JP2001307527A - Surface emitting apparatus and backlight-type optical system and display using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light weight light guide plate by appropriately controlling the shape of a slant face and light diffusion pattern index of the light guide plate. SOLUTION: The light guide plate used in the surface emitting apparatus of the invention has a slant face which comprises plural planes. The pattern indexes of the planes are changed continuously. At connections between the patterns, the pattern index of one plane that is closer to a filamentous light source is used as a reference line. The pattern index of the other plane which is far from the filamentous light source and is adjacent to the plane having the reference line pattern index is connected continuously to the reference line pattern index. The light guide plate having such a series of patterns is thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a planar light emitting device used as a display device such as a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, an edge light type planar light emitting device has been used as a light guide plate of a liquid crystal display device, and is disclosed, for example, in Japanese Utility Model Application Laid-Open No. 54-135190. In a planar light emitting device of this type (hereinafter also referred to as a planar light emitting device), a light diffusion pattern is formed on a reflection surface 23 of a light guide plate 17 as shown in FIGS. The linear light source 22 is arranged at 25. Reflective surface 23
There is a case where a reflection sheet (not shown) is brought into close contact with the light guide plate 17 and a surface diffusion sheet or a prism sheet (not shown) is arranged on the light exit surface 24 of the light guide plate 17. To reduce the weight of the planar light-emitting device having this configuration, the thicknesses t1 and t2 of the light guide plate 17 on the light incident end side and the tip end side have been reduced so far.

[0003]

However, the thickness t1 of the light-incident end 25 of the light guide plate 17 facing the linear light source 22.
However, there is a problem in that the outer diameter d1 of the linear light source 22 cannot be made smaller than the diameter of the light source plate, and the thickness t2 of the thin portion at the tip is restricted in the molding process. Light guide plate 1
The slope (reflection surface) 23 of 7 has a very large effect on the luminance distribution of the emitted light. Especially around the reflection surface 23,
Regarding a method of reducing the weight of the light guide plate 17 by forming the light guide plate 17 from a plurality of surfaces, a method of reducing the thicknesses t1 and t2 of the light guide plate 17 has not been established because an appropriate pattern design for equalizing luminance has not been established. Has been followed.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention achieves a reduction in the weight of a light guide plate by appropriately setting the shape of the slope of the light guide plate and the light diffusion pattern ratio. .

That is, the light guide plate used in the planar light emitting device of the present invention has a reflecting surface composed of a plurality of planes, continuously changes the pattern ratio formed on each plane, and connects the patterns. Is a light guide plate composed of a series of patterns continuously connected to a pattern rate far from the linear light source and close to the reference line pattern rate, using a pattern rate closer to the linear light source as a reference line.

A planar light emitting device according to the present invention is a planar light emitting device having a light source and a light guide plate on which a light diffusion pattern is formed, wherein the light guide plate has a reflecting surface composed of a plurality of planes on which a light diffusion pattern is formed. Wherein the area ratio of the light diffusion pattern continuously changes at the boundary between the planes.

In one embodiment, the light diffusing pattern formed on the light diffusing pattern is a light guide plate comprising two flat surfaces, and the light diffusing pattern of the light diffusing pattern forming the light diffusing pattern on the light incident end side. The pattern ratio is formed by extending the light exit surface of the light guide plate portion and the reflection surface on which the light diffusion pattern is formed to the side opposite to the light entrance end, and extending to a portion where the light exit surface or the light exit surface intersects. The method comprises applying the reflection surface pattern ratio of the reflection surface portion of the light guide plate close to the light incident end of the light diffusion pattern ratio obtained with the luminance uniformity.

[0008] In one embodiment, the light diffusing surface of the light guide plate portion is a light guide plate having a light diffusing pattern formed of two surfaces and the light diffusing pattern of the light diffusing pattern on the side opposite to the light incident end. The pattern ratio is the inverse of the light diffusion pattern ratio of the light guide plate having a shape in which the light emitting surface of the light guide plate portion and the reflection surface on which the light diffusion pattern is formed are extended to the light incident end side. It consists of applying the reflection surface pattern ratio of the reflection surface portion near the light incident end.

