Patent Publication Number: US-2023140583-A1

Title: Light source module

Description:
This application claims the benefit of Taiwan application Serial No. 110140444, filed Oct. 29, 2021, the subject matter of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The disclosure relates in general to a light source module. 
     BACKGROUND 
     The application of a light source modules is wide, and many devices such as a projector, an illuminator, a flashlight, etc. needs the light source modules. Generally speaking, the greater the luminous brightness of the light source module is, the wider the application of the light source module is and the better the lighting effect is. Therefore, submitting a new light source module capable of providing higher brightness is one of the goals of the industry in this technical field. 
     SUMMARY 
     According to an embodiment, a light source module is provided. The light source module includes a first light-splitting element, a second light-splitting element, a first light source, a second light source and a third light source. The first light source is configured to emit a first light having a first wavelength to the first light-splitting element in a first optical path direction. The second light source is configured to emit a second light having the first wavelength to the second light-splitting element in a second optical path direction opposite to the second optical path direction. The third light source is configured to emit a third light having a second wavelength to travel in a third optical path direction, wherein the third optical path direction is substantially perpendicular to the first optical path direction, and the second wavelength is different from the first wavelength. The first light source includes a first reflective layer, the second light source includes a second reflective layer, and the first reflective layer and the second reflective layer are configured to reflect light having the first wavelength. 
     The above and other aspects of the disclosure will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment (s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A and  1 B  show schematic diagrams of a light source module according to an embodiment of the present invention; 
         FIG.  2    shows a schematic diagram of the optical path of a light source module according to another embodiment of the present invention; 
         FIG.  3    shows a schematic diagram of the optical path of a light source module according to another embodiment of the present invention; 
         FIG.  4    shows a schematic diagram of the optical path of a light source module according to another embodiment of the present invention; 
         FIG.  5    shows a schematic diagram of the optical path of a light source module according to another embodiment of the present invention; and 
         FIG.  6    shows a schematic diagram of the optical path of a light source module according to another embodiment of the present invention. 
     
    
    
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     DETAILED DESCRIPTION 
     Referring to  FIGS.  1 A and  1 B ,  FIGS.  1 A and  1 B  show schematic diagrams of a light source module  100  according to an embodiment of the present invention. The light source module  100  could be applied to a device such as a projector, an illuminator, a display or other types of devices that needs a light source. For the projector, the light source module  100  is also referred to as a light combining module. 
     The light source module  100  includes a first light source  110 A, a second light source  110 B, a third light source  110 C, a fourth light source  110 D, a first light-splitting element  120 A, a second light-splitting element  120 B, a third light-splitting element  120 C, and at least one condensing lens, for example, a first condensing lens  130 A, a second condensing lens  130 B and a third condensing lens  130 C. 
     As shown in  FIG.  1 A , the first light source  110 A is configured to emit a first light L 1  (including light L 11  and light L 12 ) having a first wavelength to the first light-splitting element  120 A in a first optical path direction P 1 . As shown in  FIG.  1 B , the second light source  110 B is configured to emit a second light L 2  (including light L 21  and light L 22 ) having the first wavelength to the second light-splitting element  120 B in the second optical path direction P 2  opposite to the first optical path direction P 1 . The third light source  110 C is configured to emit a third light L 3  having a second wavelength to travel in a third optical path direction P 3  substantially perpendicular to the first optical path direction P 1 . 
     The second wavelength is different from the first wavelength. The first light source  110 A includes a first reflective layer  110 A 1 , and the second light source  110 B includes a second reflective layer  110 B 1 . The first reflective layer  110 A 1  and the second reflective layer  110 B 1  are configured to reflect light, for example, the first reflective layer  110 A 1  reflects a portion of the second light L 2  (e.g., the fourth part L 22  which will be described later), and the second reflective layer  110 B 1  reflects a portion of the first light L 1  (e.g., the second part L 12  which will be described later. As a result, an optical path length of the first light L 1  could be shortened due to the arrangement of the first light-splitting element  120 A, and an optical path length of the second light L 2  could be shortened due to the arrangement of the second light-splitting element  120 B. In addition, due to the first light source  110 A and the second light source  110 B having the same wavelength and oppositely disposed, it could increase the brightness of the light source module  100 . 
     In the present embodiment, the first wavelength ranges, for example, between 495 nanometers (nm) and 570 nm, and the second wavelength ranges, for example, between 450 nm and 475 nm, or between 620 nm and 750 nm. Furthermore, the first light L 1  and the second light L 2  are, for example, green light, and the third light L 3  is, for example, blue light or red light. Green light accounts for about 70% of white light. The higher the proportion of green light is, the higher the brightness of white light is. Since the light emitted by the light source module  100  includes mixed light of two beams of the green light (the first light L 1  and the second light L 2 ), the brightness of the white light emitted by the light source module  100  could be enhanced. 
