Wavelength conversion element and projection device

A wavelength conversion element includes a substrate, a counterweight member and a wavelength conversion layer. The substrate has a first surface and a second surface opposite to each other. The counterweight member is welded to the first surface of the substrate and protrudes from the first surface of the substrate. The wavelength conversion layer is disposed on the first surface or the second surface of the substrate. A projection device having the wavelength conversion element is also provided. The wavelength conversion element and the projection device provided by the invention have good reliability.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application CN202010875063.7, filed on Aug. 27, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

FIELD OF THE INVENTION

The invention relates to a wavelength conversion element, and more particularly to a wavelength conversion element used for a projection device, and a projection device having the wavelength conversion element.

BACKGROUND OF THE INVENTION

The rotation speed of the phosphor wheel of the laser projector in prior art is about 7200 rpm or higher. Under such high-speed operation, a slight imbalance may cause a large vibration, and the quality of dynamic balance has a significant impact on the service life of a motor.

The dynamic balance can be improved by weighting method. Specifically, the phosphor wheel may be provided with a counterweight block, and the counterweight block can be fixed on the phosphor wheel by adhesive material (e.g., light curing adhesive). However, since the poor temperature resistance of the adhesive material, the adhesive material is likely to overheat and deteriorate and lose its viscosity as the power specifications of the projector increase, causing the counterweight block cannot be firmly attached to the phosphor wheel. In addition, part of the adhesive material will vaporize into gas and adhere to other components when the adhesive material is in a high temperature environment for a long time, and therefore not only other components may be contaminated, but the quality of the adhesive material may gradually decrease due to gasification, and eventually leading to imbalance in dynamic balance. In addition, the counterweight block is usually disposed close to the center of the phosphor wheel and away from the high temperature area on the outer edge of the phosphor wheel, resulting in a small rotation radius of the counterweight block, so the unit weight of the counterweight block has low balance benefits. In other words, a heavier counterweight block is required to achieve dynamic balance, and the amount of adhesive material used to fix the counterweight block also increases, and the weight load on the motor also increases.

The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The invention provides a wavelength conversion element with better reliability.

The invention provides a projection device with better reliability.

Other objectives and advantages of the invention can be further illustrated by the technical features broadly embodied and described as follows.

In order to achieve one or a part or all of the above or other objectives, an embodiment of the invention provides a wavelength conversion element, which includes a substrate, a counterweight member and a wavelength conversion layer. The substrate has a first surface and a second surface opposite to each other. The counterweight member is welded to the first surface of the substrate and protrudes from the first surface of the substrate. The wavelength conversion layer is disposed on the first surface or the second surface of the substrate.

In order to achieve one or a part or all of the above or other objectives, an embodiment of the invention provides a projection device, which includes an illumination system, a light valve and a projection lens. The illumination system is adapted to provide an illumination beam. The light valve is disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam. The projection lens is disposed on a transmission path of the image beam. The illumination system includes an excitation light source and the aforementioned wavelength conversion element. The excitation light source is adapted to provide an excitation beam. The wavelength conversion element is disposed on a transmission path of the excitation beam.

In summary, because the invention adopts the wavelength conversion element in which the counterweight member is welded to the substrate, it is not necessary to use the adhesive material with poor temperature resistance to fix the counterweight member, so that the wavelength conversion element of the invention has better reliability. On the other hand, the projection device of the invention can also have better reliability due to adopting the above-mentioned wavelength conversion element.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.1Ais a schematic top view of a wavelength conversion element according to an embodiment of the invention.FIG.1Bis a schematic cross-sectional view of the wavelength conversion element, taken along the line A-A inFIG.1A. Please refer toFIGS.1A and1B. The wavelength conversion element100aincludes a substrate110, a counterweight member120and a wavelength conversion layer130. The substrate110has a first surface111and a second surface112opposite to each other. The counterweight member120is welded to the first surface111of the substrate110and protrudes from the first surface111. The wavelength conversion layer130is disposed on the first surface111or the second surface112of the substrate110. In this embodiment, the wavelength conversion layer130is disposed on the first surface111of the substrate110as an example.

In some embodiments, the wavelength conversion element100amay further include a motor140and a fixing member150. The substrate110is sleeved on the rotating shaft141of the motor140. The fixing member150is sleeved on the rotating shaft141and pressed against the substrate110. The wavelength conversion layer130surrounds the rotating shaft141. The counterweight member120is disposed between the fixing member150and the outer edge113of the substrate110. The counterweight member120of this embodiment, for example, does not contact the fixing member150or the wavelength conversion layer130. However, in another embodiment, the counterweight member120may contact the fixing member150, and the counterweight member120may be welded to the fixing member150and the substrate110. In addition, the counterweight member120may also contact the wavelength conversion layer130. The embodiment does not limit the position of the counterweight member120on the substrate110.

