Patent Application
20160139401
1. Field of the Invention
The present invention relates to a glass phosphor color wheel and methods for producing the glass phosphor color wheel and, more particularly, to a color wheel formed by directly melting, sintering, or bonding a glass material with fluorescent powder.
2. Description of the Related Art
Current projectors generally include a digital micromirror device (DMD) and use a color wheel to separate and handle colors. The color wheel generally includes red, green, and blue filters as well as filters of other colors. When used in a projector of a DMD projecting system, the white light emitted by the power source of the projector is focused on the color wheel by a lens. The color wheel is driven by a high speed motor of the projector, splits the white light from the power source into colors, and projects the beams of colored lights onto a surface of the DMD. Then, the DMD projects the reflected beams out of the projector through the lens.
The color wheel of conventional projectors generally uses fluorescent gel produced after mixing a polymer gel (such as silica gel) and fluorescent powder. The polymer gel has poor thermal stability. The fluorescent gel deteriorates when the power of the exiting light source increases. For example, the silica gel can only withstand about 150° C. and about 2000 lumens. If the temperature is higher than 150° C., the silica gel will age and yellow, causing damage to the color wheel. Thus, the color wheel using silica gel cannot be used in optical systems operating at a high temperature or a high lumen.
Thus, a need exists for a novel color wheel and methods for producing the color wheel.
An objective of the present invention is to provide a color wheel resistant to high temperature such that the color wheel can be used in an optical system of a projector operating at a high temperature or a high lumen, prolonging a service life of the color wheel.
The present invention fulfills the above objective by providing a glass phosphor color wheel including a wheel body made of a glass phosphor. The glass phosphor is formed by sintering a glass material and fluorescent powder. The fluorescent powder is a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, silicate, aluminate, and oxynitride. The glass material is selected from the group consisting of a silicate system, a phosphor system, a borate system, and a tellurate system.
The glass phosphor color wheel can further include a substrate having a first face and a second face opposite to the first face. The substrate further includes a through-hole in a center thereof. The color wheel is coupled to the first face of the substrate.
The fluorescent powder can have a doping rate not larger than 50 wt %. The wheel body can include a primary color board and at least one mixing color board. Each of the primary color board and the at least one mixing color board is made of a glass phosphor formed by sintering a glass material and at least one different fluorescent powder. Fluorescent lights of different colors are adapted to be excited when light rays pass through the primary color board and the at least one mixing color board.
The at least one mixing color board can be fixed to the primary color board. The glass phosphor color wheel can further include a substrate having a first face and a second face opposite to the first face. The color wheel is coupled to the first face of the substrate.
In an embodiment, the primary color board and the at least one mixing color board are fixed to the first face of the substrate.
In an embodiment, the at least one color mixing board includes a plurality of color mixing boards spaced from each other, and the plurality of color mixing boards separates the primary color board into a plurality of color segments.
In another embodiment, the at least one color mixing board includes a plurality of color mixing boards adjacent to each other.
In an embodiment, the wheel body includes an incident face and a bottom face opposite to the incident face. The glass phosphor color wheel further includes a first coating and a second coating. The first coating is coupled to the incident face. The first coating has a thickness equal to an odd multiple of a quarter of a wavelength of a light adapted to be incident to the incident face. The first coating includes an anti-reflection coating. The second coating coupled to the bottom face.
In an embodiment, the first coating has a refractive index n, the glass phosphor color wheel has a refractive index ns, and air has a refractive index n0, wherein n2=n0*ns.
In an embodiment, the first coating further includes a narrow bandpass, and the second coating is a notch filter.
In another embodiment, the second coating is a highly reflective coating.
Each of the first coating and the second coating can be a single layer film, a dual-layer film, or a multilayer film.
In another aspect, a method for producing a glass phosphor color wheel includes:
(a) a mold producing step including concentrically placing an inner tube into an outer tube, with at least one receiving space defined between the outer tube and the inner tube;
(b) a material feeding step including placing a glass phosphor material into the at least receiving space, with the glass phosphor material including a glass material and fluorescent powder, wherein the fluorescent powder is a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, silicate, aluminate, and oxynitride, 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; and
(c) a formation step including forming the glass phosphor material in the at least one receiving space into a wheel body.
The formation step can include: (c1) a heating step including melting the glass material to envelope the fluorescent powder to form the glass phosphor, and fusing the glass material, the outer tube, and the inner tube together; and (c2) a cooling step including solidifying the glass phosphor.
The method can further include a cutting step (d) after the formation step (c). The cutting step (d) includes cutting the wheel body to form a plurality of color wheels.
The method can further include a polishing step (e) after the cutting step (d). The polishing step (e) includes polishing a face of each of the plurality of color wheels.
In a further aspect, a method for producing a glass phosphor color wheel includes:
(A) a sintering step including sintering a glass material and fluorescent powder at a temperature of 500-1000° C. to form at least one glass phosphor color block, wherein the fluorescent powder is a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, silicate, aluminate, and oxynitride, 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; and
(B) a formation step including coupling the at least one glass phosphor color block to a substrate to form a glass phosphor color wheel.
The advantages of the glass phosphor color wheel and the methods for producing the glass phosphor color wheel according to the present invention are that the glass phosphor color wheel resistant to high temperature can be used as the color wheel for projectors. Thus, the temperature-resistant color wheel according to the present invention can be used in optical systems operating at a high temperature or a high lumen while prolonging the service life of the color wheel.
