Projection display system and near-to-eye display equipment

Abstract

The invention discloses a projection display system and near-to-eye display equipment. The projection display system comprises a beam splitter prism, a display element and an imaging assembly. The beam splitter prism is matched with a reflector, a field lens and a single lens in the imaging assembly, and light in the projection display system is turned. Light emitted by the display element enters the beam splitter prism after passing through the field lens and is transmitted to the reflector by the beam splitter prism, the reflector reflects the light, and the reflected light enters the beam splitter prism again, is reflected to the single lens by the beam splitter prism and then is emitted from the light emitting side of the projection display system. Therefore, the imaging light path is compressed, the size of the projection display system is effectively reduced, and the miniaturization of the projection display system is realized.

Description

Technical Field

[0001] The present application relates to the field of augmented reality lens optical design, and in particular to a projection display system and a near-eye display device. Background Art

[0002] With the continuous development of augmented reality (AR) technology, near-eye display products have been gradually widely used in civil fields such as film and television, education, and medical care, rather than initially being used in the military field.

[0003] Currently, near-eye display optical systems generally feature high brightness, a wide field of view, high contrast, and high resolution, providing users with an immersive visual experience. However, the large size of optical modules remains a prominent issue in the design of AR optical architectures. This directly results in the smallest form factor of current AR display devices remaining similar in size to sunglasses, making it difficult to achieve a thin and lightweight form factor comparable to ordinary myopic glasses. Summary of the Invention

[0004] According to a first aspect of an embodiment of the present application, a projection display system is provided, comprising:

[0005] A display component for displaying images;

[0006] A beam splitter prism is located on the light-emitting side of the display element; the beam splitter prism comprises: a first surface, a second surface, and a light-emitting surface; wherein the first surface and the second surface are arranged opposite to each other, and the light-emitting surface is connected to one end of the first surface and one end of the second surface respectively; and

[0007] Imaging assembly; the imaging assembly includes: a reflector, a field lens and a single lens;

[0008] The display element is arranged facing the first surface; the reflective surface of the reflector is arranged facing the second surface; the field lens is located between the display element and the first surface of the beam splitter prism; and the single lens is located on the light-emitting surface side of the beam splitter prism.

[0009] The light emitted by the display element is incident on the dichroic prism, and is transmitted by the dichroic prism to the reflector. The reflector reflects the light, and the reflected light is incident on the dichroic prism again and is reflected by the dichroic prism toward the light output side of the projection display system.

[0010] In some embodiments, the beam splitter prism comprises: two mutually aligned triangular prisms and a polarization splitting layer located on the aligned surfaces of the two triangular prisms; the polarization splitting layer is configured to transmit a first linearly polarized light and reflect a second linearly polarized light; the polarization direction of the first linearly polarized light is parallel to the incident plane of the incident light, and the polarization direction of the second linearly polarized light is perpendicular to the incident plane of the incident light. In some embodiments, the reflector is a convex lens, with a reflective film disposed on the surface of the convex lens facing away from the beam splitter prism; the surface of the reflector facing the beam splitter prism is a curved or flat surface;

[0011] The field lens is a cemented lens; the surface of the field lens close to the beam splitter prism is a curved surface or a flat surface;

[0012] The single lens is an aspherical lens; the effective focal length of the surface of the single lens away from the dichroic prism is smaller than the effective focal length of the surface of the single lens close to the dichroic prism; the surface of the single lens close to the dichroic prism is a curved surface or a flat surface.

[0013] In some embodiments, the imaging assembly further comprises:

[0014] an aperture, located on a side of the single lens facing away from the beam splitter prism;

[0015] a phase compensator, located on the light-emitting side of the display element; the phase compensator is used to convert all the light emitted by the display element into the first linearly polarized light;

[0016] a first phase retarder, located between the reflector and the beam splitter; the first phase retarder is used to convert the incident first linearly polarized light or the second linearly polarized light into circularly polarized light; and

[0017] The second phase retarder is located between the beam splitter prism and the single lens; the second phase retarder is used to change the polarization direction of the incident light.

[0018] In some embodiments, the display element comprises:

[0019] a display screen for displaying images; and

[0020] a protective glass located on the light-emitting side of the display screen;

[0021] Alternatively, the display element comprises:

[0022] a display screen for displaying images; and

[0023] A light field modulation element is located on the light-emitting side of the display screen; the light field modulation element is used to perform light field modulation on the light emitted from the display screen to achieve three-dimensional display.

[0024] In some embodiments, the light field modulation element is a microlens array or a cylindrical lens array.

[0025] In some embodiments, the display screen is a liquid crystal display screen, an organic light emitting diode display screen, or a micro light emitting diode display screen.

[0026] In some embodiments, the display screen is a liquid crystal on silicon display screen;

[0027] The beam splitter prism further comprises: a light incident surface; the light incident surface and the light emitting surface are arranged opposite to each other;

[0028] The projection display system further comprises:

[0029] A light source assembly is located on one side of the light incident surface of the beam splitter prism; the light source assembly is used to provide lighting for the display element.

[0030] In some embodiments, the light source assembly includes:

[0031] a light source, located on one side of the light incident surface of the beam splitter prism;

[0032] A shaping component is located between the light source and the beam splitter prism; the shaping component is used to shape and homogenize the output light of the light source;

[0033] a polarizer, located between the shaping component and the beam splitter prism; a transmission axis of the polarizer is parallel to the polarization direction of the second linearly polarized light;

[0034] The light source assembly also shares the field lens in the imaging assembly.

[0035] In some embodiments, the shaping component comprises:

[0036] a collimating lens group, located on the light-emitting side of the light source; the collimating lens group includes at least one lens, and the lens is an aspheric lens;

[0037] a fly-eye lens, located on a side of the collimating lens group away from the light source;

[0038] a relay lens, located on a side of the fly-eye lens away from the collimating lens group;

[0039] The light homogenizing element is located between the relay lens and the polarizer; the light homogenizing element is a diffuser.

[0040] In some embodiments, the effective focal length of the projection display system is 5.0 mm to 9.5 mm.

[0041] In some embodiments, the projection display system has a field of view of 20° to 55°;

[0042] The exit pupil diameter of the projection display system is 2.5 mm to 4 mm.

[0043] According to a second aspect of an embodiment of the present application, a near-eye display device is provided, comprising:

[0044] A projection display system, wherein the projection display system is the projection display system according to any one of claims 1 to 12;

[0045] The optical waveguide component is located on the light-emitting side of the projection display system; the optical waveguide component is used to receive the light emitted by the projection display system, conduct it, expand the pupil in two dimensions, and emit it towards the human eye.

[0046] In some embodiments, the optical waveguide assembly comprises:

[0047] optical waveguides;

[0048] A coupling-in grating is located on the optical waveguide; the coupling-in grating is used to receive the light emitted by the projection display system and couple it into the optical waveguide;

[0049] a turning grating located on the optical waveguide; the turning grating is used to expand the pupil of the light emitted by the projection display system along a first direction;

[0050] an outcoupling grating located on the optical waveguide; the outcoupling grating is used to expand the pupil of the light after the pupil is expanded along the first direction along a second direction, and couple the light out of the optical waveguide toward the human eye; the first direction and the second direction are perpendicular;

[0051] The sum of the grating vector of the coupling-in grating, the grating vector of the turning grating, and the grating vector of the coupling-out grating is 0.

[0052] In some embodiments, the field of view of the optical waveguide assembly is greater than or equal to the field of view of the projection display system;

[0053] The size of the coupling-in grating is larger than the exit pupil diameter of the projection display system; the size of the coupling-in grating is 2.7 mm to 4.2 mm.

[0054] The present application provides a projection display system and a near-eye display device, wherein the projection display system includes a dichroic prism, a display element, and an imaging assembly. The dichroic prism and the reflector, field lens, and single lens in the imaging assembly cooperate with each other to deflect the light in the projection display system. The light emitted by the display element passes through the field lens and is incident on the dichroic prism. The light is transmitted by the dichroic prism to the reflector, which reflects the light. The reflected light is incident on the dichroic prism again, reflected by the dichroic prism to the single lens, and then emitted from the light-emitting side of the projection display system. In this way, the imaging optical path is compressed, the volume of the projection display system is effectively reduced, and the miniaturization of the projection display system is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings introduced below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 This is one of the structural diagrams of the projection display system provided in an embodiment of the present application;

[0057] Figure 2 One of the structural schematic diagrams of the display element provided in the embodiment of the present application;

[0058] Figure 3 The second structural diagram of the display element provided in the embodiment of the present application;

[0059] Figure 4 This is a second structural diagram of the projection display system provided in an embodiment of the present application;

[0060] Figure 5 This is a schematic diagram of the illumination uniformity of the central field of view of the display screen surface provided in an embodiment of the present application;

[0061] Figure 6 The second schematic diagram of the illumination uniformity of the central field of view of the display screen surface provided in an embodiment of the present application;

[0062] Figure 7 This is a third structural diagram of the projection display system provided in an embodiment of the present application;

[0063] Figure 8 One of the modulation transfer function curves of the projection display system provided in an embodiment of the present application;

[0064] Figure 9 One of the standard mobile imaging architecture television distortion diagrams of the projection display system provided in an embodiment of the present application;

[0065] Figure 10 One of the vertical axis chromatic aberration diagrams of the projection display system provided in an embodiment of the present application;

[0066] Figure 11 One of the relative illumination diagrams of the projection display system provided in an embodiment of the present application;

[0067] Figure 12 This is a fourth structural diagram of the projection display system provided in an embodiment of the present application;

[0068] Figure 13 The second modulation transfer function curve diagram of the projection display system provided in an embodiment of the present application;

[0069] Figure 14 The second diagram of the standard mobile imaging architecture television distortion of the projection display system provided in the embodiment of the present application;

[0070] Figure 15 The second vertical axis chromatic aberration diagram of the projection display system provided in an embodiment of the present application;

[0071] Figure 16 A schematic structural diagram of an optical waveguide assembly for a near-eye display device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0072] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application will be further described below with reference to the accompanying drawings and examples. However, the example embodiments can be implemented in various forms and should not be understood as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and their repeated descriptions will be omitted. The words expressing position and direction described in this application are all explained using the accompanying drawings as examples, but changes can be made as needed, and all changes are included in the scope of protection of this application. The drawings in this application are only used to illustrate relative position relationships and do not represent true proportions.

[0073] Near-eye displays (NEDs) are devices worn on the user's eyes, typically in the form of glasses or helmets, and can provide users with virtual reality (VR) and augmented reality (AR) experiences. AR NED technology uses an optical transmission scheme to fuse virtual images generated by the NED with real-world scenes, ultimately providing users with an enhanced view of the real world. VR NED technology displays images for each eye separately on their respective NEDs. The left and right eyes receive different image information, which is then synthesized into stereoscopic vision in the brain.

[0074] However, while near-eye display devices offer an immersive visual experience, their large size also presents significant technical challenges. The issue of excessive optical module size remains prominent in optical architecture design, directly resulting in the current smallest form factor of near-eye display devices remaining roughly the size of sunglasses, making it difficult to achieve a thin and lightweight form factor comparable to ordinary myopia glasses.

[0075] In view of this, an embodiment of the present application provides a projection display system that can effectively reduce the volume of the projection display system, thereby reducing the space occupied by the projection display system in a near-eye display device and realizing the miniaturization of the near-eye display device.

[0076] Figure 1 This is a schematic diagram of the structure of the projection display system provided in an embodiment of the present application.

[0077] like Figure 1 As shown, a projection display system provided by an embodiment of the present application includes: a display element 11 , a beam splitter prism 12 , and an imaging component 13 .

[0078] The imaging component 13 includes a plurality of lenses, and the plurality of lenses includes a reflector 131 .

[0079] The reflector 131 in the embodiment of the present application is located on the side of the dichroic prism 12 away from the display element 11. The light emitted by the display element 11 is incident on the dichroic prism 12, and is transmitted by the dichroic prism 12 to the reflector 131. The reflector 131 reflects the light, and the reflected light is incident on the dichroic prism 12 again, and is reflected by the dichroic prism 12 toward the light-emitting side of the projection display system. The embodiment of the present application uses the dichroic prism 12 and the reflector 131 structure to achieve a light path turning in the projection display system. The projection display system can replace the optical system structure of the Birdbath solution and the free-form surface solution of the related technologies. The volume of the optical system of the related technology solutions is at least greater than 6 cubic centimeters. The volume of the projection display system of the present application is less than 1.2 cubic centimeters. The volume of the projection display system is reduced, and the miniaturization of the projection display system can be achieved.

[0080] In some embodiments, as Figure 1 As shown, the spectroscopic prism 12 is composed of two mutually opposed triangular prisms 121 and 122, and a polarization splitting layer 123 located on the opposing surfaces of the two triangular prisms. The polarization splitting layer 123 can transmit polarized light with a polarization direction parallel to the incident plane of the incident light, that is, p-polarized light, which is referred to as the first linear polarized light in the embodiment of the present application; the polarization splitting film can reflect polarized light with a polarization direction perpendicular to the incident plane of the incident light, that is, s-polarized light, which is referred to as the second linear polarized light in the embodiment of the present application.

[0081] The beam splitter prism 12 includes a first surface 124, a second surface 125, a light-emitting surface 126, and a light-incident surface 127; wherein the first surface 124 and the second surface 125 are arranged opposite to each other, the light-incident surface 127 and the light-emitting surface 126 are arranged opposite to each other, the light-emitting surface 126 is respectively connected to one end of the first surface 124 and the second surface 125, and the light-incident surface 127 is respectively connected to the other end of the first surface 124 and the second surface 125.

[0082] The display element 11 is disposed facing the first surface 124, and the reflective surface of the reflector 131 is disposed facing the second surface 125. The beam splitter prism 12 can deflect light and complete the transmission of light between the imaging component 13, and emit the light from the light-emitting side of the projection display system, thereby reducing the volume of the projection display system and achieving miniaturization of the projection display system.

[0083] In some embodiments, the reflector 131 is a convex lens having a reflective film on the surface facing away from the beam splitter prism 12 for reflecting light. The effective focal length of the reflector 131 is 7.5 mm to 10 mm, and the surface of the reflector 131 facing the beam splitter prism 12 can be curved or flat. The curved surface of the reflector 131 facing the beam splitter prism 12 provides more optical design freedom for the projection display system and improves the imaging quality of the projection display system. The flat surface of the reflector 131 facing the beam splitter prism 12 allows the reflector 131 to mate with the second surface of the beam splitter prism 12, thereby improving the integration of the projection display system.

[0084] In some embodiments, as Figure 1 As shown, the multiple lenses also include a field lens 132 and a single lens 133. The field lens 132 is located between the display element 11 and the first surface of the beam splitter prism 12. The field lens 132 can be two spherical glass lenses with different refractive indices glued together. The effective focal length range of the field lens 132 is 20 mm to 30 mm. The field lens 132 can be made of high-refractive-index glass material. The refractive index of the spherical glass lens on the side close to the beam splitter prism 12 can be greater than 1.6, and the refractive index of the spherical glass lens on the side close to the display element 11 can be greater than 1.79. The field lens 132 is made of high-refractive-index glass material, which can produce a larger turning angle for the light and quickly converge the light onto the beam splitter prism 12, thereby reducing the size of the beam splitter prism 12 and giving the projection display system the advantage of miniaturization. In addition, the field lens 132 uses two lenses with different refractive indices glued together to reduce chromatic aberration, thereby improving the imaging quality of the projection display system.

[0085] The surface of the field lens 132 close to the beam splitter prism 12 can be a curved surface or a flat surface. The surface of the field lens 132 close to the beam splitter prism 12 is a curved surface, which provides more optical design freedom for the projection display system, can reduce the chromatic aberration of the projection display system, and improve the imaging quality; the surface of the field lens 132 close to the beam splitter prism 12 is a flat surface, which can be fitted with the surface of the beam splitter prism 12, which is beneficial to reducing the loss of imaging quality caused by component assembly, helps to improve the yield, and makes the structure of the projection display system more compact, reducing the volume of the projection display system.

[0086] The single lens 133 is located on the light-emitting surface side of the beam splitter prism 12. The single lens 133 can be an aspheric lens. The material of the single lens 133 is a low-stress material, which can reduce the impact on the polarization state of the output light of the projection display system, reduce aberrations, and improve imaging quality. The effective focal length of the single lens 133 is 30mm to 45mm, the effective focal length of the surface of the single lens 133 on the side away from the beam splitter prism 12 is -145mm to 50mm, and the effective focal length of the surface of the single lens 133 on the side close to the beam splitter prism 12 is 25mm to 260mm. The effective focal length of the surface of the single lens 133 on the side away from the beam splitter prism 12 is smaller than the effective focal length of the surface of the single lens 133 on the side close to the beam splitter prism 12, which is conducive to reducing the volume of the beam splitter prism 12, thereby realizing the miniaturization of the projection display system.

[0087] The surface of the single lens 133 close to the dichroic prism 12 can be a curved surface or a flat surface. When the surface of the single lens 133 close to the dichroic prism 12 is a curved surface, it provides more optical design freedom for the projection display system, thereby reducing the aberration of the projection display system and improving the imaging quality; when the surface of the single lens 133 close to the dichroic prism 12 is a flat surface, it can fit with the surface of the dichroic prism 12, which is beneficial to reduce the loss of imaging quality caused by component assembly, helps to improve the yield, and makes the structure of the projection display system more compact, reducing the volume of the projection display system.

[0088] In some embodiments, as Figure 1 As shown, the imaging assembly further includes a phase compensation plate 134 , a first phase delay plate 135 , a second phase delay plate 136 and an aperture 137 .

[0089] The phase compensator 134 is located on the light-emitting side of the display element 11. The phase compensator 134 is a thin film element with a fixed phase delay function or a component in which the thin film is clamped by glass sheets. It converts the output light of the display element into the first linearly polarized light, ensuring that all the light output from the display element 11 can be transmitted through the dichroic prism 12, thereby improving the light efficiency.

[0090] A first phase retarder 135 is located between the reflector 131 and the beam splitter 12. The first phase retarder 135 is used to convert the incident first linearly polarized light or second linearly polarized light into circularly polarized light. A second phase retarder 136 is located between the beam splitter 12 and the single lens 133. The second phase retarder 136 is used to change the polarization direction of the incident light.

[0091] In a specific implementation, the first phase retarder 135 can be a λ / 4 wave plate. The first linearly polarized light emitted by the display element passes through the beam splitter prism 12 and is incident on the first phase retarder 135, where it is converted into right-handed circularly polarized light. The right-handed circularly polarized light is then incident on the reflector 131, where it is reflected and converted into left-handed circularly polarized light. The left-handed circularly polarized light is then incident on the first phase retarder 135 again and converted into second linearly polarized light. The second linearly polarized light is then incident on the beam splitter prism 12 again and reflected by the beam splitter prism 12 toward the second phase retarder 136.

[0092] In a specific implementation, the second phase retarder 136 may be a half-wave plate, which is used to change the polarization direction of light to adapt to the subsequent light path.

[0093] The light emitted by the display element 11 is deflected and emitted in the projection display system, which can reduce the volume of the projection display system and realize miniaturization of the projection display system.

[0094] The aperture 137 is located on a side of the single lens 133 away from the dichroic prism. The aperture 137 can limit the range of the outgoing light, thereby limiting the aperture angle of the projection display system and improving the imaging effect of the projection display system.

[0095] In some embodiments, as Figure 2 As shown, the display element 11 includes: a display screen 112 and a protective glass 111; or Figure 3 As shown, the display element 11 includes a display screen 112 and a light field modulation element 113 .

[0096] The display screen 112 is used to display images. The protective glass 111 or the light field modulation element 113 is located on the light-emitting side of the display screen 112 .

[0097] Light field modulator 113 can be any element capable of modulating the spatial distribution of light, such as a single-layer microlens array, a single-layer lenticular lens array, or a metasurface array. Light field modulator 113 is used to modulate the light field emitted by display screen 112. After passing through imaging assembly 13 and beam splitter prism 12, high-resolution three-dimensional display is achieved, thereby resolving the issue of convergence conflict in human vision.

[0098] In some embodiments, the display screen 112 is a liquid crystal display (LCD), an organic light-emitting diode (OLED) display screen, or a micro light-emitting diode (Micro LED) display screen. These displays can provide light with image information for the projection display system without the need for an additional lighting light path, thereby simplifying the system structure and reducing the size of the projection display system.

[0099] In some embodiments, the display screen 112 is a liquid crystal on silicon display screen, which has a higher resolution but needs to be used with a light source. Figure 4 As shown, the projection display system further includes a light source assembly 2, which is located on one side of the light incident surface of the beam splitter prism 12 and can provide illumination for the display element 11. Light emitted by the light source is incident on the beam splitter prism 12, reflected by the beam splitter prism 12 to the display element 11, and then modulated by the display element 11 before being reflected back to the beam splitter prism 12. The light is then transmitted by the beam splitter prism 12 to the reflector 131, which reflects the light. The reflected light is then incident on the beam splitter prism 12 again and reflected by the beam splitter prism 12 toward the light exit side of the projection display system.

[0100] In some embodiments, the light source assembly 2 includes: a light source 22 , a shaping assembly 23 , a polarizer 21 , and a field lens 132 in a common imaging assembly 13 .

[0101] The light source 22 is located on one side of the light incident surface of the beam splitter prism 12 and provides illumination for the display element 11 .

[0102] The shaping component 23 is located between the light source 22 and the beam splitter prism 12 . The shaping component 23 is used to shape and homogenize the light emitted from the light source 22 , thereby improving the imaging quality of the projection display system.

[0103] Polarizer 21 is positioned between shaping assembly 23 and beam splitter prism 12. The transmission axis of polarizer 21 is parallel to the polarization direction of the second linearly polarized light. Light from light source 22 passes through polarizer 21, allowing only the second linearly polarized light to pass through it. When the second linearly polarized light enters beam splitter prism 12, it is reflected by the prism onto the surface of display element 11, thereby redirecting the light path.

[0104] In some embodiments, the shaping assembly 23 includes: a collimating lens group 234 , a fly-eye lens 233 , a relay lens 232 and a light homogenizing element 231 .

[0105] The collimating lens group 234 is located on the light-emitting side of the light source 22. The collimating lens group 234 includes at least one lens. When the collimating lens group includes only one lens, the lens can be an aspherical lens, which can collimate the light source to the maximum extent and improve the imaging quality of the projection display system.

[0106] The fly-eye lens 233 is located on the side of the collimating lens group 234 away from the light source 22. The fly-eye lens 233 is a plastic double-sided microlens array that can evenly distribute the brightness of the light source and shape the light spot, thereby improving the imaging quality of the projection display system.

[0107] The relay lens 232 is located on the side of the fly-eye lens facing away from the collimating lens assembly. It is a plastic spherical lens or an aspherical lens. The relay lens 232 is a plastic spherical lens that can adjust the assembly and coordination of the light source assembly 2, imaging assembly 13, and beam splitter prism 14, thereby improving the mass production yield rate. The relay lens 232 is an aspherical lens that increases the freedom of optical design and thus improves the light modulation capability. Aspherical lenses are more tolerant to assembly errors, helping to improve the module assembly yield rate of the imaging assembly 13, light source assembly 2, and beam splitter prism 14.

[0108] The light homogenizing element 231 is located between the relay lens 232 and the polarizer 21. The light homogenizing element 231 can be a diffuser. The light homogenizing element 231 can even out the light, adjust the light divergence angle, and interfere with the imaging of the fly-eye lens 233 near the exit pupil of the projection display system, thereby improving the imaging quality of the projection display system.

[0109] When the light field modulator 113 is used in the display element 11, it is also included in the illumination optical path of the light source assembly 2. Therefore, the design of the light source assembly 2 must take into account the converging effect of the light field modulator 113 on the light from the light source 22. By optimizing the specific parameters of the fly-eye lens 233 and the relay lens 232, the light from the light source 22 can be evenly illuminated on the surface of the display screen 112 after passing through the light field modulator 113. Furthermore, the introduction of the light field modulator 113 in the light source assembly 2 also reduces the optical power of the relay lens 232, which helps reduce the sensitivity of component processing and assembly, thereby improving the yield rate of mass production.

[0110] The projection display system including the light field modulation element 113 adopts an end-to-end design approach. Specifically, the imaging system, illumination system, and light field information processing algorithm are optimized as a whole, with image quality as the evaluation criterion. This effectively avoids limiting the upper limit of final imaging performance by using intermediate process indicators as evaluation criteria, thereby achieving optimal imaging quality for the projection display system. The light field modulation element 113 is coated with an antireflection coating, which replaces the protective glass 111 in protecting the display screen 112 surface. Furthermore, optimization of the fly-eye lens 233 and relay lens 232 optimizes illumination uniformity. Figure 5 The illumination uniformity of the central field of view on the surface of the display screen 112 is obtained when the light source assembly 2 includes the light field modulation element 113 and the light source assembly 2 is not additionally optimized. Figure 6 When the light source assembly 2 includes the light field modulation element 113 and the light source assembly 2 is additionally optimized, the illumination uniformity of the central field of view on the surface of the display screen 112 is determined by Figure 5 and Figure 6 It can be seen that after additional optimization of light source assembly 2, the illumination uniformity is improved to a certain extent. In addition, end-to-end design of the projection display system and external modulation such as flat field correction can achieve higher imaging quality and illumination uniformity.

[0111] The effective focal length of the above-mentioned projection display system provided in the embodiment of the present application is 5.0mm~9.5mm, and the focal length is jointly determined by the field of view angle of the imaging component 13 and the effective aperture of the display screen 112. The field of view angle of the projection display system is 20°~55°, and the exit pupil diameter of the projection display system is 2.5mm~4mm. The field of view angle and the effective aperture of the display screen 112 directly determine the volume of the projection display system. The selection of this field of view angle range can balance the imaging performance and structural compactness of the projection display system, and can realize the miniaturization design of the projection display system. When the field of view angle is 52°, the volume of the projection display system is less than 1.2 cubic centimeters, which can realize the miniaturization of the projection display system.

[0112] The present embodiment also simulates the optical performance of the projection display system. When the display element 11 comprises a protective glass 111 and a display screen 112, where the display screen 112 is a liquid crystal on silicon display, the surface parameters of the various optical components in the projection display system and the spacing between the optical components are shown in the following table:

[0113]

[0114] As shown in the table above, surfaces 1 to 10 are the optical surfaces of imaging assembly 13. Surfaces 1 and 2 are the two optical surfaces of single lens 133, surfaces 3 and 4 are the two optical surfaces of reflector 131, surfaces 5, 6, and 7 are the three optical surfaces of field lens 132, surfaces 8 and 9 are the two optical surfaces of protective glass 111, and surface 10 is the imaging reflective surface of the liquid crystal on silicon display. The thickness parameters corresponding to surfaces 1, 3, 5, 6, and 8 represent the distance from that surface to the next surface within the component. The thickness parameters corresponding to surfaces 2 and 7 represent the distance from the next component along the optical axis. "Next surface" refers to the subsequent surface of each component toward which light is transmitted.

[0115] Surfaces 11 to 19 are optical surfaces of the light source assembly 2. Surfaces 11 and 12 are the two optical surfaces of the relay lens 232, surfaces 13 and 14 are the two optical surfaces of the fly-eye lens, surfaces 15 and 16 are the two optical surfaces of the collimating lens assembly 234, surfaces 17 and 18 are the two optical surfaces of the protective glass 111, and surface 19 is the reflective surface of the silicon-based liquid crystal display. The thickness row parameters corresponding to surfaces 11, 13, 15, and 17 all represent the distance from the surface to the next surface within the component. The thickness row parameters corresponding to surfaces 12, 14, 16, and 18 all represent the distance from the component to the next component in the optical axis direction. The "next surface" refers to the subsequent surface of each component toward which light is transmitted.

[0116] The embodiment of the present application also evaluates the image quality of the projection display system based on the above parameter optimization results. Figure 7 , which is a structural diagram of a projection display system according to an embodiment of the present application. Figure 8 This is a modulation transfer function curve diagram of the projection display system provided in an embodiment of the present application.

[0117] Figure 8 The Modulation Transfer Function (MTF) curves of light with wavelengths of 460nm, 555nm, and 617nm in different fields of view are shown. Figure 8 It can be seen that the MTF values ​​of the light are all above 0.65 and the curve is relatively flat, indicating that the imaging difference between the edge and center of the projection display system is small and the imaging quality is good.

[0118] Figure 9 This is a standard mobile imaging architecture television distortion diagram of the projection display system provided in an embodiment of the present application.

[0119] Figure 9The following figure shows the Standard Mobile Imaging Architecture TV Distortion (SMIA TV) obtained by simulating the projection display system under the conditions of a wavelength of 555nm and a full field of view of 38.7°×29.5°. Figure 9 It can be seen that the absolute value of the SMIA TV distortion of the projection display system is less than 3.5%, and the geometric fidelity of the projection display system is good, meeting the imaging requirements.

[0120] Figure 10 This is a diagram of vertical axis chromatic aberration of the projection display system provided in an embodiment of the present application. Figure 10 The vertical axis chromatic aberration of light with wavelengths of 460nm, 555nm, and 617nm at different imaging sizes within a certain field of view is shown in the figure. Figure 10 As shown in the figure, the vertical axis chromatic aberration of the projection display system is less than 2.25μm, the light imaging is all within the radius of the Airy disk, and the imaging quality is good.

[0121] Figure 11 This is a relative illumination diagram of the projection display system provided in an embodiment of the present application. Figure 11 The relative illuminance of light with a wavelength of 555 nm is shown as Figure 11 As shown in the figure, when the field of view angle increases to 16°, the relative illumination only decreases to 0.94, which remains at a high level. This shows that the projection display system maintains excellent illumination uniformity within a larger field of view.

[0122] When the display element 11 uses a light field modulation element 113 and a display screen 112, the surface parameters of the projection display system and the spacing between the optical components are shown in the following table:

[0123]

[0124]

[0125] As shown in the table above, surfaces 1 to 10 are the optical surfaces of imaging assembly 13. Surfaces 1 and 2 are the two optical surfaces of single lens 133, surfaces 3 and 4 are the two optical surfaces of reflector 131, surfaces 5, 6, and 7 are the three optical surfaces of field lens 132, surfaces 8 and 9 are the two optical surfaces of light field modulation element 113, and surface 10 is the imaging surface of the display screen. The thickness row parameters corresponding to surfaces 1, 3, 5, 6, and 8 represent the distance from that surface to the next surface within the element. The thickness row parameters for surfaces 2, 7, and 9 represent the distance from that surface to the next element along the optical axis. The "next surface" refers to the subsequent surface of each element that faces light transmission.

[0126] Surfaces 11 to 19 are optical surfaces of the light source assembly 2. Surfaces 11 and 12 are the two optical surfaces of the relay lens 232, surfaces 13 and 14 are the two optical surfaces of the fly-eye lens, surfaces 15 and 16 are the two optical surfaces of the collimating lens assembly 234, surfaces 17 and 18 are the two optical surfaces of the protective glass 111, and surface 19 is the reflective surface of the liquid crystal on silicon display. The thickness row parameters corresponding to surfaces 11, 13, 15, and 17 all represent the distance from the surface to the next surface within the component. The thickness row parameters corresponding to surfaces 12, 14, 16, and 18 all represent the distance from the component to the next component in the optical axis direction. The "next surface" refers to the subsequent surface of each component toward which light is transmitted.

[0127] The embodiment of the present application also evaluates the image quality of the projection display system based on the above parameter optimization results. Figure 12 , which is a structural diagram of a projection display system according to an embodiment of the present application. Figure 13 This is a modulation transfer function curve diagram of the projection display system provided in an embodiment of the present application.

[0128] Figure 13 The Modulation Transfer Function (MTF) curves of light with wavelengths of 460nm, 555nm, and 617nm in different fields of view are shown. Figure 13 It can be seen that the MTF values ​​of the light are all above 0.65 and the curve is relatively flat, indicating that the imaging difference between the edge and center of the projection display system is small and the imaging quality is good.

[0129] Figure 14 This is a standard mobile imaging architecture television distortion diagram of the projection display system provided in an embodiment of the present application.

[0130] Figure 14 The following figure shows the Standard Mobile Imaging Architecture TV Distortion (SMIA TV) obtained by simulating the projection display system under the conditions of a wavelength of 555nm and a full field of view of 38.7°×38.7°. Figure 14 It can be seen that the absolute value of the SMIA TV distortion of the projection display system is less than 2.92%, and the geometric fidelity of the projection display system is good, meeting the imaging requirements.

[0131] Figure 15 This is a diagram of vertical axis chromatic aberration of the projection display system provided in an embodiment of the present application. Figure 15 The vertical axis chromatic aberration of light with wavelengths of 460nm, 555nm, and 617nm at different imaging sizes within a certain field of view is shown in the figure. Figure 15As shown in the figure, the vertical axis chromatic aberration of the projection display system is less than 2.25μm, the light imaging is all within the radius of the Airy disk, and the imaging quality is good.

[0132] Based on the same inventive concept, the embodiment of the present application further provides a near-eye display device, and the near-eye display device provided by the embodiment of the present application includes any of the above-mentioned projection display systems 1; in addition, the near-eye display device further includes: an optical waveguide component 3, such as Figure 16 Shown is a schematic structural diagram of the optical waveguide component 3.

[0133] The optical waveguide assembly 3 is located on the light-emitting side of the projection display system 1. It receives light emitted by the projection display system 1, conducts it, and two-dimensionally expands the pupil before emitting it toward the eye. Because the volume of the projection display system 1 is less than 1.2 cubic centimeters, it occupies a small space within a near-eye display device, enabling miniaturization of the device.

[0134] In some embodiments, the optical waveguide component 3 includes an optical waveguide 34 , an incoupling grating 31 , a turning grating 32 and an outcoupling grating 33 .

[0135] The optical waveguide 34 can be made of plastic, glass or other materials with high refractive index, such as Figure 16 As shown, the optical waveguide can be a spectacle lens or a helmet lens. Different refractive index materials are selected according to different viewing angles. When the viewing angle of the projection display system 1 is less than 30°, a plastic material with a relatively low refractive index is selected as the optical waveguide 34 to achieve high reliability and low cost of the near-eye display device. When the viewing angle of the projection display system 1 is greater than 30°, a high refractive index material such as a special high-refractive plastic material or high-refractive glass is selected. A material with a higher refractive index can produce a larger turning angle for light, thereby achieving higher imaging quality at a wider viewing angle.

[0136] The coupling-in grating 31, the turning grating 32 and the coupling-out grating 33 are all located on the optical waveguide 34. The coupling-in grating 31 is used to receive the light emitted by the projection display system 1 and couple it into the optical waveguide 34. The turning grating 32 is used to expand the pupil of the light emitted by the projection display system 1 along a first direction. The coupling-out grating 33 is used to expand the pupil of the light after the pupil is expanded along the first direction along a second direction, and couple it out of the optical waveguide 34 and emit it in the direction of the human eye. The first direction and the second direction are perpendicular to each other.

[0137] In order to improve the mass production yield and the diffraction efficiency of the optical waveguide 34, the coupling-in grating 31 can adopt a one-dimensional grating, the turning grating 32 can adopt a one-dimensional grating or a two-dimensional grating, and the coupling-out grating 33 can adopt a one-dimensional grating. The sum of the grating vector of the coupling-in grating 31, the grating vector of the turning grating 32 and the grating vector of the coupling-out grating 33 is 0.

[0138] The optical waveguide component 3 can be a single-sided grating on a single-layer plastic substrate, a double-sided grating on a single-layer high-refractive index substrate, a single-sided grating on a double-layer high-refractive index substrate, or a double-sided grating on a double-layer high-refractive index substrate. The grating can be a surface relief grating or a volume holographic grating. Different structures are selected based on the different wavelength requirements of the projection display system. When the projection display system only uses a single wavelength, the optical waveguide component 3 can be a single-sided grating on a single-layer substrate. When using multiple wavelengths, the optical waveguide component 3 needs to use a multi-sided grating on a single-layer or multi-layer substrate.

[0139] In some embodiments, the field of view angle of the optical waveguide component 3 is greater than or equal to the field of view angle of the projection display system 1, so that all light from the projection display system 1 can be incident on the optical waveguide component 3, avoiding assembly tolerances and preserving the field of view angle of the near-eye display device, thereby improving the diffraction efficiency of the optical waveguide 34.

[0140] In some embodiments, the light emitted by the projection display system 1 needs to be incident obliquely on the coupling grating 31. The shape of the coupling grating 31 can be circular, semicircular, or other irregular shapes. The size of the coupling grating 31 is larger than the exit pupil diameter of the projection display system 1, and the size of the coupling grating 31 is 2.7 mm to 4.2 mm. In the design of the optical waveguide 34, the 0th order diffraction light is usually suppressed during coupling, and the ±1st order diffraction light is preferentially used. The oblique incidence coupling grating 31 can avoid the 0th order diffraction light. In addition, the shape of the coupling grating 31 can also better avoid the 0th order diffraction light, improve the coupling efficiency of the ±1st order light, and thus improve the diffraction efficiency. The shape of the turning grating 32 and the coupling-out grating 33 can be rectangular, trapezoidal, or other irregular shapes, so as to maximize the range of the exit pupil of the optical waveguide 34, so as to maximize the area of ​​the coupling-out grating 33 and increase the visual range of the human eye.

[0141] The projection display system 1 provided in this embodiment has a volume of less than 1.2 cubic centimeters. The light output by the projection display system 1 is coupled to an optical waveguide assembly 3, which can be integrated into eyeglass lenses. The miniaturization of the projection display system 1, combined with the integrated design of the optical waveguide assembly 3 and the eyeglass lenses, enables a thin, lightweight, and compact near-eye display device.

[0142] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0143] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A projection display system, characterized in that: include: A display component for displaying images; A beam splitter prism located on the light-emitting side of the display element; The beam splitter prism comprises: a first surface, a second surface and a light-emitting surface; wherein the first surface and the second surface are arranged opposite to each other, and the light-emitting surface is connected to one end of the first surface and one end of the second surface respectively; and Imaging assembly; the imaging assembly includes: a reflector, a field lens and a single lens; The display element is arranged facing the first surface; the reflective surface of the reflector is arranged facing the second surface; the field lens is located between the display element and the first surface of the beam splitter prism; and the single lens is located on the light-emitting surface side of the beam splitter prism. The light emitted by the display element is incident on the dichroic prism, and is transmitted by the dichroic prism to the reflector. The reflector reflects the light, and the reflected light is incident on the dichroic prism again and is reflected by the dichroic prism toward the light output side of the projection display system.

2. The projection display system according to claim 1, wherein: The spectroscopic prism includes: two mutually opposing triangular prisms and a polarization spectroscopic layer located on the opposing surfaces of the two triangular prisms; the polarization spectroscopic layer is used to transmit the first linear polarized light and reflect the second linear polarized light; the polarization direction of the first linear polarized light is parallel to the incident plane of the incident light, and the polarization direction of the second linear polarized light is perpendicular to the incident plane of the incident light.

3. The projection display system according to claim 1, wherein: The reflector is a convex lens, and a reflective film is provided on the surface of the convex lens facing away from the dichroic prism; the surface of the reflector facing the dichroic prism is a curved surface or a flat surface; The field lens is a cemented lens; the surface of the field lens close to the beam splitter prism is a curved surface or a flat surface; The single lens is an aspherical lens; the effective focal length of the surface of the single lens away from the dichroic prism is smaller than the effective focal length of the surface of the single lens close to the dichroic prism; the surface of the single lens close to the dichroic prism is a curved surface or a flat surface.

4. The projection display system according to claim 2, wherein: The imaging assembly further comprises: an aperture, located on a side of the single lens facing away from the beam splitter prism; a phase compensator, located on the light-emitting side of the display element; the phase compensator is used to convert all the light emitted by the display element into the first linearly polarized light; a first phase retarder, located between the reflector and the beam splitter; the first phase retarder is used to convert the incident first linearly polarized light or the second linearly polarized light into circularly polarized light; and The second phase retarder is located between the beam splitter prism and the single lens; the second phase retarder is used to change the polarization direction of the incident light.

5. The projection display system according to any one of claims 1 to 4, wherein: The display element comprises: a display screen for displaying images; and a protective glass located on the light-emitting side of the display screen; Alternatively, the display element comprises: a display screen for displaying images; and A light field modulation element is located on the light-emitting side of the display screen; the light field modulation element is used to perform light field modulation on the light emitted from the display screen to achieve three-dimensional display.

6. The projection display system according to claim 5, wherein: The light field modulation element is a micro lens array or a cylindrical lens array.

7. The projection display system according to claim 5, wherein: The display screen is a liquid crystal display screen, an organic light emitting diode display screen or a micro light emitting diode display screen.

8. The projection display system according to claim 5, wherein: The display screen is a liquid crystal on silicon display screen; The beam splitter prism further comprises: a light incident surface; the light incident surface and the light emitting surface are arranged opposite to each other; The projection display system further comprises: A light source assembly is located on one side of the light incident surface of the beam splitter prism; the light source assembly is used to provide lighting for the display element.

9. The projection display system according to claim 8, wherein: The light source assembly comprises: a light source, located on one side of the light incident surface of the beam splitter prism; A shaping component is located between the light source and the beam splitter prism; the shaping component is used to shape and homogenize the output light of the light source; a polarizer, located between the shaping component and the beam splitter prism; a transmission axis of the polarizer is parallel to the polarization direction of the second linearly polarized light; The light source assembly also shares the field lens in the imaging assembly.

10. The projection display system according to claim 9, wherein: The shaping component comprises: a collimating lens group, located on the light-emitting side of the light source; the collimating lens group includes at least one lens, and the lens is an aspheric lens; a fly-eye lens, located on a side of the collimating lens group away from the light source; a relay lens, located on a side of the fly-eye lens away from the collimating lens group; The light homogenizing element is located between the relay lens and the polarizer; the light homogenizing element is a diffuser.

11. The projection display system according to any one of claims 1 to 5, wherein: The effective focal length of the projection display system is 5.0 mm to 9.5 mm.

12. The projection display system according to any one of claims 1 to 5, wherein: The viewing angle of the projection display system is 20° to 55°; The exit pupil diameter of the projection display system is 2.5 mm to 4 mm.

13. A near-eye display device, characterized in that: include: A projection display system, wherein the projection display system is the projection display system according to any one of claims 1 to 12; The optical waveguide component is located on the light-emitting side of the projection display system; the optical waveguide component is used to receive the light emitted by the projection display system, conduct it, expand the pupil in two dimensions, and emit it towards the human eye.

14. The near-eye display device according to claim 13, wherein: The optical waveguide assembly comprises: optical waveguides; A coupling-in grating is located on the optical waveguide; the coupling-in grating is used to receive the light emitted by the projection display system and couple it into the optical waveguide; a turning grating located on the optical waveguide; the turning grating is used to expand the pupil of the light emitted by the projection display system along a first direction; an outcoupling grating located on the optical waveguide; the outcoupling grating is used to expand the pupil of the light after the pupil is expanded along the first direction along a second direction, and couple the light out of the optical waveguide toward the human eye; the first direction and the second direction are perpendicular; The sum of the grating vector of the coupling-in grating, the grating vector of the turning grating, and the grating vector of the coupling-out grating is 0.

15. The near-eye display device according to claim 14, wherein: The viewing angle of the optical waveguide assembly is greater than or equal to the viewing angle of the projection display system; The size of the coupling-in grating is larger than the exit pupil diameter of the projection display system; the size of the coupling-in grating is 2.7 mm to 4.2 mm.

Images