JP4182076B2 - Light guide plate and flat illumination device - Google Patents

Description

  According to the present invention, the light guide plate is formed so that the position of the incident end surface portion is minimized, and the gentle first inclined surface portion and the sharp second inclined surface portion whose back surface faces in the opposite direction to the incident end surface portion. Even if the light from the light source has directivity, it does not cause taper leak when traveling from the incident end face to the non-incident end face, and is reflected by the anti-incident end face. When proceeding to the incident end face part, a taper leak occurs at the first inclined face part of the front face part or the back face part, the total reflection is performed and the light is emitted to the opposite surface, or the second slope of the back face part is obtained. A light guide plate that has a small total reflection angle at the surface portion and can be emitted at an angle substantially perpendicular to the surface portion, and an emitted light with a small exit angle with respect to the incident end surface portion and the anti-incident end surface portion of the light guide plate By a lenticular lens body provided on the upper side of the light guide plate on the outgoing light side. In addition, the outgoing light can further reduce the outgoing angle of the outgoing light in the direction perpendicular to the direction of the incident end face portion and the anti-incident end face portion, and avoid reflection of strong light from the light source in the vicinity of the incident end face portion. The present invention relates to a light guide plate and a flat illumination device capable of avoiding the generation of dark portions at both end portions near the incident end face portion of the light guide plate when the light source is provided near the side surface of the light guide plate.

  As a conventional light guide plate and flat illumination device, the light guide plate is formed into a so-called wedge shape, with the thickness decreasing as the distance from the incident end face portion increases in order to maximize the light from the light source. A method is known that utilizes a taper leak of light traveling from the end face to the direction opposite to the incident end face.

  Furthermore, in the case of a large flat illumination device, the thickness of the light guide is reduced as it is farther from the incident end face, and a taper leak of light from the incident end face to the opposite direction of the incident end face is used. There is known a method in which two opposite end faces of the light guide plate are made incident end face portions by using the method of the above.

  In addition, when printing a white light scattering agent on the opposite side of the exit surface of the conventional light guide plate, it is incident even when the printed portion is increased away from the incident end face portion or dots such as irregularities are provided on the light guide plate. The dots were increased as the distance from the end face portion increased.

In addition, as a conventional planar illumination device using a point light source such as an LED, a plurality of LEDs are arranged on the side surface of the light guide plate, and a convex or concave such as a prism is formed on the incident end surface of the light guide plate at a position facing these LEDs There is known a method of providing a shape so that the light beam reaches a part of both corners of the light guide plate.
JP 2003-337333 A JP 2003-029260 A

As the above-described conventional light guide plate and flat illumination device, the locus of light rays when light is incident on the wedge-shaped light guide plate 21 will be described with reference to FIGS.
As shown in FIG. 18, the conventional light guide plate 21 has a wedge shape in which the thickness decreases from the incident end surface portion 31 toward the counter incident end surface portion 41 located on the opposite side of the incident end surface portion 31. Therefore, while the incident light L01 travels to the counter-incident end surface portion 41 located on the opposite side of the incident end surface portion 31, the incident angle of the light beam L01 with respect to the surface portion 61 toward the surface portion 61 is within about 42 ° ( In the case of acrylic resin), the light is totally reflected by the front surface portion 61 and proceeds in the direction of the back surface portion 71 as a light ray L02. However, since the light guide plate 21 has a wedge shape that is thin with respect to the direction in which the light beam travels, the incident angle with respect to the back surface portion 71 is smaller than the critical angle, so the critical angle is broken and the light beam L03 and the light beam L04 are emitted from the back surface portion 71. End up.
Here, for the sake of explanation, the outgoing light that breaks the critical angle is shown only on the back surface portion 71, but the outgoing light that breaks the critical angle similarly exists on the front surface portion 61 as well.

  Thus, as shown in FIGS. 19A and 19B, the thickness of the light guide plate 21 is increased as the distance from the incident end face portion 31 is increased in order to make maximum use of light from the light source 9. In the method of using a tapered leak of light that is formed into a so-called wedge shape that is thinned and is directed from the incident end surface portion 31 in the opposite direction to the incident end surface portion 31, when the light source 9 is directional, the vicinity of the incident end surface portion 31 is obtained. Then, the critical angle is immediately broken, that is, high brightness light is emitted by the taper leak. Since this light is emitted light having high brightness and strong directivity, the shape of the semiconductor light emitting element 9 itself is observed (reflected) from the light emitting surface of the entire light source, for example, the light source 9 of the semiconductor light emitting element (LED). There is a problem that will be done.

  Furthermore, in the light guide plate 21 in which the thickness of the light guide plate is reduced as the distance from the incident end face portion 31 increases as described above, the shape of the semiconductor light emitting element 9 itself is not observed from the exit surface. Actually, since the vicinity of the incident end face portion 31 is not used, there is a problem that the light guide plate 21 larger than the necessary area of the flat illumination device must be used.

  Further, in the case of a conventional large flat illumination device, the thickness of the light guide plate 21 is reduced as the distance from the incident end surface portion 31 is decreased, and the light taper from the incident end surface portion 31 in the opposite direction to the incident end surface portion 31 is achieved. In the configuration in which the two opposing end faces of the light guide plate 21 are made incident end face portions 31 using a leak-utilizing method, the central portion of the light guide plate 21 has the smallest thickness as shown in FIG. As the weight is reduced, the thickness of the central portion is reduced and there is a problem in mechanical (structural) strength.

  Furthermore, in order to obtain white light by using three color light sources of RGB (red light emission, green light emission, blue light emission) as light sources, when each RGB light source is arranged in an array, each emission color is incident on the end face. It is difficult to mix in the vicinity of the part. For this reason, there is a problem in that each emission color does not become white in the vicinity of the incident end face portion and is emitted in a patchy manner from the emission surface.

  In addition, as a flat illumination device using a point light source such as an LED as a conventional light source, a plurality of LEDs are arranged on the incident end surface portion of the light guide plate, and a projection such as a prism is formed on the incident end surface portion of the light guide plate at a position facing these LEDs. In a configuration with a concave shape, the light source is a point light source, so the light beam intensity distribution is circular or elliptical, and prism processing is applied to the incident end surface portion of the light guide plate facing the light source, thereby moving the light source in the horizontal direction. However, there is a problem in that light from adjacent light sources such as LEDs overlaps to cause brightness spots.

  Further, in a conventional illumination device using a light guide plate and a point light source such as one LED at the center of the incident end face, as shown in FIGS. 19A and 19B, semiconductor light emission such as an LED is performed. In order to have directivity in the light source 9 of the element, the critical angle is broken while traveling in the direction of the anti-incident end face portion 41 in the narrow range and from the incident end face portion 31 in the direction of the anti-incident end face portion 41. There is a problem that both end portions of the incident end surface portion 31 (between the incident end surface portion 31 and the incident light beam L0) become dark portions.

  In addition, in the conventional light guide plate and flat illumination device, the light confined in the light guide plate is simply emitted by a taper leak or a groove or uneven shape provided on the front or back surface of the light guide plate. Are emitted or diffused as they are. For this reason, only light in a state where the luminance and energy of light are low can be emitted. For example, since the light is weak with respect to each pixel of RGB of the liquid crystal display device, the aperture area must be widened. It was an obstacle to miniaturize pixels.

  The present invention has been made to solve the above-described problems, and provides a light guide plate and a flat illumination device having the following characteristics. First, a light source having directivity, for example, monochromatic light of a plurality of semiconductor light emitting elements or red light, green light, three primary colors of blue light, or white light using a wavelength conversion material, and an array or directivity of a single unit A light source composed of the semiconductor light emitting element, an incident end face part that guides light from the light source, a surface part or / and a back part that emits the light, and a side part that intersects the front part and the back part at a substantially right angle The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion, and the distance between the front surface portion and the back surface portion at the anti-incident end surface portion that is the maximum separation distance from the incident end surface portion is The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the opposite direction to the incident end surface portion are alternately connected, and these surfaces form a mirror surface. With surface or / and back The light guide plate has a thin rectangular cubic shape with fine light deflection elements that increase as it approaches the incident end surface, and covers the portions other than the incident end surface and the exit surface of the light guide plate, and the reflective surface is uneven. By providing a reflector having a shape or a prism shape and a lenticular lens body provided on the upper side of the light exit surface of the light guide plate, the light beam guided from the incident end surface portion into the light guide plate is opposite to the incident end surface portion. There is no light beam that breaks the critical angle while proceeding to the anti-incident end face part located at, and many light rays are totally reflected on each surface of the light guide plate, and the angle at which the total reflection is made on the front and back parts is on the anti-incident end face part. As the light travels, the angle changes to a larger angle. When the light beam reflected by the non-incident end face part travels again in the direction of the incident end face part, there are many light rays that are deflected by the first inclined surface part and break the critical angle at the surface part or near the critical angle. Existed for the first time It can generate parleeks and breaks the critical angle when it reaches a fine light deflecting element and emits it from the light guide plate. The second inclined surface part totally emits light even if it is not close to the critical angle and emits directly from the surface part. In particular, the light totally reflected by the second inclined surface portion can obtain substantially vertical outgoing light.

  Further, by making the anti-incident end face part into a Fresnel lens shape, the reflected light toward the incident end face part at the anti-incident end face part can be reflected as a parallel light beam. Moreover, light can be disperse | distributed to a side part part by forming the convex-shaped and concave ridge extending between a surface part and a back surface part. For this reason, it is possible to obtain uniform emission light without spots from the emission surface of the light guide plate.

  Furthermore, by making the inclined surface of the cross section of the convex or concave ridge of the anti-incident end face portion into a straight or arcuate triangular shape, for example, a light guide plate having a wide width in the side surface direction, and a dot at the center of the incident end face portion. Even in the case of a light source having a shape, it is possible to obtain reflected light having a larger spread.

  Further, since the top of the ridge is cut out flat, it can be reflected in the direction of entering the counter-incident end face. Therefore, it is possible to obtain uniform emission light without spots from the emission surface of the light guide plate without being caught by the shape of the light source or the light guide plate.

  Further, since the thickness direction and the side surface direction of the anti-incident end surface portion are arc-shaped, it is possible to obtain a light collecting property on the reflected light at the anti-incident end surface portion. For this reason, in the case of a plurality of point light sources or the like, the reflected light from the light source is mixed with each other while hardly leaking from the side surface direction, and uniform outgoing light without spots can be obtained from the outgoing surface of the light guide plate.

  Furthermore, since the anti-incident end face part has an inclined surface part in the surface part direction or the back surface part direction, the reflected light at the anti-incident end face part is reflected in the first inclined surface part or the second inclined surface part direction, or the surface part. It can be reflected in the direction of the first inclined surface portion and the second inclined surface portion by reflecting twice in the inclined surface portion in the direction and the inclined surface portion in the back surface direction, and banding phenomenon such as dark lines and bright lines can be prevented, The emission angle from the emission surface can be controlled by controlling the angle of reflection in the direction of the first inclined surface portion or the second inclined surface portion.

  Furthermore, when the anti-incident end face portion has a fine corner cubic shape, for example, when it is a plurality of point light sources, the incident light and the reflection are the same in the fine corner cubic shape. Therefore, when the light is reflected at the anti-incident end face portion and returns to the incident end face portion direction, it is mixed in the light guide plate and reflected at the first inclined face portion or the second inclined face portion and reflected from the outgoing face direction. Some outgoing light can be obtained.

  In addition, the light guide plate has a lenticular lens body at the upper part on the exit surface side, and can be emitted almost vertically from the surface portion directly by performing total reflection even if the second inclined surface portion is not a light beam close to the critical angle, This substantially vertical emitted light is emitted as a light beam having a sharp peak width by propagation in the direction of the incident end face and the anti-incident end face (in this case, the Z direction). It can be focused in the left and right direction (XY direction) of the end face, and for example, a sharp light beam is emitted in each direction for each RGB pixel in the LCD, so that the aperture area of the pixel is reduced. Can do. Further, by reducing the size of each pixel of RGB, the amount of pixels per unit area can be increased more finely, so that a clear image can be provided.

