JP2003035825A - Light guide plate and planar illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To project light from a light source with equal energy at an arbitrary distance corresponding to a ridge and to thus obtain light projection light which has no luminance spot almost vertically as projection light from a final planar illuminator. SOLUTION: A light guide plate 1 has an incident part P on which the light from the light source is made incident at the center position P1 or one end part position P2 of at least one side face part 4 and projected or recessed ridges 51, 61, 52, and 62 are formed at the top surface part 5 and reverse-surface part 5 concentrically with those positions. A light polarizing sheet 10 in an arcuate prism shape having projecting or recessed ridges 10a and 10b symmetrically with the ridges 51, 61, 52, and 62 of the light guide plate 1 is arranged on the light guide plate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar illuminating device using a light guide plate used in a liquid crystal display device and the like and a light polarizing sheet having the same shape as the light guide plate. The present invention relates to a light guide plate and a flat lighting device that can obtain no emitted light.

[0002]

2. Description of the Related Art A conventional light guide plate guides incident light from a light source such as a point light source through an incident surface of a side surface and emits the light to a front surface and a back surface of the light guide plate. This type of light guide plate has a configuration in which a plurality of point light sources such as LEDs are provided on the side surface of the light guide plate in order to allow incident light to enter the entire area of the light guide plate and obtain desired bright emitted light.

As a conventional light guide plate, a convex or concave shape is randomly provided on the front surface or the back surface of the light guide plate by prisms or blasts, and the incident light incident from the light source is reflected or refracted. It is known that light is emitted from the front surface portion or the back surface portion of the light guide plate while being condensed and condensed.

Further, there is also known a method of diffusing or condensing light emitted from the light guide plate by using a single row-shaped prism sheet or the like on the light guide plate.

When an LED is arranged on the side surface of the light guide plate, since the LED is a point light source, the brightness in the straight direction of the LED is strong and the brightness in the left and right directions is weak. There is known a method in which a light beam from the LED is diffused and spread in the left-right direction.

[0006]

As described above, in the conventional light guide plate, it is necessary to dispose a plurality of point light sources such as LEDs on the side surface, and when the light guide plate is adopted as an illuminating device in a display device of a portable device, the device is used. Since the size of the battery cannot be reduced as a whole, the required current is large, and the battery is consumed quickly, the frequency of battery replacement is increased and there is a problem in economical efficiency.

Further, when the light source is a point light source, the incident light entering the light guide plate propagates concentrically from the center of the point light source. The energy emitted from the front and back surfaces of the light guide plate is not evenly distributed, and convex or concave shapes are randomly provided by prisms or blasts on the front and back surfaces of the light guide plate, and the light is incident from the light source. Even if the incident light is reflected, refracted, condensed, or the like, there is a problem that spots and brightness are reduced as emitted light.

Further, when a single row of prism sheets or the like is used on the upper part of the light guide plate in order to diffuse or condense the light emitted from the light guide plate, it becomes like a point light source. Since the propagation of light is radial, there is a place where the correlation between the light emitted from the light guide plate and the prism sheet does not completely match. As a result, there is a problem in that brightness and the like are generated in the light emitted from the final flat illumination device, and unevenness in brightness occurs on the emission surface.

Further, when a large number of LEDs are arranged side by side, the light rays of adjacent LEDs overlap each other, which causes a brightness difference on the emission surface, which causes a problem in the brightness distribution.

The present invention has been made to solve the above problems, and the incident portion of the light guide plate is set to the center position or one end position of at least one side surface portion, and the convex or concave shape is concentric with these positions. Is provided on the front surface or the back surface of the light guide plate, and is equipped with a light-polarizing sheet having an arc-shaped prism shape having a symmetrical positional relationship with the ridge of the light guide plate. It is an object of the present invention to provide a light guide plate and a planar illumination device that allow the same energy to be emitted and the final emitted light from the planar illumination device to be bright emission light without luminance spots in a substantially vertical direction.

[0011]

In order to solve the above-mentioned problems, a light guide plate according to a first aspect of the present invention is configured such that the incident portion is located at the center position of at least one side surface portion and the front surface portion and / or the back surface portion is concentric with the center position. Is characterized by having convex or / and concave ridges, and the light energy is equally emitted from the light source at an arbitrary distance corresponding to the ridge.

In the light guide plate according to the first aspect, the incident portion is located at the center position of at least one side surface portion, and the front surface portion and / or the back surface portion has a convex or / and concave edge concentric with the central position. Since the light energy is equally emitted from the light source at an arbitrary distance corresponding to the ridge, it can be emitted with uniform brightness anywhere on the front surface or the back surface of the light guide plate.

According to a second aspect of the present invention, in the light guide plate, the incident portion is at least at one end position of the side surface portion, and a convex or / and concave ridge is formed on the front surface portion and / or the rear surface portion concentrically with the end portion position. The light energy is equally emitted from the light source at an arbitrary distance corresponding to the ridge.

According to a second aspect of the present invention, in the light guide plate, the incident portion is at least at one end of the side surface portion and the surface portion or /
And the back surface has a convex or / and concave ridge concentric with the end position, and the light energy is emitted equally from the light source at an arbitrary distance corresponding to the ridge. It is possible to emit light with uniform brightness anywhere in the light source, and even if the light source is a rectangle having a certain size, the incident portion has a maximum spread of 90 degrees, so that the radiation angle of the light source can be allowed.

Further, the light guide plate according to claim 3 is characterized in that the cross section in the direction perpendicular to the normal line of the ridge at the center position or at the one end position and the concentricity is always triangular.

In the light guide plate according to the third aspect, since the cross section in the direction perpendicular to the normal to the ridge at the center position or the one end position and the concentric direction is always triangular, the emission angle from the front surface portion or the back surface portion is substantially the same. It is possible to obtain the same outgoing light.

A light guide plate according to a fourth aspect is characterized in that the ridges are continuous or discontinuous.

In the light guide plate according to the fourth aspect, since the ridge is continuous or discontinuous, not only the emitted light can be emitted from the front surface portion or the back surface portion along the ridge, but also at the target position. It can also be partially emitted.

Further, the light guide plate according to claim 5 is characterized in that the angle of the triangular ridge is in the range of 80 to 179 degrees.