In one embodiment, the pattern ratio according to the second aspect is continuously connected to the pattern ratio according to the third aspect over both sides of the boundary between the planes. It is characterized by.

In one embodiment, a light guide plate in which a reflection surface on which a light diffusion pattern is formed is composed of three or more planes,
According to the second aspect and the third aspect, the light diffusion pattern ratio of the reflection surface is used.

[0011] A backlight optical system or a display device according to the present invention has the above-mentioned planar light emitting device.

The operation of the present invention is as follows.

[0013] The light guide plate has a slope composed of a plurality of planes,
The pattern rate formed on each plane is continuously changed, and the connection between these patterns is set to the pattern rate closer to the linear light source as the reference line, far from the linear light source and close to the reference line pattern rate. It is composed of a series of patterns connected continuously to the pattern rate. Therefore, by appropriately setting the shape of the slope of the light guide plate and the light diffusion pattern ratio, the weight of the light guide plate can be reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows an embodiment of a planar light emitting device according to the present invention, in which a reflecting surface 4 of a light guide plate 1 has two flat surfaces 4.
1, 42. Each plane 41 of the light guide plate 1,
42 is provided with a reflection pattern. The linear light source 2 is arranged close to the light incident end face 15 of the light guide plate 1. In order to reduce the light loss of the linear light source 2, a reflector 3 is arranged around the linear light source 2 to prevent light leakage to the surroundings.

A reflection sheet 6 is arranged on the lower surface of the light guide plate 1 along the reflection surface 4 as necessary. A diffusion sheet or a prism sheet 9 is disposed on the light-emitting surface of the light guide plate 1, and a liquid crystal panel 7 is disposed on the sheet 9. Parts including the light guide plate 1 are housed in the housing 5.

Next, the light diffusion pattern formed on the reflection surface 4 will be briefly described.

FIG. 28 is a plan view of a conventional light guide plate 17, FIG. 29 is a plan view of a light diffusion pattern 26 formed on the reflection surface 4, and FIG.

The light diffusion pattern 26 has a function of causing light incident from the light incident end 25 of the light guide plate 17 to exit from the light exit surface 24, and emits light using the area ratio (light diffusion pattern ratio) of the light diffusion pattern 26. Determine the percentage.

The shape of the light diffusion pattern 26 is generally a round shape as shown in FIG. 29, and other shapes such as a square shape can also be adopted. As shown in FIG. 29, the light incident end 25 of the light guide plate 17
The shape of the light diffusion pattern 26 becomes larger as the distance from the light diffusion pattern 26 increases. It is possible to equalize the luminance distribution of light emitted from the light exit surface 24 of the light guide plate 17 having a wedge-shaped cross section by a conventional method.

Hereinafter, the structure of the light guide plate used in the present invention will be described in detail.

The light guide plate 1 shown in FIG. 3 is a light guide plate developed to achieve the weight reduction of the present invention.

The light guide plate 1 has a slope on which a reflection pattern is formed.
It is constituted by a reflection surface 4 composed of two planes 41 and 42. The two planes 41 and 42 are bent so as to be depressed inward in a side view. The intersection point o of the two planes 41 and 42 will be referred to as an inflection point. Next, as shown in FIG. 4, an intersection with the light incident end face 15 on the extension of the plane 42 is denoted by f, and an intersection with the end face 11 (cd) on the extension of the plane 41 is denoted by e. A light guide plate D having a section afcd shown in FIG.
11. A light guide plate having the basic shape of the light guide plate D12 having the cross section abed shown in FIG. 6 is drawn. That is, the light guide plate D
The light guide plate 1 shown in FIG. 3 is a combination of the right portion D1 of the inflection point O of FIG. 11 and the left portion D2 of the inflection point O of the light guide plate D12.
It is.

Next, FIG. 7 shows the design value of the light guide plate D11 and the light diffusion pattern ratio for equalizing the luminance characteristics thereof, and FIG. 7 shows the light guide plate D12 and the light diffusion pattern ratio for equalizing the luminance characteristics thereof. FIG. 8 shows the design values of.

