An AR display device

Abstract

This invention discloses an AR display device, including a projection optical engine and a waveguide element. The waveguide element has an input facet that is inclined relative to the plane of the waveguide element. The output end of the waveguide element is provided with an output diffraction element parallel to the plane of the waveguide element, wherein the output diffraction element has optical power. The output end of the waveguide element also has a deflecting optical element. The projection optical engine outputs a projection beam to the input facet, causing the projection beam to undergo total internal reflection within the waveguide element. After being deflected by the deflecting optical element, the projection beam is incident on the output diffraction element with its principal ray perpendicular to the principal ray, and then diffracted by the output diffraction element in a direction perpendicular to the principal ray. This AR display device, while possessing a large field of view or refractive correction function, reduces the distortion of the projected image formed by the projection beam, improving the display effect and user experience.

Description

Technical Field

[0001] This invention relates to the field of AR display technology, and in particular to an AR display device. Background Technology

[0002] With the development of Augmented Reality (AR) display technology and its widespread application in gaming, entertainment, education, and other fields, users are placing higher and more diverse demands on display devices that implement AR technology. For example, implementing AR display technology on swimming goggles requires optical elements with a magnified field of view to maximize the display's field of view; these optical elements are typically optically potentiometric. Similarly, to ensure that users with refractive errors such as myopia or hyperopia can clearly see the projected image without wearing corrective glasses, AR display devices often require optically potentiometric elements to correct the wearer's refractive error. While these methods can meet the specific needs of users of AR display devices to some extent, optically potentiometric elements can also easily cause distortion in the projected image, thus reducing the display quality and user experience. Summary of the Invention

[0003] The purpose of this invention is to provide an AR display device that can improve the display effect of the projected image and enhance the user experience, while meeting the requirements of a large field of view or having refractive correction function.

[0004] To address the aforementioned technical problems, the present invention provides an AR display device, comprising a projection optical engine and a waveguide element; the coupling end of the waveguide element has a coupling end face inclined relative to the plane on which the waveguide element is located; the coupling end of the waveguide element is provided with a coupling out diffraction element parallel to the plane on which the waveguide element is located, wherein the coupling out diffraction element has optical power; the coupling end of the waveguide element is further provided with a deflection optical element;

[0005] The projection optical engine is used to output a projection beam to the coupling end face so that the projection beam is transmitted by total internal reflection in the waveguide element. After the projection beam is deflected by the deflecting optical element, the main ray is incident on the coupling diffraction element perpendicular to the coupling diffraction element. After being diffracted by the coupling diffraction element, the main ray is diffracted and output in a direction perpendicular to the coupling diffraction element.

[0006] In one optional embodiment of this application, the waveguide element includes a waveguide body having a first inclined surface and a compensation member having a second inclined surface; the waveguide body and the compensation member are connected to each other through the first inclined surface and the second inclined surface to jointly form the waveguide element, which is flat and has a uniform thickness.

[0007] The deflecting optical element is fitted between the first inclined surface and the second inclined surface, and the first inclined surface, the deflecting optical element and the second inclined surface are all inclined relative to the plane where the waveguide element is located.

[0008] The deflecting optical element is a polarization selector or a deflecting diffraction element.

[0009] In an optional embodiment of this application, the coupled-out diffraction element is a reflective diffraction element, and a first quarter-wave plate is further disposed between the surfaces of the coupled-out diffraction element and the waveguide element;

[0010] The polarization selector is a polarization beam splitter; the polarization beam splitter, the waveguide body having the end with the first inclined surface, and the compensation member having the end with the second inclined surface together form a PBS device;

[0011] The polarizing beam splitter is a film layer that reflects first linearly polarized light and transmits second linearly polarized light. The first linearly polarized light and the second linearly polarized light are orthogonal. The polarization direction of the first linearly polarized light is at a 45° angle to the fast axis direction of the first quarter-wave plate, so that the first linearly polarized light reflected by the polarizing beam splitter is transmitted through the first quarter-wave plate to form first circularly polarized light.

[0012] The coupled diffraction element is used to reflectively diffract the first circularly polarized light to output the second circularly polarized light; the polarization rotation directions of the first and second circularly polarized light are opposite.

[0013] In one optional embodiment of this application, a light-blocking polarizer is provided on the surface of the coupled diffraction element away from the waveguide element, for transmitting the second circularly polarized light and blocking the first circularly polarized light.

[0014] In one optional embodiment of this application, the light-blocking polarizer includes a second quarter-wave plate and a linear polarizer stacked together, which are attached to the surface of the coupled optical element facing away from the first quarter-wave plate.

[0015] The linear polarizer is a polarizer that blocks the second linearly polarized light and transmits the first linearly polarized light;

[0016] The fast axis direction of the second quarter-wave plate forms a 45° angle with the polarization direction of the linear polarizer, and is parallel to the fast axis direction of the first quarter-wave plate.

[0017] In an optional embodiment of this application, the coupled-out diffraction element is a reflective diffraction element, and a first quarter-wave plate is disposed between the surfaces of the coupled-out diffraction element and the waveguide element;

[0018] The polarization selector is a polarizing grating capable of reflective diffraction of circularly polarized light.

[0019] In an optional embodiment of this application, the first inclined surface and the second inclined surface are inclined curved surfaces with the same surface shape; the polarization selector is a curved polarization element with the same surface shape as the first inclined surface.