  Furthermore, the reflection of light sources and brightness spots can be eliminated, and even in the case of a light source in which monochromatic light sources such as RGB are arranged, the light is not emitted immediately in the vicinity of the incident end face part, but once totally reflected on the opposite side of the incident end face part of the light guide plate. And then exit. For this reason, in order to proceed while repeating total reflection several times in the light guide plate in the meantime, RGB single color light can be mixed to obtain complete white light, and brightness spots and emission color spots can be controlled along with luminance. In addition, the light exiting surface of the light guide plate can be made large, and even with a large light guide plate or flat illumination device, the incident end surface portions at both ends in the vicinity of the light source have the minimum thickness and the central portion has the maximum thickness. A light guide plate and a flat illumination device can be provided.

The light guide plate according to claim 1 of the present invention has a thin rectangular cube shape, and the distance between the front surface portion and the back surface portion gradually increases as the distance from the incident end surface portion increases. The distance between the front surface and the back surface is maximized at the counter-incident end surface, which is the maximum separation distance from the light incident end surface, and the back surface is a mirror surface. Has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the opposite direction to the incident end surface portion are alternately and continuously connected, and a critical angle when proceeding from the incident end surface portion to the non-incident end surface portion. Without being broken, the critical angle is broken by the first inclined surface portion when it is reflected from the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, and a taper leak is generated and the reflection angle of total reflection by the second inclined surface portion that is emitted substantially perpendicular angle smaller And features.

The light guide plate according to claim 1 has a thin plate-like rectangular cube shape, and the distance between the front surface portion and the back surface portion is gradually increased as the distance from the incident end surface portion increases. The distance between the front and back surfaces becomes the maximum at the counter-incident end surface, which is the maximum separation distance from the incident end surface, and the back surface composed of the mirror surface is the incident end surface. The first inclined surface part and the sharp second inclined surface part facing in the opposite direction are connected in a staircase shape, and the critical angle is not broken when proceeding from the incident end face part to the anti-incident end face part. When the light is reflected at the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, the critical angle is broken by the first inclined surface portion to generate a taper leak, and the reflection angle of total reflection is substantially small by the second inclined surface portion. since emitted perpendicular angle, the incident end There is no light beam that breaks the critical angle while the light beam guided from the part into the light guide plate proceeds to the anti-incident end surface part located on the opposite side of the incident end surface part, and many light beams are totally reflected on each surface of the light guide plate, The angle of total reflection at the front and back surfaces changes to a larger angle toward the anti-incident end surface, and the light beam reflected at the anti-incident end surface is deflected by the first inclined surface when traveling again toward the incident end surface. There are many rays that break the critical angle or near the critical angle on the surface, and when the fine light deflection element is reached with the taper leak, the critical angle is broken and emitted from the light guide plate. Even if it is not a light beam close to, it can be totally reflected and emitted directly from the surface portion.

Further, the light guide plate according to claim 2 has a thin rectangular cube shape, and on the front surface portion and / or the back surface portion , fine dot-shaped light so that the quantity or area increases as the incident end surface portion is approached. A deflection element is provided, and the distance between the front and back surfaces is minimized at the incident end surface so that the distance between the front and back surfaces gradually increases as the distance from the incident end surface is increased. The first inclined surface portion where the distance between the front surface portion and the back surface portion is maximum at the anti-incident end surface portion that is the maximum separation distance from the end surface portion, and the back surface portion formed of the mirror surface is directed in the opposite direction to the incident end surface portion. And a sharp second inclined surface portion alternately and continuously connected to each other, and when proceeding from the incident end surface portion to the anti-incident end surface portion, the critical angle is not broken and the reflected light is reflected by the anti-incident end surface portion. From the first inclined surface portion to the incident end surface portion The field angle is broken to generate a taper leak, and the reflection angle of the total reflection is small and the light is emitted at a substantially vertical angle by the second inclined surface portion, and the light deflection element is inclined even when traveling from the incident end surface portion toward the non-incident end surface portion. A critical angle is broken by a surface and emitted .

The light guide plate according to claim 2 has a thin rectangular cube shape, and a fine dot-shaped light deflecting element such that the number or area of the front surface portion and / or the back surface portion increases as the distance from the incident end surface portion increases. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the incident end surface portion increases. The distance between the front surface portion and the back surface portion is maximum at the anti-incidence end surface portion that is the maximum separation distance from the surface, and the back surface portion formed of the mirror surface is sharp with the gentle first inclined surface portion facing in the opposite direction to the incident end surface portion. A staircase shape is formed in which the second inclined surface portions are alternately and continuously connected. When proceeding from the incident end surface portion to the anti-incident end surface portion, the critical angle is not broken and the light is reflected at the anti-incident end surface portion and incident from the anti-incident end surface portion. The critical angle by the first inclined surface when traveling to the end surface Breaking taper leak occurs, the reflection angle of total reflection is small and the light is emitted at a substantially vertical angle by the second inclined surface portion, and is also critical depending on the inclined surface of the light deflection element when traveling from the incident end surface portion toward the non-incident end surface portion. Since the light breaks off the corner and exits , the light beam guided into the light guide plate from the incident end surface portion does not break the critical angle while traveling to the counter-incident end surface portion located on the opposite side of the incident end surface portion, and each surface of the light guide plate The total reflection of many light beams at the front and back surfaces changes to a larger angle toward the anti-incident end surface, and the light reflected at the anti-incident end surface proceeds again toward the incident end surface. Sometimes there are many light beams that are deflected by the first inclined surface part and break the critical angle at the surface part or near the critical angle. When the fine light deflecting element is reached with the taper leak, the critical angle is broken and emitted from the light guide plate. , Even in the second inclined surface, not a ray close to the critical angle can be emitted directly from the surface portion subjected to total reflection. In addition, the light incident from the incident end face does not reach the critical angle even if it reaches the front or back surface of the light guide plate, and the light that has been totally reflected once by the anti-incident end face on the opposite side of the incident end face. Because there are many rays that break the critical angle or close to the critical angle, it is necessary to increase the amount of light emitted as it approaches the incident end surface in order to exit from the exit surface while returning from the anti-incident end surface to the incident end surface. Therefore, the closer to the incident end face portion, the more the number or area of the light deflection elements increases, so that uniform outgoing light can be obtained.

  Furthermore, the light guide plate according to claim 3 is characterized in that the inclination angle of the second inclined surface portion is not less than twice the inclination angle of the first inclined surface portion and not more than 90 °.

  In the light guide plate according to claim 3, since the inclination angle of the second inclined surface portion is not less than twice the inclination angle of the first inclined surface portion and not more than 90 °, the surface of the light totally reflected by the second inclined surface portion The deflection angle in the part direction increases.

  In the light guide plate according to claim 4, the anti-incident end surface portion is centered on the same distance position from the two side surface portions, and the Fresnel lens shape whose curvature changes in the direction of the side surface portion or between the front surface portion and the back surface portion. An extended convex or / and concave ridge is formed.

  The light guide plate according to claim 4 has the anti-incident end surface portion extending between the Fresnel lens shape or the front surface portion and the back surface portion whose curvature changes in the direction of the side surface centered at the same distance position from the two side surface portions. Since the convex or / and concave ridges are formed, the reflected light in the direction of the incident end face at the non-incident end face can be reflected as a parallel light beam, and the convex extending between the front surface and the back surface. By forming a ridge having a shape or a concave shape, light can be dispersed in the direction of the side surface.

  Furthermore, the light guide plate according to claim 5 is characterized in that the inclined surface of the cross section of the convex ridge and the concave ridge is a straight or arcuate triangular shape or the top of the ridge is notched flat.

In the light guide plate according to the fifth aspect, the convex ridge and the inclined surface of the cross section of the concave ridge are straight or arcuate triangular or the top of the ridge is notched flat. Even if there is a point light source at the center of the incident end face portion of the light plate, reflected light having a larger spread can be obtained.
Moreover, when the top part of a ridge is notched flat, it can reflect in the direction which approached the anti-incident end surface part.

  The light guide plate according to claim 6 is characterized in that the anti-incident end face part has an arc shape in the thickness direction of the front face part and the back face part and / or the side face part direction.

In the light guide plate according to claim 6, the anti-incident end face portion has an arc shape in the thickness direction of the front surface portion and the back surface portion and / or the side surface portion direction. Condensability can be obtained for the reflected light at the end face. Thereby, it can condense to the 1st inclined surface part and the 2nd inclined surface part direction without waste, and can obtain bright emitted light.
In addition, when the side surface direction is an arc shape, it is possible to obtain a light collecting property on the reflected light at the anti-incident end surface portion. Therefore, in the case of a plurality of point light sources, the reflected light from the light source is They are mixed with each other while preventing leakage.

  Furthermore, the light guide plate according to claim 7 is characterized in that the non-incident end surface portion has an inclined surface portion in a front surface portion direction and / or a back surface portion direction.

  In the light guide plate according to the seventh aspect, since the anti-incident end surface portion has the inclined surface portion in the front surface portion direction and / or the back surface portion direction, the reflected light at the anti-incident end surface portion is reflected by the first inclined surface portion or the second inclined surface portion. It can be reflected to the first inclined surface portion or the second inclined surface portion by reflecting in the surface portion direction or reflecting twice on the inclined surface portion in the front surface portion direction and the inclined surface portion in the rear surface portion direction.

  The light guide plate according to an eighth aspect is characterized in that the anti-incident end face portion has a fine corner cubic shape.

  In the light guide plate according to claim 8, since the anti-incident end surface portion has a fine corner cubic shape, for example, when it is a plurality of point light sources, the light from the plurality of light sources is within the fine corner cubic shape. In this case, the incident and reflection directions are the same, so when reflected in the anti-incident end face portion and mixed back in the incident end face portion direction, they are mixed in the light guide plate and reflected by the first inclined face portion and the second inclined face portion in the outgoing face direction. Is done.

Further, a flat illumination device according to claim 9 is a light source having directivity,
Forms an incident end face for guiding light from the light source, and a surface portion and / or back surface and emits the light, the thin plate rectangular cubic shape having a side portion intersecting to the these surface portions and the back portion, the incident The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the end surface portion increases, and the maximum separation distance from the incident end surface portion. The distance between the front surface portion and the back surface portion is maximum at the anti-incident end surface portion, and the back surface portion made of a mirror surface has a gentle first inclined surface portion and a sharp second inclination facing the opposite direction to the incident end surface portion. It has a staircase shape in which the surface portion is alternately and continuously connected, and does not break the critical angle when proceeding from the incident end surface portion to the anti-incident end surface portion, and is reflected at the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion. Sometimes the first inclined surface breaks the critical angle and tapers A light guide plate for emitting a substantially normal angle smaller reflection angle of the total reflection by the second inclined surface portion as well as generate,
And a reflector having reflectivity that covers portions other than the incident end face and the exit face of the light guide plate.

A flat illumination device according to claim 9 is a light source having directivity,
Forms an incident end face for guiding light from the light source, and a surface portion and / or back surface and emits the light, the thin plate rectangular cubic shape having a side portion intersecting to the these surface portions and the back portion, the incident The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the end surface portion increases, and the maximum separation distance from the incident end surface portion. The distance between the front surface portion and the back surface portion is maximum at the anti-incident end surface portion, and the back surface portion made of a mirror surface has a gentle first inclined surface portion and a sharp second inclination facing the opposite direction to the incident end surface portion. It has a staircase shape in which the surface portion is alternately and continuously connected, and does not break the critical angle when proceeding from the incident end surface portion to the anti-incident end surface portion, and is reflected at the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion. Sometimes the first inclined surface breaks the critical angle and tapers A light guide plate for emitting a substantially normal angle smaller reflection angle of the total reflection by the second inclined surface portion as well as generate,
A light-reflecting reflector that covers a portion other than the incident end face and the exit face of the light guide plate, so that the light beam guided from the incident end face into the light guide plate is located on the opposite side of the incident end face. There is no light beam that breaks the critical angle while going to the incident end face, and many light rays are totally reflected on each surface of the light guide plate. to change, light, etc. many present near the light and the critical angle break the critical angle at the first deflected by the inclined surface portion surface portion when going light again incident end face direction reflected by the anti-incident end face, this Therefore, taper leak does not occur in the vicinity of the incident end face, so even with a highly directional light source, the emitted light of the light intensity near the incident end face and the shape of the light source such as the semiconductor light emitting element itself are observed (reflected). ) Or brightness spots.

