TWI544179B - Wavelength-converting device and illumination system using same - Google Patents

Description

Optical wavelength conversion device and its suitable light source system

The present invention relates to a light wavelength conversion device, and more particularly to a light wavelength conversion device and a light source system therefor.

The optical wavelength conversion device is an optical transducing element mainly used for converting a wavelength of light to generate a specific visible light wavelength as a light source, and is generally applied to special illumination, such as a spotlight, a headlight, a display light source or a projector image.

In general, the conventional light wavelength conversion device is a large-scale fluorescent pink wheel, and is intended to cooperate with a laser light source and convert the laser light into color light having different wavelengths. Under high-power operation, the wavelength conversion efficiency of the fluorescent pink wheel can greatly enhance the photoelectric conversion and lumen output of the projector. In recent years, it has become an important source of new generation projection technology.

Please refer to Fig. 1, which is a cross-sectional view showing the structure of a conventional fluorescent pink wheel. As shown in FIG. 1, the conventional fluorescent pink wheel 1 is mainly a three-layer structure having a substrate 10, a reflective layer 11, and a fluorescent layer 12. The reflective layer 11 is formed on the substrate 10 , and the fluorescent layer 12 is formed on the reflective layer 11 , that is, the reflective layer 11 is formed between the substrate 10 and the fluorescent layer 12 . After the first band of light L1 excites the phosphor powder 121 of the phosphor layer 12 and is converted into the second band of light L2, the second band of light L2 is subjected to full-angle scattering, wherein when defined by the fluorescent layer 12 away from the reflective layer When the direction of 11 is positive, reverse scatter, also That is, the scattering from the direction in which the fluorescent layer 12 is directed to the reflective layer 11 is reflected by the reflective layer 11 and then forwardly scattered. It should be noted that the forward direction referred to herein is the fluorescent layer 12 away from the reflective layer 11 The direction is forward; for the same reason, the reverse direction refers to the direction in which the phosphor layer 12 faces the reflective layer 11 in the reverse direction. Since the second-band light L2 converted by the phosphor powder belongs to the Lambertian light-emitting model, the reflective layer 11 must have the ability to reflect visible light of 400 nm to 700 nm, and also needs to have a higher reflection. The ability to incident light at 70 degrees, but for multilayer mirror technology, it is a difficult task to cope with such a wide reflection band and angle of incidence.

In addition, considering the Brewster Angle (θ _B =tan ^-1 (n ₂ /n ₁ )) effect of the refractive index of the incident environment n ₁ and the penetrating environment n ₂ , when the incident angle of the incident light is greater than or When it is equal to the Brewster angle, the P-polarized light of the incident light will penetrate the reflective layer 11 in its entirety, so that the reflectance of the reflective layer 11 is greatly reduced, and light leakage occurs. For example, when the incident light is incident from the effective refractive index n value of about 1.4 to 1.5 to the air having the refractive index n value of 1, the Brewster angle is 35.5 degrees, and another critical angle (Critical Angle, θ _{C )} = sin ^-1 (n ₂ /n ₁ )) is 45.6 degrees, that is, when the incident angle of incident light is greater than or equal to 35.5 degrees, the P-polarized light of the incident light will penetrate all the way, resulting in light leakage until When the incident angle is greater than 45.6 degrees, the incident light will be totally reflected by the critical angle. It can be inferred that in the structure of the conventional fluorescent pink wheel 1, the reflective layer 11 is under the structure of the fluorescent layer 12 (n ₁ ~ 1.4-1.5) and the substrate 10 (n _s ), and its Brewster angle system Less than the critical angle, so when the incident light angle is greater than or equal to the Brewster angle and less than the critical angle, in view of the fact that the multilayer mirror technology cannot contain full spectrum and large angle reflection, there will be a large amount of incident light loss that cannot be reflected and applied. In the light path, a large amount of energy is wasted, and the manufacturing difficulty of the optical wavelength conversion device and the light source system is greatly increased.

Therefore, it is necessary to develop an optical wavelength conversion device and a light source system therefor to improve the above-mentioned shortcomings and problems, thereby enhancing its industrial applicability.

The main object of the present invention is to provide an optical wavelength conversion device and a light source system therefor, which solve and improve the problems and disadvantages of the aforementioned prior art.

Another object of the present invention is to provide an optical wavelength conversion device and a light source system therefor, which are selected by the optical wavelength conversion device and satisfy θ _C =sin ^-1 (n _amb /n _s ) and n _r > 2(n _amb ² )/n _s two equations to achieve an angle that causes the Brewster angle θ _{B to} be greater than the critical angle θ _C and utilizes the total reflection of the critical angle to mitigate the large-angle incident design of the multilayer mirror technique. Effectively avoids the waste of energy, and at the same time simplifies the manufacturing of the optical wavelength conversion device and the light source system and the difficulty of material selection.