In some embodiments, the material of the substrate110may include metal (e.g., aluminum, copper, silver) or other materials with high temperature resistance and high thermal conductivity (e.g., ceramic), but the invention is not limited thereto. In this embodiment, the shape of the substrate110may be a ring, but is not limited thereto.

In some embodiments, the wavelength conversion layer130is used to convert an excitation beam into a converted beam. The wavelength conversion layer130may include at least one wavelength conversion material. For example, the wavelength conversion layer130may include a wavelength conversion material for emitting yellow or green beams, but is not limited thereto. In addition, the wavelength conversion material is, for example, a fluorescent material, a phosphorescent material (e.g., a phosphor), or a nano material (e.g., a quantum dot), but is not limited thereto.

In some embodiments, the material of the counterweight member120may include metal or plastic, where the metal is, for example, copper, but is not limited thereto. In addition, the counterweight member120of this embodiment is, for example, directly welded to the substrate110. In other embodiments, the counterweight member120may also be welded to the substrate110by other materials, and the material for welding the counterweight member120to the substrate110and the material of the counterweight member120may be the same or different from each other. For example, the material for welding the counterweight member120to the substrate110may include metal, ceramic, glass, plastic, etc., and the invention is not limited thereto.

In some embodiments, the counterweight member120and the substrate110are partially melted to form a welding structure W. As shown inFIG.1B, the welding structure W extends from the connection between the counterweight member120and the substrate110to at least one of the second surface112of the substrate110and the surface121of the counterweight member120away from the substrate110. The welding structure W may further protrude from the surface121of the counterweight member120away from the substrate110and/or the second surface112of the substrate110. As shown inFIG.1B, the two opposite ends of the welding structure W protrude from the second surface112of the substrate110and the surface121of the counterweight member120, respectively. In another embodiment, the end of the welding structure W may only protrude from the second surface112of the substrate110or the surface121of the counterweight member120. Alternatively, the end of the welding structure W, for example, extends to but does not protrude from the second surface112of the substrate110or the surface121of the counterweight member120.

In some embodiments, single-point welding, multi-point welding, linear welding or surface welding can be used to match the shape of the counterweight member120and ensure that the counterweight member120can be firmly welded to the substrate110, but the invention is not limited thereto. In addition, the welding method may be laser welding, electric arc welding, resistance welding, electron beam welding, brazing, friction welding, ultrasonic welding, etc., but the invention is not limited thereto. In this embodiment, a laser welding method is used to irradiate a part of the counterweight member120and the substrate110with a laser to cause melting, and the melted part is then cooled to form the welding structure W. Therefore, the welding structure W extends from the connection between the counterweight member120and the substrate110to at least one of the second surface112of the substrate110and the surface121of the counterweight member120. For example, the welding structure W will extend at least to the surface121of the counterweight member120if the laser is irradiated to the counterweight member120from the surface121of the counterweight member120, but the welding structure W may also extend to the second surface112of the substrate110.

Compared with the prior art, since the counterweight member120of this embodiment is fixed on the substrate110by welding instead of using an adhesive material with poor temperature resistance, it can be ensured that the counterweight member120can be firmly fixed on the substrate110, and therefore the reliability of the wavelength conversion element100ais improved. In addition, the welding method has the advantage of better temperature resistance. That is, the counterweight member120can still be disposed close to the outer edge113of the substrate110even if the temperature of the outer edge113of the substrate110is higher than the temperature of the center of the substrate110. In this way, the counterweight member120can have a greater radius of rotation, so that the balance benefit of the counterweight member120per unit weight can be improved, the total weight of the counterweight member120can be reduced to reduce the cost, and the weight load of the motor140can be reduced. It should be noted that, the counterweight member120may also be welded to the fixing member150in other embodiments of the invention, that is, the counterweight member120is not limited to being welded to the substrate110.