  Furthermore, since a taper leak can be caused only by a light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, it does not immediately emit near the incident end face part. For this reason, it is possible to avoid the occurrence of light emission color spots, and the incident light is totally reflected once on the opposite side of the incident end face portion of the light guide plate, and then emitted, so the total reflection in the light guide plate is repeated several times during that time. However, in order to proceed, RGB monochromatic light is mixed and complete white light can be obtained.

A planar illumination device according to claim 10 is a light source having directivity,
A thin plate-like rectangular cube shape having an incident end face part that guides light from the light source, a surface part or / and a back part that emits the light, and a side part that intersects with the front part and the back part, In the area or / and the back surface, a fine dot-shaped light deflecting element is provided so that the quantity or area increases as it approaches the incident end surface, and the distance between the front surface and the back surface increases as the distance from the incident end surface increases. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance gradually increases, and between the front surface portion and the back surface portion at the anti-incident end surface portion that is the maximum separation distance from the incident end surface portion. The back surface portion made of a mirror surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion that are opposite to the incident end surface portion are alternately and continuously connected, Critical when traveling from the incident end face to the anti-incident end face Without being broken, the critical angle is broken by the first inclined surface portion when it is reflected from the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, and a taper leak is generated and the reflection angle of total reflection by the second inclined surface portion A light guide plate that emits light at a small and substantially vertical angle;
And a reflector having reflectivity that covers portions other than the incident end face and the exit face of the light guide plate.

A planar illumination device according to claim 10 is a light source having directivity,
A thin plate-like rectangular cube shape having an incident end face part that guides light from the light source, a surface part or / and a back part that emits the light, and a side part that intersects with the front part and the back part, In the area or / and the back surface, a fine dot-shaped light deflecting element is provided so that the quantity or area increases as it approaches the incident end surface, and the distance between the front surface and the back surface increases as the distance from the incident end surface increases. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance gradually increases, and between the front surface portion and the back surface portion at the anti-incident end surface portion that is the maximum separation distance from the incident end surface portion. The back surface portion made of a mirror surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion that are opposite to the incident end surface portion are alternately and continuously connected, Critical when traveling from the incident end face to the anti-incident end face Without being broken, the critical angle is broken by the first inclined surface portion when it is reflected from the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, and a taper leak is generated and the reflection angle of total reflection by the second inclined surface portion A light guide plate that emits light at a small and substantially vertical angle;
A light-reflecting reflector that covers a portion other than the incident end face and the exit face of the light guide plate, so that the light beam guided from the incident end face into the light guide plate is located on the opposite side of the incident end face. There is no light beam that breaks the critical angle while going to the incident end face, and many light rays are totally reflected on each surface of the light guide plate. When the light beam reflected by the non-incident end face portion again travels in the direction of the incident end face portion, there are many light rays that are deflected by the first inclined surface portion and break the critical angle at the surface portion or near the critical angle, and are tapered. When a fine light deflecting element is reached together with a leak, the critical angle is broken and emitted from the light guide plate, and the second inclined surface portion can be directly reflected from the surface portion by performing total reflection even if the light beam is not close to the critical angle. In addition, the light incident from the incident end face does not reach the critical angle even if it reaches the front or back surface of the light guide plate, and the light that has been totally reflected once by the anti-incident end face on the opposite side of the incident end face. Because there are many rays that break the critical angle or close to the critical angle, it is necessary to increase the amount of light emitted as it approaches the incident end surface in order to exit from the exit surface while returning from the anti-incident end surface to the incident end surface. Therefore, the closer to the incident end face portion, the more the number or area of the light deflection elements increases, so that uniform outgoing light can be obtained.

Furthermore, since the taper leak can be caused only by the light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, the light is not emitted immediately in the vicinity of the incident end face part. For this reason, it is possible to avoid the occurrence of light emission color spots, and the incident light is totally reflected once on the opposite side of the incident end face portion of the light guide plate, and then emitted, so the total reflection in the light guide plate is repeated several times during that time. However, in order to proceed, RGB monochromatic light is mixed and complete white light can be obtained.

The flat illumination device according to an eleventh aspect is characterized in that a lenticular lens body is provided in an upper portion on the light exit surface side of the light guide plate.

Since the planar illumination device according to claim 11 includes a lenticular lens body on the light exit surface of the light guide plate, the second inclined surface portion performs total reflection even if the light beam is not close to the critical angle, and directly from the surface portion. The substantially perpendicular emission light can be emitted substantially vertically, and the light emitted as a light beam having a sharp peak width by propagation in the direction of the incident end face portion and the anti-incident end face portion (here, Z direction) is lenticular. The lens body can collect light in the left-right direction (XY direction) of the incident end surface portion and the anti-incident end surface portion.

Furthermore, in the planar illumination device according to claim 12 , the light source is composed of a directional semiconductor light-emitting element, and is monochromatic light or red light, green light, blue light, three primary colors, or white light using a wavelength conversion material. These are configured as a single body or an array.

In the planar illumination device according to claim 12 , the light source is composed of a directional semiconductor light emitting element, and is monochromatic light or red light, green light, blue light, or primary light of wavelength conversion material or white light using a wavelength conversion material. Since it is configured as a single unit or an array, it is possible to obtain high-luminance outgoing light and to emit high-luminance white light according to the purpose. It is possible to obtain outgoing light that is free from observation (reflection) and luminance spots.

The flat illumination device according to claim 13 is characterized in that the reflection surface of the reflector has an uneven shape or a prism shape.

In the planar illumination device according to the thirteenth aspect, since the reflecting surface of the reflector has a concavo-convex shape or a prism shape, the light beam or the exit surface that has traveled from the incident end surface portion to the counter-incident end surface portion located on the opposite side of the incident end surface portion The light emitted to the opposite surface or the leaked light can be returned to the light guide plate more reliably, and the position to return to the light guide plate can be controlled again by controlling the uneven shape and prism shape. . Further, when the light source is light of three primary colors such as RGB, the light of the three primary colors can be mixed in the light guide plate by reflection by the prism surface.

As described above, the light guide plate according to claim 1 has a thin rectangular cube shape, and the distance between the surface portion and the back surface portion gradually increases as the distance from the incident end surface portion increases. minimum becomes a period of distance incidence end face of the back portion, a period of the distance between the surface portion and the back portion in the counter-incident end face which is the maximum distance away from the incident end face is maximized, consisting mirror The back surface portion has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the opposite direction to the incident end surface portion are alternately and continuously connected, and when proceeding from the incident end surface portion to the anti-incident end surface portion Without breaking the critical angle, it is reflected at the anti-incident end face part and travels from the anti-incident end face part to the incident end face part, breaks the critical angle by the first inclined face part, generates a taper leak, and is totally reflected by the second inclined face part. The light is emitted at a small angle with a small reflection angle. Since light rays break critical angle between guided from the incident end face in the light guide plate beam traveling counter-incident end surface portion located on the opposite side of the entrance end face is not a lot of light on each side of the light guide plate The angle at which the light is totally reflected and totally reflected on the front surface portion and the back surface portion changes to a larger angle toward the anti-incident end surface portion, and the first inclination is obtained when the light beam reflected on the anti-incident end surface portion travels again toward the incident end surface portion. There are many rays that are deflected by the surface part and break the critical angle at the surface part or near the critical angle. When the fine light deflecting element is reached together with the taper leak, the critical angle is broken and emitted from the light guide plate. Even if the light is not close to the critical angle, it can be totally reflected at the surface portion and can be directly emitted from the surface portion. In particular, light that has been totally reflected by the second inclined surface portion can obtain substantially vertical outgoing light.

  Therefore, the amount of light can be controlled, the light source is not reflected, and bright uniform outgoing light can be obtained without dark portions at both ends of the incident end surface near the incident end surface. For this reason, the area of the light guide plate that can actually be used can be increased, and even if the light sources are provided in parallel (array shape), the occurrence of luminance spots is prevented without overlapping light from adjacent light sources. be able to. Further, when the size is increased, both ends are set as incident end faces, and the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

Furthermore, since the taper leak can be caused only by the light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, the light is not emitted immediately in the vicinity of the incident end face part. For this reason, it is possible to avoid the occurrence of light emission color spots, and the incident light is totally reflected once on the opposite side of the incident end face portion of the light guide plate, and then emitted, so the total reflection in the light guide plate is repeated several times during that time. However, in order to proceed, RGB monochromatic light is mixed and complete white light can be obtained.

Further, the light guide plate according to claim 2 has a thin rectangular cube shape, and on the front surface portion and / or the back surface portion , fine dot-shaped light so that the quantity or area increases as the incident end surface portion is approached. A deflection element is provided, and the distance between the front and back surfaces is minimized at the incident end surface so that the distance between the front and back surfaces gradually increases as the distance from the incident end surface is increased. The first inclined surface portion where the distance between the front surface portion and the back surface portion is maximum at the anti-incident end surface portion that is the maximum separation distance from the end surface portion, and the back surface portion formed of the mirror surface is directed in the opposite direction to the incident end surface portion. And a sharp second inclined surface portion alternately and continuously connected to each other, and when proceeding from the incident end surface portion to the anti-incident end surface portion, the critical angle is not broken and the reflected light is reflected by the anti-incident end surface portion. From the first inclined surface portion to the incident end surface portion The field angle is broken to generate a taper leak, and the reflection angle of the total reflection is small and the light is emitted at a substantially vertical angle by the second inclined surface portion, and the light deflection element is inclined even when traveling from the incident end surface portion toward the non-incident end surface portion. Since the light breaks off the critical angle by the surface, the light beam guided from the incident end surface part into the light guide plate does not break the critical angle while proceeding to the anti-incident end surface part located on the opposite side of the incident end surface part, and the light guide plate Many rays are totally reflected on each surface of the surface, and the angle of total reflection on the front surface portion and the back surface portion changes to a larger angle toward the anti-incident end surface portion, and the light rays reflected on the anti-incident end surface portion are incident again on the incident end surface portion. There are many light rays that are deflected by the first inclined surface part and break the critical angle at the surface part when traveling in the direction, or light rays close to the critical angle, etc., and break the critical angle when reaching a fine light deflecting element with taper leak. Out of And it can be emitted from the surface directly unit performs total reflection even in the second inclined surface, not a ray close to the critical angle. In addition, the light incident from the incident end face does not reach the critical angle even if it reaches the front or back surface of the light guide plate, and the light that has been totally reflected once by the anti-incident end face on the opposite side of the incident end face. Because there are many rays that break the critical angle or close to the critical angle, it is necessary to increase the amount of light emitted as it approaches the incident end surface in order to exit from the exit surface while returning from the anti-incident end surface to the incident end surface. Therefore, the closer to the incident end face portion, the more the number or area of the light deflection elements increases, so that uniform outgoing light can be obtained.

Therefore, the amount of light can be controlled, the light source is not reflected, and bright uniform outgoing light can be obtained without dark portions at both ends of the incident end surface near the incident end surface. For this reason, the area of the light guide plate that can actually be used can be increased, and even if the light sources are provided in parallel (array shape), the occurrence of luminance spots is prevented without overlapping light from adjacent light sources. be able to. Further, when the size is increased, both ends are set as incident end faces, and the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

Furthermore, since the taper leak can be caused only by the light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, the light is not emitted immediately in the vicinity of the incident end face part. For this reason, it is possible to avoid the occurrence of light emission color spots, and the incident light is totally reflected once on the opposite side of the incident end face portion of the light guide plate, and then emitted, so the total reflection in the light guide plate is repeated several times during that time. However, in order to proceed, RGB monochromatic light is mixed and complete white light can be obtained.

