Light source module

Abstract

The invention discloses a light source module which comprises a light-emitting element, a light guide pipe, a wave plate and a polaroid. The light-emitting element emits a light beam. The light pipe includes a concave curved surface, an output surface, a first convex surface, and a second convex surface. The concave curved surface faces the light emitting element. The output surface is opposite the concave curved surface. The first convex surface connects the concave curved surface with the output surface. A second convex surface connects the concave curved surface and the output surface and is opposite the first convex surface, where the light beam enters the light pipe through the concave curved surface and exits the light pipe through the output surface. The wave plate is disposed on a path of the light beam from the output surface. The polarizer is disposed on a path of the light beam from the wave plate.

Description

Technical Field

[0001] The present invention relates to an optical module, and in particular to a light source module. Background Art

[0002] With the development of display technology, projectors have been created, which produce images that are relatively large for projectors. Liquid-crystal-on-silicon (LCOS) panels are key components in projectors, converting the illumination beam into the image beam. However, LCOS panels are not self-luminous and therefore require a light source to illuminate them.

[0003] In traditional projectors, a polarizing beam splitter (PBS) is placed in front of the LCOS panel to filter out beams with unwanted polarization directions. However, the PBS takes up a large space in front of the LCOS panel, making the optical system too bulky. Furthermore, when an unpolarized illumination beam reaches the PBS, only half of the illumination beam is transmitted to the LCOS panel, resulting in light loss. Summary of the Invention

[0004] The present invention is directed to a light source module, which can reduce the volume of an optical system and reduce light loss.

[0005] One embodiment of the present invention provides a light source module comprising a light emitting element, a light pipe, a wave plate, and a polarizer. The light emitting element is configured to emit a light beam. The light pipe comprises a concavely curved surface, an output surface, a first convex surface, and a second convex surface. The concave curved surface faces the light emitting element. The output surface is opposite the concave curved surface. The first convex surface connects the concave curved surface to the output surface. The second convex surface connects the concave curved surface and the output surface and is opposite the first convex surface. The light beam enters the light pipe through the concave curved surface and exits the light pipe through the output surface. The wave plate is positioned in the path of the light beam from the output surface. The polarizer is positioned in the path of the light beam from the wave plate and is configured to allow a first portion of the light beam having a first polarization direction to pass through and reflect a second portion of the light beam having a second polarization direction. The second portion of the light beam passes through the wave plate and the output surface and reenters the light pipe. At least a portion of the second portion of the light beam is then reflected by at least one of the concave curved surface, the first convex surface, and the second convex surface, thereby returning to the wave plate and the polarizer.

[0006] In a light source module according to an embodiment of the present invention, a light pipe is used, which includes a concave curved surface, an output surface, a first convex surface, and a second convex surface. At least a portion of the second portion of the light beam is reflected by at least one of the concave curved surface, the first convex surface, and the second convex surface, thereby propagating past the reflective plate and the polarizer. Consequently, the light pipe recirculates light, reducing light loss. Furthermore, the use of the light pipe reduces the volume of the optical system, enabling a compact structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic cross-sectional view of a front-illuminated liquid crystal on silicon module according to an embodiment of the present invention;

[0008] Figure 2A yes Figure 1 a rectangular candela distribution of a light beam emitted by a light emitting element before passing through a concave curved surface;

[0009] Figure 2B yes Figure 1 Rectangular candela distribution of the light beam emitted by the light emitting element after passing through the concave curved surface;

[0010] Figure 3A and Figure 3B is a cross-sectional schematic diagram of a light source module according to another embodiment of the present invention, which respectively illustrates two possible paths of the second portion of the light beam;

[0011] Figure 4 FIG. 1 is a cross-sectional schematic diagram of a light source module according to another embodiment of the present invention. DETAILED DESCRIPTION

[0012] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0013] Figure 1 FIG is a cross-sectional view of a front-lit liquid-crystal-on-silicon module according to an embodiment of the present invention. Figure 1In this embodiment, the front-illuminated LCS module 200 includes a light source module 100, a waveguide 220, an LCS panel 230, and a polarizer 240. The light source module 100 includes a light-emitting element 110, a light pipe 120, a wave plate 150, and a polarizer 160. The light-emitting element 110 is used to emit a light beam 111. In this embodiment, the light-emitting element 110 includes a plurality of light-emitting diodes (LEDs) 112 and a window plate 114 disposed above the LEDs 112. The LEDs 112 can include multiple LEDs having multiple emission colors. For example, the LEDs 112 can include a red LED, a green LED, and a blue LED.

