JP4681059B2 - Fluorescent light-emitting diode - Google Patents

Description

  The present invention improves the efficiency by reflecting the light emitted from the phosphor layer of the semiconductor light emitting element using the phosphor to the light emitting element side by a reflecting mirror to improve the efficiency. The present invention relates to a light-emitting element that prevents light emission and a lighting device using the light-emitting element.

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. The proposal (FIG. 17, Patent Document 1) in which three color light-emitting elements are provided on the inner surface of the cone to increase the color mixing distance by backscattering increases absorption due to multiple reflections and decreases efficiency. 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 steepening the inclination of the reflecting mirror near the light emitting element (FIG. 18, 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 spectrum of a fluorescent white light-emitting diode with a complementary color obtained by irradiating the blue light of a blue light-emitting diode to a yellow phosphor such as an yttrium / aluminum oxide phosphor is composed of two peaks in a sharp blue and gentle yellow region (patent) Reference 3). It has a strong bluish spectral characteristic with very little red range and a large dip in green. However, fluorescent white light-emitting diodes are often used as backlights for liquid crystal display devices such as mobile phones because they have a simpler structure than mixed colors 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).

  The phosphor of the fluorescent white light-emitting diode is dispersed in a translucent resin and dispersed inside the cup-shaped concave mirror or the entire mold of the surface mount component. However, blue light increases in the optical axis direction and yellow light in the tilt angle direction. As a result, the cup-shaped concave mirror is divided into two steps to divide the phosphor-dispersed resin into a uniform thickness and a lower recess to make the sealing member uniform in shape. Patent Document 4) and a proposal (Patent Document 5) that uses an injection molding machine to prevent particle sedimentation in order to improve the uniformity of the dispersed state.

Since illumination recognizes color by reflected light from the light source, the spectral characteristics of the light source affect the color rendering, and if the wavelength is missing, information is lost and accurate color reproduction cannot be achieved. A three-wavelength cold cathode tube close to a line light source is often used as an imaging light source. However, since the fluorescent materials of each color have a line spectrum, the wavelength characteristics have large irregularities, and the cold cathode tube requires an inverter. A proposal of a scanner light source in which a light emitting diode is arranged at a focal point formed in a linear shape of an elliptical cylindrical reflector and the reading surface is the other focal line is shown as a light emitting diode of three primary colors (Patent Document 6). In order to obtain a continuous spectrum, more multi-colored elements are required, and the wavelength width at which the luminous intensity of the light emitting diode is about half the peak is 20 nm to 60 nm, so a proposal to cover the visible light range 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 Japanese Patent No. 3604298 Japanese Patent No. 3541709 JP-A-8-307610 Japanese Patent No. 4114173

A conventional fluorescent white light-emitting diode in which a light-emitting element is provided at the bottom of the cup-shaped concave mirror and phosphors are dispersed inside uses fluorescence emitted forward from the phosphor, but the direction of light emission from the phosphor is the forward emission direction Besides, there is a direction returning to the light emitting element and a direction emitting to the cup-shaped concave mirror. The light returning to the light emitting element is incident on the inside of the light emitting element due to refraction, or reflected in the emission direction or the concave mirror direction depending on the incident angle. Absorption occurs when refracting and reflecting multiple times. A part of the fluorescence emitted forward hits another phosphor and is absorbed, but when it returns to the light emitting element direction, the phosphor particles hit and absorb. When the fluorescence-converted wavelength hits the phosphor again, the excitation wavelength characteristic does not reach the fluorescence region, so that it is reflected and absorbed, and absorption is further increased by repeating reflection between the light emitting element and the phosphor.

