Patent Publication Number: US-2023161236-A1

Title: Wavelength conversion element and projector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application serial no. 202111400024.2, filed on Nov. 24, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to an optical element and a projector, and more particularly relates to a wavelength conversion element and a projector having the wavelength conversion element. 
     Description of Related Art 
     The function provided by a wavelength conversion element in a projection device is to convert a wavelength of light. With a wavelength conversion material coated on the surface of the wavelength conversion element, after an excitation beam irradiates the wavelength conversion material, the wavelength conversion material can be excited to emit light of different colors. However, the excitation beam generates a large amount of heat energy during the excitation process. If the heat energy cannot be effectively dissipated, the efficiency of wavelength conversion will decrease and the projection quality of the projection device will be affected. 
     The existing heat dissipation method is to generate an airflow field flowing through the surface of the wavelength conversion element through the rotation of the wavelength conversion element, and the heat dissipation is accelerated by the airflow field. However, the existing heat dissipation method still does not have ideal heat dissipation efficiency. Therefore, how to improve the heat dissipation efficiency of the wavelength conversion element is a research focus in the field. 
     The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology 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. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the disclosure was acknowledged by a person of ordinary skill in the art. 
     SUMMARY 
     The disclosure provides a wavelength conversion element with good heat dissipation performance. 
     The disclosure provides a projector, whose wavelength conversion element has good heat dissipation performance. 
     Other objectives and advantages of the disclosure can be further understood from the technical features disclosed in the disclosure. 
     To achieve one or part or all of the above-mentioned objectives or other objectives, an embodiment of the disclosure provides a wavelength conversion element, including a turntable, a wavelength conversion layer, and a porous structure. The turntable has a wavelength conversion region and a non-wavelength conversion region, and includes a central axis. The wavelength conversion layer is disposed in the wavelength conversion region of the turntable. The porous structure is disposed in the non-wavelength conversion region of the turntable, and a material of the porous structure includes foamed metal. 
     To achieve one or part or all of the above-mentioned objectives or other objectives, an embodiment of the disclosure provides a projector, including a light source, a light valve, a projection lens, and a wavelength conversion element. The light source is adapted to provide an illumination beam. The light valve is adapted to receive the illumination beam from the light source and convert the illumination beam into an image beam. The projection lens is adapted to receive the image beam from the light valve and project the image beam out of the projector. The wavelength conversion element is configured in a transmission path of the illumination beam and includes a turntable, a wavelength conversion layer, and a porous structure. The turntable has a wavelength conversion region and a non-wavelength conversion region, and includes a central axis. The wavelength conversion layer is disposed in the wavelength conversion region of the turntable. The porous structure is disposed in the non-wavelength conversion region of the turntable, and a material of the porous structure includes foamed metal. 
     In an embodiment of the disclosure, the porosity of the above-mentioned porous structure is 85-99%. 
     In an embodiment of the disclosure, the material of the above-mentioned porous structure includes aluminum, nickel, copper or graphite. 
     In an embodiment of the disclosure, the thermal conductivity of the above-mentioned porous structure is greater than the thermal conductivity of the turntable, and the thermal conductivity of the porous structure is 80-400 W/mK. 
     In an embodiment of the disclosure, the above-mentioned turntable has a first surface and a second surface opposite to each other, a part of the first surface is the wavelength conversion region, and other parts of the first surface and the second surface are the non-wavelength conversion region. The porous structure is disposed on the second surface, and the orthographic projections of the porous structure and the wavelength conversion layer on the turntable along a direction parallel to the central axis completely overlap or partially overlap. 
     In an embodiment of the disclosure, the orthographic projection of the above-mentioned porous structure on the turntable along the direction parallel to the central axis is greater than the orthographic projection of the wavelength conversion layer on the turntable along the direction parallel to the central axis. 
     In an embodiment of the disclosure, the above-mentioned turntable has a first surface and a second surface opposite to each other, a part of the first surface is the wavelength conversion region, and other parts of the first surface and the second surface are the non-wavelength conversion region. The porous structure is disposed on the other parts of the first surface, and the orthographic projections of the porous structure and the wavelength conversion layer on the turntable along a direction parallel to the central axis do not overlap. 
     In an embodiment of the disclosure, the orthographic projection of the above-mentioned porous structure on the turntable along the direction parallel to the central axis has an annular shape or a circular shape. 
     In an embodiment of the disclosure, the above-mentioned turntable and the porous structure are integrally formed. 
     In an embodiment of the disclosure, the above-mentioned porous structure has at least one slot to form an airflow channel on the turntable. 
     Based on the aforementioned, embodiments of the disclosure at least have one of the following advantages or effects. In the disclosure, a porous structure made of foamed metal is arranged in the non-wavelength conversion region of the turntable of the wavelength conversion element. Thus, when the wavelength conversion element rotates, the airflow generated on the surface of the wavelength conversion element flows through the porous structure and then forms a disturbed airflow field, which helps to improve the heat dissipation efficiency. In addition, due to porous characteristics, the porous structure increases the heat dissipation area, and can also improve the heat dissipation efficiency of the wavelength conversion element. 
