JP2010186653A - Lighting device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device and a display device which control an emission angle to achieve a highly efficient color mixture to solve the problem that emission angle control is difficult in color mixture due to scattering, resulting in inefficient color mixture accompanying absorption. <P>SOLUTION: On the upper side of a horizontal plane on the bottom of a light guide plate, strip-shaped convex reflective surfaces are symmetrically combined with respect to a ridge and are arranged at a pixel pitch X to form convex reflective surfaces 5A and 5B. On the lower side of the horizontal plane on the bottom of the light guide plate, strip-shaped convex reflective surfaces are arranged at the pixel pitch X to form a triangular-wave reflection lattice. Parallel light sources of two colors are set symmetrically on the upper side of the horizontal plane at an elevation angle equal to a tangent to the apex of the strip-shaped convex reflective surfaces forming the ridge, and a parallel light source of a third color is disposed on the lower side of the horizontal plane. The convex reflective surfaces 5A and 5B facing the light sources in two directions are exposed to incoming parallel light from both light sources to project expanded light flux onto subpixels 27A and 27B. Parallel light from the light source on the lower side of the horizontal plane is reflected on a convex reflective surface 5C, which causes the reflected light to pass through the pitch between the convex reflective surfaces 5A and 5B to fall onto a third subpixel 27C. Hence, three colors are mixed at the same pixel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an illuminating device and a display device in which light emission from a plurality of light-emitting elements is controlled by a reflecting element or a refracting element configured in a lattice shape to improve color mixing characteristics.

Semiconductor light emitting devices are widely used in various display devices and traffic signals because of their excellent features such as small size, high efficiency, long life, low voltage operation, and high speed response.
White light resulting from additive color mixing of red, green, and blue primary light emitting elements has discontinuous spectral characteristics due to the narrow emission spectrum width of a single substance, but the liquid crystal display device has three colors of red, green, and blue light emitting elements. Even in the discontinuous spectrum due to the three primary color white light using the three color light emitting elements can be used to display the intermediate color by the control signal of the three colors. In the proposal (FIG. 27, Patent Document 1) in which light emitting elements of three colors are provided on the inner surface of the cone to increase the distance for color mixing by backscattering, absorption increases with multiple reflection and efficiency decreases. There is a proposal to reduce the difference in distance and angle between each light emitting element and the reflecting mirror by placing three color light emitting elements in the same package and steepening the inclination of the reflecting mirror near the light emitting element (FIG. 28, Patent Document). 2) Uniform color mixing can be obtained only under local conditions. The following fluorescent white light-emitting diodes are often used because it is difficult to sufficiently mix the three-color light-emitting elements in the same package and the power supply voltages of the elements are different.

The blue phosphor of the blue light emitting diode is irradiated on the yellow phosphor, and the spectrum of the fluorescent white light emitting diode by complementary color consists of two peaks in a sharp yellow color and a gentle yellow region (Patent Document 3). It has a strong bluish spectral characteristic with very little red color and a large dip in green. However, fluorescent white light-emitting diodes are used as backlights for liquid crystal display devices such as mobile phones because they are easier than the mixing of the three primary colors.

With the improvement of the luminous efficiency of semiconductor light emitting devices, the application to lighting with light emitting diodes that can be reduced in size compared to fluorescent lamps has been promoted, projectors with a narrow emission angle by taking advantage of the features of semiconductor light emitting devices close to point light sources, etc. Has begun to be used. Since the allowable temperature rise of the light emitting diode is smaller than that of other light sources, it is expensive to obtain a large luminous flux because a large number of chips are required. In order to spread, it is necessary to reduce the price, and the spectrum is strongly bluish with emphasis on efficiency.
When the fluorescent light near yellowish green with the highest relative visibility is excited with a blue light-emitting diode and fluorescent white light by complementary color is used for general illumination, the irradiated object in the red or dip wavelength range becomes white light in the continuous spectrum. It becomes darker than that. There are proposals for mixing red phosphors and the like, and for replacing yttrium with gadolinium and shifting to the longer wavelength side to improve efficiency while improving color rendering (Patent Document 3).

  When a white light backlight source is separated into three colors by a color filter, 2/3 of the light is absorbed by the color filter and the efficiency is reduced. Therefore, additive color mixing is performed using three primary color light emitting elements without using a color filter. As a method for this, there is a proposal in which a 45 ° groove is provided in the light guide plate in the number of pixels and three layers of the light guide plate that totally reflects in the direction of the liquid crystal panel at the groove interface are stacked (FIG. 29, Patent Document 4). There is a method in which a light shielding layer is provided at the interface of a plurality of rod-shaped light guides, light of each color of light emitting diodes is shielded and propagated through the rod-shaped light guide, and three-color light is supplied to the liquid crystal stripe without using a color filter. It has been proposed (FIG. 30, Patent Document 5). There has been proposed a liquid crystal display device in which light sources of three colors are installed on three sides of a liquid crystal panel, square pyramids are provided in a matrix on a light guide plate, and predetermined pixels of the liquid crystal panel are irradiated by inclined surfaces of the quadrangular pyramids (see FIG. 31, Patent Document 6). There is a proposal to propagate parallel light of the three primary colors to a light guide plate having a convex reflection surface arranged in a terraced shape, expand the light beam in the pixel direction and reflect it, and distribute the reflected light of each color into stripes by the reflective / transmissive elements ( FIG. 32, Patent Document 7).