[0020] In an optional embodiment of this application, a light-transmitting medium layer is disposed between the surface of the first quarter-wave plate and the waveguide element; the refractive index of the light-transmitting medium layer is less than the refractive index of the waveguide element; and the critical angle of the light-transmitting medium layer with respect to the waveguide element is less than the total internal reflection incident angle of the projection beam transmitted through the waveguide element.

[0021] In one optional embodiment of this application, the coupled diffraction element is a transmission diffraction element;

[0022] The deflecting optical element is a deflecting diffraction element, and the dispersion characteristics of the deflecting diffraction element for different wavelengths are opposite to those of the coupled diffraction element for different wavelengths.

[0023] In one optional embodiment of this application, the projection optical engine includes a projection light source and a shaping element; the shaping element is disposed in the optical path between the projection light source and the coupling end face, and is used to modulate the projection beam output by the projection light source so that the projection beam is coupled into the waveguide element through the coupling end face to form a parallel beam.

[0024] The present invention provides an AR display device, comprising a projection optical engine and a waveguide element; the coupling end of the waveguide element has a coupling end face inclined relative to the plane on which the waveguide element is located; the coupling end of the waveguide element is provided with a coupling out diffraction element parallel to the plane on which the waveguide element is located, wherein the coupling out diffraction element has optical power; the coupling end of the waveguide element is also provided with a deflecting optical element; wherein the projection optical engine is used to output a projection beam to the coupling end face, so that the projection beam is transmitted by total internal reflection within the waveguide element, and after being deflected by the deflecting optical element, the projection beam is incident on the coupling out diffraction element with the principal ray perpendicular to the coupling out diffraction element, and diffracted by the coupling out diffraction element in a direction with the principal ray perpendicular to the coupling out diffraction element.

[0025] The AR display device of this application includes an optically powerful coupled-out diffraction element at the coupling end of the waveguide element. This allows the AR display device to have a relatively large field of view or to correct refractive errors in the wearer. Furthermore, a deflecting optical element is provided at the coupling end of the waveguide element to deflect the propagation direction of the projection beam transmitted by total internal reflection within the waveguide element. This allows the projection beam to be deflected by the deflecting optical element and then incident on the coupled-out diffraction element with its principal ray perpendicular to the element. It also diffracts and couples out from the coupled-out diffraction element with its principal ray perpendicular to the element. Therefore, the projection beam in this application is incident on the optically powerful coupled-out diffraction element in a roughly perpendicular direction and is diffracted and coupled out from the coupled-out diffraction element in a roughly perpendicular direction. This significantly reduces the dispersion and distortion caused by diffraction of the projection beam through the coupled-out diffraction element, thereby improving the imaging effect of the projected image formed after the projection beam is coupled out of the waveguide element, which is beneficial to improving the user experience of the AR display device. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the first optical path structure of the AR display device provided in the embodiments of this application;

[0028] Figure 2 This is a schematic diagram of a second optical path structure for an AR display device provided in an embodiment of this application;

[0029] Figure 3 This is a schematic diagram of a third optical path structure for an AR display device provided in an embodiment of this application;

[0030] Figure 4 This is a schematic diagram of a fourth optical path structure for an AR display device provided in an embodiment of this application;

[0031] Figure 5 This is a schematic diagram of the fifth optical path structure of the AR display device provided in the embodiments of this application;

[0032] Figure 6 This is a schematic diagram of the sixth optical path structure of the AR display device provided in the embodiments of this application;

[0033] Figure 7 This is a schematic diagram of the seventh optical path structure of the AR display device provided in the embodiments of this application;

[0034] Figure 8 This is a schematic diagram of a partial optical path structure in an AR display device provided in an embodiment of this application;

[0035] Figure 9 This is a schematic diagram of the optical path structure of the light-blocking polarizer provided in the embodiments of this application;

[0036] Figure 10 This is a schematic diagram of the eighth optical path structure of the AR display device provided in the embodiments of this application;

[0037] In the attached figures: 10 is a waveguide element, 101 is a coupling end face, 11 is a waveguide body, 12 is a compensation component, 20 is a projection optical engine, 21 is a projection light source, 22 is a shaping lens, 23 is a transmission polarizer, 24 is a reflection polarizer, 3 is a coupling out diffraction element, 41 is a polarization beam splitter, 42 is a polarizing grating, 43 is a deflection diffraction element, 5 is a first quarter-wave plate, 6 is a light-blocking polarizer, 61 is a second quarter-wave plate, and 62 is a linear polarizer. Detailed Implementation

[0038] The core of this invention is to provide an AR display device that can improve the imaging effect of projected images to a certain extent.

[0039] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] like Figures 1 to 10 As shown, Figure 1 This is a schematic diagram of the first optical path structure of the AR display device provided in the embodiments of this application; Figure 2 This is a schematic diagram of a second optical path structure for an AR display device provided in an embodiment of this application; Figure 3 This is a schematic diagram of a third optical path structure for an AR display device provided in an embodiment of this application; Figure 4 This is a schematic diagram of a fourth optical path structure for an AR display device provided in an embodiment of this application; Figure 5 This is a schematic diagram of the fifth optical path structure of the AR display device provided in the embodiments of this application; Figure 6 This is a schematic diagram of the sixth optical path structure of the AR display device provided in the embodiments of this application; Figure 7 This is a schematic diagram of the seventh optical path structure of the AR display device provided in the embodiments of this application; Figure 8 This is a schematic diagram of a partial optical path structure in an AR display device provided in an embodiment of this application; Figure 9 This is a schematic diagram of the optical path structure of the light-blocking polarizer provided in the embodiments of this application; Figure 10 This is a schematic diagram of the eighth optical path structure of the AR display device provided in the embodiments of this application.