In order to achieve the above object, a wider aspect of the present invention provides a light wavelength conversion device suitable for converting a first wavelength band, comprising: a transmissive substrate having a refractive index n _s value, wherein the refractive index The n _s value is greater than a refractive index n _amb value of the environmental medium; a phosphor layer disposed on one side of the transmissive substrate for converting the first band of light into a second band of light; and an optical a layer opposite to the phosphor layer disposed on the other side of the transmissive substrate for reflecting the second wavelength band, wherein the optical layer has an effective refractive index n _r value; wherein the refractive index n _s value, The refractive index n _amb value and the effective refractive index n _r value satisfy a relationship of n _r > 2 (n _amb ² ) / n _s .

In some embodiments, the transmissive substrate is configured to penetrate the first band of light and the second band of light.

In some embodiments, the optical layer is configured to penetrate the first band of light and reflect the second band of light. The first band light system is a blue light or a UV light source, and the second band light system is visible light having a wavelength greater than 460 nm.

In some embodiments, the optical layer is configured to reflect the first band of light and the second band of light.

In some embodiments, the transmissive substrate is a sapphire substrate, a glass substrate, a boron germanium glass substrate, a float boron germanium glass substrate, a fused quartz substrate, or a calcium fluoride substrate.

In some embodiments, the optical layer comprises at least one metallic material, and the metallic material is silver or aluminum, or at least comprises a silver alloy or an aluminum alloy.

In some embodiments, the optical layer comprises a distributed Bragg reflector or an omnidirectional reflector.

In order to achieve the above object, another broad aspect of the present invention provides a light source system comprising: a solid state light emitting device configured to emit a first band of light to a light path; and a light wavelength conversion device disposed at the The light path includes: a transmissive substrate having a refractive index n _s value, wherein the refractive index n _s value is greater than a refractive index n _amb value of the environmental medium; a fluorescent layer disposed on the transparent a side of the substrate for converting the first band of light into a second band of light and outputting the second band of light; and an optical layer disposed opposite to the other side of the transmissive substrate For reflecting the second wavelength band, wherein the optical layer has an effective refractive index n _r value; wherein the refractive index n _s value, the refractive index n _amb value, and the effective refractive index n _r value satisfy n _r > The relational expression of 2(n _amb ² )/n _s .

In some embodiments, the optical wavelength conversion device is a reflective optical wavelength conversion device. The solid state light emitting device is disposed adjacent to the phosphor layer.

In some embodiments, the optical wavelength conversion device is a transmissive optical wavelength conversion device. Wherein, the solid state light emitting element is adjacent to the optical layer.

1‧‧‧Traditional light wavelength conversion device

10‧‧‧Substrate

11‧‧‧reflective layer

12‧‧‧Fluorescent layer

121‧‧‧Fluorescent powder

2‧‧‧Light wavelength conversion device

20‧‧‧Transmissive substrate

21‧‧‧Optical layer

22‧‧‧Fluorescent layer

3‧‧‧Light source system

31‧‧‧Solid light-emitting elements

A‧‧‧Environmental medium

I‧‧‧ incident light

L1‧‧‧ first band light

L2‧‧‧second band light

P‧‧‧Light path

Figure 1 is a cross-sectional view showing the structure of a conventional fluorescent pink wheel.

Figure 2 is a schematic view showing incident light incident on an optical layer from a substrate of the optical wavelength conversion device of the preferred embodiment of the present invention and reflected.

Fig. 3 is a graph showing the reflectance-incident angle of a incident light incident on the air from the light wavelength conversion device of the present invention.

Figure 4A is a block diagram showing the light source system of the preferred embodiment of the present invention.

Figure 4B is a block diagram showing the light source system of another preferred embodiment of the present invention.

Fig. 5 is a cross-sectional view showing the structure of a reflection type optical wavelength conversion device according to an embodiment of the present invention.

Fig. 6 is a view showing a reflection spectrum of the reflection type optical wavelength conversion device shown in Fig. 5.

Figure 7 is a cross-sectional view showing the structure of a transmissive optical wavelength conversion device according to an embodiment of the present invention.

Fig. 8 is a view showing the penetration spectrum of the transmissive optical wavelength conversion device shown in Fig. 7.

Some exemplary embodiments embodying the features and advantages of the present invention are described in detail in the following description. It is to be understood that the present invention is capable of various modifications in various aspects, and is not to be construed as a limitation.

Please refer to FIG. 2, which is a schematic diagram showing incident light incident on an optical layer from a substrate of the optical wavelength conversion device of the preferred embodiment of the present invention and reflected. As shown in FIG. 2, the present invention proposes a light wavelength conversion device 2 for plating an optical layer 21 under the substrate 20 such that the substrate 20 is interposed between the phosphor layer 22 and the optical layer 21 under the optical structure. The incident light is incident on the optical layer 21 from the substrate 20. Specifically, the incident light I is incident on the optical layer 21 from the transmissive substrate 20 and is reflected by the interface between the optical layer 21 and the environmental medium A, wherein the critical angle θ _C is the refractive index n _amb of the environmental medium A. The inverse sine function of the quotient obtained by dividing the refractive index n _s of the transmissive substrate 20, that is, θ _C = sin ^-1 (n _amb /n _s ); the Brewster angle θ _B is the effective refractive index of the optical layer 21 The inverse tangent function of the quotient obtained by dividing the value of n _r by the refractive index n _s of the transmissive substrate 20 is θ _B =tan ^-1 (n _r /n _s ). By the critical angle created by the substrate n _s and the environmental medium A, the optical layer 21 only needs to consider the full-wavelength spectral reflection (400-700 nm) of the incident angle below the critical angle, and the design is easy to satisfy the Brewster angle θ _B The angle is greater than the angle of the critical angle θ _C ; further calculation can be used to derive the relationship between the refractive index n _s value of the transmissive substrate 20, the effective refractive index n _{r of the} optical layer 21, and the refractive index n _{amb of the} environmental medium A. The formula is: n _r >2(n _amb ² )/n _s . In other words, if the material and structure selected by the optical wavelength conversion device of the present invention satisfy θ _C = sin ^-1 (n _amb /n _s ) and n _r >2(n _amb ² )/n _s , the optical wavelength conversion device The angle at which the Brewster angle θ _B is greater than the critical angle θ _C can be achieved and the loss of incident light can be further reduced.

Please refer to FIG. 3, which is a graph showing the reflectance-incident angle angle of incident light incident on a sapphire substrate. As shown in FIG. 3, in order to solve the problem of incident light loss of the optical wavelength conversion device in the prior art, the present invention considers the refractive index n value of the optical wavelength conversion device and the air, and realizes that the Brewster angle is greater than the critical angle. The angle. In the optical wavelength conversion device, the angle of the Brewster angle depends on the effective refractive index n _r of the optical layer of the overall optical wavelength conversion device, and the angle of the critical angle depends on the substrate n _s of the optical wavelength conversion device and the environment n _amb Refractive index. Therefore, if a substrate having a large refractive index n _s value, such as a sapphire substrate, has a refractive index n _s value of about 1.77, the critical angle angle can be lowered to 34.4 degrees, that is, as shown in FIG. Further, by inverse operation, the maximum value of the effective refractive index n _r of the optical layer of the overall optical wavelength conversion device can be further known.

For example, the angle of the effective refractive index n _r of the optical layer of the overall optical wavelength conversion device is less than 1.45, but not limited thereto. In addition, from the definition of Brewster's angle θ _B =tan ^-1 (n ₂ /n ₁ ), it can be found that the angle of the Brewster angle is raised, and it is necessary to lower the value of the refractive index n ₁ in the arctangent function. Therefore, the structure of the optical wavelength conversion device 2 of the foregoing preferred embodiment is proposed in the present invention to achieve the object of the invention that the angle of the Brewster angle is greater than the angle of the critical angle, and further avoiding waste of energy while simplifying the wavelength of light. The difficulty of manufacturing and material selection of the conversion device and the light source system.

In contrast, the conventional technology, under the framework of the traditional optical wavelength conversion device, the refractive index n ₁ value is limited by the colloidal properties of the fluorescent layer, generally more than 1.4-1.5 of the rubber material, the material is difficult to adjust, obviously unable to The object of the invention is achieved.

