JP4182075B2 - Light guide plate and flat illumination device - Google Patents

Description

  In the present invention, a substantially triangular prism or circular arc column having a plurality of ridges having different heights on the front surface portion and the back surface portion of the light guide plate is extended in a substantially perpendicular direction to the incident end surface portion. Because even if the apex angles of the prisms are the same, the height of the triangles and arc columns is different, so the spread range of the emitted light is different from the incident angle under the same conditions, and the pitch and ridge height of the triangle and arc columns are also different. However, since the heights of the triangular prisms and arcuate columns are not constant (equivalent), the optical members provided above the surface part and the reflections provided below the back part are mechanically available. The present invention relates to a light guide plate and a flat illumination device that can prevent a sheet or the like from sticking to a front surface portion or a back surface portion of the light guide plate.

  As a conventional light guide plate, a convex portion having a pair of inclined surfaces extending in a direction substantially orthogonal to an end surface to which light is incident is repeatedly formed in a direction substantially parallel to the end surface to form a prism shape. Things are known.

In addition, as a conventional light guide plate, with respect to the front surface portion and the back surface portion, a prism shape such as a triangle shape or a semicircular shape such that the cross-sectional shape is perpendicular or inclined with respect to the incident end surface, or these are mounted in a jumping manner. Things are also known.
JP-A-11-002730 JP 09-061631 A

  All of the conventional light guide plates described above are provided with prism shapes on the front and back portions of the light guide plate for purposes such as light deflection, light condensing, or diffusion. Equivalent). For this reason, an optical member provided above the surface portion that is the emission direction of the light guide plate, a reflective sheet provided below the back surface portion that is opposite to the emission direction of the light guide plate, and the like are attached to the surface portion and the back surface portion of the light guide plate. Therefore, there are problems that optically obstruct the action, such as changing the deflection direction of the target light or generating locally more light (bright lines).

  The present invention has been made to solve the above-described problems, and has a ridge having different heights extending in a direction substantially perpendicular to the incident end surface portion on the front surface portion and / or the back surface portion of the light guide plate. The cross-sectional shape of the apex of the ridge is a triangular or / and arc-shaped substantially triangular prism or / and a plurality of arc columns arranged side by side, because the height is different even if the apex angle of the ridge is optically equal In addition, since the spread range of the emitted light is different with respect to the incident angle of the substantially triangular prism or arc column under the same conditions, and the pitch and ridge height of the approximately triangular prism or arc column are different, different output light amounts can be obtained. By controlling the spread range of the emitted light and the amount of emitted light according to the purpose, it is possible to obtain uniform and high-intensity emitted light, change the deflection direction of the target light, or locally exceed the light ( Generation of bright lines), etc. The optical sheet provided above the front surface part and the reflective sheet provided below the back surface part because the hindrance of the action can be prevented and the height of the substantially triangular column or arc column is not constant (equivalent) mechanically. Can be prevented from sticking to the front and back parts of the light guide plate, and there is no wear on the edges of the triangular or arc column, especially when used for many years. An object of the present invention is to provide a light guide plate and a flat illumination device that can be used.

In the light guide plate according to claim 1 of the present invention, a substantially triangular column or / and an arc column having ridges with different heights extending in a direction substantially perpendicular to the incident end surface portion on the front surface portion and / or back surface portion are provided in the lateral direction. It is characterized by being arranged in a regular manner .

The light guide plate according to claim 1 is provided with regular triangular pillars and / or circular arc pillars having ridges having different heights extending in a substantially perpendicular direction to the incident end face part on the front surface part and / or the back face part in the lateral direction. since arrayed plurality have substantially triangular prism and arc with the spread range of the emitted light are different with respect to the incident angle at the same conditions of triangular prism or circular arc column to the at optically equal apex angle of crest height varies Since the pitch of the pillars and the height of the ridges are different, different amounts of emitted light can be obtained.

  In addition, since the height of the substantially triangular column or arc column is not constant (equivalent) mechanically, the optical component provided above the surface portion, the reflection sheet provided below the back surface portion, etc. It can prevent sticking to a part.

  The light guide plate according to claim 2 is characterized in that the cross-sectional shape of the top portion of the ridge is triangular or / and arcuate.

  In the light guide plate according to claim 2, since the cross-sectional shape of the top portion of the ridge is a triangle shape and / or an arc shape, there is no great difference optically, but mechanically an optical component provided above the surface portion. The contact area is smaller when the cross-sectional shape of the top portion of the ridge is a triangular shape with respect to the reflection sheet or the like provided below the back surface portion. Further, although depending on the material of the light guide plate, the change in the wear of the contact portion over time is smaller when the cross-sectional shape of the top portion of the ridge is an arc shape.

  Furthermore, the light guide plate according to claim 3 is characterized in that the surface connected to the ridge of the substantially triangular prism is a straight line or a curve.