The phosphor of the fluorescent white light-emitting diode is dispersed in a translucent resin and dispersed in the inside of the cup-shaped concave mirror or the entire mold of the surface mount component. The phosphor is also dispersed in the vicinity of the light emitting element, and the luminous flux density increases in inverse proportion to the square of the distance in the vicinity of the light emitting element. The heat dissipation structure is important because the heat generated in the light-emitting element conducts heat to the phosphor and promotes deterioration according to the Arrhenius law. However, the phosphor dispersed in the vicinity of the light-emitting element is also promoted by heat. .

Many proposals have been made to uniformly disperse the blue to greatly change the blending ratio and blending unevenness of the phosphors and to produce color spots due to directivity. In order to improve the amount of blue light on the optical axis and the amount of yellow light in the ambient light, there has been a proposal to uniformly disperse phosphors to make the thickness uniform. However, even if the phosphor is uniformly dispersed to make the thickness of the phosphor layer uniform, the optical path length of the phosphor layer on the optical axis and the peripheral part of the light emitting element is longer in the peripheral part than in the vicinity of the optical axis. The ratio between the phosphor layer thickness t on the optical axis and the optical path length r to the periphery is expressed by Equation 1.

When θ is 30 °, it becomes 15.5% longer in the peripheral direction. Therefore, even if the thickness is uniform, yellow fluorescence increases in the ambient light, and color spots are generated.

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. When the fluorescent light is transmitted without passing through the fluorescent material in the traveling direction, yellow light is emitted. When the fluorescent material hits another yellow fluorescent material, the fluorescent material is colored and opaque and is absorbed because the fluorescence conversion rate is low with respect to the fluorescent 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 luminous efficiency and conversion efficiency, and light emitted from long-wavelength phosphors is absorbed only by short-wavelength phosphors and is not converted to fluorescence. Occurs. 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.

The proposal to mix colors by arranging the light emitting elements in the same package and steeply tilting the reflecting mirror near the light emitting elements is different in distance and angle from each light emitting element to the reflecting mirror. Produce. Since color mixing by regular reflection is difficult, there is a problem that reflected light returns to the light source side due to color mixing such as long scattering distance by using a scattering layer, and the efficiency is reduced due to absorption in multiple reflection. is there. Since there is no efficient color mixing means outside, the fluorescent white light-emitting diode results in a method of mixing phosphors and mixing colors.

An opening 23 for transmitting the excitation light 16 from the light emitting element 1 is provided in the fluorescent reflecting concave mirror 3 having the phosphor dispersion film 7 as a focal point, and a light emitting element surrounding concave mirror 2 is provided as an opening crossing the transmission opening, It has a structure in which a light emitting element is provided. The phosphor dispersion film is irradiated with excitation light from the light emitting element through the opening, and the converted fluorescence 16 is reflected by a fluorescent reflecting concave mirror having the phosphor dispersion film as a focal point and emitted. A concave mirror having a large focal length with the phosphor dispersion film as a focal point is called a fluorescent reflecting concave mirror, and a concave mirror around the light emitting element is called a light emitting element surrounding concave mirror. FIG. 1 shows a structure in which the concave mirror around the light emitting element is formed of an elliptical mirror and the radius of the phosphor dispersion film is set to the size of the light emitting element chip to realize a narrow emission angle. When the excitation light passing through the elliptical mirror from the light emitting element is condensed on the phosphor in focus, the phosphor emits light in all directions. Fluorescence emitted from the phosphor in the half space on the light emitting element side has a smaller opening area of the concave mirror around the light emitting element than the fluorescent reflecting concave mirror, so most of the fluorescence emitted from the rear side of the phosphor irradiates the fluorescent reflecting concave mirror. Is done. Fluorescence emitted in front of the phosphor is converted into parallel light by providing a lens having the phosphor as a focal point, and emitted forward. If the fluorescent reflecting concave mirror is a parabolic mirror or a parabolic approximate curvature spherical mirror, the fluorescent light can be emitted as parallel light in the same manner as the parallel light from the front lens.