The slope angle θ1 of the light guide plate D11 is equal to the light guide plate D12.
Since it is smaller than the slope angle θ2, the reflection diffusion efficiency of the reflection surface 4 due to the light diffusion pattern is reduced. Therefore, the light diffusion pattern ratio curve Ll of the light guide plate D11 shown in FIG. 7 is higher than the light diffusion pattern ratio curve L2 of the light guide plate D12 shown in FIG. 8, and the pattern at the thin end portion of the light guide plate. The rate curve rises.

The reflection and diffusion effect of the light diffusion pattern is slightly different depending on the pattern forming method, the printing method, the forming method using an etching die, and the individual pattern surface properties. Will be needed.

The present inventors have determined that each pattern has 3 to
By experimentally producing four types of light guide plates having different slope angles, the light diffusion pattern ratio of the light guide plate having a new slope angle is designed to be predicted.

FIG. 9 shows the light guide plate D11.
A light guide plate D corresponding to the right side of the inflection point O of the light guide plate shown in FIG.
l. A part a2-K of the pattern curve L1 corresponding to the right side portion D1 of the light guide plate in the light diffusion pattern rate characteristic of FIG.
2 is shown in FIG.

FIG. 11 shows the light guide plate D12. In this figure, the hatched portion is the light guide plate D2 corresponding to the left side of the inflection point O of the light guide plate of the present invention shown in FIG. FIG. 12 shows a part b1-K1 of the pattern curve L2 corresponding to the left portion D2 of the light guide plate in the light diffusion pattern ratio characteristic of FIG.

FIG. 13 shows the right side D1 of the light guide plate of FIG. 9 and FIG.
The light source device of the present invention is a united view of the left side portion D2 of the light guide plate described above, which is integrally formed.

FIG. 14 shows a part a2-K2 of the pattern curve L1 of FIG. 10 and a part b1-K2 of the pattern curve L2 of FIG.
K1 is described.

As described above, the pattern curve of the left portion D2 of the light guide plate is designed to be lower than the pattern curve of the right portion D1 of the light guide plate due to the effect of the reflection and diffusion efficiency due to the difference in the slope angle, and the pattern curve L2 Is located below the end point K2 of the pattern curve Ll. Therefore, the end points K1 and K2 of both patterns cannot be continuously connected.

FIG. 18 shows a method of continuously connecting the pattern curve L1 from the end point k2 of the pattern curve L1 to the pattern curve L2 with the pattern curve L1 as a base line.

FIG. 19 shows the luminance characteristics at this time. The brightness rises from the vicinity of the connected K4 and the K corresponding to the inflection point portion
It reaches the peak at around 2, and then descends gently, and at the thin end portion, it is lower than the light entry end luminance. This is due to the formation of the peak of the brightness increase having the peak at K2.

FIG. 17 shows a method of continuously connecting a pattern curve L2 from an end point k1 of the pattern curve L2 with the pattern curve L2 as a base line. A light guide plate having a stable luminance uniformity can be obtained by the present connection pattern ratio curve.

In FIG. 20, a part of the light from the linear light source 2 is totally reflected directly on the light exit surface 8 as shown by the optical path h1 and on the reflection surface 4 as shown by the optical path h2. The light exit surface 8 of the light guide plate 1 is diffusely reflected by the diffusion pattern 16 near O.
It is emitted from a part of. The effect of being reflected and diffused by the light diffusion pattern near the inflection point on the reflection surface 41 is higher than the effect of being reflected and diffused by the light diffusion pattern near the inflection point of the reflection surface 42. Therefore, in the method of continuously connecting the end point of the pattern curve L1 to the pattern curve L2 with the pattern curve L1 of FIG. 18 as a base line, the diffusion pattern rate is increased from before and after the inflection point,
In order to increase the output light amount, the luminance increases as shown in FIG. 19, and the luminance uniformity decreases. From the above, the formation of the diffusion pattern rate of the reflecting surface 4 consisting of the continuous connection of the pattern curve L2 from the end point of the pattern curve L2 with the pattern curve L2 of FIG. A light plate will be obtained.

(Second Embodiment) FIG. 2 shows an example of the invention in which the inflection point o1 is located closer to the light incident end. In this embodiment, the effect of reducing the weight is higher than that of the light guide plate shown in FIG.

