AR display device

Abstract

The invention discloses AR display equipment. The AR display equipment comprises a projection light machine and a waveguide element, the coupling-in end of the waveguide element is provided with a coupling-in end face which is obliquely arranged relative to the plane where the waveguide element is located. The coupling-out end of the waveguide element is provided with a coupling-out diffraction element parallel to the plane where the waveguide element is located, and the coupling-out diffraction element has focal power; the coupling-out end of the waveguide element is also provided with a deflection optical element; the projection light machine is used for outputting a projection light beam to the coupling-in end face, so that the projection light beam is transmitted in the waveguide element in a total reflection mode, and after the projection light beam is deflected through the deflection optical element, main light rays are perpendicular to the coupling-out diffraction element and enter the coupling-out diffraction element. And the main light is diffracted and output in the direction perpendicular to the coupling-out diffraction element. According to the AR display device, on the basis of having a large field of view or a refraction correction function, distortion of a projection picture formed by the projection light beam is reduced, and the display effect of the projection picture and the use experience of a user are improved.

Description

Technical Field

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

[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 the use of optical elements with a magnifying field of view to maximize the display device's field of view; these optical elements are typically elements with optical power. For another example, to ensure that users with refractive errors such as myopia or hyperopia can clearly see the projected image output by the display device without the need for corrective glasses, it is often necessary to add optical elements with optical power to the AR display device to correct the wearer's diopter. While these approaches can meet the specific needs of wearers using AR display devices to a certain extent, optical elements with optical power can also easily cause distortion in the projected image, thereby reducing the display quality and the user experience. Summary of the Invention

[0003] The purpose of the present 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 of the AR display device or having a refractive correction function.

[0004] To solve the above technical problems, the present invention provides an AR display device, comprising a projection optical engine and a waveguide element; the coupling-in end of the waveguide element has a coupling-in end face arranged obliquely relative to the plane where the waveguide element is located; the coupling-out end of the waveguide element is provided with a coupling-out diffraction element parallel to the plane where the waveguide element is located, wherein the coupling-out diffraction element has optical power; the coupling-out end of the waveguide element is further provided with a deflection optical element; In which, the projection optical engine is used to output a projection light beam to the coupling-in end face, so that the projection light beam is transmitted by total reflection in the waveguide element, and after the projection light beam is deflected by the deflection optical element, the main light beam is incident on the coupling-out diffraction element perpendicular to the coupling-out diffraction element, and is diffracted by the coupling-out diffraction element and output in a direction in which the main light beam is perpendicular to the coupling-out diffraction element.

[0005] In an optional embodiment of the present application, the waveguide element includes a waveguide body having a first inclined surface and a compensating member having a second inclined surface; the waveguide body and the compensating member are connected to each other through the first inclined surface and the second inclined surface, together forming the waveguide element having a flat plate shape and uniform thickness; The deflecting optical element is disposed 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.

[0006] In an optional embodiment of the present application, the outcoupling diffraction element is a reflective diffraction element, and a first quarter-wave plate is further provided between the outcoupling diffraction element and the surface of the waveguide element; The polarization selector is a polarization beam splitting film; the polarization beam splitting film, the end of the waveguide body having the first inclined surface, and the end of the compensation member having the second inclined surface together form a PBS device; The polarization beam splitting film is a film layer that reflects a first linearly polarized light and transmits a second linearly polarized light, the first linearly polarized light and the second linearly polarized light are orthogonal to each other; and the polarization direction of the first linearly polarized light and the fast axis direction of the first quarter-wave plate form an angle of 45°, so that the first linearly polarized light reflected and output by the polarization beam splitting film is transmitted through the first quarter-wave plate to form a first circularly polarized light; The outcoupling 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 circularly polarized light and the second circularly polarized light are opposite.

[0007] In an optional embodiment of the present application, a light-blocking polarizer is provided on a surface of the outcoupling diffraction element facing away from the waveguide element, for transmitting the second circularly polarized light and shielding the first circularly polarized light.

[0008] In an optional embodiment of the present application, the light-blocking polarizer includes a second quarter-wave plate and a linear polarizer stacked and adhered to a surface of the outcoupling optical element facing away from the first quarter-wave plate; The linear polarizer is a polarizer that blocks the second linear polarized light and transmits the first linear polarized light; The fast axis direction of the second quarter wave plate forms an angle of 45° with the polarization direction of the linear polarizer and is parallel to the fast axis direction of the first quarter wave plate.

[0009] In an optional embodiment of the present application, the outcoupling diffraction element is a reflective diffraction element, and a first quarter-wave plate is provided between the outcoupling diffraction element and the surface of the waveguide element; The polarization selector is a polarizer grating capable of reflectively diffracting circularly polarized light.

[0010] In an optional embodiment of the present application, the first inclined surface and the second inclined surface are inclined curved surfaces with the same surface shape; and the polarization selector is a curved polarization element with the same surface shape as the first inclined surface.

[0011] In an optional embodiment of the present application, a light-transmitting medium layer is provided between the first quarter-wave plate and the surface of the waveguide element; the refractive index of the light-transmitting medium layer is smaller 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 smaller than the total reflection incident angle of the projection light beam during total reflection transmission in the waveguide element.

