Efficient and uniform laser-excited white light generator

Abstract

A white light source comprises: a light emitting layer comprising a phosphor and a light scattering material arranged in an adhesive; and a light source arranged to illuminate the light emitting layer with blue light. The white light source outputs white light, which comprises converted phosphor emission light from the phosphor illuminated by the blue light, and unconverted scattered blue light scattered by the light scattering material. The unconverted scattered blue light has a spatial distribution that matches the spatial distribution of the converted phosphor emission light. In some embodiments, the spatial distribution is approximately a Lambertian spatial distribution. The white light source may include a phosphor wheel, the phosphor wheel including a disk-shaped substrate, and the light emitting layer is arranged as a phosphor ring on the disk-shaped substrate. The phosphor ring may include a phosphor and a light scattering material having a uniform composition arranged in an adhesive near an annular region in the phosphor ring.

Description

[0001] This application is a divisional application of the patent application with application number 2018800914413, application date April 28, 2018, and invention name “High-efficiency and uniform laser-excited white light generator”. Technical Field

[0002] The following relates to lighting technology, phosphor wheel technology, optical interference filter manufacturing technology and related technologies. Background Art

[0003] It is known to use phosphors of different colors excited by blue LEDs or laser diodes to produce white light.

[0004] For most digital light projection (DLP) projectors, a phosphor wheel works as a second light source and is excited by a blue laser diode to produce green, yellow, and red light in rapid temporal sequence as the phosphor wheel rotates. These various colors of light are combined with the blue light to produce white light for the DLP projection system. Most phosphor wheels are reflective types with multiple color segments. In order to combine these different colors of light, corresponding optical paths and color mixing hardware are provided.

[0005] This article discloses some improvements. Summary of the invention

[0006] In one disclosed aspect, a phosphor wheel is provided, which includes a disk-shaped substrate and a phosphor ring, the phosphor ring including an annular light-emitting layer arranged on the disk-shaped substrate. The annular light-emitting layer includes a phosphor and a light-scattering material arranged in a binder. In some embodiments, the light-scattering material includes light-scattering particles arranged in a binder. In some embodiments, the light-scattering particles have a size in the range of 0.1 to 50 microns. In some embodiments, the light-scattering particles have a reflectivity of more than 92%. In some embodiments, the light-scattering particles include one or more of aluminum oxide particles, titanium dioxide particles, magnesium oxide particles, boron nitride particles, aluminum nitride particles, and aluminate particles. In some embodiments, the annular light-emitting layer includes a phosphor and a light-scattering material having a uniform composition arranged in a binder near an annular region in the annular light-emitting layer. In some embodiments, the phosphor wheel also includes a motor, which is operably connected to rotate the disk-shaped substrate. These different embodiments can be combined in different ways.

[0007] In another disclosed aspect, a white light source is disclosed, comprising: the phosphor wheel described in the previous paragraph; and a blue light source arranged to illuminate the phosphor ring with blue light. The white light source outputs white light, which includes converted phosphor emission light from the phosphor illuminated by the blue light, and unconverted scattered blue light scattered by the light scattering material. In some embodiments, the unconverted scattered blue light has a spatial distribution that matches the spatial distribution of the converted phosphor emission light. In some embodiments, the unconverted scattered blue light has a diffuse surface spatial distribution, and the converted phosphor emission light has a diffuse surface spatial distribution. In some embodiments, the blue light has a wavelength in the range of 400nm to 500nm. In some embodiments, the converted phosphor emission light includes yellow light. In some embodiments, the phosphor comprises a mixture of a red phosphor that produces converted phosphor emission light in a red light spectrum ranging from 600 to 650 nm and a green phosphor that produces converted phosphor emission light in a green light spectrum ranging from 490 to 560 nm. In some embodiments, the phosphor wheel is a reflective phosphor wheel. In some embodiments, the phosphor wheel is a transmissive phosphor wheel. These different embodiments can be combined in different ways.

[0008] In another disclosed aspect, a white light source is disclosed, comprising: a light emitting layer comprising a phosphor and a light scattering material disposed in a binder; and a light source disposed to illuminate the light emitting layer with blue light. The white light source outputs white light, which includes converted phosphor emission light from the phosphor illuminated by the blue light, and unconverted scattered blue light scattered by the light scattering material. In some embodiments, the light scattering material comprises light scattering particles disposed in the binder. In some embodiments, the light scattering particles have a size in the range of 0.1 to 50 microns. In some embodiments, the light scattering particles have a reflectivity of 92% or more to blue light. In some embodiments, the light scattering particles include one or more of aluminum oxide particles, titanium dioxide particles, magnesium oxide particles, boron nitride particles, aluminum nitride particles, and aluminate particles. In some embodiments, the unconverted scattered blue light has a spatial distribution that matches the spatial distribution of the converted phosphor emission light. In some embodiments, the unconverted scattered blue light has a diffuse surface spatial distribution, and the converted phosphor emission light has a diffuse surface spatial distribution. In some embodiments, the blue light has a wavelength in the range of 400nm to 500nm. In some embodiments, the converted phosphor emission light comprises yellow light. In some embodiments, the phosphor comprises a mixture of a red phosphor that produces converted phosphor emission light in a red light spectrum ranging from 600 to 650 nm and a green phosphor that produces converted phosphor emission light in a green light spectrum ranging from 490 to 560 nm. These different embodiments can be combined in different ways.