The contents of the present invention will be described with reference to FIGS. FIG. 21 shows an example of the second invention again. FIG.
In FIG. 21, two light guide plates are created based on FIG.

In FIG. 22, the point intersecting the extension of the slope b2-o2 is designated by e2 (in the example of the first invention, the non-light incident end c2-d).
Although there was an intersection on the light exit surface a1-d1 in this example, it intersects on the light exit surface a1-d1, see FIG. 2). Light guide plates a2, b2, e2 shown in FIG.
2, f2, c2, and d2 are created. The light guide part corresponding to the left side of the inflection point o2 in the light guide plate shown in FIG. 21 is a hatched part D21 shown in FIG. 23, and the light guide part corresponding to the right side of the inflection point o2 in the light guide plate shown in FIG. A hatched portion D22 shown in FIG. A light diffusion pattern is designed for each of the light guide plates, and a series of design methods are performed in exactly the same manner as in FIGS. 9 to 17 described in the example of the first invention. However, in this case, the angle difference between the angles θ1 and θ2 of the reflecting surface 4 shown in FIGS.
24 is higher than the brightness level of FIG. 24, the brightness level of the left portion D21 of FIG.
The light diffusivity is designed to lower the level.

FIG. 25 is a sectional view of a light guide plate including three reflection planes. As shown in FIG. 4, each light guide plate was set to a light guide plate formed on an extension of the light guide plate.
26, the pattern ratio characteristics of the light guide plates extended from the light guide plate portions D1, D22, and D23 are equalized in luminance and the diffusion pattern ratio of the corresponding portion is set as L1 in FIG.
It is each diffusion pattern rate curve of L1, L12, and L13.

In order to connect these characteristic curves as a series of continuous diffusion pattern ratio curves, as shown in FIG. 27, a pattern ratio curve L11 corresponding to the light guide plate portion D21 is connected to L12 as a base line, and L12 is connected as a base line. Connect to L13. According to the above method, it is possible to design the reflection surface luminance diffusion pattern ratio necessary for equalizing the luminance of the light guide plate including not only two planes but also three or more reflection surfaces 4.

[0042]

The light guide plate of the present invention is formed by a plurality of reflection surfaces so that the reflection surface is refracted inward, thereby realizing more effective weight reduction. By applying a light reflection pattern consisting of a series of continuous pattern rate curves formed by the above, the stability of luminance uniformity can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of the light source device of the present invention, in which a light guide plate has two reflecting surfaces formed of a light guide plate.

FIG. 2 is a diagram showing an example of the light source device of the present invention in which the position of an inflection point is different from that in FIG. 1;

FIG. 3 is a basic view of the light guide plate of the first invention.

FIG. 4 is an explanatory diagram for separating the light guide plate shown in FIG. 3 into two light guide plates.

FIG. 5 is a cross-sectional view of the light guide plate separated from the view shown in FIG.

FIG. 6 is a cross-sectional view of the light guide plate separated from the view shown in FIG.

7 is a diagram illustrating a wedge-shaped light guide plate of FIG. 5 and a light diffusion pattern ratio thereof.

FIG. 8 is a diagram illustrating the wedge-shaped light guide plate of FIG. 6 and its light diffusion pattern ratio.

FIG. 9 is a diagram illustrating the light guide plate of FIG. 7 and a light guide extraction portion corresponding to the present invention in the light guide plate.

10 is a diagram illustrating the light diffusion pattern ratio of the light guide plate corresponding to the characteristic portion of the present invention based on the light diffusion pattern ratio of FIG.

FIG. 11 is a diagram illustrating the light guide plate of FIG. 8 and a light guide plate portion corresponding to a feature of the present invention.

12 is a diagram for explaining the light diffusion pattern ratio of the light guide plate portion corresponding to the characteristic portion of the present invention based on the light diffusion pattern ratio of FIG.

FIG. 13 is a diagram illustrating a configuration of the light guide plate and a method of synthesizing the respective light diffusion pattern rates.

FIG. 14 is a diagram illustrating a configuration of a light guide plate and a method of synthesizing a light diffusion pattern ratio of each light guide plate.

FIG. 15 is a diagram for explaining a method of continuously connecting the light diffusion pattern rates of the light guide plate.

