Projection device

Abstract

The invention provides a projection device which comprises a light source device which comprises a light source, a light splitting element, a quarter-wave plate and a reflecting element. The light source is used for emitting a lighting beam, the lighting beam has at least two different colored lights, and the lighting beam has a first linear polarization direction. The light splitting element, the quarter-wave plate and the reflecting element are located on a transmission path of the illumination light beam. The illumination light beam sequentially enters the quarter-wave plate and the reflecting element after passing through the light splitting element, and sequentially passes through the quarter-wave plate and the light splitting element after being reflected by the reflecting element. When the illumination light beam passes through the quarter-wave plate through the light splitting element, the illumination light beam has a second linear polarization direction, and the first linear polarization direction is perpendicular to the second linear polarization direction.

Description

Technical Field

[0001] The present invention relates to a projection device. Background Art

[0002] In projection systems, high-quality projected images have a wide range of applications. Therefore, efficiently generating high-quality, multi-color light while simultaneously miniaturizing the system and reducing costs has become a key issue in this technology. Summary of the Invention

[0003] The purpose of the present invention is to solve the defects of the current projection system that it is too large in size and has a high cost.

[0004] The present invention provides a projection device, which includes: a light source device, wherein the light source device includes: a light source, a beam splitter, a quarter wave plate, and a reflective element, wherein:

[0005] The light source is used to emit an illumination beam having at least two different colors of light and a first linear polarization direction. The beam splitter, the quarter-wave plate, and the reflective element are located on a transmission path of the illumination beam.

[0006] After passing through the beam splitter, the illumination light beam sequentially enters the quarter-wave plate and the reflective element, and after being reflected by the reflective element, sequentially passes through the quarter-wave plate and the beam splitter. After passing through the beam splitter and the quarter-wave plate, the illumination light beam has a second linear polarization direction, and the first linear polarization direction is perpendicular to the second linear polarization direction.

[0007] In a preferred embodiment, the beam splitter element is used to reflect the illumination light beam having the first linear polarization direction and to allow the illumination light beam having the second linear polarization direction to pass through; the light source and the reflective element are located on the same side of the beam splitter element.

[0008] In a preferred embodiment, the beam splitter element is used to allow the illumination light beam with a first linear polarization direction to pass through, and to reflect the illumination light beam with a second linear polarization direction; the light source and the reflective element are respectively located on two sides of the beam splitter element.

[0009] In a preferred embodiment, the system further comprises: a homogenizing element disposed on the transmission path of the illumination light beam, the homogenizing element being located between the beam splitting element and the quarter-wave plate, and configured to homogenize the illumination light beam incident on the homogenizing element.

[0010] In a preferred embodiment, the homogenizing element is a fly-eye lens.

[0011] In a preferred embodiment, the system further comprises: a homogenizing element disposed on the transmission path of the illumination light beam and located between the quarter-wave plate and the reflective element, wherein the homogenizing element is used to homogenize the illumination light beam incident on the homogenizing element.

[0012] In a preferred embodiment, the homogenizing element is a light guide rod or a fly-eye lens.

[0013] In a preferred embodiment, the light guide rod is hollow or solid.

[0014] In a preferred embodiment, the surface of the reflective element has a diffusion layer.

[0015] In a preferred embodiment, a diffuser is further included, located between the quarter-wave plate and the homogenizing element.

[0016] In a preferred embodiment, the illumination light beam includes two or more of red light, blue light and green light.

[0017] In a preferred embodiment, the system further includes: a diopter element, a light valve, and a projection lens, wherein the illumination beam passes through the diopter element and then enters the light valve, which converts the illumination beam into the image beam. The projection lens is disposed on the optical path of the image beam.

[0018] In a preferred embodiment, the diopter element is a lens with positive refractive power or a curved mirror.

[0019] In a preferred embodiment, when the illumination beam is incident on the homogenizing element from the beam splitting element, the illumination beam is imaged on the reflecting element; when the illumination beam is incident on the homogenizing element from the reflecting element, the illumination beam is imaged on the light valve.