In the light guide plate according to the fifth aspect, since the angle of the triangular ridge is in the range of 80 degrees to 179 degrees, the interval between the ridges is adjusted according to the change in the angle of the ridge in the light guide plate. In addition, the pitch between the ridges can be set shorter as the distance from the light source increases, and the height or depth of the convex or concave ridge can be set.

Further, the light guide plate according to claim 6 is characterized in that the angle formed by the triangular shape with the virtual horizontal plane of the front surface portion and / or the rear surface portion is in the range of 0.01 to 10 degrees.

In the light guide plate according to the sixth aspect, the angle between the triangular shape and the virtual horizontal plane of the front surface portion and / or the rear surface portion is 0.
Since it is in the range of 01 degree to 10 degrees, it is possible to adjust the interval between the edges by changing the angle formed with the virtual horizontal plane, and to set the pitch between the edges shorter as the distance from the light source increases. The height or depth of a convex or concave ridge can be set.

Further, a light guide plate according to a seventh aspect is characterized in that a triangular ridge portion is flatly cut out.

In the light guide plate according to the seventh aspect, since the triangular ridge portion is flatly cut, for example, the flat ridge portion is provided only on the front surface portion, and the reflector is provided near the back surface portion. In this case, the light totally reflected on the front surface proceeds in the direction of the back surface and goes out from the back surface to the outside. Although the light is reflected or refracted, the flat portion in the present invention can be emitted from the surface portion substantially straight.

Further, the light guide plate according to claim 8 is characterized in that adjacent surfaces of the triangular ridges are curved or arcuate.

In the light guide plate according to the eighth aspect, since the adjoining surfaces of the triangular ridges are curved or arcuate, the light is diffused when the curved or arcuate ridges are indented. Also, in the case of a curved or arcuate ridge surface that bulges outward, the emission angle of the emitted light should be adjusted so that the light is condensed at a location that matches the curvature and the light is diffused further away. It can be changed.

Further, the flat illumination device according to claim 9 is
A light source, a light guide plate having a central position of at least one side face as an incident part, and a convex or / and concave ridge concentric with the central position on the front face or / and the back face, and a position corresponding to the ridge And a light-polarizing sheet having an arc-shaped prism shape in relation to each other, and the light emitted from the light guide plate with equal light energy from the light source at an arbitrary distance corresponding to the ridge is front surface portion and / or back surface portion by the light polarizing sheet. It is characterized in that the light is emitted in a direction substantially at a right angle.

A flat illumination device according to claim 9 includes a light source,
A light guide plate having a convex portion and / or a concave ridge concentric with the central position on the front surface portion and / or the rear surface portion as the incident portion at the center position of at least one side surface portion, and a circle having a positional relationship corresponding to the ridge. A light-polarizing sheet having an arc-shaped prism is provided, and light emitted from the light guide plate has equal light energy at an arbitrary distance corresponding to a ridge from the light source, and the light emitted from the light guide plate is substantially directed to the front surface portion and / or the back surface portion. Since the light is emitted in a right angle direction, the emitted light can be obtained from the entire front surface with respect to the observation side.

A flat lighting device according to a tenth aspect of the present invention is
The light source and at least one end portion of the side surface is the incident portion,
A light guide plate having a convex or / and concave ridge concentric with an end position on a front surface portion and / or a back surface portion, and a light polarizing sheet having an arc-shaped prism shape in a positional relationship corresponding to the ridge. The light emitted from the light guide plate having the same light energy at an arbitrary distance corresponding to the ridge from the light source is emitted in a direction substantially perpendicular to the front surface portion and / or the back surface portion by the light polarizing sheet.

According to a tenth aspect of the present invention, there is provided a planar illumination device in which a light source and at least one end portion of a side surface is an incident portion, and a convex or / and concave ridge is concentric with the end portion on a front surface portion and / or a back surface portion. And a light-polarizing sheet having an arc-shaped prism shape in a positional relationship corresponding to the ridge, and the light energy is equal and emitted from the light guide plate at an arbitrary distance corresponding to the ridge from the light source. Since the light is emitted by the light polarizing sheet in a direction substantially perpendicular to the front surface portion and / or the back surface portion, emitted light can be obtained from the entire front surface on the observation side.

Further, in the flat illumination device according to the eleventh aspect of the invention, the light polarizing sheet is provided with a convex shape or // corresponding to a center position from a center position of a side surface of the light guide plate and a position concentric with a ridge of the light guide plate.
And having a concave ridge.

In the flat illumination device according to the eleventh aspect, the light polarizing sheet has convex or / and concave ridges corresponding to the center position of the side surface of the light guide plate and the position concentric with the ridge of the light guide plate. Therefore, the light emitted from the convex or concave ridge of the light guide plate can be completely guided to the convex or concave ridge of the present light polarizing sheet at the shortest distance.

A flat lighting device according to a twelfth aspect of the present invention is
The light polarizing sheet is characterized by having a convex or / and concave ridge corresponding to an end position from the end of the light guide plate and a position concentric with the ridge of the light guide plate.

In the flat illumination device according to the twelfth aspect of the invention, the light polarizing sheet has the convex or / and concave ridges corresponding to the end position of the light guide plate and the position concentric with the ridge of the light guide plate. Light emitted from the convex or concave ridge of the light guide plate can be completely guided to the convex or concave ridge of the present light polarizing sheet at the shortest distance.

Further, in the flat illumination device according to the thirteenth aspect, the ridge of the light polarization sheet is always triangular in cross section in a direction perpendicular to the normal to the ridge corresponding to the center position or the end position. It is characterized by being.

In the flat illumination device according to the thirteenth aspect, the cross section in the direction perpendicular to the normal line to the ridge corresponding to the ridge of the light polarizing sheet at the center position or the position concentric with the end position is always triangular. The light emitted from the light guide plate can be polarized.

Further, the flat illumination device according to claim 14 is
The light polarizing sheet is continuous or discontinuous.

In the flat illumination device according to the fourteenth aspect, since the light polarizing sheet is continuous or discontinuous, it is possible to selectively polarize the portion that needs to be polarized with respect to the light emitted from the light guide plate.

