Optical system and projection device

Abstract

The utility model provides an optical system and a projection device. The optical system comprises a light source, a polarization beam splitter and a first LCD assembly. The light source emits light; the polarization beam splitter is used for splitting the light into first polarized light and second polarized light; the first LCD assembly is used for modulating the first polarized light to form first modulated light, and the first LCD assembly comprises a first substrate, a first liquid crystal layer, a second substrate and a first polaroid which are sequentially stacked in the light path direction. The utility model aims to improve the heat dissipation problem of the optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of projection device, in particular to an optical system and a projection device. BACKGROUND

[0002] The projector, also known as a projector, is a device that can project images or videos onto a screen. The optical system of the projector usually includes a light source and an LCD component, the light source is used for emitting light, and the LCD component is used for modulating light. The current mainstream LCD component mainly includes a front polarizing plate, an array substrate, a liquid crystal layer, a color film substrate and a rear polarizing plate. Among them, the polarizing plate allows polarized light of a specific direction to pass through, while blocking polarized light of other directions. The liquid crystal molecules in the liquid crystal layer can change the polarization direction of the light under the condition of power-on or power-off, thereby affecting whether the light can pass through the rear polarizing plate. Since the lost polarized light is mainly absorbed by the polarizing plate and converted into heat, it greatly increases the difficulty of heat dissipation design of the projector. CONTENT OF THE UTILITY MODEL

[0003] The utility model provides a kind of optical system and projection device, to improve the heat dissipation problem of optical system.

[0004] To achieve the above object, the present application provides an optical system, comprising:

[0005] A light source for emitting light;

[0006] A polarization splitting device for splitting the light into first polarized light and second polarized light; and

[0007] A first LCD component for modulating the first polarized light to form first modulated light, wherein the first LCD component includes a first substrate, a first liquid crystal layer, a second substrate and a first polarizing plate stacked in sequence along the optical path.

[0008] Optionally, in an embodiment, the optical system further comprises:

[0009] A second LCD component for modulating the second polarized light to form second modulated light; and

[0010] A polarization combining device having an input side facing the first LCD component and an output side facing the second LCD component, the polarization combining device is used to output after combining the first modulated light and the second modulated light.

[0011] Optionally, in an embodiment, the polarization splitting device is a S-polarized light transmitting and P-polarized light reflecting splitting plate, and the polarization combining device is a S-polarized light transmitting and P-polarized light reflecting combining plate; or

[0012] The polarization splitting device is a P-passing and S-reflection splitting film, and the polarization combining device is a P-passing and S-reflection combining film.

[0013] Optionally, in an embodiment, the second LCD assembly comprises a second polarizing film, a third substrate, a second liquid crystal layer, a reflecting layer and a fourth substrate which are sequentially stacked, and the second polarizing film is arranged close to the polarization combining device, wherein the reflecting layer is configured to reflect the second modulated light to the light exit side of the polarization combining device.

[0014] Optionally, in an embodiment, the optical system further comprises a first reflecting mirror arranged between the polarization splitting device and the first LCD assembly, configured to reflect the first polarized light to the first LCD assembly; and / or,

[0015] The optical system further comprises a second reflecting mirror arranged between the polarization splitting device and the polarization combining device, and configured to reflect the second polarized light to the light entrance side of the polarization combining device, so that the second polarized light is incident on the second LCD assembly after passing through the polarization combining device.

[0016] Optionally, in an embodiment, the optical system further comprises a first Fresnel mirror arranged between the polarization combining device and the second LCD assembly, and a Fresnel surface of the first Fresnel mirror is arranged towards the second LCD assembly.

[0017] Optionally, in an embodiment, the second LCD assembly comprises a fifth substrate, a third liquid crystal layer, a sixth substrate and a third polarizing film which are sequentially stacked, and the third polarizing film is arranged close to the polarization combining device.

[0018] Optionally, in an embodiment, the optical system further comprises a third reflecting mirror arranged between the polarization splitting device and the first LCD assembly, configured to reflect the first polarized light to the first LCD assembly; and / or,

[0019] The optical system further comprises a fourth reflecting mirror arranged between the polarization splitting device and the second LCD assembly, and located on the light exit side of the polarization combining device, configured to reflect the second polarized light to the second LCD assembly; and / or,

[0020] The optical system further comprises a second Fresnel mirror arranged between the second LCD assembly and the polarization splitting device, and a third Fresnel mirror arranged between the second LCD assembly and the polarization combining device.