A three-wavelength cold cathode tube close to a line light source is often used as an imaging light source. However, since the fluorescent material of each color has a line spectrum, the wavelength characteristics are uneven and accurate color reproduction cannot be achieved. Since the half-value width at which the luminous intensity of the light-emitting diode is about half the peak is 20 nm to 60 nm, there is a proposal to cover the visible light region using 6 to 9 colors (Patent Document 7). Seven types of light-emitting elements are arranged near the center of the substrate, enclosed in a lens shallower than the focal plane, and mixed with the scattering material layer on the focal plane to form white light by connecting at half-value wavelengths of each color. An application as a scanner light source after conversion by a conversion element is shown.

JP 2005-353506 A JP 2004-87935 A Japanese Patent No. 3246386 JP-A-6-59252 Japanese Patent Laid-Open No. 2-111922 JP 2006-323221 A Patent 4114173

The proposal for mixing three colors of light emitting elements in the same package and mixing colors by a structure such as steep inclination of the reflecting mirror in the vicinity of the light emitting elements is different in distance and angle from each light emitting element to the reflecting mirror. Cause color spots. Since it is difficult to mix colors by regular reflection, the reflected light returns to the light source side and is absorbed during multiple reflections due to color mixing, such as using a scattering layer to backscatter on the inner surface of the cone to increase the scattering distance. To do.

  A white light emitting diode with a complementary color obtained by irradiating a yellow phosphor with blue light from a blue light emitting diode has a sharp blue light and a gentle yellow light spectrum, and lacks a red region and a blue green region. As the blending ratio of the phosphor increases, the peak of blue light decreases and the peak of fluorescence increases.However, when the fluorescence passes through the phosphor in the direction of travel, it exhibits yellow light and hits another yellow phosphor. The phosphor is colored and opaque and is absorbed because the fluorescence conversion rate is low with respect to the fluorescence wavelength. When the phosphor blending ratio is increased by supplementing the absorption, the efficiency further decreases. Therefore, the fluorescent white light emitting diode is given priority to efficiency, and becomes blue light with a large blue light spectrum.

When mixing phosphors over a wide wavelength band in order to improve color rendering, it is necessary to mix with a phosphor blending ratio corresponding to the conversion efficiency and specific luminous efficiency. The amount of long-wavelength phosphors increases in red with low specific visibility and conversion efficiency, and the light emitted from the long-wavelength phosphors is absorbed only by the short-wavelength phosphors and is not converted to fluorescence. . The probability that the yellow fluorescent light hits the yellow fluorescent material and the probability that the red fluorescent light hits the red fluorescent material also increase, and the efficiency decreases. For this reason, there is a problem that the efficiency is lowered when a plurality of kinds of phosphors are mixed and dispersed to realize white light having a continuous spectrum.

  As a method of additive color mixing using light emitting elements of three primary colors without using a color filter, a 45 ° groove is provided in the light guide plate in the number of pixels, and three light guide plates that totally reflect in the liquid crystal panel direction at the groove interface are stacked. The proposal requires a thickness of 1/3 of the screen width to provide a 45 ° inclination and the number of sub-pixels. When the screen width is 300 mm, the thickness of 100 mm per light guide plate is required, and the number of man-hours for processing grooves with the number of stripes Becomes more expensive.

The proposal of providing a light-shielding layer at the interface of a plurality of bar-shaped light guides, blocking the color-specific light, propagating through the bar-shaped light guide, and supplying three-color light to the liquid crystal stripe without using a color filter was light-shielded It is difficult to bundle and manufacture a filamentous light guide member having a sub-pixel width. When a light-transmitting sheet provided with a light shielding layer is laminated, tolerances of the sheet thickness are integrated and do not match the pixel dimensions of the liquid crystal. Since diffused light propagates through the light-transmitting material partitioned by the respective light shielding layers, in the case of a metal light shielding film, it is absorbed every time it is reflected and becomes darker in the distance.

In the proposal of providing a large number of reflectors with a quadrangular pyramid on the light guide plate and reflecting the three primary colors from three directions to the pixels and mixing the colors, only the inverse V-shaped reflected light is obtained by blocking the front quadrangular pyramid. When the pyramid is irradiated with oblique parallel light, it also hits the side surface, so that it becomes scattered light and enters other pixels and becomes unclear.

  The proposal for distributing the stripes by the light guide plate having a convex reflection surface arranged in a terraced shape and the reflection / transmission elements requires two types of light guide elements having different structures, and therefore requires accurate alignment.

Light-emitting diodes for traffic lights have a large directivity of the lens, so they consume a lot of current, such as being radiated unnecessarily into the sky. Since there is a pseudo-lighting phenomenon in which two lights that are not lit are brightened by receiving sunlight, a light-shielding plate that shields sunlight is provided.