[0014] The light pipe 120 includes a concavely curved surface 124, an output surface 128, a first convex surface 122, and a second convex surface 126. The concavely curved surface 124 faces the light emitting element 110. The output surface 128 is opposite the concavely curved surface 124. In this embodiment, the output surface 128 is, for example, a planar surface. The first convex surface 122 connects the concavely curved surface 124 and the output surface 128. The second convex surface 126 connects the concavely curved surface 124 and the output surface 128 and is opposite the first convex surface 122. The light beam 111 enters the light pipe 120 through the concave curved surface 124 and exits the light pipe 120 through the output surface 128. In this embodiment, the light beam 111 emitted from the light emitting diode 112 passes through the window plate 114 and reaches the concave curved surface 124. The wave plate 150 is disposed in the path of the light beam 111 from the output surface 128. Polarizer 160 is disposed in the path of light beam 111 from wave plate 150 and is configured to allow a first portion 113 of light beam 111 having a first polarization direction P1 to pass therethrough, while reflecting a second portion 115 of light beam 111 having a second polarization direction. In this embodiment, the second polarization direction is perpendicular to the first polarization direction P1. Second portion 115 of light beam 111 passes through wave plate 150 and output surface 128 and re-enters light pipe 120. At least a portion of second portion 115 of light beam 111 is then reflected by at least one of concave curved surface 124, first convex surface 122, and second convex surface 126, thereby propagating back through wave plate 150 and polarizer 160. In this embodiment, wave plate 150 is a quarter wave plate. Since second portion 115 of light beam 111, returning to polarizer 160, passes through wave plate 150 twice, the polarization direction of second portion 115 of light beam 111 becomes the first polarization direction P1. Thus, the second portion 115 of the light beam 111 having the first polarization direction P1 passes through the polarizer 160 and is recycled, thereby reducing light loss in the light source module 100. In one embodiment, the light source module 100 can recycle 30% of the light.

[0015] In the light source module 100 of this embodiment, a light pipe 120 is employed, which includes a concave curved surface 124, an output surface 128, a first convex surface 122, and a second convex surface 126. At least a portion of the second portion 115 of the light beam 111 is reflected by at least one of the concave curved surface 124, the first convex surface 122, and the second convex surface 126, thereby propagating back to the wave plate 150 and the polarizer 160. Therefore, since the light pipe 120 recirculates light, light loss is reduced. Furthermore, the use of the light pipe 120 reduces the size of the optical system (e.g., the front-illuminated LCS module 200), resulting in a compact structure. Furthermore, in this embodiment, the light pipe 120 is configured to reflect (e.g., via the concave curved surface 124) at least a portion of the second portion 115 of the light beam 111, preventing it from irradiating the light-emitting element 110. This prevents this portion of the second portion 115 of the light beam 111 from being absorbed by the light-emitting element 110, further reducing light loss.

[0016] In one embodiment, the polarizer 160 is, for example, a wire grid polarizer film. The waveguide 220 has a first surface 222, a second surface 224 opposite the first surface 222, and a light entrance surface 226 connecting the first and second surfaces 222 and 224. The light beam 111 from the polarizer 160 enters the waveguide 220 through the light entrance surface 226. The liquid crystal on silicon panel 230 is disposed below the second surface 224 and is configured to convert the light beam 111 having a first polarization direction P1 into a polarized image beam 231 having a second polarization direction P2. The polarizer 240 is disposed on the first surface 222 and is configured to allow the polarized image beam 231 having the second polarization direction P2 to pass therethrough. The polarized image beam 231 from the liquid crystal on silicon panel 230 passes through the second surface 224, the first surface 222, and the polarizer 240 in sequence. In this embodiment, the first polarization direction P1 is perpendicular to the second polarization direction P2.

[0017] In this embodiment, the front-illuminated LCOS module 200 further includes a plurality of micro-mirrors 250 arranged at intervals along the first surface 222, and configured to reflect the light beam 111 toward the LCOS panel 230. In one embodiment, each micro-mirror 250 is a polarizing beam splitter film that reflects the light beam 111 having a first polarization direction P1 and allows the polarized image beam 231 having a second polarization direction P2 to pass therethrough.

[0018] In this embodiment, the concave curved surface 124, the first convex surface 122, and the second convex surface 126 can be described by a one-dimensional polynomial. However, in another embodiment, the concave curved surface 124, the first convex surface 122, and the second convex surface 126 can be described by a two-dimensional polynomial. Alternatively, the concave curved surface 124, the first convex surface 122, and the second convex surface 126 can be described by mesh data. In this embodiment, the refractive index of the light pipe 120 falls within the range of 1.3 to 2.3. In addition, in this embodiment, the light source module 100 further includes at least one coupling lens ( Figure 1 1 and 2 , two coupling lenses 130 and 140 are exemplarily shown, disposed between the light pipe 120 and the wave plate 150 to couple the light beam 111 to the wave plate 150. For example, each of the coupling lenses 130 and 140 is a lens array. However, in other embodiments, each of the coupling lenses 130 and 140 can be a single lens.

[0019] Figure 2A yes Figure 1 The rectangular candela (cd) distribution diagram of the light beam emitted by the light emitting element before passing through the concave curved surface, Figure 2B yes Figure 1 The rectangular candela distribution diagram of the light beam emitted by the light emitting element after passing through the concave curved surface. Figure 2A and Figure 2B In the figure, the curves marked with 0.0, 45.0, 90.0 and 135.0 represent curves located in planes with directions of 0.0, 45.0, 90.0 and 135.0 degrees, wherein each plane contains the optical axis of the light emitting element 110 and the plane with a direction of 0.0 degree is Figure 1 From the drawing. Figure 2A and Figure 2B It can be seen that the light pipe 120 is used to convert the light beam 111 emitted by the light emitting element 110 from a Lambertian profile to a profile with two or more intensity peaks ( Figure 2B Two intensity peaks are shown exemplarily in FIG).