[0021] Optionally, in an embodiment, the optical system further comprises:

[0022] a fourth Fresnel mirror arranged between the first LCD assembly and the polarization splitting device; and

[0023] a fifth Fresnel mirror arranged between the first LCD assembly and the polarization combining device.

[0024] The present application also provides a projection device, which comprises the optical system described above and a projection lens for receiving the light output by the optical system.

[0025] In the optical system provided by the present application, the polarization splitting device is arranged between the light source and the first LCD assembly to divide the light beam into two polarized lights of different polarization states, so that one polarizing plate in the LCD assembly can be replaced. On the one hand, the problem of high heat generation and difficult heat dissipation caused by the heat generation of the polarizing plate can be avoided. On the other hand, the yellowing phenomenon of the polarizing plate at high temperature can also be avoided, and the light output effect is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the drawings shown.

[0027] Figure 1 Structure schematic diagram of the projection device provided by the first embodiment of the present application;

[0028] Figure 2 Structure schematic diagram of the projection device provided by the second embodiment of the present application;

[0029] Figure 3 Structure schematic diagram of the projection device provided by the third embodiment of the present application;

[0030] Figure 4 Structure schematic diagram of the projection device provided by the fourth embodiment of the present application;

[0031] Figure 5 Structure schematic diagram of the projection device provided by the fifth embodiment of the present application;

[0032] Figure 6 Structure schematic diagram of an embodiment of the second LCD assembly;

[0033] Figure 7 Structure schematic diagram of another embodiment of the second LCD assembly;

[0034] Figure 8 Fig. 1 is a schematic diagram of working principle of a light splitting sheet allowing P light to pass and reflecting S light;

[0035] Figure 9 Fig. 2 is a schematic diagram of working principle of a light splitting sheet allowing S light to pass and reflecting P light.

[0036] Brief Description of the Drawings

[0037]

[0038]

[0039] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] In the related art, an LCD assembly mainly includes a front polarizing sheet, an array substrate, a liquid crystal layer, a color film substrate and a rear polarizing sheet. The polarizing sheet allows polarized light in a specific direction to pass through and blocks polarized light in other directions. The liquid crystal molecules in the liquid crystal layer can change the polarization direction of light under the condition of power-on or power-off, thereby affecting whether the light can pass through the rear polarizing sheet.

[0042] In some applications, the polarizing sheet only allows part of light to pass through, which reduces the light transmittance and easily affects the on-screen brightness during projection. Moreover, since the lost polarized light is mainly absorbed by the polarizing sheet and converted into heat, the polarizing sheet is prone to yellowing due to high temperature, which not only affects the on-screen effect, but also causes the projection device to have high heat generation and large heat dissipation difficulty, greatly increasing the design difficulty of heat generation and heat dissipation of the projector.

[0043] In view of this, the embodiments of the present application provide an optical system 100 which can be applied in a projection device 1000, an illumination device or other display equipment. The optical system 100 includes a light source 1, a polarization splitting device 2 and a first LCD assembly, which can improve the heat dissipation problem of the optical system 100. Hereinafter, the optical system 100 applied in the projection device 1000 will be taken as an example, and the structure and effects thereof will be described in detail with reference to the accompanying drawings.

[0044] Please refer to Figure 1The projection device 1000 includes an optical system 100 and a projection lens 200. The optical system 100 is configured to provide modulated light and input the modulated light into the projection lens 200. The projection lens 200 is the last link of the entire optical path and determines the core parameters of the projection device 1000, such as picture color, brightness, focusing definition, and the like, that is, the device for projecting a picture onto a screen.

[0045] It should be noted that the projection lens 200 can also be a component of the optical system 100. Here, the projection lens 200 is distinguished from the optical system 100 for ease of description, and should not be construed as a limitation on the projection lens 200 and the optical system 100.