The long axis direction of the strip-shaped reflecting surface is arranged on the horizontal plane so as to be orthogonal to the traveling direction of the parallel light from the light source, and the short axis direction of the strip-shaped reflecting surface is alternately inclined by ± 30 ° to form a triangular wave shape. Are arranged, the triangular wave reflection grating 4 is formed. FIG. 1 shows a structure in which a parallel light source is provided at a symmetrical position in the direction of 30 ° obliquely upward in the minor axis direction of the triangular wave reflection grating and the strip-like reflection surface.
Since the reflecting surfaces forming the pair of each parallel light source and the triangular wave lattice are parallel, they cannot enter the reflecting surface arranged on the side of the parallel light source forming the pair, and the parallel light source 30 ° above the horizontal plane. Parallel light from both sides is incident along the light source direction reflecting surface of the triangular wave reflector. When the light is incident on the reflecting surface along the parallel light of the opposing light source, the light incident from both is reflected vertically upward.
Assuming that the inclination of the triangular wave grating and the inclination angle of the inclined light is α, and the angle between the normal of the inclined surface and the vertical direction is β, the inclination α is 30 ° as shown in Equation 1.

As shown in the plan view of FIG. 2, the reflected lights from the left and right parallel light sources are all reflected in a comb shape according to the reflection surface on the light source side, and the parallel lights from the left and right are alternately arranged in a comb shape. If the lattice pitch is a stripe having a size that cannot be recognized by the naked eye, and the left and right parallel light sources are two different colors, the additive color mixing is performed.

When colors are mixed with a scattering surface or a diffuser with dispersed diffusing materials, they are scattered at a very wide radiation angle with no directivity. However, when reflected light is alternately arranged in a comb shape by a reflection grating, additive colors are emitted as parallel light. Subsequent processing becomes easy.
Parallel light can be obtained by installing the light emitting element 1 at the focal point of the parabolic mirror 6, but since the chip size of the light emitting diode is about 250 μm on each side, the center depends on the size of the light emitting element provided at the focal point of the parabolic mirror. An optical path difference occurs in the light emitted from the peripheral part and the peripheral part, and there is an error from the parallel light shown in FIG. The error angle θ from the parallel light emitted from the outer peripheral portion is expressed by the following equation (2) based on the length r from the center of the light emitting element to the outer peripheral portion, the coordinates m (x, y) of the parabolic mirror, and the focal length p. In order to reduce the error angle θ, it is necessary to increase the focal length.

FIG. 4 shows the reflection position y dependency of a parabolic mirror with p = 2.5 mm.

In order to change the emitted light to diffuse light or convergent light instead of parallel light, the emission angle can be controlled by using a lens, a reflecting mirror, etc. Can be controlled. FIG. 5 shows a side view of a state in which the reflection grating is formed by the convex reflection surface 5 to expand the light flux. If the radiation angle directions of the curved surfaces forming a pair are not equal, depending on the viewing direction, only one of the components will be formed, resulting in color spots. In FIG. 5, the reflected light of the left light source light at the trough of the grating and the reflected light of the right light source light at the top of the grating are parallel, and the reflected light of the left light source light at the top of the grating and the right light source light at the trough of the grating. The reflected light is also parallel. Even in the case of diffused light, left and right light are paired and emitted in parallel within this range to be evenly mixed. The relationship between the incident light inclination α, the top inclination α, and the valley inclination β for determining the radiation angle γ from the vertical direction is shown in Equation 3 and FIG.

For a radiation angle γ = 6 °, α = 28 °, β = 34 °,
At the radiation angle γ = 30 °, α = 20 ° and β = 50 °. In addition to the radiation angle γ, the illumination device needs to add an error angle θ due to the light emitting element size.
By forming a curved reflection surface in the major axis direction, the radiation angle δ in the major axis direction can be controlled. The radius of curvature R in the major axis direction of the strip-shaped reflecting surface is expressed by the following equation 4 where L is the length of the strip-shaped reflecting surface in the major axis direction.

The curvature circle in contact with the parabola is approximated to a parabola as long as it is in a narrow range to the vicinity of the focal point in the optical axis direction. Therefore, it can be approximated not only by a parabolic mirror but also by a parabolic approximate spherical mirror that is easy to polish. Since the light emitting element is resin-molded for protection from moisture or the like, if a mirror surface is provided on the outer surface of the mold, the reflecting mirror and the focal point are integrated, so that the focal position adjustment is not necessary.
In the case of an elliptical mirror or a hyperbolic mirror, the ridge line of the grating becomes a curve, and a curved reflection grating can be formed by combining the elliptical mirror 8 and the hyperbolic mirror 9. FIG. 7 shows an annular reflection grating using a large number of pairs of elliptical mirrors and hyperbolic mirrors. Suitable for small-diameter annular illumination devices such as microscope illumination, medical illumination, and downlight. When the diameter of the ring is large, it can be approximated by the reflection grating of FIG. 1 or FIG.

FIG. 8 shows a structure in which a translucent opening is provided at the bottom of the inclined reflecting surface in order to mix the three colors using a triangular wave lattice. In order to prevent the inclined light from hitting the opening, the inclination θs of the reflecting surface needs to be 35.3 ° according to Equation 5.

Since the inclination θr of incident light is 19.5 °, the dimension in the thickness direction of the light source part to be converted into parallel light becomes large, but it is suitable for a projector or the like in which the dimension of the light source part in front is not affected.

