CN100426009C - Light conducting board and background device - Google Patents

Abstract

The present invention relates to a light guide plate and a back light device which adopts the light guide plate. The light guide plate comprises a first surface, a second surface which is opposite to the first surface, a plurality of side surfaces and a plurality of diffusing units, wherein the second surface is a light emergent surface, the diffusing units are arranged on the first surface, at least one of the side surfaces is a light incident surface, and other side surfaces are light reflection side surfaces. A projected area of each diffusing unit on the first surface is in direct proportion to the square sum of reciprocals of the distances between the diffusing unit and coordinate points in at least one linear coordinate point set in or out of the side surfaces as well as between the diffusing unit and the coordinate points in a mirror image linear coordinate point set formed by the coordinate points on the light reflection side surfaces. The diffusing units can improve the light emergent uniformity of the light guide plate which is matched with a linear light source and the back light device which adopts the light guide plate.

Description

Light guide plate and back lighting device

[technical field]

The present invention relates to the back lighting device of a kind of light guide plate and this light guide plate of employing.

[background technology]

Because the liquid crystal itself in the panel of LCD is not had a characteristics of luminescence, so,, need to give the LCD panel that one planar light source device is provided for reaching display effect, as back lighting device, its function is area source abundant to panel of LCD supply briliancy and that be evenly distributed.

The prior art back lighting device mainly is made up of light source, light guide plate, reflecting plate, diffuser plate and prism plate.Wherein, this light source can be arranged at light guide plate one side or two opposite sides and with light emission to this light guide plate.The effect of this light guide plate is the transmission direction of direct light line, makes light by the even outgoing of the exiting surface of light guide plate.Because the light that light source sends is to enter from the light guide plate side, so light guide plate is brighter near the part of light source, and darker away from the part of light source, therefore, for increasing the light extraction efficiency and the uniformity coefficient of light guide plate, the one side in light guide plate is provided with V-shaped groove or configuration light diffusion site usually.When light transmission during to V-shaped groove or light diffusion site, reflection and scattering will take place in light, and to each different directions transmission, finally by the exiting surface ejaculation of light guide plate.Utilize various densitys, the V-shaped groove that varies in size or light diffusion site, can make light guide plate luminous evenly.

A kind of prior art back lighting device with bottom surface network point distribution as depicted in figs. 1 and 2, it is exposed in No. the 5th, 363,294, the United States Patent (USP) of 8 bulletins November in 1994.The back lighting device that this patent discloses comprises a light guide plate 22, a line source 21, a diffuser plate 27 and two reflecting plates 25,29.This light guide plate 22 comprises a light entrance face 223, light-emitting face 221, end face 224 and bottom surface 222, this line source 21 is positioned at this light guide plate 22 light entrance faces 223 1 sides, this reflecting plate 29 is arranged at this end face 224 1 sides, these diffuser plate 27 relative these light-emitting faces 221 are provided with, and these reflecting plate 25 relative these bottom surfaces 222 are provided with.Wherein, one reflection lampshade 28 is set around this line source 21 for the light that effectively utilizes line source 21 to be sent.These light guide plate 22 bottom surfaces are provided with a plurality of sites 26 that the ranks shape is arranged that are.

Seeing also Fig. 2, is the distribution schematic diagram of this site 26 in these light guide plate 22 bottom surfaces 222.The direction of these 26 edges, site and line source 21 axially parallels is lined up multiple row, and site 26 big or small identical in each row.Multirow is lined up with line source 21 axial vertical directions in these 26 edges, site, and the varying in size of site 26 in each row, wherein, near site 26 minimums of line source 21, along with and line source 21 between the increase of distance, this site 26 becomes big gradually by linear relationship.Owing to the increase along with transmission range of the intensity of line source 21 emitted lights reduces, and light guide plate 22 is posted reflecting plate 29 (as shown in Figure 1) away from an end face of line source 21,29 pairs of reflections that are incident upon its glazed thread of this reflecting plate, causing these light guide plate 22 interior light intensities is not to reach minimum at the end face 224 away from line source 21, and its minimum light line strength present position is between light entrance face 223 and end face 224 and near this end face 224.The minimum place of the size of this site 26 light intensity in this light guide plate 22 reaches maximum, and thereupon with constant size distribution to the end face 224 of this light guide plate 22 away from line source 21.

