JP2006004877A - Light guide plate, and flat illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate having a constant directivity (regularity) capable of almost vertically emitting light from a surface part with high brightness, and a flat illumination device using the same. <P>SOLUTION: The light guide plate is formed into such a shape that the light travelling from an incident side face part 3 toward a reflection side face part 4 does not generate taper leak, and provided with such a reflection face that makes the reflection side face 4 reflects the light in a direction of the incident side face part 3 which is different from the incident direction of the light from a light source 8 and a light source direction. A reflection pattern 10, not making the incident light from the incident side face part 3 reflects toward the incident side face part 3 and a surface part 6, but reflecting only the reflection light from the reflection side face part 4, is arranged on a back face part 7. By the above, the light from the light source 8 can be distributed to a part of the incident side face part 3 not facing the light source, to both end parts of the incident side face part 3 not facing the light source 8, and to the neighboring area thereof, to obtain a uniform light emission from a light emission face (surface part). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has a shape in which light from a light source is incident from an incident end face, spreads by an arbitrary refraction angle, and travels to the reflective end face does not cause a taper leak, and the reflective end face has at least one side surface. An incident end face having a circular arc shape spreading in the direction of the head and / or an arc shape spreading in the thickness direction of the front surface portion and the back surface portion, and the light reflected by the reflective end face portion is different from the incident light direction from the light source and the light source direction Reflection that reflects only the reflected light from the reflection end surface, and does not reflect the incident light from the incident end surface to the incident end surface and the front surface, and reflects to the back surface substantially at right angles to the direction and the incident end surface. A light guide plate that has a pattern and that emits light from the surface portion is not directed to any direction (does not spread) and can be emitted substantially vertically in a state of the shape of the surface portion, and the light guide plate is used Flat lighting Apparatus on.

  As a conventional light guide plate, the light guide plate is wedge-shaped so that light from the light source is incident from the incident end surface portion and light traveling to the reflection end surface portion on the opposite side facing the incident end surface portion causes a taper leak, Further, a method is known in which light reaching the reflection end face is reflected again in the direction of the incident end face, and light in both directions of light traveling from the light source and reflected light is used.

  Further, as a conventional light guide plate, there is also known a light guide plate in which the reflection surface of the reflection pattern is always arranged in the light source direction on the front surface portion and the back surface portion.

Furthermore, as a conventional flat light emitting device, a light source is provided in the center of the incident end face part of the light guide plate or in an array shape, and a reflective pattern whose reflective surface always faces the light source direction with respect to these light sources is provided on the front surface part and the back surface part. What consists of the provided light-guide plate etc. is known.
JP 2003-337333 A

  As the conventional light guide plate described above, the light guide plate is wedge-shaped so that light from the light source is incident from the incident end face portion and light traveling to the reflection end face portion at the opposite side facing the incident end face portion causes a taper leak. In addition, the light that has reached the reflection end face is reflected again in the direction of the incident end face, and the light that travels from the light source and the reflected light is used in both directions. That is, the emitted light has a large spread, such as the end face direction and the reflective end face direction. For example, if the pixels of the liquid crystal display device are not enlarged, a high-luminance color image cannot be obtained. For this reason, since the pixels are large, there is a problem that it is difficult to obtain a high-density, clear image with a small absolute pixel amount. .

  Moreover, as a conventional light guide plate, an object in which the reflection surface of the reflection pattern is always placed in the light source direction on the front surface portion or the back surface portion, the emitted light is always offset in the light source direction, and the direction opposite to the light source Observing from the viewpoint, the luminance is lowered, and there is a problem that when used in a liquid crystal display device, the viewing direction is shifted.

  Further, in the conventional flat light emitting device, the light source is provided in the center of the incident end face portion of the light guide plate or in an array shape, and a reflective pattern whose reflective surface is always directed to the light source direction is provided on the front surface portion and the back surface portion. The light emitted from the light source plate is always shifted toward the light source, and when viewed from the opposite direction to the light source, the luminance is reduced. There is a problem.

  In addition, when the light sources are arranged in an array, the emitted light is emitted as a whole, and when used in a liquid crystal display device, a high-luminance color image can be obtained unless the pixels are enlarged. Therefore, since the pixels are large, there is a problem that it is difficult to obtain a high-definition image with a small absolute pixel amount and a high density.