When the number of pixels is large as in a liquid crystal display device, the light source section becomes very thick with the above configuration. When the grating reflecting surface is formed by the convex reflecting surface 5 and the luminous flux is enlarged to the pixel width, the curved surface length sub-pixel width of the convex reflecting surface is divided by the luminous flux enlargement ratio. FIG. 9 shows a state in which the parallel light expands the light flux on the convex reflection surface and expands to the width W of the transmission portion of the sub-pixel on the irradiated surface. The distance t to the irradiated surface is the sum of the light guide plate thickness and the liquid crystal transparent substrate thickness, where the width of the transmissive part of the subpixel is W, and the curved surface length along the circumference of the light guide plate convex inclined part is d. The radius of curvature r of the convex reflecting surface is expressed by Equation 6.

The inclination θi of the incident light can be obtained from Equation 7 from the step s and the pixel width X.

When the step is 10 μm and the pixel width is 400 μm, θi is 1.43 °, which can be relaxed to 1/13 of the above 19.5 °, so that the light source portion can be made thinner. Thinning enables a light guide plate and makes it possible to use total reflection by a convex reflection surface, so that mirror formation is unnecessary. FIG. 10 shows a structure in which a convex reflection surface facing a light source in two directions is provided for each pixel width. Since the main part is enlarged, θi is displayed larger than 1.43 °. Although FIG. 10 is composed of two light guide plates, each light guide plate is composed of a convex reflecting surface facing a light source in two directions. Three or more colors can be mixed by transmitting different color light to the horizontal plane between the pitches of the convex reflecting surfaces, and FIG. 10 shows a state in which the four colors are mixed by disposing the same light guide plate. This is shown when a convex refracting surface is provided on the light guide plate exit surface to return to parallel light.

FIG. 11 shows a state in which three colors are supplied to the sub-pixels of the liquid crystal display device and mixed. 10 and FIG. 11, two light guide plates are used. If these elements are integrated, a three-color stripe can be realized with one light guide plate as shown in FIG. A single light guide plate eliminates the need for pixel alignment, improves productivity, and halves material costs. The main part of FIG. 12 is expanded and demonstrated in FIG.
The light of the thin line incident on the first sub-pixel 27A that constitutes a pixel by three sub-pixels is incident on the central convex reflection surface 5A beyond the upper end of the right-side convex reflection surface 5. The light is totally reflected by the convex reflection surface, and the luminous flux is enlarged and irradiated to the sub-pixel width. The broken line light enters the left convex reflection surface, expands the light beam, and enters the second subpixel, and the third color light enters from the lower part of the light guide plate. The incident part protruding to the lower part of the light guide plate constitutes a surface perpendicular to the incident light beam, and the rear surface of the projection part is the convex reflection surface 5C to irradiate the third pixel with a luminous flux. If a reflective surface symmetrical to the 5C surface is formed, four-color display is also possible.

  All the proposals for mixing three colors of light emitting diodes are insufficient due to asymmetry, but when reflecting parallel light in three directions on a triangular pyramid reflecting surface with an inclination of 30 ° in the vertical direction, a delta arrangement with an equilateral triangle arrangement Can be mixed and emitted. The regular triangular triangular pyramid with an inclination of 30 ° is composed of a convex shape and a concave shape, the top of the convex triangular pyramid is indicated by ○, and the valley portion of the concave triangular pyramid is indicated by ●, the shape of the inclined surface facing three directions is shown in the figure 14 is a combination of diamonds. The light sources that irradiate the triangular pyramid reflection surface are arranged in three directions as shown in FIG. 14 and are arranged to irradiate 30 ° downward on the horizontal plane. It is a structure that is not obstructed by. Since the same inclined surface as that of the triangular wave lattice, the mixed color light of the three colors is emitted as parallel light in the direction perpendicular to the paper surface, so that it can be used as a light source of a three primary color display device.

The triangular wave grating is not limited to color mixing as a reflective surface, but can also be composed of a refractive surface. FIG. 15 shows a state in which light is incident from two directions and is refracted by a surface configured in a triangular wave shape and emitted as parallel light.
With the refractive index n2 of the refractive grating constituent material and the refractive index n1 of the surrounding medium, the light incident on the V-shaped right inclined surface from the right light source at an angle α is refracted at an angle β by Equation 8. Since the angle of the inclined surface of the V-shaped groove is γ with respect to the center line and is incident in parallel to the opposing refracting surface, the right-side light source light is incident only on the right-side inclined surface. It is the same. By setting the inclined surface angle γ of the V-shaped groove by the difference between β and α as shown in Equation 8, both refracted lights are emitted parallel to the center line. When entering the horizontal surface of the refractive grating symmetrically from the left and right at an angle δ, the light enters the refracting surface at an angle α and is mixed to be emitted as parallel light.


Α, β, γ, and δ in polymethyl methacrylate and polycarbonate, which are typical light-transmitting polymers, are shown.

The color mixture due to refraction has a shape that is long in the traveling direction as shown in FIG. 16 due to the restriction of the refractive index. However, since the light source part is on the back side of the grating surface, the entire surface can be displayed uniformly as in the embodiment of FIG. Refractive gratings can be stacked in the direction of travel, so they can be mixed in four or six directions by combining with a reflective type. A four-way mixing device is shown in FIGS. 17 and 18, and an eight-way mixing device is shown in FIGS.

