JP4681075B1 - Illumination device and display device - Google Patents

Abstract

Since the color mixing due to scattering is difficult to control the radiation angle and the efficiency is low, an illumination device and a display device that control the radiation angle and mix colors with high efficiency are realized.
One diagonal line of a rhomboid refracting surface is provided on the reference plane, and adjacent sides of the rhomboid refracting surface above and below the reference plane diagonal line are arranged in contact with each other to form a convex and concave triangular pyramidal refraction grating 4. The angle of inclination between the rhomboid refracting surface and the normal of the reference surface is set as the difference angle γ between the incident angle α and the refracting angle β on the refracting surface, and the parallel light from the three-way parallel light source is used as the light source. The light is incident only on the refracting surface on the opposite side, refracted vertically above the reference surface, and mixed by matching the emission direction.
A liquid crystal display device having a structure in which a triangular pyramid refraction grating 4 is formed on the exit surface of the light guide plate and a convex reflection surface 5 is formed on the bottom surface of the light guide plate so that parallel light is incident on the convex reflection surface from the side surface of the light guide plate. The light beam is magnified and reflected by the triangular pyramid refraction grating to irradiate the sub-pixel, and the parallel light of three colors from three directions is irradiated to the pixel composed of the rhomboid sub-pixel.
[Selection] FIG.

Description

  The present invention relates to an illuminating device and a display device in which light emission from three or more colors of light emitting elements is controlled by a reflecting element or a refracting element configured in a triangular pyramid lattice to improve the color mixing characteristics.

Semiconductor light emitting devices are widely used in various display devices and lighting devices because of their excellent features such as small size, high efficiency, long life, low voltage operation, and high speed response.
The liquid crystal display device can use three primary color lights using three color light emitting elements in order to display an intermediate color by a control signal of three colors even in a discontinuous spectrum by three primary color light emitting elements of red, green, and blue. In the proposal (FIG. 24, Patent Document 1) in which light emitting elements of three colors are provided on the inner surface of the cone and the color mixing distance is increased by backscattering, absorption due to multiple reflection increases and efficiency decreases. There is a proposal to reduce the difference in the distance and angle between each light emitting element and the reflecting mirror by placing three color light emitting elements in the same package and steeply tilting the reflecting mirror in a portion near the light emitting element (FIG. 25, 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 range and a large dip in green. However, since the fluorescent white light emitting diode can be easily manufactured as compared with the mixed color of the three primary colors, the fluorescent white light emitting diode is used as a backlight of a liquid crystal display device such as a mobile phone, an LED bulb, and the like.

With the improvement of the light emission efficiency of semiconductor light emitting devices, the application to illumination by light emitting diodes that can be made smaller than fluorescent lamps is progressing. Since the light emitting diode has a small allowable temperature rise compared to other light sources, it requires a large number of chips to obtain a large luminous flux, and is expensive. Therefore, 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 the white light backlight source is separated into three colors by the color filter, 2/3 light amount is absorbed by the color filter and the efficiency is lowered. 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. There is a proposal (FIG. 26, 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. 27, 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. 28, 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. 29, Patent Document 7).
Two colors of light are incident on the bottom surface of the prism having an apex angle and a valley angle of 90 ° from two directions, and the light incident on the inclined surface having a large incident angle is emitted by mixing the refracted light in the same direction. The light incident on the inclined surface having a large incident angle exceeds the critical angle and is totally reflected, and returns to the other light source. In order to utilize the returning light beam, a structure for emitting light from another light source side using a band pass mirror has been proposed (FIG. 32, Patent Document 8).

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 full width at half maximum 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 Japanese Patent No. 4114173 JP 2008-218154 A

The proposal of Patent Document 1 in which three color light emitting elements are arranged in the same package and the colors are mixed by a structure such as steep inclination of the reflecting mirror in the vicinity of the light emitting element is different in distance and angle from each light emitting element to the reflecting mirror. This produces color spots that follow the tip. Since color mixing by regular reflection is difficult, color mixing such as back scattering by the scattering layer on the inner surface of the cone to increase the scattering distance causes the reflected light to return to the light source side and be absorbed during multiple reflections, thereby reducing efficiency.

  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 (Patent Document 3). ). 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 fluorescent material is absorbed because it is colored and opaque and has a low fluorescence conversion rate with respect to the fluorescence wavelength. Increasing the phosphor blending ratio by compensating for absorption further reduces the efficiency. Fluorescent white light emitting diodes are bluish-white light with a high blue light spectrum given priority to efficiency, and an average color rendering index of about 70, which is low color rendering.

When mixing phosphors having a wide wavelength band in order to improve color rendering, it is necessary to mix them at a blending ratio of the phosphors according to 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 of Patent Document 4 requires a thickness of 1/3 of the screen width to provide a 45 ° inclination and the number of sub-pixels. A screen width of 300 mm requires a thickness of 100 mm per layer of the light guide plate. It becomes expensive due to the man-hours for processing.

Patent Document 5 proposes that a light-shielding layer is provided at the interface between a plurality of rod-shaped light guides, light of each color 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 is difficult to bundle and manufacture a light guide member having a sub-pixel width subjected to a light shielding process. 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.

