JP4648358B2 - Light guide plate and flat illumination device - Google Patents

Description

  The present invention relates to a light guide plate and a flat illumination device used for a liquid crystal display device or the like, and for any light source, a continuous or continuous light source from a position corresponding to the luminance distribution or light energy distribution of the light source. An optical element having an inclined surface corresponding to the light bundle has a density distribution that increases functionally in proportion to the distance from the light source, so that even a small light source such as a directional point light source is bright, linear, etc. The present invention relates to a light guide plate and a flat illumination device that can obtain bright emitted light even with a light source having a directivity distribution and having a shape of.

Conventional light guide plates and flat illumination devices use a method that uses scattering on the back surface of the light guide plate. In this method, a dot or a rectangular shape is printed with an ink mixed with a white material such as titanium oxide as the distance from the light source increases, and scattered light is obtained as the distance from the light source increases. We are trying to obtain the uniformity of the emitted light.
Further, an injection molding method is used, in which scattering is used for the front surface portion and the back surface portion of the light guide plate, and a minute uneven shape is randomly formed.

  Similarly, as a light guide plate and a flat illumination device using an injection molding method, one using a method utilizing refraction or reflection on the front surface portion or the back surface portion of the light guide plate is known. In this method, the convex shape and the concave shape are simply formed so as to be distributed (gradation) more away from the light source, and the probability of refraction and reflection increases as the distance from the light source increases, and the light emitted from the light guide plate is made uniform. Yes.

Further, as a light guide plate and a flat illumination device using an injection molding method, one using a method using refraction or reflection on the front surface portion or the back surface portion of the light guide plate is also known. In this method, a prism shape is formed in parallel with the light source, and light rays from the light source are refracted or reflected by the sides of the prism to be deflected to the emission surface or emitted from the emission surface.
Similarly, a method is known in which a prism shape is provided in parallel with the light source on the front surface portion and the back surface portion of the light guide plate. In this method, the height or depth of the prism is set higher or deeper as the distance from the light source increases, the more light rays from the light source are received as the distance from the light source increases, and the reflected light or refractive light is used more. The emitted light is made uniform.

  Conventional light guide plates and flat illumination devices use a method of utilizing scattering on the back surface of the light guide plate, and the more the circular or rectangular shape is separated from the light source by using ink mixed with a white material such as titanium oxide. Many dots were printed, and scattered light was obtained as the distance from the light source was increased to obtain uniformity of light emitted from the light guide plate. However, the light was absorbed by the white material or ink, and the light was scattered. As a result, the light beam does not reach only the exit surface, and there is a problem in luminance because the absolute amount of emitted light is low.

  In addition, there is no loss due to light absorption in the method in which fine irregularities are randomly formed on the front and back surfaces of the light guide plate by injection molding, and the light from the light source is scattered. Are scattered, the light beam does not reach only the exit surface, the brightness of the exit light is low, and the uneven distribution is random, causing problems with brightness spots and the like.

  Similarly, when the distribution of the convex shape or concave shape increases as the distance from the light source is increased (gradation), it is improved compared to printing of ink or the like, or random shaping of fine uneven shapes, but it is merely away from the light source. The probability of refraction and reflection is only increased, and it does not correspond to the directivity (luminance distribution) of the light beam or the shape of the light source. There are no challenges.

  Furthermore, a method of forming a prism shape in parallel with the light source on the front surface portion and the back surface portion of the light guide plate, refracting or reflecting light rays from the light source on the sides of the prism and deflecting to the output surface, or emitting from the output surface, This is true if all of the prism ridge lengths have the same condition (in the case of a simple ideal state), but in reality, the light source directivity (luminance distribution) and the shape of the light source are not supported. There is a problem that the amount of light, directivity, and energy are not fully utilized.

  Similarly, a prism shape is provided on the front and back surfaces of the light guide plate in parallel with the light source, and the height and depth of the prism are set higher or deeper as the distance from the light source increases, and more light from the light source is received as the distance from the light source increases. Thus, a method that uses a lot of reflected light and refracted light to make the emitted light uniform regardless of the distance from the light source is good as a method away from the light source, but the prism itself is actually pointing the light source. However, there is a problem that the light amount, directivity, and energy of the light source are not sufficiently used because they are not compatible with the characteristics (luminance distribution) and the shape of the light source.

  In any case, these conventional methods do not correspond to the directivity of the light amount of the light source, the energy distribution, the shape of the light source, and the like, and these conventional methods are limited.

  The present invention has been made in order to solve the above-described problems. Compared to the conventional technique, the present invention always continuously corresponds to the light flux from the light source at a position corresponding to the directivity and energy distribution of the light amount from the light source. By providing an optical element having an inclined surface, total reflection or refraction is performed by the inclined surface of the optical element equivalent to continuity at a position where the luminance and energy from the light source are always equal, and the same luminance and energy are provided on the exit surface side. The product of the output light quantity and the output angle can be obtained at any position of the light guide plate so that the optical element density distribution can be increased in proportion to the distance from the light source as the luminance and energy from the light source are attenuated. An object of the present invention is to provide a light guide plate and a flat illumination device that can emit light equally.

  In addition, by continuously providing an optical element having an inclined surface corresponding to the light flux from the light source at a position corresponding to the directivity of the light amount from the light source and the energy distribution, the directivity and energy of the light amount from the light source are always provided. It is possible to emit the same brightness and energy to the exit surface side by performing the total reflection and refraction by the inclined surface of the equivalent optical element continuously at the same position, and the optical with the attenuation of the brightness and energy from the light source Provided is a light guide plate and a flat illumination device capable of increasing the element density distribution in proportion to the distance from the light source so that the product of the amount of light emitted at any position of the light guide plate and the solid angle can be emitted equally. There is.

