlon system, diffusion sheet is used for the diffusion of fill-in light, as diffusion sheet, can adopt for example diffusion sheet of coating particle filled composite on the PET base material.In addition, though as long as a kind of in diffuser plate 14 and the diffusion sheet arranged, also can stacked diffuser plate 14 and diffusion sheet and being used.
Exiting surface side at diffuser plate 14 disposes not shown display panels.
Luminance Distribution forms the function of the luminance deviation on the frontal (Z direction) that layer 18 has the light that inhibition penetrates from light source 12.Luminance Distribution forms layer 18 and is made of a plurality of structure 18a of portion, the 18a... that with Y direction shown in Figure 1 are the crest line direction, and the 18a of this structure portion, 18a... arrange continuously with prescribed distance on directions X.The 18a of structure portion is outstanding to the optical axis direction of Z direction shown in Figure 1, the light that promptly penetrates from light source 12, and outer surface forms curve form or polygonal shape.When the 18a of structure portion forms curve form, for example be aspherical shape.
It doesn't matter for the arrangement pitches of the arrangement pitches of the 18a of structure portion, 18a... and light source 12,12..., and the 18a of structure portion, 18a... arrange with small spacing.
In addition, Luminance Distribution form layer 18 can by with base material 17 integrally formed formation, also can be that transfer printing is formed by ultraviolet hardening resin on base material 17 Luminance Distribution forms layer 18 and forms, perhaps also can Luminance Distribution be formed layer 18 and be engaged in base material 17 and constitute by press molding.
As in the surface illuminating device 10 of above-mentioned formation, the space between reflecting plate 13 and the optical element 15 is formed as air layer 19.
In surface illuminating device 10, when penetrating the light time from light source 12,12..., emitted light sees through optical element 15, diffuser plate 14 and optical element body 16 successively and shines on the display panels.At this moment the part of the light of She Chuing be reflected plate 13 reflecting surface 13a reflection and towards optical element 15.
The light of injecting optical element 15 is reflected by the face of injecting of this optical element 15, and then also is refracted when optical element 15 penetrates, and towards diffuser plate 14.The light of injecting diffuser plate 14 is spread and bright dipping (extract), arrives display panels through optical element body 16.
Fig. 2 shows from the path of the light of light source 12,12... ejaculation and the position relation of each several part etc.
In Fig. 2, each distance in the heart that will be arranged in the light source 12,12 of adjacent position is made as L, the refractive index of optical element 15 is made as n, the thickness of optical element 15 is made as d, to be made as W to the distance on the optical axis P direction of optical element 15 from the center of light source 12, the refractive index of the air of air layer 19 will be made as n
0, the light that will penetrate and inject optical element 15 from light source 12 is made as θ with respect to the angle of injecting of optical axis P direction
1, the refraction angle of light in optical element 15 of injecting optical element 15 is made as θ
2, the diameter of light source 12 is made as D.
In addition, in Fig. 2, expansion shows Luminance Distribution and forms the 18a of structure portion, the 18a... of layer 18 dimension scale with respect to the base material 17 of optical element 15, and in fact, the size of the 18a of structure portion, 18a... is very little with respect to base material 17.
In addition, as shown in Figure 3, forming on the cross sectional shape of length direction quadrature of the 18a of structure portion, 18a... of layer 18 with Luminance Distribution, be contacted with the 18a of structure portion outer surface tangent line S and be made as tangential angle φ with the formed angle of face Q of optical axis P quadrature.At this moment, as shown in Figure 2, in tangential angle φ, the tangential angle of maximum is made as maximum tangential angle a, with the split image 12A of light source 12 apart from light source 12, with the direction of optical axis P quadrature on displacement be x.Displacement x is the distance apart from light source 12 end faces.
If adopt above each key element (parameter), then in surface illuminating device 10, following mathematical expression (1) to mathematical expression (3) is set up.
n
0sin(φ)＝nsin(φ-θ
2) ......(1)
n
0sinθ
1＝nsinθ
2 ......(2)
x＝Wtanθ
1+dtanθ
2 ......(3)
By adopting mathematical expression (1), calculate refraction angle θ by tangential angle φ substitution mathematical expression (1) arbitrarily to mathematical expression (3)
2, by the refraction angle θ that will calculate
2Substitution mathematical expression (2) is calculated refraction angle θ
1, by the θ that will calculate
1And θ
2Substitution mathematical expression (3) is calculated displacement x.Therefore, can determine the displacement x corresponding in a meaning ground, make the split image 12A of the light at the point of contact that arrives Luminance Distribution formation layer 18 move x to adjacent light source 12 with tangential angle φ with tangential angle φ.
Like this, the displacement x of split image 12A is determined by tangential angle φ, when in tangential angle φ, the tangential angle that the split image 12A of light source 12 is arrived L/2 is made as b, in tangential angle φ, the split image 12A of light source 12 reaches L, be the tangential angle at the center of adjacent light source 12 when being c, satisfy
x＝L/2-D/2 ......(4)
Tangential angle φ=tangential angle b.(L/2-D/2) be the position of central authorities in the heart in each of adjacent light source 12,12.Therefore, satisfy the tangential angle φ of following mathematical expression (5) if exist, then each split image 12A, 12A of adjacent light source 12,12 are overlapping.
x＞L/2-D/2 ......(5)
Like this, because satisfying the tangential angle φ of mathematical expression (5) exists, so each split image 12A, 12A of adjacent light source 12,12 are overlapping, this means that each split image 12A, 12A of then adjacent light source 12,12 are overlapping if exist mathematical expression (5) to set up so maximum tangential angle a in Luminance Distribution formation layer 18.
In surface illuminating device 10, be formed with optical element 15, so that exist mathematical expression (5) to set up so maximum tangential angle a in Luminance Distribution formation layer 18, each split image 12A, 12A of adjacent light source 12,12 are overlapping.
Fig. 4 is when being illustrated in from light transmission optical element 15 that single light source 12 penetrates, the curve map of the front luminance distribution under the state before seeing through diffuser plate 14.