The proposal of Patent Document 6 in which a light guide plate is provided with a large number of reflectors made of a quadrangular pyramid and reflects and mixes the three primary color lights from three directions to the pixels, and only a reverse V-shaped reflected light is obtained by being blocked by the front quadrangular pyramid. However, when oblique parallel light is irradiated onto the quadrangular pyramid, it also hits the side surface, so that it becomes scattered light and enters other pixels and becomes unclear.

  The proposal of Patent Document 7 in which a light guide plate having a convex reflection surface arranged in a terraced shape and a reflection / transmission element distributes stripes uses two types of light guide elements having different structures, and therefore requires accurate alignment.

The incident light is incident on both of the pair of inclined refracting surfaces, and the light incident on the other refracting surface forming a pair is incident on the critical angle when the light is refracted by one inclined refracting surface and emitted in the vertical direction of the bottom surface. Thus, the light is totally reflected and returned to the other light source side. If total reflected light is rereflected by a bandpass mirror and used, loss can be avoided, but it is complicated and expensive.

The strip-shaped reflecting surface is arranged on the reference plane with the major axis direction orthogonal to the traveling direction of the parallel light from the light source, and the minor axis direction of the strip-shaped reflecting surface is alternately inclined by ± 30 ° to form a triangular wave 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 parallel light of the light source facing the reflecting surface is incident on the reflecting surface, the light incident from both sides is reflected vertically upward.
Assuming that the inclination of the triangular wave lattice 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 inclinations α and β are 30 ° as shown in Equation 1.

The reflected light from the left and right parallel light sources is a reflected light in which all of the reflected lights are in a comb shape according to the reflecting 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.

Similarly to the case where the reflected light from the right and left parallel light sources is combined and mixed by the reflected light alternately arranged in a comb shape, it is positive when the parallel light in three directions is reflected in the vertical direction on the triangular pyramid reflecting surface with an inclination of 30 °. The light is mixed and emitted in a delta arrangement with a triangular arrangement. The light sources that irradiate the triangular pyramid reflecting surface are arranged in three directions as shown in FIG. 2 and are arranged to irradiate 30 ° downward toward the reference surface. The structure is not obstructed by the triangular pyramid. 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 vertical direction of the reference surface, so that it can be used as a light source of a three primary color display device. When the triangular pyramid is composed of a convex shape and a concave shape, the upper and lower triangles are connected, and the shape of the inclined surface facing three directions is a combination of rhombuses as shown in FIG. In FIG. 3, the reference surface of the triangular pyramid is indicated by a broken line, the top of the convex triangular pyramid is indicated by ◯, and the valley of the concave triangular pyramid is indicated by ●.

The triangular wave grating can be constituted by a refracting surface, and FIG. 3 shows a state in which light is incident from two directions and is refracted by a surface formed 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 from the right light source onto the right inclined surface of the refractive grating at the incident angle α is refracted at the refractive angle β according to Snell's law of Equation 2 (1). . Since the angle of the inclined surface of the triangular wave refraction grating is parallel to the pair of refracting surfaces as γ with respect to the center line, the right light source light is incident only on the right inclined surface, and since the inclined surface and the incident light are symmetrical, the left light source The same applies to light. By setting the inclined surface angle γ of the triangular wave refractive grating by the difference between β and α as shown in Equation 2 (2), 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.

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

If the refractive grating is formed of a triangular pyramid and the emission directions are made coincident, light from three directions can be mixed as shown in FIG. The three inclined surface angles of the triangular pyramid are all γ with respect to the center line, and the incident angle between the parallel light from the three directions and the bottom surface is δ. The light refracted at the bottom surface is incident on only one surface in the traveling direction and is not incident because it is parallel to the other two surfaces. In FIG. 4, the parallel light A from the light source A arranged on the right side is refracted on the bottom surface, then enters the left refracting surface of the triangular pyramid at an incident angle α, is refracted in the vertical direction, and exits, and is arranged on the back left side. After the parallel light B from the light source B is refracted on the bottom surface, the light is refracted in the vertical direction on the right refractive surface of the triangular pyramid and emitted, and the parallel light C from the light source C arranged on the left front side is refracted on the bottom surface. The light is refracted in the vertical direction on the refractive surface at the back of the triangular pyramid and emitted. The refracting surface on the back side is shaded in FIG.