Further, in the flat illumination device according to the fifteenth aspect, the angle of the triangular ridge of the light polarizing sheet is 60 degrees to 80 degrees.
It is characterized by being in the range of degrees.

In the flat illumination device according to the fifteenth aspect, since the angles of the triangular edges of the light polarizing sheet are in the range of 60 to 80 degrees, the pitch between the edges and the height of the edges are adjusted according to the purpose. Or you can set the depth.

A flat lighting device according to a sixteenth aspect of the present invention is
The angle formed by the triangular shape of the light polarizing sheet with the virtual horizontal plane of the light polarizing sheet is in the range of 20 degrees to 60 degrees.

According to the sixteenth aspect of the present invention, in the flat illuminating device, the angle between the triangular shape of the light polarizing sheet and the virtual horizontal plane of the light polarizing sheet is in the range of 20 to 60 degrees. Can be controlled.

Further, in the flat illumination device according to the seventeenth aspect, the light source and the position of the center or the end of at least one side surface is the incident part, and the center or the end position is on the front surface and / or the back surface. A light guide plate having concentric convex and / or concave ridges; and a light polarizing sheet having convex and / or concave ridges that are equal to the ridges of the light guide plate so as to face the ridges. The ridge angle and the ridge angle of the light polarizing sheet are always the same.

According to a seventeenth aspect of the present invention, in a flat illumination device, a light source and a center or an end of at least one side face is an incident part, and a front face and / or a back face is concentric with the center position or the end position. A light guide plate having a convex or / and concave ridge and a light polarizing sheet having a convex or / and concave ridge equal to the ridge of the light guide plate so as to face the ridge, Since the angle and the angle of the edge of the light polarizing sheet are always the same, it is possible to make the angle of the light beam before exiting from the edge of the light guide plate equal to the angle of the light ray after entering the edge of the light polarizing sheet. In addition, the light emitted from the ridge of the light guide plate can be guided to the ridge of the light polarizing sheet completely at the shortest distance and the light can be efficiently polarized.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Incidentally, the present invention, the incident portion of the light guide plate is located at the center or one end of at least one side surface portion,
Convex shape with the apex angle of 80 degrees to 179 degrees concentric with the position of these incident parts on the front surface and the back surface and the angle between the virtual horizontal plane of the front surface and the back surface within the range of 0.01 to 10 degrees. And ridges with a concave triangular cross section are provided continuously or discontinuously so that the light energy is emitted equally from the light source at an arbitrary distance corresponding to the ridge, and the light is polarized in the shape and symmetry provided on the light guide plate. A light guide plate and a flat lighting device are provided in which a light polarizing sheet is disposed above a light guide plate to polarize light emitted from the light guide plate in a substantially vertical direction to obtain uniform and bright light emitted from the flat lighting device without uneven brightness. It is provided.

1 and 2 are plan views showing an embodiment of a light guide plate according to the present invention. 1 is a plan view of the light guide plate when the light source is arranged at the center position of the side surface portion of the light guide plate, and FIG. 2 is a plan view when the light source is arranged at one end position of the side surface portion of the light guide plate. It is a top view of a light board. FIG. 3 shows FIG.
Point P1 of the light guide plate and P1-A connecting the normal line of the concentric ridge from the point P1 to the perpendicular direction A, and the point P2 of the light guide plate shown in FIG. It is sectional drawing of P2-B which connects with the direction B. FIG. 4 is a partially enlarged cross-sectional view of the light guide plate of FIG. 3, showing a ray trajectory, FIG.
(B), FIG. 6 and FIG. 7 are partially enlarged views showing another configuration example of the ridge provided in the light guide plate according to the present invention.

The light guide plate 1 is formed of transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7 into a substantially rectangular shape. In the light guide plate 1, the incident portion P is the center position P1 of at least one side surface portion (side surface portion 4 in the example of FIG. 1) of the side surface portions 4, 7, 8 and 9. Further, as shown in FIG. 3, the light guide plate 1 has convex ridges 51 and 61 and concave ridges 52 and 62 on the front surface portion 5 and / or the rear surface portion 6 concentrically with the center position P1.

Explaining further, the convex ridges 51 and 61 in FIG. 3 are radiating like a line S1 so as to draw concentrically around the center position P1 point of the one side surface portion 4 of the front surface portion 5 and the back surface portion 6. And the concave ridges 52 and ridges 62 in FIG. 3 are provided radially as shown by the line S2.

Here, the convex ridges 51 and 61 are defined as the lines S1 and S3 (odd numbers), and the concave ridges 52 and 62 are defined as the lines S2 and S4 (even numbers). Line Sn) is shown. In addition, although not shown, convex ridges 51 and ridges 61 are provided intermittently to form a flat surface between the convex ridges 51 and ridges 61, and concave ridges 52 and ridges 62 are provided intermittently to form a convex shape. It is also possible to make a plane between the ridges 51 and 62.

Further, as shown in FIG. 2, as another structure of the light guide plate 1, the incident part P is at least one of the side surface parts 4, 7, 8 and 9 (the side surface part 4 in the example of FIG. 2). It can also be set to one end position P2 at the corner of the. In this case, as shown in FIG. 3, on the front surface portion 5 and / or the back surface portion 6, convex ridges 51 and 61 and concave ridges 52, which are concentric with the one end position P2, are provided.
It has 62.

To explain further, the convex ridges 51 and 61 in FIG. 3 are drawn like the line S1 so as to be concentric about the one end portion position P2 point of the one side surface portion 4 of the front surface portion 5 and the back surface portion 6. The ridges 52 and the ridges 62 having a concave shape in FIG. 3 are provided radially as well as the lines S2.

Here, the convex ridges 51 and 61 are defined as lines S1 and S3 (odd number), and the concave ridges 52 and 62 are defined as lines S2 and S4 (even number), and the convex and concave shapes are continuous (line Sn). ) Shows. In addition, although not shown, convex ridges 51 and ridges 61 are provided intermittently to form a flat surface between the convex ridges 51 and ridges 61, and concave ridges 52 and ridges 62 are provided intermittently to form a convex shape. It is also possible to make a plane between the ridge 51 and the concave ridge 62.

With the above configuration, the light rays that have entered the ridge 51, the ridge 61, the ridge 52, and the ridge 62 from the light source 2 are at the same distance from the light source 2 that is the emitted and emitted light. At this time, the light energy is emitted equally.

