Patent Application
20160139300
1. Field of the Invention
The present invention relates to a lens that can be used in a white light illuminating module or used as a packaging structure of a light-emitting diode.
2. Description of the Related Art
Recently, white light emitting diodes have gradually replaced conventional lights and have received attention from the consumers due to the advantages of long service life, small volume, and excellent light emitting efficiency.
Generally, if the heat generated during light emission of a light emitting diode cannot be guided to the outside, the temperature of the interface of the light emitting diode will become too high and, thus, adversely affect the service life, the light emitting efficiency, and stability. For example, when a blue chip is used in a high luminance situation requiring a higher power, the heat generated on the surface of the blue chip causes rapid deterioration of the silica gel, leading to increased loss of lumen, severe chromaticity shift, and unstable quality of the lighting source.
On the other hand, since glass has excellent transmittance to light and can evenly be mixed with fluorescent powder, glass materials with better resistance to heat have been proposed to replace silica gel to mix with fluorescent powder for sintering, forming a glass phosphor with characteristics of both of glass and fluorescence. This significantly removes the inherent temperature limitations to polymer materials. The glass phosphor can be used as an LED packing material that is less easily to age under the heat energy from the LED chip.
However, the processing temperature of the glass materials are generally above 1000° C., which not only increases difficulties in the process but is apt to destruct the fluorescent property of the fluorescent powder during the high temperature process.
Thus, a need exists for a novel method for producing a low temperature glass phosphor lens and a lens produced by the method.
An objective of the present invention is to provide a method for producing a low temperature glass phosphor lens and a lens produced by the method. A thermally stable glass phosphor lens produced at a low processing temperature is, thus, provided.
The present invention fulfills the above objective by providing a method for producing a low temperature glass phosphor lens. The method includes: (a) a mixing step including dry mixing a glass material and fluorescent powder to form a powdery or particulate mixture; (b) a mixture grinding step including grinding the mixture to a diameter of 15-20 μm, obtaining uniformly mixed glass fluorescent powder; (c) a hot pressing formation step including hot pressing the glass fluorescent powder into a glass phosphor at a temperature of 500-1000° C.; and (d) a processing formation step including grinding and polishing the glass phosphor into a lens.
The glass material in the mixing step can be obtained by: (a1) a low temperature sintering step including placing a glass in a container and carrying out low temperature sintering at a temperature of 1000-1500° C.; (a2) a quenching formation step including placing the glass into water, alcohol, or liquid nitrogen to cool the glass, forming the glass material after the glass is cooled; and (a3) a grinding step including grinding the glass material to a diameter of 15-20 μm.
The fluorescent powder can be a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, and silicate, and the glass material can be selected from the group consisting of a silicate system, a phosphor system, a borate system, and a tellurate system.
The glass material can include 70 wt % of SiO2, 20 wt % of Na2O, 7 wt % of Al2O3, and 3 wt % of CaO.
In another aspect, a low temperature glass phosphor lens is produced by the method, wherein the fluorescent powder is a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, and silicate, and wherein the glass material is selected from the group consisting of a silicate system, a phosphor system, a borate system, and a tellurate system.
The lens can be a plane lens, an aspheric lens, or a microlens.
In an embodiment, a polymethylmethacrylate (PMMA) lens is boned to the lens.
In embodiments, the lens extends across two ends of a substrate, and a chip is mounted between the substrate and the lens. The chip is adapted for generating a light source, and the light source emits outward through the lens.
The advantages of the method for producing a low temperature glass phosphor lens and the lens produced by the method are that the silica gel of the prior art is replaced with the glass material to mix and sinter with the fluorescent powder, forming a glass phosphor including characteristics of both of glass and fluorescence. Thus, the glass phosphor can be used as an LED packing material that is less easily to age under the heat energy from the chip of an LED. Furthermore, the processing temperature is controlled to be below 1000° C., which not only reduces the equipment costs but keeps the structure of the fluorescent powder in a stable state.
The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.