[0009] In another disclosed aspect, a method for generating white light is disclosed. A portion of blue light is converted into phosphor light by a phosphor arranged in a light-emitting layer. The portion of the blue light that is not converted into phosphor light is scattered by scattering particles arranged in the light-emitting layer to generate scattered blue light. White light is output, and the white light includes a combination of phosphor light and scattered blue light. In some embodiments, the phosphor light has a diffuse surface spatial distribution, and the scattered blue light has a diffuse surface spatial distribution. In some embodiments, while converting, scattering, and outputting, a phosphor wheel is rotated, wherein the phosphor wheel includes a disk-shaped substrate, and the light-emitting layer is arranged as a phosphor ring on the disk-shaped substrate. In some embodiments, the phosphor wheel is a reflective phosphor wheel, and the white light is output on the same side of the phosphor wheel as the side illuminated by the blue light. In some embodiments, the phosphor wheel is a transmissive phosphor wheel, and the white light is output on the side of the phosphor wheel opposite to the side illuminated by the blue light. These different embodiments can be combined in different ways. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 An exemplary white light source operating in reflective mode is schematically shown.

[0011] Figure 1A Various spatial distributions of light emitted from a surface as described herein are depicted.

[0012] Figure 2 An exemplary white light source operating in transmissive mode is schematically shown.

[0013] Figure 3 Schematically shows the combination of Figure 1 A reflective phosphor wheel with a white light source.

[0014] Figure 4 Schematically shows the combination of Figure 2 Transmissive phosphor wheel for white light source.

[0015] Figure 5 Schematically shows the combination of Figure 1 A reflective static white light source.

[0016] Figure 6 Schematically shows the combination of Figure 2 A transmissive static white light source. DETAILED DESCRIPTION

[0017] Obtaining white light directly from the phosphor wheel will simplify the projection system. In principle, different phosphors can be mixed together to produce white light with desired properties, thus providing more solutions for customers of DLP or LCD projectors.

[0018] However, efficient generation of white light by this approach is hampered by the very different spatial distribution of the phosphor emitted light (approximately Lambertian), and by the direct blue laser light being a narrow-angle beam.

[0019] Embodiments of directly obtaining white light using a phosphor wheel excited by a blue laser diode are disclosed herein. To address the large spatial distribution mismatch, the phosphor (which typically includes a yellow phosphor, but may also include other phosphor components, such as a mixture of green and red phosphors) is mixed with a light scattering material that has high reflectivity for blue light. In one suitable physical configuration, the mixture of phosphor and light scattering material is dispersed in a binder, and the phosphor / scattering material / binder composition is deposited on a reflective substrate or a light-transmitting substrate by dispensing or silk printing or other suitable coating methods.

[0020] The disclosed method provides many benefits, such as (but not limited to): adjustable color temperature (e.g., in the range of 4000 to 8000K, depending on the spectral characteristics of the phosphor-emitted light and the blue laser); providing a spatial distribution of non-excited blue light that is close to the spatial distribution of yellow light emitted by the phosphor; the white light source can be designed as a transmissive source or a reflective source; it is simple to manufacture; high white light output efficiency can be achieved; and good spatial uniformity of white light output can be achieved.

[0021] The disclosed white light source produces white light, which includes a combination of direct blue light emitted by an LED or laser and converted phosphor emission light (e.g., yellow light) to produce white light, and the white light source also includes a high-reflectivity light scattering material, which is added to improve the uniformity of the direct blue light, that is, to adjust the spatial distribution of the direct blue light to match the (approximately Lambertian) phosphor emission. After being scattered by the reflective material, the spatial distribution of the blue light is generally close to a Lambertian shape. Therefore, the spatial distribution of the scattered direct blue light matches the approximately Lambertian spatial distribution of the converted yellow light emitted by the phosphor. The binder mixed with the phosphor and the light scattering material can be an organic binder or an inorganic binder.

[0022] The disclosed light sources can be used in conjunction with a reflective phosphor wheel or a transmissive phosphor wheel. It is also contemplated that the disclosed light sources can be used in conjunction with other types of light emitters, such as light emitters that use a static phosphor layer that is not mounted on a rotating wheel. The disclosed light sources are easy to manufacture at low cost for use in either reflective or transmissive designs. The disclosed methods are also suitable for providing white light with high brightness by using a high power laser diode or other high power blue light source. In this case, the use of a high power blue laser in conjunction with a rotating phosphor wheel having the disclosed phosphor / scattering particle dispersion has the significant advantage of distributing the heat generated by the laser over an annular area on the rotating wheel drawn by the laser impingement path.

