Patent Publication Number: US-2023135388-A1

Title: Light source module

Description:
This application claims the benefit of Taiwan application Serial No. 110140447, 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 first light-splitting element in a second optical path direction substantially perpendicular to the first optical path direction. The third light source is configured to emit a third light having a second wavelength to the first light-splitting element and the second light-splitting element in a third optical path direction, wherein the third optical path direction is opposite to the second optical path direction, and the second wavelength is different from the first wavelength. The first light source includes a first reflection layer, the second light source includes a second reflection layer, and the first reflection layer and the second reflection 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 an optical path of a light source module according to another embodiment of the present invention; 
         FIGS.  3 A and  3 B  show schematic diagrams of optical paths of a light source module according to another embodiment of the present invention; 
         FIG.  4    shows a schematic diagram of an optical path of a light source module according to another embodiment of the present invention; and 
         FIG.  5    shows a schematic diagram of an 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, a fourth light-splitting element  120 D and at least one condensing lens (for example, a first condensing lens  130 A, a second condensing lens  130 B, a third condensing lens  130 C and a fourth condensing lens  130 D). 
     As shown in  FIG.  1 A , the first light source  110 A is configured for emitting 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 the first optical path direction P 1 . As shown in  FIG.  1 B , the second light source  110 B is configured to emit the 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  substantially perpendicular to the first optical path direction P 1 . The third light source  110 C is configured for emitting a third light L 3  having a second wavelength to travel in a third optical path direction P 3  opposite to (or reverse to) the second optical path direction P 2 , wherein the second wavelength is different from the first wavelength. The first light source  110 A includes a first reflection layer  110 A 1 , and the second light source  110 B includes a second reflection layer  110 B 1 . The first reflection layer  110 A 1  and the second reflection layer  110 B 1  are configured to reflect light. For example, the first reflection layer  110 A 1  reflects a portion of the second light L 2  (for example, the fourth part L 22 , described later), while the second reflective layer  110 B 1  reflects a portion of the first light L 1  (for example, the second part L 12 , described later). As a result, by the configuration of the first light-splitting element  120 A, an optical path length of the first light L 1  could be shortened, and by the configuration of the second light-splitting element  120 B, an optical path length of the second light L 2  could be shortened. 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 adjacent to each other. The first light source  110 A is disposed in a first center line (or optical axis) S 1 , for example, the first center line S 1  passes through a center of the first light source  110 A. The first light L 1  emitted by the first light source  110 A is divided into the first part L 11  and the second part L 12  relative to the first center line S 1 . The first part L 11  is incident to a module  10 , on a side of the first center line S 1 , in the first optical path direction P 1  through the fourth light-splitting element  120 D, wherein the module  10  is, for example, an illuminating module or an imaging module. The second part L 12  is incident, on the other side of the first center line S 1 , to the first light-splitting element  120 A in the first optical path direction P 1 , is incident to the second light source  110 B through the first light-splitting element  120 A, and is reflected by the second reflection 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 second reflected part L 12 ′ is similar 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 source  110 B is disposed in the second center line S 2 , for example, the second center line S 2  passes through a center of the second light source  110 B. The second light L 2  emitted by the second light source  110 B is divided into the third part L 21  and the fourth part L 22  relative to the second center line S 2 . The third part L 21  is incident, on a side of the second center line S 2 , to the fourth light-splitting element  120 D in the second optical path direction P 2  and is incident to the module  10  through the fourth light-splitting element  120 D and the second light-splitting element  120 B. The fourth part L 22  is incident, on the other side of the second center line S 2 , to the first light-splitting element  120 A in the second optical path direction P 2 , is incident to the first light source  110 A through the first light-splitting element  120 A, and then is reflected by the first reflection 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 fourth reflected part L 22 ′ is similar or the same as the optical path of the first light L 1  of the first light source  110 A (as shown in  FIG.  1 A ). 
     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 first light-splitting element  120 A 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.  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, for example, 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  (for example, blue light) into the first light L 1  (for example, green light) having 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-splitting element  120 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, for example, 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  (for example, blue light) into the second light L 2  (for example, 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 in the third center line S 3 . For example, the third center line S 3  passes through the center of the third light source  110 C. The third light L 3  emitted by the third light source  110 C is divided into a fifth part L 31  and a sixth part L 32  relative to the third center line S 3 . The fifth part L 31  is incident, on a side of the third center line S 3 , to the third light-splitting element  120 C in the third optical path direction P 3 , and is incident to the module  10  through the third light-splitting element  120 C, the second light-splitting element  120 B and the fourth light-splitting element  120 D, while the sixth part L 32  is incident, on the other side of the third center line S 3 , to the third light-splitting element  120 C in the third optical path direction P 3 , and is incident to the module  10  through the third light-splitting element  120 C, the first light-splitting element  120 A and the second light-splitting element  120 B. In addition, the third center line S 3  and the second center line S 2  are substantially coincident with each other, but they could also be staggered. 