     As shown in  FIGS.  1 A and  1 B , the first light source  110 A and the second light source  110 B are disposed opposite to each other. The first light source  110 A and the second light source  110 B are disposed in a first center line S 1 . For example, the first center line S 1  passes through a center of the first light source  110 A and a center of the second light source  110 B. The first light source  110 A and the second light source  110 B are divided into two halves by the first center line S 1 . As a result, the first light L 1  emitted by the first light source  110 A is divided into a first part L 11  and a second part L 12  relative to the first center line S 1 . The first part L 11  is incident to the first light-splitting element  120 A in the first optical path direction P 1  above the first center line S 1 , and is reflected to a module  10  through the first light-splitting element  120 A and the third light-splitting element  120 C in order, wherein the module  10  is, for example, an illuminating module or an imaging module. The second part L 12  is incident to the second light source  110 B in the first optical path direction P 1 , and is reflected by the second reflective layer  110 B 1  of the second light source  110 B (the reflected light is hereinafter referred to as the second reflected part L 12 ′). The optical path of the second reflected part L 12 ′ is similar to or the same as the optical path of the second light L 2  of the second light source  110 B (as shown in  FIG.  1 B ). The optical path of the second light L 2  will be described later. 
     As shown in  FIG.  1 B , the second light L 2  emitted by the second light source  110 B is divided into a third part L 21  and a fourth part L 22  relative to the first center line S 1 . The third part L 21  is incident to the second light-splitting element  120 B in the second optical path direction P 2  above the first center line S 1 , and is reflected to the module  10  through the second light-splitting element  120 B and the third light-splitting element  120 C in order. The fourth part L 22  is incident to the first light source  110 A in the second optical path direction P 2 , and is reflected by the first reflective layer  110 A 1  of the first light source  110 A (the reflected light is hereinafter referred to as the fourth reflected part L 22 ′). The optical path of the fourth reflected part L 22 ′ is similar to or the same as the optical path (as shown in  FIG.  1 A ) of the first light L 1  of the first light source  110 A, and the similarities will not be repeated here. 
     Similar to the optical path of the second light L 2 , a portion of the second reflected part L 12 ′ ( FIG.  1 A ) is incident to the first light source  110 A, and another portion travels to the module  10 . Similar to the optical path of the first light L 1 , a portion of the fourth reflected part L 22 ′ ( FIG.  1 B ) is incident to the second light source  110 B, and another part travels to the module  10 . According to such structure, the light utilization rate could be increased. After the first light L 1  and the second light L 2  are reflected several times, light is finally emitted from the light source module  100 . 
     Although the optical path of the first light L 1  and the optical path of the second light L 2  are shown in  FIGS.  1 A and  1 B  respectively, the optical path of the first light L 1  shown in  FIG.  1 A  and the optical path of the second light L 1  shown in  FIG.  1 B  could be occur simultaneously. 
     As shown in  FIG.  1 A , the first light source  110 A further includes a first light-emitting layer  110 A 2  and a first wavelength conversion layer  110 A 3 . The first light-emitting layer  110 A 2  is formed between the first wavelength conversion layer  110 A 3  and the first reflective layer  110 A 1 , and the first wavelength conversion layer  110 A 3  is closer to the second light source  110 B than the first reflective layer  110 A 1 . The first light-emitting layer  110 A 2  includes, for example, at least one semiconductor epitaxial layer which could emit light L 1   a , and the first wavelength conversion layer  110 A 3  could convert the light L 1   a  into the first light L 1  having the first wavelength. In the present embodiment, the light L 1   a  is, for example, light having the second wavelength, such as blue light or red light. The first wavelength conversion layer  110 A 3  includes a plurality of fluorescent particles  110 A 4  which could excite light for converting the wavelength of the light. For example, the first wavelength conversion layer  110 A 3  converts the light L 1   a  (e.g., blue light) into the first light L 1  (e.g., green light) of the first wavelength. In another embodiment, the light L 1   a  emitted by the first light-emitting layer  110 A 2  could be the first light L 1  having the first wavelength, and, in this example, the first light source  110 A could omit the first wavelength conversion layer  110 A 3 . 
     As shown in  FIG.  1 B , the second light source  110 B further includes a second light-emitting layer  110 B 2  and a second wavelength conversion layer  110 B 3 . The second light emitting layer  110 B 2  is formed between the second wavelength conversion layer  110 B 3  and the second reflective layer  110 B 1 , and the second wavelength conversion layer  110 B 3  is closer to the first light source  110 A than the second reflective layer  110 B 1 . The second light-emitting layer  110 B 2  includes, for example, at least one semiconductor epitaxial layer which could emit light L 2   a . The second wavelength conversion layer  110 B 3  could convert the light L 2   a  into the second light L 2  having the first wavelength. In the present embodiment, the light L 2   a  is, for example, light having the second wavelength, such as blue light or red light. The second wavelength conversion layer  110 B 3  includes a plurality of fluorescent particles  110 B 4  which could excite light for converting the light wavelength. For example, the second wavelength conversion layer  110 B 3  converts the light L 2   a  (e.g., blue light) into the second light L 2  (e.g., green light) having the first wavelength. In another embodiment, the light L 2   a  emitted by the second light-emitting layer  110 B 2  could be the second light L 2  having the first wavelength, and, in this example, the second light source  110 B could omit the second wavelength conversion layer  110 B 3 . 