When a plurality of triangular pyramids are arranged in the same direction on the reference plane, the parallel light in the three directions is refracted and mixed in the vertical direction on the triangular pyramid refracting surface, but is emitted in the opposite direction to the direction of the triangular pyramids on the reference plane. A triangular space pointing in the direction is created. Even if a convex triangular pyramid is provided in this space, the refracted light cannot be emitted in the vertical direction. In this space, a concave triangular pyramid recessed from the reference plane is provided. When the convex triangular pyramid and the concave triangular pyramid are used, the upper and lower triangles are connected, and the shape of the inclined refractive surface is a combination of diamonds as shown in FIG. It is. In other words, one diagonal line of the rhomboid refracting surface is provided on the reference plane, and the adjacent sides of the rhomboid refracting surface above the diagonal line on the reference plane are arranged in contact with each other to form a convex triangular pyramid refraction grating above the reference plane. A concave triangular pyramid refraction grating that is recessed from the reference plane is formed by adjoining adjacent sides of the rhomboid refractive surface below the diagonal line, and the rhomboid refractive surface is the difference between the incident angle on the refractive surface and the refraction angle Is a structure in which the inclination angle formed by the normal to the reference plane is set, the triangular pyramid refraction grating is made of a material having a higher refractive index than the surrounding medium, and is emitted from the high refractive index side to the low refractive index side. The parallel light from the three-direction parallel light sources can enter only the refracting surface on the side facing the light source and be refracted vertically above the reference surface, and can be mixed by matching the emission directions.
In FIG. 5, the bottom of the triangular pyramid is indicated by a broken line, the top of the convex triangular pyramid is indicated by ◯, and the valley of the concave triangular pyramid is indicated by ●. Although the shape of the refracting surface is a rhombus, it is called a triangular pyramid refraction grating 4 because it is a structure combining a convex triangular pyramid and a concave triangular pyramid. When the convex triangular pyramid and the concave triangular pyramid are used, it is possible to irradiate parallel light on the rhombus facing the parallel light without waste.
The light sources that irradiate the triangular pyramid refracting surface are arranged in three directions as shown in FIG. 4 and are radiated at the above-mentioned angle δ at the elevation angle toward the reference surface. The structure is not obstructed by the front triangular pyramid. Since mixed color light of three colors is emitted as parallel light in the direction perpendicular to the reference plane, it can be used as a light source for a three-primary color display device.

If the light incident on the refraction grating is parallel light, a large space is required to provide a plurality of parallel light sources on the back of the display device, but the triangular pyramid refraction grating is formed on the exit surface side of the sidelight light guide plate. The thinned structure will be described. When the triangular pyramid refraction grating 4 is formed on the exit surface side of the light guide plate, the convex reflection surface 5 is formed on the bottom surface of the light guide plate, and parallel light inclined with respect to the bottom surface from the side surface of the light guide plate is incident on the convex reflection surface 5 Then, the light beam is reflected and irradiated to the triangular pyramid refraction grating by expanding the light beam. FIG. 6 shows a state in which the parallel light is reflected by enlarging the light flux on the convex reflecting surface, refracted by the triangular pyramid refraction grating, and enlarged to the width W of the transmission part of the sub-pixel 27 on the irradiated surface. The light beam expansion rate is expanded from the curved surface length d along the circumference of the convex reflecting surface to the sub-pixel width W. The distance t to the irradiated surface is the sum of the light guide plate thickness and the liquid crystal sandwich substrate thickness, where W is the width of the transmissive portion of the sub-pixel, and d is the curved surface length along the circumference of the convex inclined portion of the light guide plate. The radius of curvature r of the convex reflecting surface is expressed by Equation 3.

The inclination θi of the incident light with respect to the bottom surface can be obtained from Equation 4 from the step s and the pixel width X.

When incident light of three colors from three directions is incident on the convex reflection surface, each of the light beams spreads and reflects, and is irradiated onto the rhomboid refraction surface of the triangular pyramid refraction grating, and is irradiated onto the sub-pixel. Since the diamond-shaped refracting surface refracts in a substantially vertical direction and exits, the length of the diagonal line orthogonal to the reference surface of the diamond-shaped refracting surface is equal to the sub-pixel width W above the triangular pyramid refraction grating. Since the rhomboid sub-pixel shapes are combined, the pixel shape is a hexagon.

In order to prevent the diffused light that expands the light beam from entering the other two surfaces constituting the triangular pyramid, it is not necessary to enter the other two surfaces in parallel or behind the other two surfaces. The light mixed under these conditions expands and emits the light beam according to the Snell law of Equation 2 (1). The light ray A in FIG. 8 travels parallel to the ridges of the other two surfaces constituting the triangular pyramid and is emitted in the vertical direction to the reference surface. Although it has a two-layer structure in which a convex refracting surface for converting light beam expanded light by the convex reflecting surface into parallel light is provided between the triangular pyramidal refraction grating, the angle of incidence on the triangular pyramid refraction grating can be made constant. As the radiation angle of the diffused light increases, the outgoing lights of the rays B, C, and D are outgoing lights that are inclined from the vertical direction. When the light enters the other two surfaces constituting the triangular pyramid, the light is totally reflected like a light ray E and is emitted in a direction different from Equation 2.