[0046] Further, as shown in Figure 1 The optical system 100 provided by the embodiments of the present application includes a light source 1, a polarization splitting device 2, and a first LCD assembly. The light source 1 is configured to emit light. The polarization splitting device 2 is configured to split the light into first polarized light and second polarized light. The first LCD assembly is configured to modulate the first polarized light to form first modulated light. The first LCD assembly includes, in sequence along an optical path, a first substrate 31, a first liquid crystal layer 32, a second substrate 33, and a first polarizer 34.

[0047] In the optical system 100 provided by the present application, the polarization splitting device 2 is arranged between the light source 1 and the first LCD assembly to split the light beam into two polarized lights of different polarization states, thereby replacing the front polarizer in the LCD assembly of the conventional design. On the one hand, this can avoid the problem of high heat generation and difficulty in heat dissipation caused by heating of the polarizer. On the other hand, this can also avoid the yellowing phenomenon of the polarizer at high temperature, thereby improving the light output effect. When the optical system 100 is applied to the projection device 1000, the problem of high heat generation and difficulty in heat dissipation of the projection device 1000 can be improved, and the on-screen effect of the projection device 1000 can be improved. It should be understood that the on-screen effect refers to the display effect of the projected image on the screen, the screen, or other projection surfaces.

[0048] The light source 1 can emit illumination light to provide illumination light for the optical system 100. The illumination light can include single-band light or multiple-band light, such as mixed light composed of red, green, and blue light. The light source 1 can be a single light source 1 or a group of light sources 1 composed of multiple light sources 1. The light source 1 can be a laser light source 1, an LED light source 1, or a fluorescent light source 1, and the like.

[0049] In some embodiments, the light source 1 can further include a light cone, a lens, or other light beam processing elements. The light cone is generally in the shape of a truncated cone, such as a four-sided truncated cone with a small-diameter end as an input light side, which can collect light and play a role in reducing the angle of light (collimation) and spot shaping.

[0050] Please refer to Figure 8 and Figure 9 The polarization splitting device 2 is used for splitting the received light into two polarized lights of different polarization states: first polarized light and second polarized light. In some embodiments, the beams of the first and second polarized light are perpendicular to each other, and the first and second polarized light can be P light (Parallel Light) and S light (Perpendicular Light), respectively. The polarization splitting device 2 can be designed to allow the first polarized light to pass through but reflect the second polarized light, or to allow the second polarized light to pass through but reflect the first polarized light. The polarization splitting device 2 can adopt any device with a splitting function commonly used in the art, such as a polarization beam splitter (PBS), a liquid crystal device, a holographic grating polarization splitting device (APF), and the like. The polarization splitting device 2 has good temperature resistance and is not prone to yellowing. Compared with the spacing between the front polarizing plate and the substrate in the design of a conventional LCD assembly, the spacing between the polarization splitting device 2 and the substrate of the LCD assembly is relatively farther, so that heat is not easily accumulated. In a specific embodiment, the polarization splitting device 2 is selected from a PBS. Further, the polarization splitting device 2 can be a S light transmission and P light reflection splitting plate or a P light transmission and S light reflection splitting plate. When light enters the S light transmission and P light reflection splitting plate, S light can pass through the polarization splitting device 2, and P light is reflected by the light entrance side of the polarization splitting device 2. When light enters the P light transmission and S light reflection splitting plate, P light can pass through the polarization splitting device 2, and S light is reflected by the light entrance side of the polarization splitting device 2. It can be understood that, herein, the light entrance side and the light exit side are two opposite sides of an optical element, which are defined with respect to the propagation direction of light. For example, the polarization splitting device 2 has a first side and a second side arranged oppositely, light enters the device from the first side and exits from the second side, so that the first side is the light entrance side and the second side is the light exit side.

[0051] In some embodiments, the polarization splitting device 2 is arranged at an angle with respect to the light beam, and the angle can be 15°-75°, which can satisfy the transmission of the first polarized light and the reflection of the second polarized light. Further, the angle can be 45°.

[0052] The arrangement of the polarization splitting device 2 can replace the polarizing plate in the LCD assembly for converting the light beam into polarized light to obtain the first polarized light. While reducing heat generation and improving yellowing problems, it is ensured that the first LCD assembly only needs to modulate the first polarized light, thereby reducing the workload of the first LCD assembly and helping to improve the modulation efficiency.