[0020] In a preferred embodiment, a total reflection lens is further included. The total reflection lens is located on the optical path of the illumination light beam and between the refractive element and the light valve.

[0021] Based on the above, the projection device provided by the present invention can simultaneously generate illumination beams with multiple colors. A beam splitter is used to transform the illumination beam into a single polarization beam. A reflector and a homogenizer are used to change the optical path and shape the illumination beam. A light valve converts the illumination beam into a colored image beam to project the desired image. This configuration simplifies the optical path and reduces system size. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A is a schematic diagram of a light source device according to an embodiment of the present invention.

[0023] Figure 1Bis a schematic diagram of a light source device according to an embodiment of the present invention.

[0024] Figure 2 is a schematic diagram of a light source device according to an embodiment of the present invention.

[0025] Figure 3A 、 Figure 3B is a schematic diagram of a light source device according to an embodiment of the present invention.

[0026] Figure 4 is a schematic diagram of a projection device according to an embodiment of the present invention.

[0027] Figure 5A 、 Figure 5B is a schematic diagram of a projection device according to an embodiment of the present invention.

[0028] Figure 6 is a schematic diagram of a projection device according to an embodiment of the present invention.

[0029] Figure 7 is a schematic diagram of a projection device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the present invention is described in detail below with reference to the embodiments.

[0031] Figure 1A is a schematic diagram of a light source device according to an embodiment of the present invention. Figure 1A The present invention provides a projection device, including a light source device 100A. The light source device 100A includes a light source 110 , a beam splitter 120 , a quarter-wave plate 130 , and a reflective element 150 .

[0032] The light source 110 is used to emit an illumination beam L, and the illumination beam L has at least two different colors. Figure 1A As shown, the light source 110 includes a first light source 110A for emitting a first color light LA; a second light source 110B for emitting a second color light LB different from the first color light LA; and a third light source 110C for emitting a third color light LC different from the first color light LA and the second color light LB. The first color light LA, the second color light LB, and the third color light LC combine to form an illumination light beam L. For simplicity, the following description refers to the light source 110 as including the first light source 110A, the second light source 110B, and the third light source 110C. The illumination light beam L includes the first color light LA, the second color light LB, and the third color light LC.

[0033] In this embodiment, the light source 110 includes three light sources capable of emitting light of different colors. In some embodiments, the first light source 110A, the second light source 110B, and the third light source 110C may be laser light sources, with the first color light LA being red, the second color light LB being green, and the third color light LC being blue. For example, the first light source 110A may include a plurality of red laser diodes arranged in an array, the second light source 110B may include a plurality of green laser diodes arranged in an array, and the third light source 110C may include a plurality of blue laser diodes arranged in an array, but the present disclosure is not limited thereto. In some embodiments, the light source 110 may include light sources emitting two or more different colors of light, for example, two, or more than three, depending on actual needs, and the present disclosure is not limited thereto. In some embodiments, the illumination beam L includes two or more of the following: red, blue, and green.

[0034] In some embodiments, the first light source 110A, the second light source 110B, and the third light source 110C of the light source 110 can emit light beams with specific polarization directions, namely, light beams with a first linear polarization direction, such as light beams with an S polarization direction or light beams with a P polarization direction. In this embodiment, the first color light LA, the second color light LB, and the third color light LC emitted by the first light source 110A, the second light source 110B, and the third light source 110C of the light source 110 all have the same polarization direction. For example, the first color light LA, the second color light LB, and the third color light LC can be emitted with an S polarization direction, thereby forming an illumination light beam L with an S polarization direction.

[0035] like Figure 1A As shown, the beam splitter 120, the quarter-wave plate 130, and the reflective element 150 are located on the transmission path of the illumination light beam L. After passing through the beam splitter 120, the illumination light beam L sequentially enters the quarter-wave plate 130 and the reflective element 150. After being reflected by the reflective element 150, the illumination light beam L sequentially passes through the quarter-wave plate 130 and the beam splitter 120. When the illumination light beam L passes through the beam splitter 120 and the quarter-wave plate 130, the illumination light beam L has a second linear polarization direction, and the first linear polarization direction is perpendicular to the second linear polarization direction.