This light guide plate 22 can solve near the part of line source 21 luminous brighter substantially, and away from the luminous darker technical matters of line source 21 parts, but, because these light guide plate 22 end faces 224 are provided with reflecting plate 29, it is with in the light reflected back light guide plate 22 of incident on it, causing near these light guide plate 22 end faces 224 actual light line strengths is not to be constant size distribution, but the most close end face 224 place's light intensities are than the part away from end face 224 is big slightly, this is called the edge reflection effect, so near the constant size distribution of this site 26 end face 224 can not make these light guide plate 22 bright dippings even.Equally, also there is the edge reflection effect problem in light guide plate near 22 sides 225, and row can not make these light guide plate 22 bright dippings even to the constant size distribution of the site 26 of arranging.

In addition, because the light that sends of line source 21 is in light guide plate 22 in the transmission course, usually repeatedly reflection between light guide plate 22 light-emitting faces 221 and bottom surface 222, its light guide plate 22 from light source 21 to end face near 224 partly actual light line strength be not to be the linear relationship variation.Because line source 21 has certain-length, the light that light guide plate 22 is accepted near the part at line source 21 centers is more than the part near line source 21 two ends, and, low in the middle of the brightness ratio of line source 21 two ends near the electrode part, cause light guide plate 22 lower than the luminosity of close line source 21 cores near the luminosity of line source 21 two end portions, therefore, the distribution of this site 26 in these light guide plate 22 bottom surfaces still is difficult to realize the complete uniformity of whole light guide plate 22 luminous exitances.

Equally, adopt the luminous uniformity coefficient of back lighting device of light guide plate of above-mentioned line of engagement light source also lower.

[summary of the invention]

The defective of non-uniform light the invention provides a kind of light guide plate and back lighting device that adopts line source to have higher luminous uniformity coefficient when adopting line source as light source in order to overcome prior art light guide plate and back lighting device.

The technical scheme that technical solution problem of the present invention is adopted is: a light guide plate is provided, and this light guide plate comprises a first surface, one and this first surface opposing second surface, a plurality of flank side surface and a plurality of diffusion unit.Wherein, this second surface is a light-emitting face, and this diffusion unit is arranged on this first surface, and these a plurality of flank side surface have at least one to be light entrance face, and other flank side surface then is the light mirrored sides.Each diffusion unit is in the projected area of this first surface, is directly proportional with the inverse distance quadratic sum of each coordinate points during the distance of each coordinate points in a plurality of flank side surface of each diffusion unit and this or in outer at least one linear coordinate point set and the linear coordinate points of mirror image that each coordinate points of each diffusion unit and this forms on this light mirrored sides are gathered.

The present invention provides a kind of back lighting device simultaneously, and this back lighting device comprises an at least one line source and an above-mentioned light guide plate.

Compare with prior art, the present invention has the following advantages: it is proportional that intensity is derived at the light of the projected area of this bottom surface and light-emitting face corresponding region in the site of bottom surface of light guide plate of the present invention, can make the light guide plate of line sources such as this cooperations cold cathode fluorescent tube and adopt the back lighting device of this light guide plate luminous even.

[description of drawings]

Fig. 1 is the side view of prior art back lighting device.

Fig. 2 is the network point distribution synoptic diagram of bottom surface of light guide plate shown in Figure 1.

Fig. 3 is the side view of light guide plate first embodiment of the present invention.

Fig. 4 is the network point distribution synoptic diagram of bottom surface of light guide plate shown in Figure 3.

Fig. 5 is linear coordinate point set shown in Figure 4 and the linear coordinate points set of its mirror image in this light guide plate light mirrored sides synoptic diagram.

Fig. 6 is the synoptic diagram that adopts the back lighting device of light guide plate first embodiment of the present invention.

Fig. 7 is the side view of light guide plate second embodiment of the present invention.

Fig. 9 is the side view of light guide plate the 3rd embodiment of the present invention.

[embodiment]

Please consulting Fig. 3 and Fig. 4 together, is the side view of light guide plate first embodiment of the present invention and the network point distribution synoptic diagram of bottom surface.This light guide plate 32 comprises a light entrance face 323, a light-emitting face 321, a plurality of smooth mirrored sides 324, a bottom surface 322 and a plurality of light diffusion site 36 that is distributed in bottom surface 322.Wherein, this light guide plate 32 is rectangular flats, and this light-emitting face 321 and bottom surface 322 are to be oppositely arranged.

This light guide plate 32 is to make with transparent material such as acryl resin, polycarbonate, polyvinyl resin or glass etc.This light entrance face 323 receives from the light source light of (figure does not show), and it is imported in this light guide plate 32.This light-emitting face 321 is derived this light guide plate 32 with light.This light mirrored sides 324 will be incident upon light reflected back light guide plate 32 on it from by these light-emitting face 321 outgoing, cause damage from these light mirrored sides 324 outgoing to prevent light.Light mirrored sides 324 and bottom surface 322 can attach reflecting plate, also can adopt reflectance coating directly to plate thereon, so that the light of transmission fully reflects in light guide plate 32, finally from light-emitting face 321 outgoing.