As shown in Figure 4, front luminance distribution has the mountain type shape of general triangular shape, and promptly position intensity level (luminance level) is maximum directly over light source 12, and the position intensity level reduces directly over adjacent light source 12.In addition, front luminance distribution shown in Figure 4 is with respect to the front luminance distribution of triangle, and its shape has destruction slightly, and the destruction of this shape is based on the effect of the light that the plate 13 that is reflected reflected.
In addition, front luminance distribution during from light source 12 ejaculations is not limited in triangle, also can be that for example the summit has the general triangular shape (with reference to Fig. 5) of radian, has the shape (with reference to Fig. 6) of end difference at sloping portion, the shape (with reference to Fig. 7) of the gradient phasic Chang of sloping portion etc.
Fig. 8 be the expression when a plurality of light sources 12,12 ... split image 12A, 12A ... when overlapping, the curve map of the front luminance distribution state before the diffuser plate 14 when the light transmission distance W changes, front luminance distribution when Fig. 8 shows distance W in the design and relative therewith, distance W changes ± 8% o'clock front luminance distribution.
Front luminance distribution shown in Figure 8 is by Monte Carlo Method, to by reflecting plate 13, optical element 15 with based on the probability of optical characteristics to from light source 12,12 ... the light of output reflects, the state when refraction, scattering is simulated resulting result.
In Fig. 8, a light source 12 has intensity level maximum on position directly over this light source 12, the front luminance distribution that the position intensity level reduces directly over adjacent other light sources 12, on the position between adjacent two light sources 12,12, split image 12A, the 12A of these two light sources 12,12 are overlapping, and the part of each front luminance distribution is overlapping.
Under the nonoverlapping situation of split image 12A, 12A, when the distance W of light source 12 and optical element 15 changes, each light source 12,12 ... front luminance distribution the scope width ( light source 12,12 ... orientation on width) change, therefore, great changes will take place to cause front luminance distribution.For example, when distance W greater than the design on distance W the time, each light source 12,12 ... the scope width of front luminance distribution overlapping, otherwise, when distance W less than the design on distance W the time, adjacent light source 12,12 ... between intensity level on the position (centre position) reduce, thereby cause front luminance distribution to change a lot.
But, in surface illuminating device 10, because light source 12,12 ... split image 12A, 12A ... when for the design on distance W the time overlapping in advance, the part of each front luminance distribution is overlapped, therefore, can suppress with light source 12,12 ... the change of the intensity level relative with the variation of the distance W of optical element 15, as shown in Figure 8, even distance W changes, the variation of front luminance distribution is also very little, can suppress the generation of brightness disproportionation.
In addition, because can suppress by light source 12,12 ... and the generation of the brightness disproportionation that causes of the variation of the distance W of optical element 15, so can improve the configuration free degree of optical element 15 in framework 11, and the operability can realize improving the each several part assembling time.
And, light source 12,12 ... split image 12A, 12A ... the overlapping scope width that means front luminance distribution enlarges, even and have distance W and change, front luminance distribution itself also is difficult to the characteristic that changes.
Fig. 9 be expression light source 12,12 ... split image 12A, 12A ... when the only overlapping seldom part of the central portion of light source 12,12, the curve map of the front luminance distribution state before the diffuser plate 14 when the light transmission distance W changes, front luminance distribution when Fig. 9 shows distance W in the design and relative therewith, distance W changes ± 8% o'clock front luminance distribution.
Front luminance distribution shown in Figure 9 is by Monte Carlo Method with shown in Figure 8 the same, to reflect with probability based on optical characteristics, state when refraction, scattering simulates resulting result.
As shown in Figure 9, even light source 12,12 ... split image 12A, 12A ... during only overlapping seldom part, also can confirm: can suppress with light source 12,12 ... the change of the intensity level relative with the variation of the distance W of optical element 15, even distance W changes, the variation of front luminance distribution is also little, can suppress the generation of brightness disproportionation.Therefore, as above-mentioned, by light source 12,12 ... split image 12A, 12A ... overlapping and split image 12A, 12A ... the expansion of scope width of the front luminance distribution that expansion brought, thereby can realize the raising of the design freedom of distance W.
Below, show in surface illuminating device 10, be used to suppress the concrete example (with reference to Figure 10 to Figure 21) of the formation of brightness disproportionation.
Generally, in slim liquid crystal indicator, the diameter of light source (cold cathode fluorescent tube) is D=3.0mm～4.0mm, in the heart distance L=20mm～40mm in each of the light source of adjacent position, the distance W=6.0mm～16.0mm on the optical axis direction till from the light source center to the optical element.As optical element, can use mass-produced engineering plastics at a low price, the thickness d=0.3mm of optical element～2.0mm, refractive index n=1.50～1.63.The refractive index n of air
0Be roughly 1.0.
For example, when L=23.7mm, if W=11.7mm, D=3.0mm, then as shown in figure 10, if the split image of light source apart from light source, with the light shaft positive cross direction on displacement x=L/2-D/2=10.35mm or＞10.35mm, then the split image of light source is overlapping.
At this moment, if set d=0.4mm, n=1.585, then the tangential angle φ of optical element and displacement x are for passing through the shown in Figure 11 relation of mathematical expression (1) to mathematical expression (3).As shown in figure 11, the tangential angle of x=10.35mm is
Therefore, as the general parameter that slim liquid crystal indicator adopted, as L=23.7mm, W=11.7mm, D=3.0mm, d=0.4mm, n=1.585, n
0=1.0 o'clock, needing the Luminance Distribution of optical element to form layer was the shape with the maximum tangential angle a more than tangential angle φ=56 °.
As above-mentioned because can determine all parameters, be in the heart the refractive index n of air of thickness d, the distance W on the optical axis direction till from the light source center to the optical element, air layer of refractive index n, optical element of distance L, optical element in each of light source of adjacent position
0, light source diameter D, so can determine that the Luminance Distribution of optical element forms the needed shape of layer according to the tangential angle of utilizing mathematical expression (1) to be calculated to mathematical expression (3).