When light is emitted from the focal point of the ellipsoidal mirror and condensed on the other focal point, the light emitting element has a finite dimension of about 250 μm on each side, and therefore the light is condensed to the same extent as the dimension of the light emitting element. The reflected light from the elliptical mirror is focused on the phosphor, but the direct light from the light emitting element is diffused light, so if the phosphor dispersion film diameter is small, it will be displaced around the focal point and will not be converted to fluorescence. The deviated excitation light is reflected on the phosphor dispersion film . When the phosphor dispersion density is increased compared to the conventional white light emitting diode in which the phosphor is dispersed inside the cup-shaped reflector, and the phosphor volume is concentrated in a lump with a phosphor volume equivalent to that of the light emitting element, it is transmitted forward. A circular film in which a phosphor is dispersed in a transparent resin is suitable because it becomes difficult. A film in which a phosphor is dispersed in a transparent resin is referred to as a phosphor dispersion film or a phosphor film. When the irradiation area is enlarged by using a phosphor dispersion film, it is possible to reduce the escape of excitation light. In the case of a phosphor dispersion film having a large diameter, not only an elliptical mirror but also a conical mirror, a cylindrical mirror, and a pyramid mirror can be used depending on the shape of the illumination device.

When a phosphor volume of 0.0156 mm ³ having the same amount as the light emitting element volume is formed into a circular phosphor dispersion film having a radius of 0.6 mm, the thickness becomes 14 μm. When fluorescent conversion is used and only fluorescent light is used, the fluorescent material having an average particle diameter of 10 μm is arranged in a staggered manner in a cross-sectional view, and the filling rate is high. Can radiate forward. If the phosphor dispersion film thickness is increased, the fluorescence will not be transmitted forward but will be absorbed by the front phosphor, so the volume balance of the phosphor will be controlled without dense packing, and the spectral balance of excitation light and fluorescence will be adjusted . I can take it .

When balancing the spectrum of excitation light and fluorescence, the phosphor film emits light not only in the front direction but also in the direction of the fluorescence reflecting concave mirror, so the white particles 13 are mixed in addition to the phosphor particles 12 to reflect the excitation light, It is necessary to roughly match the forward excitation light transmittance. When the phosphor and white particles are mixed with a transparent resin to form a film, the transmittance can be set by the volume filling rate of the phosphor and the white particles. By mixing transparent particles corresponding to the product of the volume of white particles and the reflectance and applying the mixture to the entire surface, the transmittance and reflectance of the excitation light can be made equal. The transmission part is treated as transparent particles, and FIG. 2 shows a schematic diagram in which phosphor particles, white particles, and transparent particle mixtures are arranged in a single layer staggered pattern.

In FIG. 2, a phosphor film composed of a phosphor / white particle mixture and a transmission part is schematically represented by all eight particles, and half of the phosphors, four white particles, and two transparent particles are shown. For white particles, highly reflective substances such as magnesium oxide (reflectance: 0.98), silica, titanium oxide, etc. are suitable. When the reflectance is approximated by 1 and the transmittance of the transmission part or transparent particle is approximated by 1, the forward direction is increased. The transmitted light amount of the excitation light can be made equal to the reflected light amount of the excitation light toward the fluorescent mirror. As the fluorescence conversion efficiency α of the phosphor that has received the excitation light I, the same amount of fluorescence is emitted in the front and rear spaces, and since the number of phosphors is half, the amount of fluorescence is I · α / 4 for both the front and rear.

The concave mirror around the light emitting element is suitable to have an elongated shape for efficiently irradiating the phosphor. In the case of an elliptical mirror, the ratio of a / b is large when the major axis diameter of the elliptical mirror in Equation 2 is a and the minor axis diameter is b. As shown in FIG.