In order to obtain a continuous spectrum with an individual light emitting element, the wavelength width at which the luminous intensity of the light emitting diode reaches about half the peak is 20 nm to 60 nm. Covering can achieve continuous spectrum white light.
By combining the reflection type and the refraction type, eight colors can be mixed by the structure as shown in FIGS. 19 and 20, and since it is not a color mixture due to scattering, it is possible to irradiate white light with a narrow emission angle. Although multi-color mixing is also possible with the light guide plate shown in FIG. 10, in FIG. 20, since a substrate on which four pairs of reflection gratings are mounted can be used as a radiator, heat dissipation is easy. When eight colors are mixed, white light having a continuous spectrum can be synthesized as shown in FIG.

When a fluorescent white light emitting diode is broadened by mixing a plurality of phosphors, the fluorescence is absorbed by other phosphors by mixing a large amount of phosphors, and the efficiency further decreases. If all the bands are converted to fluorescence with a single light emitting element, conversion efficiency is increased. For this reason, a method of mixing colors using a reflection grating instead of mixing phosphors is shown below.
When the first light-emitting element is a blue light-emitting diode and the phosphor is dispersed so that the peak value of the yellow phosphor is about half of the peak value of the blue light, the blue-green has a dip and the red region is lowered. It is a characteristic.
The second light-emitting element is a blue-green light-emitting diode that emits light at the dip wavelength of the first light-emitting element, and when the phosphor is dispersed so that the peak value by the orange phosphor has a double peak characteristic that is about half of the blue-green light peak value. This is a characteristic with a dip in green.
When the first light-emitting diode light and the second light-emitting diode light are additively mixed using the reflection grating shown in FIG. 1 or FIG. 3, the blue-green dip of the first light-emitting diode is complemented with the blue-green light of the second light-emitting diode. .
Since the fluorescence spectrum of the first light-emitting diode and the fluorescence spectrum of the second light-emitting diode are broad, yellow, which is an intermediate wavelength between them, is added approximately evenly by additive color mixing, resulting in a high peak value, and green light is the first light-emitting diode. The light is mainly supplemented by the second light emitting diode light. The red light is mainly supplemented by the first light emitting diode light, mainly the second light emitting diode light, and the peak value is approximately equal to that of the excitation light from the green to the red range, so that a gentle continuous spectrum of fluorescence can be obtained. The spectral characteristics before and after synthesis are shown in FIG. Continuous spectrum white light can be realized by a lattice-shaped color mixing element and two types of fluorescence conversion light emitting elements. The method of obtaining a broadband characteristic with a phosphor decreases in efficiency, but if a light emitting diode having a light emission wavelength in a region where the two-peak characteristic is insufficient is not compensated for fluorescence conversion efficiency, a continuous wavelength can be realized with high efficiency.

Color spots were caused by the asymmetry of the distance and angle between multiple light emitting elements and reflectors, but they were mixed using a reflective or refractive grating to prevent mixing of different light sources and emitted at the same radiation angle. By doing so, color spots can be prevented.
By making the reflection grating a convex reflection surface, the inclination of incident light can be reduced and the light source portion can be made thinner. Since the total reflection using the light guide plate can be utilized by reducing the thickness, it is not necessary to form a mirror surface and the productivity is improved.
Since the three-color stripe can be realized with one light guide plate by the structure in which the convex reflection surface grating is directed in three directions, alignment is not required, productivity is improved, and material cost can be reduced.
The spectrum of fluorescent white light-emitting diodes consists of two peaks of sharp blue and a gentle yellow range. By using a color mixing device that does not cause color spots, multiple excitation lights can be used, resulting in high efficiency. A continuous spectrum can be realized.
By mixing colors with a reflection grating or a refraction grating, white light with a continuous spectrum can be obtained with higher efficiency than a method in which phosphors are mixed in a multi-component system to broaden the spectrum.

For the convenience of explanation, the main part is enlarged and displayed, so the relationship is not necessarily similar.
Side view of triangular wave reflection grating Plan view of triangular wave reflection grating Radiation angle error due to light source dimensions Dependence of radiation angle error on reflector y position Side view of triangular wave convex reflection grating Top slope / valley slope and radiation angle Annular illuminator using elliptic mirror / hyperbolic mirror light source Three-color stripe display device using both reflection grating and transmission part Beam expansion by convex reflecting surface Multi-color striped light guide plate using convex reflective surface grating and transmissive part Two-layered three-color striped light guide plate using a convex reflecting surface grating and a transmission part One-color three-color striped light guide plate in which a convex reflecting surface grating is arranged on the bottom side of the light guide plate The main part of a single-color three-color striped light guide plate Convex and concave portions of triangular pyramid dot array grid Color mixing by triangular wave refracting surface grating Color mixing device with triangular wave refractive surface grating Plan view of a four-color mixing device using a catadioptric grating Side view of a four-color mixing device using a catadioptric grating Side view of 8-color mixing device with catadioptric grating Perspective view of 8-color mixing device with catadioptric grating Spectrum of 8-color mixed white light source with catadioptric grating Synthetic spectrum by color mixture of two kinds of fluorescent white light emitting elements Traffic signal display surface with refractive grating Traffic signal display surface with reflection grid Cross section of convex grid unit Front view of vehicle headlamp Schematic diagram showing only forward scattered light in a conventional color mixing device with a conical scattering surface A conventional package that mixes colors by relieving color spots by tilting the reflector near the chip A light guide plate with three layers that totally reflect in the direction of the liquid crystal panel at the 45 ° groove interface Conventional example in which three-color light is supplied to a liquid crystal stripe by a laminated light guide having a stripe width Conventional example of irradiating a predetermined pixel with three-color light by an inclined surface of a quadrangular pyramid provided on a light guide plate Three-color liquid crystal display device with terraced convex light guide plate and stripe distribution element