     As shown in  FIG.  1 A , the fourth light source  110 D is configured to emit a fourth light L 4  having a third wavelength, wherein the fourth light L 4  is incident to the module  10  through the third light-splitting element  120 C, the first light-splitting element  120 A and the second light-splitting element  120 B in the first optical path direction P 1 , wherein the third wavelength is different from the first wavelength and the second wavelength. In an embodiment, the second wavelength ranges, for example, between 620 nm and 750 nm, and the third wavelength ranges, for example, between 450 nm and 475 nm. Specifically, the third light L 3  is, for example, red light, and the fourth light L 4  is, for example, blue light. 
     As shown in  FIG.  1 A , the fourth light source  110 D is disposed in a fourth center line S 4 , for example, the fourth center line S 4  passes through a center of the fourth light source  110 D. The fourth light L 4  emitted by the fourth light source  110 D is divided into a seventh part L 41  and an eighth part L 42  relative to the fourth center line S 4 , and the seventh part L 41  is incident, on a side of the fourth center line S 4 , to third light-splitting element  120 C in the first optical path direction P 1  and is incident to the module  10  through the third light-splitting element  120 C, the first light-splitting element  120 A and the second light-splitting element  120 B, while the eighth part L 42  is incident, on the other side of the fourth center line S 4 , to the third light-splitting element  120 C in the first optical path direction P 1  and is incident to the module  10  through the third light-splitting element  120 C, the second light-splitting element  120 B and the fourth light-splitting element  120 D. 
     As shown in  FIG.  1 A , the first light-splitting element  120 A and the fourth light-splitting element  120 D are disposed opposite to the first light source  110 A. The first light-splitting element  120 A and the fourth light-splitting element  120 D are disposed on opposite sides of the first center line S 1 . As a result, the first part L 11  and the second part L 12  of the first light L 1  emitted by the first light source  110 A are incident to the light-splitting element  120 D and the first light-splitting element  120 A respectively. 
     As shown in  FIG.  1 A , the first light-splitting element  120 A and the fourth light-splitting element  120 D are disposed opposite to the third light source  110 C. The first light-splitting element  120 A and the fourth light-splitting element  120 D are respectively disposed on opposite sides of the third center line S 3 , and the fifth part L 31  and the sixth part L 32  of the third light L 3  are incident to the fourth light-splitting element  120 D and the first light-splitting element  120 A respectively and is reflected to the module  10  by the fourth light-splitting element  120 D and the first light-splitting element  120 A. 
     As shown in  FIG.  1 A , the first light-splitting element  120 A and the fourth light-splitting element  120 D are respectively disposed on opposite sides of the third center line S 3 . As a result, the seventh part L 41  of the fourth light L 4  could be reflected to the first light-splitting element  120 A by a portion of the third light-splitting element  120 C which is located on a side of the third center line S 3 , while the eighth part L 42  could be reflected to the fourth light-splitting element  120 D by a portion of the third light-splitting element  120 C which is located on the other side of the third center line S 3 . Then, the seventh part L 41  and the eighth part L 42  could be reflected to the module  10  through the first light-splitting element  120 A and the fourth light-splitting element  120 D 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 third center line S 3  passes through the third light-splitting element  120 C, for example, the third center line S 3  passes through a center of the third light-splitting element  120 C. As a result, the third light L 3  emitted by the third light source  110 C could entirely travel through 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 fourth center line S 4  passes through the third light-splitting element  120 C, for example, the fourth center line S 4  passes through the center of the third light-splitting element  120 C. As a result, the fourth light L 4  emitted by the fourth light source  110 D could be entirely reflected to the first light-splitting element  120 A and the fourth light-splitting element  120 D by the third light-splitting element  120 C. 
     As shown in  FIG.  1 A , the first light-splitting element  120 A, the second light-splitting element  120 B and the third light-splitting element  120 C could be connected to each other. However, in another embodiment, any two of the first light-splitting element  120 A, the second light-splitting element  120 B and the third light-splitting element  120 C could be connected to each other. Alternatively, the first light-splitting element  120 A, the second light-splitting element  120 B and the third light-splitting element  120 C could be disposed separately. 