  Furthermore, the light guide plate according to claim 3 is such that the angle of inclination of the second inclined surface portion is not less than twice the angle of inclination of the first inclined surface portion and not more than 90 °, and therefore the light totally reflected by the second inclined surface portion. The angle of deflection in the direction of the surface portion increases. Therefore, the angle of incidence on the surface portion is reduced, and the emitted light is easily emitted in the vertical direction.

  In the light guide plate according to claim 4, the anti-incident end surface portion is centered on the same distance position from the two side surface portions, and the Fresnel lens shape whose curvature changes in the direction of the side surface portion or between the front surface portion and the back surface portion. Since the extending convex or / and concave ridges are formed, the reflected light in the direction of the incident end face at the non-incident end face can be reflected as a parallel light beam, extending between the front surface and the back surface. By forming the existing convex or concave ridges, the light can be dispersed in the direction of the side surface. Therefore, uniform emission light without spots can be obtained from the emission surface of the light guide plate.

In the light guide plate according to the fifth aspect, the convex ridge and the inclined surface of the cross section of the concave ridge are straight or arcuate triangular or the top of the ridge is notched flat. Even if there is a point light source at the center of the incident end face portion of the light plate, reflected light having a larger spread can be obtained.
Moreover, when the top part of a ridge is notched flat, it can reflect in the direction which approached the anti-incident end surface part.
Therefore, it is possible to obtain uniform emission light without spots from the emission surface of the light guide plate without being caught by the shape of the light source or the light guide plate.

In the light guide plate according to claim 6, the anti-incident end face portion has an arc shape in the thickness direction of the front surface portion and the back surface portion and / or the side surface portion direction. Condensability can be obtained for the reflected light at the end face. Thereby, it can condense to the 1st inclined surface part and the 2nd inclined surface part direction without waste, and can obtain bright emitted light.
In addition, when the side surface direction is an arc shape, it is possible to obtain a light collecting property on the reflected light at the anti-incident end surface portion. Therefore, in the case of a plurality of point light sources, the reflected light from the light source is They are mixed with each other while preventing leakage. Therefore, uniform outgoing light without spots can be obtained from the outgoing surface of the light guide plate.
Further, when the anti-incident end surface portion has a circular shape in the thickness direction and the side surface direction between the front surface portion and the back surface portion, a so-called toric lens can be obtained. Therefore, since one light source has two focal points, light existing inside the light guide plate can be used without waste.

  In the light guide plate according to the seventh aspect, since the anti-incident end surface portion has the inclined surface portion in the front surface portion direction and / or the back surface portion direction, the reflected light at the anti-incident end surface portion is reflected by the first inclined surface portion or the second inclined surface portion. It can be reflected to the first inclined surface portion or the second inclined surface portion by reflecting in the surface portion direction or reflecting twice on the inclined surface portion in the front surface portion direction and the inclined surface portion in the rear surface portion direction.

  In the light guide plate according to claim 8, since the anti-incident end surface portion has a fine corner cubic shape, for example, when it is a plurality of point light sources, the light from the plurality of light sources is within the fine corner cubic shape. In this case, the incident and reflection directions are the same, so when reflected in the anti-incident end face portion and mixed back in the incident end face portion direction, they are mixed in the light guide plate and reflected by the first inclined face portion and the second inclined face portion in the outgoing face direction. Is done. Therefore, it is possible to obtain outgoing light having a spread from the outgoing surface.

Further, a flat illumination device according to claim 9 is a light source having directivity,
Forms an incident end face for guiding light from the light source, and a surface portion and / or back surface and emits the light, the thin plate rectangular cubic shape having a side portion intersecting to the these surface portions and the back portion, the incident The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the end surface portion increases, and the maximum separation distance from the incident end surface portion. The distance between the front surface portion and the back surface portion is maximum at the anti-incident end surface portion, and the back surface portion made of a mirror surface has a gentle first inclined surface portion and a sharp second inclination facing the opposite direction to the incident end surface portion. It has a staircase shape in which the surface portion is alternately and continuously connected, and does not break the critical angle when proceeding from the incident end surface portion to the anti-incident end surface portion, and is reflected at the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion. Sometimes the first inclined surface breaks the critical angle and tapers A light guide plate for emitting a substantially normal angle smaller reflection angle of the total reflection by the second inclined surface portion as well as generate,
A light-reflecting reflector that covers a portion other than the incident end face and the exit face of the light guide plate, so that the light beam guided from the incident end face into the light guide plate is located on the opposite side of the incident end face. There is no light beam that breaks the critical angle while going to the incident end face, and many light rays are totally reflected on each surface of the light guide plate. to change, light, etc. many present near the light and the critical angle break the critical angle at the first deflected by the inclined surface portion surface portion when going light again incident end face direction reflected by the anti-incident end face, this Therefore, taper leak does not occur in the vicinity of the incident end face, so even with a highly directional light source, the emitted light of the light intensity near the incident end face and the shape of the light source such as the semiconductor light emitting element itself are observed (reflected). ) Or brightness spots.

  Therefore, the amount of light can be controlled, the light source is not reflected, and both the ends of the incident end face near the incident end face have no dark part and bright uniform emitted light can be obtained. As a result, the area of the light guide plate that can be actually used can be increased, and even if the light sources are arranged in parallel (array shape), the occurrence of luminance spots is prevented without overlapping light from adjacent light sources. In addition, when the size of the light guide plate is increased, both ends are made incident end face portions, so that the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

  Furthermore, since a taper leak can only occur due to a light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, light is not emitted immediately in the vicinity of the incident end face part. In order for incident light to be emitted after being totally reflected once on the opposite side of the incident end face portion of the light guide plate, in order to travel while repeating total reflection several times in the light guide plate, Monochromatic light can be mixed to obtain complete white light.

A planar illumination device according to claim 10 is a light source having directivity,
A thin plate-like rectangular cube shape having an incident end face part that guides light from the light source, a surface part or / and a back part that emits the light, and a side part that intersects with the front part and the back part, In the area or / and the back surface, a fine dot-shaped light deflecting element is provided so that the quantity or area increases as it approaches the incident end surface, and the distance between the front surface and the back surface increases as the distance from the incident end surface increases. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance gradually increases, and between the front surface portion and the back surface portion at the anti-incident end surface portion that is the maximum separation distance from the incident end surface portion. The back surface portion made of a mirror surface has a staircase shape in which a gentle first inclined surface portion and a sharp second inclined surface portion that are opposite to the incident end surface portion are alternately and continuously connected, Critical when traveling from the incident end face to the anti-incident end face Without being broken, the critical angle is broken by the first inclined surface portion when it is reflected from the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, and a taper leak is generated and the reflection angle of total reflection by the second inclined surface portion A light guide plate that emits light at a small and substantially vertical angle;
A light-reflecting reflector that covers a portion other than the incident end face and the exit face of the light guide plate, so that the light beam guided from the incident end face into the light guide plate is located on the opposite side of the incident end face. There is no light beam that breaks the critical angle while going to the incident end face, and many light rays are totally reflected on each surface of the light guide plate. When the light beam reflected by the non-incident end face portion again travels in the direction of the incident end face portion, there are many light rays that are deflected by the first inclined surface portion and break the critical angle at the surface portion or near the critical angle, and are tapered. When a fine light deflecting element is reached together with a leak, the critical angle is broken and emitted from the light guide plate, and the second inclined surface portion can be directly reflected from the surface portion by performing total reflection even if the light beam is not close to the critical angle. In addition, the light incident from the incident end face does not reach the critical angle even if it reaches the front or back surface of the light guide plate, and the light that has been totally reflected once by the anti-incident end face on the opposite side of the incident end face. Because there are many rays that break the critical angle or close to the critical angle, it is necessary to increase the amount of light emitted as it approaches the incident end surface in order to exit from the exit surface while returning from the anti-incident end surface to the incident end surface. Therefore, the closer to the incident end face portion, the more the number or area of the light deflection elements increases, so that uniform outgoing light can be obtained.

Therefore, the amount of light can be controlled, the light source is not reflected, and both the ends of the incident end face near the incident end face have no dark part and bright uniform emitted light can be obtained. As a result, the area of the light guide plate that can be actually used can be increased, and even if the light sources are arranged in parallel (array shape), the occurrence of luminance spots is prevented without overlapping light from adjacent light sources. In addition, when the size of the light guide plate is increased, both ends are made incident end face portions, so that the thickness of the central portion is the thickest, so that the light guide plate is excellent in mechanical stability and strength.

Furthermore, since the taper leak can be caused only by the light beam totally reflected at the anti-incident end face part, even in the case of a light source in which monochromatic light sources such as RGB are arranged, the light is not emitted immediately in the vicinity of the incident end face part. For this reason, it is possible to avoid the occurrence of light emission color spots, and the incident light is totally reflected once on the opposite side of the incident end face portion of the light guide plate, and then emitted, so the total reflection in the light guide plate is repeated several times during that time. However, in order to proceed, RGB monochromatic light is mixed and complete white light can be obtained.

Since the planar illumination device according to the eleventh aspect includes the lenticular lens body at the upper part on the light exit surface side of the light guide plate, the second inclined surface portion performs total reflection even if the light beam is not close to the critical angle, and is substantially directly from the surface portion. The substantially perpendicular emission light can be emitted vertically, and the light emitted as a light beam having a sharp peak width by propagation in the direction of the incident end face portion and the anti-incident end face portion (here, the Z direction) is lenticular lens. The light can be condensed in the left-right direction (XY direction) of the incident end face part and the anti-incident end face part by the body.

  Therefore, for example, a sharp light beam is emitted in each direction with respect to each pixel of RGB on the LCD, so that the aperture area of the pixel can be reduced. For this reason, by reducing the size of each pixel of RGB, it is possible to increase the amount of pixels per unit area that is finer, and to provide a clear image.

Furthermore, in the planar illumination device according to claim 12 , the light source is composed of a directional semiconductor light-emitting element, and is monochromatic light or red light, green light, blue light, three primary colors, or white light using a wavelength conversion material. Since these are configured as a single unit or an array, it is possible to obtain high-intensity outgoing light and to emit high-intensity white light according to the purpose. By configuring in an array, the shape of the light source is emitted. From the surface, it is possible to obtain outgoing light that is free from observation (reflection) and luminance spots. Therefore, depending on the purpose, it can be provided on the side of the light guide plate instead of the CCFL or at the corner of the light guide plate to emit high-intensity white light, and clear white light or monochromatic light can be obtained. .

In the flat illumination device according to claim 13 , since the reflecting surface of the reflector has an uneven shape or a prism shape, the light beam or the light emitted from the incident end surface portion to the counter incident end surface portion located on the opposite side of the incident end surface portion It is possible to return the light emitted from the surface opposite to the surface or leaked light into the light guide plate more reliably, and to control the position to return to the light guide plate again by controlling the uneven shape and prism shape. Further, when the light source is light of three primary colors such as RGB, the light of the three primary colors can be mixed in the light guide plate by reflection by the prism surface.

  Therefore, it is possible to control the position of returning to the light guide plate again by controlling the concavo-convex shape and the prism shape, and it is possible to adjust the luminance, light amount distribution, emission angle, and the like of the final emitted light. Further, when the light source is light of three primary colors such as RGB, the light of the three primary colors can be mixed in the light guide plate by reflection by the prism surface. For this reason, the efficiency which converts the light from a light source into the emitted light of a light-guide plate without wasting is excellent.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the present invention, the light guide plate has a thin rectangular cube shape, and the distance between the front surface portion and the back surface portion is the minimum at the incident end surface portion, and the anti-incident end surface portion is the maximum separation distance from the incident end surface portion. These surfaces have a staircase shape in which the first distance between the first inclined surface portion and the second inclined surface portion, which have a back surface facing away from the incident end surface portion, are alternately and continuously connected. Has a mirror surface and is provided with fine light deflection elements on the front surface and the back surface, and covers the light guide plate, the light source having directivity, and the portions other than the incident end surface and the output surface of the light guide plate. By including a reflector having reflectivity and a lenticular lens body on the light exit side of the light guide plate, reflection of the light source near the incident end surface portion of the light guide plate and generation of luminance spots and light emission color spots As well as the light guide plate The exit surface larger take the light guide plate and is intended to provide a planar lighting device.