Table 1 shows in liquid crystal indicator, maximum (bmax) and the minimum of a value (bmin) of the tangential angle b that is calculated when generally the parameter that is adopted is in scope as described below, wherein, the scope of the general parameter that adopts is L=20mm～40mm, W=6.0mm～16.0mm, D=3.0mm～4.0mm, d=0.3mm～2.0mm, n=1.50～1.63.
For example, under the situation of L/W=3.0, when L=40mm, W=13.3mm, D=3.0mm, (L/2-D/2) expression maximum, and, when n=1.50, d=0.3mm, expression maximum (bmax).
Table 1
| L/W | bmin(°) | bmax(°) |
| 1.5 | 40 | 54 |
| 1.6 | 43 | 56 |
| 1.7 | 45 | 58 |
| 1.8 | 47 | 60 |
| 1.9 | 48 | 62 |
| 2.0 | 50 | 63 |
| 2.1 | 52 | 64 |
| 2.2 | 53 | 66 |
| 2.3 | 55 | 67 |
| 2.4 | 56 | 68 |
| 2.5 | 57 | 69 |
| 2.6 | 58 | 70 |
| 2.7 | 59 | 71 |
| 2.8 | 60 | 71 |
| 2.9 | 61 | 72 |
| 3.0 | 61 | 73 |
| 3.1 | 62 | 73 |
| 3.2 | 63 | 74 |
| 3.3 | 63 | 74 |
| 3.4 | 64 | 75 |
| 3.5 | 64 | 75 |
| 3.6 | 65 | 76 |
| 3.7 | 65 | 76 |
| 3.8 | 66 | 76 |
| 3.9 | 66 | 77 |
| 4.0 | 67 | 77 |
If form the maximum tangential angle a that exists in the layer 18 greater than the tangential angle b shown in the table 1 in Luminance Distribution, then light source 12,12 ... split image 12A, 12A ... overlapping, in surface illuminating device 10, be formed with optical element 15, so as Luminance Distribution form exist in the layer 18 such, greater than the maximum tangential angle a of the tangential angle b shown in the table 1.
Therefore, in surface illuminating device 10, because light source 12,12 ... split image 12A, 12A ... overlapping, therefore, even the distance W on the optical axis P direction till from the center of light source 12 to optical element 15 changes, the variation of front luminance distribution is also very little, also can suppress the generation of brightness disproportionation.
Preferred example is: as shown in figure 12, as front luminance distribution, position directly over two adjacent light sources 12,12 of the split image 12A of light source 12 arrival.In order to obtain such front luminance distribution, be maximum tangential angle a as long as satisfy the tangential angle φ of x=L-D/2, therefore, as long as the tangential angle c at the center of the split image 12A of light source 12 arrival adjacent light source 12 is identical with maximum tangential angle a.In addition, straight line T shown in Figure 12 represent each light source 12,12 of addition ... front luminance distribution and the front luminance distribution that obtains.
Maximum (cmax) and the minimum of a value (cmin) of tangential angle c represented in identical parameter L=20mm～40mm, W=6.0mm～16.0mm, D=3.0mm～4.0mm, d=0.3mm～2.0mm, n=1.50～1.63 when table 2 adopted with the numerical value of calculating table 1.
Table 2
| L/W | cmin(°) | cmax(°) |
| 1.5 | 61 | 73 |
| 1.6 | 63 | 74 |
| 1.7 | 64 | 75 |
| 1.8 | 65 | 76 |
| 1.9 | 66 | 76 |
| 2.0 | 67 | 77 |
| 2.1 | 67 | 78 |
| 2.2 | 68 | 78 |
| 2.3 | 68 | 78 |
| 2.4 | 69 | 79 |
| 2.5 | 69 | 79 |
| 2.6 | 70 | 80 |
| 2.7 | 70 | 80 |
| 2.8 | 70 | 80 |
| 2.9 | 71 | 80 |
| 3.0 | 71 | 81 |
| 3.1 | 71 | 81 |
| 3.2 | 71 | 81 |
| 3.3 | 72 | 81 |
| 3.4 | 72 | 81 |
| 3.5 | 72 | 81 |
| 3.6 | 72 | 82 |
| 3.7 | 72 | 83 |
| 3.8 | 72 | 84 |
| 3.9 | 72 | 84 |
| 4.0 | 72 | 84 |
Therefore, have the maximum tangential angle a identical in the layer 18 with the tangential angle c shown in the table 2 if form in Luminance Distribution, then light source 12,12 ... split image 12A, 12A ... each light source 12,12 ... between whole region overlapping.
In addition, in order to obtain front luminance distribution shown in Figure 12, when the intensity level of position directly over the light source 12 is 1, need this light source 12 split image 12A, and adjacent light source 12 between the intensity level of central authorities be 0.4～0.6 degree of half roughly, and the intensity level directly over the adjacent light source 12 is roughly 0.Therefore, need the maximum tangential angle a of optical element 15 and the tangential angle c shown in the table 2 roughly the same, and, Luminance Distribution form comprise on the layer 18 40%～60%, tangential angle is more than the b and less than the part of c.As above-mentioned, tangential angle b is the angle that the split image 12A of light source 12 arrives L/2, and tangential angle c is the angle that the split image 12A of light source 12 arrives L.
In surface illuminating device 10, be formed with optical element 15, exist and the roughly the same maximum tangential angle a of tangential angle c as shown in table 2 like this so that form on the layer 18 in Luminance Distribution, and Luminance Distribution form comprise on the layer 18 40%～60%, tangential angle is more than the b and less than the part of c.
Therefore, in surface illuminating device 10, because light source 12,12 ... split image 12A, 12A ... each light source 12,12 ... between whole region overlapping, therefore, even the distance W of the optical axis P direction till from the center of light source 12 to optical element 15 changes, the variation of front luminance distribution is also very little, also can suppress the generation of brightness disproportionation.
Figure 13 is that expression is with respect to distance W=1 on the optical axis direction till from the light source center to the optical element, when the diameter of light source is refractive index n=1.585 of D=0.25, W/D=4, optical element, the thickness d of optical element=0.4mm, the curve map of the relation between the displacement x of maximum tangential angle a and split image.