  An object of the present invention is to form a shape that does not directly emit light (taper leakage) from an incident end surface portion that guides light from a light source to a light guide plate to a reflective end surface portion that is opposite to the incident end surface portion. The light that reflects at the reflection end face and travels to the incident end face is used, but is not simply reflected at the reflection end face, but, for example, the theory that collects radio waves parallel to the axis at one point by a reflector having a paraboloid Equivalently, light that travels from a single light source with a spread (cone-shaped light refracted at the incident end face) is reflected by the reflecting end face, which is a reflecting mirror, and reflected substantially at right angles to the incident end face. Reflection pattern that reflects only the reflected light in the direction of the surface portion so that only the reflected light is encountered at this time (the inclination and the light encountered so that the light from the incident end face toward the reflecting end face is not encountered) The pattern that transmits) A light guide plate that is provided alone or continuously on the surface portion, and the light emitted from the surface portion has a constant directivity (regularity) and can be emitted substantially vertically from the surface portion with high brightness, and planar illumination using this light guide plate To provide an apparatus.

  The light guide plate according to claim 1 of the present invention has a shape in which light traveling from the incident end surface portion to the reflecting end surface portion does not cause a taper leak, and the reflecting end surface portion is different from the incident light direction from the light source and the light source direction. It has a reflective surface that reflects in the direction of the part.

  The light guide plate according to claim 1 has a shape in which light traveling from the incident end surface portion to the reflective end surface portion does not cause a taper leak, and the reflective end surface portion is in the incident end surface direction different from the incident light direction from the light source and the light source direction. Since it has a reflecting surface that reflects, light from the light source can be present in a portion where the light source does not exist at the incident end surface, at both ends of the incident end surface, and in the vicinity thereof.

  The light guide plate according to claim 2 is characterized in that the reflected light that is incident from the light source, spreads by an arbitrary refraction angle, proceeds to the reflection end surface, and is reflected by the reflection end surface is substantially perpendicular to the incident end surface. And

  The light guide plate according to claim 2 is incident from the light source, spreads by an arbitrary refraction angle, proceeds to the reflection end surface portion and is reflected by the reflection end surface portion, and is substantially perpendicular to the incident end surface portion. Uniform and unidirectional emission light can be obtained by directing the reflection pattern or the like on the surface portion in a single direction.

  Further, the light guide plate according to claim 3 has a reflection pattern on the back surface portion that does not reflect the incident light from the incident end surface portion toward the incident end surface portion and the surface portion, but reflects only the reflected light from the reflection end surface portion. It is characterized by.

  The light guide plate according to claim 3 has a reflection pattern in which the incident light from the incident end surface portion does not reflect in the direction of the incident end surface portion and the front surface portion but reflects only the reflected light from the reflection end surface portion on the back surface portion. High-luminance light that is substantially perpendicular to the surface portion can be emitted by a uniform, unidirectional reflection pattern at a portion where the light source does not exist at the end surface portion, at both ends of the incident end surface portion, and in the vicinity thereof.

  The light guide plate according to claim 4 is characterized in that the reflection pattern is single or / and continuous, and the pitch of the reflection pattern is uniform or gradation in the direction of the incident end face part and the reflective end face part.

  In the light guide plate according to the fourth aspect, the reflection pattern is single or / and continuous, and the pitch of the reflection pattern is uniform or gradation in the direction of the incident end face part and the reflection end face part. Can be emitted.

  Furthermore, the light guide plate according to claim 5 is characterized in that the reflection end surface portion has an arc shape extending in the direction of at least one side surface portion or / and an arc shape extending in the thickness direction of the front surface portion and the back surface portion. To do.

  The light guide plate according to claim 5 has an arc shape in which the reflection end surface portion extends in the direction of at least one side surface portion and / or an arc shape in the thickness direction between the front surface portion and the back surface portion, so that the incident of the light guide plate Light that has been incident from the end face is spread by an arbitrary refraction angle and is propagated to the reflection end face, and the light that has been spread in the direction of both side faces is directed to any position direction of the incident end face and the incident end face. It can be reflected at a substantially right angle. Moreover, by providing an arc shape that spreads in the direction of the side surface according to the number of light sources, it can be reflected more effectively at an arbitrary position direction in the direction of the incident end face and the incident end face.

  Further, the light spread and advanced in the direction of the front surface portion and the back surface portion can be reflected substantially at right angles to the back surface direction in the direction of the incident end surface portion, the arbitrary position direction in the front surface direction, the back surface portion, and the front surface portion. In addition, by providing an arc shape that spreads in the thickness direction between the front surface portion and the back surface portion according to the thickness of the light guide plate, the position of the back surface portion in the direction of the incident end surface portion or an arbitrary position direction in the surface portion direction is more effective. And can be reflected with respect to the back surface portion and the front surface portion direction.