[0053] The first LCD component can be a transmissive LCD, which includes a first substrate 31, a first liquid crystal layer 32, a second substrate 33 and a first polarizer 34 stacked in sequence along an optical path direction. The optical path direction refers to the propagation direction of the light beam. In this embodiment, the light emitted by the light source 1 enters the polarization beam splitter 2 and is divided into first polarized light and second polarized light. The first polarized light is guided to enter the first LCD component and sequentially passes through the first substrate 31, the first liquid crystal layer 32, the second substrate 33 and the first polarizer 34 to complete light modulation and form first modulated light. The first substrate 31 can be an array substrate (TFT), and the second substrate 33 can be a color filter substrate (CF).

[0054] In some embodiments, the first LCD component has only one polarizer, i.e., the first polarizer 34, which replaces the front polarizer in the traditional LCD, simplifies the number of components and improves heat dissipation.

[0055] In some embodiments, the distance between the first LCD component and the polarization beam splitter 2 can be greater than or equal to 8 mm, which can avoid heat accumulation and improve heat dissipation.

[0056] In order to further improve the light brightness and improve the screen brightness and effect of the projection device 1000, another embodiment of the optical system 100 is provided. In this embodiment, the optical system 100 further includes a second LCD component and a polarization beam combiner 5. The second LCD component is used to modulate the second polarized light to form second modulated light. The polarization beam combiner 5 is used to combine the two modulated lights, which can be any device with beam splitting / combining function in the art, such as PBS, liquid crystal device, APF, etc. The polarization beam combiner 5 has an entrance side and an exit side. The entrance side is arranged towards the first LCD component, and the exit side is arranged towards the second LCD component. In this way, the first modulated light and the second modulated light can be combined and output, which plays a role in light combination. In this embodiment, the light source 1 is split and then incident on different LCD components for light combination, which can avoid half of the polarized light loss. At the same time, since the two polarized lights are modulated by different LCD components, it is helpful to improve the modulation efficiency.

[0057] In some embodiments, the distance between the second LCD component and the polarization beam splitter 2 can be greater than or equal to 8 mm, which can avoid heat accumulation and improve heat dissipation.

[0058] The polarization combining device 5 can be a transmissive S-polarized light and reflective P-polarized light combining sheet or a transmissive P-polarized light and reflective S-polarized light combining sheet. When the light enters the transmissive S-polarized light and reflective P-polarized light combining sheet, the S-polarized light can pass through and the P-polarized light is reflected. When the light enters the transmissive P-polarized light and reflective S-polarized light combining sheet, the P-polarized light can pass through and the S-polarized light is reflected. If the polarization combining device 5 allows the first modulated light to pass through and reflects the second modulated light, the first modulated light is guided to enter from the light-in side of the polarization combining device 5, the second modulated light is guided to enter from the light-out side of the polarization combining device 5, and the second modulated light can be reflected on the light-out side and combined with the first modulated light passing through the polarization combining device 5.

[0059] As shown in FIG. 1, in an embodiment, the polarization splitting device 2 is a transmissive S-polarized light and reflective P-polarized light splitting sheet, and the polarization combining device 5 is a transmissive S-polarized light and reflective P-polarized light combining sheet. Figure 4 The light beam is split by the transmissive S-polarized light and reflective P-polarized light splitting sheet into first polarization S-light and second polarization P-light perpendicular to each other. The first polarization S-light passes through the transmissive S-polarized light and reflective P-polarized light splitting sheet and enters the first LCD assembly to modulate and form first modulated P-light, which is directed to the light-out side of the transmissive S-polarized light and reflective P-polarized light combining sheet and reflected into a preset light path. The second polarization P-light is reflected by the light-in side of the transmissive S-polarized light and reflective P-polarized light splitting sheet and then guided into the second LCD assembly to modulate and form second modulated S-light, which is directed to and passes through the transmissive S-polarized light and reflective P-polarized light combining sheet and enters the preset light path to combine with the first modulated P-light.