Please refer to FIG. 4A and FIG. 4B and FIG. 2 , wherein FIG. 4A is a structural diagram of a light source system according to a preferred embodiment of the present invention, and FIG. 4B is a diagram showing a light source system according to another preferred embodiment of the present invention. Architecture diagram. As shown in FIG. 2, FIG. 4A and FIG. 4B, the optical wavelength conversion device 2 of the present invention is suitable for converting the first-band light L1 emitted from the solid-state light-emitting element 31 of the light source system 3, and the optical wavelength conversion device 2 includes The transparent substrate 20, the optical layer 21, and the fluorescent layer 22. The transmissive substrate 20 can be, for example, a sapphire substrate, a glass substrate, a boron borosilicate glass substrate, a float borax glass substrate, or a fused quartz. a substrate or a calcium fluoride (CaF ₂ ) substrate or the like, but not limited thereto, and having a refractive index n _s value, wherein the refractive index n _s value is greater than a refractive index n _amb value of one of the environmental media. The phosphor layer 21 is disposed on one side of the transmissive substrate 20 for converting the first band light L1 into the second band light L2. The optical layer 22 may comprise at least one metal material such as, but not limited to, silver or aluminum or an alloy containing at least one of the metal components, and may also include a Distributed Bragg Reflector (DBR) or an omnidirectional reflective layer (Omni). Directional Reflector (ODR), wherein the number of layers of the Bragg reflection layer and the omnidirectional reflection layer can be selected according to actual needs, for example, the light wavelength conversion device is a reflective or transmissive structure, and preferably has a plurality of layers. The optical layer 21 is disposed on the other side of the transmissive substrate 20 opposite to the phosphor layer 22 for reflecting the second wavelength band light L2, and the optical layer 21 has an effective refractive index n _r value. . Wherein, in order to satisfy the present case, the angle of the Brewster angle θ _B is greater than the angle of the critical angle θ _C to further reduce the energy loss, and the refractive index n _s value, the refractive index n _amb value and the effective refractive index n _r are satisfied. The relationship between n _r >2(n _amb ² )/n _s . Thereby, the waste of energy can be effectively avoided, and the difficulty of manufacturing and material selection of the optical wavelength conversion device and the light source system can be simplified.

Please refer to FIG. 5 and FIG. 2 and FIG. 4A. FIG. 5 is a cross-sectional view showing the structure of the reflective optical wavelength conversion device according to an embodiment of the present invention. As shown in FIG. 2, FIG. 4A and FIG. 5, the optical wavelength conversion device 2 of the light source system 3 of the present invention can be a reflective optical wavelength conversion device, wherein the solid-state light-emitting element 31 is adjacent to the fluorescent layer 22, The structure is such that the incident direction of the first band light L1 is substantially opposite to the final exit direction of the second band light L2. In some embodiments, the transmissive substrate 20 is configured to penetrate the first band light L1 and the second band light L2, and the optical layer 21 is configured to reflect the first band. The light L1 and the second band light L2, that is, the visible light having a wavelength of 400 nm to 700 nm.

Please refer to Fig. 6 and Fig. 5, wherein Fig. 6 shows the reflection spectrum of the reflective optical wavelength conversion device shown in Fig. 5. As shown in FIG. 5 and FIG. 6, when the sapphire substrate is selected as the transmissive substrate 20 of the reflective light wavelength conversion device of the present invention, the critical angle θ _C is only 34.4 degrees, and the optical layer is easily designed to realize the Brewster angle. The angle of θ _B is greater than the angle of the critical angle θ _C. The reflection spectrum of the reflective light wavelength conversion device 2 of the present invention shows the reflectance of visible light of 400 nm to 700 nm at an incident angle of 0 and 30 degrees. In essence, it is about 100%, and the incident light higher than 34.4 degrees is almost full-spectrum and full-angle reflection by the total reflection of the critical angle. Therefore, in the reflection spectrum shown in Fig. 6, The visible light of 400 nm to 700 nm is omitted in the portion where the incident angle is greater than 30 degrees.

Referring to FIG. 7 and FIG. 2 and FIG. 4B, FIG. 7 is a cross-sectional view showing the structure of the transmissive optical wavelength conversion device according to an embodiment of the present invention. As shown in FIG. 2, FIG. 4B and FIG. 7, the optical wavelength conversion device 2 of the light source system 3 of the present invention can be a transmissive optical wavelength conversion device, and the solid-state light-emitting element 31 is disposed adjacent to the optical layer 21 to The arrangement is such that the incident direction of the first band light L1 is substantially the same as the final exit direction of the second band light L2. In some embodiments, the transmissive substrate 20 is configured to penetrate the first band light L1 and the second band light L2, and the optical layer 21 is configured to penetrate the first band light L1 and reflect the second band. The light L2, wherein the first band light L1 is blue light, and the second band light L2 is visible light having a wavelength greater than 460 nm, which is not limited thereto.