This site 36 is arranged on these light guide plate 32 bottom surfaces 322, and it is outstanding outside bottom surface 322.This site 36 is the outgoing light homogeneity that are used for improving this light guide plate 32, and it is other light diffusion unit also, as prism structure etc.This site 36 can make by the method for printing or ejection formation.This site 36 is circle spherical surface body, and its projection in light guide plate 32 bottom surfaces 322 is circular, and certainly, this site 36 also can be ellipsoid, polyhedron, cone or the most advanced and sophisticated taper platform etc. of pruning, its in the bottom surface 322 projection also corresponding can be ellipse or polygon.This site 36 presents the ranks distribution of shapes on the bottom surface 322 of this light guide plate 32, wherein, the edge is provided with multiple row site 36 with light entrance face 323 parallel directions (being denoted as Y among the figure) with proportional spacing, and the edge is provided with multirow site 36 with light entrance face 323 vertical directions (being denoted as X among the figure) with proportional spacing.For further strengthening the effect of the 36 pairs of light in site, also can stagger the hemistich distance respectively and present the alternating expression distribution with light entrance face 323 parallel and adjacent odd column and even column sites 36, certainly, this site 36 also can be otherwise regularly arranged.

Seeing also Fig. 5, is linear coordinate point set 37 shown in Figure 4 and the linear coordinate points set of its mirror image in these light guide plate 32 smooth mirrored sides 324 37 ' synoptic diagram.Because this light mirrored sides 324 is minute surfaces, so this linear coordinate point set 37 is a minute surface and form three mirror images linearity coordinate points and gather 37 ' in that light guide plate 32 is outside with three light reflection side 324.Each coordinate points is relevant in the projected area of site 36 on this bottom surface 322 and this light entrance face 323 or in outer at least one linear coordinate point set 37, also with the set 37 of this linear coordinate point in the linear coordinate points of mirror image that on this light mirrored sides 324, forms of each coordinate points gather 37 ' relevant, its physical relationship is: this site 36 on this bottom surface 322 projected area and itself and this a plurality of smooth mirrored sides 324 in or each coordinate points in outer at least one linear coordinate point set 37, and the inverse distance quadratic sum that the linear coordinate points of the mirror image that forms on this light mirrored sides 324 of this each coordinate points is gathered each coordinate points in 37 ' is directly proportional.The radius size R of each site 36 satisfies formula:

$R={\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="C0213991700122.png"\; state="\{\{state\}\}">r</figure-callout>}}_0+k\sqrt{A+B}$

Wherein:

$A=\underset{h=1}{\overset{w-m}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{f}_h{\&Integral;}_0^{L_j}\frac{1}{{(X-(l\cos {\mathrm{\&theta;}}_{\mathrm{hj}}+{\mathrm{xs}}_{\mathrm{hj}}))}^2+{(Y-(l\sin {\mathrm{\&theta;}}_{\mathrm{hj}}+{\mathrm{ys}}_{\mathrm{hj}}))}^2}\mathrm{dl}$

$B=\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{\&Integral;}_0^{L_j}\frac{1}{{(X-(l\cos {\mathrm{\&theta;}}_j+{\mathrm{xs}}_j))}^2+{(Y-(l\sin {\mathrm{\&theta;}}_j+{\mathrm{ys}}_j))}^2}\mathrm{dl}$

(X, Y), (xs _j, ys _j) and (xs _Hj, ys _Hj) belong to a rectangular coordinate system, (X Y) is the coordinate of site 36, (xs _j, ys _j) be the coordinate of corresponding linear coordinate point set 37 initiating terminals, (xs _Hj, ys _Hj) be the coordinate of the linear coordinate points set of the mirror image 37 ' initiating terminal of corresponding linear coordinate point set 37 formation on this light mirrored sides 324, (lcos θ _j+ xs _j, lsin θ _j+ ys _j) be the coordinate of each coordinate points in this rectangular coordinate system in the corresponding linear coordinate point set 37, (lcos θ _Hj+ xs _Hj, lsin θ _Hj+ ys _Hj) be that the linear coordinate points of mirror image that corresponding linear coordinate point set 37 forms on this light mirrored sides 324 is gathered the coordinate of each coordinate points in this rectangular coordinate system in 37 ', w is the summation of light guide plate 32 whole light entrance faces 323 and light mirrored sides 324 numbers, m is the number of light entrance face 323, then the number of light mirrored sides 324 is: w-m, suppose that each light entrance face 323 only has linear coordinate point set 37, for present embodiment, m is 1, w is 4, so the number of light mirrored sides 324 is 3, and L _jBe the length of corresponding linear coordinate point set 37, θ _jBe the angle of cut of set 37 of respective coordinates point and X coordinate axis, θ _HjBe the angle of cut of corresponding linear coordinate point set 37 in linear coordinate points set 37 ' of the mirror image of these light mirrored sides 324 formation and X coordinate axis, f _hBe the reflectivity of corresponding light mirrored sides 324, j is a natural number, and h is an integer, r ₀With k be constant, corresponding to the light guide plate 32 of different structure and size, different linear coordinate point set 37 has different k value and r with the position ₀Value.