     As shown in  FIG.  1 A , the third light source  110 C is disposed on a side of the first center line S 1 . In addition, the third light source  110 C is disposed in the second center line S 2 , so that the third light L 3  emitted by the third light source  110 C is divided into two parts L 31  and L 32  relative to the second center line S 2 . In addition, the second center line S 2  passes through a center of the third light source  110 C. As a result, the two parts L 31  and L 32  of the third light L 3  have substantially the same amount of light relative to the second center line S 2 . 
     As shown in  FIG.  1 A , the fourth light source  110 D is configured to emit fourth light L 4  having a third wavelength to the third light-splitting element  120 C in the first optical path direction P 1 . The third wavelength is different from the first wavelength and the second wavelength. In an embodiment, the second wavelength ranges, for example, between 450 nm and 475 nm, and the third wavelength ranges, for example, between 620 nm and 750 nm. Furthermore, the third light L 3  is, for example, blue light, and the fourth light L 4  is, for example, red light. 
     As shown in  FIG.  1 A , the fourth light source  110 D is disposed in a center line S 3 . As a result, the fourth light L 4  emitted by the fourth light source  110 D is divided into a fifth part L 41  and a sixth part L 42  relative to the center line S 3 . In addition, the center line S 3  passes through a center of the fourth light source  110 D, so that the fifth part L 41  and the sixth part L 42  of the fourth light L 4  have substantially the same amount of light relative to the center line S 3 . 
     As shown in  FIG.  1 A , the first light-splitting element  120 A is disposed opposite to the first light source  110 A. The first light-splitting element  120 A is located at a side of the first center line S 1 , such as the side close to the third light source  110 C, so that the first part L 11  of the first light L 1  is incident to the first light-splitting element  120 A, but the second part L 12  is not incident to the light-splitting element  120 A. As a result, the second part L 12  of the first light L 1  could be incident to the second light source  110 B to be reflected by the second light source  110 B. 
     As shown in  FIG.  1 B , the second light-splitting element  120 B is located at a side of the first centerline S 1 , such as the side close to the third light source  110 C, so that the third part L 21  of the second light L 2  is incident to the second light-splitting element  120 B, but the fourth part L 22  is not incident to the second light-splitting element  120 B. As a result, the fourth part L 22  of the second light L 2  could be incident to the first light source  110 A to be reflected by the first light source  110 A. 
     As shown in  FIG.  1 A , there is an interval SP between the first light-splitting element  120 A and the second light-splitting element  1208 , that is, the first light-splitting element  120 A and the second light-splitting element  120 B are separately disposed. The second center line S 2  passes through the interval SP, for example. As a result, at least one portion of the third light L 3  travels through the interval SP in the third optical path direction P 3 , that is, at least such portion does not travel through the physical materials of the first light-splitting element  120 A and the second light-splitting element  120 B. In addition, the first light-splitting element  120 A and the second light-splitting element  120 B are disposed opposite to the third light source  110 C. For example, the first light-splitting element  120 A and the second light-splitting element  120 B are respectively disposed on opposite two sides of the second center line S 2 . As a result, the fifth part L 31  and the sixth part L 32  of the third light L 3  could pass through the second light-splitting element  120 B and the first light-splitting element  120 A respectively. In another embodiment, the first light-splitting element  120 A and the second light-splitting element  120 B could be connected to each other, for example, the first light-splitting element  120 A and the second light-splitting element  120 B are integrated into one piece. As a result, the entire third light L 3  travels through, in the third optical path direction P 3 , the physical materials of the first light-splitting element  120 A and the second light-splitting element  120 B. 
     As shown in  FIG.  1 A , the first light-splitting element  120 A and the second light-splitting element  120 B are disposed opposite to the third light source  110 C. For example, the first light-splitting element  120 A and the second light-splitting element  120 B are disposed on opposite two sides of the second centerline S 2  respectively, so that the two parts L 31  and L 32  of the third light L 3  could be incident to the first light-splitting element  120 A and the light-splitting element  120 B respectively. 
     As shown in  FIG.  1 A , the third light-splitting element  120 C is disposed opposite to the third light source  110 C. The second center line S 2  passes through the third light source  110 C and the third light-splitting element  120 C, for example, passes through the center of the third light source  110 C and the third light-splitting element  120 C. As a result, the entire third light L 3  emitted by the third light source  110 C could be incident to the third light-splitting element  120 C. In addition, the third light-splitting element  120 C is disposed opposite to the fourth light source  110 D. The center line S 3  passes through the fourth light source  110 D and the third light-splitting element  120 C, for example, travels through the center of the fourth light source  110 D and the center of the third light-splitting element  120 C. As a result, the entire fourth light L 4  emitted by the fourth light source  110 D could be incident to the third light-splitting element  120 C. 