[0012] In an optional embodiment of the present application, the outcoupling diffraction element is a transmissive 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 the dispersion characteristics of the outcoupling diffraction element for different wavelengths.

[0013] In an optional embodiment of the present application, the projection optical engine includes a projection light source and a shaping element; the shaping element is arranged on the optical path between the projection light source and the coupling end face, and is used to modulate the projection light beam output by the projection light source so that the projection light beam is coupled into the waveguide element through the coupling end face to form a parallel light beam.

[0014] An AR display device provided by the present invention includes a projection optical engine and a waveguide element; the coupling-in end of the waveguide element has a coupling-in end face arranged obliquely relative to the plane where the waveguide element is located; the coupling-out end of the waveguide element is provided with a coupling-out diffraction element parallel to the plane where the waveguide element is located, wherein the coupling-out diffraction element has optical focal length; the coupling-out end of the waveguide element is also provided with a deflection optical element; wherein the projection optical engine is used to output a projection light beam to the coupling-in end face, so that the projection light beam is transmitted by total reflection in the waveguide element, and after the projection light beam is deflected by the deflection optical element, the main light beam is incident on the coupling-out diffraction element perpendicular to the coupling-out diffraction element, and is diffracted by the coupling-out diffraction element and output in a direction in which the main light beam is diffracted perpendicular to the coupling-out diffraction element.

[0015] In the AR display device of the present application, a coupling diffraction element with optical power is provided at the coupling end of the waveguide element, so that the AR display device has a relatively large field of view or has the function of correcting the wearer's refractive error. In addition, a deflection optical element capable of deflecting the transmission direction of the projection light beam transmitted by total reflection in the waveguide element is provided at the coupling end of the waveguide element, so that the projection light beam can be incident on the coupling diffraction element with the main ray perpendicular to the direction of the coupling diffraction element after being deflected by the deflection optical element, and diffracted out from the coupling diffraction element with the main ray perpendicular to the direction of the coupling diffraction element. It can be seen that the projection light beam in the present application is incident on the coupling diffraction element with optical power in a substantially vertical direction, and is diffracted out from the coupling diffraction element in a substantially vertical direction, thereby greatly reducing the dispersion and distortion of the projection light beam caused by the diffraction of the coupling diffraction element, thereby improving the imaging effect of the projection picture formed after the projection light beam is finally coupled out from the waveguide element to a certain extent, which is conducive to improving the user experience of the AR display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of a first optical path structure of an AR display device provided in an embodiment of the present application; Figure 2 A schematic diagram of a second optical path structure of an AR display device provided in an embodiment of the present application; Figure 3 A schematic diagram of a third optical path structure of the AR display device provided in an embodiment of the present application; Figure 4 A schematic diagram of a fourth optical path structure of the AR display device provided in an embodiment of the present application; Figure 5 A schematic diagram of a fifth optical path structure of the AR display device provided in an embodiment of the present application; Figure 6 A schematic diagram of a sixth optical path structure of the AR display device provided in an embodiment of the present application; Figure 7 A schematic diagram of a seventh optical path structure of the AR display device provided in an embodiment of the present application; Figure 8 A schematic diagram of the local optical path structure in the AR display device provided in an embodiment of the present application; Figure 9A schematic diagram of the optical path structure of the light-blocking polarizer provided in an embodiment of the present application; Figure 10 Schematic diagram of the eighth optical path structure of the AR display device provided in an embodiment of the present application; In the accompanying drawings: 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 machine, 21 is a projection light source, 22 is a shaping lens, 23 is a transmission polarizer, 24 is a reflection polarizer, 3 is an outcoupling diffraction element, 41 is a polarization beam splitter, 42 is a polarizer 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 DESCRIPTION

[0018] The core of the present invention is to provide an AR display device that can improve the imaging effect of the projection picture to a certain extent.

[0019] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] like Figures 1 to 10 As shown, Figure 1 A schematic diagram of a first optical path structure of an AR display device provided in an embodiment of the present application; Figure 2 A schematic diagram of a second optical path structure of an AR display device provided in an embodiment of the present application; Figure 3 A schematic diagram of a third optical path structure of the AR display device provided in an embodiment of the present application; Figure 4 A schematic diagram of a fourth optical path structure of the AR display device provided in an embodiment of the present application; Figure 5 A schematic diagram of a fifth optical path structure of the AR display device provided in an embodiment of the present application; Figure 6 A schematic diagram of a sixth optical path structure of the AR display device provided in an embodiment of the present application; Figure 7 A schematic diagram of a seventh optical path structure of the AR display device provided in an embodiment of the present application; Figure 8 A schematic diagram of the local optical path structure in the AR display device provided in an embodiment of the present application; Figure 9 A schematic diagram of the optical path structure of the light-blocking polarizer provided in an embodiment of the present application; Figure 10 This is a schematic diagram of the eighth optical path structure of the AR display device provided in an embodiment of the present application.