9 and 10 show cross sections of two faces in a triangular pyramid refraction grating. FIG. 9 shows a state in which the light beam is reflected by one cylindrical convex reflecting surface and irradiated to one column of sub-pixels, but a plurality of sub-pixel columns are formed from one cylindrical convex reflecting surface as shown in FIG. Can also be irradiated. The number of sub-pixel columns is not limited to an integer, and a fraction is also possible if the light from the next convex reflection surface is continuous. When the cylindrical convex reflection surface on the bottom surface of the light guide plate is formed with a smaller number of columns than the number of pixels and irradiation is performed on a plurality of subpixel columns from one cylindrical convex reflection surface, the column is irradiated on one subpixel column. However, since the size of the convex reflection surface is large and the number of columns of the cylindrical convex reflection surface can be reduced, the convex reflection surface facing three directions can be easily molded.
As the number of distribution to the plurality of sub-pixel columns increases, the light is inclined like rays B, C, and D in FIG. 8, so that the inclination of the emission surface is corrected according to Equation 2 (1) in order to make the emission direction vertical. It is necessary to keep the radiation angle so as not to enter the adjacent sub-pixels of other colors. Since the light rays B, C, and D in FIG. 8 are blocked by the valley and a blind spot is generated near the top and the amount of light is reduced, it is desirable to keep the radiation angle free from the influence of uneven brightness. The same applies to the case where the light guide plate thickness is reduced because the light guide plate is inclined like rays B, C, and D.

9 and 10 only show the two-direction component, FIG. 11 shows the three-direction component in a plan view. A mechanism for totally reflecting parallel light from the three directions in the direction of the triangular pyramid refraction on the convex reflection surface facing the three directions on the bottom surface of the light guide plate will be described. 11 is a triangular prism-like convex reflecting surface facing in two directions provided on the bottom surface of FIGS. 9 and 10. In FIG. 11, the line composed of one set of three extending in the horizontal direction is formed by forming a cylindrical convex reflecting surface provided in parallel with two sides facing the upper side and the lower side of the side surface of the light guide plate in the shape of a triangular prism and touching the top edge. It is. A cylindrical convex reflecting surface for reflecting parallel light B irradiated in the lower right direction of the figure in the direction of the rhomboid refraction grating is arranged on the bottom surface of the light guide plate, and parallel light C irradiated in the upper right direction of the figure is in the direction of the rhombus refraction grating The cylindrical convex reflecting surface that reflects the light beam forms a ridge, and the parallel light B that irradiates in the lower right direction of the figure and the parallel light C that irradiates in the upper right direction of the figure are reflected by the cylindrical convex reflecting surface that touches the top edge. Then, the light enters the triangular pyramid refraction grating and enters the sub-pixels B and C.
The light from the parallel light source A in the leftward direction is changed in the vertical direction by the diamond-shaped refractive grating and irradiated to the sub-pixels A arranged in the vertical direction.
In FIG. 11, a plurality of convex reflection surfaces that reflect light from the light source A provided on the right side are provided in a valley portion between two triangular prismatic convex reflection surfaces. Since the light from the light sources B and C provided on the upper side and the lower side in FIG. 11 does not enter the convex reflection surface 5A in the shaded valley of the triangular prismatic convex reflection surface, only the light from the light source A is applied to the subpixel A.
FIG. 12 shows a cross section AA ′ along the valley. The light reflected by expanding the light flux on the convex reflecting surface 5A of FIG. 12 is incident only on the refractive surface 15A of the triangular pyramid lattice and is incident on the sub-pixel 27A. The convex reflection surface 5C shown on the convex reflection surface 5A is not present on the same cross section but is present in the direction perpendicular to the paper surface, but is shown through. The light from the light sources B and C provided on the upper side and the lower side of FIG. 11 is reflected by spreading the light beam on the convex reflection surface 5C and the convex reflection surface 5B existing on the back side thereof, and the refraction surface 15C of the triangular pyramid lattice, respectively. It enters 15B and enters the sub-pixels 27C and 27B. Although the convex reflection surface 5B, the refractive surface 15B, and the sub-pixel 27B are not shown in the figure, the bottom surface of the light guide plate of the convex reflection surface facing the three directions completely transmits the parallel light from the three directions in the direction of the triangular pyramid refraction grating. reflect.

When the convex reflection surface A is formed in a cylindrical shape, when light from the right side is reflected, the upper part of the triangular prismatic convex reflection surface becomes a blind spot and is not illuminated. Therefore, the convex reflection surface A is curved in the long axis direction, and the long axis The direction radiation angle ε is controlled to irradiate the upper pixel of the triangular prismatic convex reflection surface. The radius of curvature R in the major axis direction of the convex reflecting surface is expressed by Equation 5, where L is the length of the convex reflecting surface in the major axis direction.

The range longer than the length in the major axis direction of the convex reflection surface in the direction perpendicular to the triangular prismatic convex reflection surface is irradiated, so that the pixels above the triangular prismatic convex reflection surface can be irradiated.

Light in the three directions reflected by the convex reflecting surface on the bottom surface of FIG. 11 is incident on the A, B, and C surfaces of the triangular pyramid refraction grating provided on the upper surface of the light guide plate. Since the triangular pyramid refraction grating has a structure in which three rhombus surfaces are combined, a liquid crystal panel having rhombic sub-pixels is disposed above the light guide plate. FIG. 13 is a plan view of a liquid crystal display device including hexagonal pixels in which three color sub-pixels are formed in rhombuses and delta-arranged. In FIG. 13, for the convenience of explanation, the dimensions of the sub-pixels are greatly enlarged.
The three color light sources A, B, and C are arranged at the periphery and irradiate from directions different by 120 °. Arrangement of R, G, and B is arbitrary, but since the number of light sources A arranged on the right side is the smallest, it is a good idea to arrange high-luminance elements. The parallel light source A that irradiates in the left direction is arranged on the right side, the parallel light source B that irradiates in the lower right direction of the figure is arranged on the upper side and the upper left side of FIG. 13, and the lower side and the lower left side irradiate in the upper right direction of the figure. The parallel light sources C are arranged. Color display can be performed by mixing light in three directions with hexagonal pixels.