Although the description is duplicated here, in FIG. 3, the central position P1 of at least one side surface portion (side surface portion 4 in the example of FIG. 3) of the side surface portions 4, 7, 8 and 9 in FIG. Department P
And shows a cross section of a line P1-A that connects the center position P1 of the incident portion P and the normal line of the concentric ridge and the perpendicular direction A,
At least one end position P2 of the side surface portions 4, 7, 8 and 9 in FIG. 2 is defined as the incident portion P, and a line connecting the end position P2 of the incident portion P and the normal line of the ridge concentric with the perpendicular direction B. P2-B
The cross section of FIG.

The front surface portion 5 and the back surface portion 6 are radiated from the incident portion P.
The convex ridges 51 and the ridges 61 and the concave ridges 52 and the ridges 62 provided in the section have a triangular cross section. And the convex ridge 5
The angle θ1 of 1 is in the range of 80 degrees to 179 degrees, and the concave ridge 52
The angle θ2 is set in the range of 80 degrees to 179 degrees. Further, the angle θ3 formed between the virtual horizontal plane 1c of the front surface portion 5 and the virtual horizontal plane 1d of the rear surface portion 6 is set in the range of 0.01 degrees to 10 degrees.

As described above, each angle θ1, θ2 and θ3
By setting, as shown in FIG. 4, when a light ray is incident on the light guide plate 1 from the center position P1 or the end position P2 of the incident portion P, the light ray incident on the light guide plate 1 from the air layer is For example, when the material of the light guide plate 1 is polycarbonate (PC) resin, the refractive index n of the polycarbonate resin is n = 1.59.
Therefore, the light ray L0 entering the light guide plate 1 from the air layer is 0 ≦ | α | ≦ sin ⁻¹ (1 / n) (where n is an air layer and the refractive index n = 1). The light present inside is in the range of approximately refraction angle α = ± 38.9713 °.

Light incident on the light guide plate 1 within the range of the refraction angle α = ± 38.9713 ° is sin γ = (at the boundary surface between the light guide plate 1 and the air layer (refractive index n = 1). 1
The critical angle can be represented by / n). For example, the refractive index of a polycarbonate resin, which is a resin material used for a general light guide plate 1, is about n = 1.59, so that the critical angle γ is about γ = 38.97 °. The light guide plate 1
When an acrylic resin (PMMA) material is used as the material of, the refractive index n of the acrylic resin is about n = 1.49, and the refraction angle α is about α = 42.38 °. Also becomes about γ = 42.38 °.

In FIG. 3, the surface portion 5 and the back surface portion 6 of the light guide plate 1 on the incident portion P side are shown as plane portions, but these represent the base planes of the surface portion 5 and the back surface portion 6. so,
Actually, a convex ridge 51 or a ridge 61 or a concave ridge 52 or a ridge 6 is formed from the end of the center position P1 of the incident part P or the one end position P2.
Two triangular shapes are provided.

Therefore, as shown in FIG. 4, the rays L1 and L1 'which have traveled in the direction of the front surface 5 and the back surface 6 at the maximum refraction angle α have sides 5b formed at an angle θ3 with the virtual horizontal plane 1c and the virtual horizontal plane 1d, as shown in FIG. An angle (incident angle) formed with the perpendicular of the side 6b is smaller than the critical angle γ, breaks the critical angle γ, and is refracted and emitted as a light ray L12 or a light ray L12 ′ as along the front surface portion 5 or the back surface portion 6.

In the case of light rays having a small refraction angle α such as the light rays L2 and L2 ′, the angle (incident angle) formed by the perpendiculars of the sides 5b and 6b is larger than the critical angle γ, and thus the light ray L3. Or L3 'to be totally reflected. The light rays L3 and L3 ′ have an angle (incident angle) formed with the perpendiculars of the sides 6b and 5b smaller than the critical angle γ, so the light rays L3 and L3 ′ are broken and refracted to form the light rays L4 and the light rays L4 ′. 6 and the front surface portion 5 are emitted at a certain angle along the front surface portion 5 and the back surface portion 6.

As described above, a cross section in a direction perpendicular to the normal to the convex ridges 51 and ridges 61 and the concave ridges 52 and ridges 62 radially provided on the front surface portion 5 and the rear surface portion 6 from the incident portion P of the present invention. In the triangular angle range of, most of the light rays emitted from the front surface portion 5 are light rays totally reflected by the side 6b of the convex ridge 61 provided on the back surface portion 6. Most of the light rays emitted from the back surface portion 6 are the sides 5 b of the convex ridge 51 provided on the front surface portion 5.
It is a ray totally reflected at.

Among the light rays existing in the light guide plate 1 (approximately within the range of the refraction angle α = ± 38.97 °), the smaller the refraction angle α, the greater the energy of the light. The main light rays are not the light rays that are directly emitted, but the light rays that are once totally reflected by the side 6b of the convex ridge 61. That is,
Most of the light rays emitted from the front surface portion 5 are light rays with large energy of light totally reflected by the side 6 b of the convex ridge 61 provided on the back surface portion 6.

The emitted light is emitted along the front surface portion 5 and the back surface portion 6. Although not shown, the ridge 51 and the ridge 61 are provided on the front surface portion 5 or the back surface portion 6 depending on the purpose.
It may be provided only in this case, and an effect equivalent to that of the above-described configuration is obtained. For example, a convex ridge 51 or a concave ridge 5 only on the surface portion 5
2 is provided so that most of the emitted light is emitted from the direction of the back surface portion 6, and light from the lower direction of the back surface portion 6 such as reflected light is emitted from the front surface portion 5.
It can be used for a front light that emits light in any direction.

Further, as the distance from the light source 2 increases, the pitch between the convex ridges 51 and 61, the concave ridges 52 and 62, etc. is changed, and the height of the convex ridges 51 and 61 is increased. It is also possible to set the depth of the ridges 52 and 62 having the concave shape. As a result, it is possible to change the amount of light rays reaching the side 5b, the side 6b, etc., and change the amount of emitted light.