When the focal point of the fluorescent reflecting concave mirror is shifted to the front side of the phosphor side focal point of the elliptical mirror, the light condensed on the fluorescent side focal point of the elliptical mirror is around the focal point of the fluorescent reflecting concave mirror. It penetrates inside. If the phosphor film is formed with this circular dimension, the diameter of the phosphor film is larger than that of the phosphor film near the focal point in FIG. A reflecting mirror is provided for converting the light emitting component from the phosphor film to the plane direction of the phosphor film and obliquely forward while converting the component to the fluorescence reflecting mirror direction.
A structure in which the concave mirror around the light emitting element is an elliptical mirror and a diaphragm is provided at the focal point to irradiate the phosphor with the diffused light after passing through the focal point is also possible. However, it is necessary to condense the light directly onto the diaphragm to prevent a reduction in efficiency.

FIG. 4 shows a state where the light is emitted from the phosphor at the focal point of the parabolic mirror and converted into parallel light. However, the focal point and the outer peripheral portion incident on the point of the fluorescent reflecting concave mirror as the diameter of the phosphor circular film increases. The deviation becomes large and the reflected light of the fluorescent reflecting concave mirror has a diffused light component. When the light from the phosphor film is converted into parallel light, the error angle θ from the parallel light at the outer periphery of the phosphor film is the radius r of the phosphor film, the coordinates (x, y) of the parabolic mirror, the fluorescence This is shown in FIG. 6 and Equation 3 by the focal length p of the reflective parabolic mirror.

As shown in FIGS. 4 and 6, the error from the parallel light due to the diameter of the phosphor film becomes wider as it gets closer to the top of the fluorescent mirror, and becomes narrower in the periphery. For this reason, the phosphor film with a small diameter as shown in FIG. 1 is suitable for applications with a narrow emission angle, and the phosphor film with a diameter larger than the opening diameter of the concave mirror around the light emitting element as shown in FIG. 2 is suitable for applications with a wide emission angle. ing.

If the aperture diameter of the concave mirror around the light emitting element is reduced, the ratio of the amount of light returning from the phosphor film to the concave mirror aperture around the light emitting element can be reduced. The ratio of the amount of light returning to the concave mirror opening around the light emitting element is the ratio of the elliptical mirror opening area to the total spherical area with radius r from the phosphor to the opening as shown in FIG. The ratio of radiation to the concave mirror opening around the light emitting element with respect to the total amount of radiated light is an angle α formed by a line connecting the optical axis and the boundary between the optical axis and the optical axis. It can be expressed by the ratio.

When the radius of the fluorescent reflecting concave mirror is 5 mm and the opening radius of the concave mirror around the light emitting element is 1 mm,
Since α = 11.5 ° and S / T = 0.01, the amount of light returning to the concave mirror around the light emitting element is negligible.

The fluorescent reflecting concave mirror can select the phosphor area and concave mirror curve according to the target radiation angle, and can be adopted according to the purpose, such as a spherical mirror that is easy to manufacture and a hyperbolic mirror that forms diffuse light. 4 and 10 show a parabolic mirror having an open optical axis, which reflects parallel light in the outer peripheral direction, changes the direction on the refracting surface, and emits the light from the entire diameter. FIG. 8 shows an example in which the light is reduced in thickness by converting light toward the focal point into parallel light on the concave refractive surface using an elliptical mirror. The convex mirror in front of the phosphor in FIG. 8 has an effect of compensating the low light flux density in the peripheral part of the parabolic mirror by reflecting the forward diffused light to the rear fluorescent reflecting concave mirror. FIG. 9 is an exploded perspective view showing the surface-mounted component having the configuration shown in FIG. FIG. 10 shows an example in which a rotating paraboloid mirror is provided on one lead of a bullet-type light emitting diode, a concave mirror around the light emitting element is provided on the other lead, and the reflecting mirror is divided to shorten the bonding wire.