[0023] White light is produced by a combination of direct blue light and light converted by a yellow phosphor. The blue light is unexcited (i.e., direct) blue light provided by a laser diode or LED, and the yellow light is converted light from a phosphor that converts a portion of the blue light (i.e., excited blue light) to emit yellow light. In some embodiments, the wavelength range of the blue light is in the range of 400nm to 500nm, and more preferably in the range of 400 to 480nm. The lower limit of the shortest wavelength of visible blue light that is usually perceptible to humans is 400nm (normally humans cannot perceive shorter wavelengths as ultraviolet light). The upper limit of the maximum wavelength of blue light that is usually perceptible to humans is usually about 480nm, and the upper limit of the wavelength of blue-green light that is usually perceptible to humans is 500nm. However, it is possible to consider using a laser or LED that emits direct light in the aforementioned range of 400 to 500 nm, or more preferably in the range of 400 to 480 nm, which laser or LED also has some longer wavelength components (such as green and / or yellow light components) and / or some shorter wavelength components (such as some ultraviolet components).

[0024] In some non-limiting exemplary embodiments, a yellow phosphor is excited by a blue laser, wherein the phosphor particle size is 1 to 50 microns (although larger or smaller phosphor particle sizes are also contemplated; furthermore, all particle, particulate, or similar sizes specified herein are to be understood as average or mean sizes), and exemplary yellow phosphors include yttrium aluminum garnet doped with cerium (YAG:Ce), terbium aluminum garnet doped with cerium (TAG:Ce), barium orthosilicate doped with europium (BOS), or other suitable phosphors to effectively convert blue light into longer wavelength visible light, such as yellow light. As disclosed herein, in order to improve the uniformity of the blue light, a highly scattering material with high reflectivity is added to the mixture of the phosphor and the binder to scatter the blue light, thereby forming a distribution that is approximately Lambertian in shape close to the yellow light emission.

[0025] The scattering material preferably has a relatively high thermal conductivity, for example, in some embodiments, the thermal conductivity is 20W / m·K or more. The light scattering material preferably has a suitable CTE and density similar to the coefficient of thermal expansion (CTE) and density of the phosphor to promote uniform mixing of the phosphor and the light scattering material in the adhesive. The shape of the light scattering particles can be granular, spherical, flaky, fibrous, etc., and in some exemplary embodiments, the size of the light scattering particles is in the range of 0.1 to 50 microns, but larger or smaller particles can also be considered. The light scattering particles are preferably highly reflective to blue light (for example, in a suitable range of 400 to 480nm or 400 to 500nm), for example, in some embodiments, the reflectivity is more than 92% in the range of 400 to 480nm (or 500nm). The light scattering particles are preferably stable in a normal operating temperature range (for example, in some embodiments, -20 to 500 degrees Celsius). The upper operating temperature limit depends in part on the amount of heating of the phosphor / scattering particles / binder layer caused by the laser, and it is advantageous to reduce this heat through the operation of a rotating phosphor wheel that distributes the heat over the circular path of the laser beam passing through the rotating wheel. By way of non-limiting example, the light scattering material may, for example, include aluminum oxide particles, titanium dioxide particles, magnesium oxide particles, boron nitride particles, aluminum nitride particles, aluminate particles, or some combination of two or more of these.

[0026] In a variant embodiment, the phosphor powder mixed with the light scattering material described herein is bonded to a substrate using an adhesive. The adhesive can be, for example, an organic adhesive or an inorganic adhesive. Some suitable inorganic adhesives include silicates, phosphates, borates, etc. Some suitable organic adhesives include silicone resins, epoxy resins, polyurethanes, etc.

[0027] The substrate of the phosphor wheel or other white light source may include, for example, metal, metal alloy, or a mixture of metal and inorganic material, a reflector, ceramic, glass, sapphire plate, quartz plate, etc. A reflective substrate (e.g., metal) is advantageous for a reflective design, and its reflectivity is preferably at least 85%, and more preferably at least 90% or more. For example, a reflective substrate may be designed on the surface of a metal, glass, ceramic or other suitable substrate; however, if the density of the phosphor and light scattering particles is high enough, substantially all blue light may be converted by the phosphor into yellow light or scattered by the light scattering particles, in which case it is expected that the substrate may be light-transmissive even in the case of a reflective design. On the other hand, a light-transmissive substrate such as glass or quartz is suitable for a light-transmissive phosphor wheel or other light-transmissive white light source. (As used herein, the term "light-transmissive" and similar terms are intended to indicate a high transmittance of the generated white light, for example, 80% or more, and preferably 90% or more, depending on the long-wavelength extent of the designed white light, which is in the spectral range of at least 400 to 650 nm or 400 to 700 nm). In some exemplary embodiments, in the case of a phosphor wheel, the substrate is disk-shaped (disc-shaped); in the case of a static phosphor module, the substrate may be disk-shaped or rectangular, etc. In some exemplary embodiments, the phosphor / scattering material / binder composition has a composition weight ratio of 20% to 70% binder, 30% to 80% phosphor, and 5% to 15% scattering material. Higher or lower composition ratios are also contemplated; for example, thicker layers may allow for a higher binder to phosphor ratio and a higher binder to scattering material ratio.