The light guide plate according to claim 1 of the present invention includes an incident portion that guides light from an L-shaped light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, and these surfaces. In the light guide plate having the side surface portion connecting the back surface portion and the back surface portion, and having the two side surface portions to be connected as the incident portion, the front surface portion or the back surface portion has a position corresponding to the luminance distribution or light energy distribution of the light source. Two optical elements having an inclined surface corresponding to the light flux from the light source continuously have a density distribution that increases functionally in proportion to the distance from the L-shaped light source and are opposed to the L-shaped portion of the light source. In the vicinity of one corner to which the side surface is connected, the two side surfaces opposed to both end portions of the light source are separated from the side surface portion and one corner rather than the two side surface portions opposed to the linear portion of the light source. Tilting closer to the side than the two opposite sides A slope is provided facing the light source .

The light guide plate according to claim 1 includes an incident portion that guides light from an L-shaped light source, a front surface portion that emits the light, a back surface portion that is located on the opposite side of the front surface portion, and the front surface portion and the back surface. In the light guide plate having two side surfaces connected to each other, and the two side surfaces to be connected as the incident portion, the front surface or the back surface has a light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source. two of the side portions opposed to L-shaped portion of the light source which has a proportionally functionally density distribution that increases with the distance the optical element from the L-shaped light source having an inclined surface corresponding to the light beam from the In the vicinity of one corner where the two light sources are connected, the two side surfaces opposed to both end portions of the light source are opposed to the linear portion of the light source so that they are separated from the side surface and one corner rather than the two side surfaces opposed to the linear portion of the light source. Light the inclined surface so that it is closer to the side part than one side part. Since it is provided facing the light source, total reflection and refraction are always performed by the inclined surface of the continuous optical element at the position where the luminance and energy from the light source are equal, and the same luminance and energy are emitted to the emission surface side. can do. Moreover, the product of the amount of light emitted at every position of the light guide plate and the solid angle is equally emitted so that the optical element density distribution increases in proportion to the distance from the light source as the luminance and energy from the light source decrease. can do.

The light guide plate according to claim 2 includes an incident portion that guides light from an L-shaped light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, and these surface portions. In the light guide plate having a side surface portion connecting the back surface portion and the two side surface portions to be connected as the incident portion, the front surface portion or the back surface portion is continuously located at a position corresponding to the luminance distribution or light energy distribution of the light source. In particular, the optical element having an inclined surface corresponding to the light flux from the light source has a density distribution that increases functionally in proportion to the distance from the L-shaped light source and is opposed to the L-shaped portion of the light source. In the vicinity of one corner to which the side surface is connected, the two side surfaces facing both ends of the light source are opposed to the linear portion of the light source so that they are farther from the side surface and one corner than the two side surfaces facing the linear portion of the light source. The inclined surface is closer to the side surface than the two side surfaces Is provided facing the light source .

The light guide plate according to claim 2 includes an incident portion that guides light from an L-shaped light source, a front surface portion that emits the light, a back surface portion that is located on the opposite side of the front surface portion, and the front surface portion and the back surface. In a light guide plate having two side surfaces connected to each other and the two side surfaces to be connected as an incident portion, the front surface portion or the back surface portion is continuously located at a position corresponding to the luminance distribution or light energy distribution of the light source. two side portions of the optical elements having an inclined surface corresponding to the light beam facing the L-shaped portion of the light source and having a distance proportional functionally density distribution increasing from the L-shaped light from the light source In the vicinity of one corner where the two light sources are connected, the two side surfaces opposed to both end portions of the light source are opposed to the linear portion of the light source so that they are separated from the side surface and one corner rather than the two side surfaces opposed to the linear portion of the light source. The light source is inclined so that it is closer to the side part than one side part. Since it is facing and provided that always total reflection and refraction, etc. luminance and energy are equal position from the light source by the inclined surface of the continuous equivalent optical elements, a continuous equivalent brightness and energy on the exit surface side Can be emitted. Moreover, the product of the amount of light emitted at every position of the light guide plate and the solid angle is equally emitted so that the optical element density distribution increases in proportion to the distance from the light source as the luminance and energy from the light source decrease. can do. In addition, by controlling the length of the optical element and the interval between adjacent optical elements, the product of the amount of light emitted from the optical element and its solid angle is equal, but the optical element is lost. In other places, it is possible to obtain light energy lower than that of the optical element.

  Furthermore, the light guide plate according to claim 3 is characterized in that the cross section of the optical element has a triangular shape, a trapezoidal shape, or an arc shape, and is continuous or continuous.

  In the light guide plate according to claim 3, since the cross section of the optical element is triangular, trapezoidal, arc-shaped and continuous or continuous, the light rays entering the light guide plate from the incident portion of the light guide plate are triangular, The trapezoidal and arcuate inclined surfaces can exist at positions corresponding to the light flux from the light source. If these are continuous, the same luminance and energy can be emitted at any position, and the same luminance and energy can be emitted continuously at any position.

  The light guide plate according to claim 4 is characterized in that the height of the optical element is increased or / and partially raised or lowered as the optical element is moved away from the light source.

  In the light guide plate according to the fourth aspect, the height of the optical element is increased or / and partially raised or lowered as the optical element is moved away from the light source, so that even the optical element far from the light source receives light rays from the light source and performs total reflection. The amount of light emitted from the light guide plate and the angle of light emission can be changed by partially raising or lowering the height.

The light guide plate according to claim 5 is characterized in that the angle between the inclined surface and the front surface portion and the back surface portion is in the range of π / 2-2 · critical angle to critical angle.

  In the light guide plate according to claim 5, since the angle between the inclined surface and the front surface portion and the back surface portion is in the range of π / 2-2 · critical angle to the critical angle, from the maximum incident angle of the light beam guided into the light guide plate By using the range up to the minimum angle that breaks the critical angle, all the reflected light can break the critical angle.

  The light guide plate according to claim 6 is characterized in that an angle formed between the front surface portion and the back surface portion of the inclined surface in proportion to the distance from the light source approaches the critical angle.

  In the light guide plate according to the sixth aspect, the angle formed between the front surface portion and the back surface portion in proportion to the distance from the light source approaches the critical angle. The reflected light that is totally reflected in proportion to the distance is emitted at a small emission angle. For this reason, the product of the light quantity emitted and the solid angle can be emitted equally at any position on the emission surface of the light guide plate.