  In the light guide plate according to claim 3, since the surface connected to the ridge of the substantially triangular prism is a straight line or a curve, the same direction with respect to the incident angle from the same direction when the surface connected to the ridge of the approximately triangular prism is a straight line When the surface connected to the ridge of the substantially triangular prism is a curve, the normal line always changes, so that all the emission angles are emitted at different emission angles.

  The light guide plate according to claim 4 is characterized in that the distance between adjacent edges is in the range of 30 to 150 microns.

  In the light guide plate according to the fourth aspect, the distance between adjacent edges is in the range of 30 to 150 microns. Therefore, even when a substantially triangular prism or arc pillar is continuously provided, the height of the light guide plate is changed by the change in the adjacent distance between the edges. Different ridges can be obtained and, for example, when the liquid crystal display device is placed above these light guide plates, the pitch of the liquid crystal pixels of the liquid crystal display device does not match the pitch of the substantially triangular column or arc column provided on the light guide plate. Can be selected.

  Furthermore, the light guide plate according to claim 5 is characterized in that the intervals between different heights of the ridges are in the range of 1 to 10 microns.

  In the light guide plate according to claim 5, since the interval between different heights of the ridges is in the range of 1 to 10 microns, the height is different even if the apex angles of the ridges are optically equal. Since the range of the emitted light is different for the incident angle under the same conditions, the amount of emitted light is different. However, since the height interval range is very small, spots are not generated in the emitted light, and the height is constant (equal ), It is possible to prevent the optical component provided above the front surface portion, the reflection sheet provided below the back surface portion, and the like from sticking to the front surface portion and the back surface portion of the light guide plate.

Moreover, the flat illumination device according to claim 6 includes a light source,
An incident end face part that guides light from the light source, a surface part that emits the light guided from the incident end face part to the outside, a back face part that is located on the opposite side of the front face part, these front face part, back face part, and incident end face part A regular triangular column and / or circular arc column with ridges with different heights extending in a direction substantially perpendicular to the incident end surface on the front surface and / or back surface . a plurality lined LGP with,
A reflector that surrounds the light source other than the portion facing the incident end face of the light guide plate;
A reflector provided in the vicinity of the back surface;
The light source, the light guide plate, the reflector, and a case for storing at least a reflector are provided.

The flat illumination device according to claim 6 includes a light source,
An incident end face part that guides light from the light source, a surface part that emits the light guided from the incident end face part to the outside, a back face part that is located on the opposite side of the front face part, these front face part, back face part, and incident end face part A regular triangular column and / or circular arc column with ridges with different heights extending in a direction substantially perpendicular to the incident end surface on the front surface and / or back surface . a plurality lined LGP with,
A reflector that surrounds the light source other than the portion facing the incident end face of the light guide plate;
A reflector provided in the vicinity of the back surface;
Since the light source plate has a case for accommodating at least the light guide plate, the reflector, and the reflector, the light guide plate is optically equal in the apex angle of the ridge, so that the height is different. Since the spread range of the emitted light is different with respect to the incident angle, and the pitches and the heights of the ridges of the substantially triangular column and the arc column are different, different amounts of emitted light can be obtained.

  In addition, since the height of the substantially triangular column or arc column is not constant (equivalent) mechanically, the optical component provided above the surface portion, the reflection sheet provided below the back surface portion, etc. In particular, when used for many years, there is no wear on the ridges of the substantially triangular column and the arc column, and it is possible to obtain a high-intensity outgoing light with no spots over a long period of time.

As described above, the light guide plate according to claim 1 has a substantially triangular prism or / and a circular arc column with ridges having different heights extending in a direction substantially perpendicular to the incident end surface on the front surface and / or back surface. Since a plurality of lines are arranged with regularity in the direction, the height of the ridges is optically the same, but the height is different. At the same time, since the pitches and heights of the ridges of the substantially triangular prisms and arcuate pillars are different, different amounts of emitted light can be obtained. Therefore, uniform and high-intensity outgoing light can be obtained by controlling the spreading range of the outgoing light and the amount of outgoing light according to the purpose.

  In addition, since the height of the substantially triangular column or arc column is not constant (equivalent) mechanically, the optical component provided above the surface portion, the reflection sheet provided below the back surface portion, etc. It can prevent sticking to a part. For this reason, it is possible to prevent the optical action from being hindered, such as changing the deflection direction of the target light or locally generating more light (bright lines) than necessary.

  Further, the light guide plate according to claim 2 is optically not significantly different because the cross-sectional shape of the top portion of the ridge is triangular or / and arc-shaped, but mechanically provided above the surface portion. The contact area is smaller when the cross-sectional shape of the top portion of the ridge is triangular with respect to the optical component, the reflection sheet provided below the back surface portion, and the like. Further, although depending on the material of the light guide plate, the change in the wear of the contact portion over time is smaller when the cross-sectional shape of the top portion of the ridge is an arc shape. Therefore, an optical member provided above the front surface portion, a reflective sheet provided below the back surface portion, an optical member provided above the front surface portion corresponding to the material of the light guide plate, a reflective sheet provided below the back surface portion, etc. In contrast, it can be prevented from sticking to the front surface portion or the back surface portion.