When light guide plate 32 of the present invention is used for back lighting device, if bottom surface 322 is not provided with site 36, in it light derive intensity from light entrance face 323 to the light mirrored sides near 324 partly (C districts) far away more weak more from light entrance face 323, light guide plate 32 between light entrance face 323 and the mirrored sides 324 partly (B district) luminous relative C districts a little less than, but, owing to have the edge reflection effect near the light guide plate 32 smooth mirrored sides 324, the actual light line strength in (A district) is bigger away from this light mirrored sides 324 places (B district) intensity than slightly near these light guide plate 32 smooth mirrored sides 324, like this, when the bottom surface 322 in this light guide plate 32 is provided with the site 36 that distributes according to the present invention, since site 36 on this bottom surface 322 projected area and the light of light-emitting face 321 corresponding regions to derive intensity proportional, thereby can realize the whole evenly bright dipping of this light guide plate 32.

Please refer to Fig. 6, is the synoptic diagram that adopts back lighting device one embodiment of light guide plate of the present invention.This back lighting device comprises a light guide plate 32 and is arranged on a line source 31 of its side that as cold cathode fluorescent tube, these light guide plate 32 bottom surfaces 322 are provided with reflecting plate or reflectance coating (figure does not show).Light penetrates from line source 31, enter a part of light in light guide plate 32 backs and on the site 36 of bottom surface 322, carry out scattering and reflection, in the reflecting plate or reflectance coating reflected back light guide plate 32 that the light that is incident upon bottom surface 322 is provided with by this bottom surface 322, thereby can realize the whole uniformly light-emitting of this back lighting device.

Second embodiment of light guide plate of the present invention as shown in Figure 7 and Figure 8.This light guide plate 42 comprises the site 46 on two light entrance faces 423, a light-emitting face 421, light mirrored sides 424, a bottom surface 422 and the bottom surface 422.Wherein, this light guide plate 42 is rectangular flats, and this light-emitting face 421 and bottom surface 422 are to be oppositely arranged.This embodiment and first embodiment are basic identical, and difference is that the light entrance face 423 of second embodiment is two, and certainly, light entrance face 423 also can be more than two.Linear coordinate points set 47 is all arranged near this two light entrance face 423, its number adds up to 6, certainly, also can be other numerical value, and, arranging in the projected area of this bottom surface 422 and depend on this linear coordinate point set 47 numbers and the distance of each coordinate points and this site 46 wherein in this site 46, also depends on light mirrored sides 424 and its number.

When present embodiment light guide plate 42 is used for back lighting device, if site 46 is not set in its bottom surface 422, then in it light to derive intensity partly far away more weak more from light entrance face 423 near 424 from light entrance face 423 to the light mirrored sides, the light guide plate 42 between light entrance face 423 and the light mirrored sides 424 partly luminous relatively a little less than.But, owing to have the edge reflection effect near the light guide plate 42 smooth mirrored sides 424, near these light guide plate 42 smooth mirrored sides 424 actual light line strength is big away from these light mirrored sides 424 place's intensity more slightly, and when the site 46 that distributes according to the present invention is set in these light guide plate 42 bottom surfaces 422, because it is proportional that intensity is derived at the light of the projected area of this bottom surface 422 and light-emitting face 421 corresponding regions in site 46, thereby can realize this light guide plate 42 whole uniformly light-emittings.

Seeing also Fig. 9, is the side view of light guide plate the 3rd embodiment of the present invention.This light guide plate 52 comprises the site 56 on a light entrance face 523, a light-emitting face 521, light mirrored sides 524, a bottom surface 522 and the bottom surface 522.Wherein, this light guide plate 52 is clapboards, and this light-emitting face 521 and bottom surface 522 are to be oppositely arranged, and the projected area of this site 56 on this bottom surface 522 distributes similar with first embodiment of the invention.