[0028] Reference now Figure 1 , an exemplary white light source (100) operating in a reflective mode is shown, and the exemplary white light source includes a substrate (101), on which are arranged light-emitting layers (102, 103, 104), the light-emitting layers (102, 103, 104) including a binder (102), a yellow phosphor (103), and a light scattering material including light scattering particles (104). The reflectivity of the substrate (101) is preferably above 90%, and in some exemplary embodiments the substrate (101) has a thickness between 0.3 mm and 3 mm, but thicker or thinner substrates are also contemplated. It should be understood that the optimal substrate thickness depends on many factors, for example, in the case of a phosphor wheel, the substrate (101) is a rotating wheel and should have sufficient thickness to be rigid during rotation, and this thickness depends on the rotation rate, the stiffness of the material constituting the substrate (101), and other factors.

[0029] In operation, one or more laser diodes (LDs) emit excitation blue light (105a), which impinges on the light emitting layers (102, 103, 104). Alternatively, a blue LED may be used to emit the blue light (105a). Other light sources emitting suitable blue light are also contemplated. In response to the optical stimulus of the excitation blue laser (105a), the yellow phosphor (103) emits yellow light (106). Through this phosphor conversion process, only a portion of the incident blue light (105a) is converted into yellow light (106); the remaining blue light is scattered by the scattering particles (104), and the scattered blue light (105b) combines with the yellow phosphor emission light (106) to form reflected white light (105b, 106).

[0030] Brief reference Figure 1A , the typical spatial distribution of the light emitted by the yellow phosphor is a diffuse reflection surface spatial distribution. The ideal diffuse reflection surface spatial distribution is a Lambertian distribution, such as for the illustrated surface (120) Figure 1A As shown. The Lambertian spatial distribution has equal brightness when viewed from all directions in the half-space (122) adjacent to the surface (120). Physically achievable diffuse reflective surface spatial distributions are usually only approximately Lambertian. Figure 1A Also shown is a typical diffuse reflective surface spatial distribution for a yellow phosphor, which is only approximately Lambertian. It should be noted that in the case of phosphor emission light, the physical mechanism is not reflection, but rather absorption of blue light (105a) by the yellow phosphor (103) and subsequent emission of yellow converted phosphor light (106). However, although produced by a different mechanism, the phosphor emission light (106) has a diffuse reflective surface spatial distribution, which is shown in FIG. Figure 1A Similarly, the scattered blue light (105b) is generated by a slightly different mechanism than reflection from a diffuse surface because the light scattering particles (104) are distributed in depth across the thickness of the light emitting layer; nevertheless, the resulting spatial distribution is that of a diffuse reflecting surface, as shown in FIG. Figure 1A As shown, it is approximately Lambertian.

[0031] In order to obtain a desired light distribution of scattered blue light similar to the approximately Lambertian light distribution of yellow light (106), the density of the light scattering particles is preferably designed so that most or all of the direct blue light that is not converted into yellow light by the phosphor (103) encounters and is scattered from at least one light scattering particle (104). However, it is expected that a relatively small portion of the unconverted direct blue light is reflected by the substrate (101) without interacting with the phosphor (103) or the scattering particles (104).

[0032] In a typical conventional phosphor wheel for a laser projector, the goal is to convert all incident blue light into yellow light. Any remaining unconverted portion of the incident blue light is appropriately removed by a dichroic filter located downstream along the optical path of the projector system, so that only yellow light is emitted from the light-emitting layer. Figure 1 In the white light source (100), in order to obtain white light (105b, 106), a portion of the direct blue light is intentionally retained: this portion constitutes the unexcited blue light (105b) that does not stimulate the phosphor (103) to produce the yellow light (106). The light scattering particles (104) ensure that the direct blue light (105b) has a spatial distribution that matches the approximately Lambertian spatial distribution of the converted yellow light (106), so that the white light (105b, 106) thus generated is spectrally uniform on the approximately Lambertian distribution.