[0060] As shown in FIG. 2, in another embodiment, the polarization splitting device 2 is a transmissive P-polarized light and reflective S-polarized light splitting sheet, and the polarization combining device 5 is a transmissive P-polarized light and reflective S-polarized light combining sheet. Figure 5 The light beam is split by the transmissive P-polarized light and reflective S-polarized light splitting sheet into first polarization P-light and second polarization S-light perpendicular to each other. The first polarization P-light passes through the transmissive P-polarized light and reflective S-polarized light splitting sheet and enters the first LCD assembly to modulate and form first modulated S-light, which is directed to the light-out side of the transmissive P-polarized light and reflective S-polarized light combining sheet and reflected into a preset light path. The second polarization S-light is reflected by the light-in side of the transmissive P-polarized light and reflective S-polarized light splitting sheet and then guided into the second LCD assembly to modulate and form second modulated P-light, which is directed to and passes through the transmissive P-polarized light and reflective S-polarized light combining sheet and enters the preset light path to combine with the first modulated S-light.

[0061] In some embodiments, the polarization combining device 5 is arranged at an angle with the light beam, and the angle can be 15°-75°, which can satisfy the transmission of the first modulated light and the reflection of the second modulated light. Further, the angle can be 45°.

[0062] In some embodiments, the distance between the first LCD assembly and the projection lens and the distance between the second LCD assembly and the projection lens are equal to ensure the optical path and the on-screen effect.

[0063] The second LCD assembly can be a transmissive LCD or a reflective LCD. As shown in FIG. 3, the second LCD assembly is a reflective LCD.Figure 6 In the embodiment shown, the second LCD component is a reflective LCD, which includes a second polarizer 41, a third substrate 42, a second liquid crystal layer 43, a reflective layer 44, and a fourth substrate 45 stacked in sequence. In operation, polarized light is modulated by the second polarizer 41, the third substrate 42, and the second liquid crystal layer 43 in sequence, and then reflected on the reflective layer 44, reversely travels along the original light path, and exits through the second liquid crystal layer 43, the third substrate 42, and the second polarizer 41 in sequence. As shown in FIG. 1, the second LCD component is arranged on the out-light side of the polarization combining light device 5. Figure 7 In the embodiment shown, the second LCD component is a transmissive LCD, which includes a fifth substrate 46, a third liquid crystal layer 47, a sixth substrate 48, and a third polarizer 49 stacked in sequence. In operation, polarized light is modulated by the fifth substrate 46, the third liquid crystal layer 47, the sixth substrate 48, and the third polarizer 49 in sequence. The third substrate 42 can be a CF substrate, and the fourth substrate 45 can be a TFT substrate. The fifth substrate 46 can be a TFT substrate, and the sixth substrate 48 can be a CF substrate.

[0064] Based on the different implementation forms of the second LCD component, the second embodiment to the fifth embodiment of the optical system 100 are proposed.

[0065] Please refer to Figure 2 and Figure 3 In the second embodiment and the third embodiment, the second LCD component is a reflective LCD, which specifically includes a second polarizer 41, a third substrate 42, a second liquid crystal layer 43, a reflective layer 44, and a fourth substrate 45 stacked in sequence, and the second polarizer 41 is arranged close to the polarization combining light device 5. The reflective layer 44 is used to reflect the second modulated light to the out-light side of the polarization combining light device 5. In this embodiment, since the polarization light splitting device 2 is used for light splitting, the second LCD component can reduce one polarizer, which helps to further simplify the elements, reduce heat, improve heat dissipation and polarizer yellowing problem, improve the out-light brightness and effect, and improve the screen brightness and effect of the projection device 1000. At the same time, the reflective LCD is used as the second LCD component, and the reflective layer 44 can be used as a heat dissipation structure to quickly conduct heat away, further improving heat dissipation and light attenuation.

[0066] Further, in some specific embodiments, the first LCD component is located on the in-light side of the polarization combining light device 5 and forms a 45° angle with the polarization combining light device 5, and the second LCD component is located on the out-light side of the polarization combining light device 5 and forms a 45° angle with the polarization combining light device 5, so that the second modulated light reflected by the reflective layer 44 can be incident on the out-light side of the polarization combining light device 5 at a 45° angle, and then reflected on the out-light side to successfully combine with the first polarized light transmitted through the polarization combining light device 5.