Example 1
FIG. 12 shows an illuminating device for a liquid crystal display device that mixes three-color stripes with reflecting surfaces arranged in a lattice pattern, and FIG. When the diagonal size is 510 mm (20.1 type) and XGA (1024 × 768), the screen dimensions are 408 mm wide, 306 mm long, pixel pitch 399 μm, and subpixel pitch 133 μm.
The three types of convex reflecting surfaces facing three directions have a structure in which 1024 steps are evenly arranged at a pixel pitch. Since the step of the convex reflection surface of the light guide plate is smaller than the pixel size, it is enlarged to the pixel size. However, since the thickness of the light guide plate is constant, the radius of curvature of the convex reflection surface is constant. When the light guide plate thickness t is 10 mm and the step s of the convex reflection surface is 10 μm, the radius of curvature r is 159 μm. Reflecting parallel light rays from the light source toward the sub-pixels of the liquid crystal in the substantially vertical direction. By tilting beyond the total reflection critical angle, it is not necessary to form a reflective layer, and manufacturing costs can be reduced.
The light emitting diode is offset from the focal point of the parabolic mirror of the light source unit at a position where the reflected light of the parabolic mirror is not blocked. By arranging 128 light emitting diodes each having a luminous intensity of 250 mcd, a luminance of 307 cd / m 2 can be obtained when the light transmittance is 40%.
As the transparent material, polymethyl methacrylate, alicyclic acrylic resin, cyclic olefin resin, polycarbonate, photocured acrylic resin, and the like can be used, which can be molded by injection compression molding or the like. Since the photo-curing acrylic resin is polymerized from a low-viscosity monomer or oligomer as a starting material, it can be precisely molded.

Example 2
As an example in which two colors of parallel light are incident on a grating reflecting surface or a grating refracting surface to mix colors, a signal device that synthesizes yellow using a red light emitting diode and a green light emitting diode is used. Example 3 will be described in Example 3. Although it is called a green light, it is green. It is displayed in bluish green as a measure against color blindness. The yellow signal is displayed in orange-yellow with an orange color.
A red light-emitting element 620 nm ± 10 nm and a green light-emitting element 515 nm ± 10 nm are provided at the focal point of the parabolic mirror in FIG. 16, and two colors of driving current are set for chromaticity and luminance on the chromaticity coordinates to irradiate the refractive surface grating. In addition, a yellow color of 570 nm ± 10 nm can be displayed. When a blue-green light-emitting diode of 500 nm or less is used and mixed with a red light-emitting diode, a straight line on the chromaticity coordinate approaches a white region and becomes pale yellow, so a green light-emitting diode of 515 nm ± 10 nm is used. As a result, since the color mixture line is along the right edge surface of the chromaticity coordinates having a horseshoe shape, a deep yellow color can be mixed.
Conventional traffic lights have wide directivity, so not only can you see the signals on the intersecting road side, but they also radiate to the sky, so the current consumption has increased, but if you set the required directivity range, the current consumption will be reduced. Further, the manufacturing cost can be reduced by reducing the number of elements. Directivity to irradiate up to the sky or intersecting roads consumes current consumption, but if the vertical radiation range is below the horizontal plane and the horizontal radiation angle is within ± 45 °, the current consumption is reduced to about 1/4. I can do it. For this reason, even if the red and green elements are provided in half on one display surface, the necessary light quantity can be obtained. In recent years, the luminous efficiency has been remarkably improved. However, since the dots of the light emitting elements are conspicuous on the conventional display surface, if the number of elements is reduced, the display becomes more rough, so it is difficult to reduce the number of elements. However, the refraction grating is displayed in such a width that the comb shape cannot be recognized, and since the light source part is on the back side of the display surface, the whole is displayed uniformly. For this reason, the number of light emitting elements can be reduced according to directivity control and light emission efficiency.
If the diameter of the unit shown in FIG. 16 is 25 mm, about 120 units can be arranged on the 300 mm diameter display surface shown in FIG. When eight pairs of refraction gratings are provided, one side has a comb shape with a width of 1.5 mm, and when red or green is displayed, the light is emitted from one side of the grating in a comb shape. When red light and green light are emitted from a refractive grating having a width of 1.5 mm, the grating cannot be recognized due to the distance to the traffic signal display surface, and color spots do not occur due to coincidence of the radiation directions. The means for emitting diffused light within the required directivity range is a concave lens array shown in FIG. The concave lens array also functions as a hood that is both dustproof and waterproof.
In the conventional three-lamp traffic light, there is a pseudo-lighting phenomenon in which two non-lighted lights are brightened due to sunlight and the brightness difference decreases, but the mixed lighting by the refractive grating does not cause the pseudo-lighting phenomenon because the display surface is one light, The number of yellow light emitting elements can be reduced, and the number of elements can be reduced by controlling the directivity.