Further, in the light guide plate 1, when the convex ridges 51 and ridges 61 and the concave ridges 52 and ridges 62 are continuous as shown in FIG. , The ridges 61, the ridges 52, and the ridges 62 are radiated from the emitted light source 2
Are at the same distance from each other, and all the light energies of all the ridges at an arbitrary distance corresponding thereto are emitted equally.

Further, in the light guide plate 1, as shown in FIG. 5B, when the convex ridges 51 and 61 and the concave ridges 52 and 62 are discontinuous, the light is incident from the light source 2 and the ridge 51, The light rays reaching the ridge 61, the ridge 52, and the ridge 62 are the light sources 2 for emitting and emitting light.
The same optical energy is emitted only to the ridges that are at the same distance from, but are at any distance corresponding to them. Thereby, the light emitted from the front surface portion 5 and the back surface portion 6 can be partially emitted to a target position.

Further, as shown in FIG. 6, the light guide plate 1 may be provided with a flat portion 511 and a flat portion 521 in which a triangular ridge portion is cut flat. Further, although not shown, for example, in the case where a flat portion 511 that is cut flat on the ridge 51 is provided only on the front surface portion 5 and a reflector is provided in the vicinity of the back surface portion 6, total reflection is performed on the front surface portion 5. The light travels in the direction of the back surface portion 6, the light rays emitted from the back surface portion 6 to the outside are reflected by the reflector, and the light rays that enter the light guide plate 1 again are reflected at the slopes (sides) of the ridges 51 of the front surface portion 5. Refracts, but flats 51
In the case of 1, the light can be emitted from the surface portion 5 in a substantially straight line.

Although not shown here, by providing a flat portion on the back surface portion 6 as well, light can be emitted substantially straight from the flat portion provided on the back surface portion 6 by the same action.

Further, as shown in FIG. 7, adjacent surfaces (sides) of the triangular ridges of the light guide plate 1 may be curved or arcuate. FIG. 7 shows ridge surfaces 51a and 51b that are curved or arcuately indented. As a result, when the light existing in the light guide plate 1 reaches the concave ridge surface 51a, the emission angle becomes larger than the straight edge with respect to the normal line of the surface 51a, and diffuses outward. It will be in the state of doing.

Although not shown, in the case where the curved or arcuate surface is a ridge surface that bulges outward, the light existing in the light guide plate 1 reaches this bulged convex ridge surface. The emission angle is smaller than the straight ridge with respect to the normal, and the state is closer to the inner side, and the light is condensed at the place where the curvature matches, and the light is diffused when the distance is further. In this way, the light guide plate 1
When the adjacent surfaces (sides) of the triangular ridges are curved or arcuate, the emission angle of the emitted light can be changed.

The convex ridges 51 and ridges 61 and the concave ridges 52 and ridges 62 have the same side 5a and side 5b and side 6a and side 6b, but it is an object of the present invention. The light may be emitted from the light guide plate 1 in the direction opposite to the incident part P of the surface portion 5 of the light guide plate 1. Therefore,
The shape does not have to be an isosceles triangle, and may be, for example, a right-angled triangle having only the sides 5b and 6b and having the sides 5a and 6a perpendicular.

Here, FIG. 8 is a partially enlarged sectional view of the light polarizing sheet of the flat lighting device according to the present invention, and FIG. 9 is arranged at the center position of the side surface portion of the light polarizing sheet where the light source corresponds to the light guide plate. FIG. 10 is a plan view of the light polarizing sheet in the case, and FIG. 10 is a plan view of the light polarizing sheet in the case where the light source is arranged at one end position of the side surface of the light polarizing sheet corresponding to the light guide plate.

The light polarizing sheet 10 is made of acrylic resin (PM
It is formed into a film from a transparent resin such as MA) or polycarbonate (PC). As shown in FIG. 8, the light polarizing sheet 10 has a shape corresponding to the light guide plate 1, has a triangular cross section, and includes a convex ridge 10a and a concave ridge 10b. The light polarization sheet 10 is similar to the light guide plate 1 in the light guide plate 1.
Depending on how to use, the ridges 10 which are not shown in the drawings but have a convex shape are scattered.
a is provided, or concave ridges 10b are provided at intervals,
It is also possible to make a plane between the convex edge 10a and the concave edge 10b.

The light polarizing sheet 10 is, as shown in FIG.
Angle θ5 of convex ridge 10a and angle θ6 of concave ridge 10b
Is in the range of 60 to 80 degrees. Further, the light polarizing sheet 10 has an angle θ7 formed with the virtual horizontal plane 11a parallel to the surface portion 11 within a range of 20 degrees to 60 degrees.

Further, in order to make the light polarizing sheet 10 correspond to the light guide plate 1, the center position P1 of the side surface portion 4 of the light guide plate 1 is set.
When the light source 2 is provided opposite to the incident portion P, the convex ridges 10a and the concave ridges 10 provided radially on one side from the incident portion P, here, on the back side of the front surface portion 11, as shown in FIG.
b is the direction a perpendicular to the normal line of the ridge concentric with the incident portion P at the center position
A line having a triangular cross section shown in FIG.

In the case where the light source 2 is provided at one end position P2 of the side surface portion 4 of the light guide plate 1 so as to face the incident portion P, the light polarizing sheet 10 is radially radiated from the incident portion P as shown in FIG. The convex ridges 10a and the concave ridges 10b provided on the back side of the front surface portion 11 are illustrated on one side as a line P-b connecting the normal to the incident portion P at the central position and the normal to the ridge and the perpendicular direction b. A triangular cross section as shown in 8 is provided.

Further, in the light polarizing sheet 10, the convex ridges 10a are the lines S1 and the concave ridges 10 as in the light guide plate 1.
b is provided radially like line S2 and has a convex ridge 1
0a is the line S1, S3 (odd number), and the concave edge 10b
As lines S2 and S4 (even number), convex and concave shapes are formed alternately or continuously (line Sn).

Although the sides 12a and 12b of the convex ridge 10a and the concave ridge 10b here have the same shape,
The light guide plate 1 may have a shape suitable for the light emitted from the surface portion 5, and may not be an isosceles triangle.

Next, FIG. 11 is a partially enlarged view of a flat illumination device including a light guide plate and a light polarizing sheet according to the present invention, and is a view showing a locus of light rays.