As shown in figure 13, if displacement x increases, then the rate of change of maximum tangential angle a also increases.If distance L in each of adjacent position light source in the heart than the ratio of the distance W on the optical axis direction till from the light source center to the optical element, be that L/W increases, then displacement x also increases, therefore, if L/W increases, the variable quantity of then relative with the variation of maximum tangential angle a displacement x also increases.
Like this, if the rate of change of maximum tangential angle a increases, then be difficult to form Luminance Distribution and form layer.Therefore, if L/W increases, then be difficult to form Luminance Distribution and form layer, and be difficult to control maximum tangential angle a.
The scope that can control maximum tangential angle a be L/W in the scope below 2.5, the L/W in table 2 can suitably suppress the generation of brightness disproportionation in the scope below 2.5.
Figure 14 and Figure 15 represent the curve map of the front luminance distribution under the state of the light transmission optical element 15 that penetrates from light source 12 and diffuser plate 14.Figure 14 be with Fig. 8 in design on distance W the time the corresponding curve map of front luminance distribution, Figure 15 be with Fig. 9 in design on distance W the time the corresponding curve map of front luminance distribution.
As Figure 14 and shown in Figure 15, because the diffusion of diffuser plate 14 is seeing through under the state of diffuser plate 14, front luminance distribution is homogeneous roughly.
Like this, by adopting diffuser plate 14, can realize the homogenization of front luminance distribution, and can prevent the generation of brightness disproportionation.
As above-mentioned, by adopting diffuser plate 14, can realize the homogenization of front luminance distribution, therefore, from light source 12,12 ... under the state before the light transmission diffuser plate of ejaculation 14, as long as the maximum of the intensity level of front luminance distribution and minimum of a value do not produce very big poor, just can realize the homogenization of front luminance distribution.
If consider the effect of diffuser plate 14, the ratio that then can realize the maximum of intensity level of homogenization of front luminance distribution and minimum of a value according to the effect of diffuser plate 14 is for allowing for example scope more than 0.7.
Figure 16 and Figure 17 represent to have inquired into the generation state of brightness disproportionation to adding up to 23 samplings, and expression tangential angle φ is illustrated in Luminance Distribution and forms the curve map that comprises the ratio of this tangential angle φ in the layer on the longitudinal axis on transverse axis.
The data of Figure 16 and Figure 17 and Figure 13 are the same, be expression with respect to distance W=1 on the optical axis direction till from the center of light source to optical element, during the thickness d of diameter D=0.25, the W/D=4 of light source, refractive index n=1.585 of optical element, optical element=0.4mm, the curve map of the relation between the ratio of tangential angle φ and this tangential angle φ.In addition, light source in each in the heart distance L than the ratio of distance W, be L/W=2.0, the light transmission rate of diffuser plate is 60%.
Figure 16 shows 11 samplings (related data of A～K), these 11 samplings are that the maximum of the intensity level in the light transmission diffuser plate front luminance distribution before and the ratio of minimum of a value are more than 0.7, the incidence of brightness disproportionation is little, and has guaranteed the sampling of the homogeneity of front luminance distribution.
On the other hand, Figure 17 shows 12 samplings (related data of L～W), these 12 samplings be the ratio of the maximum of the intensity level before the light transmission diffuser plate and minimum of a value less than 0.7, the incidence height of brightness disproportionation, and fail to guarantee the sampling of the homogeneity of front luminance distribution.
As shown in figure 16, the data representation that the incidence of brightness disproportionation is low: form in the layer in the Luminance Distribution of all samplings and to comprise part, and comprise the above part (R shown in Figure 16) of tangential angle b (=56 °) among 10%～30% tangential angle φ roughly with the tangential angle φ more than tangential angle b=56 °.
On the other hand, in the high data of the incidence of brightness disproportionation shown in Figure 17, except that two samplings, can surpass the above part of 30% sampling (T, V, W) or tangential angle b less than the sampling (L, M, N, O, P, Q) of tangential angle b (=56 °), the above part of tangential angle b by maximum tangential angle a and constitute less than 10% sampling (R).
As Figure 16 and shown in Figure 17, can confirm: during part more than the tangential angle b in comprising 10%～30% tangential angle φ (=56 °), the maximum of the intensity level in the front luminance distribution before the light transmission diffuser plate and the ratio of minimum of a value are more than 0.7, thereby can suppress brightness disproportionation.Therefore, the Luminance Distribution that is formed with optical element 15 forms layer 18, so that comprise the above part of tangential angle b among 10%～30% tangential angle φ, thereby can suppress brightness disproportionation.
Figure 18 represents the front luminance distribution under the state that the light transmission optical element 15 that penetrates from light source and Luminance Distribution form layer 18.As shown in figure 18, when the split image 12A that makes light source 12 be positioned at adjacent light source 12 directly over the time (with reference to Figure 12), even under the state that diffuser plate 14 is not set, also can guarantee the homogeneity of front luminance distribution.But, particularly when L/W is bigger value, needs to form accurately Luminance Distribution and form layer 18 with big tangential angle φ more than tangential angle φ, for example tangential angle b=56 °.
But, as above-mentioned, because be provided with the diffuser plate 14 that is used to spread through the light of optical element 15, so under the state before the light transmission diffuser plate 14, even position directly over the split image 12A no show adjacent light source 12 of light source 12, also can be seeing through under the state of diffuser plate 14, by the effect of diffuser plate 14, make split image 12A be positioned at adjacent light source 12 directly over.Therefore, when being provided with diffuser plate 14, can not estimate the size of L/W, and realize forming the necessity reduction that the Luminance Distribution with big tangential angle φ forms layer 18, and be convenient to make optical element 15 with high accuracy.