  The light guide plate according to claim 6 is characterized in that the side surface portion connects the incident end surface portion and the reflection end surface portion nonlinearly.

  In the light guide plate according to the sixth aspect, the side surface portion nonlinearly connects the incident end surface portion and the reflection end surface portion. Therefore, the light reaching the side surface portion from the light source directed from the incident end surface portion to the reflection end surface portion. As much as possible, it can be advanced to the reflection end face portion, and it can be prevented that the parallel reflected light from the reflection end face portion becomes a bright line when reaching the straight side face portion.

Furthermore, the flat illumination device according to claim 7 includes at least one light source,
An incident end face portion that is located in the vicinity of the light source and guides light from the light source, a reflection end face portion that reflects light that travels straight from the incident end face portion and faces the incident end face portion, a surface portion that emits light, and a surface portion It consists of the opposite back surface part, and the incident end face part, the reflective end face part, the surface part and the side part in contact with the back face part, and the light traveling from the incident end face part to the reflective end face part has a shape that does not cause a taper leak and is reflected. A light guide plate having a reflection surface such that the end surface portion reflects in the direction of incident light from the light source and the direction of the incident end surface different from the light source direction;
And a reflector provided at a lower portion of the back surface of the light guide plate.

The flat illumination device according to claim 7 includes at least one light source,
An incident end face portion that is located in the vicinity of the light source and guides light from the light source, a reflection end face portion that reflects light that travels straight from the incident end face portion and faces the incident end face portion, a surface portion that emits light, and a surface portion It consists of the opposite back surface part, and the incident end face part, the reflective end face part, the surface part and the side part in contact with the back face part, and the light traveling from the incident end face part to the reflective end face part has a shape that does not cause a taper leak and is reflected. A light guide plate having a reflection surface such that the end surface portion reflects in the direction of incident light from the light source and the direction of the incident end surface different from the light source direction;
And a reflector provided at the lower part of the rear surface of the light guide plate, so that the light incident from the incident end surface portion of the light guide plate is spread at an arbitrary refraction angle and proceeds to the reflective end surface portion in the direction of both side surfaces. The spread and advanced light can be reflected at an arbitrary position in the direction of the incident end face part and at a substantially right angle with respect to the incident end face part. In addition, by providing an arc shape that spreads in the direction of the side surface according to the number of light sources, it is more effectively reflected at an arbitrary position direction in the direction of the incident end face and at substantially right angles with respect to the incident end face, and substantially from the surface portion. Vertical light can be emitted.

  The light guide plate according to claim 1 has a shape in which light traveling from the incident end surface portion to the reflective end surface portion does not cause a taper leak, and the reflective end surface portion is in the incident end surface direction different from the incident light direction from the light source and the light source direction. Since it has a reflecting surface that reflects, light from the light source can be present in a portion where the light source does not exist at the incident end surface, at both ends of the incident end surface, and in the vicinity thereof. For this reason, uniform emitted light can be obtained from the emission surface (surface portion).

  The light guide plate according to claim 2 is incident from the light source, spreads by an arbitrary refraction angle, proceeds to the reflection end surface portion and is reflected by the reflection end surface portion, and is substantially perpendicular to the incident end surface portion. Uniform and unidirectional emission light can be obtained by directing the reflection pattern or the like on the surface portion in a single direction. Thereby, the light from the light source can be emitted with high brightness without waste.

  The light guide plate according to claim 3 has a reflection pattern in which the incident light from the incident end surface portion does not reflect in the direction of the incident end surface portion and the front surface portion but reflects only the reflected light from the reflection end surface portion on the back surface portion. High-luminance light that is substantially perpendicular to the surface portion can be emitted by a uniform, unidirectional reflection pattern at a portion where no light source exists at the end surface portion, at both ends of the incident end surface portion, and in the vicinity thereof. As a result, the emitted light rises from the surface portion without changing the shape of the light guide plate. For example, a high-luminance color image can be obtained even if the pixels of the liquid crystal display device are small. Moreover, a high-density, clear image can be obtained by reducing the pixels and increasing the absolute pixel amount.

  In the light guide plate according to the fourth aspect, the reflection pattern is single or / and continuous, and the pitch of the reflection pattern is uniform or gradation in the direction of the incident end face part and the reflection end face part. Can be emitted. As a result, the emitted light rises from the surface portion without changing the shape of the light guide plate. For example, a high-luminance color image can be obtained even if the pixels of the liquid crystal display device are small. Moreover, a high-density, clear image can be obtained by reducing the pixels and increasing the absolute pixel amount.