A method for producing a low temperature glass phosphor lens and a lens 20 produced by the method will now be set forth in connection with the accompanying drawings wherein like elements are designated by like reference numbers.
With reference to
Diffusion can be reduced when the stable crystalline structure of the fluorescent powder including yttrium aluminum garnet is sintered together with amorphous soda glass, maintaining good optical characteristics. Furthermrore, addition of nitride and silicate increases the color rendering index (Ra). The glass according to the present invention is soda glass that is highly resistive to corrosion and heat after modification to the properties. The fluorescent powder is selected from the group consisting of yttrium aluminum garnet, nitride, and silicate, forming an optical material with a wide color gamut and an adjustable color gamut.
Preferably, the glass material includes 70 wt % of SiO2, 20 wt % of Na2O, 7 wt % of Al2O3, and 3 wt % of CaO. Since the proportion of silicon dioxide is increased, the glass structure can be more stable. Furthermore, the composition is modified by adding calcium oxide for the purposes of preparing an organic glass material with high reliability. This prevents easy hydrolysis and fogging resulting from a loose glass structure and, thus, avoids degradation of the transmittance of the glass and resultant adverse effects on the optical characteristics of the glass phosphor lens.
As for implementation of the present invention, please refer to
The lens 20 is a curvature structure with a curved face and extends across two ends of the substrate 30. The chip 31 is received between the substrate 30 and the lens 20. The light source generated by the chip 31 emits outward through the lens 20.
The method for producing a low temperature glass phosphor lens according to the present invention is carried out by using the glass material 22 and the fluorescent powder 23. The method includes:
(a) a mixing step: the glass material 22 and the fluorescent powder 23 are mixed by dry mixing to form a powdery or particulate mixture. As an example, the glass material 22 and the fluorescent powder 23 are placed in a rotational mixer and are stirred and mixed for 30-60 minutes to obtain the mixture.
(b) a mixture grinding step: the mixture is grinded to a diameter of 15-20 μm, obtaining uniformly mixed glass fluorescent powder. As an example, the mixture is grinded in a mortar for 20-30 minutes to obtain the glass fluorescent powder. Thus, the particle size of the mixture after grinding can match the particle size of the fluorescent powder, providing an optical proportion of mixing and melting. In addition to excellent fluorescent uniformity, an appropriate surface area of the glass fluorescent powder can be obtained to effectively reduce the diffusion during contact sintering between the glass powder and the fluorescent powder, thereby reducing the quantum efficiency.
(c) a hot pressing formation step: the glass fluorescent powder is hot pressed into a glass phosphor 21 at a temperature of 500-1000° C.; and
(d) a processing formation step: the glass phosphor 21 is grinded and polished into a lens 20.
The glass material 22 in the mixing step can be obtained by:
(a1) a low temperature sintering step: glass is placed in a container, and low temperature sintering is carried out at a temperature of 1000-1500° C.;
(a2) a quenching formation step: the glass is placed into water, alcohol, or liquid nitrogen to cool the glass, forming the glass material 22 after the glass is cooled; and
(a3) a grinding step: the glass material 22 is grinded to a diameter of 15-20 μm.
The structural type of the lens 20 can be different according to actual needs. The lens 20 can be a single glass phosphor lens or can cooperate with an optical film with light field correction characteristics. In the embodiment shown in
The present invention replaces the silica gel of the prior art with the glass material 22 to mix and sinter with the fluorescent powder 23, forming a glass phosphor 21 including characteristics of both of glass and fluorescence. Thus, the glass phosphor 21 can be used as an LED packing material that is less easily to age under the heat energy from the chip of an LED. Furthermore, the processing temperature is controlled to be below 1000° C., which not only reduces the equipment costs but keeps the structure of the fluorescent powder 23 in a stable state. Furthermore, by mixing the fluorescent powder 23 with the glass material 22, functions of both of a color change medium and a lens can be obtained. Thus, effects of color change and light field correction can be obtained.
Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the scope of the invention. The scope of the invention is limited by the accompanying claims.