  Furthermore, the light guide plate according to claim 3 is such that the surface connected to the ridge of the substantially triangular prism is a straight line or a curve. Therefore, when the surface connected to the ridge of the approximately triangular prism is a straight line, the incident angle from the same direction is When the surface connected to the ridge of the substantially triangular prism is curved, the normal is always changed, so that all the emission angles are emitted at different emission angles. Therefore, uniform and high-luminance outgoing light can be obtained as a whole of the light guide plate by controlling according to the purpose.

  In the light guide plate according to the fourth aspect, the interval between adjacent ridges is in the range of 30 to 150 microns. Therefore, even when a substantially triangular prism or arc column is continuously provided, the height of the light guide plate is increased by the change in the adjacent interval between the ridges. For example, when the liquid crystal display device is placed above the light guide plate, the pitch of the liquid crystal pixels of the liquid crystal display device matches the pitch of the substantially triangular column or arc column provided on the light guide plate. You can choose not to. Therefore, the generation of moire can be prevented.

  Furthermore, since the light guide plate according to claim 5 has an interval between different heights of the ridges in the range of 1 to 10 microns, the height is different even if the apex angles of the ridges are optically equal. The amount of emitted light differs because the spread range of the emitted light is different with respect to the incident angle of the column under the same conditions, but the height interval is small and the height is constant because the height interval range is minute. Since it is not (equivalent), it is possible to prevent the optical component provided above the front surface portion, the reflection sheet provided below the back surface portion, and the like from sticking to the front surface portion and the back surface portion of the light guide plate. Therefore, it is possible to prevent the obstruction of the optical action such as changing the direction of deflection of the target light while being able to obtain high-intensity outgoing light, and locally generating more light (bright lines) than necessary. Can do.

Moreover, the flat illumination device according to claim 6 includes a light source,
An incident end face part that guides light from the light source, a surface part that emits light guided from the incident end face part to the outside, a back face part that is located on the opposite side of the front face part, and these front face part, back face part, and incident end face part A regular triangular column and / or circular arc column with ridges with different heights extending in a direction substantially perpendicular to the incident end surface on the front surface and / or back surface . a plurality lined LGP with,
A reflector that surrounds the light source other than the portion facing the incident end face of the light guide plate;
A reflector provided in the vicinity of the back surface;
Since the light source plate has a case for accommodating at least the light guide plate, the reflector, and the reflector, the light guide plate is optically equal in the apex angle of the ridge, so that the height is different. Since the spread range of the emitted light is different with respect to the incident angle, and the pitches and ridge heights of the substantially triangular prisms and arcuate columns are different, different emitted light amounts can be obtained.

  In addition, since the height of the substantially triangular column or arc column is not constant (equivalent) mechanically, the optical component provided above the surface portion, the reflection sheet provided below the back surface portion, etc. It can prevent sticking to a part. Therefore, uniform and high-brightness outgoing light can be obtained by controlling the range of outgoing light and the amount of outgoing light according to the purpose, and the target light deflection direction can be changed or locally required. It can prevent optical effects such as the generation of the above light (bright lines), and there is no wear on the edges of the triangular or arc column, especially when used for many years. You can get light. However, it is possible to obtain a stable and high-luminance flat illumination device having a long life.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the present invention, a substantially triangular prism or an arc column extends on the front surface portion or the back surface portion of the light guide plate in a direction substantially perpendicular to the incident end surface portion, and the cross section of the apex portion of the ridge of the approximately triangular column or arc column Because the shape is triangular or arc-shaped, and a plurality of approximately triangular prisms or arc columns with ridges with different heights are arranged side by side in the lateral direction. Since the spread range of the emitted light is different with respect to the incident angle of the substantially triangular column or the arc column under the same conditions, and the pitch and the ridge height of the substantially triangular column or the arc column are different, different amounts of emitted light can be obtained. By controlling the spread range and the amount of emitted light according to the purpose, it is possible to obtain uniform and high-intensity emitted light, change the deflection direction of the target light, or locally exceed the light (bright line) ) To prevent optical effects such as occurrence In addition, since the height of the substantially triangular column or arc column is not constant (equivalent) mechanically, the optical member provided above the surface portion, the reflection sheet provided below the back surface portion, etc. A light guide plate and flat illumination that can prevent sticking to the back surface, can produce high-intensity emission light with no spots over a long period of time, especially when there is no wear on the edges of a substantially triangular or circular arc column during long-term use A device is provided.

  FIG. 1 is a schematic perspective view showing an example of a flat illumination device according to the present invention, FIGS. 2 to 7 are schematic cross-sectional views showing examples of ridges provided on a light guide plate according to the present invention, and FIGS. FIG. 10 is a schematic perspective view showing another example of the flat illumination device according to the present invention.