[0021] In a specific embodiment of the present application, the AR display device may include: Projection optical engine 20 and waveguide element 10; The coupling-in end of the waveguide element 10 has a coupling-in end face 101 arranged obliquely relative to the plane where the waveguide element 10 is located; the coupling-out end of the waveguide element 10 is provided with a coupling-out diffraction element 3 parallel to the plane where the waveguide element 10 is located, wherein the coupling-out diffraction element 3 has optical power; the coupling-out end of the waveguide element 10 is also provided with a deflection optical element; Among them, the projection optical engine 20 is used to output a projection light beam to the coupling end face 101, so that the projection light beam is transmitted by total reflection in the waveguide element 10, and after the projection light beam is deflected by the deflection optical element, the main light beam is incident on the coupling diffraction element 3 perpendicular to the coupling diffraction element, and is diffracted by the coupling diffraction element 3 and output in the direction of the main light beam perpendicular to the coupling diffraction element 3.

[0022] 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 a light source device for outputting a projection light beam, and the waveguide element 10 can be roughly a transparent flat plate structure, similar to the structure of a spectacle lens, and can also be called a waveguide lens. The projection light beam output by the projection optical engine 20 is coupled into the waveguide element 10 through the coupling end of the waveguide element 10, and after at least one total reflection transmission in the waveguide element 10, it is transmitted to the coupling end of the waveguide element 10, and is coupled out to the human eye through the coupling end of the waveguide element 10, so that the user can view the projection image formed by the projection light beam.

[0023] It is understood that in this application Figure 1 In the subsequent figures, only the schematic diagram of the optical path structure for outputting the projection image to the user's single eye is shown. If the projection image needs to be projected to the user's two eyes, the optical path structures corresponding to the two eyes can be the same and symmetrically set, which is not described in detail in this application.

[0024] The projection light engine 20 in this embodiment may include a projection light source 21 and a shaping element, which is arranged on the optical path between the projection light source 21 and the coupling end face 101, and the shaping element may include at least one optical element selected from the group consisting of a shaping lens 22 and a reflective element, so that the projection light beam output by the projection light source 21 is shaped and modulated by the shaping element and then incident on the waveguide element 10 to form a parallel light beam or a light beam with a relatively small divergence angle.

[0025] In addition, the coupling-in end of the waveguide element 10 in this embodiment has a coupling-in end face 101 that is tilted relative to the plane where the waveguide element 10 is located. That is, the coupling-in end face 101 is an inclined surface at the end of the waveguide element 10. Therefore, the projection light beam can be incident on the waveguide element 10 in a direction perpendicular to the main light beam and the coupling-in end face 101. That is, the projection light beam is incident on the waveguide element 10 at an angle and is transmitted by total reflection within the waveguide element 10.

[0026] In this embodiment, the coupling-in end face 101 on the waveguide element 10 can be an inclined plane, and the inclination angle between the inclined plane and the plane on which the waveguide element 10 is located can be determined based on the total reflection angle of the projection light beam during total internal reflection transmission within the waveguide. As described above, the projection light beam in this embodiment needs to be transmitted within the waveguide element 10 in the form of parallel light. When the coupling-in end face 101 of the waveguide element 10 is an inclined plane, the shaping element can be an optical element that modulates the projection light beam into a parallel light beam. The projection light beam can be perpendicular to the coupling-in end face 101 or incident on the coupling-in end face 101 at a specific angle of incidence. As long as the projection light beam is transmitted through the coupling-in end face 101 and then transmitted through total internal reflection transmission within the waveguide element 10, the requirements are met.

[0027] In addition, the coupling end face 101 on the waveguide element 10 in this embodiment may also be an inclined curved surface; Figure 1 and Figure 3 As shown, the coupling end face 101 can specifically be a convex curved surface inclined toward the side of the waveguide element 10 close to the human eye, or a convex curved surface inclined toward the side of the waveguide element 10 away from the human eye; in this case, 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 at the coupling end of the waveguide element 10, that is, the coupling end face 101 of the waveguide element 10 also has a modulating effect on the divergence angle of the projection light, so that it can cooperate with the shaping element in the projection optical engine 20 to jointly modulate the projection light beam incident on the waveguide element 10 through the coupling end face 101 into a parallel light beam, thereby enabling the projection light beam to be transmitted in the waveguide element 10 as parallel light by total reflection. It can be understood that the coupling end face 101 in the present application can also be a concave surface. In this case, the coupling end of the waveguide element 10 is equivalent to a structure in which an inclined plane and a concave lens are integrally formed, and it also has the function of adjusting the divergence angle of the projection light. The coupling end face 101 of the waveguide element 10 can also cooperate with the shaping lens 22 in the projection optical machine 20, thereby achieving the effect of modulating and shaping the projection light beam.

[0028] It can be understood that in another optional embodiment of the present application, the projection light beam output by the projection light engine 20 is not necessarily transmitted in the form of parallel light through total reflection within the waveguide element 10. The projection light beam can also be a light beam with a relatively small divergence angle that is transmitted through total reflection within 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 light beam.