     In terms of the arrangement position of the light-splitting element, as shown in  FIG.  1 A , an angle A 1  of the first light-splitting element  120 A relative to a horizontal reference line is, for example, 45 degrees. Similarly, the angle of the others of the light-splitting elements relative to the horizontal reference line is also, for example, 45 degrees. 
     The light-splitting element herein is, for example, a dichroic light-splitting element. In terms of light splitting characteristics, as shown in  FIGS.  1 A and  1 B , the first light-splitting element  120 A could reflect the first light L 1  and the second light L 2  having the first wavelength (for example, green light spectrum), the third light L 3  having the second wavelength (for example, red light spectrum) and the fourth light L 4  having the third wavelength (for example, blue light spectrum). The second light-splitting element  120 B could reflect the second light L 2  having the first wavelength (for example, green light spectrum) but allow the third light L 3  having the second wavelength (for example, the red light spectrum) and the third light L 3  having the third wavelength (for example, the blue light spectrum) of the fourth light L 4  to travel through. The third light-splitting element  120 C could reflect the fourth light L 4  having the third wavelength (for example, blue light spectrum) but allow the third light L 3  having the second wavelength (for example, red light spectrum) to travel through. The fourth light-splitting element  120 D could reflect the third light L 3  having the second wavelength (for example, red light spectrum) and the fourth light L 4  having the third wavelength (for example, blue light spectrum) but allows the second light L 2  having he first wavelength (for example, green 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  130 B is disposed opposite to the second phase light source  110 B. The second condensing lens  130 B 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  130 B so that the third part L 21  and the fourth part L 22  incident to the second condensing lens  130 B 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 third center line S 3 . For example, the third center line S 3  passes through the 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 third center line S 3 . 
     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 fourth center line S 4 . For example, the fourth center line S 4  passes through the 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 fourth center line S 4 . 
     Referring to  FIG.  2   ,  FIG.  2    shows a schematic diagram of an 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  110 B, the third light source  110 C, the fourth light source  110 D, a first light-splitting element  220 A, a second light-splitting element  220 B, a third light-splitting element  220 C, a fourth light-splitting element  220 D and 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 and the fourth condensing lens  130 D), 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, for example reflective mirror. 
     As shown in  FIG.  2   , the first reflector  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  220 A in the first optical path direction P 1  and then is incident to the module  10  through the first light-splitting element  220 A. 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 is reflected back to 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  220 B and the third light-splitting element  220 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 is 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 source  110 B is disposed in the second center line S 2 . The second light-splitting element  220 B and the second reflective element  240 B are respectively disposed on opposite two sides of the second center line S 2 . 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  220 B 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 . 
     In terms of light-splitting characteristics, as shown in  FIG.  2   , the first light-splitting element  220 A could reflect the third light L 3  having the second wavelength (for example, red light spectrum) and the fourth light L 4  having the third wavelength (for example, blue light spectrum), but allows the first light L 1  having the first wavelength (for example, green light spectrum) to travel through. The second light-splitting element  220 B could reflect the second light L 2  having the first wavelength (for example, green light spectrum). The third light-splitting element  120 C could reflect the fourth light L 4  having the third wavelength (for example, blue light spectrum) but allow the third light L 3  having the second wavelength (for example, red light spectrum) to travel through. The fourth light-splitting element  120 D could reflect the third light L 3  having the second wavelength (for example, red light spectrum) and the fourth light L 4  having the third wavelength (for example, blue light spectrum) but allows the second light L 2  having the first wavelength (for example, green light spectrum) to travel through. 
     Referring to  FIGS.  3 A and  3 B ,  FIGS.  3 A and  3 B  show schematic diagrams of optical paths 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, the fourth light source  110 D, a first light-splitting element  320 A, a second light-splitting element  320 B, a third light-splitting element  320 C, a fourth light-splitting element  320 D and 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 and the fourth condensing lens  130 D). 
     As shown in  FIG.  3 A , the first light source  110 A is disposed in the first center line S 1 , and the first center line S 1  passes through a center of the first light-splitting element  320 A. The first light L 1  emitted by the first light source  110 A is divided into the first part L 11  and a second part L 12  relative to the first center line S 1 , wherein the first part L 11  is incident, on a side of the first center line S 1 , to the first light-splitting element  320 A in the first optical path direction P 1  and is incident to the module  10  through the first light-splitting element  320 A and the third light-splitting element  320 C, while the second part L 12  is incident, on the other side of the first center line S 1 , to the first light-splitting element  320 A in the first optical path direction P 1 , incident to the second light source  110 B through the first light-splitting element  320 A and the fourth light-splitting element  320 D and then reflected by the second reflection 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 second reflected part L 12 ′ is similar or the same as the optical path of the second light L 2  of the second light source  110 B (as shown in  FIG.  3 B ). 