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 glass phosphor color wheel and methods for producing the glass phosphor color wheel will now be set forth in connection with the accompanying drawings wherein like elements are designated by like reference numbers.
With reference to
The substrate 20 is made of metal (such as stainless steel or aluminum) or ceramic material. The substrate 20 is a circular disc and includes a through-hole 21 in a center thereof. The substrate 20 includes a first face 201 and a second face 202 opposite to the first face 201. The through-hole 21 extends from the first face 201 through the second face 202. An outer wall 22 and an inner wall 23 are respectively formed on an outer peripheral edge and an inner peripheral edge of the first face 201, defining an annular groove 24 between the outer wall 22, the inner wall 23, and the substrate 20.
The wheel body 30 is made of a glass phosphor 31. The glass phosphor 31 is formed by sintering a glass material 311 and fluorescent powder 312. The glass material 311 is selected from the group consisting of a silicate system, a phosphor system, a borate system, and a tellurate system. The fluorescent powder 312 is a fluorescent material selected from the group consisting of yttrium aluminum garnet (YAG), nitride, silicate, aluminate, and oxynitride. Furthermore, the fluorescent powder 312 has a doping rate not larger than 50 wt %. The wheel body 30 is coupled to the first face 201 of the substrate 20. Specifically, the wheel body 30 can be embedded in the annular groove 24 by a colloid 32. The wheel body 30 includes at least one color block 33. In this embodiment, the wheel body 30 includes four color blocks 33. The size and color of each color block 33 can be the same or different according to needs.
With reference to
(A) a sintering step including sintering a glass material 311 and fluorescent powder 312 at a temperature of 500-1000° C. to form at least one color block 33 of glass phosphor 31; and
(B) a formation step including coupling the at least one color block 33 to a substrate 20 to form a glass phosphor color wheel. The at least one color block 33 can be coupled to the substrate 20 through bonding or embedding by a colloid 32.
The glass phosphor 31 of the present invention is free of gel and is, thus, resistant to high temperature, avoiding the risk of deterioration. Thus, the color wheel made of glass phosphor can be used in high-power laser projector modules and can still possess inherent optical characteristics under high-power light sources. As a result, the color wheel can be used in optical systems operating at a high temperature or a high lumen while prolonging the service life of the color wheel.
In an embodiment shown in
In another embodiment shown in
In order to increase the light input and the light output of the glass phosphor color wheel, an anti-reflection coating can directly or indirectly be disposed on the glass phosphor color wheel. In an embodiment shown in
A first coating 51 is coupled to the incident face 501 and has a thickness equal to an odd multiple of a quarter of a wavelength of a light adapted to be incident to the incident face 501. The first coating 51 includes an anti-reflection coating and a narrow bandpass. The first coating has a refractive index n, the glass phosphor color wheel has a refractive index ns, and air has a refractive index n0, wherein n2=n0*ns.
A second coating 52 is coupled to the bottom face 502. The second coating 52 is a notch filter.
The anti-reflection coating is directly or indirectly provided on the glass phosphor color wheel 50 to increase the light input and the light output of the glass phosphor color wheel 50. The anti-reflection coating can be formed on the glass phosphor color wheel by photonic crystals, nanoimprinting, semiconductor coating techniques, or laser microlithography. Each of the first coating 51 and the second coating 52 can be a single layer film, a dual-layer film, or a multilayer film. Thus, when the incident light R1 enters the glass phosphor color wheel 50, deflection and reflection of the light ray are avoided. Furthermore, when the light R2 in the glass phosphor color wheel 50 exits and becomes an emergent light R3, deflection and reflection of the light ray are also avoided. Thus, the light transmission percentage can be increased to be 98% of the incident light R1, effectively increasing the projector luminance.
In another embodiment shown in
The present invention further includes a method for integrally producing a glass phosphor color wheel. With reference to
(a) a mold producing step: An inner tube 64 is placed into an outer tube 63, as shown in
(b) a material feeding step: A glass phosphor material 75 is placed into the at least one receiving space 65, as shown in
(c) a formation step: The glass phosphor material 75 in the at least one receiving space 65 is formed into a wheel body 70, as shown in
Furthermore, the glass material 721, the outer tube 63, and the inner tube 64 are fused together. Specifically, the glass material 721 is heated to a predetermined temperature and, thus, melt. However, the fluorescent powder 722 does not melt at the predetermined temperature. Thus, the glass material 721 directly melts and envelopes the fluorescent powder 722. Furthermore, the glass material 721, the outer tube 63, and the inner tube 64 are fused together. The melting point of the glass material 721 is generally about 650° C. The melting point of the fluorescent powder 722 is higher than 650° C. Thus, the predetermined temperature is higher than 650° C. but lower than the melting point of the fluorescent powder 722.
The cooling step (c2) includes solidifying the glass phosphor 72. Since the outer tube 63 and the inner tube 64 are made of aluminum oxide or even quartz, they can bond excellently with the glass material 721. Thus, the structural strength can be enhanced, and the outer and inner tubes 63 and 64 can be fused with the glass material 721. Production of the wheel body is, thus, accomplished.
Furthermore, the method can further include a cutting step (d) after the formation step (c) by cutting along the phantom lines shown in
Furthermore, the method can further include a polishing step (e) after the cutting step (d). The polishing step (e) includes polishing a face of each color wheel.
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.