  As shown in FIG. 1, the flat illumination device 1 (1 </ b> A) includes a light source 10, an incident end face portion 3 that is provided near the light source 10 and guides light from the light source 10, and light guided from the incident end face portion 3. A front surface portion 4 that exits to the outside, and a back surface portion 5 that is located on the opposite side of the front surface portion 4 and has substantially triangular prism ridges having ridges with different heights extending in a direction substantially perpendicular to the incident end surface portion 3; The light guide plate 2 (2A) including the front surface portion 4, the back surface portion 5 and the side surface portion 6 connected to the incident end surface portion 3 and the portion other than the portion facing the incident end surface portion 3 of the light guide plate 2A in the light source 10 are enclosed. The reflector 11 is provided in the vicinity of the back surface portion 5, and the light source 10, the light guide plate 2 </ b> A, the reflector 11, and the reflector 12 are at least housed in the case 13.

  The light guide plate 2 is formed of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7. The light guide plate 2 has fine dots of the light deflection element 14 on the surface portion 4. Further, on the back surface portion 5 of the light guide plate 2, substantially triangular prisms 7 a and 7 b having ridges 8 having different heights extend in a direction substantially perpendicular to the incident end surface portion 3. A plurality of the substantially triangular prisms 7 a and 7 b are continuously arranged along the side surface portion 6.

Further, the light guide plate 2 </ b> A in the example of FIG. 1 has a wedge shape such that the thickness decreases from the incident end surface portion 3 toward the counter incident end surface portion 3 b located on the opposite side of the incident end surface portion 3.
1 has a triangular cross-sectional shape at the apex of the ridge 8 of the substantially triangular prism 7a or the substantially triangular prism 7b, and the surface 9 connected to the ridge 8 is a straight line.

Although not shown here, the substantially triangular prism 7a or the substantially triangular prism 7b as the ridges may have a circular cross section at the top of the ridge 8, and the surface 9 connected to the ridge 8 may be a straight line.
Although not shown here, the ridges may be provided with a predetermined interval so that the substantially triangular prism 7a and the substantially triangular prism 7b are discontinuous and jumped to the back surface portion 5, and the substantially triangular prism 7a and the substantially triangular prism 7b do not exist. The part 5 has a mirror surface.

  2 and 3 is a substantially triangular prism 7a in which the cross-sectional shape of the top portion of the ridge 8 is triangular and the surface 9 connected to the ridge 8 is a straight line in the cross section viewed from the incident end face 3 side. Or a substantially triangular prism 7b. In the example of FIG. 2, the substantially triangular prisms 7 a and the substantially triangular prisms 7 b are alternately provided. In the example of FIG. 3, a plurality of (two in the illustrated example) approximately triangular prisms 7 b are provided between the substantially triangular prisms 7 a. The provided shape is formed.

  Further, the ridge shown in FIG. 4 includes a substantially triangular prism 7c in which the cross-sectional shape of the top portion of the ridge 8 is an arc shape and the surface 9 connected to the ridge 8 is a straight line in the cross section viewed from the incident end face 3 side, 8 are formed by alternately and continuously providing circular arc columns 7d having a circular cross-sectional shape at the top portion of 8 and a curved surface 9d connected to the ridge 8.

  Further, the ridge shown in FIG. 5 includes a substantially triangular prism 7a in which a cross-sectional shape of a top portion of the ridge 8 is triangular and a surface 9 connected to the ridge 8 is a straight line in a cross section viewed from the incident end surface portion 3 side. 8 are formed by alternately and continuously providing circular arc columns 7d having a circular cross-sectional shape at the top portion of 8 and a curved surface 9b connected to the ridge 8.

  Further, the ridge shown in FIG. 6 includes a substantially triangular prism 7b in which the cross-sectional shape of the top portion of the ridge 8 is triangular and the surface 9 connected to the ridge 8 is a straight line in the cross section viewed from the incident end surface 3 side, 8 is formed by alternately and continuously providing substantially triangular prisms 7c in which the cross-sectional shape of the apex portion 8 is an arc shape and the surface 9 connected to the ridge 8 is a straight line.

  Further, the ridge shown in FIG. 7 includes a substantially triangular prism 7a in which a cross-sectional shape of a top portion of the ridge 8 is a triangle and a surface 9 connected to the ridge 8 is a straight line in a cross section viewed from the incident end surface portion 3 side. The cross-sectional shape of the top portion of 8 is an arc shape, and a circular arc column 7d having a curved surface 9d connected to the ridge 8 is discontinuously provided on the back surface portion 5 at predetermined intervals. The portion of the back surface portion 5 where the 7a and the circular arc column 7d do not exist forms a mirror surface.