[0036] Specifically, the illumination beam L emitted by the light source 110 enters the beam splitter 120. In this embodiment, the beam splitter 120 is configured to reflect incident light having a first linear polarization direction and to allow incident light having a second linear polarization direction to pass through. In this embodiment, the first linear polarization direction is S polarization, and the second linear polarization direction is P polarization. Therefore, in this embodiment, the beam splitter 120 is configured to reflect incident light having S polarization and to allow incident light having P polarization to pass through. In this embodiment, the incident light is the illumination beam L.

[0037] Therefore, in this embodiment, the S-polarized illumination beam L emitted by the light source 110 enters the beam splitter 120 and is reflected by the beam splitter 120. In another embodiment, if the excitation beam emitted by the light source 110 has both S-polarization and P-polarization, the P-polarized illumination beam L will pass through the beam splitter 120 and exit the system consisting of the light source 110, the beam splitter 120, the quarter-wave plate 130, and the reflective element 150.

[0038] In other embodiments, the first linear polarization direction may be P polarization, and the second linear polarization direction may be S polarization. That is, the beam splitter 120 is configured to reflect incident light with P polarization and pass incident light with S polarization.

[0039] The illumination light beam L reflected by the beam splitter 120 is incident on the quarter-wave plate 130 and the reflective element 150 in sequence. Therefore, the light source 110 and the reflective element 150 are located on the same side of the beam splitter 120 .

[0040] The illumination light beam L reflected by the beam splitter 120 enters the quarter-wave plate 130 located on the optical path, so that the polarization direction of the illumination light beam L changes from the first linear polarization direction to circular polarization, and then enters the reflection element 150 .

[0041] In some embodiments, the reflective element 150 is configured to reflect the illumination light beam L, such that the illumination light beam L sequentially passes through the quarter-wave plate 130 and the beam splitter 120. In some embodiments, the reflective element 150 is a specular reflective element, which may be reflective glass, configured to simultaneously reflect red light, green light, and blue light. In other embodiments, the reflective element 150 may be made of a metal coating, such as silver, aluminum, or a dielectric coating. In some embodiments, the surface of the reflective element 150 further comprises a diffusion layer, such as a microstructure, scattering particles, or a similar layer, although the present disclosure is not limited thereto.

[0042] The illumination light beam L emitted by the reflective element 150 is incident on the quarter-wave plate 130 along the optical path. At this time, the polarization direction of the illumination light beam L changes from circular polarization to linear polarization again. However, this time the linear polarization direction changes from S polarization of the illumination light beam L emitted by the light source 110 to P polarization, i.e., the second linear polarization direction. The first linear polarization direction is perpendicular to the second linear polarization direction.

[0043] The illumination beam L passing through the quarter-wave plate 130 enters the spectrometer 120 along the optical path. Since the illumination beam L is P-polarized and the spectrometer 120 allows the incident beam with P polarization to pass through, the illumination beam L passes through the spectrometer 120 and proceeds along the optical path.

[0044] Therefore, with the light source device 100A shown in FIG. 1 , the light source 110 capable of emitting two or more colors of light can be used to emit the illumination beam L. The beam splitter 120 can be used to make the illumination beam L have the same polarization direction and to change the optical path of the illumination beam L.

[0045] Figure 1B is a schematic diagram of a light source device according to another embodiment of the present invention. Figure 1B The light source device 100B shown is Figure 1A The light source device 100A shown is similar, so the similarities are not repeated here. Figure 1B The light source device 100B shown is Figure 1A The difference in the illustrated light source device 100A is that the illumination beam L emitted by the light source 110 is polarized P. Therefore, when the illumination beam L enters the beam splitter 120, it passes through the beam splitter 120, sequentially passing through the quarter-wave plate 130 and the reflective element 150, and then returns to the beam splitter 120 along its original optical path. After passing through the beam splitter 120 twice, the P-polarized illumination beam L becomes S-polarized. Therefore, it is reflected by the beam splitter 120 and continues along its original optical path.