     Other objectives, features and advantages of the present disclosure will be further understood from the further technological features disclosed by the embodiments of the present disclosure wherein there are shown and described preferred embodiments of this disclosure, simply by way of illustration of modes best suited to carry out the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG.  1    is a schematic diagram of a projector according to an embodiment of the disclosure. 
         FIG.  2 A  is a schematic diagram of the wavelength conversion element shown in  FIG.  1   . 
         FIG.  2 B  is a front view of the wavelength conversion element shown in  FIG.  2 A . 
         FIG.  2 C  is a rear view of the wavelength conversion element shown in  FIG.  2 A . 
         FIG.  2 D  is a side view of the wavelength conversion element shown in  FIG.  2 A . 
         FIG.  3 A  is a side view of a wavelength conversion element according to another embodiment of the disclosure. 
         FIG.  3 B  is a rear view of the wavelength conversion element shown in  FIG.  3 A . 
         FIG.  4    is a side view of a wavelength conversion element according to another embodiment of the disclosure. 
         FIG.  5    is a side view of a wavelength conversion element according to another embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present disclosure can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
       FIG.  1    is a schematic diagram of a projector according to an embodiment of the disclosure. Please refer to  FIG.  1   , a projector  100  of the embodiment includes a light source  110 , a wavelength conversion element  120 , a light valve  130  and a projection lens  140 . The light source  110  provides an excitation beam Le, and the wavelength conversion element  120  is arranged in a transmission path of the excitation beam Le for converting the excitation beam Le into a conversion beam Lc of different wavelengths. An illumination beam L 1  includes at least one of the excitation beam Le and the conversion beam Lc. The light valve  130  is disposed in a transmission path of the illumination beam L 1  for converting the illumination beam L 1  into an image beam L 2 . The projection lens  140  is disposed in a transmission path of the image beam L 2  for receiving the image beam L 2  from the light valve  130  and projecting the image beam L 2  out of the projector  100 . 
       FIG.  2 A  is a schematic diagram of the wavelength conversion element of  FIG.  1   , and  FIG.  2 B ,  FIG.  2 C , and  FIG.  2 D  are a front view, a rear view, and a side view of  FIG.  2 A , respectively. Please refer to  FIG.  2 A  to  FIG.  2 D , a wavelength conversion element  120 A ( 120 ) of the embodiment includes a turntable  121 , a wavelength conversion layer  122 , and a porous structure  123 A. The turntable  121  has a wavelength conversion region R 1  (marked in  FIG.  2 D ) and a non-wavelength conversion region R 2  (marked in  FIG.  2 D ), and includes a central axis A. The wavelength conversion layer  122  is disposed in the wavelength conversion region R 1  of the turntable  121  for receiving the excitation beam Le provided by the light source  110 . The porous structure  123 A is, for example, a foamed metal material, including graphite, aluminum, aluminum alloy, nickel, nickel alloy, and/or copper, and is disposed in the non-wavelength conversion region R 2  of the turntable  121 . 
     In this configuration, when the wavelength conversion element  120 A rotates with the central axis A as the rotation axis, an airflow F generated on the surface of the wavelength conversion element  120  flows through the porous structure  123 A to form a disturbed airflow field, which helps to improve heat dissipation efficiency. In addition, due to porous characteristics, the porous structure  123 A increases the heat dissipation area of the turntable  121 , and can also improve the heat dissipation efficiency of the wavelength conversion element  120 . 
     In the embodiment, the porosity of the porous structure  123 A is 85% to 99%, so as to increase the porosity and effectively form a disturbed flow field and increase the heat dissipation area as described above. In addition, the thermal conductivity of the porous structure  123 A of the embodiment is 80-400 W/mK, that is, the thermal conductivity of the porous structure  123 A is greater than the thermal conductivity of the turntable  121 , so as to improve the heat dissipation efficiency of the wavelength conversion element  121 . 
     In detail, the turntable  121  of the wavelength conversion element  120 A of the embodiment has a first surface  1211  and a second surface  1212  opposite to each other, and the first surface  1211  of the turntable  121  is, for example, a light-receiving surface. Part of the first surface  1211  of the turntable  121  is a wavelength conversion region R 1 , and other parts of the first surface  1211  and the second surface  1212  of the turntable  121  are a non-wavelength conversion region R 2 . The porous structure  123 A is disposed on the second surface  1212  of the turntable  121 , and the orthographic projection of the porous structure  123 A on the turntable  121  along a direction parallel to the central axis A is, for example, an annular shape. The orthographic projections of the porous structure  123 A and the wavelength conversion layer  122  on the turntable  121  along the direction parallel to the central axis A at least partially overlap, so as to effectively dissipate the heat of the wavelength conversion layer  122 . Specifically, the orthographic projection of the porous structure  123 A on the turntable  121  along the direction parallel to the central axis A is, for example, greater than the orthographic projection of the wavelength conversion layer  122  on the turntable  121  along the direction parallel to the central axis A. In other embodiments, the orthographic projections of the porous structure  123 A and the wavelength conversion layer  122  on the turntable  121  along the direction parallel to the central axis A may completely overlap, which is not limited in the disclosure. 