Here, the surfaces 9 and 9b connected to the ridge 8 are shown in FIGS.
In FIG. 8A, since the surface 9 connected to the ridge 8 such as the substantially triangular prism 7a, the approximately triangular prism 7b, or the approximately triangular prism 7c of the light guide plate 2 is a straight line, the light ray Lso1 traveling to the surface 9 has an incident angle with respect to the surface 9 The reflection angle is equally reflected and proceeds upward as a reflected light beam Lr1.
Similarly, the light ray Lso2 traveling to the surface 9 is reflected with the same incident angle and reflection angle with respect to the surface 9, and proceeds upward as a reflected light beam Lr2.
Furthermore, the light ray Lso3 that has traveled to the surface 9 is similarly reflected at the same incident angle and reflection angle with respect to the surface 9, and travels upward as a reflected light beam Lr3.

  In this way, the light ray Lso1, the light ray Lso2, and the light ray Lso3 are reflected in parallel and in the same direction by the straight surface 9 connected to the ridge 8 such as the substantially triangular prism 7a, the substantially triangular prism 7b, and the substantially triangular prism 7c, and the reflected light beam Lr1 and the reflected light beam. The light travels upward as Lr2 and reflected light beam Lr3. That is, when the surface 9 connected to the ridge 8 of the substantially triangular prism is a straight line, light is emitted at an emission angle in the same direction with respect to an incident angle from the same direction.

8B, since the surface 9b connected to the ridge 8 of the circular arc column 7d of the light guide plate 2 is a curve, the light ray Ls1 traveling to the surface 9b has a reflection angle equal to the incident angle formed with the normal of the surface 9b. And travels upward as a reflected light beam Lrr1.
Similarly, the light beam Ls2 traveling to the surface 9b is reflected at a reflection angle equal to the incident angle formed with the normal line of the surface 9b, and proceeds upward as a reflected light beam Lrr2.
Furthermore, the light beam Ls3 that has traveled to the surface 9b is also reflected at a reflection angle equal to the incident angle that is formed with the normal line of the surface 9b, and travels upward as a reflected light beam Lrr3.

  In this way, the surface 9b connected to the ridge 8 of the substantially triangular prism 7d reflects the light beam Ls1, the light beam Ls2, and the light beam Ls3 in different directions depending on the curve, and proceeds upward as the reflected light beam Lrr1, the reflected light beam Lrr2, and the reflected light beam Lrr3. That is, when the surface 9b connected to the ridge 8 of the substantially triangular prism is a curve, the normal line always changes, and therefore, the emission angles are all emitted at different emission angles. Therefore, the emission angle can be controlled by controlling the curvature of the curve of the surface 9b connected to the ridge 8 in accordance with the purpose.

In addition, since the cross-sectional shape of the top portion of the ridge 8 of the light guide plate 2 is a triangle shape or an arc shape, there is no great optical difference, but although not shown mechanically, an optical component provided above the surface portion 4 In addition, the contact area with respect to the reflection sheet 12 or the like provided below the back surface portion 5 is smaller when the cross-sectional shape of the top portion of the ridge 8 is triangular.
Further, although depending on the material of the light guide plate 2 and the like, the change in wear of the contact portion over time is smaller when the cross-sectional shape of the top portion of the ridge 8 is an arc shape.
Therefore, the optical member provided above the front surface portion 4, the reflective sheet 12 provided below the back surface portion 5, and the optical component provided above the front surface portion 4 corresponding to the material of the light guide plate 2 and below the back surface portion 5. Can be prevented from sticking to the front surface portion 4 or the back surface portion 5 with respect to the reflection sheet 12 or the like provided in FIG.

As described above, the substantially triangular prism 7a, the substantially triangular prism 7b, and the incident end face 3 side where the cross-sectional shape of the apex of the ridge 8 of the cross section from the incident end face 3 side is triangular and the surface 9 connected to the ridge 8 is a straight line. The cross-sectional shape of the top portion of the ridge 8 of the cross section from the side of the substantially triangular prism 7c in which the cross-sectional shape of the top portion of the ridge 8 is arc-shaped and the surface 9 connected to the ridge 8 is a straight line A portion of the back surface portion 5 where the surface 9b connected to the ridge 8 in the shape of the arc column 7d and the like may be variously combined. May be provided with a mirror surface.
In the description here, the substantially triangular prisms 7 a, 7 b, 7 c, the circular arc column 7 d, etc. are provided on the back surface portion 5, but they may be provided on the front surface portion 4, or both surfaces of the front surface portion 4 and the back surface portion 5. May be provided.

In the light guide plate 2, the light incident from the incident end face portion 3 travels into the light guide plate 2 in a range where the refraction angle γ satisfies the expression 0 ≦ | γ | ≦ Sin ⁻¹ (1 / n). For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 2, is about n = 1.49, the incident light is in the range of the refraction angle γ = ± 42 °.