In addition, when not being provided with diffuser plate 14, though for the split image 12A that makes light source 12 overlapping continuously mutually, and the Luminance Distribution that preferably makes optical element 15 forms the 18a of structure portion in the layer 18,18a, ... outer surface form curve form, but, when being provided with diffuser plate 14, because can dwindle the displacement x of split image 12A, and, even split image 12A is discontinuous, also can form level and smooth (smooth) Luminance Distribution according to the effect of diffuser plate 14, so can make the 18a of structure portion, 18a, ... the outer surface part that forms polygonal shape for example or its outer surface be plane shape, thereby can realize being convenient to the manufacturing of optical element 15.
Figure 19 for example shows when being provided with diffuser plate 14, the 18a of structure portion, 18a ... at least a portion form the example of plane optical element 15.
In example shown in Figure 19, constitute three 18b of structure portion, 18c, 18d and be one group tectosome, this tectosome is continuously and form a plurality of.
In example shown in Figure 19, L/W=2.0, in Luminance Distribution formation layer 18, comprise 10%～15% tangential angle b=56 ° with top, form in Luminance Distribution and to comprise the part of 0 ° of 10%～20% tangential angle in the layer 18, promptly form plane part, and the 18c of structure portion and the 18d of structure portion form the polygonal shape with respect to light shaft positive cross.
Figure 20 represents that about optical element shown in Figure 19 15 expression tangential angle φ is illustrated in Luminance Distribution and forms the curve map that comprises the ratio of this tangential angle φ in the layer 18 on the longitudinal axis on transverse axis.As shown in figure 20, optical element 15 as shown in figure 19 forms in Luminance Distribution and comprises 10%～15% tangential angle in the layer 18 and be about part more than 56 °.
Figure 21 shows the example about Figure 19 and Figure 20, from light source 12,12 ... the front luminance distribution under the state of the light transmission diffuser plate 14 of ejaculation.At this moment, the transmitance of the light of diffuser plate 14 is 60%.As shown in figure 21, can confirm: according to the diffusion of diffuser plate 14 and diffused light, thereby can guarantee the homogeneity of front luminance distribution, and can suppress brightness disproportionation.
Therefore, though the Luminance Distribution that makes optical element 15 form layer 18 the 18a of structure portion, 18a ... outer surface form polygonal shape or its part under the plane situation, also can suppress brightness disproportionation by adopting diffuser plate 14.
In addition, in surface illuminating device 10, for example optical element bodies 16 such as diffusion sheet, prismatic lens, reflective polarizer are configured in the opposite side of optical element 15, optical element body 16 and optical element 15 clip diffuser plate 14, therefore, the light that is spread by diffuser plate 14 by optical element body 16 further spread, scattering etc., thereby can realize improving the effect that suppresses brightness disproportionation.
Below, to making optical element 15 and diffuser plate 14 incorporate structures, being that the optical element package body describes (with reference to Figure 22 and Figure 23).
As above-mentioned, though in surface illuminating device 10, from light source 12,12 ... side disposes optical element 15, diffuser plate 14 and optical element body 16 successively, probably because the thickness of these each several parts causes the rigidity reduction, warpage or bending etc. can take place, thereby cause the generation brightness disproportionation.
In order to prevent such warpage or crooked generation, can constitute package body 21, this package body 21 forms by the following method: pack optical element 15 and diffuser plate 14 or optical element 15 and diffuser plate 14 and optical element body 16 (with reference to Figure 22) by package members such as slide or transparent membrane 20.
In addition, for example, also can engage optical element 15 and diffuser plate 14 constitutes optical element package body 22 (with reference to Figure 23) by uv-hardening resin or pressure sensitive adhesive etc.In this case, also can on the basis that engages optical element 15 and diffuser plate 14, optical element body 16 also be engaged on the diffuser plate 14, thereby constitute optical element package body 22.
By constituting optical element package body 21 or optical element package body 22, can increase thickness and improve rigidity, thus the generation of the warpage of preventing or bending etc.
Below, the Luminance Distribution that shows optical element 15 forms the example (with reference to Figure 24 to Figure 29) of the cross sectional shape of layer 18.
The cross sectional shape (shape of outer surface) that forms layer 18 by the Luminance Distribution that makes optical element 15 forms desired curve form, thereby can suppress brightness disproportionation, still, as above-mentioned, form curve form for making Luminance Distribution form layer 18, have the problem of processing difficulties mostly.So, form layer 18 by making polygonal shape described as follows form Luminance Distribution as approximate curve form, can on the basis of guaranteeing good processability, suppress the generation of brightness disproportionation.
Figure 24 shows the example 100 that the Luminance Distribution with such polygonal shape forms layer 18.
Luminance Distribution formation layer 100 constitutes and comprises: outer surface 101, and parallel with the orientation of light source; And outside 102,102,103,103 ..., 107,107, be benchmark with this outer surface 101, along with near light source, its angle of inclination with respect to the orientation of light source increases gradually.Luminance Distribution formation layer 100 is a benchmark with the M of Central Line of the point of leap bisection outer surface 101, is the shape of line symmetry in the orientation of light source.Therefore, Luminance Distribution forms layer 100 and forms: when set successively each outer surface 101,102,103 ... with respect to the angle of inclination of the orientation of light source be s1, s2, s3 ... during s7, s1＜s2＜s3＜...＜s7.
Though Luminance Distribution forms layer 100 and is formed by 13 outer surfaces (line segment) with different angles,, the quantity of outer surface is not limited in 13, can consider the distance L between light source and the diameter D of light source etc. and at random determines the quantity of outer surface.
By adopt as shown in figure 24, cross sectional shape forms layer 18 for the Luminance Distribution of the polygonal shape of approximate curve form, owing to there is no need to form the curve form of making difficulty, it is hereby ensured the good processability of optical element.
Figure 25 and Figure 26 show the polygonal shape of cutting apart as shown in figure 24 and form the cambial example 200,300 of Luminance Distribution of a plurality of structure portion.
Luminance Distribution shown in Figure 25 forms layer 200 and forms by repeatedly arranging two 200a of structure portion, 200b alternately.
The 200a of structure portion for example has seven outer surfaces, is made of outer surface 201,202,202,203,203,204,204, and the 200b of structure portion also for example has seven outer surfaces, is made of outer surface 205,206,206,207,207,208,208.