Certainly, light guide plate of the present invention can also be other shape, as arc, bending plate etc.; This site also can be arranged at the light-emitting face of light guide plate of the present invention; This site also can recessed this bottom surface; This linear coordinate point set also can be arranged in the light entrance face of this light guide plate.

When above-mentioned light guide plate is used for back lighting device, in the light guide plate flank side surface or outer linear coordinate point set place can place line source, as cold cathode fluorescent tube.

Claims (9)

1. light guide plate, it comprises a first surface, one with this first surface opposing second surface, a plurality of flank side surface and a plurality of diffusion unit, this second surface is a light-emitting face, these a plurality of flank side surface have at least one to be light entrance face, other flank side surface is the light mirrored sides, this diffusion unit is arranged at this first surface, it is characterized in that: each diffusion unit in the projected area of this light guide plate first surface and each diffusion unit and this a plurality of flank side surface or outer at least one linear coordinate point gather in the distance of each coordinate points, and the inverse distance quadratic sum that each linear coordinate point of each diffusion unit and this is integrated into each coordinate points in the linear coordinate points set of the mirror image that forms on this light mirrored sides is directly proportional.

2. light guide plate as claimed in claim 1 is characterized in that: the diffusion unit on this light guide plate first surface protrudes or recessed this first surface.

3. light guide plate as claimed in claim 1 is characterized in that: this diffusion unit is circular in the projection of this light guide plate first surface.

4. light guide plate as claimed in claim 1 is characterized in that: this diffusion unit is ellipse or polygon in the projection of this light guide plate first surface.

5. light guide plate as claimed in claim 1 is characterized in that: these a plurality of diffusion unit shapes are roughly the same.

6. light guide plate as claimed in claim 1 is characterized in that: these a plurality of diffusion units are arranged.

7. light guide plate as claimed in claim 1 is characterized in that: this first surface and these a plurality of diffusion units are one-body molded.

8. light guide plate as claimed in claim 3 is characterized in that: this diffusion unit at the circular radius R of the projection of this first surface is:

$R=r_0+k\sqrt{A+B}$

Wherein:

$A=\underset{h=1}{\overset{w-m}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{f}_h{\&Integral;}_0^{L_j}\frac{1}{{(X-({l\cos \mathrm{\&theta;}}_{\mathrm{hj}}+{\mathrm{xs}}_{\mathrm{hj}}))}^2+{(Y-({l\sin \mathrm{\&theta;}}_{\mathrm{hj}}+{\mathrm{ys}}_{\mathrm{hj}}))}^2}\mathrm{dl}$

$B=\underset{j=1}{\overset{m}{\mathrm{\&Sigma;}}}{\&Integral;}_0^{L_j}\frac{1}{{(X-({l\cos \mathrm{\&theta;}}_j+{\mathrm{xs}}_j))}^2+{(Y-({l\sin \mathrm{\&theta;}}_j+{\mathrm{ys}}_j))}^2}\mathrm{dl}$

(X, Y), (xs _j, ys _j) and (xs _Hj, ys _Hj) belong to a rectangular coordinate system, (X Y) is the coordinate of site, (xs _j, ys _j) be that corresponding linear coordinate is put the coordinate at top together, (xs _Hj, ys _Hj) be that corresponding linear coordinate point is integrated into the linear coordinate points of the mirror image that forms on this light mirrored sides coordinate at top together, (lcos θ _j+ xs _j, lsin θ _j+ ys _j) be the coordinate of each coordinate points in this rectangular coordinate system in the corresponding linear coordinate point set, (lcos θ _Hj+ xs _Hj, lsin θ _Hj+ ys _Hj) be that corresponding linear coordinate point is integrated into the coordinate of each coordinate points in this rectangular coordinate system in the linear coordinate points set of the mirror image that forms on this light mirrored sides, w is the summation of whole light entrance faces of this light guide plate and light mirrored sides number, m is the number of light entrance face, then the number of light mirrored sides is: w-m, L _jBe the length of corresponding linear coordinate point set, θ _jBe the angle of cut of set of respective coordinates point and X coordinate axis, θ _HjBe that corresponding linear coordinate point is integrated into the linear coordinate points set of mirror image of this light mirrored sides formation and the angle of cut of X coordinate axis, f _hBe the reflectivity of corresponding light mirrored sides, j is a natural number, and h is an integer, r ₀With k be constant, corresponding to the light guide plate of different structure and size, the set of different linear coordinate point has different k value and r with the position ₀Value.

9. back lighting device, it comprises an at least one line source and a light guide plate, this line source is arranged on light entrance face one side of this light guide plate, it is characterized in that: this light guide plate is as each described light guide plate of claim 1 to 8.

Images