  Further, the light incident on the light guide plate 2 within the range of the refraction angle γ = ± 42 ° is Sin α = (1 / n) at the boundary surface between the light guide plate 2 and the air layer (refractive index is n = 1). The critical angle can be expressed by the following formula. For example, since the refractive index of acrylic resin, which is a resin material used for the general light guide plate 2, is about n = 1.49, the critical angle α is about α = 42 °.

Therefore, when the rear face 5 of the light guide plate 2 does not have the substantially triangular prism 7a or the substantially triangular prism 7b, the incident light refracted from the incident end face 3 toward the rear face 5 is flat as described above. In the case of a mirror surface portion), the light is totally reflected in the direction of the surface portion 4 at the same reflection angle as the incident angle, and is refracted by the light deflecting element 14 provided on the surface portion 4 and emitted to the outside.
Further, since the entire light guide plate 2 has a wedge shape, when the reflection angle is deflected at the back surface portion 5 and reaches the surface portion 4, the incident angle becomes an angle that breaks the critical angle. Taper leak).

  Although the above-described action only in the vertical direction of the back surface portion 5 and the front surface portion 4 of the light guide plate 2 works, the light guide plate 2 has a substantially triangular prism 7a and a substantially triangular prism 7b on the back surface portion 5 as shown in FIG. Therefore, the incident light refracted from the incident end face part 3 toward the back face part 5 is reflected in the direction of the side face part 6 in addition to the action in the vertical direction by the surface 9 of the substantially triangular prism 7a or the substantially triangular prism 7b. The outgoing light from the portion 4 spreads in the direction of the side surface portion 6 and the incident angle with respect to the surface portion 4 is small. For this reason, the emitted light from the surface portion 4 can be emitted in a direction perpendicular to the surface portion 4.

  FIG. 9A is a diagram of a substantially triangular prism 7 a portion provided on the back surface portion 5, and incident light Lo refracted from the incident end surface portion 3 toward the back surface portion 5 is a straight surface 9 connected to the ridge 8. The light is reflected obliquely upward and proceeds in the direction of the surface portion 4 as reflected light Lro.

  Similarly, FIG. 9B is a diagram in which a substantially triangular prism 7a is continuously provided on the back surface portion 5. The incident light refracted from various directions of the incident end surface portion 3 toward the back surface portion 5 in the left direction. Incident light Lo1 is reflected in the slightly upper direction of the other left-side straight surface 9 facing the straight surface 9 connected to the right side of the ridge 8, and this reflected light beam L2R is another straight-surface 9 Then, the light is further reflected obliquely upward by the surface 9 and proceeds to the right in the direction of the surface portion 4 as reflected light L1o.

Similarly, the incident light Lo2 is reflected obliquely upward by the straight surface 9 connected to the right side of the ridge 8, and proceeds to the left in the direction of the surface portion 4 as the reflected light L2o.
Similarly, the incident light Lo3 from the right direction is reflected obliquely upward at the ridge 8 and proceeds to the left in the direction of the surface portion 4 as reflected light L3o.

In this example, in the light guide plate 2, when the substantially triangular prisms 7 a, 7 b, 7 c and the circular arc column 7 d are continuously provided, the adjacent distance between the ridge 8 and the ridge 8 is in the range of 30 to 150 microns. Therefore, the ridges 8 having different heights can be obtained by changing the adjacent interval between the ridges 8.
For example, when a liquid crystal display device (not shown) is placed above the light guide plate 2, the pitch of the liquid crystal pixels of the liquid crystal display device and the substantially triangular columns 7a, 7b, 7c and the arc column 7d provided on the light guide plate 2 It is possible to select the pitches so as not to coincide with each other, and therefore it is possible to prevent the occurrence of moire.

Further, in the light guide plate 2, the intervals between the different heights of the ridges 8 in which the substantially triangular prisms 7a, 7b, 7c and the circular arc column 7d are provided continuously or discontinuously are in the range of 1 to 10 microns.
In this manner, since the height of the ridge 8 is different even if the apex angle of the ridge 8 is optically the same, the spread range of the emitted light with respect to the incident angle of the substantially triangular columns 7a, 7b, 7c and the circular column 7d under the same conditions. Since the pitches and ridge heights of the substantially triangular prisms 7a, 7b, and 7c and the circular arc column 7d are different, different amounts of emitted light can be obtained.
Therefore, uniform and high-intensity outgoing light can be obtained by controlling the spreading range of the outgoing light and the amount of outgoing light according to the purpose.

  Further, since the heights of the substantially triangular prisms 7a, 7b, 7c and the circular arc column 7d are not constant (equivalent), the optical component provided above the front surface portion 4 and the reflection sheet 12 provided below the back surface portion 5 are guided. It can prevent sticking to the front surface part 4 and the back surface part 5 of the optical plate 2.

  For this reason, it is possible to prevent the optical action from being hindered, such as changing the deflection direction of the target light or locally generating more light (bright lines) than necessary.