[0033] The white light (105b, 106) has a designed ratio of direct blue light (105b) and yellow light (106). The ratio of unexcited blue light and yellow light is adjusted by adjusting the relative ratios of the phosphor (103), the scattering material (104), the binder (102), the thickness of the light-emitting layers (102, 103, 104) and the particle size of the phosphor (103) and the scattering particles (104), so as to design the ratio. Among them, the thickness of the light-emitting layers (102, 103, 104) and the density of the phosphor (103) generally have the strongest influence on the ratio of blue light (105b) to yellow light (106) in the combined white light (105b, 106). The theoretical influence of the light-scattering particles (104) on the ratio is attributed to the absorption of the scattering particles (104), and since the scattering particles (104) preferably have a high reflectivity (e.g., above 90%), the absorption of the scattering particles (104) is preferably low. Nevertheless, if light is typically reflected multiple times by the light scattering particles (104), this absorption may be high enough that it should be taken into account. However, even in this case, if the reflection losses of blue and yellow light are similar (similar average number of reflections and similar reflectivity at the blue and yellow spectral regions), the effect of the light scattering particles (104) on the blue / yellow light ratio may be negligible.

[0034] By way of non-limiting example, in some embodiments, the light emitting layers (102, 103, 104) have a thickness of 0.05 mm to 0.3 mm, although thicker or thinner light emitting layers may also be considered based on optical design principles (such as those outlined above), depending on factors such as the relative ratios of the phosphor (103), scattering particles (104) and binder (102), and the particle size.

[0035] In an exemplary embodiment, the phosphor emission light (106) is described as yellow light. However, it should be understood that the phosphor emission light (106) can have a more complex spectrum, for example, the phosphor (103) can include a mixture of a red phosphor and a green phosphor, the mixture producing converted light having respective peaks in the red spectral range (~600 to 650nm) and the green spectral range (~490 to 560nm), respectively, and the combination of the converted light (106) having such a "double-lobed" spectrum with the direct (unconverted) blue light (105b) is visually perceived as white light. The detailed spectra of the direct blue light (105b) and the phosphor emission light (106) can be tailored to provide white light with desired whiteness characteristics, such as a desired color rendering index (CRI), a desired color temperature (e.g., a "cool" white light having a color temperature above about 4000K).

[0036] Reference now Figure 2 , an exemplary white light source (200) operating in a transmission mode is shown, and the exemplary white light source (200) includes a light-transmitting substrate (201), on which light-emitting layers (202, 203, 204) are arranged, and the light-emitting layers (202, 203, 204) include a binder (202), a yellow phosphor (203), and a light-scattering material including light-scattering particles (204). In some exemplary embodiments, the light-transmitting substrate (2) has a thickness between 0.1 mm and 3 mm, but thicker or thinner substrates are also contemplated. In some embodiments, the thickness of the light-emitting layers (202, 203, 204) is 0.01 mm to 0.2 mm, but thicker or thinner substrates are also contemplated. One or more laser diodes (LD) (or alternatively, one or more blue LEDs) illuminate the device from the substrate side, i.e., the laser light (205a) illuminates the substrate (201) on the side opposite to the substrate side where the light emitting layers (202, 203, 204) are arranged. Figure 1 As in the device of FIG. 2 , a portion of the direct laser light (205a) is converted by the phosphor (203) into converted yellow light (206), while another portion of the blue light passes through as unconverted blue light (205b), which is combined with the yellow light (206) to form white light (205b, 206). To improve optical efficiency, in some embodiments, the substrate (201) is coated with a dichroic film that allows the blue light (205a) to pass but reflects the yellow light (206).

[0037] As in Figure 1As in the embodiment of the present invention, the unconverted blue light (205b) is scattered by the scattering particles (204), and the scattered blue light (205b) is combined with the yellow phosphor emission light (206) to form reflected white light (205b, 206). In order to obtain a desired diffuse surface light distribution of the scattered blue light (205b) similar to the approximately Lambertian light distribution of the yellow light (206), the density of the light scattering particles (204) is preferably designed so that most or all of the direct blue light that is not converted into yellow light by the phosphor (203) encounters at least one light scattering particle (204) and is scattered from the at least one light scattering particle (204). However, it is expected that a relatively small portion of the unconverted direct blue light passes through the light emitting layer (202, 203, 204) without interacting with the phosphor (203) or the light scattering particles (204). It should also be noted that the diffuse surface spatial distribution of the scattered blue light (205) is similar to the diffuse reflection from a real diffuse reflecting surface, but the mechanism is slightly different due to the distribution of the scattering particles (204) across the thickness of the light-emitting layer, and in addition, the scattered light is produced by transmission rather than by a reflection process.

[0038] Figure 3 A phosphor wheel (300) is shown, which is configured to use Figure 1 The reflective white light source (100) is operated in a reflective mode. The YAG:Ce phosphor powder (103) and the scattering material (104) are mixed with the binder (102) and then dispersed on the metal substrate (302) (corresponding to Figure 1 In other words, the phosphor ring (301) is appropriately formed into Figure 1 The ring (301) may be appropriately cured by heating to harden the adhesive, depending on the type of adhesive (102). The phosphor wheel (300) is driven by a motor (303) and a coupling drive shaft (304) to move along the Figure 3 The motor (303) and the disc-shaped substrate (302) rotate in a clockwise direction as indicated by the curved arrow (305) in the figure (as an alternative, counterclockwise rotation can be envisioned), thereby rotating at a high speed. In addition to the drive shaft (304) or as an alternative to the drive shaft (304), other operative couplings between the motor (303) and the disc-shaped substrate (302) can be considered to motorize the rotation of the disc-shaped substrate (302), such as gears, right-angle mechanical linkages, etc. The excitation light (105a) is the incident light source. When the excitation laser beam (e.g., blue light (105a)) is focused on the phosphor ring (301) to form a light spot, the converted yellow light beam (106) is emitted and combined with the scattered blue light (105b) (as previously described with reference to Figure 1 Said), and will then be collected by a lens system (not shown).