  The light guide plate according to claim 5 has an arc shape in which the reflection end surface portion extends in the direction of at least one side surface portion and / or an arc shape in the thickness direction between the front surface portion and the back surface portion, so that the incident of the light guide plate Light that has been incident from the end face is spread by an arbitrary refraction angle and is propagated to the reflection end face, and the light that has been spread in the direction of both side faces is directed to any position direction of the incident end face and the incident end face. It can be reflected at a substantially right angle. Moreover, by providing an arc shape that spreads in the direction of the side surface according to the number of light sources, it can be reflected more effectively at an arbitrary position direction in the direction of the incident end face and the incident end face. For this reason, light having a constant directionality (regularity) can always be emitted as the emitted light.

  Further, the light spread and advanced in the direction of the front surface portion and the back surface portion can be reflected substantially at right angles to the back surface direction in the direction of the incident end surface portion, the arbitrary position direction in the front surface direction, the back surface portion, and the front surface portion. In addition, by providing an arc shape that spreads in the thickness direction between the front surface portion and the back surface portion according to the thickness of the light guide plate, the position of the back surface portion in the direction of the incident end surface portion or an arbitrary position direction in the surface portion direction is more effective. And can be reflected with respect to the back surface portion and the front surface portion direction. For this reason, it is possible to easily emit outgoing light from the front surface portion or the back surface portion, to easily encounter a reflection pattern provided on the front surface portion or the back surface portion, and to control the outgoing light from the front surface.

  In the light guide plate according to the sixth aspect, the side surface portion nonlinearly connects the incident end surface portion and the reflection end surface portion. Therefore, the light reaching the side surface portion from the light source directed from the incident end surface portion to the reflection end surface portion. Can be advanced to the reflection end face portion as much as possible, and it can be prevented that the parallel reflected light from the reflection end face portion becomes a bright line when reaching the straight side face portion, so that a good-looking outgoing light beam can be obtained. .

The flat illumination device according to claim 7 includes at least one light source,
An incident end face portion that is located in the vicinity of the light source and guides light from the light source, a reflection end face portion that reflects light that travels straight from the incident end face portion and faces the incident end face portion, a surface portion that emits light, and a surface portion It consists of the opposite back surface part, and the incident end face part, the reflective end face part, the surface part and the side part in contact with the back face part, and the light traveling from the incident end face part to the reflective end face part has a shape that does not cause a taper leak and is reflected. A light guide plate having a reflection surface such that the end surface portion reflects in the direction of incident light from the light source and the direction of the incident end surface different from the light source direction;
And a reflector provided at the lower part of the rear surface of the light guide plate, so that the light incident from the incident end surface portion of the light guide plate is spread at an arbitrary refraction angle and proceeds to the reflective end surface portion in the direction of both side surfaces. The spread and advanced light can be reflected at an arbitrary position in the direction of the incident end face part and at a substantially right angle with respect to the incident end face part. In addition, by providing an arc shape that spreads in the direction of the side surface according to the number of light sources, it is more effectively reflected at an arbitrary position direction in the direction of the incident end face and at substantially right angles with respect to the incident end face, and substantially from the surface portion. Vertical light can be emitted. Therefore, for example, even if the pixels of the liquid crystal display device are small, a high-luminance color image can be obtained, and a high-density, clear image can be obtained by reducing the pixels and increasing the absolute pixel amount.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The present invention provides an arc-shaped reflecting end face that is positioned opposite to the incident end face portion, even when the light from a small light source such as an LED enters the light guide plate at a refraction angle that is widened by refraction from the incident end face portion. The parallel light (light substantially perpendicular to the incident end face part) is reflected by the part in the direction of the incident end face part. Further, when traveling from the incident end face portion toward the reflecting end face portion, the light guide plate is totally reflected and the spread is reduced, and the spread is increased only when the reflection end face portion reflects. Then, the light is not emitted from the surface portion when proceeding from the incident end surface portion to the reflection end surface portion on the back surface corresponding to these lights, and is only emitted from the surface portion by total reflection when proceeding from the reflection end surface portion to the incident end surface portion. By providing the reflection pattern, light is reflected from the reflection end face portion to the position of the light guide plate where there is no LED or the like in the vicinity and is emitted by the reflection pattern to obtain high-luminance and uniform emission light from the entire light guide plate Provided are a light guide plate and a flat illumination device capable of

  FIG. 1 is a schematic perspective view of a flat illumination device according to the present invention, FIGS. 2 to 4 are schematic light trajectory diagrams in each form of the light guide plate according to the present invention, and FIGS. 5 to 8 are each of the light guide plates according to the present invention. FIG. 9 is a schematic light locus diagram of a light guide plate according to another embodiment of the present invention.

  As shown in FIG. 1, the flat illumination device 1 of this example is schematically configured by a light guide plate 2, a light source 8, and a reflector 9. In the example of FIG. 1, the reflector 9 is a case that has a reflective surface facing the side surface portion 5 and the back surface portion 7 of the light guide plate 2.

  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. As shown in FIG. 1, the light guide plate 2 includes an incident end surface portion 3 that guides light from the light source 8, a reflective end surface portion 4 that faces the incident end surface portion 3, a surface portion 6 that emits light, and the surface The back surface portion 7 is opposed to the portion 6, and the incident end surface portion 3, the reflection end surface portion 4, the front surface portion 6, and the side surface portion 5 in contact with the back surface portion 7.

In the light guide plate 2, the light incident from the incident end surface 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 a general light guide plate 2, is about n = 1.49, the light incident from the incident end surface portion 3 falls within the range of the refraction angle γ = ± 42 °. is there.

  In addition, the light incident into 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 an equation. 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 °.

  With respect to the above logic, the light guide plate 2 has such a shape that light traveling from the incident end face portion 3 to the reflecting end face portion 4 does not cause a taper leak.

  Specifically, for example, the shape of the reflective end face portion 4 is thicker than the thickness of the incident end face portion 3 (distance from the front surface portion 6 to the back surface portion 7) as shown in FIG. The light guide plate 2 has a shape in which the thickness and the thickness of the reflection end face portion 4 are equal. Furthermore, the light guide plate 2 of the present example is configured so that the reflection end face portion 4 has a direction of incident light from the light source 8 (a direction in which light spread at a refraction angle is returned) and a light source, as shown in FIGS. 2, 3, and 4. It has a reflecting surface 4 that reflects in the direction of the incident end face 3 different from the eight directions.

  The light guide plate 2 in the example of FIG. 2 has an arc shape in which the reflection end surface portion 4 extends in the direction of the side surface portion 5, and the arc shape is convex outward. In the arc-shaped reflection end face 4, the light Lo incident from the light source 8 into the light guide plate 2 with a refraction angle γ (for example, within a range of refraction angle γ = ± 42 °) is spread. The reflected light Lr travels substantially at right angles to the incident end face 3.

  This is the same as the theory of collecting radio waves parallel to the axis at one point by a reflector having a paraboloid, for example. (Cone-shaped light) is reflected by the reflecting end face portion 4 which is a reflecting mirror, and the reflected light Lr substantially perpendicular to the incident end face portion 3 is advanced.

  Similarly, as shown in FIG. 3, the light guide plate 2 can be configured such that the reflection end surface portion 4 has a plurality of arc shapes extending outward in the direction of the side surface portion 5 and is convex outward. In this case, the arc shape of the reflection end face portion 4 is formed corresponding to the number and position of the light sources 8. At the reflection end face portion 4, the light source 8 of each of the plurality of light sources 8 is incident on the light guide plate 2 with a refraction angle γ (for example, within a range of refraction angle γ = ± 42 °) with a spread. The light Lo is reflected by each convex arc-shaped reflecting surface corresponding to the light source 8, and each reflected light Lr travels substantially at right angles to the incident end face part 3.

  Further, as shown in FIG. 4, the light guide plate 2 has a configuration in which the reflection end surface portion 4 has a plurality of circular arc shapes (in contrast to FIGS. 2 and 3, the reflection end surface portion 4 is concave) extending in the direction of the side surface portion 5. be able to. In the reflection end face portion 4, light Lo incident from the light source 8 into the light guide plate 2 with a refraction angle γ (for example, within a range of refraction angle γ = ± 42 °) with a spread in the light guide plate 2 is formed into a concave arc shape. The reflected light Lr travels to a portion where the light source 8 of the incident end surface portion 3 does not exist, both end portions of the incident end surface portion 3 and the vicinity thereof.

  Thus, since the reflection end face 4 of the light guide plate 2 has an arc shape and extends in the direction of the side face 5, the light incident from the incident end face 3 of the light guide plate 2 can have an arbitrary refraction angle (depending on the material of the light guide plate 2). In the light which has been spread by the determination) and has traveled to the reflection end face part 4, the light which has spread and propagated in the direction of the both side face parts 5 can be moved by the arc-shaped reflection end face part 4 in any position direction or incident end face part in the direction of the incident end face part 3. 3 can be reflected at a substantially right angle.

  Furthermore, if an arc-shaped reflection end surface portion 4 that extends in the direction of the side surface portion 5 according to the number of the light sources 8 is provided, it is more effective for any position direction in the direction of the incident end surface portion 3 and the incident end surface portion 3. It can be reflected at right angles. Thereby, light with a constant directivity (regularity) can always be emitted as emitted light.

  In addition, as shown in FIG. 5, the light Lo that has entered the light guide plate 2 is exposed to the outside at an incident angle below the critical angle at the boundary surface (the front surface portion 6 and the back surface portion 7) between the light guide plate 2 and the air layer. In particular, the light guide plate 2 has a shape in which the thickness of the reflective end surface portion 4 is thicker than the thickness of the incident end surface portion 3 (distance from the front surface portion 6 to the back surface portion 7) (the thickness of the incident end surface portion 3). The same applies to the light guide plate 2 having the same thickness of the reflection end surface portion 4), and the reflection angle becomes larger with respect to the incident angle as it is totally reflected by the front surface portion 6 and the back surface portion 7 and proceeds to the reflection end surface portion 4. Incident angle increases (Lbr <Lfr).

  Furthermore, as shown in FIG. 6, the light guide plate 2 can be provided with a reflection end surface portion 4 that is convex outward in an arc shape that spreads in the thickness direction between the front surface portion 6 and the back surface portion 7.

  The reflection end surface portion 4 can be provided according to the thickness of the light guide plate 2, or can be provided by changing the number of convex arc shapes depending on the distance between the incident end surface portion 3 and the reflection end surface portion 4. .

  As a result, the light Lo that has traveled to the reflective end surface portion 4 is reflected by the convex arc-shaped reflective end surface portion 4, and the reflected light Lrb1 and the reflected light Lrb2 are likely to encounter the reflective pattern 10 provided on the back surface portion 7 and the like. To do.

  Further, by controlling the radius of curvature of the arc of the reflection end face 4 and the center position of the radius, the position where the reflected light Lrb1 and the reflected light Lrb reach the back surface 7 can be controlled. You can control the light.

  Further, as shown in FIG. 7, the light guide plate 2 does not reflect the incident light from the incident end surface portion 3 on the back surface portion 7 in the direction of the incident end surface portion 3 and the front surface portion 6, but only the reflected light from the reflective end surface portion 4. The reflective pattern 10 that reflects the light can be provided.

  For example, the reflection pattern 10 is provided with a wall 10a substantially perpendicular to the direction of the incident end face 3 and a cross section formed by an inclined face 10b connecting the wall 10a and the back face 7 is formed in a substantially right triangle shape. .

  Further, the reflection pattern 10 can be formed in a dot-like single shape or a continuous shape in which a cross section is connected to both side portions 5. In addition, the distribution of the reflection pattern 10 may change the pitch between the incident end surface portion 3 and the reflection end surface portion 4.

  Further, in the case of the reflection pattern 10 having a single shape, not only the pitch change but also the staggered shape between the side surface portions 5 may be used, or it may be distributed randomly.

  As described above, when the light beam Lo (even light having a large refraction angle at the incident end surface portion 3) that has entered from the incident end surface portion 3 proceeds to the inclined surface 10b of the reflective pattern 10, the reflective pattern 10 has an inclined surface 10b. The reflected light Lpr has a larger reflection angle than that when the inclined surface 10b of the reflection pattern 10 is not provided, and travels in the direction of the reflection end surface portion 4 in a substantially parallel manner.

  Further, when the light beam Lo1 incident from the incident end face portion 3 travels to the wall 10a of the reflection pattern 10, the incident angle is small because the wall 10a is substantially vertical, so that the light is transmitted through the wall 10a and transmitted through the wall 10a. The light is emitted as transmitted light Loo to the outside of the back surface portion 4. However, although not described here, the light emitted by the reflector 9 is returned to the light guide plate 2 below the light guide plate 2 again.

  Furthermore, since the reflection pattern 10 has the same inclination direction as the light Lo2 refracted at the incident end face 3 (in this case, the light refracted in the direction of the back surface 7), the reflection pattern 10 deviates from the reflection pattern 10 and the back surface 7 Is reflected and travels in the direction of the reflection end face 4 as reflected light Lfr.

  Further, as shown in FIG. 8, the light Lr reflected by the reflection end face portion 4 is totally reflected by the inclined surface 10 b of the reflection pattern 10 and is emitted from the surface portion 6 as emitted light Lfo.

  In this way, the light traveling from the incident end surface portion 3 toward the reflecting end surface portion 4 reaches the reflecting end surface portion 4 while reducing the spread of the light that is refracted and spread at the incident end surface portion 3. Then, the light reflected by the reflection end face portion 4 travels in the direction of the incident end face portion 3 as light having a spread, and is totally reflected by the reflection pattern 10 during that time and emitted outside the light guide plate 2.