Outer surface 201,205 is parallel with the orientation of light source, forms respectively with Luminance Distribution and forms the identical angle of inclination of angle of inclination s1 in layers 100.Outer surface 202,203,204 is identical with angle of inclination s3, s5, the s7 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation, and outer surface 206,207,208 is identical with angle of inclination s2, s4, the s6 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation.
Like this, by adopt by cut apart the 200a of structure portion that Luminance Distribution forms the shape of layer 100,200b, 200a, 200b ... the Luminance Distribution of formation forms layers 200, thereby because the quantity of the outer surface of the 200a of structure portion, 200b is few, so can be easy to carry out the processing of optical element.
Luminance Distribution shown in Figure 26 forms layer 300 and comprises repeatedly mutual two 300a of structure portion, 300b that arrange.
The 300a of structure portion for example has six outer surfaces, is made of outer surface 301,301,302,302,303,303, and the 300b of structure portion also for example has six outer surfaces, is made of outer surface 304,304,305,305,306,306.
Outer surface 301,302,303 is identical with angle of inclination s3, s5, the s7 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation, and outer surface 304,305,306 is identical with angle of inclination s2, s4, the s6 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation.
Between 300a of structure portion and 300b, be formed with the parallel surface parallel 307 with the light source orientation.Parallel surface 307 is to be equivalent to the face that Luminance Distribution forms the outer surface 101 of layer 100.
Like this, by adopt by cut apart the 300a of structure portion that Luminance Distribution forms the shape of layer 100,300b, 300a, 300b ... the Luminance Distribution of formation forms layers 300, because the quantity of the outer surface of the 300a of structure portion, 300b is few, so can be easy to carry out the processing of optical element.
In addition, adopting Luminance Distribution to form layer 300 o'clock, as shown in figure 27, when for example forming optical element by the injection molding that adopts metal pattern 1000, in metal pattern 1000, between the part of shaping structure 300a of portion and the 300b of structure portion, there is teat 1001, still, this teat 1001 has certain width in the orientation of light source, so the rigidity height.Therefore, teat 1001 is difficult to deform, thereby can successfully carry out the demoulding of metal pattern 1000, and can realize improving the machining accuracy that Luminance Distribution after the shaping forms layer 300.
Figure 28 and Figure 29 show and are divided into three cambial examples 400,500 of triangular shaped Luminance Distribution.
Luminance Distribution shown in Figure 28 forms layer 400 and forms by repeatedly arranging three 400a of structure portion, 400b, 400c successively.
The 400a of structure portion, 400,400c for example has five outer surfaces respectively, the outer surface 401 of the 400a of structure portion, 402,403 form angle of inclination s1 in the layer 100 with Luminance Distribution respectively with respect to the angle of inclination of light source orientation, s3, s6 is identical, the outer surface 404 of the 400b of structure portion, 405,406 form angle of inclination s1 in the layer 100 with Luminance Distribution respectively with respect to the angle of inclination of light source orientation, s4, s7 is identical, the outer surface 407 of the 400c of structure portion, 408,409 form angle of inclination s1 in the layer 100 with Luminance Distribution respectively with respect to the angle of inclination of light source orientation, s2, s5 is identical.
Like this, form layers 400 by adopting by cutting apart the 400a of structure portion that Luminance Distribution forms the shape of layer 100, Luminance Distribution that 400b, 400c constitute, because the quantity of the outer surface of the 400a of structure portion, 400b, 400c is few, so can be easy to carry out the processing of optical element.
Luminance Distribution shown in Figure 29 forms layer 500 and forms by repeatedly arranging three 500a of structure portion, 500b, 500c successively.
The 500a of structure portion, 500b, 500c for example have four outer surfaces respectively, the outer surface 501,502 of the 500a of structure portion is identical with angle of inclination s3, the s6 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation, the outer surface 503,504 of the 500b of structure portion is identical with angle of inclination s4, the s7 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation, and the outer surface 505,506 of the 500c of structure portion is identical with angle of inclination s2, the s5 that Luminance Distribution forms in the layer 100 respectively with respect to the angle of inclination of light source orientation.
Between the 500a of structure portion, 500b, 500c, form parallel with the light source orientation respectively parallel surface 507,507.Parallel surface the 507, the 507th is equivalent to the face that Luminance Distribution forms the outer surface 101 of layer 100.
Like this, form layers 500 by adopting by cutting apart the 500a of structure portion that Luminance Distribution forms the shape of layer 100, Luminance Distribution that 500b, 500c constitute, because the quantity of the outer surface of the 500a of structure portion, 500b, 500c is few, so can be easy to carry out the processing of optical element.
In addition, even adopting Luminance Distribution to form under the situation of layer 500, also with to adopt Luminance Distribution to form layer 300 o'clock the same, because the rigidity height of the teat of metal pattern, so can realize improving the machining accuracy that Luminance Distribution after the shaping forms layer 500.
In addition, show the cambial example of Luminance Distribution with two or three structure portions of repeatedly arranging successively above, still, the number of cutting apart of polygonal shape is not limited in two or three, also can be more than four.These structures are the structures that the polygonal shape are divided into a plurality of structure portion, and forming layer 100 with the Luminance Distribution of cutting apart on optical characteristics does not have big difference, can select to consider the structure of processability arbitrarily.
Figure 30 is the analog result of expression as the front luminance distribution of an optical element example, that have Luminance Distribution formation layer 300, is the curve map corresponding with Fig. 4.
Front luminance distribution has the shape of roughly mountain described as follows type: position intensity level maximum directly over light source 12, towards other adjacent light source 12,12 ... directly over the position intensity level reduce.
Figure 31 is illustrated in the front luminance distribution when lighting whole light source among Figure 30, is the curve map corresponding with Figure 18.
If Figure 30 and result shown in Figure 31 and Fig. 4 and result shown in Figure 180 are compared, though then produced small brightness disproportionation on the whole, but, this brightness disproportionation is with to exist with ... space between light sources uneven different from the light source of L, by configuration diffuser plate or diffusion sheet etc., can control brightness disproportionation until in practicality, not having problems.
At the concrete shape and the structure of the each several part shown in the above preferred embodiment, be an example of specializing of implementing when of the present invention, can not do determinate explanation to technical scope of the present invention according to these.
Claims (16)
1. surface illuminating device comprises: a plurality of light sources, each described light source form to prescribed direction extend cylindric, under the state that extends to same direction, be configured at grade; Optical element has light transmission, and is formed with Luminance Distribution and forms layer, and described Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of described light sources; And reflecting surface, be positioned at the opposite side of described optical element in the mode that clips a plurality of described light sources, air layer is between described reflecting surface and described optical element, and, described reflecting surface is used to reflect the light that penetrates from described light source, and in described surface illuminating device, the Luminance Distribution of described optical element forms that layer is extended by the length direction to described light source and constitutes to the outstanding a plurality of structure portion of described optical axis direction, described surface illuminating device is characterised in that, comprising:
Described optical element comprises maximum tangential angle a,
Wherein, for described maximum tangential angle a,
When each distance between centers with the described light source of adjacent position is made as L,
The refractive index of described optical element is made as n,
The thickness of described optical element is made as d,
Distance on the optical axis direction till will be from described light source center to described optical element is made as W,
The air refraction of described air layer is made as n
0,
The light that will penetrate and inject described optical element from described light source is made as θ with respect to the angle of injecting of optical axis direction
1,
The refraction angle of light in described optical element of injecting described optical element is made as θ
2,
The diameter of described light source is made as D,
Will with the cross sectional shape of the length direction quadrature of the cambial structure of described Luminance Distribution portion in, the tangent line that contacts with the cambial outer surface of described Luminance Distribution and be made as tangential angle φ with the formed angle of the face of described light shaft positive cross,
Tangential angle maximum among the described tangential angle φ is made as maximum tangential angle a,
And by following conditions formula (1) to conditional (3), the split image of calculating described light source with described light shaft positive cross direction under the situation apart from the displacement x of light source,
Described maximum tangential angle a satisfies x＞L/2-D/2,
n
0sin(a)＝nsin(a-θ
2)......(1)
n
0sinθ
1＝nsinθ
2......(2)
x＝Wtanθ
1+dtanθ
2......(3)。
2. surface illuminating device according to claim 1 is characterized in that,
Distance L be 20mm～40mm,
Refractive index n is 1.50～1.63,
Thickness d be 0.3mm～2.0mm,
Distance W be 6.0mm～16.0mm,
Diameter D is in the scope of 3.0mm～4.0mm,
When L/W=1.5～1.7 and b=40 °～58 °,
L/W=1.7～1.9 and b=45 °～62 °,
L/W=1.9～2.1 and b=48 °～64 °,
L/W=2.1～2.3 and b=52 °～67 °,
L/W=2.3～2.5 and b=55 °～69 °,
L/W=2.5～2.7 and b=57 °～71 °,
L/W=2.7～2.9 and b=59 °～72 °,
L/W=2.9～3.1 and b=61 °～73 °,
L/W=3.1～3.3 and b=62 °～74 ° or
In the time of L/W=3.3～3.5 and b=63 °～75 °,
In described tangential angle φ, if arriving the described tangential angle of L/2, the split image of described light source is made as b, then described maximum tangential angle a is greater than tangential angle b.
3. surface illuminating device according to claim 1 is characterized in that, described surface illuminating device comprises:
Described optical element comprises the described maximum tangential angle a that satisfies x=L-D/2.
4. surface illuminating device according to claim 3 is characterized in that,
Distance L be 20mm～40mm,
Refractive index n is 1.50～1.63,
Thickness d be 0.3mm～2.0mm,
Distance W be 6.0mm～16.0mm,
Diameter D is in the scope of 3.0mm～4.0mm,
When L/W=1.5～1.7 and c=61 °～75 °,
L/W=1.7～1.9 and c=64 °～76 °,
L/W=1.9～2.1 and c=66 °～78 ° or
In the time of L/W=2.1～2.3 and c=67 °～78 °,
In described tangential angle φ, the tangential angle that arrives L as if the split image with described light source is made as c, and then described maximum tangential angle a and tangential angle c are roughly the same,
Described surface illuminating device comprises: described optical element, described Luminance Distribution form comprise in the layer 40%～60% more than or equal to b and less than the part of c.
5. surface illuminating device according to claim 1 is characterized in that,
To clip the mode of described optical element with described light source, at the opposite side configuration diffuser plate of described light source,
Described surface illuminating device comprises: described optical element, and when in described tangential angle φ, the tangential angle that the split image of described light source is arrived L/2 is made as b,
D/W is 0.19～0.3 5,
L/W is 1.9～3.5 o'clock,
Form in the layer in described Luminance Distribution, described optical element comprises the part greater than b among 10%～30% the tangential angle φ.
6. surface illuminating device according to claim 5 is characterized in that,
Clipping the mode of described optical element with described light source, described diffuser plate is configured in the opposite side of described light source,
The light transmission rate of described diffuser plate is 55%～65%, and thickness is more than the 1mm.
7. surface illuminating device according to claim 5 is characterized in that,
When L/W is 2.0, form to form in the layer in the described Luminance Distribution of described optical element and comprise that 10%～15% described tangential angle φ is the part more than 56 °, and comprise that 10%～20% described tangential angle φ is 0 ° a part,
The thickness of described optical element is 0.2mm～0.4mm,
The light transmission rate of described diffuser plate is 55%～65%.
8. surface illuminating device according to claim 1 is characterized in that,
Clipping the mode of described optical element with described light source, dispose described diffuser plate at the opposite side of described light source,
To clip the mode of described diffuser plate with described optical element, at the couple positioned opposite of described optical element other at least one optical element different with described optical element,
Be provided with the optical element package body in described surface illuminating device, described optical element package body is by package member, described diffuser plate and each described optical element of being disposed at described diffuser plate both sides is respectively packed form.