FIG. 16 is a diagram illustrating a method of connecting the light diffusion pattern rates of the light guide plate continuously.

FIG. 17 is a diagram for explaining a method of continuously connecting the light diffusion pattern rates of the light guide plate.

FIG. 18 is a diagram illustrating an inappropriate continuous connection method and a luminance characteristic at that time.

FIG. 19 is a diagram illustrating an inappropriate continuous connection method and a luminance characteristic at that time.

FIG. 20 is a diagram illustrating light diffusion characteristics of a light guide plate.

FIG. 21 is a diagram illustrating an example of the invention in which the inflection point is located at a position closer to the light incident end.

FIG. 22 is a diagram showing an example of the invention in which the inflection point is located at a position closer to the light incident end.

FIG. 23 is a diagram showing an example of the invention in which the inflection point is located at a position closer to the light incident end.

FIG. 24 is a diagram showing an example of the invention in which the inflection point is located at a position closer to the light incident end.

FIG. 25 is a cross-sectional view illustrating an example of the invention of a light guide plate including three reflection surfaces.

26 is a diagram illustrating an example of the invention of the light guide plate including the three reflection surfaces illustrated in FIG. 25 and a method of designing a light diffusion pattern ratio thereof.

27 is a diagram illustrating an example of the invention of the light guide plate including the three reflection surfaces illustrated in FIG. 25 and a method of designing a light diffusion pattern ratio thereof.

FIG. 28 is a diagram illustrating a conventional fusuma-shaped light guide plate.

FIG. 29 is a diagram illustrating a conventional fusuma-shaped light guide plate.

FIG. 30 is a diagram showing a light diffusion pattern ratio of a conventional fusuma-type light guide plate.

FIG. 31 is a diagram illustrating a conventional fusuma-shaped light guide plate.

FIG. 32 is a view illustrating a conventional fusuma type light guide plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-guide plate 2 Linear light source 3 Reflector 4 Reflection surface 5 Case 6 Reflection sheet 7 Liquid crystal panel 15 Light entrance end surface 41, 42 Plan

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Claims (7)

[Claims] 1. A planar light emitting device having a light source and a light guide plate having a light diffusion pattern formed thereon, wherein the light guide plate has a reflecting surface composed of a plurality of flat surfaces having a light diffusion pattern formed thereon.
A planar light emitting device wherein the area ratio of the light diffusion pattern continuously changes at the boundary between the planes. 2. The planar light emitting device according to claim 1, wherein the reflection surface on which the light diffusion pattern is formed is a light guide plate having two planes, and the reflection surface on which the light diffusion pattern on the light incident end side is formed. The light diffusion pattern ratio of the light guide plate portion to be formed is such that the light exit surface of the light guide plate portion and the reflection surface on which the light diffusion pattern is formed are extended to the opposite to the light entrance end side, and the portion where the light entrance surface or the light exit surface intersects. A planar light emitting device comprising applying a reflection surface pattern ratio of a reflection surface portion close to a light entrance end of a light diffusion pattern ratio obtained with luminance uniformity of a light guide plate formed so as to extend up to the light guide plate. 3. The planar light emitting device according to claim 1, wherein the light diffusing pattern is formed on a light guide plate having two light reflecting surfaces, and the light diffusing pattern is formed on the opposite light incident end side. The light diffusion pattern ratio of the light guide plate portion to be obtained is the brightness uniformity of the light guide plate formed by extending the light exit surface of the light guide plate portion and the reflection surface on which the light diffusion pattern is formed to the light incident end side. A planar light-emitting device comprising applying a reflection surface pattern ratio of a reflection surface portion close to a non-light incident end of a light diffusion pattern ratio. 4. The planar light emitting device according to claim 1, wherein the pattern ratio according to claim 2 is set as a base line across both sides of the boundary between the planes. A planar light emitting device characterized by being continuously connected to a pattern ratio. 5. The surface light emitting device according to claim 1, wherein the reflection surface on which the light diffusion pattern is formed is a light guide plate composed of three or more flat surfaces. A planar light emitting device comprising a diffusion pattern ratio. 6. A backlight optical system having the planar light emitting device according to claim 1. 7. A display device having the planar light emitting device according to claim 1. Description: