Polarization modulation device and method for stereoscopic projection light and stereoscopic image projection system

Abstract

The present invention discloses a polarization modulation device and method for stereoscopic projection light and a stereoscopic image projection system. The device comprises a polarization beam splitting component, a first optical path direction adjustment component, a second optical path direction adjustment component and a polarization state modulation component. The polarization beam splitting component can split a projection light beam carrying image information into a first transmission light beam, a second transmission light beam, a first reflection light beam and a second reflection light beam with four different polarization states or three different polarization states. Compared with the prior art, the present invention can effectively reduce the optical path difference between the reflection light beam and the transmission light beam by splitting a light beam corresponding to a complete image screen into two reflection light beams when polarizing, compared with a dual-optical path polarization splitting method with only one reflection light beam, so that the subsequent optical path direction adjustment component and the optical path compensation component can be selected to have a smaller size, thereby greatly reducing the volume of the entire device.

Description

Technical Field

[0001] The present invention belongs to the field of projection display technology, and in particular relates to a polarization modulation device and method for stereoscopic projection light and a stereoscopic image projection system. Background Art

[0002] The principle of viewing stereoscopic images is that the left and right eyes of a person respectively receive the left and right eye video images played in frame order, and then the left and right eye video images are synthesized through the brain to produce a stereoscopic effect.

[0003] At present, the main technologies for receiving images by the left and right eyes include left-right polarization splitting, left-right shutter switch synchronization, and left-right red and blue splitting. Among them, the left-right polarization splitting is more widely used. In the left-right polarization splitting methods, single-path polarization splitting technology and dual-path polarization splitting technology have been produced in accordance with the technology development trajectory.

[0004] A typical single-path polarization splitting principle is as follows: Figure 1 As shown, the projector 11 projects a projection beam carrying a left-eye image and a projection beam carrying a right-eye image in sequence according to the frame sequence. The projection beam is polarized by the polarizer 12 and converted into linear polarized light. Then, the polarization modulator 13 modulates the left-handed circularly polarized light and the right-handed circularly polarized light according to the frame sequence and projects them onto the screen 15. The left and right eyes of the audience receive the left-handed circularly polarized light and the right-handed circularly polarized light reflected by the screen 15 through the circularly polarized glasses 16 they wear, respectively. The synchronization circuit 14 is used to control the projector 11 and the polarization modulator 13 to work synchronously. However, since the polarizer 12 is an absorption type, only part of the light energy is polarized and the other part of the light energy is discarded during the polarization process, so that a large amount of light energy is converted into heat on the polarizer 12. When using a high-brightness movie projector, the temperature of the polarizer 12 will rise rapidly, which will accelerate the aging speed of the polarizer 12 and significantly deteriorate the optical performance. In severe cases, the strong light beam will burn the polarizer 12. Therefore, the single-path polarization splitting was later replaced by the dual-path polarization splitting.

[0005] The principle of dual-path polarization splitting is as follows Figure 2 As shown, it is mainly realized based on an inclined plate type beam splitter prism, which has an inclined polarization beam splitter film 2. The projection light beam from the projector is split into transmitted P polarized light and reflected S polarized light by the polarization beam splitter film, and then the P polarized light is converted into S polarized light or the S polarized light is converted into P polarized light, and finally the two beams are uniformly modulated into left-handed circularly polarized light or right-handed circularly polarized light according to the frame sequence. Since the projection light is fully utilized in the polarization process, the utilization rate of the projection light and the brightness of the projection picture are also improved.

[0006] However, the modulation system using dual-path polarization splitting will be larger in size, the required optical devices will also be larger, and there will be many difficulties in device processing and assembly. Summary of the invention

[0007] The main purpose of the embodiments of the present invention is to provide a polarization modulation device and method for stereoscopic projection light and a stereoscopic image projection system, which can solve the technical problem that the existing stereoscopic projection polarization light modulation device based on dual-light path polarization splitting technology is large in size.

[0008] In order to solve the above technical problems, a first aspect of an embodiment of the present invention provides a polarization modulation device for stereoscopic projection light, the device comprising:

[0009] A polarization beam splitting component, used for splitting the projection light beam carrying image information into a first transmission light beam, a second transmission light beam, a first reflection light beam and a second reflection light beam having four different polarization states, or having three different polarization states;

[0010] A first optical path direction adjustment component, used for adjusting a propagation direction of the first reflected light beam so that the first reflected light beam propagates in a direction where an imaging surface is located;

[0011] A second optical path direction adjustment component, used for adjusting a propagation direction of the second reflected light beam so that the second reflected light beam propagates in a direction where the imaging surface is located;

[0012] The polarization state modulation component is used to modulate the polarization state of part or all of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam in frame sequence.

[0013] Optionally, the polarization beam splitting component includes two substrates, the two substrates are connected to each other in a V-shape, and a ridge formed by the connection has a protruding direction opposite to a propagation direction of the projection light beam;

[0014] A first polarization splitting layer and a second polarization splitting layer are provided on the two substrates. When the projection light beam is projected onto the two substrates, the first polarization splitting layer can transmit the first transmitted light beam and reflect the first reflected light beam, and the second polarization splitting layer can transmit the second transmitted light beam and reflect the second reflected light beam.

[0015] Optionally, the polarization beam splitting component is a polarization beam splitting prism group; the polarization beam splitting prism group is formed by bonding at least three prisms, and a first polarization beam splitting layer and a second polarization beam splitting layer are formed at the bonding point, the first polarization beam splitting layer and the second polarization beam splitting layer are connected to each other in a V-shape, and a ridge formed by the connection protrudes in a direction opposite to a propagation direction of the projection light beam, and when the projection light beam is projected onto the polarization beam splitting prism group, the first polarization beam splitting layer can transmit the first transmitted light beam and reflect the first reflected light beam, and the second polarization beam splitting layer can transmit the second transmitted light beam and reflect the second reflected light beam.

[0016] Optionally, the first polarization splitting layer is a wire grid structure, and the second polarization splitting layer is formed by stacking several layers of optical films; or, the first polarization splitting layer and the second polarization splitting layer are both formed by stacking several layers of optical films, the polarization direction of the first reflected light beam is orthogonal to the polarization direction of the first transmitted light beam, and one of the second transmitted light beam and the second reflected light beam has a polarization direction that is the same as the polarization direction of the first transmitted light beam or the first reflected light beam, and the angle between the polarization direction of the second reflected light beam and the polarization direction of the second transmitted light beam is in the range of (0°, 90°).

[0017] Optionally, an angle between the polarization direction of the second reflected light beam and the polarization direction of the second transmitted light beam is 45°.

[0018] Optionally, the polarization state modulation component includes a first polarization state converter, a second polarization state converter and an optical modulator;

[0019] The first polarization state converter and the second polarization state converter are respectively located in the optical path where the first reflected light beam and the second reflected light beam are located, or respectively located in the optical path where the first reflected light beam and the second transmitted light beam are located, or respectively located in the optical path where the first transmitted light beam and the second transmitted light beam are located, or respectively located in the optical path where the first transmitted light beam and the second reflected light beam are located, and are used to adjust the polarization states of the light beams passing through the first polarization state converter and the second polarization state converter so that the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam are the same;

[0020] The optical modulator is used to modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam having the same polarization state into left-handed circularly polarized light and right-handed circularly polarized light in a frame sequence.

[0021] Optionally, the first polarization splitting layer and the second polarization splitting layer are both wire grid structures, and the angle between the wire grid arrangement direction of the first polarization splitting layer and the wire grid arrangement direction of the second polarization splitting layer is in the range of (0°, 90°); or, the first polarization splitting layer and the second polarization splitting layer are both formed by stacking several layers of optical films; wherein, the angle between the polarization direction of the first transmitted light beam and the polarization direction of the second transmitted light beam is in the range of (0°, 90°), the polarization direction of the first reflected light beam is orthogonal to the polarization direction of the first transmitted light beam, and the polarization direction of the second reflected light beam is orthogonal to the polarization direction of the second transmitted light beam.

[0022] Optionally, an angle between a wire grid arrangement direction of the first polarization splitting layer and a wire grid arrangement direction of the second polarization splitting layer is 45°; wherein an angle between a polarization direction of the first transmitted light beam and a polarization direction of the second transmitted light beam is 45°.

[0023] Optionally, the polarization state modulation component includes a first polarization state converter, a second polarization state converter, a third polarization state converter and an optical modulator;

[0024] The first polarization state converter, the second polarization state converter and the third polarization state converter are located in the optical path of any three of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam, and are used to adjust the polarization states of the light beams passing through the first polarization state converter, the second polarization state converter and the third polarization state converter so that the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam are the same;

[0025] The optical modulator is used to modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam having the same polarization state into left-handed circularly polarized light and right-handed circularly polarized light in a frame sequence.

[0026] Optionally, the first polarization state converter is located in the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam into a first target polarization state; the second polarization state converter is attached to the first polarization beam splitting layer in the polarization beam splitting component, and is located on the side of the first polarization beam splitting layer that can transmit the first transmitted light beam, and is used to convert the polarization state of the first transmitted light beam into the first target polarization state; the third polarization state converter is located in the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam into the first target polarization state, and the first target polarization state is the same as the polarization state of the second transmitted light beam;

[0027] Alternatively, the first polarization state converter is located in the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam into a second target polarization state. The second polarization state converter is attached to the second polarization splitting layer in the polarization beam splitting component and is located on the side of the second polarization splitting layer that can transmit the second transmitted light beam, and is used to convert the polarization state of the second transmitted light beam into the second target polarization state. The third polarization state converter is located in the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam into the second target polarization state, and the second target polarization state is the same as the polarization state of the first transmitted light beam.

[0028] In order to solve the above technical problems, a second aspect of an embodiment of the present invention provides a stereoscopic image projection system, the system comprising:

[0029] A projector, used to sequentially project a projection light beam carrying left-eye image information and a projection light beam carrying right-eye image information in a frame sequence;

[0030] A polarization modulation device, wherein the polarization modulation device is the polarization modulation device for stereoscopic projection light provided in the second aspect of the embodiment of the present invention;

[0031] The screen is used for imaging each projection light beam with the same polarization state modulated by the polarization modulation device of the stereoscopic projection light, and reflecting the formed image to the 3D glasses worn by the user.

[0032] In order to solve the above technical problems, a third aspect of an embodiment of the present invention provides a polarization modulation method for stereoscopic projection light, the method comprising the following steps:

[0033] Splitting the projection light beam carrying image information into a first transmission light beam, a second transmission light beam, a first reflection light beam and a second reflection light beam having four different polarization states or three different polarization states;

[0034] Adjusting the propagation directions of the first reflected light beam and the second reflected light beam so that the first reflected light beam and the second reflected light beam propagate in the direction where the imaging surface is located;

[0035] Polarization states of part or all of the first transmitted light beam, the second transmitted light beam, the first reflected light beam, and the second reflected light beam are modulated in a frame sequence.

[0036] The embodiment of the present invention provides a polarization modulation device for stereoscopic projection light. Compared with the prior art, the projection polarization modulation device for stereoscopic light provided by the embodiment of the present invention uses a polarization splitting component to split the projection light beam into four light beams with four different polarization states or three different polarization states, including two transmitted light beams and two reflected light beams. The embodiment of the present invention divides the light beam corresponding to a complete image into two reflected light beams when polarizing. Compared with a dual-path polarization splitting method with only one reflected light beam, the optical path difference between the reflected light beam and the transmitted light beam can be effectively reduced, so that the subsequent optical path direction adjustment component and the optical path compensation component can be selected to be smaller in size, thereby greatly reducing the volume of the entire device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the principle of a stereoscopic image projection system provided by the prior art using single light path polarization splitting;

[0038] Figure 2 It is a schematic diagram of the principle of a stereoscopic image projection system provided by the prior art using dual-light path polarization splitting;

[0039] Figure 3 is a structural principle diagram of a polarization modulation device for stereoscopic projection light provided by a first embodiment of the present invention;

[0040] Figure 4A is a structural principle diagram of a polarization modulation device for stereoscopic projection light provided by a second embodiment of the present invention;

[0041] Figure 4B is another structural principle diagram of the polarization modulation device for stereoscopic projection light provided by the second embodiment of the present invention;

[0042] Figure 5 is a structural principle diagram of a polarization beam splitting component in the form of a prism group structure provided by a second embodiment of the present invention;

[0043] Fig. 6A and Figure 6B is a structural principle diagram of a polarization modulation device for stereoscopic projection light provided by a third embodiment of the present invention;

[0044] Fig. 7A and Figure 7B They are schematic diagrams of the wire grid structure of the polarization splitting layer on the first substrate provided by the third embodiment of the present invention;

[0045] Fig. 8A and Figure 8B They are schematic diagrams of the wire grid structure of the polarization splitting layer on the second substrate provided by the third embodiment of the present invention;

[0046] Fig. 9is a structural principle diagram of a polarization beam splitting component in the form of a prism group structure provided by a third embodiment of the present invention;

[0047] Fig. 10A and Fig. 10B They are schematic diagrams of wire grid structures of two polarization beam splitting layers in a polarization beam splitting component in the form of a prism group structure provided in the third embodiment of the present invention;

[0048] Fig.11 is a schematic diagram of a light path of two transmitted light beams having mixed polarization regions provided by a third embodiment of the present invention;

[0049] Fig. 12A and Fig. 12B is a structural principle diagram of a polarization modulation device for stereoscopic projection light provided by a fourth embodiment of the present invention;

[0050] Fig.13 It is a structural principle diagram of a polarization beam splitting component in the form of a prism group structure provided in the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0052] See also Figure 3 , Figure 3 1 is a schematic diagram of the structure of the polarization modulation device for stereoscopic projection light provided by the first embodiment of the present invention. In the first embodiment of the present invention, the polarization modulation device for stereoscopic projection light comprises: a polarization beam splitting component 31, a first optical path direction adjustment component 32, a second optical path direction adjustment component 33 and a polarization state modulation component 34. The functions of each component are described as follows:

[0053] Polarization beam splitting component 31: used to split the projection beam carrying image information into a first transmission beam, a second transmission beam, a first reflection beam and a second reflection beam with four different polarization states, or three different polarization states. For example, the polarization beam splitting component 31 can split the projection beam carrying image information into a first transmission beam with a first polarization state, a second transmission beam with a second polarization state, a first reflection beam with a third polarization state and a second reflection beam with a fourth polarization state, wherein the polarization directions of the first polarization state, the second polarization state, the third polarization state and the fourth polarization state are different from each other; or, split the projection beam carrying image information into a first transmission beam and a second transmission beam with a first polarization state, a first reflection beam with a second polarization state and a second reflection beam with a third polarization state, wherein the polarization directions of the first polarization state, the second polarization state and the third polarization state are different from each other.

[0054] The polarization modulation device for stereoscopic projection light provided by the embodiment of the present invention is placed between the projector and the imaging surface (i.e., the screen) when in use, and is used to perform an optical effect on the projection light beam projected by the projector, so that the projection light beam has a uniform polarization state such as linear polarization or circular polarization before being projected onto the imaging surface. The imaging surface then reflects the projection light beam with the polarization state to the 3D glasses worn by the audience, wherein the imaging surface needs to have a polarization-maintaining characteristic, that is, the imaging surface cannot change the polarization state of the projection light beam during the process of reflecting the projection light beam, which is usually achieved by using a metal screen.

[0055] First, the projector alternately projects a projection beam carrying left-eye image information and a projection beam carrying right-eye image information, for example, in a frame order, similar to playing a video, projecting a projection beam carrying left-eye image information at time T1, projecting a projection beam carrying right-eye image information at time T2, projecting a projection beam carrying left-eye image information at time T3, projecting a projection beam carrying right-eye image information at time T4, and so on. From a hardware perspective, the projector is required to support video playback with a frame frequency of 100 Hz or higher, and a digital micromirror projector, a liquid crystal on silicon projector, etc. may be used.

[0056] Then, the polarization beam splitting component 31 performs polarization beam splitting on the projection beam. In the embodiment of the present invention, the polarization beam splitting component 31 splits the projection beam into four beams, namely, a first transmitted beam, a first reflected beam, a second transmitted beam, and a second reflected beam. The first transmitted beam and the second transmitted beam propagate directly in the direction of the imaging surface, and the propagation direction of the first reflected beam is perpendicular to the propagation direction of the corresponding first transmitted beam due to reflection. Similarly, the propagation direction of the second reflected beam is perpendicular to the propagation direction of the corresponding second transmitted beam due to reflection. Therefore, the first optical path direction adjusting component 32 and the second optical path direction adjusting component 33 are required to adjust the propagation directions of the first reflected beam and the second reflected beam respectively, so that the first reflected beam and the second reflected beam can propagate in the direction of the imaging surface.

[0057] The first transmitted light beam carries the same image information as the first reflected light beam and has the same imaging position on the imaging surface. Correspondingly, the second transmitted light beam carries the same image information as the second reflected light beam and has the same imaging position on the imaging surface.

[0058] It should be emphasized that since the first transmitted light beam and the second transmitted light beam are both propagated directly in the direction of the imaging surface after being split, they appear to be a whole beam of light macroscopically, but since their polarization states may be different, they should be understood as two different beams in essence. Figure 3 The propagation paths of the first transmitted light beam and the second transmitted light beam are only schematically shown. In fact, since the projection light beam projected by the projector is divergent, the first transmitted light beam and the second transmitted light beam obtained after the projection light beam is split by the polarization beam splitter 31 are still divergent, so that the first transmitted light beam and the second transmitted light beam will partially overlap in the imaging area of ​​the imaging surface.

[0059] Among them, the above-mentioned first polarization state, second polarization state, third polarization state and fourth polarization state are all linear polarizations. For example, the polarization direction of the first polarization state is horizontal, the value interval of the angle between the polarization direction of the second polarization state and the horizontal direction is (0°, 90°), the third polarization state is orthogonal to the polarization direction of the first polarization state, and the fourth polarization state is orthogonal to the polarization direction of the second polarization state. A preferred situation is that the polarization direction of the first polarization state is horizontal (P polarized light), the angle between the polarization direction of the second polarization state and the horizontal direction is 45°, then the polarization direction of the third polarization state is vertical (S polarized light), and the angle between the polarization direction of the fourth polarization state and the horizontal direction is -45°.

[0060] The polarization beam splitting component 31 can use a polarization splitting film formed by stacking several layers of optical films to perform beam splitting and polarization, or use an optical wire grating to perform beam splitting and polarization, or use a polarization splitting film and an optical wire grating structure to perform beam splitting and polarization at the same time. For example, a polarization splitting film is used to split the first transmitted light beam and the first reflected light beam, and an optical wire grating structure is used to split the second transmitted light beam and the second reflected light beam.

[0061] The first optical path direction adjusting component 32 is used to adjust the propagation direction of the first reflected light beam so that the first reflected light beam propagates in the direction where the imaging surface is located.

[0062] The adjustment direction of the first optical path direction adjusting component 32 can make the imaging position of the first reflected light beam finally on the imaging surface overlap with the imaging position of the first transmitted light beam. In specific implementation, the adjustment direction of the first optical path direction adjusting component 32 can be set to be adjustable to facilitate adjusting the imaging position of the first reflected light beam on the imaging surface. It can usually be achieved by using a device with a reflective function, such as a plane mirror, a curved mirror that can expand or reduce the size of the light beam, etc. Of course, it can also be achieved by using an optical device that can change the direction of the optical path, such as a lens.

[0063] The second optical path direction adjusting component 33 is used to adjust the propagation direction of the second reflected light beam so that the second reflected light beam propagates in the direction where the imaging surface is located.

[0064] Similarly, the adjustment direction of the second optical path direction adjustment component 33 can make the imaging position of the second reflected light beam finally overlap with the imaging position of the second transmitted light beam on the imaging surface. In specific implementation, the adjustment direction of the second optical path direction adjustment component can be set to be adjustable to facilitate adjusting the imaging position of the second reflected light beam 33 on the imaging surface. It can usually be achieved by using a plane mirror, a curved mirror that can expand or reduce the size of the light beam, and other devices with a reflective function. Of course, it can also be achieved by using an optical device such as a lens that can change the direction of the light path.

[0065] Polarization state modulation component 34: used to modulate the polarization state of part or all of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam in frame sequence so that the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam have the same polarization state.

[0066] The polarization state modulation component 34 modulates the four beams of light into a polarization state that can only be received by the left eye and a polarization state that can only be received by the right eye in sequence according to the frame order. For example, in the current frame, the four beams of light are modulated into a polarization state that can be received by the left eye but not by the right eye, and in the next frame, the four beams of light are modulated into a polarization state that can be received by the right eye but not by the left eye.

[0067] However, within any frame, the polarization states of the four light beams need to be modulated to be consistent before reaching the imaging surface. During the specific modulation, only the polarization states of part of the light beams can be modulated. For example, no matter whether it is playing the image frame corresponding to the left eye image or the image frame corresponding to the right eye image, the polarization state modulation component 34 modulates the polarization states of the second transmitted light beam, the first reflected light beam and the second reflected light beam into the polarization state of the first transmitted light beam, so that the four light beams have the same polarization state; the four light beams can also be made to participate in the polarization state modulation process. For example, when playing the image frame corresponding to the left eye image, the polarization state modulation component 34 modulates the polarization states of the second transmitted light beam, the first reflected light beam and the second reflected light beam into the polarization state of the first transmitted light beam, so that the four light beams have the same polarization state; and when playing the image frame corresponding to the right eye image, the polarization state modulation component 34 modulates the polarization states of the first transmitted light beam, the second transmitted light beam and the second reflected light beam into the polarization state of the first reflected light beam, so that the four light beams have the same polarization state.

[0068] As described above, the polarization states of the four beams of light split by the polarization beam splitting component 31 are uniformly converted into the same linear polarization state. Therefore, if the audience wears linear polarized glasses, the polarization state modulation component only needs to modulate the four beams of light into the same linear polarization state in each frame. If the audience wears circular polarized glasses, it is necessary to further modulate them into left-handed circularly polarized light and right-handed circularly polarized light. When it is necessary to modulate into circularly polarized light, the polarization state modulation component 34 needs to include: a polarization state converter and an optical modulator.

[0069] Among them, the polarization state converter needs to modulate the four beams of light into a uniform linear polarization state in each frame. Based on the principles described above, the polarization state converter has two working modes:

[0070] Mode 1: The polarization state converter modulates the polarization state of part of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam so that the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam have the same polarization state.

[0071] Mode 2: The polarization state converter modulates the polarization state of a portion of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam in a frame sequence.

[0072] Then, the light modulator modulates the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam with the same polarization state into left-handed circularly polarized light and right-handed circularly polarized light in frame sequence.

[0073] In addition, the optical modulator can also modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam, and the second reflected light beam having the same polarization state into left-handed elliptically polarized light and right-handed elliptically polarized light in a frame sequence, wherein the polarization direction of the left-handed circularly polarized light is orthogonal to the polarization direction of the right-handed circularly polarized light, and the polarization direction of the left-handed elliptically polarized light is orthogonal to the polarization direction of the right-handed elliptically polarized light.

[0074] When the polarization state converter works in the above-mentioned mode 1, devices such as wave plates and TN liquid crystal cells can be selected for implementation.

[0075] The above-mentioned light modulator can be implemented by a device with a quarter-wavelength delay function, such as a liquid crystal device or a quarter-wave plate. The four light paths can share one light modulator, or a light modulator can be set on each of the four light paths.

[0076] To summarize, in the first embodiment, since the projection light beam corresponding to a complete image is split into two reflected light beams by the polarization beam splitting component 31 when polarized, the optical path difference between the reflected light beam and the transmitted light beam is effectively reduced, so that the subsequent optical path direction adjustment component and the optical path compensation component can be of smaller size, thereby greatly reducing the size of the entire device.

[0077] The structure and position of the polarization beam splitter 31 and the polarization state converter in the first embodiment of the present invention can be designed in a variety of ways, as long as the above optical functions can be met. Several embodiments are listed below for explanation and description. It should be understood that in specific implementation, those skilled in the art can also flexibly change various other implementation schemes based on the present invention as needed.

[0078] Figure 4A A polarization modulation device for stereoscopic projection light according to a second embodiment of the present invention is shown. The polarization beam splitting component in this embodiment is used to split the projection light beam carrying image information into a first transmitted light beam, a second transmitted light beam, a first reflected light beam and a second reflected light beam with three different polarization states, which is suitable for situations where the audience wears circularly polarized glasses.

[0079] In this embodiment, the polarization beam splitting component includes a first substrate 3111 and a second substrate 3112, the two substrates are connected to each other in a V shape, and a ridge A1 is formed at the connected position, and the protruding direction of the ridge A1 is opposite to the propagation direction of the projection light beam, that is, the protruding direction of the ridge A1 is toward the projector. When used specifically, it is best to place the ridge A1 on the center line of the projection light beam. The first substrate 3111 is provided with a first polarization beam splitting layer, and the second substrate 3112 is provided with a second polarization beam splitting layer. When the projection light beam is projected onto the above two substrates, the first polarization beam splitting layer on the first substrate 3111 can transmit a first transmission light beam and reflect a first reflection light beam, and the second polarization beam splitting layer on the second substrate 3112 can transmit a second transmission light beam and reflect a second reflection light beam.

[0080] The function of the first optical path direction adjustment component 321 in this embodiment is the same as that of the first optical path direction adjustment component 32 in the first embodiment, and the function of the second optical path direction adjustment component 331 in this embodiment is the same as that of the second optical path direction adjustment component 33 in the first embodiment, and the details are not repeated here.

[0081] Among them, the above-mentioned polarization splitting layer is composed of several layers of optical films stacked together. In practical applications, these layers of optical films can be attached to a glass plate for use. When the projection light beam passes through these layers of optical films, it can be split into a transmission light beam and a reflection light beam with different polarization directions. For example, it can be split into a transmission light beam with a vertical polarization direction and a reflection light beam with an angle of 45° between the polarization direction and the vertical direction.

[0082] Please refer again Figure 4A ,exist Figure 4A In the figure, “①” indicates that the light beam is in a linear polarization state and has a first polarization state; “②” indicates that the light beam is in a linear polarization state and has a second polarization state; “③” indicates that the light beam is in a linear polarization state and has a third polarization state; and “●” indicates that the light beam is in a circular polarization state.

[0083] Among them, the polarization direction of the first reflected light beam is orthogonal to the polarization direction of the first transmitted light beam, and the polarization direction of one of the second transmitted light beam and the second reflected light beam is the same as the polarization direction of the first transmitted light beam or the first reflected light beam, and the value range of the angle between the polarization direction of the second reflected light beam and the polarization direction of the second transmitted light beam is (0°, 90°), and the angle can be preferably 45°; or, the polarization direction of the second reflected light beam is orthogonal to the polarization direction of the second transmitted light beam, and the polarization direction of one of the first transmitted light beam and the first reflected light beam is the same as the polarization direction of the second transmitted light beam or the second reflected light beam, and the value range of the angle between the polarization direction of the first reflected light beam and the polarization direction of the first transmitted light beam is (0°, 90°), and the angle can be preferably 45°. Figure 4AIn the embodiment, the polarization direction of the first reflected light beam is orthogonal to the polarization direction of the first transmitted light beam, the polarization direction of the second transmitted light beam is the same as the polarization direction of the first transmitted light beam, and the value interval of the angle between the polarization directions of the second reflected light beam and the second transmitted light beam is (0°, 90°); or, the polarization direction of the second reflected light beam is orthogonal to the polarization direction of the second transmitted light beam, the polarization direction of the second transmitted light beam is the same as the polarization direction of the first transmitted light beam, and the value interval of the angle between the polarization directions of the first reflected light beam and the first transmitted light beam is (0°, 90°).

[0084] The polarization state modulation component includes: a first polarization state converter 3411, a second polarization state converter 3412 and an optical modulator 3413. The first polarization state converter 3411 and the second polarization state converter 3412 are respectively located in the optical path of the first reflected light beam and the second reflected light beam, and are used to adjust the polarization states of the first reflected light beam and the second reflected light beam, so that the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam are the same.

[0085] In addition, in the embodiment of the present invention, the first polarization state converter 3411 may be arranged on the optical path where the first transmitted light beam is located, and the second polarization state converter 3412 may be arranged on the optical path where the second reflected light beam is located. Figure 4B As shown, Figure 4B Another structural principle diagram of the polarization modulation device for stereoscopic projection light according to the second embodiment of the present invention is shown. Figure 4B In the embodiment, the polarization direction of the first reflected light beam is orthogonal to the polarization direction of the first transmitted light beam, the polarization direction of the second transmitted light beam is the same as the polarization direction of the first reflected light beam, and the value interval of the angle between the polarization directions of the second reflected light beam and the second transmitted light beam is (0°, 90°); or, the polarization direction of the second reflected light beam is orthogonal to the polarization direction of the second transmitted light beam, the polarization direction of the second transmitted light beam is the same as the polarization direction of the first reflected light beam, and the value interval of the angle between the polarization directions of the first reflected light beam and the first transmitted light beam is (0°, 90°).

[0086] It should be understood that, in specific implementation, the positions of the first polarization state converter 3411 and the second polarization state converter 3412 have multiple variations, the above preferred embodiment only describes two of them, and the remaining situations include: respectively located in the optical path where the first reflected light beam and the second transmitted light beam are located, respectively located in the optical path where the first transmitted light beam and the second transmitted light beam are located, and respectively located in the optical path where the first transmitted light beam and the second reflected light beam are located, which will not be repeated here. In addition, the polarization state converter located on the first reflected light beam or the second reflected light beam can also be located between the polarization beam splitting component and the first optical path direction adjustment component or the second optical path direction adjustment component.

[0087] After the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam are modulated into the same polarization state, the light modulator 3413 modulates the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam, which have the same polarization state, into left-handed circularly polarized light and right-handed circularly polarized light in a frame sequence. For example, in the current frame, the light modulator 3413 adjusts each light beam into left-handed circularly polarized light, so that the left lens of the circularly polarized glasses worn by the audience can pass through the left-handed circularly polarized light, while the right lens cannot pass through the left-handed circularly polarized light; in the next frame, the light modulator 3413 adjusts each light beam into right-handed circularly polarized light, so that the right lens of the circularly polarized glasses worn by the audience can pass through the right-handed circularly polarized light, while the left lens cannot pass through the right-handed circularly polarized light. In addition, the light modulator 3413 can also modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam, which have the same polarization state, into left-handed elliptical polarized light and right-handed elliptical polarized light in a frame sequence.

[0088] As a variation of the second embodiment, the polarization beam splitting assembly can also be designed as a polarization beam splitting prism group. Figure 5 As shown, the polarization beam splitter prism group is formed by laminating at least three isosceles right-angle prisms, namely, a first prism 3121, a second prism 3122 and a third prism 3123. After laminating, the whole is in a rectangular parallelepiped structure. The three isosceles right-angle prisms are made of a transparent substrate. The two right-angled sides of the third prism 3123 are respectively laminated with the hypotenuse of the first prism 3121 and the hypotenuse of the second prism 3122. The laminating parts are provided with a first polarization beam splitter layer 3124 and a second polarization beam splitter layer 3125 respectively. The first polarization beam splitter layer 3124 and the second polarization beam splitter layer 3125 are perpendicular to each other and connected to each other in a V shape. A ridge A2 is formed at the connected position. The protruding direction of the ridge A2 is opposite to the propagation direction of the projection light beam. When the above-mentioned projection light beam is projected onto the above-mentioned polarization beam splitter prism group, the first polarization beam splitter layer 3124 can transmit a first transmission light beam and reflect a first reflection light beam, and the second polarization beam splitter layer 3125 can transmit a second transmission light beam and reflect a second reflection light beam. In the above polarization beam splitter prism set, the surface where the ridge A2 is located is the incident surface of the projection light beam. When used specifically, it is best to place the ridge A2 on the center line of the projection light beam.

[0089] The first polarization splitting layer 3124 and the second polarization splitting layer 3125 can also be composed of several layers of optical films stacked together. When the unpolarized projection light beam is incident on the optical film on the first polarization splitting layer 3124, it can be split into a transmitted first transmitted light beam with a first polarization state, and a reflected first reflected light beam with a second polarization state; when the unpolarized projection light beam is incident on the optical film on the second polarization splitting layer 3125, it can be split into a transmitted second transmitted light beam with a first polarization state, and a reflected second reflected light beam with a third polarization state.

[0090] To summarize, in the second embodiment, a projection light beam corresponding to a complete image screen is split into two reflected light beams by the polarization splitting layers on the two substrates during polarization, or is split into two reflected light beams by the two polarization splitting layers inside the prism group, thereby effectively reducing the optical path difference between the reflected light beam and the transmitted light beam, so that the subsequent optical path direction adjustment components and optical path compensation components can be of smaller size, thereby greatly reducing the size of the entire device. Moreover, compared with the oblique plate type splitter prism with dual optical paths, this "V"-shaped polarization beam splitting component can be made thinner, with the thickness reduced by almost half.

[0091] Further, based on the above embodiment, Fig. 6A The third embodiment of the present invention shows a polarization modulation device for stereoscopic projection light. The polarization beam splitting component in this embodiment is used to split the projection light beam carrying image information into a first transmitted light beam, a second transmitted light beam, a first reflected light beam and a second reflected light beam with four different polarization states. The device is also suitable for situations where the audience wears circularly polarized glasses.

[0092] In this embodiment, the polarization splitting layer on the first substrate 3111 and the second substrate 3112 in the polarization beam splitting component adopts a wire grid structure to realize polarization splitting. Specifically, refer to Fig. 7A or Figure 7B , Fig. 7A or Figure 7B is a wire grid structure on the polarization splitting layer on the first substrate 3111; Fig. 8A or Figure 8B , Fig. 8A or Figure 8B It is a wire grid structure on the polarization splitting layer on the second substrate 3112 .

[0093] It can be seen that the arrangement direction of the wire grid in the polarization splitting layer of the first substrate 3111 has a certain angle with the arrangement direction of the wire grid in the polarization splitting layer of the second substrate 3112, and the value range of the angle is (0°, 90°). In this embodiment, the angle can preferably be 45°.

[0094] exist Fig. 6AIn the figure, "①" indicates that the light beam is linearly polarized and has the first polarization state; "②" indicates that the light beam is linearly polarized and has the second polarization state; "③" indicates that the light beam is linearly polarized and has the third polarization state; "④" indicates that the light beam is linearly polarized and has the fourth polarization state; "●" indicates that the light beam is circularly polarized. The value range of the angle between the polarization direction of the first polarization state and the polarization direction of the second polarization state is (0°, 90°), the polarization direction of the third polarization state is orthogonal to the polarization direction of the first polarization state, and the polarization direction of the fourth polarization state is orthogonal to the polarization direction of the second polarization state. Specifically, the above angle may preferably be 45°.

[0095] It can be understood that, in this embodiment, the polarization splitting layers on the first substrate 3111 and the second substrate 3112 in the polarization beam splitting component can also be polarization splitting films formed by stacking several layers of optical films to achieve polarization splitting.

[0096] In an embodiment of the present invention, a polarization state modulation component includes: a first polarization state converter, a second polarization state converter, a second polarization state converter, and an optical modulator. The first polarization state converter, the second polarization state converter, and the second polarization state converter are located in the optical path where any three of the first transmitted light beam, the second transmitted light beam, the first reflected light beam, and the second reflected light beam are located, and are used to adjust the polarization states of the light beams passing through the first polarization state converter, the second polarization state converter, and the second polarization state converter, so that the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam, and the second reflected light beam are the same.

[0097] Please refer again Fig. 6A As a preferred embodiment, the first polarization state converter 3421 is located on the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam from the third polarization state to the first polarization state; the second polarization state converter 3422 is located on the optical path where the second transmitted light beam is located, and is used to convert the polarization state of the second transmitted light beam from the second polarization state to the first polarization state; the third polarization state converter 3423 is located on the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam from the fourth polarization state to the first polarization state.

[0098] In addition, if Figure 6B As stated, Figure 6BAnother structural principle diagram of the polarization modulation device of the stereoscopic projection light according to the second embodiment of the present invention is shown. In the embodiment of the present invention, the first polarization state converter 3421 can also be arranged on the optical path where the first transmitted light beam is located, for converting the polarization state of the first transmitted light beam from the first polarization state to the third polarization state, the second polarization state converter 3422 is arranged on the optical path where the second transmitted light beam is located, for converting the polarization state of the second transmitted light beam from the second polarization state to the third polarization state, and the third polarization state converter 3423 is arranged on the optical path where the second reflected light beam is located, for converting the polarization state of the second reflected light beam from the fourth polarization state to the third polarization state.

[0099] It should be understood that, in a specific implementation, there are four configurations of the first polarization state converter 3421, the second polarization state converter 3422, and the third polarization state converter 3423. The above preferred embodiment only describes two of them, and the remaining two are not described here. In addition, the polarization state converter located on the first reflected light beam or the second reflected light beam can also be located between the polarization beam splitting component and the first optical path direction adjustment component or the second optical path direction adjustment component.

[0100] After the first polarization state converter 3421, the second polarization state converter 3422 and the third polarization state converter 3423 each adjust the polarization state of their respective light beams to be consistent, the light modulator 3424 modulates the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam, which all have the first polarization state or the third polarization state, into left-handed circularly polarized light and right-handed circularly polarized light in a frame sequence. For example, in the current frame, the light modulator 3424 adjusts each light beam to be left-handed circularly polarized light, so that the left lens of the circular polarized glasses worn by the audience can transmit the left-handed circularly polarized light, while the right lens cannot transmit the left-handed circularly polarized light; in the next frame, the light modulator 3424 adjusts each light beam to be right-handed circularly polarized light, so that the right lens of the circular polarized glasses worn by the audience can transmit the right-handed circularly polarized light, while the left lens cannot transmit the right-handed circularly polarized light. In addition, the above-mentioned light modulator 3424 can also modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam with the same polarization state into left-handed elliptically polarized light and right-handed elliptically polarized light in a frame sequence.

[0101] As a variation of the third embodiment, the polarization beam splitting assembly can also be designed as a polarization beam splitting prism group. Fig. 9As shown, the polarization beam splitter prism group is formed by laminating at least three isosceles right-angle prisms, namely, a first prism 3131, a second prism 3132 and a third prism 3133. After laminating, the whole is in a rectangular parallelepiped structure. The three isosceles right-angle prisms are made of a transparent substrate. The two right-angle sides of the third prism 3133 are respectively laminated with the hypotenuse of the first prism 3131 and the hypotenuse of the second prism 3132. The laminating parts are provided with a first polarization beam splitter layer 3134 and a second polarization beam splitter layer 3135 respectively. The first polarization beam splitter layer 3134 and the second polarization beam splitter layer 3135 are perpendicular to each other and connected to each other in a V shape. A ridge A3 is formed at the connected position. The protruding direction of the ridge A3 is opposite to the propagation direction of the projection light beam. When the above-mentioned projection light beam is projected onto the above-mentioned polarization beam splitter prism group, the first polarization beam splitter layer 3134 can transmit a first transmission light beam and reflect a first reflection light beam, and the second polarization beam splitter layer 3135 can transmit a second transmission light beam and reflect a second reflection light beam. In the above polarization beam splitter prism set, the surface where the ridge A3 is located is the incident surface of the projection light beam. When used specifically, it is best to place the ridge A3 on the center line of the projection light beam.

[0102] Among them, the first polarization splitting layer 3134 and the second polarization splitting layer 3135 can also adopt a wire grid structure. When the unpolarized projection light beam is incident on the wire grid structure on the first polarization splitting layer 3134, it can be split into a transmitted first transmitted light beam with a first polarization state, and a reflected first reflected light beam with a third polarization state; when the unpolarized projection light beam is incident on the wire grid structure on the second polarization splitting layer 3135, it can be split into a transmitted second transmitted light beam with a second polarization state, and a reflected second reflected light beam with a fourth polarization state.

[0103] As for the polarization splitting layer on the polarization beam splitting component using a prism group structure, Fig. 10A and Fig. 10B The wire grid structure on the first polarization splitting layer 3124 and the wire grid structure on the second polarization splitting layer 3125 are shown respectively. It can be seen that Fig. 10A When the wire grids are arranged in the vertical direction, when the unpolarized projection beam R Randomly When incident on the wire grid structure on the first polarization splitting layer 3124, it can be split into a transmitted first transmitted light beam R1 with a first polarization state and a reflected first reflected light beam R2 with a third polarization state; and Fig. 10B When the unpolarized projection beam R Randomly When incident on the wire grid structure on the second polarization splitting layer 3125 , it can be split into a transmitted second transmitted light beam R3 with a second polarization state and a reflected second reflected light beam R4 with a fourth polarization state.

[0104] It can be understood that, in this embodiment, the first polarization splitting layer 3134 and the second polarization splitting layer 3135 in the above prism group structure can also adopt polarization splitting films formed by stacking several layers of optical films to achieve polarization splitting.

[0105] To summarize, in the third embodiment of the present invention, a projection light beam corresponding to a complete image screen is split into two reflected light beams by the polarization splitting layers on the two substrates during polarization, or is split into two reflected light beams by the two polarization splitting layers inside the prism group, thereby effectively reducing the optical path difference between the reflected light beam and the transmitted light beam, so that the subsequent optical path direction adjustment components and optical path compensation components can be of smaller size, thereby greatly reducing the size of the entire device. Moreover, compared with the oblique plate type splitter prism with dual optical paths, this "V"-shaped polarization beam splitting component can be made thinner, with the thickness reduced by almost half.

[0106] Furthermore, considering that in the third embodiment, the projection light beam is not strictly divided into two non-intersecting parts when passing through the polarization beam splitter, in fact, part of the light beam passing through the upper part of the polarization beam splitter will propagate downward, and conversely, part of the light beam passing through the lower part of the polarization beam splitter will propagate upward, so in the central area of ​​the imaging surface, the two polarization states of the light beam are actually mixed together, such as Fig.11 As shown, the "dotted line" represents the upper half of the projection beam, and the "long and short lines" represent the lower half of the projection beam. It can be seen that after passing through the polarization beam splitter, the upper and lower parts of the projection beam will have a mixed area. When there are two polarization states of transmitted light in the mixed area, the subsequent polarization state modulation component will have certain difficulties in adjusting the polarization state consistency of the projection beam in the mixed area. To solve this technical problem, the fourth embodiment of the present invention provides a polarization modulation device for stereoscopic projection light, which is suitable for the situation where the audience wears circular polarized glasses.

[0107] See also Fig. 12A and Fig. 12B , which is different from the third embodiment, in this embodiment, the second polarization state converter 3422 is placed at a position where Fig. 12A In the embodiment, the first polarization state converter 3421 is located in the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam into a first target polarization state. The second polarization state converter 3422 is attached to the first polarization beam splitting layer in the polarization beam splitting component, and is located on the side of the first polarization beam splitting layer that can transmit the first transmitted light beam, and is used to convert the polarization state of the first transmitted light beam into a first target polarization state. The third polarization state converter 3423 is located in the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam into a first target polarization state. The first target polarization state is the same as the polarization state of the second transmitted light beam.

[0108] Fig. 12B In the figure, the first polarization state converter 3421 is located in the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam into a second target polarization state. The second polarization state converter 3422 is attached to the second polarization splitting layer in the polarization beam splitting component and is located on the side of the second polarization splitting layer that can transmit the second transmitted light beam, and is used to convert the polarization state of the second transmitted light beam into a second target polarization state. The third polarization state converter 3423 is located in the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam into a second target polarization state. The above-mentioned second target polarization state is the same as the polarization state of the first transmitted light beam.

[0109] In the above manner, the polarization state of the second transmitted light beam is converted before the second transmitted light beam is mixed with the first transmitted light beam. Fig.11 The polarization states of the light beams in the mixing region shown in FIG. 1 are already consistent.

[0110] For the polarization beam splitting component in the form of a prism structure shown in the third embodiment, the second polarization state converter 3422 can be packaged in the polarization beam splitting prism group and located on the side where the second polarization beam splitting layer 3135 can transmit the second transmission light beam, such as Fig.13 Of course, the first polarization state converter 3421 can also be packaged on the side of the first polarization splitting layer 3134 that can transmit the first transmission light beam.

[0111] The rest of the fourth embodiment is the same as the third embodiment and will not be described again.

[0112] It can be understood that when the polarization states of the first transmitted light beam and the second transmitted light beam in the second embodiment of the present invention are different, the method described in the fourth embodiment of the present invention can also be adopted to attach the polarization state converter to the side of the first polarization splitting layer in the polarization beam splitting component that can transmit the first transmitted light beam; or, attach the polarization state converter to the side of the second polarization splitting layer in the polarization beam splitting component that can transmit the second transmitted light beam.

[0113] To sum up, in the fourth embodiment, a projection light beam corresponding to a complete image screen is not only divided into two reflected light beams by the polarization splitting layers on the two substrates or by the two polarization splitting layers inside the prism group during polarization, but also the polarization state of the second transmitted light beam is converted before the second transmitted light beam is mixed with the first transmitted light beam. Therefore, while effectively reducing the optical path difference between the reflected light beam and the transmitted light beam and greatly reducing the volume of the entire device, it is also more conducive to the subsequent polarization light modulation component to modulate the polarization state of the two transmitted light beams. Similarly, the "V"-shaped polarization beam splitting component in this embodiment can be made thinner than the oblique plate type splitter prism with a dual light path, with the thickness reduced by almost half.

[0114] The fifth embodiment of the present invention further provides a stereoscopic image projection system, comprising a projector, a polarization modulation device and a screen. The projector is used to sequentially project a projection light beam carrying left-eye image information and a projection light beam carrying right-eye image information in frame order; the polarization modulation device can be the polarization modulation device provided in any of the above embodiments; and the screen is used as an imaging surface for imaging each projection light beam with the same polarization state modulated by the polarization modulation device of the stereoscopic projection light, and reflects the formed image to the 3D glasses worn by the user.

[0115] The sixth embodiment of the present invention further provides a polarization modulation method for stereoscopic projection light, the method comprising the following steps:

[0116] In step S1 , a projection beam carrying image information is split into a first transmission beam, a second transmission beam, a first reflection beam and a second reflection beam having four different polarization states or three different polarization states.

[0117] Step S2, adjusting the propagation directions of the first reflected light beam and the second reflected light beam so that the first reflected light beam and the second reflected light beam propagate in the direction where the imaging surface is located.

[0118] Step S3, modulating the polarization state of part or all of the first transmitted beam, the second transmitted beam, the first reflected beam and the second reflected beam in frame sequence, so that the first transmitted beam, the second transmitted beam, the first reflected beam and the second reflected beam have the same polarization state.

[0119] For the specific implementation principles of the above steps, please refer to the contents disclosed above and will not be repeated here.

[0120] It should be noted that when the above-mentioned embodiments are implemented, different functional components can be added to achieve corresponding effects. For example, a polarization device for filtering can be set in the optical path of each light beam to make the polarization state of each light beam purer. An optical path compensation component can also be set in the optical path of some light beams to make the optical path of all light beams the same when they reach the imaging surface.

[0121] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polarization modulation device for stereoscopic projection light, characterized in that: The device comprises: A polarization beam splitting component, used for splitting a projection beam carrying image information into a first transmitted beam and a second transmitted beam having a first polarization state, a first reflected beam having a second polarization state, and a second reflected beam having a third polarization state, wherein the polarization directions of the first polarization state, the second polarization state, and the third polarization state are different from each other; The polarization beam splitting component includes two substrates, the two substrates are connected to each other in a V shape, and the protrusion direction of the ridge formed by the connection is opposite to the propagation direction of the projection light beam; the two substrates are provided with a first polarization beam splitting layer and a second polarization beam splitting layer, when the projection light beam is projected onto the two substrates, the first polarization beam splitting layer can transmit the first transmission light beam and reflect the first reflection light beam, and the second polarization beam splitting layer can transmit the second transmission light beam and reflect the second reflection light beam; Alternatively, the polarization beam splitting component is a polarization beam splitting prism group; the polarization beam splitting prism group is formed by laminating at least three prisms, and a first polarization beam splitting layer and a second polarization beam splitting layer are formed at the laminating portion; the first polarization beam splitting layer and the second polarization beam splitting layer are connected to each other in a V shape, and a ridge formed by the connection is protruding in a direction opposite to a propagation direction of the projection light beam; when the projection light beam is projected onto the polarization beam splitting prism group, the first polarization beam splitting layer can transmit the first transmitted light beam and reflect the first reflected light beam, and the second polarization beam splitting layer can transmit the second transmitted light beam and reflect the second reflected light beam; A polarization state modulation component, the polarization state modulation component comprising a first polarization state converter, a second polarization state converter, a third polarization state converter and an optical modulator; The first polarization state converter, the second polarization state converter and the third polarization state converter are located in the optical path of any three of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam, and are used to adjust the polarization states of the light beams passing through the first polarization state converter, the second polarization state converter and the third polarization state converter so that the polarization states of the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam are the same; The first polarization state converter is located in the optical path where the first reflected light beam is located, and is used to convert the polarization state of the first reflected light beam into a second target polarization state. The second polarization state converter is attached to the second polarization beam splitting layer in the polarization beam splitting component and is located on the side of the second polarization beam splitting layer that can transmit the second transmitted light beam, and is used to convert the polarization state of the second transmitted light beam into the second target polarization state. The third polarization state converter is located in the optical path where the second reflected light beam is located, and is used to convert the polarization state of the second reflected light beam into the second target polarization state, and the second target polarization state is the same as the polarization state of the first transmitted light beam. The optical modulator is used to modulate the first transmitted light beam, the second transmitted light beam, the first reflected light beam and the second reflected light beam having the same polarization state into left-handed circularly polarized light and right-handed circularly polarized light in a frame sequence; A first optical path direction adjustment component, used for adjusting a propagation direction of the first reflected light beam so that the first reflected light beam propagates in a direction where an imaging surface is located; The second optical path direction adjustment component is used to adjust the propagation direction of the second reflected light beam so that the second reflected light beam propagates in the direction where the imaging surface is located.

2. The device according to claim 1, characterized in that The angle between the wire grid arrangement direction of the first polarization splitting layer and the wire grid arrangement direction of the second polarization splitting layer is 45°; the angle between the polarization direction of the first transmitted light beam and the polarization direction of the second transmitted light beam is 45°.

3. A stereoscopic image projection system, characterized in that: The system comprises: A projector, used to sequentially project a projection light beam carrying left-eye image information and a projection light beam carrying right-eye image information in a frame sequence; A polarization modulation device, wherein the polarization modulation device is the polarization modulation device for stereoscopic projection light according to any one of claims 1 to 2; The screen is used for imaging each projection light beam with the same polarization state modulated by the polarization modulation device of the stereoscopic projection light, and reflecting the formed image to the 3D glasses worn by the user.

Images