[0046] In this embodiment, the light source 110 is located on one side of the beam splitter element 120 , while the quarter-wave plate 130 and the reflective element 150 are both located on the other opposite side of the beam splitter element 120 .

[0047] Therefore, according to the linear polarization direction of the light required by the system, whether it is S polarization or P polarization, an appropriate light source device can be selected, such as Figure 1A Light source device 100A or Figure 1B As shown in the light source device 100B.

[0048] Figure 2 is a schematic diagram of a light source device according to an embodiment of the present invention. Figure 2 The light source device 100C shown is Figure 1A The light source device 100A shown is similar, so the similarities are not repeated here. Figure 2 The light source device 100C shown is Figure 1AThe difference between the light source device 100A shown is that the light source device 100C further includes a homogenizing element 160A, which is disposed on the transmission path of the illumination light beam L and is located between the beam splitter 120 and the reflective element 150. In some embodiments, the homogenizing element 160A is located between the beam splitter 120 and the quarter-wave plate 130. In other embodiments, the homogenizing element 160A may also be located between the quarter-wave plate 130 and the reflective element 150, but the present disclosure is not limited thereto. The homogenizing element 160A is used to homogenize the illumination light beam L incident on the homogenizing element 160A. Therefore, when the illumination light beam L is emitted by the light source 110 and sequentially enters the homogenizing element 160A, the quarter-wave plate 130, and the reflective element 150, the reflective element 150 is located at the end opposite to the light entrance side of the homogenizing element 160A, that is, the light exit side of the homogenizing element 160A.

[0049] Specifically, when the illumination beam L enters the homogenizing element 160A, the homogenizing element 160A can shape the illumination beam L. For example, the illumination beam L having a circular spot emitted by the light source 110 can be transformed into a rectangular spot. The shaped illumination beam L is then incident on the quarter-wave plate 130 and imaged onto the reflective element 150. Furthermore, when the illumination beam L is reflected by the reflective element 150 and then passes through the homogenizing element 160A, the homogenizing element 160A can perform a second shaping on the illumination beam L reflected by the reflective element 150, so that the illumination beam L has a desired shape.

[0050] Therefore, in this embodiment, the illumination light beam L including the first color light LA, the second color light LB and the third color light LC passes through the homogenizing element 160A twice, that is, is shaped twice.

[0051] In some embodiments, the homogenizing element 160A is a fly eye lens, or has other similar functions, but the present disclosure is not limited thereto.

[0052] In some embodiments, the homogenizing element 160A may also be configured to Figure 1B A similar position of the light source device 100B.

[0053] Figure 3A 、 Figure 3B is a schematic diagram of a light source device according to an embodiment of the present invention. Figure 3A and Figure 3B The same light source device 100D is shown, wherein Figure 3A is the optical path of the illumination light beam L emitted by the light source 110 and incident on the reflective element 150, and Figure 3B It is the optical path of the illumination light beam L after being reflected by the reflective element 150 , so that the optical path of the illumination light beam is clearly discernible.

[0054] Figure 3A 、 Figure 3B The light source device 100D shown is Figure 1A The light source device 100A shown is similar, so the similarities are not repeated here. Figure 3A 、 Figure 3B The light source device 100D shown is Figure 1A The light source device 100A shown differs in that the light source device 100C further includes a homogenizing element 160B, which is disposed in the transmission path of the illumination light beam L, between the quarter-wave plate 130 and the reflective element 150. The homogenizing element 160B is used to homogenize the illumination light beam L incident on the homogenizing element 160B. Therefore, when the illumination light beam L is emitted by the light source 110 and sequentially enters the homogenizing element 160B and the reflective element 150, the reflective element 150 is located at the end opposite the light-entry side of the homogenizing element 160B, i.e., the light-exit side of the homogenizing element 160B.