[0029] On this basis, the outcoupling end of the waveguide element 10 in this embodiment is further provided with an outcoupling diffraction element 3. When the projection light beam is totally reflected in the waveguide element 10 and transmitted to the output end of the waveguide element 10 and incident on the outcoupling diffraction element 3, the outcoupling diffraction element 3 diffracts and couples the projection light beam out, so that the projection light beam is incident on the human eye.

[0030] 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 outcoupling diffraction element 3 in this application can adopt a diffraction element with optical focal length, that is, the divergence angle of the projection light can be modulated; however, the outcoupling diffraction element 3 with optical focal length is often prone to introduce distortion and chromatic aberration into the projection light beam during the process of diffracting and coupling the projection light beam, thereby reducing the imaging effect of the projection picture to a certain extent.

[0031] To this end, in order to reduce the distortion introduced by the outcoupling diffraction element 3 in the diffraction of the projection light beam, a deflecting optical element is further provided at the outcoupling end of the waveguide element 10 in the present application. The deflecting optical element can deflect the transmission direction of the projection light beam transmitted by total reflection in the waveguide element 10. When the projection light beam is a parallel beam in the waveguide element 10, the deflecting optical element can make the projection light beam perpendicular to the outcoupling diffraction element 3. When the projection light beam is a beam with a small divergence angle transmitted in the waveguide element 10, the deflecting optical element can make the main ray of the projection light beam perpendicular to the outcoupling diffraction element 3 and enter the outcoupling diffraction element 3. For the sake of convenience in discussion, the following description will only take the case where the projection light beam is perpendicular to the outcoupling diffraction element 3 as an example.

[0032] It's understood that the optical power of a diffractive element is determined by the quadratic terms of the phase distribution, while higher-order terms (such as the quartic and sextic terms) are the source of aberrations (including distortion). When a light beam is incident perpendicularly on a diffractive element with optical power, the light only travels through a small range of r values (the paraxial region), and the influence of higher-order terms is negligible, especially for monochromatic light, where the distortion approaches zero. However, when light is incident obliquely on a diffractive element with optical power, the contribution of higher-order terms in the phase modulation increases significantly, resulting in greater distortion in the resulting image.

[0033] Therefore, based on the above principle, this application uses a deflection optical element to deflect the transmission direction of the projection light beam, so that the projection light beam can be vertically incident on the outcoupling diffraction element 3, and is also diffracted out in a direction perpendicular to the outcoupling diffraction element 3, thereby greatly reducing the distortion introduced by the outcoupling diffraction element 3 in the process of diffracting the projection light beam, thereby improving the display effect of the projection picture formed by the projection light beam.

[0034] In the AR display device of the present application, the deflection optical element can have a variety of different implementation methods, which will be described below with specific embodiments.

[0035] In an AR display device according to an optional embodiment of the present application, the waveguide element 10 may include: A waveguide body 11 having a first inclined surface and a compensating member 12 having a second inclined surface; the waveguide body 11 and the compensating member 12 are connected to each other through the first inclined surface and the second inclined surface, and together form a flat waveguide element 10 with uniform thickness; The deflecting optical element is disposed 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; The deflecting optical element is a polarization selector or a deflecting diffraction element 43 .

[0036] The waveguide element 10 in this embodiment can be divided into a waveguide body 11 and a compensating member 12. The compensating member 12 is a small light-transmitting structure at the outcoupling end of the waveguide element 10. The dividing interface between the waveguide body 11 and the compensating member 12 is inclined relative to the plane on which 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 compensating member 12. The deflecting optical element is disposed between the first inclined surface and the second inclined surface, which is equivalent to embedding the deflecting optical element inside the outcoupling end of the waveguide element 10. The plane on which the deflecting optical element is located is inclined relative to the plane on which the waveguide element 10 is located. The inclination angle of the deflecting optical element relative to the waveguide element 10 is determined based on the angle of total reflection transmission of the projection light beam within the waveguide element 10.

[0037] On this basis, the deflection optical element in this embodiment can be a polarization selector or a deflection diffraction element 43. It can be understood that the 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 deflects the transmission direction of the projection beam through diffraction.

[0038] In practical applications, the type of deflection optical element can vary based on the type of outcoupling diffraction element 3. For example, when the outcoupling diffraction element 3 is a reflective diffraction element disposed on the surface of the waveguide element 10 facing away from the human eye, the deflection optical element is a polarization selector. Conversely, when the outcoupling diffraction element 3 is a transmissive diffraction element disposed on the surface of the waveguide element 10 facing toward the human eye, the deflection optical element can be a polarization selector or a deflection diffraction element 43 without polarization selection. The following describes various implementations described above using specific embodiments.

[0039] Reference Figure 1 and Figure 3 In an optional embodiment of the present application, the outcoupling diffraction element 3 may be a reflective diffraction element, and a first quarter-wave plate 5 is further provided between the outcoupling diffraction element 3 and the surface of the waveguide element 10; The polarization selector is a polarization beam splitting film 41; the polarization beam splitting film 41, the end of the waveguide body 11 having the first inclined surface, and the end of the compensation member 12 having the second inclined surface together form a PBS device; The polarization beam splitting film 41 is a film layer that reflects the first linear polarized light and transmits the second linear polarized light. The first linear polarized light and the second linear polarized light are orthogonal to each other. The polarization direction of the first linear polarized light and the fast axis direction of the first quarter-wave plate 5 form an angle of 45°, so that the first linear polarized light reflected and output by the polarization beam splitting film 41 is transmitted through the first quarter-wave plate 5 to form the first circularly polarized light. The outcoupling diffraction element 3 is used to reflectively diffract the first circularly polarized light and output a second circularly polarized light; the polarization rotation directions of the first circularly polarized light and the second circularly polarized light are opposite.

[0040] like Figure 1 As shown, this embodiment uses a reflective outcoupling diffraction element 3 as an example. Furthermore, the polarization selector in this embodiment is a polarization beam splitter film 41, disposed between the first inclined surface of the waveguide body 11 and the second inclined surface of the compensating element 12. This polarization beam splitter film 41, along with the wedge-shaped ends connecting the waveguide body 11 and the compensating element 12, together form a device similar to a PBS (polarization beam splitting prism). Of course, the angle between the polarization beam splitter film 41 and the plane of the waveguide element 10 in this embodiment does not necessarily have to be 45°; it should ensure that the projection beam incident on the polarization beam splitter film 41, after reflection, can perpendicularly enter the outcoupling diffraction element 3.

[0041] On this basis, the polarization splitting film 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 forms a 45° angle with the polarization direction of the first linearly polarized light that can be reflected by the polarization splitting film 41. Therefore, in practical applications, when the projection light beam is transmitted by total reflection within the waveguide element 10 to the polarization splitting film 41, the polarization splitting film 41 can reflect the first linearly polarized light in the projection light beam, causing the first linearly polarized light in the projection light beam to be incident perpendicularly to the outcoupling diffraction element 3. Obviously, the first linearly polarized light is first incident on the first quarter-wave plate 5 before being incident on the outcoupling diffraction element 3. Because 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°, the first linearly polarized light can form a first circularly polarized light after being transmitted through the first quarter-wave plate 5; the first circularly polarized light is vertically incident on the outcoupling diffraction element 3, and the outcoupling diffraction element 3 reflectively diffracts the first circularly polarized light and outputs a second circularly polarized light. After the second circularly polarized light is transmitted through the first quarter-wave plate 5, a second linear polarized light orthogonal to the first linear polarized light can be formed. Therefore, the second linear polarized light can be transmitted when passing through the polarization splitting film 41, and finally the second linear polarized light is transmitted through the outcoupling end of the waveguide element 10 and the polarization splitting film 41 and output to the human eye.

[0042] Alternatively, as Figure 4 and Figure 5 As shown, in actual applications, a transmissive polarizer 23 or a reflective polarizer 24 can be built into the projection light engine 20 to modulate the projection light beam output by the projection light source 21 into a first linearly polarized light. The first linearly polarized light is incident on the waveguide element 10 through the shaping element, and is then transmitted by total reflection in the waveguide element 10 before being incident on the polarization beam splitter film 41. Of course, the projection light engine 20 does not necessarily need to be provided with a transmissive polarizer 23 or a reflective polarizer 24. When the projection light beam output by the projection light engine 20 is incident on the polarization beam splitter film 41 in the state of natural light, the polarization beam splitter film 41 can reflect only the first linearly polarized light therein and transmit the rest of the light, and can also couple out the first linearly polarized light output perpendicularly to the diffraction element 3.

[0043] In addition, if Figure 1 As shown, if the first quarter-wave plate 5 provided between the outcoupling diffraction element 3 and the waveguide element 10 is directly attached to the surface of the waveguide element 10, the projection light beam may be incident on the optical interface region to which the first quarter-wave plate 5 is attached during the total reflection transmission process in the waveguide element 10, thereby interfering with the transmission of the projection light beam.

[0044] To this end, in another optional implementation of this embodiment, a light-transmitting medium layer may 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 smaller 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 smaller than the total reflection incident angle of the projection light beam during total reflection transmission in the waveguide element 10; thereby, interference of the first quarter-wave plate 5 with the total reflection transmission of the projection light beam can be avoided.

[0045] In practical applications, the light-transmitting medium layer may 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 may also be a light-transmitting adhesive layer provided between the first quarter-wave plate 5 and the waveguide element 10. The refractive index of the light-transmitting adhesive layer is lower than that of the waveguide element 10, thereby preventing the first quarter-wave plate 5 from interfering with the total internal reflection transmission of the projection light beam and also serving as an adhesive layer connecting the first quarter-wave plate 5 and the waveguide element 10.

[0046] Based on the above discussion, this embodiment further takes into account that the diffraction efficiency of the outcoupling diffraction element 3 is difficult to reach 100% for the first circularly polarized light, and the first circularly polarized light that is not diffracted continues to propagate along the original direction, causing light leakage; light leakage may cause the projection image output by the AR display device to be viewed by people other than the wearer, which not only affects the aesthetics but also poses a risk of privacy leakage.

[0047] For this reason, Figure 7 and Figure 8 As shown, in another optional embodiment of the present application, a light-blocking polarizer 6 is further provided on the surface of the outcoupling diffraction element 3 facing away from the waveguide element 10, and the light-blocking polarizer 6 is used to transmit the second circularly polarized light and block the first circularly polarized light.

[0048] Therefore, if Figure 8 As described above, when the first circularly polarized light is vertically incident on the out-coupling diffraction element 3, most of the first circularly polarized light forms the second circularly polarized light after reflective diffraction by the out-coupling diffraction element 3 and is incident on the first quarter-wave plate 5, while a small portion of the first circularly polarized light is incident on the light-blocking polarizer 6 after being transmitted through the out-coupling diffraction element 3, and is blocked by the light-blocking polarizer 6 to avoid light leakage. On this basis, the second circularly polarized light in the ambient light can be transmitted through the light-blocking polarizer 6 and the out-coupling diffraction element 3 in sequence, and after forming the second linearly polarized light through the first quarter-wave plate 5, it can also be incident on the human eye through the transmission of the waveguide element 10. It can be seen that the light-blocking polarizer 6 in this embodiment can not only avoid light leakage of the projection beam, but also avoid complete blocking of the light in the environment, effectively ensuring the display effect of the AR display device.

[0049] Further as Figure 9As shown, the light-blocking polarizer 6 may include a second quarter-wave plate 61 and a linear polarizer 62 stacked and bonded to the surface of the out-coupling optical element facing away from the first quarter-wave plate 5; The linear polarizer 62 is a polarizer that blocks the second linear polarized light and transmits the first linear polarized light; The fast axis direction of the second quarter wave plate 61 forms an angle of 45° with the polarization direction of the linear polarizer 62 , and is perpendicular to the fast axis direction of the first quarter wave plate 5 .

[0050] like Figure 9 As shown, the first circularly polarized light transmitted from the outcoupling diffraction element 3 is incident on the second quarter-wave plate 61, and can form the second linearly polarized light after passing through the second quarter-wave plate 61; and the linear polarizer 62 arranged in contact with the second quarter-wave plate 61 blocks the second linearly polarized light, thereby avoiding the leakage problem of the second linearly polarized light.

[0051] 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, and then formed into a second circularly polarized light after being transmitted through the second quarter-wave plate 61. The second circularly polarized light can then be transmitted through the outcoupling diffraction element 3 and the waveguide element 10 and incident on the human eye, thereby ensuring that the wearer can see the ambient light.

[0052] In the above embodiment, the outcoupling diffraction element 3 is an element that can diffract circularly polarized light. However, in practical applications, the outcoupling diffraction element 3 may also be an element that can diffract linearly polarized light.

[0053] Therefore, if Figure 3 As shown, in another optional embodiment of the present application, the outcoupling diffraction element 3 can be a diffraction element that performs reflective diffraction on the first linearly polarized light and outputs the second linearly polarized light. In this case, the polarization splitting film 41 is a film layer that reflects the first linearly polarized light and transmits the second linearly polarized light. In this case, there is no need to dispose the first quarter-wave plate 5 between the outcoupling diffraction element 3 and the waveguide element 10.

[0054] Therefore, in this embodiment, the projection light beam is transmitted by total reflection in the waveguide element 10 and incident on the polarization beam splitter film 41. The polarization beam splitter film 41 reflects the first linear polarized light in the projection light beam, so that the first linear polarized light is vertically incident on the outcoupling diffraction element 3. The outcoupling diffraction element 3 reflectively diffracts the first linear polarized light and outputs a second linear polarized light. The second linear polarized light is incident on the human eye after passing through the polarization beam splitter film 41 and the waveguide element 10.

[0055] Furthermore, to prevent some of the first linearly polarized light from leaking through the outcoupling diffraction element 3, a linear polarizer 62 can be disposed on the side of the outcoupling diffraction element 3 facing away from the waveguide element 10. This linear polarizer 62 blocks the first linearly polarized light while transmitting the second linearly polarized light. Furthermore, 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 outcoupling diffraction element 3 and the waveguide element 10 to prevent the outcoupling diffraction element 3 from interfering with the total internal reflection of the projection beam.

[0056] Based on the above discussion, when the deflection optical element in the present application is a polarization selector, the polarization selector is not limited to using the polarization splitting film 41.

[0057] like Figure 4 As shown, in another optional embodiment of the present application, the polarization selector can also be a polarizer grating 42, which can reflectively diffract circularly polarized light; the out-coupling diffraction element 3 is a reflective diffraction element, and a first quarter-wave plate 5 is arranged between the out-coupling diffraction element 3 and the surface of the waveguide element 10.

[0058] In this embodiment, the polarizer grating 42 is a grating element capable of reflectively diffracting circularly polarized light. Specifically, it can be a grating element that reflectively diffracts the first circularly polarized light and transmits the second circularly polarized light. The polarization rotation directions of the first and second circularly polarized light are opposite. The outcoupling diffraction element 3 is a diffraction element that reflectively diffracts the second linearly polarized light and outputs the second linearly polarized light. Thus, when the projection beam is totally reflected within the waveguide element 10 and incident on the polarizer grating 42, the polarizer grating 42 can reflectively diffract the first circularly polarized light in the projection beam and output the second circularly polarized light. The second circularly polarized light is transmitted through the first quarter-wave plate 5 and converted into the second linearly polarized light. The second linearly polarized light is perpendicularly incident on the outcoupling diffraction element 3 and reflectively diffracts, and the second linearly polarized light is output perpendicularly. The second linearly polarized light is again transmitted through the first quarter-wave plate 5 and converted back into the second circularly polarized light. After transmitting through the polarizer grating 42 and the waveguide element 10, the second circularly polarized light can enter the human eye.