Please refer to Fig. 8 and Fig. 7, wherein Fig. 8 shows the penetration spectrum of the transmissive optical wavelength conversion device shown in Fig. 7. As shown in FIGS. 7 and 8, when a sapphire substrate is selected as the transmissive substrate 20 of the transmissive optical wavelength conversion device of the present invention, and the angle at which the Brewster angle θ _B is greater than the critical angle θ _C is achieved. At the target, the penetration spectrum of the optical wavelength conversion device 2 of the present invention shows the second wavelength light L2, that is, the visible light having a wavelength greater than 460 nm, and the transmittance is substantially 0% when the incident angle is 0 degrees. That is, almost total reflection is achieved. In addition, it is also shown in FIG. 8 that the first wavelength band light L1 in this embodiment, that is, the blue light having a wavelength less than or equal to 460 nm, has substantially the same transmittance when the incident angle is 0 degrees. 100%, that is, almost full penetration, thereby verifying that the optical layer 21 is indeed structured to penetrate the first wavelength band light L1 and reflect the second band light L2.

In summary, the present invention provides an optical wavelength conversion device and a light source system therefor, which solve and improve the problems and disadvantages of the prior art. Specifically, the present invention provides an optical wavelength conversion device and a light source system therefor, wherein the material and structure selected by the optical wavelength conversion device satisfy θ _C =sin ^-1 (n _amb /n _s ) and n _r >2 ( n _amb ² ) / n _s two, in order to achieve the angle of the Brewster angle θ _B is greater than the critical angle θ _C , can effectively avoid energy waste, while simplifying the manufacture and material selection of the optical wavelength conversion device and the light source system The difficulty and other effects.

The present invention has been described in detail by the above-described embodiments, and may be modified by those skilled in the art, without departing from the scope of the appended claims.

2‧‧‧Light wavelength conversion device

20‧‧‧Transmissive substrate

21‧‧‧Optical layer

22‧‧‧Fluorescent layer

Claims (11)

An optical wavelength conversion device, configured to convert a first wavelength band of light, comprising: a transmissive substrate having a refractive index n _s value, wherein the refractive index n _s value is greater than a refractive index n _amb value of one of the environmental media; a phosphor layer disposed on one side of the transmissive substrate for converting the first wavelength band light into a second band of light; and an optical layer disposed on the transmissive substrate opposite to the phosphor layer The other side is configured to reflect the second wavelength band, wherein the optical layer has an effective refractive index n _r value; wherein the first wavelength light system enters the optical wavelength conversion device by the fluorescent layer, or the first a band light system enters the light wavelength conversion device by the optical layer, and the refractive index n _s value, the refractive index n _amb value, and the effective refractive index n _r value satisfy n _r >2(n _amb ² )/n _s The relationship. The optical wavelength conversion device of claim 1, wherein the optical layer is configured to penetrate the first wavelength band and reflect the second wavelength band. The optical wavelength conversion device of claim 2, wherein the first wavelength light system is a blue light or a UV light source, and the second wavelength light system is visible light having a wavelength greater than 460 nm. The optical wavelength conversion device of claim 1, wherein the optical layer is configured to reflect the first band of light and the second band of light. The optical wavelength conversion device according to claim 1, wherein the transmissive substrate is a sapphire substrate, a glass substrate, a boron germanium glass substrate, a float boron germanium glass substrate, a fused quartz substrate or a calcium fluoride substrate. . The optical wavelength conversion device of claim 1, wherein the optical layer comprises at least one metal material, and the metal material is silver or aluminum. The optical wavelength conversion device of claim 1, wherein the optical layer comprises a silver alloy or an aluminum alloy. The optical wavelength conversion device of claim 1, wherein the optical layer comprises a distributed Bragg reflection layer or an omnidirectional reflection layer. A light source system comprising: a solid state light emitting device configured to emit a first wavelength band of light to a light path; and a light wavelength conversion device disposed on the light path, comprising: a transmissive substrate having a refractive index a value of n _s , wherein the value of the refractive index n _s is greater than a refractive index n _{amb of the} environmental medium; a phosphor layer disposed on one side of the transmissive substrate for converting the first band of light into one a second band of light and outputting the second band of light; and an optical layer disposed on the other side of the transmissive substrate opposite to the reflective substrate for reflecting the second band of light, wherein the optical layer has an effective a refractive index n _r value; wherein the solid state light emitting device is disposed adjacent to the fluorescent layer, or the solid state light emitting device is adjacent to the optical layer, and the refractive index n _s value, the refractive index n _amb value, and the The effective refractive index n _r value satisfies the relationship of n _r > 2 (n _amb ² ) / n _s . The light source system of claim 9, wherein the optical wavelength conversion device is a reflective optical wavelength conversion device. The light source system of claim 9, wherein the optical wavelength conversion device is a transmissive optical wavelength conversion device.