FIG.2is a schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. The wavelength conversion element100bof this embodiment and the above-mentioned wavelength conversion element100ahave similar structures and advantages, and only the differences will be described below. Please refer toFIG.2. The counterweight member120and the wavelength conversion layer130of this embodiment are located on different sides of the substrate110b, and the counterweight member120is located between the fixing member150and the outer edge113of the substrate110b. In the embodiment shown inFIGS.1A and1B, the first surface111of the substrate110faces the light source (not shown), the wavelength conversion layer130is located on the first surface111of the substrate110to receive the excitation beam provided by the light source, and the counterweight member120is also disposed on the first surface111of the substrate110. In the embodiment shown inFIG.2, the second surface112bof the substrate110bfaces the light source, the wavelength conversion layer130is located on the second surface112bof the substrate110b, and the counterweight member120is located on the first surface111bof the substrate110bfacing away from the light source.

In some embodiments, since the counterweight member120and the wavelength conversion layer130are located on different sides of the substrate110b, the counterweight member120may be located under the wavelength conversion layer130. In other words, the orthographic projection of the wavelength conversion layer130on the first surface111bcan overlap the counterweight member120. The counterweight member120of this embodiment can have a greater radius of rotation, which can further improve the balance benefit of the counterweight member120per unit weight.

FIG.3is a partial schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. The wavelength conversion element100cof this embodiment and the above-mentioned wavelength conversion element100ahave similar structures and advantages, and only the differences will be described below. Please refer toFIG.3, the counterweight member120cand the substrate110care partially melted to form a welding structure WC. The welding structure WC is located inside the counterweight member120cand the substrate110c, and is respectively separated from the surface121cof the counterweight member120cand the second surface112cof the substrate110cby a certain distance. Specifically, the welding structure WC of this embodiment is formed by, for example, resistance welding. Before the welding structure WC is formed, a voltage may be applied to the second surface112cof the substrate110cand the surface121cof the counterweight member120c, so that current can flow between the substrate110cand the counterweight member120c. Since the junction between the substrate110cand the counterweight member120chas a relatively large resistance, the current may generate a high temperature when passing through the junction, which causes melting at the junction. The application of voltage can be stopped after the welding occurs at the junction, so that the molten parts of the substrate110cand the counterweight member120ccan be cooled and solidified to form the welding structure WC. The difference from the embodiment ofFIGS.1A and1Bis that since this embodiment starts the welding at the junction between the substrate110cand the counterweight member120c, the welding structure WC does not extend to the second surface112cof the substrate110cand the surface121cof the counterweight member120c, but is separated from the second surface112cof the substrate110cby a distance D1and is separated from the surface121cof the counterweight member120cby a distance D2.

FIG.4is a partial schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. The wavelength conversion element100dof this embodiment and the above-mentioned wavelength conversion element100ahave similar structures and advantages, and only the differences will be described below. In order to enhance the firmness of the welding, the wavelength conversion element100dof this embodiment further includes an auxiliary welding part160d. The auxiliary welding part160dis located around the counterweight member120dand on the first surface111dof the substrate110d, and is welded to the substrate110dand the counterweight member120d. The auxiliary welding part160d, the substrate110dand the counterweight member120dare partially melted to form at least one welding structure WD. The welding structure WD is located between the auxiliary welding part160dand the counterweight member120d, and can extend to the second surface112dof the substrate110d. The auxiliary welding part160dmay be, for example, a material with a melting point that is significantly different from that of the counterweight member120dand the substrate110d. For example, the material of the substrate110dcan be aluminum, the material of the counterweight member120dcan be copper, and the material of the auxiliary welding part160dcan be tin, but the invention is not limited thereto. The welding structure WD can be formed by any of the aforementioned welding methods. Taking laser welding as an example, before the welding structure WD is formed, the junction between the auxiliary welding part160dand the counterweight member120dis irradiated with a laser to partially melt the auxiliary welding part160d, the counterweight member120dand the substrate110d. The welding structure WD is formed after the melted part is cooled and solidified. In some embodiments, the material of the auxiliary welding part160dmay include phosphor bronze alloy, silver alloy, gold, palladium alloy, aluminum alloy, copper alloy, and nickel alloy.

FIG.5is a partial schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. Please refer toFIG.5. The auxiliary welding part160eof this embodiment is, for example, sandwiched between the counterweight member120eand the first surface111eof the substrate110eand is welded to the substrate110eand the counterweight member120e. The auxiliary welding part160e, the substrate110eand the counterweight member120eare partially melted to form a welding structure WE. The welding structure WE penetrates the counterweight member120e, the auxiliary welding part160eand the substrate110e. The welding structure WE of this embodiment can be formed by any of the foregoing welding methods, and no redundant detail is to be given herein.