[0039] Figure 4 A phosphor wheel (400) is shown, which is configured to use Figure 2 The transmissive white light source (200) is operated in a transmissive mode. The YAG:Ce phosphor powder (203) and the scattering material (204) are mixed with a binder (202) and then dispersed on a transmissive substrate (402) (corresponding to Figure 2 In other words, the phosphor ring (401) is appropriately formed into Figure 2 The substrate (402) is transparent, such as glass, crystalline ceramics, sapphire plate, etc. In some embodiments, depending on the type of adhesive (202), the ring (401) can be properly cured by heating to harden the adhesive. The phosphor wheel (400) is driven by a motor (403) and a coupling drive shaft (404) so ​​as to move along the Figure 4 The motor (403) and the disc-shaped substrate (402) rotate in a clockwise direction as indicated by the curved arrow (405) in the figure (as an alternative, counterclockwise rotation can be envisioned), thereby rotating at a high speed. In addition to the drive shaft (404) or as an alternative to the drive shaft (404), other operative couplings between the motor (403) and the disc-shaped substrate (402) can be considered to mechanize the rotation of the disc-shaped substrate (402), such as gears, right-angle mechanical linkages, etc. The excitation light (205a) is the incident light source. When the excitation laser beam (e.g., blue light (205a)) is focused on the phosphor ring (401) to form a light spot, the converted yellow light beam (206) is emitted and combined with the scattered blue light (205b) (as previously described with reference to Figure 2 Said), and will then be collected by a lens system (not shown).

[0040] exist Figure 3 and Figure 4In an embodiment, each substrate (302, 402) is preferably a disk, and the disk optionally has a central opening for coupling with a motor shaft. The disk-shaped substrate can be mechanically balanced using known techniques to ensure minimal friction, wobbling, or other undesirable movement or force during high-speed rotation. The phosphor ring (301, 401) is centered on the disk-shaped substrate (302, 402), that is, the phosphor ring (301, 401) is concentrically arranged on the disk-shaped substrate (302, 402) and is generally positioned at a relatively large radius, that is, the outer edge of the phosphor ring (301, 401) is generally close to the outer edge of the disk-shaped substrate (302, 402). As previously described, light interacting with the corresponding phosphor ring (301, 401) will draw a circular path due to rotation, thereby distributing heat on the circular path. This enables the use of a higher power laser beam, and / or more strongly focusing the beam into a tighter beam spot, thereby increasing the optical power that can be generated.

[0041] exist Figure 3 and Figure 4 In an exemplary phosphor wheel of the invention, the annular light emitting layer (301, 401) includes a phosphor (103, 203) and a light scattering material (104, 203) having a uniform composition arranged in a binder (102, 202) near an annular region in the annular light emitting layer (301, 401). This ensures that the reflected white light (105b, 106) or the transmitted white light (205b, 206) has a uniform spectral composition and uniform whiteness characteristics throughout the 360° rotation range of the disc-shaped substrate (302, 402). This means that the reflected white light (105b, 106) or the transmitted white light (205b, 206) is constant rather than varying over time. Therefore, the rotation of the phosphor wheel driven by the motor (303, 403) is not intended to provide a temporal sequence of different colors as in some conventional phosphor wheels, but rather to provide a heat distribution around the annular region of the heat energy injected by the light source (LD).

[0042] As an alternative, the disclosed Figure 1 and Figure 2 The reflective white light source (100) or the transmissive white light source (200) can be implemented as a static white light source, such as Figure 5 and Figure 6 A static white light source is a white light source in which the luminescent layer is stationary relative to the blue light emitting light source during operation of the white light source, ie, the luminescent layer does not rotate or otherwise move relative to the light source during operation of the white light source.

[0043] Figure 5 A static white light source (500) having a reflective geometry is shown having a Figure 1A substrate (501) of a substrate (101) and a phosphor layer (502) arranged on the substrate (501), the phosphor layer (502) corresponding to Figure 1 The light-emitting layer (102, 103, 104) comprises a binder (102), a yellow phosphor (103), and a light-scattering material including light-scattering particles (104). Figure 1 As described above, the exciting blue light (105a) is focused on the phosphor region (501) to form a light spot, and the converted yellow light beam (106) is emitted and combined with the scattered blue light (105b), as previously described with reference to Figure 1 The will then be collected by a lens system (not shown).