9. surface illuminating device according to claim 1 is characterized in that,
To clip the mode of described optical element with described light source, at the opposite side configuration diffuser plate of described light source,
Be provided with the optical element package body in described surface illuminating device, described optical element package body is by engaging described diffuser plate and described optical element forms.
10. surface illuminating device according to claim 1 is characterized in that,
The outer surface of cambial each the structure portion of described Luminance Distribution forms curve form.
11. surface illuminating device according to claim 1 is characterized in that,
The outer surface of cambial each the structure portion of described Luminance Distribution forms the polygonal shape.
12. surface illuminating device according to claim 11 is characterized in that,
Described each structure portion forms the shape of line symmetry in the orientation of described light source, and described each structure portion forms: with respect to the angle of inclination of each outer surface of described light source orientation along with increasing gradually near described light source.
13. surface illuminating device according to claim 12 is characterized in that,
Between described each structure portion, be formed with plane with light shaft positive cross.
14. surface illuminating device according to claim 1 is characterized in that,
On described reflecting surface, equally spaced dispose a plurality of described light sources.
15. optical element, be formed with Luminance Distribution and form layer, described Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of light sources, each described light source forms to the cylindric of prescribed direction extension and is being configured at grade under the state that extends to same direction, described Luminance Distribution forms that layer is extended by the length direction to described light source and constitutes to the outstanding a plurality of structure portion of described optical axis direction, described optical element is characterised in that
Described optical element comprises: maximum tangential angle a, and when each distance between centers with the described light source of adjacent position is made as L,
The refractive index of described optical element is made as n,
The thickness of described optical element is made as d,
Distance on the optical axis direction till will be from described light source center to described optical element is made as W,
The air refraction of described air layer is made as n
0,
The light that will penetrate and inject described optical element from described light source is made as θ with respect to the angle of injecting of optical axis direction
1,
The refraction angle of light in described optical element of injecting described optical element is made as θ
2,
The diameter of described light source is made as D,
Will with the cross sectional shape of the length direction quadrature of the cambial structure of described Luminance Distribution portion in, the tangent line that contacts with the cambial outer surface of described Luminance Distribution and be made as tangential angle φ with the formed angle of the face of described light shaft positive cross,
Tangential angle maximum among the described tangential angle φ is made as maximum tangential angle a,
And by following conditions formula (1) to conditional (3), the split image of calculating described light source with described light shaft positive cross direction under the situation apart from the displacement x of light source,
Described maximum tangential angle a satisfies x＞L/2-D/2,
n
0sin(a)＝nsin(a-θ
2)......(1)
n
0sinθ
1＝nsinθ
2......(2)
x＝Wtanθ
1+dtanθ
2......(3)。
16. a liquid crystal indicator comprises: a plurality of light sources, each described light source form to prescribed direction extend cylindric, under the state that extends to same direction, be configured at grade; Optical element, has light transmission, and be formed with Luminance Distribution and form layer, described Luminance Distribution forms layer and is used to suppress the luminance deviation of light on optical axis direction that penetrate from a plurality of described light sources, and described Luminance Distribution forms that layer is extended by the length direction to described light source and constitutes to the outstanding a plurality of structure portion of described optical axis direction; Reflecting surface is positioned at the opposite side of described optical element in the mode that clips a plurality of described light sources, and air layer is between described reflecting surface and described optical element, and described reflecting surface is used to reflect the light that penetrates from described light source; And liquid crystal panel, being used for display image, and shining the light that has from a plurality of described light sources ejaculations, described liquid crystal indicator is characterised in that, comprising:
Described optical element comprises maximum tangential angle a,
Wherein, for described maximum tangential angle a,
When each distance between centers with the described light source of adjacent position is made as L,
The refractive index of described optical element is made as n,
The thickness of described optical element is made as d,
Distance on the optical axis direction till will be from described light source center to described optical element is made as W,
The air refraction of described air layer is made as n
0,
The light that will penetrate and inject described optical element from described light source is made as θ with respect to the angle of injecting of optical axis direction
1,
The refraction angle of light in described optical element of injecting described optical element is made as θ
2,
The diameter of described light source is made as D,
Will with the cross sectional shape of the length direction quadrature of the cambial structure of described Luminance Distribution portion in, the tangent line that contacts with the cambial outer surface of described Luminance Distribution and be made as tangential angle φ with the formed angle of the face of described light shaft positive cross,
Tangential angle maximum among the described tangential angle φ is made as maximum tangential angle a,
And by following conditions formula (1) to conditional (3), the split image of calculating described light source with described light shaft positive cross direction under the situation apart from the displacement x of light source,
Described maximum tangential angle a satisfies x＞L/2-D/2,
n
0sin(a)＝nsin(a-θ
2)......(1)
n
0sinθ
1＝nsinθ
2......(2)
x＝Wtanθ
1+dtanθ
2......(3)。
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006206008 | 2006-07-28 | ||
| JP206008/2006 | 2006-07-28 | ||
| JP171078/2007 | 2007-06-28 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101351671A true CN101351671A (en) | 2009-01-21 |
| CN100591985C CN100591985C (en) | 2010-02-24 |
Family
ID=40269701
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200780001019A Expired - Fee Related CN100591985C (en) | 2006-07-28 | 2007-07-25 | Planar light emitting device, optical element and liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100591985C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103090203A (en) * | 2011-10-28 | 2013-05-08 | 鸿富锦精密工业（深圳）有限公司 | Plane lighting device |
| CN113866855A (en) * | 2021-10-23 | 2021-12-31 | 广东瑞捷光电股份有限公司 | Structural diffusion plate and preparation method thereof |
-
2007
- 2007-07-25 CN CN200780001019A patent/CN100591985C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103090203A (en) * | 2011-10-28 | 2013-05-08 | 鸿富锦精密工业（深圳）有限公司 | Plane lighting device |
| CN113866855A (en) * | 2021-10-23 | 2021-12-31 | 广东瑞捷光电股份有限公司 | Structural diffusion plate and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100591985C (en) | 2010-02-24 |
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