  1 is a schematic perspective view showing an example of a flat illumination device according to the present invention, FIG. 2 is a schematic cross-sectional view and a trajectory diagram showing an example of a light guide plate according to the present invention, and FIG. 3 is a partial schematic diagram of the light guide plate according to the present invention. 4 is a schematic perspective view showing another example of the light guide plate according to the present invention, FIG. 5 is a schematic perspective view showing another example of the light guide plate according to the present invention, and FIG. FIG. 7 is a partial schematic perspective view showing another example of the light guide plate according to the present invention, and FIG. 8 is a schematic plan view showing another example of the light guide plate according to the present invention. 9 is a schematic perspective view showing another example of the light guide plate according to the present invention, FIG. 10 is a schematic perspective view showing another example of the light guide plate according to the present invention, and FIG. 11 is a diagram of the light guide plate according to the present invention. 12 is a schematic perspective view showing another example, FIG. 12 is a schematic cross-sectional view and a locus diagram showing another example of the light guide plate according to the present invention, and FIG. 13 is a schematic plan view showing another example of the light guide plate according to the present invention. 14 (a) to (f) are partially enlarged views showing examples of convex ridges and concave ridges provided on the light guide plate according to the present invention, and FIG. 15 is an explanatory diagram according to the present invention. FIG. 16 is a schematic perspective view showing another example of the flat illumination device according to the present invention, and FIGS. 17A to 17F are schematic plan views as seen from the back surface side showing another example of the light guide plate according to the present invention. FIG.

  A flat illumination device 1 (1A) shown in FIG. 1 includes a light guide plate 2 (2A), a light source 10, a reflector 11, and a lenticular lens body 12.

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, and includes an incident end face portion 3 that guides light from the light source 10, and the incident end face. The anti-incident end face part 4 located on the opposite side to the part 3, the surface part 8 for emitting light, the back part 5 located on the opposite side of the surface part 8, and the surface part 8 and the back part 5 are connected. It consists of a side part 14. Although not shown in the figure, the front surface portion 8 and the back surface portion 5 of the light guide plate 2 are processed, for example, as described in Japanese Patent Application Laid-Open No. 2003-035824 as a light deflection element that totally reflects or refracts light. ing.
In the example of FIG. 1, one side surface of the rectangular light guide plate 2A is used as the incident end surface portion 3, but the incident end surface portion 3 may be anywhere on the peripheral side of the light guide plate 2, and the shape is not limited. Absent.

  In the light guide plate 2, the distance between the front surface portion 8 and the back surface portion 5 (thickness of the light guide plate 2) is minimum (thin) at the incident end surface portion 3, and at least the maximum separation distance from the incident end surface portion 3. The distance (thickness) is maximized (thick) at the (anti-incident end face portion 4 located on the opposite side of the incident end face portion 3). The light source 10 is disposed in the vicinity of the incident end face portion 3 where the thickness of the light guide plate 2 is thin, and the light guide plate 2 is disposed on the opposite side (maximum separation distance) of the light guide plate 2.

  Further, the back surface portion 5 of the light guide plate 2 has a first inclined surface portion 6 and a sharp second inclined surface portion 7 alternately and continuously facing the direction opposite to the incident end surface portion 3 (the anti-incident end surface portion 4). It has a connected staircase shape. Actually, the inclination angle of each first inclined surface portion 6 is an inclination angle of a straight line connecting the rear surface portion 5 side corner portion of the incident end surface portion 3 and the rear surface portion 5 side corner portion of the anti-incident end surface portion 4 ( The angle with the surface portion 8). Further, each second inclined surface portion 7 is set to be twice or more the inclination angle of the first inclined surface portion 6, and the angle formed with the flat surface portion 8 is set to 90 ° or less. The surfaces of the first inclined surface portion 6 and the second inclined surface portion 7 are mirror surfaces.

  In the light guide plate 2A shown in FIG. 1 and FIG. 2, each step-shaped boundary line composed of the first inclined surface portion 6 and the second inclined surface portion 7 forms a straight line parallel to the incident end surface portion 3, and each boundary The distance between the lines is equal. In addition, when 2 A of light-guide plates are large, it is preferable to lengthen the distance between each boundary line, so that it leaves | separates from the incident end surface part 3. FIG.

  Although not shown, the light deflection element described in, for example, Japanese Patent Application Laid-Open No. 2003-035824 is provided on the front surface portion 8 and the back surface portion 5 of the light guide plate 2. As a result, while the incident light from the incident end surface portion 3 travels to the anti-incident end surface portion 4 located on the opposite side of the incident end surface portion 3, even if the light guide plate 2 has a wedge shape, there is no ray breaking the critical angle. The light is totally reflected at the anti-incidence end face portion 4, and when the light beam travels again in the direction of the incident end face portion 3, it can be refracted by the light deflecting element to break the critical angle and be emitted from the surface portion 8.

Further, the light incident on the light guide plate 2 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, light from the front surface portion 8 direction of the incident end surface portion 3 to the rear surface portion 5 direction and the back surface The maximum incident angle of light from the portion 5 direction to the surface portion 8 direction is 90 °, and the refraction angle γ refracted at the incident end surface portion 3 is in the range of γ = 0 to ± 42 °.
However, only γ = −42 ° only in the direction of the back surface 5 near the front surface portion 8 and only γ = + 42 ° only in the direction of the front surface portion 8 near the back surface portion 5.

  Further, the light incident on the light guide plate 2 within the range of the refraction angle γ = 0 to ± 42 ° is Sin α = (1 / n) at the boundary surface between the light guide plate 2 and the air layer (refractive index n = 1). ) Can be used to express the critical angle. 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 °, and the surface portion 8 of the light guide plate 2 If there is no convex or concave for deflecting the light beam on the back surface part 5 or the critical angle α is not exceeded, the light in the light guide plate 2 is totally reflected by the front surface part 8 and the back surface part 5 while facing the anti-incident end face part 4 To go to.

However, in the light guide plate 2 of the present invention, the thickness (the distance between the front surface portion 8 and the back surface portion 5) is directed from the incident end surface portion 3 to the anti-incident end surface portion 4 located on the opposite side of the incident end surface portion 3. Wedge shape that becomes thicker (thickest at the maximum separation distance from the incident end face portion 3) (opposite to the wedge shape that decreases in thickness toward the maximum separation distance from the incident end face portion as in a general or conventional light guide plate) Therefore, as shown in FIG. 3, even if the light guide plate 2 is wedge-shaped while the incident light Ln1 from the incident end surface portion 3 proceeds to the anti-incident end surface portion 4 located on the opposite side of the incident end surface portion 3. There is no light beam that breaks the critical angle, and the light beam Ln2 that has undergone total reflection at the front surface portion 8 and the back surface portion 5 undergoes total reflection at the anti-incident end surface portion 4, and light deflects when the light beam Ln3 travels again in the direction of the incident end surface portion 3. The element 13 can be refracted or the like to break the critical angle and emit from the surface portion 8 as the light ray Ln4. Kill.
Here, although the convex shape and the concave shape are described with respect to the light deflecting element 13, both are refracted by the convex or concave inclined surface and emitted to the outside.

  Furthermore, although not shown, the light guide plate 2 of the present example is provided with the light deflection elements 13 on the front surface portion 8 and the back surface portion 5 so that the quantity or area increases as it approaches the incident end surface portion 3. As a result, the light that first enters the incident end face portion 3 from the light source 10 does not reach the critical angle α even if it reaches the front surface portion 8 or the back surface portion 5 of the light guide plate 2, and the front surface portion 8 or the back surface portion 5. Then, while repeating total reflection, the light proceeds to the anti-incident end surface portion 4 on the opposite side of the incident end surface portion 3, totally reflected by the anti-incident end surface portion 4, and again traveled in the direction of the incident end surface portion 3. There are many light rays that gradually become thinner and break the critical angle α, light rays that are close to the critical angle α, and the like, and light rays near the critical angle α are reflected by the light deflection element 13 while returning from the anti-incident end face portion 4 to the incident end face portion 3. Refraction or the like is caused by the inclined surface, and the light exits from the exit surface (surface portion 8).

Further, while returning from the non-incident end face part 4 to the incident end face part 3, the light exits from the exit surface (surface part 8) and approaches the incident end face part 3 (as it returns), so that a larger number of light beams are associated with the attenuation of the amount of light. Since it is necessary to increase the amount of light to be emitted as it approaches the incident end surface portion 3 in order to emit from the emission surface (surface portion 8), the quantity or area of the light deflection element 13 increases as the distance from the incident end surface portion 3 increases. Uniform outgoing light can be obtained.
In FIG. 3, a gentle first inclined surface portion 6 and a sharp second inclined surface portion 7 facing the direction opposite to the incident end surface portion 3 (anti-incident end surface portion 4) on the back surface portion 5 of the light guide plate 2 are illustrated. Although not shown, the back surface portion 5 is illustrated as one gentle inclined surface so that the overall shape and the like can be easily understood.

  Actually, as shown in FIG. 2, the back surface portion 5 of the light guide plate 2 (2 </ b> A) has a gentle first inclined surface portion 6 and a sharp first surface facing the direction opposite to the incident end surface portion 3 (the anti-incident end surface portion 4). The two inclined surface portions 7 are formed in a staircase shape that is continuously connected alternately. Moreover, these surfaces are mirror surfaces.

  Therefore, the light guide plate 2 has a substantially wedge shape, and has a stepped shape in which the gentle first inclined surface portion 6 and the sharp second inclined surface portion 7 facing the counter incident end surface portion 4 are alternately and continuously connected. However, there is no light beam that breaks the critical angle while the incident light Ln1 from the incident end surface portion 3 travels to the counter incident end surface portion 4 located on the opposite side of the incident end surface portion 3, and the gentle second of the front surface portion 8 and the rear surface portion 5 The first inclined surface portion 6 or the sharp second inclined surface portion 7 repeats total reflection, reaches the anti-incident end surface portion 4, undergoes total reflection at the anti-incident end surface portion 4, and the totally reflected light beam Ln2 is again directed to the incident end surface portion 3. Proceed to At this time, the taper leak hardly occurs in the gentle first inclined surface portion 6, and even when it occurs, the light is emitted at a large emission angle along the back surface portion 5. Further, even when a taper leak occurs from the surface portion 8 due to total reflection at the gentle first inclined surface portion 6, the light is emitted at a large emission angle along the surface portion 8.

  However, since the light beam that has reached the sharp second inclined surface portion 7 is a light beam that is likely to cause a taper leak, it is totally reflected by the second inclined surface portion 7 and the light beam Ln3 proceeds in the direction of the surface portion 8, The light beam Ln4 can be emitted from the portion 8 at a substantially right angle.

  In addition, since the inclination angle of the second inclined surface portion 7 is set to 90 ° or less and more than twice the inclination angle of the first inclined surface portion 6, the light ray Ln4 is emitted from the surface portion 8 at a substantially right angle as described above. Or a viewing angle depending on the magnification with respect to the inclination angle of the first inclined surface portion 6 in order to obtain a range in which the first inclined surface portion 6 emits light at an emission angle that is approximately twice the emission angle due to the taper leak due to the gentle inclination angle of the first inclined surface portion 6. It is possible to freely control the emission angle such as.

  As described above, many light rays are totally reflected on each surface of the light guide plate 2, and the angle at which the light is totally reflected by the front surface portion 8 and the back surface portion 5 changes to a larger angle toward the incident end surface portion 3, and is reflected on the anti-incident end surface portion 4. When the light beam that has reached the anti-incident end face portion 4 travels again in the direction of the incident end face portion 3, there are many light rays that break the critical angle or near the critical angle at the surface portion 8. When it reaches 13, the critical angle is broken and emitted from the light guide plate 2, and at the back surface portion 5, there are many light rays that break the critical angle at the first inclined surface portion 6, light rays close to the critical angle, and the like. When the deflection element 13 is reached, the critical angle is broken and the light can be emitted from the light guide plate 2.