[0067] To better guide the light beam propagation direction, make the light propagate in the expected direction, and reduce the volume of the optical system 100, the optical system 100 can further include a first mirror 61 disposed between the polarization beam splitter 2 and the first LCD assembly for reflecting the first polarized light to the first LCD assembly. In some embodiments, the first mirror 61 can be designed to be parallel to the polarization beam splitter 2, to be at a 45° angle with the first LCD assembly, and to be perpendicular to the polarization beam combiner 5, so as to guide the first polarized light transmitted or reflected by the polarization beam splitter 2 to be reflected on the first mirror 61, modulated by the first LCD assembly, and then to be incident on the light entrance side of the polarization beam combiner 5 at a 45° angle, thereby ensuring smooth combination with the second modulated light. In another embodiment, the optical system 100 can further include a second mirror 62 disposed between the polarization beam splitter 2 and the polarization beam combiner 5, and disposed on both sides of the second LCD assembly with respect to the polarization beam combiner 5. The second mirror 62 is directed toward the light entrance side of the polarization beam combiner 5, and the second LCD assembly is directed toward the light exit side of the polarization beam combiner 5, so as to reflect the second polarized light to the light entrance side of the polarization beam combiner 5, so that the second polarized light is incident on the second LCD assembly after passing through the polarization beam combiner 5, then reflected back to the light exit side of the polarization beam combiner 5 via the reflection layer 44 after being modulated by the second LCD assembly, and combined with the first modulated light passing through the polarization beam combiner 5 on the light exit side. In some embodiments, the second mirror 62 can be designed to be parallel to the polarization beam splitter 2, to be at a 45° angle with the second LCD assembly, and to be perpendicular to the polarization beam combiner 5, so as to guide the second polarized light transmitted or reflected by the polarization beam splitter 2 to be reflected on the second mirror 62, to pass through the polarization beam combiner 5, to be modulated by the second LCD assembly, to return to the original path, and to be incident on the light exit side of the polarization beam combiner 5 at a 45° angle, thereby ensuring that the reflected light path on the light exit side can be smoothly combined with the first modulated light.

[0068] In some embodiments, the distance between the polarization beam splitter 2 and the first mirror 61 can be set to be equal to the distance between the polarization beam splitter 2 and the second mirror 62, so as to ensure equal optical path lengths.

[0069] Further, in some embodiments, the optical system 100 can further comprise a first Fresnel lens 71, which is arranged between the polarization combining device 5 and the second LCD assembly, and the Fresnel surface of the first Fresnel lens 71 is arranged towards the second LCD assembly. It can be understood that the first Fresnel lens 71 is a Fresnel lens, which has a back surface and a Fresnel surface arranged oppositely, wherein the Fresnel surface is usually formed with a plurality of teeth arranged circumferentially and concentrically along the central axis of the Fresnel lens, and the back surface is the side surface of the Fresnel lens opposite to the Fresnel surface. By arranging the first Fresnel lens 71, the light rays can be collimated. The first Fresnel lens 71 can also be arranged between the polarization splitting device 2 and the second mirror 62, or between the second mirror 62 and the polarization combining device 5. However, compared with the arrangement of the first Fresnel lens 71 between the polarization combining device 5 and the second LCD assembly, the light rays can be better collimated, the light emission can be reduced, and thus the volume of the optical system 100 can be reduced.

[0070] Further, in some embodiments, the distance between the first Fresnel lens 71 and the second LCD assembly can be 10-50 mm, which can help to improve the collimation effect.

[0071] Please refer to Figure 4 and Figure 5 In the fourth and fifth embodiments, the second LCD assembly is a transmissive LCD, which specifically comprises a fifth substrate 46, a third liquid crystal layer 47, a sixth substrate 48 and a third polarizer 49 stacked in sequence, and the third polarizer 49 is arranged close to the polarization combining device 5. In this embodiment, since the polarization splitting device 2 is used for splitting light, the second LCD assembly can reduce one polarizer, which can help to further simplify components, reduce heat generation, improve heat dissipation and polarizer yellowing problem, improve light output brightness and effect, and improve the screen brightness and effect of the projection device 1000.