[0059] like Figure 3 and Figure 5As shown, when the outcoupling diffraction element 3 is a reflective diffraction element, the polarization selector in this application, whether it is the polarization splitting film 41 or the polarizer 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 outcoupling diffraction element 3 can be a diffraction element that reflectively diffracts the first linearly polarized light and outputs the second linearly polarized light. In this case, there is no need to dispose the first quarter-wave plate 5 between the outcoupling diffraction element 3 and the waveguide element 10. When the projection light beam is transmitted by total reflection in the waveguide element 10 and incident on the polarization selector (which can be the polarization splitting film 41 or the polarizer grating 42), the polarization selector can reflectively diffract the first linearly polarized light in the projection light beam, causing it to be perpendicularly incident on the outcoupling diffraction element 3. The outcoupling diffraction element 3 then reflectively diffracts the first linearly polarized light and outputs the second linearly polarized light. The second linearly polarized light is then transmitted through the polarization selector and the waveguide element 10 and then incident on the human eye.

[0060] Based on any of the above embodiments, regardless of whether the polarization selector is a polarization beam splitter film 41 or a polarizer grating 42, as shown in the figure, the first inclined surface and the second inclined surface interconnecting the waveguide body 11 and the compensator 12 can be inclined curved surfaces with the same surface shape; accordingly, the polarization selector is a curved polarization element with the same surface shape as the first inclined surface and the second inclined surface. In this case, the end of the waveguide body 11 near the compensator 12 is equivalent to a convex lens or concave lens structure with respect to the projection beam, thereby modulating the divergence angle of the projection beam to a certain extent and correcting the distortion of the projection beam, thereby improving the final imaging effect of the projection beam to a certain extent.

[0061] The above embodiments are described using the out-coupling diffraction element 3 as a reflective diffraction element as an example. In practical applications, the out-coupling diffraction element 3 in this application can also be a transmissive diffraction element arranged on the surface of the waveguide element 10 close to the human eye.

[0062] like Figure 2 and Figure 10 As shown, in an optional embodiment of the present application, the outcoupling diffraction element 3 is a transmissive diffraction element; Correspondingly, 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 the dispersion characteristics of the outcoupling diffraction element 3 for different wavelengths.

[0063] like Figure 2 As shown, the deflection diffraction element 43 in this embodiment can be a transmission diffraction element, such as Figure 10As shown, the deflection diffraction element 43 in this embodiment can also be a reflective diffraction element. In short, as long as the projection light beam incident on the deflection diffraction element 43 is diffracted, it can be vertically incident on the out-coupling diffraction element 3, and output to the human eye in a direction perpendicular to the out-coupling diffraction element 3 after being transmitted and diffracted by the out-coupling diffraction element 3.

[0064] Furthermore, as described above, the outcoupling diffraction element 3, with its optical power, has a good distortion reduction effect on the vertically incident projection beam, and particularly has a better distortion correction effect on light of the same wavelength. Therefore, the deflecting diffraction element 43 in this embodiment specifically diffracts light of different wavelengths to produce dispersion characteristics that are opposite to the dispersion characteristics produced by the outcoupling diffraction element 3 when diffracting light of different wavelengths. For example, under the same incident angle, the diffraction angles output by the outcoupling diffraction element 3 for the three different colored light rays increase in sequence; while under the same incident angle, the diffraction angles output by the deflecting diffraction element 43 for the three different colored light rays decrease in sequence. This allows the outcoupling diffraction element 3 and the deflecting diffraction element 43 to achieve complementary dispersion of light of different wavelengths in the projection beam when diffracting the projection beam, thereby further enhancing the display effect formed by the projection beam.

[0065] It can be understood that when the out-coupling diffraction element 3 is a transmissive diffraction element, the deflection optical element in this embodiment can also adopt a polarizer grating 42, and then only diffract the light of a specific polarization direction in the projection light beam to be incident on the out-coupling diffraction element 3. As long as at least part of the light in the projection light beam is vertically incident on the out-coupling diffraction element 3, and is transmitted and diffracted through the out-coupling diffraction element 3 and output vertically to the human eye, there is no specific restriction on this in this application.