  Further, the second inclined surface portion 7 can totally reflect light with a large deflection angle even if it is not a light beam close to the critical angle, and can emit substantially vertical light or a wide range of light directly from the surface portion 8. For this reason, taper leak does not occur in the vicinity of the incident end face 3, so that even in the light source 10 having strong directivity, the shape of the light source 10 such as the emitted light with the light intensity near the incident end face 3 or the semiconductor light emitting element itself is changed from the exit face. There is no observation (reflection) or brightness spots.

  Furthermore, since a taper leak or the like can be caused only by a light beam totally reflected at the anti-incident end face portion 4, even in the case of the light source 10 in which the monochromatic light sources 10 such as RGB are arranged, the light does not immediately emit in the vicinity of the incident end face portion 3. Occurrence of luminescent color spots can be avoided. In addition, since the incident light is once totally reflected on the side opposite to the incident end face portion 3 of the light guide plate 2 and then emitted, it travels while repeating the total reflection several times in the meantime. Can be mixed to obtain complete white light.

  Further, even if the second inclined surface portion 7 is not a light ray close to the critical angle, it can be totally reflected and emitted directly from the surface portion 8 at a substantially right angle, and this substantially perpendicular emission light is incident on the incident end face portion 3 and the anti-incident end face. It can be emitted as a light beam having a sharp peak width by propagation in the direction of the portion 4 (here, Z direction).

  Further, even when there is a single light source 10, the light totally reflected by the anti-incident end surface portion 4 on the opposite side of the incident end surface portion 3 travels to the entire incident end surface portion 3 and is deflected as it proceeds in the direction of the incident end surface portion 3. Since the number or area of the light deflection elements 13 increases as the element 13 approaches the incident end face 3, uniform emitted light can be obtained at both ends of the incident end face 3, which are both ends of the light source 10.

When the light source 10 is single as described above, as shown in FIGS. 6 and 7, the anti-incident end surface portion 4 is centered on the same distance position from the two side surface portions 14, and is curved in the direction of the side surface portion 14. To form a Fresnel lens shape 4c. Thereby, the light that has entered the light guide plate 2 from the incident end face portion 3 repeats total reflection and proceeds to the anti-incident end face portion 4. When the light is reflected by the anti-incident end face portion 4 of the Fresnel lens shape 4c, the reflected light toward the incident end face portion 3 can be reflected as a parallel light beam because of the Fresnel lens shape 4c.
Therefore, the parallel reflected light beam from the anti-incident end surface portion 4 can uniformly travel to the first inclined surface portion 6, and the first inclined surface portion 6 is totally totally reflected from the exit surface of the light guide plate. Uniform outgoing light without spots can be obtained.

Further, FIG. 4 shows a schematic perspective view and FIG. 13 shows a light locus. A light ray L1 that continuously forms a convex ridge 4b and a concave ridge 4b ′ extending between the front surface portion 8 and the back surface portion 5 in the anti-incident end surface portion 4 and spreads in the direction of the side surface portion 14, Proceeding in the direction toward the anti-incident end face 4 while repeating total reflection at the side face 14. The light ray L2 is totally reflected at the inclined portion of the convex ridge 4b to become a reflected light beam L3, further totally reflected at the opposite inclined portion to become a reflected light beam L4, and can be returned in the direction of the incident end face portion 3, While returning, it can reach the first inclined surface portion 6, proceed in the direction of the surface portion 8, and exit to the outside.
Similarly, when the convex ridge 4b (concave ridge 4b ′) extending between the front surface portion 8 and the back surface portion 5 is partially formed as shown in FIG. For example, when the light source is provided only at the center of the incident end surface portion 3, the convex ridge 4b is provided more at the central portion of the non-incident end surface portion 4, and the convex ridge 4b is provided less toward the side surface portion 14. Can be reflected in the both end directions of the incident end face part 3.
Thus, the light can be dispersed in the direction of the side surface portion 14 by the convex ridge 4b and the concave ridge 4b ′.

Moreover, as shown to Fig.14 (a)-(f), the cross section of ridges, such as these convex ridges 4b and concave ridges 4b ', is shown. 14b1 in FIG. 14 (a) has a straight inclined surface, 4b2 and 4b3 in FIGS. 14 (b) and 14 (c) have circular arcs, 4b2 has a concave arc shape, and 4b3 has a convex shape. Even if the light guide plate 2 has an arc shape and has a wide width in the direction of the side surface portion 14 or the point light source 10 at the center of the incident end surface portion 3, it is possible to obtain reflected light having a larger spread. .
Furthermore, in 4b4, 4b5, and 4b6 in which the tops of the triangles or ridges such as 4b1, 4b2, and 4b3 in FIGS. 14 (a) to 14 (c) are cut flat, the inclined surface is similar to the above, but the flat portion Thus, the light can be reflected in the direction that has entered the anti-incident end face portion 4.
Therefore, it is possible to obtain uniform emission light without spots from the emission surface (surface portion 8) of the light guide plate 2 without being caught by the shape of the light source 10 or the light guide plate 2.

FIG. 8 is a view in which the direction of the side surface 14 of the anti-incident end surface 4 is an arc shape 4d.
By making the anti-incident end face portion 4 into an arc shape 4d, the light directed from the incident end face portion 3 toward the anti-incident end face portion 4 obtains light condensing characteristics by the arc shape 4d on the reflected light at the anti-incident end face portion 4. Therefore, for example, in the case of a plurality of point light sources 10 and the like, the reflected light from the light source 10 is mixed with each other while being difficult to leak from the side surface portion 14 direction.
Therefore, uniform outgoing light without spots can be obtained from the outgoing surface (surface portion 8) of the light guide plate 2.

  Although not shown, when the anti-incident end surface portion 4 has an arc shape in the thickness direction between the front surface portion 8 and the back surface portion 5, the reflected light is reflected in the thickness direction at the anti-incident end surface portion 4. Since the light condensing property can be obtained, the light can be condensed in the direction of the first inclined surface portion 6 and the second inclined surface portion 7 without waste, so that bright emitted light can be obtained.

Furthermore, as shown in FIG. 9, when the anti-incident end face portion 4 has a thickness direction between the front surface portion 8 and the back surface portion 5 and the side surface portion 14 has an arc shape 4d2, the role of a so-called toric lens 4d2 is obtained. Can do.
Therefore, since one light source 10 has two focal points, the light existing inside the light guide plate 2 can be used without waste.

Further, in FIG. 10, the anti-incident end face part 4 has an inclined face part 4f in the front face part 8 direction (thickness direction) and an inclined face part 4g in the rear face part 5 direction (thickness direction).
The light traveling from the incident end surface portion 3 toward the non-incident end surface portion 4 reflects the reflected light reflected by the inclined surface portion 4f toward the back surface portion 5 toward the first inclined surface portion 6 or the second inclined surface portion 7, The second inclined surface portion 7 or the like can proceed toward the emission surface (surface portion 8) and can be emitted to the outside.
Further, as shown in the light trajectory shown in FIG. 12, the light beam Ln1 from the incident end face portion 3 toward the non-incident end face portion 4 is reflected by the inclined surface portion 4g once, and the reflected light Ln22 reflected by the inclined surface portion 4g is inclined again. Proceeding to the inclined surface portion 4f facing the surface portion 4g, reflected again by the inclined surface portion 4f, the reflected light Ln2 proceeds in the direction of the second inclined surface portion 7, and the light beam Ln3 reflected by the second inclined surface portion 7 is emitted from the output surface (surface The light beam Ln4 is emitted to the outside from the emission surface (surface portion 8).
For this purpose, the emission angle from the emission surface (surface portion 8) is controlled by preventing banding phenomenon such as dark lines and bright lines, or by controlling the angle of reflection in the direction of the first inclined surface portion 6 and the second inclined surface portion 7. Can be controlled.

Further, as shown in FIG. 15, a corner cubic shape 4e having a shape obtained by cutting an end portion of a one-dot chain line cube is formed. Then, as shown in FIG. 11, the corner cubic shape 4 e is finely provided on the anti-incident end surface portion 4.
As shown in FIG. 15, the corner cubic shape 4 e is a triangular pyramid shape having the same sides and angles, and the light beam directed to the corner cubic shape 4 e has a property of returning to the original direction.
When the anti-incident end face portion 4 has a fine corner cubic shape 4e, for example, when the light guide plate 2 is a plurality of point light sources 10, the light from the plurality of light sources 10 is incident within the fine corner cubic shape 4e. Since the reflection is in the same direction, the light traveling from the direction of the incident end surface portion 3 is mixed in the light guide plate 2 when reflected by the counter-incident end surface portion 4 and returns to the direction of the incident end surface portion 3. Further, since the light is reflected in the direction of the emission surface by the second inclined surface portion 7, it is possible to obtain emission light having a spread from the emission surface.

Although not shown, in the case of the flat illumination device 1 having a large screen size, the light guide plate 2 has a structure in which the incident end surface portions 3 are provided on both opposite end surfaces of the light guide plate 2. The distance (thickness of the light guide plate 2) to the back surface portion 5 is minimum (thin) at the incident end surface portion 3, and the distance (thickness) is maximum (thick) at the center from the incident end surface portions 3 at both ends. It has such a shape.
That is, although not shown, the flat illumination device 1 has two light sources 10 in the vicinity of opposite end faces of the light guide plate 2, and the thickness of the light guide plate 2 facing the two light sources 10 is increased, and at the center portion. The distance between the front surface portion 8 and the back surface portion 5 directed toward the center is maximized.

  Therefore, the thickness of the light guide plate 2 increases as the thickness (distance between the front surface portion 8 and the back surface portion 5) increases from the two incident end surface portions 3 to the opposite side of each incident end surface portion 3. Since the shape is such that the center position of each incident end face portion 3 is thickest to the maximum, even if the light guide plate 2 is tapered while the incident light from each incident end face portion 3 proceeds to the center, the distance from the center to each other is reduced. There is no light beam that breaks the critical angle α, and light beams that have undergone total reflection on the front surface portion 8 and the back surface portion 5 are totally reflected in the light guide plate 2 facing each other and the incident end surface portions 3 facing each other, and enter each other again. When the light beam travels in the direction of each incident end face 3, the light deflecting element 13 can refract the light to break the critical angle α and emit the light from the surface 8.

  Although not shown, when only one light source 10 composed of a semiconductor light emitting element (LED or the like) is provided at the center of the incident end face 3, the light source 10 is a semiconductor light emitting element or the like, so that the light beam is reflected within a narrow range. While traveling in the direction of the incident end face 4, there is no light beam that breaks the critical angle α while traveling from the incident end face 3 toward the anti-incident end face 4, and the light Ln is totally reflected by the anti-incident end face 4. The critical angle α is broken while proceeding again in the direction of the incident end face portion 3, and the light deflecting element 13 provided on the surface portion 8 causes the light near the critical angle α to be refracted by the inclined surface of the light deflecting element 13, so Light can be emitted to the surface portion 8. Thereby, a dark part cannot be formed in the both ends of the incident end surface part 3, and uniform and bright emitted light can be obtained.

  Thus, the light guide plate 2 of the present invention is configured such that the thickness of the light guide plate 2 is the thinnest at the position of the incident end surface portion 3 and the thickness of the light guide plate 2 increases as the distance from the incident end surface portion 3 increases. In addition, the back surface 5 has a stepped shape in which a gentle first inclined surface portion 6 and a sharp second inclined surface portion 7 facing in the opposite direction to the incident end surface portion 3 are alternately connected, and these surfaces are mirror surfaces. In addition, a fine light deflection element 13 is provided on the front surface 8 and / or the back surface 5. For this reason, there is no light beam that breaks the critical angle while the light beam guided from the incident end surface part 3 into the light guide plate 2 travels to the anti-incident end surface part 4 located on the opposite side of the incident end surface part 3. Many light rays are totally reflected on the surface, and the angle of total reflection on the front surface portion 8 and the back surface portion 5 changes to a larger angle toward the anti-incident end surface portion 4, and the light rays reflected on the anti-incident end surface portion 4 are incident again. When a light beam that is deflected by the first inclined surface portion 6 when traveling in the direction of the end surface portion 3 and breaks the critical angle at the surface portion 8 or a light beam that is close to the critical angle is present, the fine light deflection element 13 is reached together with the taper leak. The critical angle is broken and the light is emitted from the light guide plate 2. The second inclined surface portion 7 can totally emit light directly from the surface portion 8 even if it is not a light ray close to the critical angle. In particular, the light totally reflected by the second inclined surface portion 7 can obtain substantially vertical outgoing light.