  Further, by directing these reflection patterns 10 in a single direction, uniform and unidirectional emission light can be obtained, and light from the light source 8 can be uniformly and highly radiated from the emission surface (surface portion 6) without waste. Can be emitted.

  Further, as shown in FIG. 9, in the light guide plate 2, the side surface portion 5 in FIG. 2 is a side surface portion 5 b that connects the incident end surface portion 3 and the reflection end surface portion 4 with a non-linear arc having a predetermined curvature. .

  More specifically, in the example of FIG. 9, the light guide plate 2 having a substantially drum shape in which the reflection end surface portion 4 has a convex arc shape and the side surface portion 5 b has a convex arc shape is configured. According to this configuration, the side surface portion such as the reflected light Lsr in which the light Lo reaching the side surface portion 5b in the light Lo having a spread from the light source 8 directed from the incident end surface portion 3 toward the reflection end surface portion 4 is totally reflected by the side surface portion 5b. As much light that has reached 5b can be advanced to the reflection end face portion 4 as much as possible. In addition, it is possible to prevent the parallel reflected light Lr from the reflection end face part 4 from becoming a bright line when it reaches the straight side face part 5, and an outgoing light beam having a good appearance can be obtained.

  The light source 8 is composed of a semiconductor light emitting element that emits high brightness, such as a semiconductor chip of a compound such as a quaternary compound or an InGaAlP, InGaAlN, or InGaN compound. The light source 8 arranges three monochromatic lights of the red light emitting semiconductor light emitting element (R), the green light emitting semiconductor light emitting element (G), and the blue light emitting semiconductor light emitting element (B) in one light source 8 to obtain white light as the light source 8. The light is emitted from the opening.

  The light source 8 is excited by the semiconductor light emitting element and the light emitted from the semiconductor light emitting element, and emits a wavelength different from the wavelength of the base semiconductor light emitting element (generally emitting a wavelength longer than the base wavelength). Depending on the wavelength conversion material, white light may be emitted by the emission color of the base semiconductor light emitting element and the emission color of the wavelength conversion material. For example, it is excited by a blue light emitting semiconductor light emitting element and the blue light emitting semiconductor light emitting element, and can emit white light by mixing a yellow light emitting color and a blue light emitting color by a yellow light emitting fluorescent material.

  The reflector 9 is made of a resin in which a white material such as titanium oxide is mixed into a thermoplastic resin or a metal such as aluminum deposited on a thermoplastic resin or a metal foil laminated or a metal. The reflector 9 has a reflective surface facing the side surface portion 5 and the back surface portion 7 of the light guide plate 2, and serves to reflect the leaked light from the light guide plate 2 and return it to the light guide plate 2 again.

  As described above, the light guide plate 2 is incident from the incident end surface portion 3 by the light guide plate 2 having a uniform thickness such that the thickness of the light guide plate 2 increases as the light guide plate 2 moves from the incident end surface portion 3 toward the reflection end surface portion 4. The transmitted light travels from the light guide plate 2 toward the reflection end face portion 4 without causing a taper leak. In particular, when the thickness of the light guide plate 2 increases toward the reflection end face part 4, while the light having a spread due to refraction is totally reflected by the front face part 6 and the back face part 7, these front face part 6 and back face part The incident angle with respect to 7 becomes larger and the spread of light becomes narrower. As a result, the reflected light reflected by the reflection end face part 4 gradually decreases in incident angle with respect to the front face part 6 and the back face part 7 toward the incident end face part 3, and widens the light and easily leaks taper. It becomes a state.

  With such a state, the reflection end face part 4 of the light guide plate 2 is formed in an arc shape (both side face part direction and thickness direction). Thereby, the light which is refracted and spreads at the incident end face part 3 travels in the direction of the reflecting end face part 4. Then, the light directed toward the both side surface portions is reflected by the arc-shaped reflection end surface portion 4 at a substantially right angle (parallel reflected light) with respect to the incident end surface portion 3 in the direction of the incident end surface portion 3, and the light source 8. The reflected light can be advanced in the direction without the light. Further, the reflection pattern 10 makes it difficult to encounter light traveling from the incident end surface portion 3 toward the reflection end surface portion 4, and conversely, an inclined surface 10b is formed such that light traveling from the reflection end surface portion 4 toward the incident end surface portion 3 is likely to be encountered. And a light guide plate capable of emitting emitted light from the surface portion 6 almost vertically and with high brightness at a position near the light source 8 without a constant light source, and a plane using the light guide plate. A lighting device can be provided.