Since the three-color light is irradiated to the sub-pixels through the triangular pyramid refraction grating, the color display of the liquid crystal display device can be performed without using a color filter. Since the convex reflection surface and the triangular pyramid refraction grating are light guide plates made of the same member, Color display can be performed by aligning with pixels. Because it is a hexagonal pixel in which rhomboid subpixels are arranged point-symmetrically, it is excellent in side-by-side additive color mixing and is smoother than square pixels with stripes.
Since the color filter absorbs colors other than the color, the transmittance is 33% or less, and the efficiency of the entire liquid crystal display device is 8% or less if the absorption of the polarizing plate is included. However, since the present invention does not use the color filter, the efficiency is 3 The number of RGB light emitting diodes is about 1/3 that of white light emitting diodes. For this reason, not only the manufacturing process of the color filter can be reduced, but also the cost of the light emitting diode and the power supply unit can be reduced.

In a display device, reproduction is possible with a mixture of the three primary colors, but in an illumination device, an imaging device, etc., accurate color reproduction cannot be achieved if the wavelength characteristics of the light source are lacking. 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 spectrum and a gentle yellow light spectrum, and has a large dip in the blue-green region. 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. For this reason, if the phosphors are not mixed, but are mixed by a triangular pyramid refraction grating or a triangular pyramid reflection grating, the wavelength characteristics are widened without reducing efficiency.

When the first light-emitting element is a blue-violet light emitting diode and the phosphor is dispersed with a two-peak characteristic in which the peak value due to the yellow phosphor is about half of the peak value of the blue-violet light, it has a dip from blue to green, and the red region has decreased. 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 with a double peak characteristic in which the peak value of the orange phosphor is about half of the blue-green light peak value, It is a characteristic with a dip in yellow.
The third light-emitting element is a green light-emitting diode that emits light at the dip wavelength of the first light-emitting element. When the phosphor is dispersed with a two-peak characteristic in which the peak value of the orange phosphor is about half of the peak value of the green light, the color changes from yellow to orange. A characteristic with a dip.
When the first to third light emitting diode lights are additively mixed using the triangular pyramid refraction grating, the dip region of the first light emitting diode is complemented with the excitation light of the second and third light emitting diodes. The fluorescence spectra of the first to third light emitting diodes are approximately equal to the excitation light in the yellow to red region by additive color mixing, and a gentle continuous spectrum of fluorescence can be obtained. Although the efficiency of the method for obtaining broadband characteristics with a phosphor is reduced, continuous wavelengths can be realized with high efficiency by providing another excitation wavelength in the dip region and performing color mixing with a triangular pyramid refraction grating. A perspective view of the main part is shown in FIG. 14, and a cross-sectional view is shown in FIG. FIG. 22 shows wavelength characteristics before and after synthesis in which fluorescence conversion light emitting diodes having different excitation wavelengths are mixed with a triangular pyramid color mixing device.

Since the illumination device is often used with a wider radiation angle than the parallel light, it is possible to widen the radiation angle of the mixed parallel light with respect to the parallel light by the negative focal length optical system. If the radiation direction is different, only one component is obtained. Therefore, each light source light can be irradiated with uniform color mixing light by aligning the radiation angle and direction. In FIG. 16, a concave lens array is provided at the exit of the refractive grating.

The radiation angle can be expanded by making the inclined surface of the refractive grating concave, as shown in FIG. Uniform color mixing light can be emitted by aligning the emission angles of the emitted light of the concave surfaces of the opposing refractive grating inclined surfaces. In order not to be incident on the opposing refractive grating inclined surface, it is necessary to enter with a tangential inclination at the refractive grating valley. For this reason, since it does not inject into the top part of a refractive grating, it is not necessary to sharpen a top part, and it can also make it easy to shape | mold by flattening.

It is also possible to increase the radiation angle after passing through the focal point by making the inclined surface of the refractive grating convex. Even if the inclined surface of the refractive grating is flat, when the incident light is not parallel light but diffused light, it is diffused light after exiting the refractive grating. By making the reference surface of the refractive grating not a flat surface but a concave surface, diffused light can be incident on the refractive grating and emitted.
If the light source part is diffused light from one point, the angle of incidence on the reference surface of the refractive grating varies depending on the position, but if it is diffused light from a plurality of points, the angle of incidence on the reference surface can be made uniform.
In the case of spotlights, traffic lights, etc., the radiation angle θ of the irradiation range or the observable range is easier to use than the width W on the display surface of FIG. When expressed by the curved surface length d and the radiation angle θ, it is expressed by Equation 6 and can be approximated by Equation 7. Here, the radiation angle is symmetric with respect to the center line as shown in FIG.