  Therefore, the amount of light can be controlled, the light source is not reflected, and both ends of the incident end surface portion 3 in the vicinity of the incident end surface portion 3 have no dark portions, and bright and uniform emitted light can be obtained. As a result, the area of the light guide plate 2 that can be actually used can be increased, and even if the light sources 10 are provided in parallel (array form), the light from the adjacent light sources 10 does not overlap with each other. Occurrence can be prevented. Further, when the light guide plate is enlarged, the opposite end faces are the incident end face portions 3 and the thickness of the central portion is the thickest, so that the light guide plate 2 is excellent in mechanical stability and strength.

  The light source 10 is a semiconductor light emitting element, and is composed of an LED, a laser, or the like, and each RGB (red, green, blue) monochromatic light is provided in the vicinity of the incident end face 3 or RGB (red light emission, green light emission, blue color). A unit configured in an array shape in which a plurality of semiconductor light emitting elements composed of (light emission) are combined may be provided on the incident end face 3. In particular, in the case where high luminance is required as the light source 10, a high-luminance light emitting element of a quaternary compound or a compound such as InGaAlP, InGaAlN, or InGaN is used.

  Furthermore, as the light source 10, white light may be obtained using a semiconductor light emitting element and a wavelength conversion material. For example, a wavelength conversion material (YAG system) that is excited by blue light emitted from an InGaAlN-based semiconductor light-emitting element and emits light in yellow, orange, or the like is provided. The light source 10 in which the emission color mixed with the emission color such as orange becomes white may be used.

The light source 10 may use CCFLs (cold cathode fluorescent lamps) when the incident end face portion 3 is large or the light guide plate 2 itself is large. These light sources 10 are linear, and direct light is incident on the incident end face of the light guide plate 2. The light enters the light guide plate 2 from the portion 3, and other light enters the light guide plate 2 through the space between the light source 10 and the reflector while being reflected by a reflector (not shown).
In the case of this linear light source 10, a bright line with high luminance appears in the vicinity of the incident end face 31 in the conventional light guide plate 21, but generation of a bright line by using the light guide plate 2 of the present invention. Can be prevented.

Although not shown, the reflector 11 has a reflective surface having an uneven shape or a prism shape, and metal such as aluminum is deposited on a sheet of thermoplastic resin mixed with a white material such as titanium oxide or a sheet of thermoplastic resin. It consists of the thing which gave or laminated | stacked metal foil, and a sheet-like metal. The reflector 11 covers a portion other than the incident end face portion 3 and the surface portion 8, reflects or irregularly reflects light other than the light from the light source 10 emitted to the surface portion 8 by the light guide plate 2, and enters the light guide plate 2 again. Thus, all the light from the light source 10 is emitted from the surface portion 8.
Further, the position of returning to the inside of the light guide plate 2 is controlled by controlling the concave and convex shape and the prism shape of the reflector 11 used for the anti-incident end face part 4 and the back face part 5, and the luminance, light quantity distribution and outgoing light of the final outgoing light are controlled. Corners etc. can be adjusted.

  Furthermore, since the reflecting surface of the reflector 11 has an uneven shape or a prism shape, the light source 10 can mix light of three primary colors such as RGB within the light guide plate 2 by reflection by the prism surface. The efficiency of converting light from the light source 10 to the light emitted from the light guide plate 2 can be improved without wasting light.

  The lenticular lens body 12 is formed of PET (polyethylene terephthalate), acrylic resin (PMMA), polycarbonate (PC), or the like. The lenticular lens body 12 shown in FIG. 1 has a large number of micro cylindrical lenses (half surfaces) arranged in parallel, has the same semicircular cross section from the incident end surface portion 3 to the anti-incident end surface portion 4, and the incident end surface portion 3. The light emitted from the light guide plate 2 (2A) is condensed.

  Further, the lenticular lens body 12 shown in FIG. 16 to be described later has a semicircular cross section in which the size of the cross section increases as the distance from the incident end face portion 3 increases, and a large number of lenticular lens bodies 12 are arranged radially from the incident end face portion 3. The light emitted from the light guide plate 2 (2B) is collected.

  Although not shown here, for example, when the directivity of the light source 10 such as CCFL (cold cathode fluorescent lamp) indicates the radial direction, a reflector is provided around the light source 10 (CCFL) to The incident end face 3 and the light source 10 are surrounded, the light from the light source 10 is reflected, and the reflected light is incident again on the incident end face 3 of the light guide plate 2. The reflector can be made of a white insulating material or a sheet or metal deposited with a metal such as aluminum.

  Next, another example of the light guide plate 2 and the flat illumination device 1 of the present invention is shown in FIG. The flat illumination device 1 (1B) shown in FIG. 16 includes a directional light source 10 in the vicinity of one end corner of the light guide plate 2 (2B). An incident end face portion 3 is provided at one end of the light guide plate 2B having a thin rectangular cubic shape, and the distance between the front surface portion 8 and the back surface portion 5 (thickness of the light guide plate 2b) is the incident end face portion 3. The distance between the incident end face part 3 and the rear end part 5 is the opposite end corner to the incident end face part 3. The gentle first inclined surface portions 6 and the sharp second inclined surface portions 7 facing in four directions are alternately and continuously connected to form a staircase shape radially from the incident end surface portion 3.

  Further, the gentle first inclined surface portion 6 and the sharp second inclined surface portion 7 that form the above-mentioned step shape form a mirror surface, and a fine light deflection element 13 is provided on the surface portion 8 of the light guide plate 2B.

  Further, the lenticular lens body 12 is formed radially from the incident end surface 3 centering on the incident end surface 3 of the light guide plate 2B (on the outside extension line of the incident end surface 3) on the upper side of the light exit surface (surface portion 8) of the light guide plate 2B. Is provided. Further, the light guide plate 2 </ b> B includes a reflector 11 having reflectivity that covers a portion other than the incident end surface portion 3 and the emission surface (surface portion 8).

  Here, the action and effect of light are the same as described above, and since they have been described above, they are omitted here. However, in the light guide plate 2A in FIG. 1 and FIG. 2, it was the effect of light in the mutual direction of the incident end face portion 3 and the anti-incident end face portion 4, but in the light guide plate 2B and the flat illumination device 1B in FIG. The light source 10 and the incident end surface portion 3 are centered on two side surfaces sandwiching the incident end surface portion 3 in a radial direction, and the two side surfaces sandwich the end corner 4 having the maximum separation distance from the incident end surface portion 3 from the two side surfaces. This is a lenticular lens body 12 having a different reflection action and corresponding to the light emitted from the light guide plate 2B.

  Incidentally, the staircase shape of the light guide plate 2B shown in FIG. 16 can be any one of the shapes shown in FIGS. Note that, in FIGS. 17A to 17C, the staircase-shaped boundary line is indicated by a one-dot chain line. The staircase shape in the example of FIG. 17A is formed on the incident end surface 3 at the corner of the light guide plate 2B so that the boundary line intersects substantially perpendicularly on the virtual line L connecting the incident end surface 3 and the end corner 4. It is connected in a straight line from the side surfaces of both ends to be connected. And between each boundary line of staircase shape is equal intervals. The step shape in the example of FIG. 17B is connected in a circular arc shape from both side surfaces connected to the incident end surface portion 3 at the corner of the light guide plate 2B with the incident end surface portion 3 as the center. And between each boundary line of staircase shape is equal intervals. The stepped shape in the example of FIG. 17C has the incident end surface portion 3 at the corner of the light guide plate 2B so that the boundary line intersects the virtual line L connecting the incident end surface portion 3 and the end corner 4 at a substantially right angle. It is connected in a straight line from the side surfaces on both ends connected to the. And between each boundary line of staircase shape is equal intervals. When the light guide plate 2 shown in FIGS. 16 and 17A to 17C is large (the distance from the incident end face 3 is long), the distance between the boundary lines becomes longer as the distance from the incident end face 3 increases. It is preferable to do this.

  Here, since the action and effect of these lights are the same as those described with reference to FIGS. 1 to 3, the description thereof will be omitted, but the lenticular lens body 12 is also guided in the flat illumination device 1 of FIG. The thing of the shape (shape shown to Fig.17 (a)-(c)) corresponding to the emitted light from the optical plate 2 is used.

  By the way, as shown in FIGS. 17D to 17F, the light guide plate 2 of this example may be configured by combining four light guide plates 2B shown in FIGS. 17A to 17C described above. it can. In the example of FIG. 17D, the four light guide plates 2B shown in FIG. 17A are combined so as to coincide with each other at the four end corners 4, and a staircase shape is formed on the imaginary line L connecting the respective incident end face portions 3. The corners of the boundary line are positioned and the staircase shape is formed in a concentric rectangular shape. And between the boundary lines of the concentric rectangular shape centering on the end corner 4, there is an equal interval. In the example of FIG. 17 (e), the four light guide plates 2B shown in FIG. 17 (b) are combined so as to coincide with each other at the four end corners 4, and the step shape is formed concentrically with the end corners 4 as the center. . And between the concentric boundary lines centering on the end corner 4, there is an equal interval. In the example of FIG. 17 (f), the four light guide plates 2 B shown in FIG. 17 (c) are combined so as to coincide with each other at the four end corners 4, and are approximately perpendicular to the imaginary line L connecting the incident end face portions 3. Thus, the straight portion of the staircase shape is located and the staircase shape is formed in a concentric rectangular shape. And between the boundary lines of the concentric rectangular shape centering on the end corner 4, there is an equal interval.

  When the light guide plate 2 shown in FIGS. 17D to 17F is large (the distance from the incident end face 3 is long), the distance between the boundary lines is increased as the distance from the incident end face 3 increases. preferable. For example, in the case of the light guide plate 2 </ b> B of FIG. 17D, the distance between the concentric rectangular boundary lines centering on the end corner 4 is shortened from the end corner 4 toward the four incident end face portions 3.

  Here, when any one of the light guide plates 2B shown in FIGS. 17D to 17F described above is employed, the light source 10 is provided in the vicinity of the incident end surface portion 3 at each of the four corners, and the light guide plate 2B is disposed above the light guide plate 2B. The one corresponding to the shape of the four light guide plates 2B (the shape in any one of FIGS. 17A to 17C) to be used is also used.

  Thus, in the light guide plate 2 and the flat illumination device 1 of the present invention, the thickness of the light guide plate 2 is the thinnest at the position of the incident end surface portion 3, and the thickness of the light guide plate 2 increases as the distance from the incident end surface portion 3 increases. By being configured in this way, when traveling in the direction from the incident end face 3 toward the opposite incident end face 4 located on the opposite side of the incident end face 3 (hereinafter referred to as the forward direction), more total reflection is performed on the mirror surface of each surface of the light guide plate 2. After reaching the anti-incident end face portion 4 and performing total reflection at the anti-incident end face portion 4, the process proceeds again in the direction of the incident end face portion 3 (hereinafter, reverse direction). Since the thickness of the light guide plate 2 is gradually reduced when proceeding in the reverse direction, there are many light rays that are deflected by the first inclined surface portion 6 and break the critical angle at the surface portion 8 or light rays close to the critical angle. The critical angle is broken when the light deflecting element 13 is reached together with the leak, and is emitted from the light guide plate 2, and the second inclined surface portion 7 has a larger deflection angle even if it is not a light beam close to the critical angle. , The incident angle to the surface portion 8 becomes small, and the light can be directly emitted from the surface portion 8. In particular, the light totally reflected by the second inclined surface portion 7 can obtain substantially vertical outgoing light.