     In terms of the arrangement position of the light-splitting element, as shown in  FIG.  1 A , an angle A 1  of the third light-splitting element  120 C with respect to a horizontal reference line is 45 degrees, for example, so that the light reflected by the third light-splitting element  120 C travels in the first optical path direction P 1 . In another embodiment, the angle A 1  of the third light-splitting element  120 C with respect to the horizontal reference line could be 135 degrees or −45 degrees, and the fourth light source  110 D could be disposed on another side of the third light-splitting element  120 C of  FIG.  1 A . As a result, the light reflected by the third light-splitting element  120 C could travel in the second optical path direction P 2 . In addition, the angle A 1  of the first light-splitting element  120 A with respect to the horizontal reference line is, for example, 45 degrees, and the angle A 1  of the second light-splitting element  120 B with respect to the horizontal reference line is, for example, 135 degrees or −45 degrees. 
     In terms of light-splitting characteristics, the light-splitting element is, for example, a dichroic mirror. As shown in  FIGS.  1 A and  1 B , the first light-splitting element  120 A could reflect the first light L 1  having the first wavelength (for example, the green light spectrum) but allows the third light L 3  having the second wavelength (for example, blue light spectrum) to travel through. The second light-splitting element  120 B could reflect the second light L 2  having the first wavelength (for example, the green light spectrum) but allows the third light L 3  of the second wavelength (for example, the blue light spectrum) to travel through. The third light-splitting element  120 C could reflect the first light L 1  and the second light L 2  having the first wavelength (for example, the green light spectrum) and reflect the third light L 3  having the second wavelength (for example, the blue light spectrum), but allow the fourth light L 4  having three wavelengths (for example, the red light spectrum) to travel through. 
     The condensing lens could condense the light emitted by the light source, so that the light traveling through the condensing lens becomes collimated light. The condensing lens includes at least one lens, for example, a spherical lens, an aspheric lens or a combination thereof. 
     As shown in  FIG.  1 A , the first condensing lens  130 A is disposed opposite to the first light source  110 A. The first condensing lens  130 A is disposed in the first center line S 1 . For example, the first center line S 1  passes through a center of the first condensing lens  130 A, so that the first part L 11  and the second part L 12  incident to the first condensing lens  130 A have substantially the same amount of light relative to the first center line S 1 . 
     As shown in  FIG.  1 A , the second condensing lens  1308  is disposed opposite to the second phase light source  110 B. The second condensing lens  1308  is disposed in the first center line S 1 . For example, the first center line S 1  passes through the center of the second condensing lens  1308  so that the third part L 21  and the fourth part L 22  incident to the second condensing lens  1308  have substantially the same amount of light relative to the first center line S 1 . 
     As shown in  FIG.  1 A , the third condensing lens  130 C is disposed opposite to the third light source  110 C. The third condensing lens  130 C is disposed in the second center line S 2 . For example, the second center line S 2  passes through a center of the third condensing lens  130 C, so that the fifth part L 31  and the sixth part L 32  incident to the third condensing lens  130 C have substantially the same amount of light relative to the second center line S 2 . 
     As shown in  FIG.  1 A , the fourth condensing lens  130 D is disposed opposite to the fourth light source  110 D. The fourth condensing lens  130 D is disposed in the center line S 3 . For example, the center line S 3  passes through a center of the fourth condensing lens  130 D, so that the fifth part L 41  and the sixth part L 42  incident to the fourth condensing lens  130 D have substantially the same amount of light relative to the center line S 3 . 
     Referring to  FIG.  2   ,  FIG.  2    shows a schematic diagram of the optical path of a light source module  200  according to another embodiment of the present invention. The light source module  200  includes the first light source  110 A, the second light source  1106 , the third light source  110 C, the fourth light source  110 D, the first light-splitting element  120 A, the second light-splitting element  120 B, the third light-splitting element  120 C and at least one condensing lens (for example, the first A condensing lens  130 A, the second condensing lens  130 B, the third condensing lens  130 C), a first reflective element  240 A and a second reflective element  240 B. The light source module  200  of the embodiment of the present invention has the features similar to or the same as that of the light source module  100  expect that the light source module  200  further includes at least one reflective element, such as at least one reflective mirror. 
     As shown in  FIG.  2   , the first reflective element  240 A is disposed opposite to the first light source  110 A. The first part L 11  of the first light L 1  is incident to the first light-splitting element  120 A in the first optical path direction P 1  and reflected to the module  10  through the first light-splitting element  120 A and the third light-splitting element  120 C. The second part L 12  of the first light L 1  is incident to the first reflective element  240 A in the first optical path direction P 1  and reflected back the first light source  110 A from the first reflective element  240 A (the reflected light is hereinafter referred to as the second reflected part L 12 ′). The second reflected part L 12 ′ reflected from the first light source  110 A becomes a second reflected part L 12 ″. The optical path of such second reflected part L 12 ″ is similar to or the same as the optical path of the first light L 1 , and the similarities will not be repeated here. 