     As shown in  FIG.  3 B , the second light source  110 B is disposed in the second center line S 2 , and the second center line S 2  passes through the center of the second light source  110 B. The second light L 2  emitted by the second light source  110 B is divided into the third part L 21  and the fourth part L 22  relative to the second center line S 2 , wherein the third part L 21  is incident, on a side of the second center line S 2 , to the second light-splitting element  320 B in the second optical path direction P 2  and incident to the first module  10  through the second light-splitting element  320 B and the fourth light-splitting element  320 D, while the fourth part L 22  is incident, on the other side of the second center line S 2 , to the first light-splitting element  320 A in the second optical path direction P 2 , incident to the first light source  110 A through the first light-splitting element  320 A and then 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 fourth reflected part L 22 ′ is similar or the same as the optical path of the first light L 1  of the first light source  110 A (as shown in  FIG.  3 A ). 
     As shown in  FIG.  3 A , the fourth light source  110 D emits the fourth light L 4  to the third light-splitting element  320 C and the second light-splitting element  320 B in the fourth optical path direction P 4  opposite to the first optical path direction P 1 . 
     As shown in  FIG.  3 A , the first light-splitting element  320 A is disposed relative to the first light source  110 A. The first center line S 1  passes through the first light-splitting element  320 A, for example, the first center line S 1  passes through the center of the first light-splitting element  320 A. As a result, the first light L 1  could be entirely incident to the first light-splitting element  320 A. Similarly, the first light-splitting element  320 A is disposed opposite to the third light source  110 C. The third center line S 3  passes through the first light-splitting element  320 A, for example, the third center line S 3  passes through the center of the first light-splitting element  320 A. As a result, the third light L 3  could be entirely incident to the first light-splitting element  320 A. 
     As shown in  FIG.  3 B , the second light-splitting element  320 B and the fourth light-splitting element  320 D are respectively disposed on two opposite sides of the second center line S 2 . As a result, the third part L 21  and the fourth part L 22  of the second light L 2  could be incident to the second light-splitting element  320 B and the fourth light-splitting element  320 D respectively. In addition, the second light-splitting element  320 B and the third light-splitting element  320 C are respectively disposed on two opposite sides of the fourth center line S 4 . As a result, the seventh part L 41  and the eighth part L 42  of the fourth light L 4  could be incident to the third light-splitting element  320 C and the second light-splitting element  320 B respectively. In addition, the third light-splitting element  320 C and the fourth light-splitting element  320 D are respectively disposed on two opposite sides of the third center line S 3 . As a result, the fifth part L 31  and the sixth part L 32  of the third light L 3  could be incident to the module  10  through the fourth light-splitting element  320 D and the third light-splitting element  320 C respectively. 
     In terms of light-splitting characteristics, as shown in  FIG.  3 A , the first light-splitting element  320 A could reflect the first light L 1  having the first wavelength (for example, green light spectrum) and the second light L 2  having the first wavelength but allow the third light L 3  having the second wavelength (for example, red light spectrum) to travel through. The second light-splitting element  320 B could reflect the second light L 2  having the first wavelength (for example, green light spectrum) but allow the fourth light L 4  having the third wavelength (for example, blue light spectrum) to travel through. The third light-splitting element  320 C could reflect the third light L 3  having the second wavelength (for example, the red light spectrum) and the first light L 1  having the first wavelength (the green light spectrum) but allow the fourth light L 4  having the third wavelength (for example, the blue light spectrum) to travel through. The fourth light-splitting element  320 D could reflect the third light L 3  having the second wavelength (for example, the red light spectrum) but allow the second light L 2  having the first wavelength (for example, the green light spectrum) and the fourth light L 4  having the third wavelength (for example, the blue light spectrum) to travel through. 
     Referring to  FIG.  4   ,  FIG.  4    shows a schematic diagram of an optical path of a light source module  400  according to another embodiment of the present invention. The light source module  400  includes the first light source  110 A, the second light source  110 B, the third light source  110 C, the fourth light source  110 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, a fourth light-splitting element  420 D, a fifth light-splitting element  420 E and 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 and a fifth condensing lens  430 E). Although not shown, the light source module  400  further includes an optical path, during operation, including 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  has the features similar or the same as that of the light source module  300  expect that the light source module  400  further includes the fifth light source  410 E, the fifth light-splitting element  420 E and the fifth condensing lens  430 E. 