  Further, the light deflection element 13 provided so that the amount of distribution increases as it approaches the incident end face portion 3 of the surface portion 8, so that the light beam near the critical angle α causes refraction by the inclined surface of the light deflection element 13, and more A light beam is emitted to the surface portion 8, and uniform and high-luminance outgoing light can be obtained.

  Similarly, when the incident end surface portions 3 are provided at both ends of the light guide plate 2, the thickness of the light guide plate 2 is the thinnest at the position of the incident end surface portion 3, and the thickness of the light guide plate 2 is the central portion of the light guide plate 2. Because of the thickest configuration, only the total reflection is obtained at the mirror surface of each surface in the forward direction, and the thickness of the light guide plate 2 gradually increases from the position beyond the center and from the position beyond the center in the reverse direction. The light beam breaks the critical angle while the light beam travels, and is emitted from the surface portion 8, and the light beam near the critical angle α is provided by the light deflection element 13 provided so that the amount of distribution increases as it approaches the incident end surface portion 3 of the surface portion 8. However, the inclined surface of the light deflecting element 13 causes refraction and the like, and more light rays are emitted to the surface portion 8, and uniform and high-luminance outgoing light can be obtained. Moreover, since the second inclined surface portion 7 has a large deflection angle even if it is not a light beam close to the critical angle, the angle of incidence on the surface portion 8 becomes small when total reflection is performed, and the light is emitted directly from the surface portion 8. can do.

  Therefore, in the vicinity of the incident end face portion 3, light that is directly bright from the light source 10, that is, so-called reflection is not emitted, and light that is bright and free of spots is emitted on the entire light guide plate 2. In particular, when the incident end face portions 3 are provided at both ends of the light guide plate 2, the mechanical strength is excellent, and a substantially large exit surface can be secured as much as there is no reflection. Even when the light source 10 uses the three primary color lights (RGB) as the white light source 10, it does not emit near the incident end face 3, so that each color (RGB) light beam mixes and breaks the critical angle α while traveling in the forward direction. Sometimes it can be emitted as perfect white light.

  Further, when only one directional light source 10 such as a semiconductor light emitting element is provided at the center of the incident end face 3, the light beam travels in the direction toward the non-incident end face 4 in a narrow range. Although both end portions of the incident end surface portion 3 become dark portions, there is no light beam that breaks the critical angle α while traveling from the incident end surface portion 3 toward the anti-incident end surface portion 4, and the anti-incident end surface portion 4 While the light beam Ln is reflected and travels again in the direction of the incident end face portion 3, the critical angle α is broken, and the light deflection element 13 provided on the surface portion 8 causes the light beam near the critical angle α to be reflected by the inclined surface of the light deflection element 13. A larger number of light rays can be emitted to the surface portion 8 by causing refraction and the like. For this reason, dark portions cannot be formed at both end portions of the incident end surface portion 3, and uniform and bright outgoing light can be obtained.

  As described above, in the light guide plate of the present invention, the thickness of the light guide plate is such that the incident end surface portion is the minimum thickness, and the light guide plate is made thicker as the distance from the incident end surface portion increases, and the back surface portion has a gently inclined surface. And a second inclined surface portion that is sharper than the first inclined surface portion (more than twice the inclination angle of the first inclined surface portion). These are connected to each other alternately and formed into a staircase shape, and the light guide plate and the lenticular lens body are provided to constitute a flat illumination device.

  Suitable for backlights such as small liquid crystal display devices and backlights such as large liquid crystal display devices. Particularly, it is possible to obtain emitted light with high brightness and no luminance spots or color temperature spots. For example, it is possible to provide a light guide plate and a flat illumination device ranging from a mobile product to a general-purpose product such as a liquid crystal television to a special purpose.

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 view and a locus diagram showing an example of a light guide plate according to the present invention. It is the partial schematic sectional drawing and locus | trajectory figure of the light-guide plate which concerns on this invention. It is a schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic plan view which shows the other example of the light-guide plate which concerns on this invention. It is a partial schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic plan view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is a schematic perspective view which shows the other example of the light-guide plate which concerns on this invention. It is the schematic sectional drawing and locus diagram which show the other example of the light-guide plate which concerns on this invention. It is the schematic plan view and locus diagram which show the other example of the light-guide plate which concerns on this invention. (A)-(f) It is the elements on larger scale which show each example of the convex ridge provided in the light-guide plate which concerns on this invention, or a concave ridge. It is explanatory drawing which concerns on this invention. It is a schematic perspective view which shows the other example of the planar illuminating device which concerns on this invention. (A)-(f) It is the schematic plan view seen from the back surface part side which shows the other example of the light-guide plate which concerns on this invention. 1 is a schematic view of a conventional light guide plate. (A), (b) It is schematic drawings of the conventional light-guide plate. 1 is a schematic view of a conventional light guide plate and the like.

Explanation of symbols

1 (1A, 1B) Flat illumination device 2 (2A, 2B) Light guide plate 3 Incident end face 4 Anti-incident end face 4b Convex ridge 4b 'Concave ridge 4b1, 4b2, 4b3 Inclined surface 4b4, 4b5, 4b6 Flat top 4c Fresnel shape 4d Arc shape 4d2 Toric lens 4e Corner cubic shape 4f, 4g Inclined surface portion 5 Back surface portion 6 First inclined surface portion 7 Second inclined surface portion 8 Surface portion 9 Light source 10 Light source 11 Reflector 12 Lenticular lens body 13 Light deflection Element 14 Side surface portion 21 Light guide plate 31 Incident end surface portion 41 Non-incident end surface portion 61 Front surface portion 71 Back surface portion L Virtual line L1, L2, L3, L4, Ln1, Ln2, Ln3, Ln4, Lo, Lo1, Lo2, Lo3, Lo4 , Ln22 Ray γ Refraction angle n Refractive index α Critical angle

Claims (13)

A light guide plate having an incident end face portion that guides light having directivity, a front surface portion that emits the light, and / or a back surface portion, and a side surface portion that intersects the front surface portion and the back surface portion,
The distance between the front surface portion and the back surface portion is such that the distance between the front surface portion and the back surface portion gradually increases with increasing distance from the incident end surface portion. The distance between the front surface portion and the back surface portion is maximized at the anti-incident end surface portion which is the smallest at the incident end surface portion and is the maximum separation distance from the incident end surface portion, and the back surface portion formed of a mirror surface is When a gradual shape is formed in which a gentle first inclined surface portion and a sharp second inclined surface portion facing in the opposite direction to the incident end surface portion are alternately connected, and when proceeding from the incident end surface portion to the counter incident end surface portion Without breaking the critical angle, the first inclined surface portion breaks the critical angle when reflected from the anti-incident end surface portion and proceeds from the anti-incident end surface portion to the incident end surface portion, thereby generating a taper leak and the second inclination. Total reflection by face A light guide plate, wherein the reflection angle is emitted substantially perpendicular angle smaller. A light guide plate having an incident end face portion that guides light having directivity, a front surface portion that emits the light, and / or a back surface portion, and a side surface portion that intersects the front surface portion and the back surface portion,
A thin plate-like rectangular cube is formed, and the front end portion and / or the back surface portion is provided with a fine dot-shaped light deflecting element so that the quantity or area increases as it approaches the incident end surface portion, and the incident end surface The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the surface portion increases. The distance between the front surface portion and the back surface portion is maximized at the anti-incident end surface portion that is the maximum separation distance from the portion, and the back surface portion formed of a mirror surface is a gentle second surface facing in the opposite direction to the incident end surface portion. The first inclined surface portion and the sharp second inclined surface portion are formed in a staircase shape alternately and continuously, and when proceeding from the incident end surface portion to the anti-incident end surface portion, the critical angle is not broken, and the anti-incident end surface portion is formed. The anti-incident end face portion is reflected by Then, the first inclined surface portion breaks the critical angle to generate a taper leak when proceeding to the incident end surface portion, and the second inclined surface portion emits at a substantially vertical angle with a small reflection angle of total reflection. the light guide plate you characterized by emitting defeating critical angle by the inclined surface of the optical deflector element also when proceeding to the reaction incidence end face direction from parts. The second inclined surface is claim 1 or 2, wherein the light guide plate, wherein the inclination angle is less than 90 ° at least twice the inclination angle of the first inclined surface portion. The anti-incident end surface portion is centered on the same distance from the two side surface portions, and has a Fresnel lens shape whose curvature changes in the direction of the side surface portion or a convex shape extending between the front surface portion and the back surface portion. and claim 1 or 2, wherein the light guide plate and forming a concave edge. 5. The light guide plate according to claim 4, wherein the convex ridge and the concave ridge are formed such that a slope of a cross section is a straight or arcuate triangular shape or a top portion of the ridge is notched flat. 3. The light guide plate according to claim 1, wherein the anti-incident end surface portion has an arc shape in a thickness direction of the front surface portion and the back surface portion and / or the side surface portion direction. The anti-incident end face portion, claim 1, characterized in that it has a slope portion on the surface portion direction and / or the back portion direction, 2, the light guide plate according to any one of 4,6. The anti-incident end face portion, claim 1 or 2, wherein the light guide plate and having a fine corner cubic shape. A directional light source;
A thin plate-like rectangular cube shape having an incident end face portion for guiding light from the light source, a front surface portion and / or a back surface portion for emitting the light, and a side surface portion intersecting the front surface portion and the back surface portion is formed. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the front surface portion and the back surface portion gradually increases as the distance from the incident end surface portion increases. The distance between the front surface portion and the back surface portion is maximum at the counter-incident end surface portion that is the maximum separation distance from the incident end surface portion, and the back surface portion formed of a mirror surface is in the opposite direction to the incident end surface portion. The first inclined surface portion and the sharp second inclined surface portion facing each other in a staircase shape alternately connected, and when proceeding from the incident end surface portion to the anti-incident end surface portion, the critical angle is not broken, Reflected by the anti-incident end face and the anti-incident A light guide plate for emitting a substantially normal angle reflection angle is small of the total reflection by the second inclined surface portion as well as generating a tapered leak defeating critical angle by the first inclined surface when the surface proceeds to the incident end face ,
A planar illumination device comprising: a reflector having reflectivity that covers a portion other than the incident end surface portion and the emission surface of the light guide plate. A directional light source;
A thin plate-like rectangular cube shape having an incident end face portion for guiding light from the light source, a front surface portion and / or a back surface portion for emitting the light, and a side surface portion intersecting the front surface portion and the back surface portion is formed. The surface portion and / or the back surface portion is provided with fine dot-shaped light deflecting elements so that the quantity or area increases as the distance from the incident end surface portion increases, and the surface portion increases as the distance from the incident end surface portion increases. The distance between the front surface portion and the back surface portion is minimized at the incident end surface portion so that the distance between the back surface portion and the back surface portion gradually increases, and is the maximum separation distance from the incident end surface portion. The distance between the front surface portion and the back surface portion is maximized at the anti-incident end surface portion, and the back surface portion formed of a mirror surface has a gentle first inclined surface portion and a sharp first surface facing in the opposite direction to the incident end surface portion. The two inclined surface parts are connected alternately. When connecting from the incident end face part to the anti-incident end face part, the critical angle is not broken and reflected from the anti-incident end face part and going from the anti-incident end face part to the incident end face part. A light guide plate that breaks a critical angle by the first inclined surface portion and generates a taper leak and emits light at a substantially vertical angle with a small reflection angle of total reflection by the second inclined surface portion;
A flat illumination device comprising: a reflector having reflectivity that covers a portion other than the incident end surface portion and the emission surface of the light guide plate. The flat illumination device according to claim 9 or 10 , further comprising a lenticular lens body at an upper portion on an emission surface side of the light guide plate. The light source is composed of a directional semiconductor light emitting element, and is composed of monochromatic light, red light, green light, blue light, or white light using a wavelength conversion material, and is configured as a single element or an array. The flat illumination device according to claim 9 or 10, characterized in that The reflector plane illumination device according to claim 9 or 10, wherein the reflecting surface is uneven or prism shape.

Images