[0044] Figure 6 A static white light source (600) having a light-transmitting geometry is shown, which has a Figure 2 A substrate (601) of a substrate (201) and a phosphor layer (602) arranged on the substrate (601), the phosphor layer (602) corresponding to Figure 2 The light-emitting layer (202, 203, 204) comprises a binder (202), a yellow phosphor (203), and a light-scattering material including light-scattering particles (204). Figure 2 As described above, the exciting blue light (205a) is focused on the phosphor region (601) to form a light spot, and the converted yellow light beam (206) is emitted and combined with the scattered blue light (205b), as previously described with reference to Figure 2 The will then be collected by a lens system (not shown).

[0045] The present invention has been described with reference to the preferred embodiments. Modifications and variations may occur to others upon reading and understanding the above detailed description. The exemplary embodiments should be interpreted as including all modifications and variations that fall within the scope defined by the appended claims and their equivalents.

Claims

1. A fluorescent wheel, include: disc-shaped substrate; as well as a phosphor ring comprising an annular luminescent layer disposed on the disk-shaped substrate, the annular luminescent layer comprising a composition of phosphor and light scattering material disposed in a binder; wherein the composition weight ratio of the components is: 20% to 70% of a binder, 30% to 80% of a phosphor, and 5% to 15% of a light scattering material, so that the generated white light is spectrally uniform in a color temperature range of 4000K to 8000K on an approximately Lambertian distribution, wherein the generated white light includes a combination of converted phosphor emission light converted by the phosphor and unconverted scattered blue light scattered by the light scattering material; and The phosphor wheel is a reflective phosphor wheel including the annular light-emitting layer, and the annular light-emitting layer has a thickness of 0.05 mm to 0.3 mm, or the phosphor wheel is a transmissive phosphor wheel including the annular light-emitting layer, and the annular light-emitting layer has a thickness of 0.01 mm to 0.2 mm.

2. The phosphor wheel according to claim 1, in, The light scattering material includes light scattering particles disposed in the binder.

3. The phosphor wheel according to claim 2, in, The light scattering particles have at least one of the following: sizes ranging from 0.1 to 50 microns, and Over 92% reflectivity for blue light.

4. The phosphor wheel according to any one of claims 1 to 2, in, The light scattering material has at least one of the following: (i) thermal conductivity of 20 W / m·K or more, and (ii) A thermal expansion coefficient and density similar to those of the phosphor.

5. The phosphor wheel according to any one of claims 2 to 3, in, The light scattering particles include one or more of aluminum oxide particles, titanium dioxide particles, magnesium oxide particles, boron nitride particles, aluminum nitride particles, and aluminate particles.

6. The phosphor wheel according to any one of claims 1 to 3, in, The annular light emitting layer includes the phosphor and the light scattering material having uniform composition arranged in the binder near an annular region in the annular light emitting layer.

7. The phosphor wheel according to any one of claims 1 to 3, further comprising: include: A motor is operably connected to rotate the disc-shaped substrate.

8. A white light source, include: The phosphor wheel according to any one of claims 1 to 7; as well as a blue light source arranged to illuminate the phosphor ring with blue light; Wherein, the white light source outputs white light, the white light has a uniform spectrum in an approximately Lambertian distribution within a color temperature range of 4000K to 8000K, and the white light includes converted phosphor emission light from the phosphor irradiated by the blue light, and unconverted scattered blue light scattered by the light scattering material.

9. The white light source according to claim 8, in, The unconverted scattered blue light has a spatial distribution that matches the spatial distribution of the converted phosphor emitted light.

10. The white light source according to any one of claims 8 to 9, in, The unconverted scattered blue light has a diffuse reflective surface spatial distribution, and the converted phosphor emission light has a diffuse reflective surface spatial distribution.

11. The white light source according to any one of claims 8 to 9, in, The blue light has a wavelength in the range of 400 nm to 500 nm.

12. The white light source according to any one of claims 8 to 9, in, The phosphor includes a mixture of a red phosphor that produces converted phosphor emission light in a red light spectrum ranging from 600 to 650 nm and a green phosphor that produces converted phosphor emission light in a green light spectrum ranging from 490 to 560 nm.

13. The white light source according to any one of claims 8 to 9, in, The phosphor wheel is the reflective phosphor wheel, and the disk-shaped substrate is a reflective substrate having a thickness of 0.3 mm to 3 mm and a reflectivity of at least 90%.

14. The white light source according to any one of claims 8 to 9, in, The phosphor wheel is a transmissive phosphor wheel, and the disc-shaped substrate is a light-transmitting substrate having a thickness of 0.1 mm to 3 mm and a transmittance of at least 80% for generated white light.