[0020] Figure 3A and Figure 3B is a cross-sectional schematic diagram of a light source module according to another embodiment of the present invention, which shows two possible paths of the second part of the light beam. Figure 3A and Figure 3B , the light source module 100a and Figure 1The light source module 100a is similar to the light source module 100 in FIG. 1 , with the following main differences. In this embodiment, the light source module 100a further includes a first reflector 172 configured to face the first convex surface 122 and a second reflector 174 configured to face the second convex surface 126. The second portion 115 of the light beam 111 reflected by the polarizer 160 may have multiple possible circulation paths. Two paths are used as two examples below, such as Figure 3A and Figure 3B shown.

[0021] refer to Figure 3A The second portion 115 of the light beam 111 reflected by the polarizer 160 is sequentially reflected by the first convex surface 122, reflected by the concave curved surface 124, refracted by the first convex surface 122, diffusely reflected by the carrier 50 carrying the light emitting element 110, refracted by the first convex surface 122, refracted twice by the concave curved surface 124, reflected by the second convex surface 126, and passes through the polarizer 160. Figure 3B , the second portion 115 of the light beam 111 reflected by the polarizer 160 is sequentially refracted by the first convex surface 122, reflected by the first reflector 172, refracted by the first convex surface 122, refracted twice by the concave curved surface 124, refracted by the second convex surface 126, reflected by the second reflector 174, refracted by the second convex surface 126, and passes through the polarizer 160. In other possible circulation paths, the second portion 115 of the light beam 111 may be reflected or refracted multiple times by the surface of the light pipe 120, the first reflector 172, or the second reflector 174.

[0022] Figure 4 FIG is a cross-sectional view of a light source module according to another embodiment of the present invention. Figure 4 In this embodiment, the light source module 100b and Figure 1 The light source module 100 of the embodiment is similar to the light source module 100 of the embodiment, with the main differences being as follows: In the light source module 100 of the embodiment, the output surface 128b of the light pipe 120b is a concave surface, so that the light pipe 120b is a hollow tube.

[0023] In summary, the light source module of the embodiments of the present invention utilizes a light pipe comprising a concave curved surface, an output surface, a first convex surface, and a second convex surface. At least a portion of the second portion of the light beam is reflected by at least one of the concave curved surface, the first convex surface, and the second convex surface, thereby propagating past the reflector plate and the polarizer. Consequently, light loss is reduced by the light pipe's light recycling, and the optical system's volume is reduced, resulting in a compact structure.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light source module, characterized in that: include: a light-emitting element for emitting a light beam; The light guide includes: a concave curved surface facing the light emitting element; an output surface opposite the concave curved surface; a first convex surface connecting the concave curved surface and the output surface; and a second convex surface connecting the concave curved surface and the output surface and opposite to the first convex surface, wherein the light beam enters the light pipe through the concave curved surface and exits the light pipe through the output surface; a wave plate disposed in a path of the light beam from the output surface; and a polarizer disposed on the path of the light beam from the wave plate and configured to allow a first portion of the light beam having a first polarization direction to pass therethrough and reflect a second portion of the light beam having a second polarization direction; The second portion of the light beam passes through the wave plate and the output surface and enters the light pipe again, and then at least a portion of the second portion of the light beam is reflected by at least one of the concave curved surface, the first convex surface, and the second convex surface, thereby propagating back to the wave plate and the polarizer.

2. The light source module according to claim 1, wherein: The concave curved surface, the first convex surface, and the second convex surface are described by a one-dimensional polynomial.

3. The light source module according to claim 1, wherein: The concave curved surface, the first convex surface, and the second convex surface are described by two-dimensional polynomials.

4. The light source module according to claim 1, wherein: The light pipe is used to convert the light beam emitted by the light emitting element from a Lambertian distribution to a distribution with two or more intensity peaks.

5. The light source module according to claim 1, wherein: The light pipe is configured to reflect at least a portion of the second portion of the light beam to prevent the second portion from irradiating the light emitting element.

6. The light source module according to claim 1, wherein: The refractive index of the light pipe is in a range of 1.3 to 2.

3.

7. The light source module according to claim 1, wherein: The output surface is a concave surface, making the light guide a hollow tube.

8. The light source module according to claim 1, wherein: Also included is a first reflector configured to face the first convex surface and a second reflector configured to face the second convex surface.

9. The light source module according to claim 1, wherein: The invention also includes at least one coupling lens, which is arranged between the light pipe and the wave plate.

10. The light source module according to claim 1, wherein: The coupling lens is a lens array.

11. The light source module according to claim 1, wherein: The wave plate is a quarter wave plate.

12. The light source module according to claim 1, wherein: The light emitting element includes a plurality of light emitting diodes.

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