  Furthermore, the light guide plate according to claim 7 is configured such that the inclined surface has an arc on the inside or the outside centered on the center portion of the inclined surface, or an arc is formed on the inside and outside of the inclined surface partially. Features.

The light guide plate according to the seventh aspect has the same size because the inclined surface has an arc inside or outside centered on the central portion of the inclined surface, or partly inside and outside the inclined surface. In the case where the emission position in the light guide plate is an arc on the inside of the inclined surface, it can be brought closer to the light source side. Further, when the light source is near, the totally reflected light becomes parallel light, and when the light source is far, the totally reflected light can be condensed.
Further, when the emission position in the light guide plate having the same size is formed as an arc on the outer side of the inclined surface, it can be moved away from the light source side. Further, when the light source is near, the totally reflected light becomes parallel light, and when the light source is far, the totally reflected light can be diffused.
Further, different actions such as condensing and diffusing can be obtained on one inclined surface by forming a circular arc partially inside and outside on one inclined surface.

In addition, the flat illumination device according to claim 8 includes an L-shaped light source, an incident portion that guides light from the light source, a surface portion that emits the light, and a back surface portion that is located on the opposite side of the surface portion. It has a side part that connects these front part and back part, and two connecting side parts are incident parts, and it corresponds to the light flux from the light source continuously at the position corresponding to the luminance distribution or light energy distribution of the light source In the vicinity of one corner where the two side surfaces facing the L-shaped portion of the light source are connected to each other, the linear portion of the light source has a density distribution that increases in proportion to the distance from the light source. The two side parts facing the both ends of the light source are inclined closer to the side part than the two side parts facing the linear part of the light source so that they are farther from the side part and one corner than the two opposing side parts. Optical element provided with the surface facing the light source on the front or back The light guide plate in the light source, a correction sheet that corrects fine luminance spots of the light emitted from the light guide plate, and covers the light guide plate except for the incident portion and the light exit surface, and reflects the leaked light from the light guide plate again into the light guide plate And a reflector.

The planar illumination device according to claim 8 includes an L-shaped light source, an incident portion that guides light from the light source, a front surface portion that emits the light, a back surface portion that is located on the opposite side of the front surface portion, and these Inclination corresponding to the light flux from the light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source with the two side surfaces to be connected as the incident part. It has a density distribution that increases in function in proportion to the distance from the light source, and faces the linear portion of the light source in the vicinity of one corner where two side surfaces facing the L-shaped portion of the light source are connected. The two side surfaces facing the both ends of the light source are separated from the side surfaces and one corner rather than the two side surfaces, and the inclined surface is closer to the side surface than the two side surfaces facing the linear portion of the light source. An optical element facing the light source is provided on the front or back side. A light guide plate, a correction sheet that corrects fine luminance spots of light emitted from the light guide plate, and a reflector that covers the light guide plate other than the incident portion and the light exit surface and reflects light leaked from the light guide plate again into the light guide plate Therefore, total reflection and refraction are always performed by the inclined surface of the continuous optical element at a position where the luminance and energy from the light source are equal, and the luminance and energy equivalent to continuity are emitted to the emission surface side. Can do. In addition, the density distribution of the optical element increases functionally in proportion to the distance from the light source as the brightness and energy from the light source decay, and the amount of light emitted from any position of the light guide plate and its solid angle It is possible to emit the same product or to freely control the exit angle from the exit surface by setting the angle of the inclined surface.

The planar illumination device according to claim 9 is an L-shaped light source, an incident portion that guides light from the light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, It has side parts that connect these front and back parts, and the two side parts to be connected are incident parts, and it corresponds to the light flux from the light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source. In the vicinity of one corner where the two side surfaces facing the L-shaped portion of the light source are connected to each other, the linear portion of the light source has a density distribution that increases in proportion to the distance from the light source. The two side parts facing the both ends of the light source are inclined closer to the side part than the two side parts facing the linear part of the light source so that they are farther from the side part and one corner than the two opposing side parts. An optical element provided with the surface facing the light source is a front surface portion or a back surface portion. A light guide plate, a correction sheet that corrects minute luminance spots of light emitted from the light guide plate, and a reflection that covers the light guide plate other than the incident portion and the light exit surface and reflects light leaked from the light guide plate again into the light guide plate And a body.

The flat illumination device according to claim 9 includes an L-shaped light source, an incident portion that guides light from the light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, and these It has a side part that connects the front part and the back part, and the two side parts to be connected are incident parts, corresponding to the light flux from the light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source. It has an inclined surface, has a density distribution that increases functionally in proportion to the distance from the light source, and faces the linear portion of the light source in the vicinity of one corner where two side surfaces facing the L-shaped portion of the light source are connected. The two side surfaces facing the both end portions of the light source are inclined so that they are closer to the side surface portions than the two side surface portions facing the linear portion of the light source so that they are farther from the side surface portion and one corner than the two side surface portions. On the front or back of the optical element A light guide plate, a correction sheet that corrects minute luminance spots of light emitted from the light guide plate, and a reflector that covers the light guide plate other than the incident portion and the light exit surface and reflects light leaked from the light guide plate again into the light guide plate Therefore, total reflection and refraction are always performed by the inclined surface of the equivalent optical element continuously at the position where the luminance and energy from the light source are equal, and the same luminance and energy are continuously emitted to the emission surface side. can do. Moreover, the product of the amount of light emitted at every position of the light guide plate and its solid angle is equal so that the density distribution of the optical element increases in proportion to the distance from the light source as the luminance and energy from the light source decrease. The emission angle from the emission surface and the optical element itself can be continuously changed by setting the angle of the inclined surface.