Since the fluorescence emitted forward from the phosphor film is diffused light, a state in which a convex lens is provided to narrow the radiation angle so as to match the emitted light of the fluorescent reflecting concave mirror is shown in FIGS. A reflecting mirror as well as a convex lens can be used, and FIG. 11 shows a state in which fluorescence diffused forward from the phosphor film is converted into parallel light by a parabolic mirror. In order to emit light in the vertical direction, the direction is changed by a plane mirror. The structure shown in FIG. 11 can be thinned because the concave mirror around the light emitting element faces sideways.

To form a phosphor film, a method of applying a binder to a phosphor film and applying it to a transparent film, a method of spraying phosphor particles on a transparent film to which a binder is attached, a film formation after kneading phosphor and resin A phosphor film can be formed by a method or the like. When the excitation light is ultraviolet light, if there is an unfilled portion, the ultraviolet light is transmitted, so that it is necessary to densely fill the phosphor particles. If the excitation light is transmitted and used, a transparent part is provided to set the transmittance. However, if the phosphor, white particles, and transparent particle mixture is attached to a transparent film coated with a binder, it is easier than controlling the coverage. It is.
The phosphor / white particle / transparent particle mixture film is cut into a predetermined shape, placed at the focal point of the fluorescent reflector, and further covered with a resin, so that the protective function can be achieved simultaneously with the formation of the optical system.
In the process of resin molding up to the vicinity of the elliptical mirror focal point of the light emitting diode, if a dispersion mixed with phosphor particles, white particles, and translucent particles in an appropriate ratio is attached to the mold surface, then resin molding is performed. The step of forming the phosphor film in advance can be omitted.
To provide a reflecting mirror for converting the light emitting component from the phosphor film to the plane direction and obliquely forward of the phosphor film into the direction of the fluorescent reflector, a mixture of phosphor particles, white particles, and transparent particles on a film coated with the reflecting film Or a manufacturing method in which a reflective film is provided in a later step.

In conventional phosphor particle dispersions, multiple reflections are absorbed by other phosphors present in the space, but in the case of phosphor films, there is no spatial multiple reflection / absorption, so the fluorescence conversion efficiency of multiple types of phosphors The spectrum of white light or multicolor light can be designed and realized with the component ratio corrected in (1).
Since the fluorescence spectrum converted from the excitation light depends on the surface area ratio of the phosphor and the conversion efficiency, it is possible to solve the radiation angle dependency of the color derived from the length of transmission through the phosphor dispersion layer.

A lighting device uses multiple light emitting elements to obtain a large luminous flux. However, if a multi-component phosphor is covered with a single excitation light and covers the visible light band, all the fluorescence conversion efficiency is applied, and the fluorescence strikes other phosphors. Decreases. For this reason, when using a some light emitting element, it is more efficient to employ | adopt multiple excitation light and to mix colors outside. The light emitting element of the light source section is not limited to a single element, but it is possible to realize a broadband characteristic including a plurality of excitation lights by configuring a plurality of phosphors having a wide excitation wavelength characteristic, but if a plurality of elements are provided in the light source section, the light emitting element Since the aperture of the surrounding concave mirror becomes large and the diffused light component increases, it is suitable for applications with a large radiation angle.

Since it is necessary to dissipate heat because an illuminating device needs to arrange a large number of light emitting elements in order to obtain a large luminous flux, FIGS. The efficiency is improved as compared with a method of realizing a white light spectrum by mixing phosphors with multiple components, and a narrower emission angle can be obtained than when a plurality of elements are provided inside the light source part reflecting mirror. The light source unit shown in FIG. 12 has a structure in which the structure shown in FIG. The light source unit shown in FIG. 13 converts the fluorescent reflecting concave mirror into an elliptical mirror, converts it into parallel light by the front convex reflecting surface, and irradiates the triangular wave reflecting grating. This is a structure in which the structure of converting into parallel light on the concave refracting surface in FIG. 8 is transformed into a convex mirror to change the direction. The front of the phosphor is diffused and reflected by the convex mirror to the rear fluorescent reflecting elliptical mirror.