  In the present invention, even if the light source 8 spreads light that is not parallel light (actually light perpendicular to the incident end face 3) with respect to the incident end face 3 of the light guide plate 2, the reflection end face of the light guide plate 2. 4 is formed into an arc shape in the direction of both side surfaces 5 and in the thickness direction. Further, with respect to the light traveling from the incident end surface portion 3 to the reflective end surface portion 4 facing the light, the spread of the light is reduced while the total reflection is repeated at the front surface portion 6 and the back surface portion 7, and the light is transmitted to the reflection pattern 10. The light is transmitted through the back surface portion 7 or the reflection angle due to total reflection is increased to advance toward the reflection end surface portion 4. The reflected light reflected by the reflection end face portion 4 travels in a direction in which the light source 8 does not exist due to the circular arc shape, travels substantially perpendicular to the incident end face portion 3, and spreads as it travels to the incident end face portion 3. Increase Thereby, it becomes easy to hit the inclined surface 10b of the reflective pattern 10, and light substantially perpendicular to the direction of the surface portion 6 can be emitted. Therefore, for example, a high-luminance color image can be obtained even if the pixels of the liquid crystal display device are small. Further, it is possible to provide the light guide plate 2 and the flat illumination device 1 that can obtain a high-density and clear image by reducing the pixels and increasing the absolute pixel amount.

1 is a schematic perspective view of a flat illumination device according to the present invention. It is an approximate light locus figure of the light guide plate concerning the present invention. It is an approximate light locus figure of the light guide plate concerning the present invention. It is an approximate light locus figure of the light guide plate concerning the present invention. It is a light locus figure of the side section of the light guide plate concerning the present invention. It is a light locus figure of the side section of the light guide plate concerning the present invention. It is a light locus figure of the side section of the light guide plate concerning the present invention. It is a light locus figure of the side section of the light guide plate concerning the present invention. It is an approximate light locus figure of the light guide plate concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar illumination apparatus 2 Light-guide plate 3 Incident end face part 4 Reflective end face part 5 Side face part 6 Front surface part 7 Back surface part 8 Light source 9 Reflector 10 Reflective pattern 10a Wall 10b Inclined surface Lo, Lr, Lo1, Loo, Lo2, Lfr, Lrb1 , Lrb2, Lfo, Lbr, Lfr, Lsr rays

Claims (7)

An incident end face part that guides light from the light source, a reflective end face part that reflects light that travels straight from the incident end face part, and faces the incident end face part, a surface part that emits the light, and a rear face that faces the surface part In the light guide plate composed of a portion and a side surface portion in contact with the incident end surface portion, the reflection end surface portion, the front surface portion, and the back surface portion,
The light traveling from the incident end face to the reflecting end face is shaped so as not to cause a taper leak, and the reflecting end face is reflected in the incident end face direction different from the incident light direction from the light source and the light source direction. A light guide plate having a reflective surface. 2. The reflected light incident from the light source, spread by an arbitrary refraction angle, travels to the reflection end face, and is reflected by the reflection end face is substantially perpendicular to the incident end face. Light guide plate. The incident light from the incident end surface portion on the back surface portion has a reflection pattern that does not reflect in the direction of the incident end surface portion and the surface portion but reflects only the reflected light from the reflection end surface portion. 1. The light guide plate according to 1. 4. The light guide plate according to claim 3, wherein the reflection pattern is single or / and continuous, and a pitch of the reflection pattern is uniform or gradation in the direction of the incident end face part and the reflection end face part. The said reflection end surface part has the circular arc shape extended in the thickness direction of the said surface part and the said back surface part, and / or the circular arc shape extended in at least 1 or more side surface part direction of Claim 1 characterized by the above-mentioned. Light guide plate. The light guide plate according to claim 1, wherein the side surface portion connects the incident end surface portion and the reflection end surface portion in a non-linear manner. At least one light source;
An incident end face portion that is located in the vicinity of the light source and guides light from the light source; a reflection end face portion that reflects light that has traveled straight from the incident end face portion and faces the incident end face portion; and a surface portion that emits the light. The back surface portion facing this surface portion, and the incident end surface portion, the reflection end surface portion, the side surface portion in contact with the front surface portion and the back surface portion, and the light traveling from the incident end surface portion to the reflection end surface portion has a taper leak. A light guide plate that has a shape that does not occur, and has a reflection surface that reflects the incident end surface direction different from the incident light direction and the light source direction of the reflected end surface portion, and
A flat illumination device comprising: a reflector provided at a lower portion of the back surface portion of the light guide plate.

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