[0072] To better guide the light beam propagation direction, make the light propagate in the expected direction, and reduce the volume of the optical system 100, the optical system 100 can further comprise a third mirror 63, which is arranged between the polarization beam splitter 2 and the first LCD assembly, so that the first polarized light can be reflected to the first LCD assembly. In some embodiments, the third mirror 63 can be designed to be parallel to the polarization beam splitter 2, at a 45° angle with the first LCD assembly, and parallel to the polarization beam combiner 5, so that the first polarized light transmitted or reflected by the polarization beam splitter 2 is reflected on the third mirror 63, then vertically enters the first LCD assembly, and then is incident on the light entrance side of the polarization beam combiner 5 at a 45° angle, thereby ensuring smooth combination with the second modulated light. In other embodiments, the optical system 100 can further comprise a fourth mirror 64, which is arranged between the polarization beam splitter 2 and the second LCD assembly, and is located on the light exit side of the polarization beam combiner 5, so that the second polarized light can be reflected to the second LCD assembly. In some embodiments, the fourth mirror 64 can be designed to be parallel to the polarization beam splitter 2, at a 45° angle with the second LCD assembly, and parallel to the polarization beam combiner 5, so that the second polarized light transmitted or reflected by the polarization beam splitter 2 is reflected on the fourth mirror 64, then vertically enters the second LCD assembly, and then is incident on the light exit side of the polarization beam combiner 5 at a 45° angle, thereby ensuring smooth combination with the first modulated light.

[0073] In some embodiments, the distance between the polarization beam splitter 2 and the third mirror 63 can be set to be equal to the distance between the polarization beam splitter 2 and the fourth mirror 64, to ensure equal optical path.

[0074] The optical system 100 can further comprise a second Fresnel mirror 72 and a third Fresnel mirror 73, both of which are Fresnel lenses having respective back surfaces and Fresnel surfaces. The second Fresnel mirror 72 is arranged between the second LCD assembly and the polarization beam splitter 2, for collimating light rays and correcting incident light rays to parallel light; the back surface of the second Fresnel mirror 72 serves as the light entrance side, and the Fresnel surface serves as the light exit side. The third Fresnel mirror 73 is arranged between the second LCD assembly and the polarization beam combiner 5, for collimating light rays and correcting aberrations; the Fresnel surface of the third Fresnel mirror 73 serves as the light entrance side, and the back surface serves as the light exit side.

[0075] Further, in some embodiments, the distance between the second Fresnel lens 72 and the second LCD assembly can be 10-50mm, and the distance between the third Fresnel lens 73 and the second LCD assembly can be 10-50mm, which helps to improve the collimation effect, reduce the heat of the second LCD assembly, and improve heat dissipation.

[0076] To improve the display effect, the optical system 100 can further include a fourth Fresnel lens 74 and a fifth Fresnel lens 75. The fourth Fresnel lens 74 and the fifth Fresnel lens 75 are both Fresnel lenses, each having a back surface and a Fresnel surface. The fourth Fresnel lens 74 is arranged between the polarization beam splitter 2 and the first LCD assembly, and is used to collimate the light and correct the incident light to be parallel light. The back surface of the fourth Fresnel lens 74 serves as the light entrance side, and the Fresnel surface serves as the light exit side. The fifth Fresnel lens 75 is arranged between the first LCD assembly and the polarization beam combiner 5, and is used to collimate the light and correct the aberration. The Fresnel surface of the fifth Fresnel lens 75 serves as the light entrance side, and the back surface serves as the light exit side. That is, in the present embodiment, the light emitted by the light source 1 enters the polarization beam splitter 2 and is divided into first polarized light and second polarized light. The first polarized light is guided to enter the back surface of the fourth Fresnel lens 74 and exit from the Fresnel surface, and then enters the first LCD assembly to form first modulated light, which then enters the Fresnel surface of the fifth Fresnel lens 75 and exits from the back surface.

[0077] Further, in some embodiments, the distance between the fourth Fresnel lens 74 and the first LCD assembly can be 10-50mm, and the distance between the fifth Fresnel lens 75 and the first LCD assembly can be 10-50mm, which helps to improve the collimation effect, reduce the heat of the first LCD assembly, and improve heat dissipation.