FIG.6is a partial schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. The wavelength conversion element100fof this embodiment and the above-mentioned wavelength conversion element100ahave similar structures and advantages, and only the differences will be described below. As shown inFIG.6, the wavelength conversion element100ffurther includes a welding part170f. The welding part170fis melted and connected between the counterweight member120fand the first surface111fof the substrate110f. In other words, the wavelength conversion element100fof this embodiment connects the counterweight member120fand the substrate110fwith the welding part170fafter melting, wherein the counterweight member120fand the substrate110fare not melted during the welding process. In addition,FIG.6shows that the welding part170fconnects the side surface S of the counterweight member120fand the first surface111fof the substrate110f; however, it is understood that the welding part170fcan also be sandwiched between the counterweight member120fand the first surface111fof the substrate110f(opposite to the second surface112fof the substrate110f). In this embodiment, for example, the welding part170fis solder and melted by arc welding, so that the melted welding part170fis connected between the substrate110fand the counterweight member120f. The counterweight member120fcan be fixed on the substrate110fafter the welding part170fis solidified.

FIG.7is a partial schematic cross-sectional view of a wavelength conversion element according to another embodiment of the invention. Different from the foregoing embodiments, the counterweight member120gis melted and connected to the first surface111gof the substrate110g(opposite to the second surface112gof the substrate110g) in the wavelength conversion element100gof this embodiment. For example, the material of the counterweight member120gmay include solder, and the solder is disposed on the first surface111gof the substrate110gby a high-temperature melting method. The counterweight member120gis formed after the molten solder is cooled and solidified. The above-mentioned high-temperature melting method is, for example, arc welding, but the invention is not limited thereto.

FIG.8is a block diagram of a projection device according to an embodiment of the invention. Please refer toFIG.8. The projection device200includes an illumination system210, a light valve220and a projection lens230. The illumination system210is adapted to provide an illumination beam L1. The light valve220is disposed on the transmission path of the illumination beam L1to convert the illumination beam L1into an image beam L2. The projection lens230is disposed on the transmission path of the image beam L2. The illumination system210includes an excitation light source211and a wavelength conversion element100a. The excitation light source211is adapted to provide an excitation beam Le. The wavelength conversion element100ais disposed on the transmission path of the excitation beam Le. Since the characteristics of the wavelength conversion element100ahave been described in detail in the foregoing, no redundant detail is to be given herein.

In some embodiments, the illumination system210includes an excitation light source211and a wavelength conversion element100a. The excitation light source211includes, for example, a light emitting diode (LED) or a laser diode (LD), wherein the number of the light emitting diodes or laser diodes may be one or more. For example, the light emitting diodes (or laser diodes) can be arranged in a matrix when the number of light emitting diodes (or laser diodes) is plural, but the invention is not limited thereto. The wavelength conversion element100ais disposed on the transmission path of the excitation beam Le to convert a part of the excitation beam Le into a converted beam Lp. In addition, the other part of the excitation beam Le is not converted into a converted beam by the wavelength conversion element100a(indicated by the beam Lr inFIG.8), and the beam Lr and the converted beam Lp form the illumination beam L1. In addition, the wavelength conversion layer130of the wavelength conversion element100areceives the excitation beam Le from the excitation light source211.

In some embodiments, the light valve220is, for example, a digital micromirror device (DMD), a liquid crystal on silicon (LCoS) or a liquid crystal display (LCD), but the invention not limited thereto. In addition, the invention does not limit the number of light valves. For example, the projection device200of this embodiment may adopt a structure of single-panel liquid crystal display panel or three-panel liquid crystal display panel, but the invention is not limited thereto.

In some embodiments, the projection lens230includes, for example, one or more optical lenses, and the diopter of the optical lenses may be the same or different from each other. For example, the optical lens may include various non-planar lenses such as biconcave lenses, biconvex lenses, meniscus lenses, convex-concave lenses, plano-convex lenses, and plano-concave lenses, or any combination of the foregoing non-planar lenses. On the other hand, the projection lens230may also include a flat optical lens. The invention does not limit the type and configuration of the projection lens230.

In some embodiments, the projection device200has good reliability due to adopting the wavelength conversion element100a. In addition, the wavelength conversion element100ain the projection device200can also be replaced with the wavelength conversion elements100b,100c,100d,100e,100f, or100gof the other embodiments described above.

In summary, because the invention adopts the wavelength conversion element in which the counterweight member is welded to the substrate, it is not necessary to use the adhesive material with poor temperature resistance to fix the counterweight member, so that the wavelength conversion element of the invention has better reliability. On the other hand, the projection device of the invention can also have better reliability due to adopting the above-mentioned wavelength conversion element.