As described above, the light guide plate according to claim 1 includes an incident portion that guides light from an L-shaped light source, a surface portion that emits the light, and a back surface portion that is located on the opposite side of the surface portion. In the light guide plate having the side surface portion connecting the front surface portion and the back surface portion and having the two connected side surface portions as the incident portions, the front surface portion or the back surface portion corresponds to the luminance distribution or light energy distribution of the light source. An optical element having an inclined surface corresponding to the light flux from the light source continuously at a position has a density distribution that increases functionally in proportion to the distance from the L-shaped light source and faces the L-shaped portion of the light source. In the vicinity of one corner where the two side portions are connected, the straight line of the light source is formed on the two side portions facing the both end portions of the light source so that the two side portions facing the straight portion of the light source are separated from the side surface portion and one corner. It ’s closer to the side than the two sides facing the part. Since the inclined surface faces the light source, total reflection or refraction is always performed by the continuous inclined surface of the optical element at a position where the luminance and energy from the light source are equal, and the luminance is equivalent to continuity on the exit surface side. And energy can be emitted. Moreover, the product of the amount of light emitted from any position of the light guide plate and its solid angle so that the optical element density distribution increases functionally in proportion to the distance from the light source as the luminance and energy from the light source decay. Can be emitted equally, so that emitted light with uniform brightness and viewing angle can be obtained.

The light guide plate according to claim 2 includes an incident portion that guides light from an L-shaped light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, and these surface portions. In the light guide plate having a side surface portion connecting the back surface portion and the two side surface portions to be connected as the incident portion, the front surface portion or the back surface portion is continuously located at a position corresponding to the luminance distribution or light energy distribution of the light source. In particular, the optical element having an inclined surface corresponding to the light flux from the light source has a density distribution that increases functionally in proportion to the distance from the L-shaped light source and is opposed to the L-shaped portion of the light source. In the vicinity of one corner to which the side surface is connected, the two side surfaces facing both ends of the light source are opposed to the linear portion of the light source so that they are farther from the side surface and one corner than the two side surfaces facing the linear portion of the light source. The inclined surface is closer to the side surface than the two side surfaces Is always directed to the light source , so that it is always subjected to total reflection and refraction by the inclined surface of the equivalent optical element continuously at the position where the luminance and energy from the light source are equal, and continuously with the same luminance and Energy can be emitted. Moreover, the product of the amount of light emitted from any position of the light guide plate and its solid angle so that the optical element density distribution increases functionally in proportion to the distance from the light source as the luminance and energy from the light source decay. Can be emitted equally, so that emitted light with uniform brightness and viewing angle can be obtained. In addition, the product of the amount of light emitted from the optical element and its solid angle is equal by controlling the length of the optical element and the distance between adjacent optical elements, but the optical element is lost. Thus, it is possible to obtain lower light energy than the place where the optical element is present, and to express a desired luminance distribution on the light guide plate.

  Furthermore, in the light guide plate according to claim 3, since the cross section of the optical element is triangular, trapezoidal, or arcuate and continuous or continuous, the light rays that have entered the light guide plate from the incident portion of the light guide plate are triangular. An inclined surface having a shape, a trapezoidal shape, and an arc shape can exist at a position corresponding to the light flux from the light source. And when these are continuous, the same brightness | luminance and energy can be radiate | emitted at any position, and even if it is continuous, the same brightness | luminance and energy can be radiate | emitted continuously at every position.

  In addition, the light guide plate according to claim 4 increases the height of the optical element as the optical element is moved away from the light source, and / or partially raises or lowers the height of the optical element. Can be reflected. For this reason, it is possible to obtain a large amount of emitted light even at a position far from the light source to obtain a uniform emission brightness from the light guide plate regardless of the distance of the light source, or to set the height of the light guide plate at any position. The amount of light emitted from can be increased or decreased, and the angle of light emitted from an arbitrary position of the light guide plate can be changed. As a result, it is possible to control the luminance and the viewing angle at any desired position of the light guide plate.

  Further, in the light guide plate according to claim 5, since the angle between the inclined surface and the front surface portion and the back surface portion is in the range of π / 2-2 · critical angle to critical angle, the maximum incidence of the light beam guided into the light guide plate Since the range from the angle to the minimum angle that breaks the critical angle is used, all the reflected light can break the critical angle. Thereby, since the emission angle range from the emission surface of the light guide plate can be made large, the required emission angle can be freely selected and can be adapted to the purpose.

  Further, in the light guide plate according to claim 6, since the angle formed between the front surface portion and the back surface portion in proportion to the distance from the light source approaches the critical angle, even with the attenuation of luminance and energy from the light source, The reflected light totally reflected in proportion to the distance from the light source is emitted at a small emission angle. For this reason, the product of the quantity of light emitted and the solid angle thereof can be emitted equally at any position on the emission surface of the light guide plate, and a uniform emission amount and a uniform viewing angle can be obtained.

  Further, in the light guide plate according to claim 7, since the inclined surface has an arc on the inner side or the outer side around the central portion of the inclined surface, or partially on the inner side and the outer side of the inclined surface, When the emission position in the light guide plate of the same size is formed as an arc inside the inclined surface, it can be brought closer to the light source side. Further, when the light source is near, the totally reflected light becomes parallel light, and when the light source is far, the totally reflected light can be condensed. Furthermore, when the exit position in the light guide plate of the same size is formed as an arc outside the inclined surface, it can be moved away from the light source side. In addition, when the light source is close, the totally reflected light becomes parallel light, and when the light source is far, the totally reflected light can be diffused. By two different arcs, it is possible to obtain actions and effects such as condensing and diffusing on one inclined surface. Thereby, the size of the light guide plate, the necessary amount of emitted light, the viewing angle, and the like can be freely controlled.

In addition, the flat illumination device according to claim 8 includes an L-shaped light source, an incident portion that guides light from the light source, a surface portion that emits the light, and a back surface portion that is located on the opposite side of the surface portion. It has a side part that connects these front part and back part, and two connecting side parts are incident parts, and it corresponds to the light flux from the light source continuously at the position corresponding to the luminance distribution or light energy distribution of the light source In the vicinity of one corner where the two side surfaces facing the L-shaped portion of the light source are connected to each other, the linear portion of the light source has a density distribution that increases in proportion to the distance from the light source. The two side parts facing the both ends of the light source are inclined closer to the side part than the two side parts facing the linear part of the light source so that they are farther from the side part and one corner than the two opposing side parts. Optical element provided with the surface facing the light source on the front or back The light guide plate in the light source, a correction sheet that corrects fine luminance spots of the light emitted from the light guide plate, and covers the light guide plate except for the incident portion and the light exit surface, and reflects the leaked light from the light guide plate into the light guide plate again. A reflector, so that total reflection or refraction is always performed by the inclined surface of the optical element equivalent to continuity at a position where the luminance and energy from the light source are equal, and brightness and energy equivalent to continuity are provided on the exit surface side. Can be emitted. In addition, the density distribution of the optical element increases functionally in proportion to the distance from the light source as the brightness and energy from the light source decay, and the amount of light emitted from any position of the light guide plate and its solid angle It is possible to emit the same product or to freely control the exit angle from the exit surface by setting the angle of the inclined surface. As a result, according to the required purpose of the flat illumination device, it is possible to realize a design with a high degree of freedom and a flat illumination device such as emphasizing luminance, viewing angle, or uniformity.

The planar illumination device according to claim 9 is an L-shaped light source, an incident portion that guides light from the light source, a surface portion that emits the light, a back surface portion that is located on the opposite side of the surface portion, It has side parts that connect these front and back parts, and the two side parts to be connected are incident parts, and it corresponds to the light flux from the light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source. In the vicinity of one corner where the two side surfaces facing the L-shaped portion of the light source are connected to each other, the linear portion of the light source has a density distribution that increases in proportion to the distance from the light source. The two side parts facing the both ends of the light source are inclined closer to the side part than the two side parts facing the linear part of the light source so that they are farther from the side part and one corner than the two opposing side parts. An optical element provided with the surface facing the light source is a front surface portion or a back surface portion. A light guide plate, a correction sheet that corrects minute luminance spots of light emitted from the light guide plate, and a reflection that covers the light guide plate other than the incident portion and the light exit surface and reflects light leaked from the light guide plate again into the light guide plate Therefore, total reflection and refraction are always performed by the inclined surface of the equivalent optical element continuously at the position where the luminance and energy from the light source are equal, and the same luminance and energy are continuously given to the exit surface side. Can be emitted. In addition, the density distribution of the optical element increases functionally in proportion to the distance from the light source as the brightness and energy from the light source decay, and the amount of light emitted from any position of the light guide plate and its solid angle It is possible to emit the same product or to control the emission angle from the emission surface and the continuous change of the optical element itself by setting the angle of the inclined surface. As a result, according to the required purpose of the flat illumination device, it is possible to realize a design with a high degree of freedom and a flat illumination device such as emphasizing luminance, viewing angle, or uniformity.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In the present invention, an optical element having an inclined surface corresponding to a light flux from a light source is continuously or continuously provided at a position corresponding to the luminance distribution or light energy distribution of the light source at a distance from the light source on the front surface portion or the back surface portion. The present invention provides a flat illumination device including a light guide plate having a density distribution that increases in proportion to a function and a light source having directivity and directivity distribution.

1 and 2 are schematic views of a light guide plate according to the present invention, and FIG. 3 is a schematic locus diagram of light rays of the light guide plate according to the present invention.
The flat illumination device is generally configured by the light guide plate 2, the light source 3b, a reflector (not shown), a correction film, and a reflection case shown in FIGS.

  The light guide plate 2 is formed of a transparent acrylic resin (PMMA) or polycarbonate (PC) having a refractive index of about 1.4 to 1.7. The light guide plate 2 includes a side surface portion 11, a front surface portion 8 for light emission, and a back surface portion 9 located on the opposite side and an incident portion 7 that guides light from the light source 3b.

As shown in FIG. 1, the light guide plate 2 can be configured such that the optical element 20 is continuously applied to the front surface portion 8 or the back surface portion 9 at a position corresponding to the luminance distribution or light energy distribution of the light source 3b.
Further, as shown in FIG. 2, the light guide plate 2 may be configured to continuously apply the optical element 20 ′ to the front surface portion 8 or the back surface portion 9 at a position corresponding to the luminance distribution or light energy distribution of the light source 3b. it can.

Here, the length of the optical element 20 ′ is shortened to reduce the total reflection amount on the inclined surface, or the length is increased to increase the total reflection amount on the inclined surface. Thereby, the total amount of reflection from the optical element 20 ′ can be controlled.
Further, the control is performed by increasing the interval between adjacent optical elements 20 'or decreasing the interval. As a result, the product of the amount of light emitted from the optical element 20 ′ and the solid angle thereof is equal, but the optical energy lower than the place where the optical element 20 ′ is present at the position where the optical element 20 ′ is missing (interval). Get. Thereby, a desired luminance distribution can be expressed in the light guide plate 2.

  Furthermore, as the light guide plate 2 moves away from the light source 3b, the luminance and energy from the light source 3b attenuate. For this reason, the optical element 20 is increased as the distance from the incident portion 7 increases. Then, the optical element 20 applied to the front surface portion 8 or the back surface portion 9 has a density distribution that increases exponentially in proportion to the distance from the light source 3b. Thereby, the product of the unit area of the optical element 20 in the vicinity of the incident part 7 and the strong light intensity is equal to the product of the unit area of the optical element 20 far from the incident part 7 and the weak light intensity.

  In addition, the light guide plate 2 has an optical element 20 having a triangular shape, a trapezoidal shape, and an arc shape so that the optical element 20 has an inclined surface corresponding to the light bundle from the light source 3b, and efficiently inclines the light from the light source 3b without loss. Make a total reflection on the surface.

  Further, although not shown, the light guide plate 2 increases the height of the optical element 20 as the optical element 20 is moved away from the light source 3b. Thereby, the height of an inclined surface part can be made high, and the area of an inclined surface part can be enlarged. As a result, the optical element 20 far from the light source 3b can receive a large amount of light from the light source 3b. The received light is totally reflected by the inclined surface and deflected in the direction of the exit surface, so that a large amount of the exit light can be emitted even at a position far from the light source 3b. The emission brightness from the optical plate 2 can be obtained.

  Although not shown, the light guide plate 2 can raise or lower the height of the inclined surface portion by partially raising or lowering the optical element 20. Thereby, the area of an inclined surface part can be enlarged or reduced. As a result, the amount of light emitted from an arbitrary position of the light guide plate 2 can be increased or decreased, and the angle of emission from an arbitrary position of the light guide plate can be changed. As a result, it is possible to control the luminance at a desired position of the light guide plate 2 and the viewing angle.

  It should be noted that by partially changing the height of the optical element 20, for example, when the cross-sectional area is a triangular optical element 20, the height of one continuous triangular ridge can be continuously changed. The change of the emitted light can be made continuous.

In addition, the angle between the inclined surface of the optical element 20 and the front surface portion 8 and the back surface portion 9 is in the range of π / 2-2 · critical angle γ to critical angle γ. That is, the angle formed between the front surface portion 8 and the back surface portion 9 is made closer to the critical angle γ as the inclined surface is separated from the light source 3b in proportion to the distance from the light source 3.
Here, when the light from the light source 3b is guided to the inside of the light guide plate 2 from the incident portion 7, for example, when the material of the light guide plate 2 is a polycarbonate (PC) resin, the refractive index n of the polycarbonate resin is 1.59. Therefore, the light ray L0 that enters the light guide plate 2 from the air layer and exists in the light guide plate 2 is expressed by the equation 0 ≦ | α | ≦ sin ⁻¹ (1 / n) (where n is an air layer) And refractive index n = 1) substantially in the range of refraction angle α = ± 38.997 °.

  Further, the light incident on the light guide plate 2 within the range of the refraction angle α = ± 38.997 ° is sin γ = (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 polycarbonate resin which is a resin material used for the general light guide plate 2 is about n = 1.59, the critical angle γ is about γ = 38.97 °. In the case of a light guide plate using an acrylic resin (PMMA) material, the refractive index n of the acrylic resin is about n = 1.49, and the refraction angle α is about α = ± 42.38 °. The critical angle γ is also about γ = 42.38 °.

  For example, the refractive index n of the light guide plate 2 made of acrylic resin is about n = 1.49, and in the example of FIG. 3, the refraction angle α of the light beam entering the light guide plate 2 is about α = 42.38 °. Accordingly, the optical element 20 provided on the back surface portion 9 of the light guide plate 2 has an angle θ formed with the back surface portion 9 (from π / 2-2 · 42.38 °) in the range of 5.24 ° to 42.38 °. Among them, an inclined surface 21 having an angle θ1 = 5.24 ° which is a minimum value is provided in the vicinity of the incident portion 7, and an inclined surface 22 having an angle θ2 = 42.38 ° which is a maximum value is provided at a position away from the incident portion 7. Is provided.

  Among the light beams guided into the light guide plate 2 having the above-described configuration, a light beam L1 having an incident angle β of approximately 42 ° that is close to the incident portion 7 is on the inclined surface 21 of the optical element 20 (inclination θ1 = 5.24 °). Total reflection. The totally reflected light beam L11 travels in the direction of the surface portion 8 of the light guide plate 2. Here, the light beam L11 breaks the critical angle γ (outgoing angle of about 61 °) and exits from the surface portion 8 (outgoing angle of about 61 °). The light is emitted as L12.

  As described above, the light beam having a small refraction angle among the light beams that have entered the light guide plate 2 is a light beam having a large incident angle other than the light beam that travels in the extending direction of the light guide plate 2 (the direction opposite to the light incident portion 7). There are many in the vicinity of. Therefore, the inclined surface 21 of the optical element 20 provided in the vicinity of the incident portion is inclined even by a light beam having a large incident angle so that the angle formed with the rear surface portion 9 is reduced by 90.degree. The light is totally reflected at the surface 21, proceeds in the direction of the surface portion 8, breaks the critical angle γ of the light guide plate 2, and can be emitted from the surface portion 8.

  In addition, among the light beams guided into the light guide plate 2, the light beam L2 having a light incident angle β = 2 ° that travels in a direction away from the incident portion 7 is the inclined surface 22 of the optical element 20 (inclination θ1 = 42.38). Total reflection at °). The totally reflected light beam L21 travels in the direction of the surface portion 8 of the light guide plate 2, where the light beam L21 breaks the critical angle γ (outgoing angle 2.24 °) outside the surface portion 8 (about 1.5 °). About) The light is emitted as outgoing light L22.

  In this way, light rays having a small refraction angle among light rays that have entered the light guide plate 2 travel in the opposite direction (extension direction) to the incident portion of the light guide plate 2 and collide with the optical element 20 provided near the incident portion 7. There is little probability to do. For this reason, the inclined surface 22 of the optical element 20 provided at a position away from the incident portion 7 is set so that the angle formed with the rear surface portion 9 is equal to the critical angle γ, and even the light having a small incident angle is totally reflected by the inclined surface 22. Then, it can proceed in the direction of the surface portion 8, break the critical angle γ of the light guide plate 2, and emit from the surface portion 8.

Therefore, as can be seen from the explanation of the two extreme cases as described above, in the light guide plate of this example, the inclination angle of the inclined surface of the optical element 20 increases with increasing distance from the incident portion 7 with respect to the light beam from the incident portion 7. The angle formed with the back surface portion 9 is made closer to the critical angle γ in proportion to the distance from the light source 3b so that the inclined surface 21 gradually becomes the inclined surface 22. As a result, the product of the amount of light emitted at any position on the exit surface of the light guide plate 2 by the optical element 20 corresponding to the distance from the light source 3b and the solid angle thereof is equal even with the attenuation of luminance and energy from the light source 3b. Can be emitted.
Although the concave optical element 20 has been described here as an example, in the case of a convex shape, the inclined surface 21 located on the opposite side of the inclined surface 21 or the inclined surface 22 faces the light source side. The same operations and effects as described above can be obtained.

  Here, the optical element 20 having the inclined surface provided on the back surface portion 9 has been described. However, as described above, the light incident from the incident portion is, for example, acrylic resin, the refraction angle α is α = ± 42. In the case of polycarbonate resin, the angle of refraction α is α = ± 38.997 °, which proceeds in the direction of the front surface portion 8 and the rear surface portion 9, so that the optical element 20 is provided on the front surface portion 8 and is the same as described above. When configured, the light guide plate 2 used for the front light can be obtained. Further, the emitted light can be freely controlled by selecting the angle of the inclined surface of the optical element 20 so that the light beam once totally reflected by the front surface portion is again totally reflected by the back surface portion 9 again.

  Further, by forming an arc inward or outward with the central portion of the inclined surface 21 or the inclined surface 22 of the optical element 20 as the center, the emission position within the light guide plate 2 of the same size is set to the inclined surface 21 or the inclined surface 22. When the inner side of the surface is an arc, it can be brought closer to the light source side, and when the outer side of the inclined surface 21 or the inclined surface 22 is an arc, it can be moved away from the light source side.

Further, when the outside of the inclined surface 21 or the inclined surface 22 is an arc, the totally reflected light becomes parallel light when the light source 3b is near, and the totally reflected light can be diffused when the light source 3b is far. .
Furthermore, when the inside of the inclined surface 21 or the inclined surface 22 is an arc, the totally reflected light becomes parallel light when the light source 3b is near, and the totally reflected light is condensed when the light source 3b is far. it can.

  Also, two inclined arcs 21 and 22 on the optical element 20 are provided on one inclined surface, for example, close to the surface portion 8 and the back surface portion 9 of the inclined surface 21 or the inclined surface 22. By forming an arc in the inner direction at the location and an arc in the outer direction at a location far from the front surface portion 8 and the back surface portion 9, it is possible to obtain two different light collection and diffusion effects on one inclined surface. it can.

  As shown in FIG. 1, when the light source 3b is a line such as a CCFL (cold tube), the optical element 20 has a luminance distribution because the luminance near the electrode of the CCFL (cold tube) is lower than the others. Is uniform except for both ends, and both ends are attenuated, so the distribution corresponds to this. In other words, the optical elements 20 at both ends are extremely close to the incident part 7 and are arranged so that the pitch of the optical elements 20 becomes finer as the position (distant) faces the incident part 7.

As shown in FIG. 1, the optical element 20 described in detail here has a luminance near the electrode of the CCFL (cold tube) when the light source 3b has an L (L) shape such as CCFL (cold tube). Is attenuated lower than the others, and the luminance distribution is the highest in the vicinity of the end 60 where the two side surfaces 11 of the light guide plate 2 intersect, and the luminance near the diagonal connecting the diagonal 6a with the end 60 is higher than the luminance near both sides. Since the distribution is high, the distribution corresponds to this. That is, the optical elements 20 near both ends of the light source 3b are extremely close to the incident portion 7, and the pitch of the optical elements 20 near the diagonal connecting the diagonal 6a from the vicinity of the end 60 where the two side surfaces 11 of the light guide plate 2 intersect is rough. In the vicinity of the end 6 facing the incident part, the distribution is particularly dense.
Note that FIG. 2 shows a continuous distribution of optical elements 20 ′ in which the continuous optical elements 20 of FIG. 1 are discontinuously separated.

  Although not shown here, even in the case where the light source 3b is a U (U) shape such as a CCFL (cold tube), the luminance of the vicinity of the light source 3b is similarly low, and the side surface portion 11 of the light guide plate 2 without the light source 3b is used. Since only one has the lowest luminance, the optical element 20 becomes denser as it approaches the middle of the opposite electrode from the vicinity of the electrode of the light source 3b as a distribution corresponding to these, and at the bottom of the U-shaped U shape. The optical elements 20 are densely provided at opposing positions.

  It should be noted that the optical element 20 ′ is continuously increased in function in proportion to the distance from the light source 3b on the front surface portion 8 or the back surface portion 9 shown in FIG. 2 at a position corresponding to the luminance distribution or light energy distribution of the light source 3b. The length of the optical element 20 that is continuously provided is controlled by the total reflection amount on the front surface portion 8 and the back surface portion 9 by increasing / decreasing or increasing / decreasing the light amount of the light source 3b. The amount of light emitted from can be controlled.

The optical element 20 has a triangular, trapezoidal, or arcuate cross section, and has a continuous concave shape or convex shape that ends at the end of the light guide plate 2 having a base width of, for example, about 5 μm to 100 μm. Can be configured.
Similarly, the optical element 20 has a triangular shape, a trapezoidal shape, and an arc-shaped cross section, for example, has a concave shape or a convex shape with a base width of about 5 μm to 100 μm, and the surface portion 8 of the light guide plate 2 or the like. It can be set as the structure continuously provided in the position corresponding to the brightness | luminance and light energy distribution of the light source 3b on the back surface part 9. FIG.

In this way, by providing the continuous or continuous optical elements 20 and 20 ′ on the front surface portion 8 and the back surface portion 9 of the light guide plate 2, the inclined surfaces of the optical elements 20 and 20 ′ bring the light source 3 b into the light guide plate 2. The incoming light beam is totally reflected, and directivity and energy with the same light quantity can be emitted continuously or continuously at any position.
Further, the adjacent interval between the continuous optical elements 20 ′ shown in FIG.

  A reflector (not shown) is made of a sheet of metal such as a white insulating material or a metal vapor-deposited such as aluminum, or the like, surrounds the incident portion 7 of the light guide plate 2 and the light source 3b, and reflects light from the light source 3b. Then, the reflected light is incident again on the incident portion 7 of the light guide plate 2.