     In addition, due to the arrangement of the first reflective element  240 A, the light (spot) reflected back the first light source  110 A from the first reflective element  240 A will not be misaligned with the first light source  110 A, and accordingly it could obtain a better matching effect of object-side image. In addition, since the light (spot) reflected back the first light source  110 A from the first reflective element  240 A will not be misaligned with the first light source  110 A, the light (spot) reflected back the first light source  110 A from the first reflective element  240 A could be completely reflected by the first reflective layer  110 A 1  of the first light source  110 A, and thus the problem of light leakage would not occur. 
     As shown in  FIG.  2   , the second reflective element  240 B is disposed opposite to the second light source  110 B. The third part L 21  of the second light L 2  is incident to the second light-splitting element  120 B in the second optical path direction P 2  and reflected to the module  10  through the second light-splitting element  120 B and the third light-splitting element  120 C. The fourth part L 22  of the second light L 2  is incident to the second reflective element  240 B in the second optical path direction P 2  and reflected back the second light source  110 B from the second reflective element  240 B (the reflected light is hereinafter referred to as the fourth reflected part L 22 ′). The fourth reflected part L 22 ′ reflected by the second light source  110 B becomes a fourth reflected part L 22 ″. The optical path of the fourth reflected part L 22 ″ is similar to or the same as the optical path of the second light L 2 , and the similarities will not be repeated here. 
     In addition, due to the arrangement of the second reflective element  240 B, the light (spot) reflected back the second light source  110 B from the second reflective element  240 B will not be misaligned with the second light source  110 B, and accordingly it could obtain a better matching effect of object-side image. In addition, since the light (spot) reflected back the second light source  110 B from the second reflective element  240 B will not be misaligned with the second light source  110 B, the light (spot) reflected back the second light source  110 B from the second reflective element  240 B could be completely reflected by the second reflective layer  110 B, and thus the problem of light leakage would not occur. 
     As shown in  FIG.  2   , the first light source  110 A and the second light source  110 B are disposed in the first center line S 1 . The first light-splitting element  120 A and the first reflective element  240 A are disposed on opposite two sides of the first center line S 1  respectively. As a result, the first part L 11  and the second part L 12  of the first light L 1  are incident to the first light-splitting element  120 A and the first reflective element  240 A respectively. Similarly, the second light-splitting element  1208  and the second reflective element  240 B are respectively disposed on opposite two sides of the first center line S 1 . As a result, the third part L 21  and the fourth part L 22  of the second light L 2  are incident to the second light-splitting element  1208  and the second reflective element  240 B, respectively. 
     As shown in  FIG.  2   , the first reflective element  240 A is located outside the optical path of the first part L 11  of the first light L 1  (that is, the first reflective element  240 A is not located at the optical path of the first part L 11 ), and thus it could prevent from being blocking the traveling of the first part L 11  or reduce the amount of the blocked first part L 11 . The second reflective element  240 B is located outside the optical path of the third part L 21  of the second light L 2  (that is, the second reflective element  240 B is not located at the optical path of the third part L 21 ), and thus it could prevent from being blocking the traveling of the third part L 21  of the second light L 2  or reduce the amount of the blocked first part L 11 . 
     Referring to  FIG.  3   ,  FIG.  3    shows a schematic diagram of the optical path of a light source module  300  according to another embodiment of the present invention. The light source module  300  includes the first light source  110 A, the second light source  110 B, the third light source  110 C, a fourth light source  310 D, a fifth light source  310 E, the first light-splitting element  120 A, the second light-splitting element  120 B, the third light-splitting element  120 C, at least one condensing lens (for example, the first condensing lens  130 A, the second condensing lens  130 B, the third condensing lens  130 C, the fourth condensing lens  130 D, a fifth condensing lens  330 E), the first reflective element  240 A, the second reflective element  240 B, a third reflective element  340 A, a fourth The reflective element  340 B and a fifth reflective element  340 C. 
     The third light source  110 C is configured to emit the third light L 3  having the second wavelength, the fourth light source  310 D is configured to emit the fourth light L 4  having the third wavelength, and the fifth light source  310 E is configured to emit the fifth light L 5  having the third wavelength. In the present embodiment, the third light L 3  is, for example, blue light, and the fourth light L 4  and the fifth light L 5  are, for example, red light. 
     The fifth light source  310 E is disposed in a fourth center line S 4 , for example, the fourth center line S 4  passes through a center of the fifth light source  310 E. The fifth light L 5  is divided into a seventh part L 51  and an eighth part L 52  relative to the fourth center line S 4 . The fourth reflective element  340 B and the fifth reflective element  340 C are disposed on opposite two sides of the fourth center line S 4  respectively. As a result, the seventh part L 51  and the eighth part L 52  of the fifth light L 5  could be incident to the fourth reflective element  340 B and the fifth reflective element  340 C respectively. 
     Furthermore, the seventh part L 51  of the fifth light L 5  travels to the fourth reflective element  340 B in the fourth optical path direction P 4 , and is incident to the module  10  through the fourth reflective element  340 B and the third light-splitting element  120 C in order. The eighth part L 52  of the fifth light L 5  is reflected back the fifth light source  310 E from the fifth reflective element  340 C (the reflected light is hereinafter referred to as an eighth reflected part L 52 ′). The fifth light source  310 E includes a reflective layer  310 E 1 . The eighth reflected part L 52 ′ reflected by the reflective layer  310 E 1  becomes an eighth reflected part L 52 ″. The optical path of the eighth reflected part L 52 ″ is similar to or the same as the optical path of the fifth light L 5 , and the similarities will not be repeated here. In addition, the fourth optical path direction P 4  is opposite to the third optical path direction P 3 . 
     In an embodiment, the fifth light source  310 E further includes a light-emitting layer  310 E 2  and a wavelength conversion layer  310 E 3 . The light-emitting layer  310 E 2  is formed between the wavelength conversion layer  310 E 3  and the reflective layer  310 E 1 , and the wavelength conversion layer  310 E 3  is closer to the fifth condensing lens  330 E than the reflective layer  310 E 1 . The light-emitting layer  310 E 2  includes, for example, at least one semiconductor epitaxial layer which could emit light L 51   b . The wavelength conversion layer  310 E 3  converts the light L 51   b  into a fifth light L 5  having the second wavelength. The wavelength conversion layer  310 E 3  includes a plurality of fluorescent particle  310 E 4  which could excite an incident light for converting the incident light into a converted light having different wavelength. For example, the wavelength conversion layer  310 E 3  converts the light L 51   b  (e.g., blue light) into the fifth light L 5  (e.g., red light) having the second wavelength. In another embodiment, the light emitting layer  310 E 2  could directly emit red light, and, in such example, the fifth light source  310 E could omit the wavelength conversion layer  310 E 3 . 
     The third reflective element  340 A is disposed opposite to the fourth light source  310 D. For example, the third reflective element  340 A is disposed on a side of the center line S 3 , for example, the side close to the fifth light source  310 E. The fourth light L 4  includes the fifth part L 41  and the sixth part L 42 . The fifth part L 41  is incident to the third light-splitting element  120 C in the first optical path direction P 1  and incident to the module  10  travels through the third light-splitting element  120 C. The sixth part L 42  is incident to the third reflective element  340 A in the first optical path direction P 1  and reflected back to the fourth light source  310 D from the third reflective element  340 A (the reflected light is hereinafter referred to as a sixth reflected part L 42 ′). The fourth light source  310 D includes a reflective layer  310 D 1 . The sixth reflected part L 42 ′ reflected by the reflective layer  310 D 1  of the fourth light source  310 D becomes a sixth reflected part L 42 ″. The optical path of the sixth reflected part L 42 Δ is similar to or the same as the optical path of the fourth light L 4 , and the similarities will not be repeated here. 
     In an embodiment, the fourth light source  310 D further includes a light-emitting layer  310 D 2  and a wavelength conversion layer  310 D 3 . The light emitting layer  310 D 2  is formed between the wavelength conversion layer  310 D 3  and the reflective layer  310 D 1 , and the wavelength conversion layer  310 D 3  is closer to the fourth condensing lens  130 D than the reflective layer  310 D 1 . The light emitting layer  310 D 2  includes, for example, at least one semiconductor epitaxial layer which could emit light L 41   a . The wavelength conversion layer  310 D 3  converts the light L 41   a  into the fourth light L 4  having the second wavelength. The wavelength conversion layer  310 D 3  includes a plurality of fluorescent particles  310 D 4  which could excite an incident light for converting the incident light into a converted light having different wavelength. For example, the wavelength conversion layer  310 D 3  converts the light L 41   a  (e.g., blue light) into the fourth light L 4  (e.g., red light) having the second wavelength. In another embodiment, the light emitting layer  310 D 2  could directly emit red light, and, in such example, the fourth light source  310 D could omit the wavelength conversion layer  310 D 3 . 
     The fourth light source  110 D of the aforementioned embodiment has the features same as or similar to that of the fourth light source  310 D except that the fourth light source  110 D could selectively omit the reflective layer. 
     In addition, the fifth condensing lens  330 E is disposed opposite to the fifth light source  310 E. The fifth condensing lens  330 E is disposed on the fourth centerline S 4 . For example, the fourth centerline S 4  passes through a center of the fifth condensing lens  330 E, so that the seventh part L 51  and the eighth part L 52  incident to of the fifth condensing lens  330 E have substantially the same amount of light relative to the fourth center line S 4 . 
     Referring to  FIG.  4   ,  FIG.  4    shows a schematic diagram of the optical path of a light source module  400  according to another embodiment of the present invention. Although not shown, the optical path of the light source module  400  could further include the optical path of the first light L 1  emitted by the first light source  110 A and/or the optical path of the second light L 2  emitted by the second light source  110 B. 
     The light source module  400  includes the first light source  110 A, the second light source  110 B, the third light source  410 C, a fourth light source  410 D, a fifth light source  410 E, a first light-splitting element  420 A, a second light-splitting element  420 B, and a third light-splitting element  420 C and at least one condensing lens, for example, the first condensing lens  130 A, the second condensing lens  1308 , the third condensing lens  130 C, the fourth condensing lens  130 D and the fifth condensing lens  330 E. 
     The third light source  410 C is configured to emit the third light L 3  having the second wavelength to be incident to the first light-splitting element  420 A and the second light-splitting element  420 B in the third optical path direction P 3 . The fourth light source  410 D is configured to emit the fourth light L 4  having the third wavelength to be incident to the third light-splitting element  420 C in the first optical path direction P 1 . The fifth light source  410 E is configured to emit the fifth light L 5  having the third wavelength to be incident to the third light-splitting element  420 C in the fourth optical path direction P 4 . The first wavelength conversion layer  110 A 3  and the second wavelength conversion layer  110 B 3  are configured to convert the fifth light L 5  having the third wavelength into the light having the first wavelength. In the present embodiment, the third light L 3  is, for example, red light, and the fourth light L 4  and the fifth light L 5  are, for example, blue light. 
     The relative relationship among the third light source  410 C, the first light-splitting element  420 A and the second light-splitting element  420 B is similar to the relative relationship among the third light source  110 C, the first light-splitting element  420 A and the second light-splitting element  420 B, and the similarities will not be repeated here. The relative relationship between the fourth light source  410 D and the third light-splitting element  420 C is similar to the relative relationship between the fourth light source  110 D and the third light-splitting element  120 C, and the similarities will not be repeated here. 
     The fifth light source  410 E is disposed in the fourth center line S 4 , for example, the fourth center line S 4  passes through a center of the fifth light source  410 E. The fifth light L 5  is divided into the seventh part L 51  and the eighth part L 52  relative to the fourth center line S 4 . The seventh part L 51  travels to the first light source  110  through the fourth condensing lens  330 E, the third light-splitting element  420 C, the first light-splitting element  420 A and the first condensing lens  130 A. After the seventh part L 51  is converted into a converted light L 51   a  having the first wavelength by the first wavelength conversion layer  110 A 3  of the first light source  110 A, a portion of the converted light L 51   a  is reflected to the first condensing lens  130 A through the first reflective layer  110 A 1 , and another portion of the converted light L 51   a  could be directly reflected (not through the first reflective layer  110 A 1 ) to the first condensing lens  130 A by the fluorescent particles  110 A 4 . In addition, the seventh part L 51  that has not been converted by the fluorescent particles  110 A 4  could be reflected back the first wavelength conversion layer  110 A 3  by the first reflective layer  110 A 1  for increasing the probability of converting the light wavelength by the fluorescent particles  110 A 4 . The optical path of the converted light L 51   a  provided by the first light source  110 A is similar to or the same as the optical path of the first light L 1  (shown in  FIG.  1 A ) emitted by the first light source  110 A, and the similarities will not be repeated here. Similarly, after the eighth part L 52  is converted, by the second wavelength conversion layer  110 B 3  of the second light source  110 B, into the converted light L 52   a  having the first wavelength, a portion of the converted light L 52   a  is reflected to the second condensing lens  130 B through the second reflective layer  110 B 1 , and another portion of the converted light L 52   a  could be directly reflected (not through the second reflective layer  110 B 1 ) to the second condensing lens  130 B by the fluorescent particles  110 B 4 . In addition, the eighth part L 52  that has not been converted by the fluorescent particles  110 B 4  could be reflected back the second wavelength conversion layer  110 B 3  by the second reflective layer  110 B 1  for increasing the probability of converting the light wavelength by the fluorescent particles  110 B 4 . The optical path of the converted light L 52   a  provided by the second light source  110 B is similar to or the same as the optical path of the second light L 2  (shown in  FIG.  1 B ) emitted by the second light source  110 B, and the similarities will not be repeated here. 
     In summary, although the wavelength of the fifth light L 5  emitted by the fifth light source  410 E is different from the first wavelength, the fifth light L 5  could be converted into the converted light L 51 a and the converted light L 52   a  having the first wavelength through the first wavelength conversion layer  110 A 3  and the second wavelength conversion layer  110 B 3  for increasing the amount of light which has the first wavelength and is traveled to the module from the light source module  400 . 
     In another embodiment, the first light source  110 A of  FIG.  4    could not emit the first light L 1  and/or the second light source  110 B could not emit the second light L 2 . Furthermore, the first light source  110 A could provide the converted light L 51   a  having the first wavelength (as if the first light source  110 A emits the converted light L 51   a ) through the first wavelength conversion layer  110 A 3  and the first reflective layer  110 A 1 , and/or the second light source  110 B could provide the converted light L 52   a  having the first wavelength (as if the second light source  110 B emits the converted light L 52   a ) through the second wavelength conversion layer  110 B 3  and the second reflective layer  110 B 1 . In such example, the first light source  110 A could omit the first light-emitting layer  110 A 2  and/or the second light source  11 B could omit the second light-emitting layer  110 B 2 , that is, the first light source  110 A includes the first wavelength conversion  110 A 3  disposed on the first reflective layer  110 A 1 , and the second light source  110 B includes the second wavelength conversion layer  110 B 3  disposed on the second reflective layer  110 B 1 . 