[0055] Specifically, when the illumination beam L enters the homogenizing element 160B, the homogenizing element 160B can shape the illumination beam L. For example, the illumination beam L having a circular spot emitted by the light source 110 can be transformed into a rectangular spot. The shaped illumination beam L is then incident on the quarter-wave plate 130 and imaged onto the reflective element 150. Furthermore, when the illumination beam L is reflected by the reflective element 150 and then passes through the homogenizing element 160B, the homogenizing element 160B can perform a second shaping on the illumination beam L reflected by the reflective element 150, so that the illumination beam L has a desired shape.

[0056] Therefore, in this embodiment, the illumination light beam L including the first color light LA, the second color light LB and the third color light LC passes through the homogenizing element 160B twice, that is, is shaped twice.

[0057] In some embodiments, the homogenizing element 160B is a light guide rod, or has other similar functions, but the present disclosure is not limited thereto. In some embodiments, the homogenizing element 160B, ie, the light guide rod, is hollow or solid.

[0058] In some embodiments, the area of the opening 160B1 of the light guide on the reflective element 150 side is A1, and the area of the opening 160B2 on the reflective element 150 side is A2, so A1≧A2. Therefore, when the illumination beam L enters the homogenizing element 160B, it is not only shaped but also converged.

[0059] In some embodiments, the reflective element 150 may be located in the opening 160B2 of the homogenizing element 160B and combined with the homogenizing element 160B to reduce light loss generated when the illumination beam L passes through the homogenizing element 160B and enters the reflective element 150 , thereby improving the reflection efficiency of the illumination beam L on the reflective element 150 .

[0060] In some embodiments, the homogenizing element 160B may also be configured to Figure 1B A similar position of the light source device 100B.

[0061] like Figure 3A 、 Figure 3B As shown, the light source device 100D further includes a lens 170 located between the quarter-wave plate 130 and the homogenizing element 160B. The lens 170 generally refers to a lens with a light-converging function, which is used to change the characteristics of the illumination light beam L.

[0062] like Figure 3A 、 Figure 3B As shown, the light source device 100D further includes a diffuser 172 located between the quarter-wave plate 130 and the homogenizing element 160B. The diffuser 172 is used to change the shape of the illumination beam L. In some embodiments, the surface of the diffuser 172 includes microstructures or diffusion particles, or other materials having similar functions.

[0063] Figure 4 is a schematic diagram of a projection device according to an embodiment of the present invention. Figure 4 . Figure 4 The projection device 10A includes a light source device 100C for generating an illumination beam L. The light source device 100C may also be Figure 1A The light source device 100A shown, Figure 1B The light source device 100B shown, Figure 3A 、 Figure 3B The present disclosure is not limited to any of the light source devices 100D shown.

[0064] In this embodiment, the light source device 100C further includes a lens 170 located between the homogenizing element 160A and the quarter-wave plate 130 for changing the optical properties of the illumination light beam L.

[0065] like Figure 4 As shown, projection device 10A further includes a diopter 210, a light valve 220, and a projection lens 230. An illumination beam L emitted by light source device 100C passes through diopter 210 and enters light valve 220. Light valve 220 converts illumination beam L into an image beam LI. Projection lens 230 is positioned on the optical path of image beam LI.

[0066] Specifically, the diopter element 210 generally refers to a lens with a light-converging function, so as to project the illumination light beam L onto the light valve 220. Specifically, in some embodiments, the diopter element 210 is a lens with positive refractive power.

[0067] In this embodiment, the illumination beam L emitted by the light source device 100C first enters the diopter 240 before entering the diopter element 210. The diopter 240 is located in the optical path of the illumination beam L. The diopter 240 is located between the beam splitter 120 and the diopter element 210 and is used to change the optical path of the illumination beam L. In some embodiments, the diopter 240 can be a plane reflector, a curved reflector, or other mirrors having similar functions, but the present disclosure is not limited thereto.