A correction sheet (not shown) is made of a permeable resin or the like, and has an uneven surface for deflecting light on the surface. This correction sheet corrects the emitted light from the light guide plate 2, so that the emitted light with high luminance is diffused, the emitted light with low luminance is condensed, or the whole is diffused or partially diffused. Select the diffusion sheet, condensing sheet, scattering sheet, diffusing condensing sheet, etc. to be condensed or corrected according to the purpose, and use the forward direction or reverse direction with the processed surface facing upward Use in the same way.
Note that this correction sheet may not be used when outgoing light having directivity is required depending on the distribution and shape of the optical element 20.

  The reflector (not shown) is made of a sheet in which a white material such as titanium oxide is mixed in a thermoplastic resin or a metal sheet such as aluminum on a sheet of a thermoplastic resin, a metal foil laminated, or a sheet-like metal. Become. The reflector covers portions other than the incident portion 7 and the incident portion and the surface portion 8, and reflects or irregularly reflects light other than light emitted from the light source 3 b to the surface portion 8 by the light guide plate 2. Incident light is emitted so that all light from the light source 3 b is emitted from the surface portion 8.

Schematic of light guide plate according to the present invention Schematic of light guide plate according to the present invention Schematic locus diagram of light rays of a light guide plate according to the present invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Light guide plate, 3b ... Light source, 7 ... Incident part, 6, 6a ... End part, 8 ... Surface part, 9 ... Back surface part, 10 ... Reflection end surface part, 11 ... Side part, 20, 20 '... Optical element, 21, 22 ... inclined surface, β ... incident angle, α ... refraction angle, γ ... critical angle, n ... refractive index, θ ... angle formed by the front and back surfaces and the inclined surface, L1, L11, L12, L2, L21, L22 ... Light rays.

Claims (9)

An incident part that guides light from an L-shaped light source, a surface part that emits the light, a back part that is located on the opposite side of the surface part, and a side part that connects the surface part and the back part In the light guide plate having the two side surfaces to be connected as the incident portion, the front surface portion or the back surface portion is continuously exposed from the light source at a position corresponding to the luminance distribution or light energy distribution of the light source. the two facing L-shaped portions of the light source and having a distance function to the density distribution increases in proportion from the previous SL L-shaped light source of the optical element having an inclined surface corresponding to the light beam of the In the vicinity of one corner to which the side surface portion is connected, the two side surface portions facing the both end portions of the light source are separated from the side surface portion and the one corner rather than the two side surface portions facing the linear portion of the light source. 2 facing the straight portion of the light source The light guide plate, characterized in that said inclined surface such as by the side surface portion from the side surface portion is provided facing the light source. An incident part that guides light from an L-shaped light source, a surface part that emits the light, a back part that is located on the opposite side of the surface part, and a side part that connects the surface part and the back part In the light guide plate in which the two side surface portions to be connected are the incident portion, the light source is continuously provided at a position corresponding to a luminance distribution or light energy distribution of the light source on the front surface portion or the back surface portion. two opposed to the L-shaped portion of the light source and having a distance proportional functionally density distribution that increases in the optical element before Symbol L-shaped light source having an inclined surface corresponding to the light beam from the In the vicinity of one corner to which the side surface portion is connected, the two side surface portions facing the both end portions of the light source so as to be farther from the side surface portion and the one corner than the two side surface portions facing the linear portion of the light source. Then, facing the straight part of the light source One of the light guide plate, characterized in that said inclined surface such as by the side surface portion from the side surface portion is provided facing the light source. The light guide plate according to claim 1, wherein the optical element has a triangular shape, a trapezoidal shape, or an arc shape in cross section and is continuous or continuous. 3. The light guide plate according to claim 1, wherein the optical element is configured such that the height of the optical element increases or / and partially increases or decreases as the distance from the light source increases. 4. The light guide plate according to claim 1, wherein the inclined surface has an angle formed between the front surface portion and the back surface portion in a range of π / 2-2 · critical angle to critical angle. The light guide plate according to claim 1, wherein an angle formed between the inclined surface and the front surface portion and the back surface portion approaches a critical angle in proportion to a distance from the light source. The inclined surface has an arc inside or outside centered on a central portion of the inclined surface, or a circular arc partially inside and outside the inclined surface. 2. The light guide plate according to 2. An L-shaped light source, an incident portion for guiding light from the light source, a surface portion for emitting the light, a back surface portion located on the opposite side of the surface portion, and the surface portion and the back surface portion. And two inclined side surfaces corresponding to the light flux from the light source at positions corresponding to the luminance distribution or light energy distribution of the light source. And has a density distribution that increases functionally in proportion to the distance from the light source and faces the linear portion of the light source in the vicinity of one corner where the two side portions facing the L-shaped portion of the light source are connected. The two side surfaces opposed to both end portions of the light source are separated from the two side surface portions opposed to the linear portion of the light source so as to be farther from the side surface portion and the one corner than the two side surface portions. The inclined surface so that it approaches the side A light guide plate having an optical element provided facing the serial light source on the surface portion or the back portion, and a correction sheet for correcting the fine luminance unevenness of the light emitted from the light guide plate, wherein the incident portion and the exit surface of the light guide plate And a reflector that reflects light leaked from the light guide plate again into the light guide plate. An L-shaped light source, an incident portion for guiding light from the light source, a surface portion for emitting the light, a back surface portion located on the opposite side of the surface portion, and the surface portion and the back surface portion. An inclined surface corresponding to the light flux from the light source continuously at a position corresponding to the luminance distribution or light energy distribution of the light source. And having a density distribution that increases functionally in proportion to the distance from the light source, and in the vicinity of one corner where the two side surface portions opposed to the L-shaped portion of the light source are connected to the linear portion of the light source. The two side surfaces facing the both end portions of the light source are more apart from the two side surface portions facing the linear portion of the light source so that they are farther from the side surface portion and the one corner than the two opposed side surface portions. The inclined surface so as to approach the side surface portion A correction sheet for correcting a light guide plate having an optical element provided facing the light source into a surface portion or rear portion, a fine luminance unevenness of the light emitted from the light guide plate, wherein the incident portion and the exit surface of the light guide plate And a reflector that reflects light leaked from the light guide plate again into the light guide plate.

Images