     The fifth light source  410 E could emit a fifth light L 5  having the third wavelength to the first light source  110 A through the first light-splitting element  420 A and to the second light source  110 B through the fifth light-splitting element  420 E. In the present embodiment, the fifth light L 5  and the fourth light L 4  are, for example, blue light, and the third light L 3  is, for example, red light. 
     The fifth light source  410 E is disposed in the fifth center line S 5 , for example, the fifth center line S 5  passes through a center of the fifth light source  410 E. The fifth light L 5  is divided into a ninth part L 51  and a tenth part L 52  relative to the fifth center line S 5 . The ninth part L 51  is incident to the first light source  110 A through the fifth condensing mirror  430 E, the first light-splitting element  420 A and the first condensing mirror  130 A in sequence. After the ninth 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 mirror  130 A by the first reflective layer  110 A 1 , and another portion of the converted light is L 51   a  is emitted to the first condensing lens  130 A from the fluorescent particles  110 A 4 . In addition, the ninth 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  to increase the probability of the wavelength of light being converted 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 or the same as the optical path of the first light L 1  emitted by the first light source  110 A (the first light L 1  is shown in  FIG.  3 A ), and the similarities will not be repeated here. Similarly, after the tenth part L 52  is converted into a 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, a portion of the converted light L 52   a  is reflected to the second condensing lens mirror  130 B by the second reflection layer  110 B 1 , and another portion of the converted light L 52   a  could be directly emitted to the second condensing lens  130 B from the fluorescent particles  110 B 4 . In addition, the tenth part L 52  that has not been converted by the fluorescent particles  110 B 4  could be reflected by the second reflective layer  110 B 1  back the second wavelength conversion layer  110 B 3  to increase the probability of the wavelength of light being converted 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 or the same as the optical path of the second light L 2  emitted by the second light source  110 B (The second light L 2  is shown in  FIG.  1 B ), and the similarities will not be repeated here. 
     To sum up, 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 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  to increase the amount of light which has the first wavelength and is traveled to the module  10  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 is configured to 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) but allow the third light L 3  having the second wavelength (for example, red light spectrum) and the fifth light L 5  having the third wavelength (for example, blue light spectrum) to travel through. The second light-splitting element  420 B is configured to reflect the second light L 2  (not shown in  FIG.  4   ) having the first wavelength (for example, green light spectrum) but allow the fourth light L 4  having the third wavelength (for example, blue light spectrum) to travel through. The third light-splitting element  420 C is configured to reflect the third light L 3  having the second wavelength (for example, red light spectrum) but allow the fourth light L 4  having the third wavelength (for example, blue light spectrum) to travel through. The fourth light-splitting element  420 D is configured to reflect the third light L 3  having the second wavelength (for example, red light spectrum) but allow the fourth light L 4  having the third wavelength (for example, blue light spectrum) to travel through and allow the fourth light L 4  having the third wavelength (for example, blue light spectrum) and the second light L 2  (not shown in  FIG.  4   ) having the first wavelength (for example, green light spectrum) to travel through. The fifth light-splitting element  420 E is configured to reflect the fifth light L 5  having the third wavelength (for example, blue light spectrum) and the first light L 1  and the second light L 2  (not shown in  FIG.  4   ) having the first wavelength (for example, green light spectrum) but allow the third light L 3  having the second wavelength (for example, red light spectrum) and the fifth light L 5  having the third wavelength (for example, blue light spectrum) to travel through. 
     In addition, the fifth condensing lens  430 E is disposed opposite to the fifth light source  410 E. The fifth condensing mirror  430 E is disposed in the fifth center line S 5 , for example, the fifth central line S 5  passes through a center of the fifth condensing mirror  430 E, so that the ninth part L 51  and the tenth part L 52  incident to of the fifth condensing lens  430 E have substantially the same amount of light relative to the fifth center line S 5 . 
     Referring to  FIG.  5   ,  FIG.  5    shows a schematic diagram of an 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  110 B, the third light source  110 C, the fourth light source  110 D, the first light-splitting element  220 A, the second light-splitting element  220 B, the third light-splitting element  120 C, the fourth light-splitting element  120 D, 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, and the fourth condensing lens  130 D), the first reflective element  240 A and the second reflective element  240 B. 
     The light source module  500  has the technical features same as or similar to that of the aforementioned light source module  200  except that the light source module  500  includes a relay lens  550 . The relay lens  550  could make the light in modules that travels a longer optical 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 disposed adjacent to each other and/or their optical axes are substantially perpendicular. 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 disposed on adjacent sides, 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.