     In the embodiment, the porous structure  123 A is disposed in the non-wavelength conversion region R 2  on the turntable  121  by, for example, welding. However, the disclosure is not limited thereto. In other embodiments, the turntable  121  and the porous structure  123 A may be integrally formed, and the materials of the turntable  121  and the porous structure  123 A may both are foamed metal. Alternatively, the non-wavelength conversion region R 2  of the turntable  121  and the porous structure  123 A are integrally formed, and both are foamed metal. The wavelength conversion region R 1  of the turntable  121  is made of a metal material with low porosity. 
       FIG.  3 A  is a side view of a wavelength conversion element according to another embodiment of the disclosure, and  FIG.  3 B  is a rear view of the wavelength conversion element of  FIG.  3 A . Please refer to  FIG.  3 A  to  FIG.  3 B . The wavelength conversion element  120 B ( 120 ) of the embodiment is similar to the wavelength conversion element  120 A of  FIG.  2 D . The difference between the two is that the orthographic projection of the porous structure  123 A of the wavelength conversion element  120 B on the turntable  121  along the direction parallel to the central axis A is a circular shape, which has a larger coverage area, that is, the porous structure  123 B covers the central area on one side of the turntable  121 , and the orthographic projection of the porous structure  123 B on the turntable  121  along the direction parallel to the central axis A at least overlaps the orthographic projection of the wavelength conversion layer  122  on the turntable  121  along the direction parallel to the central axis A. Therefore, when flowing through the porous structure  123 B, an airflow passes through more pores, which helps to disturb the airflow field and helps with the heat dissipation of the wavelength conversion element  120 B. 
       FIG.  4    is a side view of a wavelength conversion element according to another embodiment of the disclosure. Please refer to  FIG.  4   . The wavelength conversion element  120 C ( 120 ) of the embodiment is similar to the wavelength conversion element  120 A of  FIG.  2 D . The difference between the two is that the porous structure  123 C of the wavelength conversion element  120 C is disposed on the non-wavelength conversion region R 2  of the first surface  1211  of the turntable  121 . Therefore, the orthographic projections of the porous structure  123 C and the wavelength conversion layer  122  on the turntable  121  along the direction parallel to the central axis A do not overlap, so as to avoid affecting the excitation of the excitation beam Le. In other embodiments, the porous structure  123 C of the wavelength conversion element  120 C ( 120 ) can, for example, replace a hub originally arranged on the rotation axis, that is, foamed metal (porous structure  123 C) can be used as the hub. 
       FIG.  5    is a side view of a wavelength conversion element according to another embodiment of the disclosure. Please refer to  FIG.  5   . The wavelength conversion element  120 D ( 120 ) of the embodiment is similar to the wavelength conversion element  120 C of  FIG.  4   . The difference between the two is that the porous structure  123 D of the wavelength conversion element  120 D also has at least one slot  1231 , which forms an airflow channel on the turntable  121 . When an airflow flows through the porous structure  123 D, part of the airflow directly passes through the at least one slot  1231  (airflow channel) and part of the airflow passes through or disturbs the pores of the porous structure  123 D, which expedites the heat dissipation of the wavelength conversion element  120 D. 
     In summary, embodiments of the disclosure at least have one of the following advantages or effects. In the disclosure, the porous structure made of foamed metal is arranged in the non-wavelength conversion region of the turntable of the wavelength conversion element. Thus, when the wavelength conversion element rotates, the airflow generated on the surface of the wavelength conversion element flows through the porous structure and then forms the disturbed airflow field, which helps to improve the heat dissipation efficiency. In addition, due to porous characteristics, the porous structure increases the heat dissipation area, and can also improve the heat dissipation efficiency of the wavelength conversion element. 
     The foregoing description of the preferred embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the disclosure and its best mode practical application, thereby to enable persons skilled in the art to understand the disclosure for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the disclosure be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the disclosure”, “the present disclosure” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the disclosure does not imply a limitation on the disclosure, and no such limitation is to be inferred. The disclosure is limited only by the spirit and scope of the appended claims. Moreover, these claims may refer to use “first”, “second”, etc. following with noun or element. Such terms should be understood as a nomenclature and should not be construed as giving the limitation on the number of the elements modified by such nomenclature unless specific number has been given. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the disclosure. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present disclosure as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.