[0078] When the optical system 100 further includes a third mirror 63 and a fourth mirror 64, the second Fresnel lens 72 can be arranged between the polarization beam splitter 2 and the fourth mirror 64, or between the fourth mirror 64 and the second LCD assembly. The fourth Fresnel lens 74 can be arranged between the polarization beam splitter 2 and the third mirror 63, or between the third mirror 63 and the first LCD assembly. However, compared with the arrangement of the second Fresnel lens 72 between the fourth mirror 64 and the second LCD assembly and the arrangement of the fourth Fresnel lens 74 between the third mirror 63 and the first LCD assembly, the arrangement helps to better collimate the light and reduce the light emission, thereby reducing the volume of the optical system 100.

[0079] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments. In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can be explicitly or implicitly included one or more features.

[0080] The above describes the technical solutions provided by the embodiments of the present application in detail, and the principles and implementation manners of the present application are described by applying specific examples. The above embodiment description is only for helping to understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will have changes, and in view of the above, the content of the specification should not be understood as limiting the present application.

Claims

1. An optical system characterized by comprising: The optical system comprises: a light source for emitting light; a polarization splitting device for splitting the light into first polarized light and second polarized light; a first LCD assembly for modulating the first polarized light to form first modulated light, wherein the first LCD assembly comprises a first substrate, a first liquid crystal layer, a second substrate and a first polarizer which are sequentially stacked along an optical path direction. The optical system further comprises:

2. The optical system of claim 1, wherein a second LCD assembly for modulating the second polarized light to form second modulated light; and a polarization combining device having an entrance side facing the first LCD assembly and an exit side facing the second LCD assembly, the polarization combining device being configured to combine the first modulated light and the second modulated light and output the combined light. The polarization splitting device is a S-passing and P-reflection splitting polarizer, and the polarization combining device is a S-passing and P-reflection combining polarizer; or 3. The optical system of claim 2, wherein, The polarization splitting device is a P-passing and S-reflection splitting polarizer, and the polarization combining device is a P-passing and S-reflection combining polarizer. The second LCD assembly comprises a second polarizer, a third substrate, a second liquid crystal layer, a reflective layer and a fourth substrate which are sequentially stacked, and the second polarizer is arranged close to the polarization combining device, wherein the reflective layer is configured to reflect the second modulated light to the exit side of the polarization combining device.

4. The optical system of claim 2, wherein The optical system further comprises a first mirror arranged between the polarization splitting device and the first LCD assembly and configured to reflect the first polarized light to the first LCD assembly; and / or 5. The optical system of claim 4, wherein, The optical system further comprises a second mirror arranged between the polarization splitting device and the polarization combining device and facing the entrance side of the polarization combining device, and configured to reflect the second polarized light to the entrance side of the polarization combining device so that the second polarized light passes through the polarization combining device and enters the second LCD assembly. The optical system further comprises a first Fresnel mirror arranged between the polarization combining device and the second LCD assembly, and a Fresnel surface of the first Fresnel mirror faces the second LCD assembly.

6. The optical system of claim 4, wherein, The second LCD assembly comprises a fifth substrate, a third liquid crystal layer, a sixth substrate and a third polarizer which are sequentially stacked, and the third polarizer is arranged close to the polarization combining device.

7. The optical system of claim 2, wherein The optical system further comprises a third mirror arranged between the polarization splitting device and the first LCD assembly and configured to reflect the first polarized light to the first LCD assembly; and / or 8. The optical system of claim 7, wherein, The optical system further comprises a fourth mirror arranged between the polarization splitting device and the second LCD assembly and located at the exit side of the polarization combining device, and configured to reflect the second polarized light to the second LCD assembly; and / or The optical system further comprises a second Fresnel mirror arranged between the second LCD assembly and the polarization splitting device, and a third Fresnel mirror arranged between the second LCD assembly and the polarization combining device. The optical system further comprises:

9. The optical system of claim 2, wherein, ​ a fourth Fresnel mirror disposed between the first LCD assembly and the polarization splitting device; and a fifth Fresnel mirror disposed between the first LCD assembly and the polarization combining device.

10. A projection apparatus, characterized by, comprising: the optical system of any one of claims 1-9; and a projection lens for receiving light output by the optical system.

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