The fluorescent light emitted from the phosphor to the light emitting element side half-space is irradiated to the fluorescent reflecting concave mirror and reflected and emitted forward, so that the light emitting element that has been absorbed from the phosphor to the light emitting element and its periphery is absorbed. The fluorescence utilization efficiency of the half space on the side is improved.
Since the phosphor film emits light forward and backward, it can be emitted forward to the rear fluorescent reflecting concave mirror without being absorbed by other phosphor particles.
In the case of a phosphor film, since there is no multiple reflection / absorption in space, light is emitted with a spectrum of component ratios corrected by the fluorescence conversion efficiency of a plurality of types of phosphors. For this reason, the radiation angle dependence of the color derived from the length which permeate | transmits a fluorescent substance dispersion layer can be solved.
The phosphor film is provided in front of the concave mirror around the light emitting element, and since the reflected light of the concave mirror and the direct light from the light emitting element are irradiated, it is possible to avoid concentrating on the local area of the phosphor. For this reason, deterioration of the phosphor due to concentration in the vicinity of the light emitting element can be prevented.
Mixing with a multi-component system to achieve a white light spectrum can improve efficiency by mixing colors externally, and in lighting applications where a large number of light emitting elements are arranged, the triangular wave reflection grating that also serves as a heat sink is irradiated and mixed. Depending on the structure, the wavelength for exciting the phosphor can be optimized. A narrower radiation angle can be obtained than when a plurality of elements are provided inside the light source reflection mirror.
By effectively emitting the fluorescence emitted from the phosphor toward the light emitting element by the fluorescent reflecting concave mirror, the number of light emitting elements used in the lighting device is reduced, and the heat dissipation structure is simplified by reducing the loss. For this reason, the manufacturing cost of the lighting device can be reduced.

For the sake of explanation, the main part is enlarged and displayed, so the relation is not necessarily similar.
Sectional view of reflection from the phosphor layer near the focal point of the light emitting element surrounding elliptical mirror to the fluorescent reflecting concave mirror Cross-sectional view of a white light-emitting diode with a phosphor film made of a phosphor / white particle / transparent particle mixture at the focal point of the fluorescent reflecting concave mirror Graph of light emitting element surrounding elliptical mirror and fluorescent reflecting parabolic mirror Sectional view of reflecting from the phosphor film in front of the focus of the elliptical mirror around the light emitting element to the fluorescent reflecting concave mirror Principle diagram of diffuse light component generated by phosphor film dimensions in a fluorescent reflective parabolic mirror Distribution of diffused light component by parabolic mirror according to the size of phosphor film Total space integral of the ratio of the concave mirror opening area around the light emitting element to the radiation angle Cross-sectional view of parallel light emission by combining a fluorescent reflecting ellipsoidal mirror and concave refractive surface Disassembled perspective view showing structure of light emitting element surrounding elliptical mirror, phosphor film, and fluorescent reflecting concave mirror Cannonball type white light-emitting diode with separate concave mirror and fluorescent reflecting concave mirror Cross-sectional view of a surface-mounted component that converts the fluorescence in front of the phosphor into parallel light using a parabolic mirror Sectional view of a color mixing device using two types of fluorescent white light using a triangular wave grating and a lens-shaped light source Sectional view of a color mixing device using two types of fluorescent white light with a triangular wave grating and a reflective light source Cross section of convex grid unit Front view of vehicle headlamp Combined spectrum of two types of pseudo white light emitting elements 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 Conventional fluorescent white light emitting diode dispersing phosphor

Example 1
An embodiment of a surface-mounted component of a white light-emitting diode in which a phosphor film made of a phosphor / white particle / transparent particle mixture is provided at the focal point of a fluorescent reflecting concave mirror will be described. It is the structure shown in sectional drawing of FIG. 2, FIG. 4, and the exploded perspective view of FIG. The phosphor can be formed into a film and a wide wavelength band can be obtained by using a plurality of mixtures, and the absorption can be minimized by hitting other particles. White particles and transparent particles can be mixed with the ratio of the excitation light to the numerical value obtained by dividing the total amount of fluorescence by the conversion efficiency to obtain the desired spectral characteristics. As the white particles, a highly reflective material such as magnesium oxide (reflectance: 0.98), silica, or titanium oxide is suitable. As the transparent material, a glass or a transparent polymer having a high transmittance and a high softening temperature is suitable. The color balance can be improved by equalizing the transmitted light amount of the excitation light forward and the reflected light amount of the excitation light toward the fluorescent mirror.