[0066] In summary, in the AR display device of the present application, a coupling-out diffraction element with optical focal length is provided at the coupling-out end of the waveguide element, so that the AR display device has a relatively large field of view or has the function of correcting the wearer's refractive error. In addition, a deflection optical element capable of deflecting the transmission direction of the projection light beam transmitted by total reflection in the waveguide element is provided at the coupling-out end of the waveguide element, so that the projection light beam can be deflected by the deflection optical element and then incident on the coupling-out diffraction element with the main ray perpendicular to the direction of the coupling-out diffraction element, and diffracted out from the coupling-out diffraction element with the main ray perpendicular to the direction of the coupling-out diffraction element. It can be seen that the projection light beam in the present application is incident on the coupling-out diffraction element with optical focal length in a substantially vertical direction, and is diffracted out from the coupling-out diffraction element in a substantially vertical direction, thereby greatly reducing the dispersion and distortion of the projection light beam caused by the diffraction of the coupling-out diffraction element, thereby improving the imaging effect of the projection picture formed after the projection light beam is finally coupled out from the waveguide element to a certain extent, which is conducive to improving the user experience of the AR display device.

[0067] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements are inherent to the elements. In the absence of further restrictions, the elements limited by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are not described in detail in accordance with the corresponding technical solutions in the prior art to achieve the same principle, so as to avoid excessive elaboration.

[0068] The principles and implementation methods of the present invention are described herein using specific examples. The description of the above examples is only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. An AR display device, characterized in that: The invention comprises a projection optical engine and a waveguide element; the coupling end of the waveguide element has a coupling end face arranged obliquely relative to the plane where the waveguide element is located; the coupling end of the waveguide element is provided with a coupling diffraction element parallel to the plane where the waveguide element is located, wherein the coupling diffraction element has optical power; the coupling end of the waveguide element is also provided with a deflection optical element; In which, the projection optical engine is used to output a projection light beam to the coupling-in end face, so that the projection light beam is transmitted by total reflection in the waveguide element, and after the projection light beam is deflected by the deflection optical element, the main light beam is incident on the coupling-out diffraction element perpendicular to the coupling-out diffraction element, and is diffracted by the coupling-out diffraction element and output in a direction in which the main light beam is perpendicular to the coupling-out diffraction element.

2. The AR display device according to claim 1, wherein: The waveguide element includes a waveguide body having a first inclined surface and a compensating member having a second inclined surface; the waveguide body and the compensating member are interconnected via the first inclined surface and the second inclined surface, thereby forming the waveguide element having a flat plate shape and uniform thickness; the deflecting optical element is disposed 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 of the waveguide element; The deflecting optical element is a polarization selector or a deflecting diffraction element.

3. The AR display device according to claim 2, wherein: The out-coupling diffraction element is a reflective diffraction element, and a first quarter-wave plate is further provided between the out-coupling diffraction element and the surface of the waveguide element; The polarization selector is a polarization beam splitting film; the polarization beam splitting film, the end of the waveguide body having the first inclined surface, and the end of the compensation member having the second inclined surface together form a PBS device; The polarization beam splitting film is a film layer that reflects a first linearly polarized light and transmits a second linearly polarized light, the first linearly polarized light and the second linearly polarized light are orthogonal to each other; and the polarization direction of the first linearly polarized light and the fast axis direction of the first quarter-wave plate form an angle of 45°, so that the first linearly polarized light reflected and output by the polarization beam splitting film is transmitted through the first quarter-wave plate to form a first circularly polarized light; The outcoupling 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 circularly polarized light and the second circularly polarized light are opposite.

4. The AR display device according to claim 3, wherein: A light-blocking polarizer is provided on the surface of the outcoupling diffraction element on a side facing away from the waveguide element, which is used to transmit the second circularly polarized light and block the first circularly polarized light.

5. The AR display device according to claim 4, wherein: The light-blocking polarizer comprises a second quarter-wave plate and a linear polarizer stacked and attached to the surface of the outcoupling optical element facing away from the first quarter-wave plate; The linear polarizer is a polarizer that blocks the second linear polarized light and transmits the first linear polarized light; The fast axis direction of the second quarter wave plate forms an angle of 45° with the polarization direction of the linear polarizer and is parallel to the fast axis direction of the first quarter wave plate.

6. The AR display device according to claim 2, wherein: The outcoupling diffraction element is a reflective diffraction element, and a first quarter wave plate is provided between the outcoupling diffraction element and the surface of the waveguide element; The polarization selector is a polarizer grating capable of reflectively diffracting circularly polarized light.

7. The AR display device according to any one of claims 3 to 6, wherein: The first inclined surface and the second inclined surface are inclined curved surfaces with the same surface shape; the polarization selector is a curved surface polarization element with the same surface shape as the first inclined surface.

8. The AR display device according to any one of claims 3 to 6, wherein: A light-transmitting medium layer is provided between the first quarter-wave plate and the surface of the waveguide element; the refractive index of the light-transmitting medium layer is smaller 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 smaller than the total reflection incident angle of the projection light beam during total reflection transmission in the waveguide element.

9. The AR display device according to claim 2, wherein: The outcoupling diffraction element is a transmissive 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 the dispersion characteristics of the outcoupling diffraction element for different wavelengths.

10. The AR display device according to any one of claims 1 to 6 and 9, wherein: The projection optical engine includes a projection light source and a shaping element; the shaping element is arranged on the optical path between the projection light source and the coupling end face, and is used to modulate the projection light beam output by the projection light source so that the projection light beam is coupled into the waveguide element through the coupling end face to form a parallel light beam.

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