The light source 10 includes a cold cathode fluorescent lamp (CCFL) or a semiconductor light emitting element (such as an LED or a laser).
Cold cathode fluorescent lamps (CCFLs) are provided with electrodes on both ends of a thin quartz glass tube, etc., and are colored by a fluorescent material applied to the inside of the tube and applied to almost the entire wavelength range of color temperature including ultraviolet rays and RGB. It emits light in a cylindrical shape.
In addition, the semiconductor emitting element uses three primary colors of red light emission, green light emission, and blue light emission in a linear form (array form) such as a high-intensity light emitting element of a quaternary compound or a compound such as InGaAlP, InGaAlN, and InGaN. .

  Further, a light emission color mixed by a light emission color from a wavelength conversion material (YAG system) excited and emitted by light from the semiconductor light emitting element and a light emission color of the semiconductor light emitting element itself may be used. In this case, for example, a wavelength conversion material (YAG system) that is excited by light from a blue light emitting InGaAlN semiconductor light emitting element and emits yellow or orange light is provided around the semiconductor light emitting element, and the blue color of the semiconductor light emitting element itself is provided. It is possible to obtain a white emission color mixed by the emission color and the emission color such as yellow or orange from the wavelength conversion material.

  The reflector 11 is composed of a sheet metal or thermoplastic resin mixed with a white material such as titanium oxide, or a sheet of thermoplastic resin subjected to metal vapor deposition such as aluminum, or laminated metal foil. It surrounds the light source 10 provided in the vicinity of the incident end face 3 of the light plate 2 except for facing the incident end face 3 of the light guide plate 2.

  In addition, the reflector 11 has an uneven shape or a prism shape on the reflection surface, and the reflected light from the reflector 11 is made to be scattered light, so that the portion where the luminance is reduced near the electrode of the light source 10 is corrected, and the reflected light is uniform. Then, most of the light emitted from the light source 10 is directed to the incident end face 3 of the light guide plate 2.

The reflector 12 is made by press-molding a thin metal plate with excellent reflectivity such as aluminum or stainless steel.
Further, it is made by injection molding a thermoplastic resin mixed with a white material such as titanium oxide, or by depositing metal such as aluminum on the thermoplastic resin, or by laminating a metal foil.

  The reflector 12 is provided below the back surface portion 5 of the light guide plate 2, and leaks light from the light guide plate 2 and the light source 10 back to the light guide plate 2 again.

  The case 13 is made of an insulating resin material such as a thin metal plate having excellent reflectivity such as aluminum or stainless steel, a modified polyamide, polybutylene terephthalate, nylon 46, an aromatic polyester, or the like, and has a light reflectivity. In order to improve the light-shielding property, white powder such as titanium oxide is mixed into a shape having an upper opening by heat injection molding.

  Further, the case 13 may be directly used by omitting the reflector 12 when the reflector 12 is placed on the bottom or made of a thin metal plate having excellent reflectivity.

  FIG. 10 shows another example of the flat illumination device 1 of this example. In the flat illumination device 1 (1B) shown in FIG. 10, the opposite end faces of the light guide plate 2 (2B) are the incident end face portions 3, and the height of the ridge 8 is the same as that shown in FIG. A substantially triangular prism 7a or a substantially triangular prism 7b is provided on the back surface portion 5, the light guide plate 2 (2B) having a constant thickness, light sources 10a and 10b provided near the incident end surface portions 3 at both ends of the light guide plate 2B, and light sources 10a, Reflectors 11a and 11b surrounding 10b other than the portion facing the incident end surface portion 3 of the light guide plate 2B, the reflector 12 provided near the back surface portion 5, the light sources 10a and 10b, the light guide plate 2B, and the reflectors 11a and 11b. And the reflector 12 at least.

  Similarly to the description of FIG. 1, the back surface 5 and / or the front surface portion 4 are provided with convex stripes by a substantially triangular prism 7a, a substantially triangular prism 7b, a substantially triangular prism 7c, and an arcuate column 7d as shown in FIGS. They can be arranged continuously or discontinuously along the side surface portion 6 in a direction substantially perpendicular to the incident end surface portion 3. At that time, the cross-sectional shape of the top portion of the ridge may be a triangle shape or an arc shape. Further, the surface 9 connected to the ridge may be a straight line or a curved line. Further, in the light guide plate 2B, when the substantially triangular prisms 7a, 7b, 7c and the circular arc column 7d are continuously provided, the adjacent interval between the ridge 8 and the ridge 8 is in the range of 30 to 150 microns.

In addition, since an effect | action and an effect are the same as FIG. 1 demonstrated here, description is abbreviate | omitted.
However, since the light guide plate 2B in FIG. 10 has a constant thickness, the taper leak hardly occurs, and the light reaching the surface portion 4 is emitted to the outside by the light deflection element 14 provided on the surface portion 4. Can do.