The flat lighting device is provided with the light polarizing sheet 10 on the upper portion of the light guide plate 1, and the convex ridges 10a of the light polarizing sheet are provided on the light guide plate 1 so as to face the convex ridges 51 provided on the light guide plate 1. The light source 2 is arranged toward the front surface 5 side, and the light source 2 is arranged at the center position or one end position of the side surface of the light guide plate 1.

Here, since the description of the light guide plate 1 and the light polarizing sheet 10 overlaps with the above description, the description thereof will be omitted and the trajectory of the light will be described.

In FIG. 11, among the light rays that have entered the inside of the light guide plate 1 from the incident portion P, the light ray L 0 that has proceeded in the direction of the surface portion 5 with the maximum refraction angle α is the side 5 b of the convex ridge 51 of the surface portion 5.
To reach.

When the front surface 5 is a flat surface with respect to this light ray L0, total reflection is performed and the light travels in the direction of the rear surface 6, but the side 5b.
Since the incident angle is smaller than the critical angle γ = 38.97 °, the critical angle γ is broken and refracted, and the light ray L1 is emitted to the air layer.

The light ray L1 at this time is the surface portion 5 of the light guide plate 1.
The light is emitted at a large emission angle such as along.

Next, the light ray L1 reaches the side 12b of the convex ridge 10a of the light polarizing sheet 10, and the light guide plate 1 and the light polarizing sheet 10 are also made of the same material (polycarbonate (PC)). The light ray L1 from the air layer to the side 12b of the light polarizing sheet 10 having a larger refractive index than air is refracted at the side 12b and travels into the light polarizing sheet 10 as a light ray L11.

Further, the light ray L11 is reflected by the light polarizing sheet 10.
Reaches the inner side 12a, and the incident angle here is the critical angle γ = 3
Since the angle is larger than 8.97 °, the light ray L12 is totally reflected by the side 12a and travels toward the surface portion 11 of the light polarizing sheet 10.

Since the incident angle of the light ray L12 on the surface portion 11 of the light polarizing sheet 10 is smaller than the critical angle γ = 38.97 °, it is emitted from the surface portion 11 substantially vertically.

As described above, the light polarizing sheet 10 emits light rays from the light guiding plate 1 which are low along the light guiding plate 1 in a direction substantially perpendicular to the light polarizing sheet 10 using total reflection. can do.

As described above, the flat lighting device of the present invention is provided with the light polarizing sheet 10 on the light guide plate 1,
A light beam emitted from the light guide plate 1 along the light guide plate 1 can be emitted from above the planar illumination device as a whole by the light polarizing sheet 10.

Further, the flat lighting device comprising the light guide plate 1 and the light polarizing sheet 10 of the present invention can be used with a small number of point light sources.
Radial ridges are provided on the front surface portion 5 and the back surface portion 6 of the light guide plate 1 from the position where the light source is located, and a constant light energy is given everywhere, and a light beam having a large light energy among the light beams entering the light guide plate 1 is guided. The light is emitted from the light plate 1 at an arbitrary angle and is polarized in the substantially vertical direction by the light polarizing sheet 10, whereby uniform high brightness can be obtained as a flat lighting device.

[0091]

As described above, in the light guide plate according to the first aspect, the incident portion is located at the center position of at least one side surface portion, and the front surface portion and / or the back surface portion is convex or concentric with the center position. Since it has a concave ridge and the light energy is equally emitted from the light source at an arbitrary distance corresponding to the ridge, it can be emitted with uniform brightness anywhere on the front surface or the back surface of the light guide plate. .

Further, in the light guide plate according to the second aspect, the incident part is at least at one end position of the side surface part, and the front surface and / or the back surface part is provided with a convex or / and concave ridge concentrically with the end position. Since the light energy is equally emitted from the light source at an arbitrary distance corresponding to the ridge, it is possible to emit light with uniform brightness anywhere on the front surface and the back surface of the light guide plate, and the light source has a certain degree of brightness. Even in the case of a rectangular shape having a size of, since the incident portion has a maximum spread of 90 degrees, the radiation angle of the light source can be allowed.

Further, in the light guide plate according to the third aspect, since the cross section in the direction perpendicular to the normal to the ridge at the center position or the one end position and the concentric direction is always triangular, the emission angle from the front surface or the back surface is reduced. It is possible to obtain emitted light having substantially the same value.

Further, in the light guide plate according to the fourth aspect, since the ridge is continuous or discontinuous, not only the emitted light can be emitted from the front surface and the back surface to the entire area along the ridge, but also
It can also be partially emitted to a target position.

Further, in the light guide plate according to the fifth aspect, since the angles of the triangular ridges are in the range of 80 degrees to 179 degrees, the intervals between the ridges are changed as the angles of the ridges in the light guide plate change. It can be adjusted and the pitch between the ridges can be set shorter as the distance from the light source increases, and the height or depth of the convex or concave ridge can be set. Then, as the distance from the light source increases, the pitch between the ridges becomes shorter, the height of the convex ridges becomes higher, or the depth of the concave ridges becomes deeper, so that the attenuation of the light intensity from the light source is emitted. Uniform emission light can be obtained by controlling the amount.

In the light guide plate according to the sixth aspect, the angle formed by the triangular shape with the virtual horizontal plane of the front surface portion and / or the back surface portion is in the range of 0.01 to 10 degrees. It can be changed to adjust the distance between the ridges, and the pitch between the ridges can be set shorter as the distance from the light source increases, and the height or depth of the convex or concave ridge can be set. can do. Then, as the distance from the light source increases, the pitch between the ridges becomes shorter, the height of the convex ridges becomes higher, or the depth of the concave ridges becomes deeper, so that the attenuation of the light intensity from the light source is emitted. Uniform emission light can be obtained by controlling the amount. .

Further, in the light guide plate according to the seventh aspect, since the triangular ridge portion is flatly cut, for example, the flat ridge portion is provided only on the front surface portion, and the reflector is provided near the back surface portion. In the case where it is provided, the light totally reflected on the front surface portion, the light ray that has traveled in the direction of the rear surface portion and is emitted from the rear surface portion to the outside, is reflected by the reflector and is incident on the light guide plate again. Although reflection and refraction are performed on the sloped surface, in the flat portion of the present invention, it is possible to emit the light from the surface portion substantially straightly. Therefore, for example, in a usage such as a front light, straight traveling light is emitted from the upper portion of the light guide plate. It can be observed.