Example 3
A signal device that combines a red light emitting diode and a blue-green light emitting diode with yellow using a reflection grating will be described with respect to differences from the second embodiment. If the reflection grating surface of the unit shown in FIG. 5 is 19 mm square, about 120 units can be arranged on the display surface having a diameter of 300 mm shown in FIG. When eight pairs of reflection gratings are provided, a convex reflection surface having a width of 1.5 mm is formed on one side surface, and in a red or green display, light is emitted in a comb shape from one side surface of the grating. When red light and green light are emitted from a reflection grating having a width of 1.5 mm, the grating cannot be recognized due to the distance to the traffic signal display surface, and color spots do not occur due to the coincidence of the radiation directions.
The reflection grating expands the directivity by the curved reflection surface and has the directivity to which the radiation angle derived from the light emitting element size is added, but the directivity can be set by bending the installation surface of the reflection grating. Therefore, the directivity according to the road condition can be set by the curved installation surface of the reflection grating. The directivity control is characterized by a greater degree of freedom than the refraction type. Since the reflection grating type has a structure in which the light source parts are arranged, the space factor of the reflection surface is 60%. The dot of the light emitting element is conspicuous on the display surface of a conventional traffic light using a bullet-type light emitting diode because only the vicinity of the tip shines from the lens shape, and the area ratio occupied by the bright portion is about 50%. For this reason, it is the space factor of the brightness | luminance part more than equivalent to the past.

Example 4
A vehicle headlamp will be described as an embodiment in which a reflection grating using a convex reflection surface is used and a radiation angle is varied in the orthogonal direction of the grating. The light source is a white light source that covers a visible light range by mixing a fluorescent white light emitting diode using a yellow phosphor as a blue light emitting diode and a fluorescent white light emitting diode using an orange phosphor as a blue green light emitting diode. It can be applied to spotlights by changing the radiation angle.
If the emission angle in the vertical direction of the vehicle headlamp is 10 ° and an error angle of about 4 ° due to the light source size is subtracted, the emission angle γ in the direction perpendicular to the reflection grating is 6 °. From Equation 3, the tilted light and the top slope α are 28 °, and the valley slope β is 34 °. Assuming that the radiation angle parallel to the reflection grating is 20 ° and the length of the reflection grating strip is 14 mm, the radius of curvature is 40 mm from Equation 4. FIG. 25 shows a cross-sectional view of the four pairs of convex reflecting surface lattice configurations, and FIG. 26 shows a front view of the vehicle headlamp.
One of the left and right light source units is a fluorescent white light emitting diode using a yellow phosphor as a blue light emitting diode, and the other is a fluorescent white light emitting diode using an orange phosphor as a blue green light emitting diode.
A light emitting element is provided at one focal point of the elliptical mirror, and a phosphor is provided at the other focal point. Fluorescence is emitted from the phosphor receiving the excitation light to the rear and front paraboloid mirrors, and the parallel light from the rear paraboloid mirrors is redirected by the plane mirror to irradiate the parallel light in the direction of the reflection grating.
When a forward current of 40 mA is applied to the light emitting element, one unit consisting of two light sources gives 0.28 W, and this unit uses 11 units horizontally and 8 columns vertically, using a total of 88 units, with a conversion efficiency of 60 lm / W and 1480 lm. A luminous flux can be obtained. The dimensions are 160 mm in width and 170 mm in length. The mixed spectrum is shown in FIG.
In the case of a passing beam, if the lower five rows are turned on, the light intensity becomes 920 lm. If a cut-off line is provided in the unit arrangement as shown in FIG. 28, the antiglare effect on the oncoming vehicle can be increased. The oblique reflection grating in the cut-off line is a trapezoidal reflection grating that combines an elliptical mirror and a hyperbolic mirror. FIG. 28 is a front view of the case of a left-side traveling vehicle, and shows the state of the passing beam with the upper three steps turned off.
The reflection grating can also be used as a heat sink when a metal mirror surface such as aluminum is used. The total loss of the traveling beam with the above configuration is 24.6W. When a mounting space having a width of 30 mm is provided around the reflection grating array, the dimensions of the heat sink are 220 mm wide and 230 mm long.
When a duct is provided behind the heat radiating plate and cooled by traveling wind or forced convection at wind speed u = 10 m / s (36 km / h) or more, the temperature rise is about 25 ° C. according to Equation 9. Since the heat conduction from the heat radiating plate to the entire wall surface of the duct can be used for heat radiation, the temperature rise can be lowered below about 28 ° C. Since Equation 9 uses the physical property value of air at the heat sink temperature, it must be repeatedly calculated, but the physical property value Prandtl number at 50 ° C. near the convergence condition Pr: 0.71
Thermal conductivity λ: 0.0241 [W / m ° C.]
Kinematic viscosity coefficient ν: 1.86 × 10 −5 [m 2 / s]
Are used to obtain the Reynolds number Re, the Nusselt number Nu, the average heat transfer coefficient α, and the temperature rise T. The vertical dimension L and horizontal dimension W of the heat sink are set, and the outside air temperature is 20 ° C.