FIG. 10 shows a state in which parallel light from two directions is mixed and emitted in the same direction at a radiation angle θ. If the radiation angle is the same and the direction is the same and the grid cannot be recognized, additive color mixing is performed evenly.

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. Six colors or nine colors can be mixed by using mixed light from the refractive grating or the reflection grating for the three light sources incident on the triangular pyramid refractive grating. Since it is not a color mixture due to scattering, it is possible to irradiate white light with a narrow emission angle. When the six colors are mixed, white light having a continuous spectrum can be synthesized as shown in FIG.
An example of a perspective view of the main part of this structure is shown in FIG. 18, and examples of cross-sectional views are shown in FIGS.

Since the refraction grating on the exit surface can enter a plurality of lights on one grating inclined surface, the number of refraction gratings in FIG. 20 is half that in FIG. FIG. 21 uses the light beam expansion function of the convex reflection grating on the bottom surface of the light guide plate and eliminates the concave refractive surface of the light guide plate exit surface of FIG.

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.
With a structure in which a triangular pyramid refraction grating and a convex reflecting surface grating are oriented in three directions, a three-color stripe can be realized with a single light guide plate, which eliminates the need for alignment, improves productivity, and reduces material costs. I can do it.
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, multiple excitation lights can be used, and a continuous spectrum can be realized with high efficiency. I can do it.
Continuous spectrum white light can be obtained with higher efficiency than the method of broadening the spectrum by mixing phosphors in a multi-component system.

Cross section of triangular wave reflection grating Plan view of a structure combining a convex triangular pyramid reflection grating and a concave triangular pyramid reflection grating Principle of color mixing with triangular wave refraction grating Perspective view showing the principle of color mixing with a triangular pyramid refraction grating Plan view of a structure combining a convex triangular pyramidal refractive grating and a concave triangular pyramidal refractive grating Principle diagram of light flux expansion by convex reflecting surface Color mixing and radiation angle by a pair of convex reflection gratings Diffuse light incident / exit angle Cross-sectional view of a light guide plate of a liquid crystal display device using both a reflection grating and a triangular pyramid refraction grating Sectional drawing of the light-guide plate of the liquid crystal display device which irradiates several triangular pyramid refraction grating | lattice from one convex reflection grating A plan view in which three types of convex reflection gratings are arranged on the bottom surface of the light guide plate and three types of light sources are arranged on the side surface of the light guide plate. Cross-sectional view of a light guide plate of a liquid crystal display device using both a reflection grating and a triangular pyramid refraction grating Plan view of a liquid crystal display device comprising rhomboid sub-pixels Perspective view of the main part of the lamp by mixing three types of fluorescent conversion light emitting diodes and triangular pyramid refraction grating Cross-sectional view of the lamp by mixing three types of fluorescent light-emitting diodes and a triangular pyramid refraction grating Cross-sectional view of diffusing outgoing light from triangular pyramid refraction grating with concave lens Cross-sectional view of diffusing outgoing light by concave refractive surface of triangular pyramid refraction grating Perspective view of the main part of the lamp with mixed colors of six types of light emitting diodes and triangular pyramid refraction grating Cross-sectional view of a lamp with a mixture of six types of light emitting diodes and triangular pyramid refraction grating Color mixing when the triangular pyramid refraction grating on the output side is twice the size of the two-color refraction grating Color mixing when the output side triangular pyramid refraction grating and the two-color refraction grating are the same size Synthetic spectrum by mixing three types of fluorescent white light emitting diodes Synthetic spectrum by mixing 6 types of light emitting diodes Cross section of an example of a traffic light Plan view of an embodiment of a traffic light Schematic diagram showing only forward scattered light in a conventional color mixing device with a conical scattering surface Conventional package that mixes colors by relieving color spots by making the reflector near the chip steeply inclined Conventional example without a color filter that totally reflects in the direction of the liquid crystal panel at the interface of the 45 ° groove 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 Conventional example of three-color liquid crystal display device using terraced convex light guide plate and stripe distribution element Conventional example in which light in two directions is incident on a right-angle prism and mixed with a band-pass mirror