[0068] The illumination beam L is reflected by the diopter 240, passes through the diopter element 210, and then enters the light valve 220. The light valve 220 is adapted to convert the illumination beam L into an image beam LI. Specifically, the light valve 220 converts the first color light LA, the second color light LB, and the third color light LC in the illumination beam L into a first image beam LIA, a second image beam LIB, and a third image beam LIC, respectively. The first image beam LIA, the second image beam LIB, and the third image beam LIC form the image beam LI. In this embodiment, the light valve 220 is, for example, a digital micro-mirror device (DMD) or a liquid-crystal-on-silicon (LCOS) panel. However, in other embodiments, the light valve 220 may alternatively be a transmissive liquid crystal panel or other beam modulator.

[0069] In addition, when the illumination beam L enters the homogenizing element 160A from the reflective element 150 , the illumination beam L forms an image on the light valve 220 .

[0070] Projection lens 230 is located in the transmission path of image beam LI and is suitable for projecting image beam LI onto a screen (not shown) to form an image. In this embodiment, projection lens 230 includes a combination of one or more optical lenses with refractive power. The optical lenses include, for example, various combinations of non-planar lenses such as biconcave lenses, biconvex lenses, concave-convex lenses, convex-concave lenses, plano-convex lenses, and plano-concave lenses. The present invention does not limit the type and form of projection lens 230.

[0071] After the illumination beam L converges on the light valve 220, the light valve 220 sequentially converts the different colored lights in the illumination beam L into corresponding image beams LI and transmits them to the projection lens 230. Therefore, the image screen projected by the image beams LI converted by the light valve 220 can be a color screen.

[0072] Figure 5A 、 Figure 5B is a schematic diagram of a projection device according to an embodiment of the present invention. Figure 5A and Figure 5B The same projection device 10B is shown, wherein Figure 5A is the optical path of the illumination light beam L emitted by the light source 110 and incident on the reflective element 150, and Figure 5B It is the optical path of the illumination light beam L after being reflected by the reflective element 150 , so that the optical path of the illumination light beam is clearly discernible.

[0073] Figure 5A 、 Figure 5B The projection device 10B shown is Figure 4 The projection device 10A shown is similar, so the similarities are not repeated here. Figure 5A 、 Figure 5B The projection device 10B shown is Figure 4 The difference of the projection device 10A shown is that Figure 5A 、 Figure 5B In the figure, the light source device is light source device 100D. Projection device 10B also includes an optical actuator 212. Illumination beam L is reflected by folding mirror 240, passes through optical actuator 212, and then enters light valve 220. Image beam LI passes through the repeatedly vibrating mirror on optical actuator 212, increasing image resolution.

[0074] In addition, when the illumination beam L enters the homogenizing element 160B from the reflective element 150 , the illumination beam L forms an image on the light valve 220 .

[0075] Figure 6 is a schematic diagram of a projection device according to an embodiment of the present invention. Figure 6 The projection device 10C shown is Figure 4 The projection device 10A shown is similar, so the similarities are not repeated here. Figure 6 The projection device 10C shown is Figure 4 The difference of the projection device 10A shown is that Figure 6 In the embodiment, the refractive element 210 is a curved mirror with positive refractive power. After the illumination beam L is reflected by the refractive element 210, it enters the light valve 220. The light valve 220 converts the illumination beam L into an image beam LI, which then enters the projection lens 230.

[0076] Therefore, the optical path of the illumination light beam L can be changed by using the diopter element 210 .

[0077] Figure 7 is a schematic diagram of a projection device according to an embodiment of the present invention. Figure 7 The projection device 10D shown is Figure 4 The projection device 10A shown is similar, so the similarities are not repeated here. Figure 7 The projection device 10D shown is Figure 4The difference between the projection device 10A and the projection device 10D is that the projection device 10D further includes a totally internally reflective lens (TIR) 222. The TIR lens 222 is located in the optical path of the illumination light beam L, between the diopter 210 and the light valve 220. After passing through the diopter 210, the illumination light beam L enters the TIR lens 222.