Further, in the light guide plate according to the eighth aspect, since the adjoining surfaces of the triangular ridges are curved or arcuate, when the curved or arcuate ridges are indented inward, In the case of a ridge surface with a curved or arcuate bulge outwards, light is condensed at a location that matches the curvature,
Since the emission angle of the emitted light can be varied so that the light is diffused further away, it is possible to design according to the purpose.

Further, the flat illumination device according to claim 9 is
A light source, a light guide plate having a central position of at least one side face as an incident part, and a convex or / and concave ridge concentric with the central position on the front face or / and the back face, and a position corresponding to the ridge And a light-polarizing sheet having an arc-shaped prism shape in relation to each other, and the light emitted from the light guide plate with equal light energy from the light source at an arbitrary distance corresponding to the ridge is front surface portion and / or back surface portion by the light polarizing sheet. Since the light is emitted in a direction substantially at a right angle, the emitted light is obtained from the entire front surface with respect to the observation side, and when used in a liquid crystal display device or the like, it is possible to obtain an appropriate viewing angle without bright spots.

The flat lighting device according to the tenth aspect of the present invention is
The light source and at least one end portion of the side surface is the incident portion,
A light guide plate having a convex or / and concave ridge concentric with an end position on a front surface portion and / or a back surface portion, and a light polarizing sheet having an arc-shaped prism shape in a positional relationship corresponding to the ridge. , Since the light emitted from the light guide plate has the same light energy at an arbitrary distance corresponding to the ridge from the light source, the light is emitted in a direction substantially perpendicular to the front surface portion and / or the back surface portion by the light polarizing sheet. The emitted light can be obtained from the entire front surface, and when used in a liquid crystal display device or the like, it is bright and has no spots and an appropriate viewing angle can be obtained.

Furthermore, in the flat illumination device according to the eleventh aspect, the light polarizing sheet is provided with a convex shape or a / corresponding to the center position from the center position of the side surface portion of the light guide plate and the position concentric with the ridge of the light guide plate.
Since it has a concave ridge and a concave ridge, the light emitted from the convex or concave ridge of the light guide plate can be completely guided to the convex or concave ridge of the present light polarizing sheet at the shortest distance. Light emitted from the light plate can be polarized.

Further, the flat illumination device according to claim 12 is
Since the light polarizing sheet has convex or / and concave ridges corresponding to the end position of the light guide plate and the position concentric with the ridge of the light guide plate, the light emitted from the convex or concave ridge of the light guide plate Can be guided to the convex or concave ridge of the present light polarizing sheet completely at the shortest distance, and the light emitted from the light guide plate can be polarized by the present light polarizing sheet.

Further, in the flat illumination device according to the thirteenth aspect, the cross section in the direction perpendicular to the normal line to the ridge corresponding to the center position or the end position of the light polarizing sheet is always triangular. Therefore, the light emitted from the light guide plate can be polarized, and, for example, the light emitted from the light guide plate along the light guide plate side can be polarized substantially at right angles.

The flat illumination device according to claim 14 is
Since the light polarizing sheet is continuous or discontinuous, it is possible to selectively polarize the portion requiring polarization with respect to the light emitted from the light guide plate, and it is possible to design according to the purpose.

Furthermore, in the flat illumination device according to the fifteenth aspect, the angles of the triangular edges of the light polarizing sheet are 60 degrees to 8 degrees.
Since it is in the range of 0 degree, the pitch between the ridges and the height or depth of the ridges can be set according to the purpose, and by controlling the amount of light emitted from the light guide plate, the plane illumination It is possible to make the distribution of emitted light from the device uniform.

Furthermore, in the flat illumination device according to the sixteenth aspect, since the angle formed by the triangular shape of the light polarizing sheet and the virtual horizontal plane of the light polarizing sheet is in the range of 20 to 60 degrees, the width of the triangular shape and the mutual shape can be reduced. The pitch between them can be controlled, and by controlling the amount of light that takes in the light emitted from the light guide plate, it is possible to make the distribution of the light emitted from the planar illumination device uniform.

Furthermore, in the flat illumination device according to the seventeenth aspect, the light source and the position of the center or end of at least one of the side faces is the incident part, and the center position or end position is on the front surface and / or the back surface. A light guide plate having a convex or / and concave ridge concentrically with and a light polarizing sheet having a convex or / and concave ridge equal to the ridge of the light guide plate so as to face the ridge. Since the angle of the ridge and the angle of the ridge of the light polarizing sheet are always the same, the angle of the light ray before exiting from the ridge of the light guide plate is equal to the angle of the light ray after entering the ridge of the light polarizing sheet. In addition, the light emitted from the ridge of the light guide plate can be guided to the ridge of the light polarizing sheet completely at the shortest distance and the light can be efficiently polarized. As a result, it is possible to obtain bright and even emission light, and even light rays emitted from the light guide plate along the side of the light guide plate are raised almost vertically without any corners, and are directly facing the observation side. The emitted light is obtained from the entire surface of the.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a light guide plate according to the present invention, which is a plan view of the light guide plate when a light source is arranged at a central position of a side surface portion of the light guide plate.

FIG. 2 is a plan view showing an embodiment of a light guide plate according to the present invention, and is a plan view of the light guide plate when a light source is arranged at one end position of a side surface portion of the light guide plate.

3 is a diagram illustrating a point P1 of the light guide plate shown in FIG. 1 and a line P1-A connecting a normal line of a concentric ridge from the point P1 to a direction A at right angles; and a point P2 of the light guide plate shown in FIG. Sectional view of P2-B connecting the normal line of the ridge and the perpendicular direction B

FIG. 4 is a partially enlarged cross-sectional view of the light guide plate of FIG. 3, showing a ray trajectory.

5A and 5B are partially enlarged views showing another configuration example of the ridges provided in the light guide plate according to the present invention.

FIG. 6 is a partially enlarged view showing another configuration example of a ridge provided on the light guide plate according to the present invention.

FIG. 7 is a partially enlarged view showing another configuration example of a ridge provided on the light guide plate according to the present invention.