[0041] In one specific embodiment of this application, the AR display device may include:

[0042] Projection optical engine 20 and waveguide element 10;

[0043] The waveguide element 10 has a coupling end face 101 that is inclined relative to the plane on which the waveguide element 10 is located; the waveguide element 10 has a coupling end face 101 that is parallel to the plane on which the waveguide element 10 is located at the coupling end, wherein the coupling end face 3 has optical power; the waveguide element 10 also has a deflection optical element at the coupling end.

[0044] The projection optical engine 20 is used to output a projection beam to the coupling end face 101 so that the projection beam is transmitted by total internal reflection in the waveguide element 10. After the projection beam is deflected by the deflection optical element, the main ray is incident on the coupling diffraction element 3 perpendicular to the coupling diffraction element 3. After being diffracted by the coupling diffraction element 3, the main ray is diffracted and output in the direction perpendicular to the coupling diffraction element 3.

[0045] like Figure 1 As shown, the AR display device in this embodiment mainly includes a projection optical engine 20 and a waveguide element 10. The projection optical engine 20 is the light source device for outputting the projection beam, while the waveguide element 10 can be a generally transparent flat plate structure, similar to the structure of eyeglass lenses, and can also be called a waveguide lens. The projection beam output by the projection optical engine 20 is coupled into the waveguide element 10 through the coupling end, and after undergoing at least one total internal reflection transmission within the waveguide element 10, it is conducted to the coupling end of the waveguide element 10, and then coupled out to the human eye through the coupling end of the waveguide element 10, so that the user can view the projected image formed by the projection beam.

[0046] It is understandable that in this application Figure 1 The accompanying figures only show the optical path structure for outputting the projected image to a single eye of the user. If it is necessary to project the image to both eyes of the user, the optical path structures corresponding to each eye can be the same and symmetrically set. This will not be described in detail in this application.

[0047] The projection optical engine 20 in this embodiment may include a projection light source 21 and a shaping element. The shaping element is disposed in the optical path between the projection light source 21 and the coupling end face 101. The shaping element may include at least one of the optical elements, namely a shaping lens 22 or a reflecting element, so that the projection beam output by the projection light source 21 is shaped and modulated by the shaping element and then incident into the waveguide element 10 to form a parallel beam or a beam with a relatively small divergence angle.

[0048] Furthermore, in this embodiment, the coupling end of the waveguide element 10 has a coupling end face 101 that is inclined relative to the plane on which the waveguide element 10 is located, that is, the coupling end face 101 is an inclined surface at the end of the waveguide element 10; thus, the projection beam can be incident on the waveguide element 10 in a direction perpendicular to the main ray and the coupling end face 101, which means that the projection beam is incident obliquely into the waveguide element 10 and transmitted by total internal reflection within the waveguide element 10.

[0049] In this embodiment, the coupling end face 101 on the waveguide element 10 can be an inclined plane, and the inclination angle between the inclined plane and the plane where the waveguide element 10 is located can be determined based on the total internal reflection angle of the projection beam propagating within the waveguide. As described above, the projection beam in this embodiment needs to be transmitted within the waveguide element 10 in the form of parallel light. When the coupling end face 101 of the waveguide element 10 is an inclined plane, the shaping element can be an optical element that modulates the projection beam into a parallel beam. The projection beam can be perpendicular to the coupling end face 101, or it can be incident on the coupling end face 101 at a specific incident angle, as long as it is ensured that the projection beam can be transmitted within the waveguide element 10 after being transmitted through the coupling end face 101.

[0050] Furthermore, the coupling end face 101 on the waveguide element 10 in this embodiment can also be an inclined curved surface; such as Figure 1 and Figure 3As shown, the coupling end face 101 can be a convex curved surface that is inclined towards the side of the waveguide element 10 closer to the human eye, or it can be a convex curved surface that is inclined away from the side of the waveguide element 10 away from the human eye. At this time, the coupling end of the waveguide element 10 is equivalent to a structure in which an inclined plane and a convex lens are integrally formed. That is, the coupling end face 101 of the waveguide element 10 also has a modulation effect on the divergence angle of the projected light, so that it can cooperate with the shaping element in the projection optical engine 20 to modulate the projected light beam incident on the waveguide element 10 through the coupling end face 101 into a parallel light beam, thereby enabling the projected light beam to be transmitted in the waveguide element 10 with total internal reflection as parallel light. It is understood that the coupling end face 101 in this application can also be a concave curved surface. In this case, it is equivalent to the structure of the inclined plane and the concave lens being integrally formed at the coupling end of the waveguide element 10. It also has the function of adjusting the divergence angle of the projected light. In addition, the coupling end face 101 of the waveguide element 10 can also cooperate with the shaping lens 22 in the projection optical engine 20 to modulate and shape the projected beam.

[0051] It is understood that in another optional embodiment of this application, the projection beam output by the projection optical engine 20 is not necessarily transmitted by total internal reflection in the waveguide element 10 in the form of parallel light. The projection beam can also be a beam with a relatively small divergence angle transmitted by total internal reflection in the waveguide element 10. In this case, the shaping element and the coupling end of the waveguide element 10 can be optical elements for correcting the distortion of the projection beam.

[0052] Based on this, the waveguide element 10 in this embodiment is further provided with a coupling-out diffraction element 3. When the projected beam is transmitted to the output end of the waveguide element 10 by total internal reflection and is incident on the coupling-out diffraction element 3, the coupling-out diffraction element 3 diffracts and couples out the projected beam, so that the projected beam can be incident on the human eye.

[0053] Based on the above discussion, in order to expand the field of view of the AR display device to a certain extent, or to correct the user's refractive error, the coupling diffraction element 3 in this application can be a diffraction element with optical power, that is, it can modulate the divergence angle of the projected light. However, in the process of diffracting and coupling the projected light beam, the coupling diffraction element 3 with optical power often easily introduces problems such as distortion and color difference into the projected light beam, thereby reducing the imaging effect of the projected image to a certain extent.

[0054] Therefore, in order to reduce the distortion introduced by the coupling-out diffraction element 3 to the diffraction of the projected beam, this application further provides a deflection optical element at the coupling end of the waveguide element 10. This deflection optical element can deflect the transmission direction of the projected beam transmitted by total internal reflection within the waveguide element 10. When the projected beam is a parallel beam within the waveguide element 10, the deflection optical element allows the projected beam to be incident perpendicularly to the coupling-out diffraction element 3. When the projected beam is a beam with a small divergence angle propagating within the waveguide element 10, the deflection optical element allows the principal ray of the projected beam to be incident perpendicularly to the coupling-out diffraction element 3. For ease of discussion, the following explanation will only use the example of the projected beam being perpendicular to the coupling-out diffraction element 3.

[0055] It is understandable that the optical power of a diffractive element is determined by the quadratic term of the phase distribution, while higher-order terms (such as fourth-order and sixth-order terms) are the root cause of aberrations (including distortion). When a beam of light is incident perpendicularly to a diffractive element with optical power, the light only involves a small range of r-values ​​(paraxial region), and the influence of higher-order terms is negligible, especially since the distortion of monochromatic light approaches zero. However, when the light is incident obliquely to a diffractive element with optical power, the contribution of higher-order terms in phase modulation increases significantly, resulting in a greater degree of distortion in the image formed by the light.

[0056] Therefore, based on the above principle, this application uses a deflecting optical element to deflect the transmission direction of the projection beam, so that the projection beam can be incident perpendicularly on the coupling diffraction element 3 and diffracted out in a direction perpendicular to the coupling diffraction element 3. This greatly reduces the distortion introduced by the coupling diffraction element 3 during the diffraction of the projection beam, thereby improving the display effect of the projection image formed by the projection beam.

[0057] In the AR display device of this application, the deflection optical element can be implemented in a variety of different ways, which will be described below with specific embodiments.

[0058] In an optional embodiment of the AR display device of this application, the waveguide element 10 may include:

[0059] A waveguide body 11 with a first inclined surface and a compensation component 12 with a second inclined surface; the waveguide body 11 and the compensation component 12 are connected to each other through the first and second inclined surfaces to form a waveguide element 10 with a flat plate shape and uniform thickness.

[0060] The deflecting optical element is attached between the first inclined surface and the second inclined surface, and the first inclined surface, the deflecting optical element and the second inclined surface are all inclined relative to the plane where the waveguide element 10 is located.

[0061] The deflecting optical element is a polarization selector or a deflecting diffraction element 43.

[0062] In this embodiment, the waveguide element 10 can be divided into two parts: a waveguide body 11 and a compensation element 12. The compensation element 12 is a small part of the light-transmitting structure at the coupling end of the waveguide element 10. The dividing interface between the waveguide body 11 and the compensation element 12 is inclined to the plane where the waveguide element 10 is located, thereby forming a first inclined surface at the end of the waveguide body 11 and a second inclined surface at the end of the compensation element 12. The deflection optical element is disposed between the first and second inclined surfaces, which is equivalent to embedding the deflection optical element inside the coupling end of the waveguide element 10. The plane where the deflection optical element is located is inclined to the plane where the waveguide element 10 is located. The tilt angle of the deflection optical element relative to the waveguide element 10 is determined based on the angle of total internal reflection transmission of the projected beam within the waveguide element 10.

[0063] Based on this, the deflection optical element in this embodiment can be a polarization selector or a deflection diffraction element 43. It can be understood that a polarization selector is a polarization device that selectively reflects light with a specific polarization direction in the projection beam; while the deflection diffraction element 43 achieves deflection of the transmission direction of the projection beam through diffraction.

[0064] In practical applications, the type of deflecting optical element can vary depending on the type of the coupled-out diffraction element 3. For example, when the coupled-out diffraction element 3 is a reflective diffraction element disposed on the surface of the waveguide element 10 facing away from the human eye, the deflecting optical element is a polarization selector. However, when the coupled-out diffraction element 3 is a transmissive diffraction element disposed on the surface of the waveguide element 10 close to the human eye, the deflecting optical element can be either a polarization selector or a deflecting diffraction element 43 without polarization selection function. The following will describe various implementation methods using specific embodiments.

[0065] Reference Figure 1 and Figure 3 In an optional embodiment of this application, the coupled-out diffraction element 3 can be a reflective diffraction element, and a first quarter-wave plate 5 is also provided between the coupled-out diffraction element 3 and the surface of the waveguide element 10.

[0066] The polarization selector is a polarization beam splitter 41; the polarization beam splitter 41, the end of the waveguide body 11 with a first inclined surface, and the end of the compensation member 12 with a second inclined surface together form a PBS device;

[0067] Among them, the polarization beam splitter 41 is a film layer that reflects the first linearly polarized light and transmits the second linearly polarized light. The first linearly polarized light and the second linearly polarized light are orthogonal. The polarization direction of the first linearly polarized light and the fast axis direction of the first quarter-wave plate 5 are at an angle of 45°, so that the first linearly polarized light reflected by the polarization beam splitter 41 is transmitted through the first quarter-wave plate 5 to form the first circularly polarized light.

[0068] The coupled diffraction element 3 is used to reflect and diffract the first circularly polarized light to output the second circularly polarized light; the polarization rotation directions of the first and second circularly polarized lights are opposite.

[0069] like Figure 1 As shown, this embodiment uses a reflective diffraction element 3 as an example for explanation. Furthermore, the polarization selector in this embodiment is a polarization beam splitter 41, disposed between the first inclined surface of the waveguide body 11 and the second inclined surface of the compensation element 12. The polarization beam splitter 41, the wedge-shaped ends of the waveguide body 11 and the compensation element 12 interconnect to form a device similar to a PBS (polarizing beam splitter prism). Of course, the angle between the plane containing the polarization beam splitter 41 and the waveguide element 10 in this embodiment is not necessarily 45°; it should be sufficient to ensure that the projected beam incident on the polarization beam splitter 41 is reflected and perpendicularly incident on the coupling diffraction element 3.

[0070] Based on this, the polarization beam splitter 41 in this embodiment can be a film layer that reflects the first linearly polarized light and transmits the second linearly polarized light; and the fast axis direction of the first quarter-wave plate 5 and the polarization direction of the first linearly polarized light that can be reflected by the polarization beam splitter 41 form a 45° angle. Thus, in practical applications, when the projection beam is transmitted to the polarization beam splitter 41 by total internal reflection within the waveguide element 10, the polarization beam splitter 41 can reflect the first linearly polarized light in the projection beam, so that the first linearly polarized light in the projection beam is perpendicularly coupled out of the diffraction element 3 and incident. Obviously, the first linearly polarized light is incident on the first quarter-wave plate 5 before it is incident on the coupler diffraction element 3. Since the polarization direction of the first linearly polarized light is at a 45° angle to the fast axis of the first quarter-wave plate 5, the first linearly polarized light can be transmitted through the first quarter-wave plate 5 to form the first circularly polarized light. The first circularly polarized light is incident perpendicularly on the coupler diffraction element 3. After the coupler diffraction element 3 performs reflection diffraction on the first circularly polarized light, it outputs the second circularly polarized light. After the second circularly polarized light is transmitted through the first quarter-wave plate 5, it can form the second linearly polarized light orthogonal to the first linearly polarized light. Thus, the second linearly polarized light can be transmitted through the polarization beam splitter 41, and finally the second linearly polarized light is transmitted through the coupler end of the waveguide element 10 and the polarization beam splitter 41 to be output to the human eye.

[0071] Optionally, such as Figure 4 and Figure 5As shown, in practical applications, a transmission polarizer 23 or a reflection polarizer 24 can be built into the projection optical engine 20 to modulate the projection beam output from the projection light source 21 into first linearly polarized light. This first linearly polarized light is incident on the waveguide element 10 after passing through a shaping element, and after total internal reflection in the waveguide element 10, it is incident on the polarization beam splitter 41. Of course, it is not necessary to set a transmission polarizer 23 or a reflection polarizer 24 in the projection optical engine 20. When the projection beam output from the projection optical engine 20 is incident on the polarization beam splitter 41 in the state of natural light, the polarization beam splitter 41 can reflect only the first linearly polarized light and transmit the other part of the light, and can also output the first linearly polarized light perpendicularly to the coupling out diffraction element 3.

[0072] In addition, such as Figure 1 As shown, if the first quarter-wave plate 5, which is disposed between the coupling diffraction element 3 and the waveguide element 10, is directly attached to the surface of the waveguide element 10, the projected beam may be incident on the optical interface region where the first quarter-wave plate 5 is attached during the total internal reflection propagation process in the waveguide element 10, thereby interfering with the propagation of the projected beam.

[0073] Therefore, in another optional implementation of this embodiment, a light-transmitting medium layer can be further provided between the first quarter-wave plate 5 and the waveguide element 10; the refractive index of the light-transmitting medium layer is less than the refractive index of the waveguide element 10; and the critical angle of the light-transmitting medium layer with respect to the waveguide element 10 is less than the total reflection incident angle of the projection beam transmitted by total reflection in the waveguide element 10; thereby avoiding interference of the first quarter-wave plate 5 with the total reflection transmission of the projection beam.

[0074] In practical applications, the light-transmitting medium layer can be an air medium layer, that is, an air gap is left between the first quarter-wave plate 5 and the waveguide element 10; of course, the light-transmitting medium layer can also be a light-transmitting adhesive layer disposed between the first quarter-wave plate 5 and the waveguide element 10. The refractive index of the light-transmitting adhesive layer is less than that of the waveguide element 10. It can avoid the first quarter-wave plate 5 from interfering with the total internal reflection transmission of the projection beam, and also serve as an adhesive layer connecting the first quarter-wave plate 5 and the waveguide element 10.

[0075] Based on the above discussion, this embodiment further considers that the diffraction efficiency of the coupled diffraction element 3 is difficult to reach 100% for the first circularly polarized light. The first circularly polarized light that is not diffracted continues to propagate along the original direction, causing light leakage. Light leakage may cause the projected image output by the AR display device to be seen by people other than the wearer, which not only affects the aesthetics but also poses a risk of privacy leakage.

[0076] Therefore, such as Figure 7 and Figure 8As shown, in another optional embodiment of this application, a light-blocking polarizer 6 is further provided on the surface of the coupled diffraction element 3 facing away from the waveguide element 10. The light-blocking polarizer 6 is used to transmit the second circularly polarized light while blocking the first circularly polarized light.

[0077] Therefore, as Figure 8 As described above, when the first circularly polarized light is incident perpendicularly to the coupled-out diffraction element 3, most of the first circularly polarized light is reflected and diffracted by the coupled-out diffraction element 3 to form second circularly polarized light, which is then incident on the first quarter-wave plate 5. A small portion of the first circularly polarized light is transmitted through the coupled-out diffraction element 3 and then incident on the light-blocking polarizer 6, where it is blocked to prevent light leakage. Furthermore, the second circularly polarized light in the ambient light can be transmitted sequentially through the light-blocking polarizer 6 and the coupled-out diffraction element 3, and after passing through the first quarter-wave plate 5 to form second linearly polarized light, it can also be transmitted through the waveguide element 10 and incident on the human eye. Therefore, the light-blocking polarizer 6 in this embodiment not only prevents light leakage from the projected beam but also avoids completely blocking ambient light, effectively ensuring the display effect of the AR display device.

[0078] Further as Figure 9 As shown, the light-blocking polarizer 6 may include a second quarter-wave plate 61 and a linear polarizer 62 stacked on the surface of the optical element that is attached to the side opposite to the first quarter-wave plate 5.

[0079] The linear polarizer 62 is a polarizer that blocks the second linearly polarized light and transmits the first linearly polarized light;

[0080] The fast axis direction of the second quarter-wave plate 61 forms a 45° angle with the polarization direction of the linear polarizer 62, and is perpendicular to the fast axis direction of the first quarter-wave plate 5.

[0081] like Figure 9 As shown, the first circularly polarized light transmitted from the coupled diffraction element 3 is incident on the second quarter-wave plate 61, and after passing through the second quarter-wave plate 61, it can form the second linearly polarized light; while the linear polarizer 62 attached to the second quarter-wave plate 61 blocks the second linearly polarized light, thereby avoiding the problem of light leakage of the second linearly polarized light.

[0082] In addition, the first linearly polarized light in the ambient light can be transmitted through the linear polarizer 62 and incident on the second quarter-wave plate 61. After being transmitted through the second quarter-wave plate 61, it forms the second circularly polarized light, which can then be transmitted through the coupled diffraction element 3 and the waveguide element 10 and incident on the human eye, thereby ensuring that the wearer can see the ambient light.

[0083] In the above embodiments, the coupled-out diffraction element 3 is an element that can diffract circularly polarized light. However, in practical applications, the coupled-out diffraction element 3 can also be an element that can diffract linearly polarized light.

[0084] Therefore, as Figure 3 As shown, in another optional embodiment of this application, the coupled-out diffraction element 3 can be a diffraction element that reflects and diffracts the first linearly polarized light and outputs the second linearly polarized light. In this case, the polarization beam splitter 41 is a film that reflects the first linearly polarized light and transmits the second linearly polarized light. In this case, it is not necessary to provide the first quarter-wave plate 5 between the coupled-out diffraction element 3 and the waveguide element 10.

[0085] Therefore, in this embodiment, the projected beam is transmitted through total internal reflection in the waveguide element 10 and then to the polarization beam splitter 41. The polarization beam splitter 41 reflects the first linearly polarized light in the projected beam, so that the first linearly polarized light is perpendicularly incident on the coupling diffraction element 3. The coupling diffraction element 3 performs reflective diffraction on the first linearly polarized light and outputs the second linearly polarized light. The second linearly polarized light can be incident on the human eye after passing through the polarization beam splitter 41 and the waveguide element 10.

[0086] Furthermore, to prevent some of the first linearly polarized light from being transmitted and leaking through the coupling diffraction element 3, a linear polarizer 62 can be provided on the side of the coupling diffraction element 3 facing away from the waveguide element 10 to block the first linearly polarized light while allowing the second linearly polarized light to pass through. Additionally, an air gap or a transparent adhesive layer with a refractive index lower than that of the waveguide element 10 can be left between the coupling diffraction element 3 and the waveguide element 10 to prevent total internal reflection interference from the coupling diffraction element 3 on the projected beam.

[0087] Based on the above discussion, when the deflection optical element in this application is a polarization selector, the polarization selector is not limited to using a polarization beam splitter 41.

[0088] like Figure 4 As shown, in another optional embodiment of this application, the polarization selector may also be a polarization body grating 42, which is a polarization body grating 42 capable of reflective diffraction of circularly polarized light; the coupled diffraction element 3 is a reflective diffraction element, and a first quarter-wave plate 5 is disposed between the coupled diffraction element 3 and the surface of the waveguide element 10.

[0089] In this embodiment, the polarizing grating 42 is a grating element capable of reflective diffraction of circularly polarized light. Specifically, it can be a grating that reflects and diffracts the first circularly polarized light while transmitting the second circularly polarized light, with the polarization rotation directions of the first and second circularly polarized light being opposite. The coupled-out diffraction element 3 is a diffraction element capable of reflecting and diffracting the second linearly polarized light and outputting the second linearly polarized light. Thus, when the projected beam is transmitted through total internal reflection within the waveguide element 10 and incident on the polarizing grating 42, the polarizing grating 42 can reflect and diffract the first circularly polarized light in the projected beam and output the second circularly polarized light. The second circularly polarized light is transmitted through the first quarter-wave plate 5 and becomes the second linearly polarized light. The second linearly polarized light is perpendicularly incident on the coupled-out diffraction element 3 for reflective diffraction and is output perpendicularly. The second linearly polarized light is transmitted through the first quarter-wave plate 5 again and becomes the second circularly polarized light again. The second circularly polarized light is transmitted through the polarizing grating 42 and the waveguide element 10 and can then be incident on the human eye.

[0090] like Figure 3 and Figure 5 As shown, when the coupled-out diffraction element 3 is a reflective diffraction element, the polarization selector in this application, whether it is the polarization beam splitter 41 or the polarization grating 42, can be a polarization element that reflects the first linearly polarized light and transmits the second linearly polarized light. At the same time, the coupled-out diffraction element 3 can be a diffraction element that performs reflective diffraction on the first linearly polarized light and then outputs the second linearly polarized light. In this case, there is no need to set the first quarter-wave plate 5 between the coupled-out diffraction element 3 and the waveguide element 10. When the projection beam is transmitted through total internal reflection in the waveguide element 10 and is directed to the polarization selector (which can be either the polarization beam splitter 41 or the polarization grating 42), the polarization selector can reflectively diffract the first linearly polarized light in the projection beam and then perpendicularly incident on the coupled-out diffraction element 3. The coupled-out diffraction element 3 reflectsively diffracts the first linearly polarized light and outputs the second linearly polarized light. The second linearly polarized light is transmitted through the polarization selector and the waveguide element 10 and can then enter the human eye.

[0091] Based on any of the above embodiments, regardless of whether the polarization selector in the above embodiments is a polarization beam splitter 41 or a polarization grating 42, as shown in the figure, the first and second inclined surfaces connected between the waveguide body 11 and the compensation element 12 can be inclined curved surfaces with the same surface shape; correspondingly, the polarization selector is a curved polarization element with the same surface shape as the first and second inclined surfaces. At this time, the end of the waveguide body 11 near the compensation element 12 is equivalent to a convex or concave lens structure relative to the projection beam, which can also play a role in modulating the divergence angle of the projection beam and correcting the distortion of the projection beam to a certain extent, thereby improving the final imaging effect of the projection beam to a certain extent.

[0092] The above embodiments are illustrated using the example of a reflective diffraction element 3 as the coupled-out diffraction element. In practical applications, the coupled-out diffraction element 3 in this application can also be a transmission diffraction element disposed on the surface of the waveguide element 10 near the human eye.

[0093] like Figure 2 and Figure 10 As shown, in an optional embodiment of this application, the coupled-out diffraction element 3 is a transmission diffraction element;

[0094] Accordingly, the deflecting optical element is a deflecting diffraction element 43, and the dispersion characteristics of the deflecting diffraction element 43 for different wavelengths are opposite to those of the coupled diffraction element 3 for different wavelengths.

[0095] like Figure 2 As shown, the deflection diffraction element 43 in this embodiment can be a transmission diffraction element, such as... Figure 10 As shown, the deflection diffraction element 43 in this embodiment can also be a reflection diffraction element. In short, as long as the projected beam incident on the deflection diffraction element 43 is diffracted, it can be perpendicularly incident on the coupling diffraction element 3 and output to the human eye through the transmission diffraction of the coupling diffraction element 3 in a direction perpendicular to the coupling diffraction element 3.

[0096] Furthermore, as mentioned above, the coupled-out diffraction element 3 with optical power has a better effect on reducing distortion of the perpendicularly incident projection beam, especially the distortion correction effect of light of the same color wavelength is better. Therefore, the deflection diffraction element 43 in this embodiment specifically targets the dispersion characteristics generated by diffraction of light of different wavelengths, which is opposite to the dispersion characteristics generated by the coupled-out diffraction element 3 for diffraction of light of different wavelengths; for example, when the incident angle is the same, the diffraction angle output by the coupled-out diffraction element 3 for diffracting red, green and blue light increases sequentially; while when the incident angle is the same, the diffraction angle output by the deflection diffraction element 43 for diffracting red, green and blue light decreases sequentially; thus, the coupled-out diffraction element 3 and the deflection diffraction element 43 can complement the dispersion of light of different wavelengths in the projection beam during the diffraction of the projection beam, thereby further improving the display effect formed by the projection beam.

[0097] It is understood that when the coupled-out diffraction element 3 is a transmission diffraction element, the deflection optical element in this embodiment can also be a polarizer grating 42, so that only light rays with a specific polarization direction in the projection beam are diffracted and incident on the coupled-out diffraction element 3. As long as at least part of the light rays in the projection beam are perpendicularly incident on the coupled-out diffraction element 3, and are transmitted and diffracted through the coupled-out diffraction element 3 and vertically output to the human eye, this application does not specifically limit this.