     In terms of light-splitting characteristics, as shown in  FIG.  4   , the first light-splitting element  420 A could reflect the first light L 1  and the second light L 2  (not shown in the  FIG.  4   ) having the first wavelength (for example, green light spectrum) and the fifth light L 5  having the third wavelength (for example, blue light spectrum) but allows the third light L 3  having the second wavelength (for example, red light spectrum) to travel through. The second light-splitting element  420 B could reflect the second light L 2  and the first light L 1  (not shown in  FIG.  4   ) having the first wavelength (for example, green light spectrum) and the fifth light L 5  having the third wavelength (for example, blue light spectrum) but allows the third light L 3  having the second wavelength (for example, red light spectrum) to travel through. The third light-splitting element  420 C could reflect the first light L 1  (not shown in  FIG.  4   ) and the second light L 2  (not shown in  FIG.  4   ) having the first wavelength (for example, green light spectrum) and the third light L 3  having the second wavelength (for example, red light spectrum), but allows the fourth light L 4  and the fifth light L 5  having the third wavelength (for example, blue light spectrum) to travel through. 
     Referring to  FIG.  5   ,  FIG.  5    shows a schematic diagram of the optical path of a light source module  500  according to another embodiment of the present invention. The light source module  500  includes the first light source  110 A, the second light source  1106 , a third light source  410 C, a fourth light source  410 D, a fifth light source  410 E, a first light-splitting element  420 A, a second light-splitting element  420 B, a third light-splitting element  420 C, and at least one condensing lens (for example, the first condensing lens  130 A, the second condensing lens  1306 , the third condensing lens  130 C, the fourth condensing lens  130 D, the fifth condensing lens  330 E), the first reflective element  240 A, and the second reflective element  240 B. 
     The light source module  500  of the embodiment of the present invention has the features similar to or the same as that of the light source module  400  except that the light source module  500  further includes the first reflective element  240 A and the second reflective element  240 B. The arrangement and/or functions of the first reflective element  240 A and the second reflective element  240 B are similar to or the same as that of the first reflective element  240 A and the second reflective element  240 B of the light source module  200 , and the similarities will not be repeated here. 
     As shown in  FIG.  5   , the seventh part L 51  of the fifth light L 5  is incident to the first light source  110 A through the third light-splitting element  420 C and the first light-splitting element  420 A. The seventh part L 51  is converted into the converted light L 51   a  having the first wavelength by the first wavelength conversion layer  110 A 3  of the first light source  110 A and reflected to the first condensing lens  130 A through the first reflective layer  110 A 1 . The optical path of the converted light L 51   a  reflected from the first light source  110 A is similar to or the same as the optical path of the first part L 11  and the second part L 12  of  FIG.  3   , and the similarities will not be repeated here. Similarly, the eighth part L 52  of the fifth light L 5  is incident to the second light source  1106  through the third light-splitting element  420 C and the second light-splitting element  420 B. The eighth part L 52  is converted into the converted light L 52   a  having the first wavelength by the second wavelength conversion layer  110 B 3  of the second light source  110 B, and reflected to the second condensing lens  130 B through the second reflective layer  110 B 1 . The optical path of the converted light L 52   a  reflected from the second light source  110 B is similar to or the same as the optical path of the third part L 21  and the fourth part L 22  of  FIG.  3   , and the similarities will not be repeated here. 
     Referring to  FIG.  6   ,  FIG.  6    shows a schematic diagram of the optical path of a light source module  600  according to another embodiment of the present invention. The light source module  600  includes the first light source  110 A, the second light source  1106 , the third light source  410 C, the fourth light source  110 D, the fifth light source  410 E, the first light-splitting element  420 A, the second light-splitting element  420 B, the third light-splitting element  420 C, at least one condensing lens (for example, the first condensing lens  130 A, the second condensing lens  130 B, the third condensing lens  130 C, the fourth condensing lens  130 D, the fifth condensing lens  330 E) and a relay lens  650 . 
     The light source module  600  has the technical features same as or similar to that of the aforementioned light source module  400  except that the light source module  600  further includes the relay lens  650 . The relay lens  650  could make the modules that travel a longer path also get better lighting efficiency. 
     In summary, the embodiment of the present disclosure provides a light source module including at least one light-splitting element and two light sources, wherein the two light sources are oppositely disposed and/or their optical axes are substantially parallel. At least one light-splitting element is disposed between the two light sources, so that the optical path length of light emitted by the two light sources could be shortened. Due to two light sources having the same wavelength and oppositely disposed, it could increase the brightness of the light source module. In addition, the light source herein is, for example, a light source that could actively emit light (including the semiconductor epitaxial layer), such as a light-emitting diode or a laser light source, but it could also be a light source that converts the wavelength of an external light and reflects it to be emitted (for example, without the light-emitting layer). 
     It will be apparent to those skilled in the art that various modifications and variations could be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.