Example 5
An embodiment of an annular downlight will be described by forming an annular reflecting grating shown in FIG. 7 using a number of combinations of elliptical mirrors and hyperbolic mirrors.
Since the downlight has an emission angle of about ± 30 °, the reflection grating has a convex mirror configuration. If 32 pairs of elliptical mirrors and hyperbolic mirrors are used for the outer shape with a diameter of 120 mm and a forward current of 40 mA is passed through the light emitting element, the light intensity becomes 32 W with 32 pairs of light sources. When direct light from the light emitting element is incident on the annular reflection grating, the color mixing characteristics are deteriorated. Therefore, the light emitting element is provided at the focal point of the off-axis elliptical mirror and the off-axis hyperbolic mirror.
One of the paired light source units is a fluorescent white light emitting diode using a yellow phosphor as a blue light emitting diode, and the other is a fluorescent white light emitting diode using an orange phosphor as a blue green light emitting diode. The mixed spectrum is shown in FIG. It is a thing.

Example 6
An embodiment of a white light source in which eight colors are mixed by the structure shown in FIGS. 17, 19, and 20 using the reflection type and the refraction type will be described.
The triangular wave-like reflection grating is provided with 10 pairs of gratings on a reflection surface having a width of 10 mm and a length of 10 mm. When eight color light emitting elements are used for four reflection grating units and mixed through a refractive grating with an apex angle of 53.2 ° made of polymethylmethacrylate twice, white light having a continuous spectrum is synthesized as shown in FIG. I can do it. Since the visible light region has a hindrance close to white light of 5500K, it is suitable for applications requiring high color reproducibility, and since it does not contain infrared rays, temperature rise can be avoided and damage due to ultraviolet rays can be avoided.

1: light emitting element 2: concave mirror around light emitting element 3: fluorescent reflecting concave mirror 4: triangular wave reflecting grating 5: convex reflecting grating 6: parabolic mirror 7: phosphor film 8: elliptical mirror 9: hyperbolic mirror 10: convex refractive surface 11: concave refracting surface 12: fluorescent particle 15: refractive grating 16: excitation light 17: fluorescent 18: translucent material 19: parallel light 20: diffused light 21: concave mirror 22: convex mirror 23: opening 24: light guide plate 25: plane mirror 26: Shading body 27: Subpixel 28: Liquid crystal sandwich substrate 29: Substrate 30: Circuit board 31: Valley portion 32: Top portion 33: Ellipse 34: Air layer 37: Incident surface 38: Support member 39: Scattering surface 40: Focal point 41 : Stripe distribution element 42: Groove 43: Square pyramid 44: Cut-off line

Claims (9)

  A reflection surface or a refracting surface is arranged in a wavy structure with an inclination angle at which light from other light sources does not enter to form a grating, and the light from multiple light sources has an emission direction and a radiation angle depending on the shape of the reflecting surface or the refracting surface. A lighting device characterized by mixing and mixing. A plane reflecting surface is arranged in a triangular wave shape with an inclination of 30 ° to constitute a grating reflecting surface,
The reflected light incident from one light source side of the triangular wave reflecting surface and the reflected light incident from the other light source side of the triangular wave reflecting surface are emitted in the same direction and mixed. Lighting device. A curved reflection surface is arranged in a triangular wave to form a lattice reflection surface,
The reflected light incident from one light source side of the triangular wave reflecting surface and the reflected light incident from the other light source side of the triangular wave reflecting surface are mixed in the same direction to emit diffused light or convergent light. The lighting device according to claim 1.   2. The light source unit according to claim 1, wherein the light source portion is thinned by reducing the inclination of incident light by reducing the step of the reflection surface to be smaller than the sub-pixel width by the light beam expanding function of the curved reflection surface. Lighting device. A plurality of convex reflective surfaces are formed on the light guide plate at a pixel pitch to form a grid-like reflective surface,
The lighting device according to claim 1, wherein color mixing of three or more color lights is performed by transmitting different color light between the pitches of the convex reflection surfaces. Constructing a grating refracting surface that emits from the high refractive index side to the low refractive index side by arranging in a triangular wave with an inclination of the incident angle and the outgoing angle difference,
2. The illumination device according to claim 1, wherein incident light from one light source side and incident light from the other light source side are refracted and emitted in the same direction on a triangular wave refracting surface and mixed.   In a traffic signal device, a red light emitting element 620 nm ± 10 nm and a green light emitting element 515 nm ± 10 nm are provided at the focal point of a light source unit forming a pair of a refractive surface grating or a reflecting surface grating, and irradiated to the refractive surface grating or the reflecting surface grating to 570 nm by color mixing. The illumination device according to claim 1, which emits yellow mixed light of ± 10 nm.   Complementing the intermediate range between the excitation wavelength and the fluorescence wavelength using a plurality of light emitting elements having different excitation wavelengths, and adding the peak values in the fluorescence range, the excitation light and the fluorescence peak values are evenly mixed. The lighting device according to claim 1.    2. The illumination according to claim 1, wherein in the vehicle headlamp, an elliptical mirror and a hyperbolic mirror are combined to form a trapezoidal reflection grating, and an oblique cut-off line is combined with the rectangular reflection grating. apparatus.