Example 1
A liquid crystal display device composed of rhomboid sub-pixels by using a triangular pyramid refraction grating will be described. FIG. 11 is a plan view in which three types of convex reflection gratings are arranged on the bottom surface of the light guide plate of the liquid crystal display device, and three types of light sources are arranged on the side surface of the light guide plate, and FIG. 11 is a plan view of the liquid crystal display device having rhomboid subpixels. It is shown in FIG. When the diagonal size is 1117 mm (46 type) and full HD (1920 × 1080), the screen size is 1018 mm wide, 573 mm long, pixel pitch is 530 μm, and the rhombus side length of the subpixel is 306 μm.
The bottom surface of the light guide plate has three types of convex reflecting surfaces facing three directions. The parallel light B irradiated in the lower right direction of the figure is reflected obliquely upward by the cylindrical convex reflection surface B and is incident on the rhomboid refractive grating B at an incident angle α. The parallel light C radiated in the upper right direction of the figure is reflected obliquely upward by the cylindrical convex reflection surface C that forms a ridge in contact with the cylindrical convex reflection surface B, and is incident on the rhomboid refractive grating B at an incident angle α. . The light from the parallel light source A in the leftward direction is reflected obliquely upward by the cylindrical convex reflection surface A and is incident on the rhomboid refraction grating at an incident angle α.
The subpixels A, B, and C are irradiated with the direction changed in the vertical direction by the refractive surfaces A, B, and C of the triangular pyramid refraction grating.
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 540 light emitting diodes having a luminous intensity of 240 mcd for the light source A and arranging 540 light emitting diodes having a luminous intensity of 140 mcd for the light sources B and C, a luminance of 263 cd / m ² can be obtained when the light transmittance is 40%. The power consumption at this time is about 130 W, which is about 1/3 that of the white light emitting diode and the color filter.
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
An embodiment of an illumination device using a triangular pyramid refraction grating and using three types of fluorescent conversion light emitting diodes in three directions will be described with reference to FIGS. The first fluorescence conversion light emitting diode A has an excitation wavelength of 440 nm and a fluorescence wavelength of 550 nm. The second fluorescence conversion light emitting diode B has an excitation wavelength of 475 nm and a fluorescence wavelength of 590 nm. The third fluorescence conversion light emitting diode C has an excitation wavelength of 510 nm and a fluorescence wavelength of 590 nm. FIG. 15 is a sectional view between the first fluorescence conversion light emitting diode A and the second fluorescence conversion light emitting diode B, and therefore the third fluorescence conversion light emitting diode C is not shown.
Each of the light emitting elements 1A and 1B is provided at the focal point of the off-axis paraboloidal mirror 6 and six in the depth direction of the paper. The light is converted into parallel light by the off-axis paraboloidal mirror 6, is reflected by the reflecting surface 47 that is dispersed and disposed on the light guide plate 24, and enters the triangular pyramid refraction grating 15.
In order to make the radiation angle about ± 10 °, the exit surface of the triangular pyramid refraction grating is a concave refracting surface.
When a forward current of 100 mA is passed through each light emitting element, the total light source becomes 6.3 W with 18 light sources, and a luminous flux of 500 lm can be obtained with a conversion efficiency of 80 lm / W 2. The mixed spectrum is white light having a continuous spectrum as shown in FIG. Since the visible light range is close to white light of 5500K, high color reproducibility is required, and it is suitable for applications that do not include infrared rays, avoid temperature rise, and avoid damage caused by ultraviolet rays.

Example 3
An embodiment of an LED bulb using a triangular pyramid refraction grating and using six-color light emitting diodes in three directions will be described. FIG. 18 is a perspective view of the main part seen through. The light sources in the three directions for irradiating the triangular pyramid refraction grating are the light guide plate having the convex reflection surface facing in both directions and the bidirectional light source described in FIG. FIG. 20 shows a cross-sectional view of a light guide plate having a triangular pyramid refraction grating and a convex reflection surface facing in both directions. A light guide plate having a convex reflection surface facing in both directions reflects and reflects parallel light from two directions by expanding the light beam, returns it to parallel light at the convex refractive surface of the light guide plate exit surface, and then enters the triangular pyramid refraction grating. . Since the outgoing light of the triangular pyramid refraction grating is parallel light, the concave refracting surface 11 is provided to spread the light flux to a necessary radiation angle. When the radiation angle is narrow, the triangular pyramid refraction grating may be constituted by a concave refracting surface as shown in FIG. The mixed spectrum is white light having a continuous spectrum as shown in FIG.

Example 4
A signal device that combines yellow light using a red light emitting diode and a green light emitting diode will be described as an example in which two colors of parallel light are incident on and mixed with a light guide plate having a convex reflection surface in both directions. 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. FIG. 24 is a cross-sectional view of a traffic light that displays green and red parallel light on a grating having a convex reflecting surface in both directions and displays a yellow-orange color by mixing green and red in the case of a yellow signal.
On the bottom surface of the light guide plate, the convex reflection surface facing in both directions shown in FIG. 7 forms a ridge. Since the distance to the traffic light display surface is about 5 m or more, the grating cannot be recognized if the width of the convex reflection surface is 5 mm or less, and when red light and green light are emitted from the convex reflection grating in the same direction at the same radiation angle, additive color mixing The occurrence of color spots does not occur.
A light source unit is provided around the display surface, a green light emitting diode is provided on one side, and a red light emitting diode is provided on the other side at the focal point of each of 96 elliptical mirrors, and then parallel light is formed by a parabolic mirror to form one convex reflecting surface. Is incident. The pair of convex reflecting surfaces reflect in the same direction at the same radiation angle, and the luminous flux is expanded to the required radiation angle on the concave refractive surface of the light guide plate surface. The directivity to irradiate the conventional sky and 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 about 1/4. Can be reduced. 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.
When a blue-green light emitting diode of 500 nm or less is used and mixed with a red light emitting diode, the straight line on the chromaticity coordinate approaches a white region and becomes pale yellow. Therefore, when a green light emitting diode of 500 nm or more and a red light emitting diode of 610 nm or more are used. Since the mixed color line is along the right edge of the chromaticity coordinates in the shape of a horseshoe, dark yellow can be mixed.
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. 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. 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, since the convex reflection grating is displayed with a width that cannot be recognized, 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.