Example 2
An embodiment of a bullet-type white light emitting diode in which a concave mirror around the light emitting element is provided on one lead and a fluorescent reflecting concave mirror is provided on the other lead will be described. The bullet-type light emitting diode is divided into a lead for mounting the light emitting element and a lead for supplying current, but the lead for mounting the light emitting element is provided with a concave mirror around the light emitting element, and the current supply lead is provided with a fluorescent reflecting concave mirror to bond the bonding wire to the light emitting element Connected to. When the concave mirror surrounding the light emitting element and the fluorescent reflecting concave mirror are integrated, the bonding wire becomes long because of the deep concave mirror, but the length can be shortened by dividing the wire.
The fluorescent reflecting concave mirror is a parabolic mirror with an open optical axis, avoiding the front convex lens, and redirecting the light toward the outer peripheral direction with the refractive surface to match the directivity of the convex lens in front of the phosphor. . When the light is emitted obliquely above the phosphor, it enters the conical refracting surface. Therefore, a reflecting mirror also serving as a light shield is provided and reflected to the fluorescent reflecting concave mirror.

Example 3
Implementation of a surface-mount element that converts fluorescence diffused forward from the phosphor film into parallel light with a parabolic mirror, converts the fluorescent reflection concave mirror into a parabolic mirror, converts it into parallel light, and then emits it in the vertical direction with a plane mirror An example will be described. The light source unit has a thin structure in which the elliptical mirror is divided into vertical halves and the light emitting element is directed toward the elliptical mirror and the elliptical mirror is in the horizontal direction. The fluorescent reflecting parabolic mirror is a semicircular shape using the upper half, and is a structure in which fluorescence is converted into parallel light and then emitted in the vertical direction by a plane mirror inclined at 45 °. The fluorescence in front of the phosphor is emitted in the vertical direction by a parabolic mirror so as to coincide with the light emitted from the plane mirror. A front parabolic mirror and a plane mirror can be provided on the heat dissipation board on which the light emitting element is placed. After the phosphor is placed when molding the transparent resin, the whole is molded, and an elliptical mirror and a parabolic mirror are deposited, electroless It is possible to manufacture a surface-mount element that is formed by plating or the like and emits parallel light.

Example 4
A white light source covering the visible light range by mixing a fluorescent white light emitting diode using a phosphor centered on yellow with a blue light emitting diode and a fluorescent white light emitting diode using a phosphor centered on orange with a blue green light emitting diode. A vehicle headlamp will be described as an embodiment of the apparatus. It can be applied to spotlights by changing the radiation angle.
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. The fluorescent material that receives the excitation light emits fluorescence to the rear elliptical mirror, and is converted into parallel light by the convex mirror and irradiated in the direction of the reflection grating. ing.
If the vertical emission angle of the vehicular headlamp is 10 °, the error angle 4 ° due to the size of the phosphor film is subtracted to set the emission angle γ in the orthogonal direction to the reflection grating 6 °. For this reason, the reflection grating is a convex reflection surface, the apex inclination α for determining the radiation angle γ is equal to the inclination α of the incident light, and the relationship between the valley inclination β is shown in Equation 5.