[0078] Total reflection lens 222 is a right-angled triangular prism. Illumination beam L enters total reflection lens 222 and is totally reflected by the long side of total reflection lens 222 before entering light valve 220. Light valve 220 converts illumination beam L into image beam LI, which then passes through total reflection lens 222 and lens 224 before entering projection lens 230.

[0079] Therefore, the combination of the total reflection lens 222 and the lens 224 can achieve the effect of changing the optical paths of the illumination light beam L and the image light beam LI.

[0080] In summary, the projection device provided by the present invention can simultaneously generate illumination beams with multiple colors. A beam splitter is used to transform the illumination beam into a single polarization beam. A reflector and a homogenizer are used to change the optical path and shape the illumination beam. A light valve converts the illumination beam into a colored image beam to project the desired image. This configuration simplifies the optical path and reduces system size.

[0081] The present invention has been described with reference to the above embodiments. However, the above embodiments are merely exemplary embodiments of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and improvements that do not depart from the spirit and scope of the present invention are intended to be protected by the present invention.

Claims

1. A projection device, characterized in that: include: A light source device, wherein the light source device comprises: a light source, a beam splitter, a quarter wave plate, and a reflective element, wherein: The light source is used to emit an illumination beam having at least two different colors of light and a first linear polarization direction. The beam splitter, the quarter-wave plate, and the reflective element are located on a transmission path of the illumination beam. After passing through the beam splitter, the illumination light beam sequentially enters the quarter-wave plate and the reflective element, and after being reflected by the reflective element, sequentially passes through the quarter-wave plate and the beam splitter. After passing through the beam splitter and the quarter-wave plate, the illumination light beam has a second linear polarization direction, and the first linear polarization direction is perpendicular to the second linear polarization direction.

2. The projection device according to claim 1, wherein The beam splitter element is used for reflecting the illumination light beam with the first linear polarization direction and for allowing the illumination light beam with the second linear polarization direction to pass through; the light source and the reflective element are located on the same side of the beam splitter element.

3. The projection device according to claim 1, wherein: The beam splitter element is used for passing the illumination light beam with a first linear polarization direction and for reflecting the illumination light beam with a second linear polarization direction. The light source and the reflective element are respectively located on two sides of the beam splitter element.

4. The projection device according to claim 1, wherein: Also includes: A homogenizing element is disposed on the transmission path of the illumination light beam. The homogenizing element is located between the beam splitting element and the quarter-wave plate. The homogenizing element is used to homogenize the illumination light beam incident on the homogenizing element.

5. The projection device according to claim 4, wherein: The homogenizing element is a fly-eye lens.

6. The projection device according to claim 1, wherein: Also includes: The homogenizing element is disposed on the transmission path of the illumination light beam and located between the quarter-wave plate and the reflective element. The homogenizing element is used for homogenizing the illumination light beam incident on the homogenizing element.

7. The projection device according to claim 6, wherein: The homogenizing element is a light guide column or a fly-eye lens.

8. The projection device according to claim 7, wherein: The light guide column is hollow or solid.

9. The projection device according to claim 6, wherein: The surface of the reflective element has a diffusion layer.

10. The projection device according to claim 4 or 6, characterized in that: A diffuser is also included, located between the quarter-wave plate and the homogenizing element.

11. The projection device according to claim 6, wherein: The illumination light beam includes two or more of red light, blue light and green light.

12. The projection device according to claim 1, wherein: Also includes: A refractive element, a light valve and a projection lens, wherein the illumination beam passes through the refractive element and then enters the light valve, the light valve converts the illumination beam into the image beam, and the projection lens is arranged on the optical path of the image beam.

13. The projection device according to claim 12, wherein: The refractive element is a lens with positive refractive power or a curved mirror.

14. The projection device according to claim 12, wherein: When the illumination beam enters the homogenizing element from the beam splitting element, the illumination beam forms an image on the reflecting element; when the illumination beam enters the homogenizing element from the reflecting element, the illumination beam forms an image on the light valve.

15. The projection device according to claim 12, wherein: The invention also includes a total reflection lens, which is located on the optical path of the illumination light beam and between the refractive element and the light valve.

Images