FIG. 8 is a partially enlarged cross-sectional view of a light polarizing sheet of a flat lighting device according to the present invention.

FIG. 9 is a plan view of the light polarizing sheet when the light source is arranged at the center of the side surface of the light polarizing sheet corresponding to the light guide plate.

FIG. 10 is a plan view of the light polarizing sheet when the light source is arranged at one end of the side surface of the light polarizing sheet corresponding to the light guide plate.

FIG. 11 is a partially enlarged view of a flat lighting device including a light guide plate and a light polarizing sheet according to the present invention, showing a trajectory of light rays.

[Explanation of symbols]

1 ... Light guide plate, 2 ... Light source, 4, 7, 8, 9 ... Side part, 5,
11 ... Front surface portion, 6 ... Back surface portion, 10 ... Light polarizing sheet, n ...
Refractive index, 51, 61, 10a ... Convex ridge, 52, 62, 1
0b ... concave edge, 1c, 1d, 11a ... virtual horizontal plane, A,
B, a, b ... Point in the vertical direction of the normal line concentric with the light source, 51
1, 521 ... Flat portion, 51a, 52a ... Curved ridge, 5a,
5b, 12a, 12b ... Side, P ... Incident part, P1 ... Center position, P2 ... One end position, S1 ... Convex edge line, S2 ... Concave edge line, Sn ... Line, α ... Refraction angle, θ1, θ5 ... Convex Angle of the curved ridge, θ2, θ6 ... Angle of the concave ridge, θ3, θ7 ... Angle formed by virtual horizontal line, γ ... Critical angle, L0, L1, L2
L1 ', L2'L3, L3', L4, L4 ', L12,
L12 ', L13, L13', L31, L32, L3
3, L34 ... Rays.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21Y 101: 02 F21Y 101: 02 F term (reference) 2H038 AA55 BA06 2H091 FA21Z FA23Z FA41Z FB02 FD06 FD22 LA18

Claims (17)

[Claims] 1. An incident portion for guiding light from a light source, a front surface portion for emitting the light, a back surface portion located on the opposite side of the front surface portion, and the front surface portion and the back surface portion intersecting each other at a right angle. In the light guide plate having a side surface portion, the incident portion has a center position of at least one of the side surface portions, and has a convex or / and concave ridge concentric with the central position on the front surface portion and / or the back surface portion. The light guide plate emits equal light energy from the light source at an arbitrary distance corresponding to the ridge. 2. An incident portion for guiding light from a light source, a front surface portion for emitting the light, a rear surface portion located on the opposite side of the front surface portion, and the front surface portion and the rear surface portion intersecting each other at a right angle. In the light guide plate having a side surface portion, the incident portion has at least one end position of the side surface portion and has a convex or / and concave ridge concentric with the end portion position on the front surface portion and / or the back surface portion. The light guide plate emits equal light energy from the light source at an arbitrary distance corresponding to the ridge. 3. The light guide plate according to claim 1, wherein the ridge is always triangular in cross section in a direction perpendicular to a normal line between the center position or the end position and the concentricity. . 4. The light guide plate according to claim 1, wherein the ridge is continuous or discontinuous. 5. The light guide plate according to claim 1, wherein the triangular shape has an angle of the ridge in a range of 80 degrees to 179 degrees. 6. The triangular shape forms an angle of 0.01 degree with an imaginary horizontal plane of the front surface portion and / or the back surface portion.
The light guide plate according to claim 1 or 2, wherein the light guide plate has a range of 10 degrees. 7. The light guide plate according to claim 1, wherein the ridge portion of the triangular shape is cut flat. 8. The triangular shape is characterized in that adjacent surfaces of the ridge are curved or arcuate.
The light guide plate according to claim 4 or claim 7. 9. A light source, a light guide plate having a central portion of at least one side surface as an incident portion, and a convex portion and / or a concave ridge concentric with the central portion on a front surface portion and / or a rear surface portion, and A light-polarizing sheet having an arc-shaped prism shape in a positional relationship corresponding to a ridge, and light emitted from the light guide plate having equal light energy at an arbitrary distance from the light source corresponding to the ridge. A planar illumination device, which emits light in a direction substantially perpendicular to the front surface portion and / or the back surface portion by a light polarizing sheet. 10. A light source, a light guide plate having an incident portion at least at one end position of a side surface portion, and a convex or / and concave ridge concentric with the end portion position on a front surface portion and / or a back surface portion, A light-polarizing sheet having an arc-shaped prism shape in a positional relationship corresponding to a ridge, and light emitted from the light guide plate having equal light energy at an arbitrary distance from the light source corresponding to the ridge. A planar illumination device, which emits light in a direction substantially perpendicular to the front surface portion and / or the back surface portion by a light polarizing sheet. 11. The light polarizing sheet has a convex or / and concave ridge corresponding to a position concentric with the central position of the side surface of the light guide plate and the ridge of the light guide plate. The flat illumination device according to claim 9, wherein the flat illumination device is a flat illumination device. 12. The light-polarizing sheet has convex or / and concave ridges corresponding to the end position of the light guide plate and a position concentric with the ridge of the light guide plate. The flat lighting device according to claim 10. 13. The ridge of the light polarizing sheet is characterized in that a cross section in a direction perpendicular to a normal line between the center position or the end position and the ridge corresponding to the concentric position is always triangular. The flat lighting device according to claim 9 or 10. 14. The flat lighting device according to claim 9, wherein the light polarizing sheet is continuous or discontinuous. 15. The flat illumination device according to claim 9, wherein the light polarizing sheet has an angle of the ridge of the triangular shape in a range of 60 degrees to 80 degrees. 16. The light polarizing sheet has an angle of 20 ° to 6 between the triangular shape and a virtual horizontal plane of the light polarizing sheet.
The light guide plate according to any one of claims 9 to 11, wherein the light guide plate has a range of 0 degree. 17. A light source and a center or an end position of at least one side surface as an incident part, and a convex shape and / or a concave shape concentric with the center position or the end position on the front surface part and / or the back surface part. And a light polarizing sheet having a convex or / and concave edge that is equal to the edge of the light guide plate so as to face the edge, and the angle of the edge of the light guide plate A flat illumination device characterized in that the angle of the ridge of the light polarizing sheet is always the same.