From Equation 5, 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. 14 is a side view of a configuration in which convex reflection gratings with wave number 4 are arranged, and FIG. 15 is a front view of a vehicle headlamp.
When a forward current of 40 mA is passed through the light-emitting element, 0.28 W is achieved with one unit composed of two light sources, and this unit is used in a total of 88 units of 11 rows horizontally and 8 rows vertically, with a conversion efficiency of 60 lm / W. A light beam of 1480 lm 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, when the lower five rows are turned on, the light becomes 920 lm, and a cut-off line can be provided in the unit arrangement as shown in FIG. 15 to increase the antiglare effect on the oncoming vehicle. The oblique reflection grating in the cut-off line is a trapezoidal reflection grating that combines an elliptical mirror and a hyperbolic mirror. FIG. 15 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 30 mm wide mounting space is provided around the reflection grating unit, 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 of wind speed u = 10 m / s (36 km / h) or more, the temperature rise is about 25 ° C. according to Equation 6. Since the heat conduction from the heat sink to the entire wall surface of the duct can be used for heat dissipation, the temperature rise can be lowered below about 25 ° C. Since Equation 6 uses the physical property value of air at the heat sink temperature, it must be repeatedly calculated, but the physical property value at 50 ° C. near the convergence condition Prandtl number Pr: 0.71
Thermal conductivity λ: 0.0241 [W / m ° C.]
Kinematic viscosity coefficient ν: 1.86 × 10 −5 [m 2 / s]
Is used to obtain the Reynolds number Re, the Nusselt number Nu, the average heat transfer coefficient α, and the temperature rise T from Equation 6. The vertical dimension L and horizontal dimension W of the heat sink are set, and the outside air temperature is 20 ° C.

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 dispersion film 8: elliptical mirror 10: convex refractive surface 11: concave Refractive surface 12: Fluorescent particles 13: White particles 14: Transparent particles 15: Refraction grating 16: Excitation light 17: Fluorescence 18: Translucent material 19: Parallel light 20: Diffused light 21: Concave mirror 22: Convex mirror 23: Aperture 25: Planar reflecting surface 26: light shield 29: substrate 33: ellipse 35: terminal 36: bonding wire 40: focal point 44: cut-off line

Claims (5)

The opening of the concave mirror around the light emitting element provided with the light emitting element is matched with the hole provided in the top of the fluorescent reflecting concave mirror ,
Plus the structure is molded with a transparent resin is provided at least phosphor phosphor dispersed film particles dispersed was formed on a thin film in the vicinity of the focal point of the fluorescence reflecting concave mirror transparent material,
The fluorescence emitted from the phosphor particles of the phosphor dispersion film to the half space in the transmission direction is directly emitted from the phosphor dispersion film from the light emitting element ,
A fluorescence-converting light-emitting diode , wherein fluorescence emitted from a phosphor dispersion film to a half space on the light-emitting element side is reflected by a fluorescent reflecting concave mirror and emitted. The phosphor dispersion film phosphor converted light emitting diode according to claim 1, characterized in that it consists structure formed into a thin film by kneading at least the phosphor particles in a transparent resin. The phosphor dispersion film phosphor converted light emitting diode according to claim 1, characterized in that it consists structure formed into a thin film by adhering at least the phosphor particles in a transparent film. The phosphor dispersion film by dispersing phosphor particles and white particles in a transparent material is formed on the thin film structure or Rannahli,
Fluorescence emitted in the direction of transmitting through the phosphor dispersion film is emitted directly,
The fluorescence-converted light-emitting diode according to claim 1, wherein the fluorescence emitted in the half space on the light-emitting element side from the phosphor-dispersed film and the excitation light reflected by the white particles are reflected and emitted by the fluorescence reflecting concave mirror. . Claims wherein the light emitting element is provided on one lead around the concave mirror is provided with a fluorescent reflecting concave mirror to the other lead, characterized by Rukoto such a structure of connecting the bonding wire to the light emitting element from the hole near the top of the fluorescence reflection concave mirror 2. The fluorescence conversion light emitting diode according to 1 .