15. A white light source, include: A light emitting layer comprising a composition of a phosphor and a light scattering material arranged in a binder, wherein the composition weight ratio of the composition is: 20% to 70% of the binder, 30% to 80% of the phosphor, and 5% to 15% of the light scattering material; as well as a light source arranged to illuminate the light-emitting layer with blue light, the blue light having a wavelength in the range of 400 nm to 500 nm; wherein the white light source is configured to operate in a reflective mode and includes the light emitting layer, and the light emitting layer has a thickness of 0.05 mm to 0.3 mm, or wherein the white light source is configured to operate in a transmissive mode and includes the light emitting layer, and the light emitting layer has a thickness of 0.01 mm to 0.2 mm; and Wherein, the white light source outputs white light, and the white light has a uniform spectrum in an approximately Lambertian distribution within a color temperature range of 4000K to 8000K, including converted phosphor emission light from the phosphor illuminated by the blue light, and unconverted scattered blue light scattered by the light scattering material.

16. The white light source according to claim 15, in, The white light source is a static white light source in which the luminescent layer is stationary relative to the light source during operation of the white light source.

17. The white light source according to any one of claims 15 to 16, in, The light scattering material includes light scattering particles disposed in the binder.

18. The white light source according to claim 17, in, The light scattering particles have at least one of the following: sizes ranging from 0.1 to 50 microns, and Over 92% reflectivity for blue light.

19. The white light source according to any one of claims 15 to 16, in, The light scattering material has at least one of the following: (i) thermal conductivity of 20 W / m·K or more, and (ii) A thermal expansion coefficient and density similar to those of the phosphor.

20. The white light source according to claim 17, in, The light scattering particles include one or more of aluminum oxide particles, titanium dioxide particles, magnesium oxide particles, boron nitride particles, aluminum nitride particles, and aluminate particles.

21. The white light source according to any one of claims 15 to 16, in, The unconverted scattered blue light has a spatial distribution that matches the spatial distribution of the converted phosphor emitted light.

22. The white light source according to any one of claims 15 to 16, in, The unconverted scattered blue light has a diffuse reflective surface spatial distribution, and the converted phosphor emission light has a diffuse reflective surface spatial distribution.

23. The white light source according to any one of claims 15 to 16, in, The white light source operates in a reflective mode and comprises a reflective substrate on which the light emitting layer is arranged, the reflective substrate having a thickness of 0.3 mm to 3 mm, or The white light source is operated in a transmission mode and comprises a light-transmitting substrate on which the light-emitting layer is arranged, and the light-transmitting substrate has a thickness of 0.1 mm to 3 mm.

24. The white light source according to any one of claims 15 to 16, in, The converted phosphor emits light comprising a mixture of red light and green light, the red light being within a spectrum ranging from 600 to 650 nm and the green light being within a spectrum ranging from 490 to 560 nm, the red light being emitted by the red phosphor and the green light being emitted by the green phosphor in response to being illuminated by the blue light.

25. The white light source according to any one of claims 15 to 16, in, The blue light is provided by a laser diode or an LED, which provides blue light having a wavelength range of 400 nm to 480 nm.

26. A method for generating white light, include: converting a portion of the blue light into phosphor light by a phosphor in a composition arranged in the light emitting layer, wherein the composition weight ratio of the composition is: 20% to 70% of a binder, 30% to 80% of a phosphor, and 5% to 15% of a light scattering material; scattering a portion of the blue light that is not converted into phosphor-emitted light by scattering particles arranged in the light-emitting layer to generate scattered blue light; as well as Output white light, the white light is spectrally uniform in an approximately Lambertian distribution within a color temperature range of 4000K to 8000K, including a combination of the phosphor emission light and the scattered blue light, wherein the light-emitting layer has a thickness of 0.05mm to 0.3mm to output white light, and the white light is reflected white light, or wherein the light-emitting layer has a thickness of 0.01mm to 0.2mm to output white light, and the white light is transmitted white light.

27. The method for generating white light according to claim 26, in, The phosphor emits light having a diffuse reflective surface spatial distribution, and the scattered blue light has a diffuse reflective surface spatial distribution.

28. The method for generating white light according to any one of claims 26 to 27, further comprising: include: Simultaneously with the converting, scattering and outputting, a phosphor wheel is rotated, the phosphor wheel comprising a disk-shaped substrate on which the light-emitting layer is arranged as a phosphor ring.

29. The method for generating white light according to claim 28, in, The phosphor wheel is a reflective phosphor wheel, and the reflected white light is output on the same side of the phosphor wheel as the side illuminated by the blue light.

30. The method for generating white light according to claim 28, in, The phosphor wheel is a transmissive phosphor wheel, and the transmitted white light is output on a side of the phosphor wheel opposite to a side illuminated by the blue light.

31. The method for generating white light according to any one of claims 26 to 27, in, The phosphor includes a mixture of a red phosphor and a green phosphor, wherein the phosphor emission light of the red phosphor is red light in a spectrum ranging from 600 to 650 nm, and the phosphor emission light of the green phosphor is green light in a spectrum ranging from 490 to 560 nm.

Images