1: Light emitting element 4: Triangular wave reflection grating 5: Convex reflection surface
6: Parabolic mirror 8: Elliptical mirror 9: Hyperbolic mirror
10: Convex refracting surface 11: Concave refracting surface 15: Refraction grating 16: Excitation light 17: Fluorescence 18: Translucent material
19: Parallel light 20: Diffuse light 21: Concave mirror
22: Convex mirror 24: Light guide plate 27: Sub-pixel
28: Liquid crystal sandwich substrate 29: Substrate 30: Circuit board
31: Tanibe 32: Top 33: Ellipse
34: Air layer 37: Incident surface 38: Support member
39: scattering surface 40: focal point 42: groove
43: Square pyramid 45: Incident light 46: Light source
47: Band pass mirror 48: Polarizing plate 49: Prism 50: Reference plane 51: Blind spot

Claims (8)

One diagonal line of the rhomboid refracting surface is provided on the reference plane, and adjacent sides of the rhomboid refracting surface above the diagonal line on the reference plane are arranged in contact with each other to form a convex triangular pyramid refraction grating above the reference plane ,
Forming a concave triangular pyramid refraction grating recessed from the reference surface by arranging adjacent sides of the rhomboid refractive surface below the diagonal line in contact with each other,
As the structure in which the angle of inclination that the rhomboid refracting surface makes the normal to the reference surface is set by the difference between the incident angle and the refraction angle, the light is emitted from the high refractive index side to the low refractive index side.
The parallel light from the light sources in the three directions propagates substantially parallel to the non- opposing refracting surfaces and enters only the refracting surfaces facing the triangular pyramid refracting surface .
An illuminating device characterized by being refracted vertically above a reference surface and mixing by making the emission directions coincide. The triangular pyramid refraction grating according to claim 1 is formed on the exit surface of the light guide plate, and further a convex reflection surface is formed on the bottom surface of the light guide plate,
It consists of a structure in which parallel light inclined from the side surface of the light guide plate to the bottom surface is incident on the convex reflection surface,
An illumination device characterized in that a light beam is magnified by a convex reflecting surface, reflected by a triangular pyramid refraction grating, irradiated onto a sub-pixel, and irradiated with parallel light of three colors from three directions onto a pixel composed of a rhomboid sub-pixel. . The cylindrical convex reflection surface on the bottom of the light guide plate is smaller in number of pixels than the number of pixels, and molding is performed by expanding the size of the convex reflection surface by irradiating a plurality of subpixel columns from one cylindrical convex reflection surface. The lighting device according to claim 2, wherein the lighting device is made easy. Formed on the bottom surface of the light guide plate in the shape of a triangular prism in contact with the top ridge of the cylindrical convex reflection surface parallel to the two opposite sides of the light guide plate side surface,
Between the two triangular prismatic convex reflective surfaces, a plurality of convex reflective surfaces are provided in a direction orthogonal to the triangular prismatic convex reflective surface,
Irradiate a triangular prism-shaped cylindrical convex reflection surface from two color light sources provided on two opposite sides of the light guide plate side surface,
Consisting of a structure in which a light source provided in a direction perpendicular to the triangular prismatic convex reflecting surface irradiates the convex reflecting surface in a direction perpendicular to the triangular prismatic convex reflecting surface, parallel light from three directions is opposed to the triangular pyramid refraction grating. The illumination device according to claim 2, wherein the illumination device is incident on three sub-pixels. A curved surface is formed in the major axis direction of the convex reflection surface in the direction orthogonal to the triangular prismatic convex reflection surface,
3. The illumination according to claim 2, wherein the upper pixel of the triangular prismatic convex reflecting surface is irradiated by irradiating a range longer than the length in the major axis direction of the convex reflecting surface in a direction orthogonal to the triangular prismatic convex reflecting surface. apparatus. The above triangular pyramid refraction grating, a liquid crystal panel comprising a hexagonal pixel by sub-pixel of the three rhombic arranged, refracted diamond by sub three directions of the light reflected by the convex reflecting surface is triangular pyramid refraction grating It consists of a structure that irradiates pixels,
3. The illumination device according to claim 2, wherein color display is performed by mixing light in three directions with hexagonal pixels. The inclined surface of the triangular pyramid refraction grating is composed of the concave surface of the tangential inclination in the refractive grating valley,
2. The illumination device according to claim 1, wherein a radiation angle of light emitted from the refractive grating is expanded. Reflecting parallel light from two directions on a convex reflecting surface having a curvature radius r and a curved surface length d along the circumference,
3. The illumination device according to claim 2, wherein the radiating device emits mixed colors in the same direction at a radiation angle θ = d · 360 ° / (2πr).