[0098] In summary, the AR display device of this application includes an optically powerful coupled-out diffraction element at the coupling end of the waveguide element. This allows the AR display device to have a relatively large field of view or to correct refractive errors in the wearer. Furthermore, a deflecting optical element is provided at the coupling end of the waveguide element to deflect the propagation direction of the projection beam transmitted by total internal reflection within the waveguide element. This allows the projection beam to be deflected by the deflecting optical element and then incident on the coupled-out diffraction element with its principal ray perpendicular to the element. The beam then diffracts and couples out from the coupled-out diffraction element with its principal ray perpendicular to the element. Therefore, the projection beam in this application is incident on the optically powerful coupled-out diffraction element in a roughly perpendicular direction and is also diffracted and couples out from the coupled-out diffraction element in a roughly perpendicular direction. This significantly reduces the dispersion and distortion caused by diffraction of the projection beam through the coupled-out diffraction element, thereby improving the imaging effect of the projected image formed after the projection beam is coupled out of the waveguide element, which is beneficial for enhancing the user experience of the AR display device.

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0100] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. An AR display device, characterized in that, It includes a projection optical engine and a waveguide element; the coupling end of the waveguide element has a coupling end face that is inclined relative to the plane on which the waveguide element is located; the coupling end of the waveguide element is provided with a coupling out diffraction element that is parallel to the plane on which the waveguide element is located, wherein the coupling out diffraction element has optical power; the coupling end of the waveguide element is also provided with a deflection optical element. The projection optical engine is used to output a projection beam to the coupling end face so that the projection beam is transmitted by total internal reflection in the waveguide element. After the projection beam is deflected by the deflecting optical element, the main ray is incident on the coupling diffraction element perpendicular to the coupling diffraction element. After being diffracted by the coupling diffraction element, the main ray is diffracted and output in a direction perpendicular to the coupling diffraction element. The waveguide element includes a waveguide body with a first inclined surface and a compensation component with a second inclined surface; the waveguide body and the compensation component are connected to each other through the first inclined surface and the second inclined surface to form the waveguide element, which is flat and has a uniform thickness. The deflecting optical element is fitted between the first inclined surface and the second inclined surface, and the first inclined surface, the deflecting optical element and the second inclined surface are all inclined relative to the plane where the waveguide element is located. The deflecting optical element is a polarization selector or a deflecting diffraction element.

2. The AR display device as described in claim 1, characterized in that, The coupled-out diffraction element is a reflective diffraction element, and a first quarter-wave plate is also disposed between the surfaces of the coupled-out diffraction element and the waveguide element. The polarization selector is a polarization beam splitter; the polarization beam splitter, the waveguide body having the end with the first inclined surface, and the compensation member having the end with the second inclined surface together form a PBS device; The polarizing beam splitter is a film layer that reflects first linearly polarized light and transmits second linearly polarized light. The first linearly polarized light and the second linearly polarized light are orthogonal. The polarization direction of the first linearly polarized light is at a 45° angle to the fast axis direction of the first quarter-wave plate, so that the first linearly polarized light reflected by the polarizing beam splitter is transmitted through the first quarter-wave plate to form first circularly polarized light. The coupled diffraction element is used to reflectively diffract the first circularly polarized light to output a second circularly polarized light; the polarization rotation directions of the first and second circularly polarized lights are opposite.

3. The AR display device as described in claim 2, characterized in that, A light-blocking polarizer is provided on the surface of the coupled diffraction element away from the waveguide element, which is used to transmit the second circularly polarized light and block the first circularly polarized light.

4. The AR display device as described in claim 3, characterized in that, The light-blocking polarizer includes a second quarter-wave plate and a linear polarizer stacked together, which are attached to the surface of the coupled diffraction element on the side away from the first quarter-wave plate. The linear polarizer is a polarizer that blocks the second linearly polarized light and transmits the first linearly polarized light; The fast axis direction of the second quarter-wave plate forms a 45° angle with the polarization direction of the linear polarizer, and is parallel to the fast axis direction of the first quarter-wave plate.

5. The AR display device as described in claim 1, characterized in that, The coupled-out diffraction element is a reflective diffraction element, and a first quarter-wave plate is disposed between the surfaces of the coupled-out diffraction element and the waveguide element; The polarization selector is a polarizing grating capable of reflective diffraction of circularly polarized light.

6. The AR display device according to any one of claims 2 to 5, characterized in that, The first inclined surface and the second inclined surface are inclined curved surfaces with the same surface shape; the polarization selector is a curved polarization element with the same surface shape as the first inclined surface.

7. The AR display device according to any one of claims 2 to 5, characterized in that, A light-transmitting medium layer is disposed between the surface of the first quarter-wave plate and the waveguide element; the refractive index of the light-transmitting medium layer is less than the refractive index of the waveguide element; and the critical angle of the light-transmitting medium layer with respect to the waveguide element is less than the total internal reflection incident angle of the projection beam transmitted through the waveguide element.

8. The AR display device as claimed in claim 1, characterized in that, The coupled-out diffraction element is a transmission diffraction element; The deflecting optical element is a deflecting diffraction element, and the dispersion characteristics of the deflecting diffraction element for different wavelengths are opposite to those of the coupled diffraction element for different wavelengths.

9. The AR display device according to any one of claims 1 to 5 and 8, characterized in that, The projection optical engine includes a projection light source and a shaping element; the shaping element is disposed in the optical path between the projection light source and the coupling end face, and is used to modulate the projection beam output by the projection light source so that the projection beam is coupled into the waveguide element through the coupling end face to form a parallel beam.

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