  As described above, the flat illumination device of the present invention includes a light source, a light guide plate, a reflector that surrounds the light source except for a portion facing the incident end surface portion, a reflector provided near the back surface portion, and these light sources. And a case for housing the light guide plate, the reflector, and the reflector. The light guide plate includes an incident end surface portion that guides light, a surface portion that emits light guided from the incident end surface portion to the outside, a back surface portion that is located on the opposite side of the front surface portion, and the front surface portion and the back surface portion. It consists of a side part connected to the end face part, and is configured by arranging substantially triangular pillars or arc pillars having ridges with different heights extending in the direction substantially perpendicular to the incident end face part on the front face part and back face part in the side face direction. As a result, since the height of the light guide plate is optically different even if the apex angles of the ridges are equal, the spread range of the emitted light differs with respect to the incident angle under the same conditions of the substantially triangular prism or arc column, and the approximately triangular prism or arc column. Since the pitch and the height of the ridges are different, different emitted light amounts can be obtained. Further, since the height of the substantially triangular column or the arc column is not mechanically constant (equivalent), the optical member provided above the surface portion, the reflection sheet provided below the back surface portion, etc. It can prevent sticking to a part. Therefore, uniform and high-brightness outgoing light can be obtained by controlling the range of outgoing light and the amount of outgoing light according to the purpose, and the target light deflection direction can be changed or locally required. It can prevent optical effects such as the generation of the above light (bright lines), and there is no wear on the edges of the triangular or arc column, especially when used for many years. It is a flat illumination device that can obtain incident light and can obtain a stable and high luminance with a long life.

Suitable for backlights for small mobile products to backlights for large liquid crystal display devices, etc. Not only has high brightness but also an optical member provided above the surface part of a particularly large backlight and provided below the back part In addition, it is possible to prevent the reflection sheet or the like from sticking to the front surface portion or the back surface portion of the light guide plate and to prevent the optical action from being inhibited locally, such as generation of light (bright lines) more than necessary, In particular, when used for a long time, there is no wear on the ridges of the substantially triangular column or the arc column, and it is possible to obtain a high-luminance outgoing light free from spots over a long period of time.
However, it is possible to provide a light guide plate and a flat illumination device that can obtain stable and high-luminance outgoing light having a long life.

It is a schematic perspective view which shows an example of the plane illuminating device which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is a schematic sectional drawing of the light-guide plate which concerns on this invention. It is an approximate locus figure of light of a light guide plate concerning the present invention. It is an approximate locus figure of light of a light guide plate concerning the present invention. It is a schematic perspective view which shows the other example of the planar illuminating device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (1A, 1B) Planar illumination apparatus 2 (2A, 2B) Light guide plate 3 Incident end surface part 4 Surface part 5 Back surface part 6 Side part 7a, 7b, 7c Substantially triangular pillar 7d Arc pillar 8 Edge 9, 9b Surface 10a, 10b Light source 11a, 11b Reflector 12 Reflector 13 Case 14 Optical deflection element α Critical angle γ Refraction angle n Refractive index Lo1, Lo2, Lo3, L1o, L2o, L3o, Lo, Lro, L2R, Ls1, Ls2, Ls3, Lr1, Lr2, Lr3, Lrr1, Lrr2, Lrr3. Lso1, Lso2, Lso3 rays

Claims (6)

An incident end face part that guides light, a surface part that emits light guided from the incident end face part to the outside, a back face part that is located on the opposite side of the front face part, the front face part, the back face part, and the incident end face In the light guide plate consisting of side parts connected to the parts,
A plurality of substantially triangular prisms and / or circular arc columns having ridges with different heights extending in a direction substantially perpendicular to the incident end surface portion are arranged in the side surface direction with regularity on the front surface portion and / or the back surface portion. A light guide plate characterized by that. The light guide plate according to claim 1, wherein a cross-sectional shape of a top portion of the ridge is a triangle shape and / or an arc shape. The light guide plate according to claim 1, wherein the substantially triangular prism has a straight or curved surface connected to the ridge. The light guide plate according to claim 1, wherein the ridges have an adjacent interval in a range of 30 to 150 microns. The light guide plate according to claim 1, wherein the ridges have different height intervals ranging from 1 micron to 10 microns. A light source;
An incident end face portion that guides light from the light source, a surface portion that emits light guided from the incident end face portion to the outside, a back surface portion that is located on the opposite side of the surface portion, and the front surface portion and the back surface portion. And a side surface portion connected to the incident end surface portion, and the front surface portion and / or the back surface portion has a substantially triangular prism having ridges with different heights extending in a direction substantially perpendicular to the incident end surface portion or / and A light guide plate in which a plurality of arc pillars are arranged with regularity in the lateral direction;
A reflector that surrounds the light source other than a portion facing the incident end surface of the light guide plate;
A reflector provided in the vicinity of the back surface;
A flat illumination device comprising: a case for housing at least the light source, the light guide plate, the reflector, and the reflector.

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