CN113031279A

CN113031279A - Near-to-eye display device with rectangular exit pupil

Info

Publication number: CN113031279A
Application number: CN202110386716.XA
Authority: CN
Inventors: 程德文; 汪希萌; 陈海龙; 王其为; 倪栋伟
Original assignee: Beijing Ned+ar Display Technology Co ltd
Current assignee: Beijing Ned+ar Display Technology Co ltd
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2021-06-25

Abstract

The invention discloses a near-to-eye display device with a rectangular exit pupil, which comprises an optical lens group and a waveguide system, wherein a micro display is arranged at the coupling end of the waveguide system; the optical lens group is used for receiving image light; the optical lens group comprises a PBS prism, a reflecting mirror and a first lens; the PBS prism comprises a light incidence surface, a light collimation surface and a light emergence surface; the image light enters the PBS prism from the light incidence surface and is emitted from the light collimation surface; a reflecting mirror located at one side of the light collimating surface for reflecting and collimating the image light emitted from the light collimating surface; the image light reflected by the reflector enters the PBS prism again and then is emitted from the light emergent surface; a first lens between the light exit surface and the coupling end of the waveguide system; the image light emitted from the light emitting surface is coupled into the waveguide system after passing through the first lens; the surfaces of the reflecting mirror, the PBS prism, and the first lens perpendicular to the optical axis of the image light are all rectangular.

Description

Near-to-eye display device with rectangular exit pupil

Technical Field

The invention relates to a near-to-eye display device, and belongs to the field of optical display equipment.

Background

As the concept of Virtual Reality (VR) and Augmented Reality (AR) has been proposed, the market of near-eye display devices based on VR or AR modes has also been greatly developed. Among the hardware implementations that apply AR or VR technology, head-Mounted Display (HMD) and Near-Eye Display (NED) are the most efficient implementations that bring the best experience to the user in the prior art.

A near-eye display is a head-mounted display that can project an image directly into the eye of a viewer. The display screen of the NED is very close to human eyes and is smaller than the photopic vision distance, and the human eyes cannot directly distinguish the image content on the display screen. The image can be enlarged to a far distance through the NED optical system and is refocused on the retina of human eyes, so that the picture seen by the human eyes is as if the picture is beyond a few meters, and the display effect of AR and VR technology is achieved.

Since the near-eye display needs to be worn on the head of a person, it is important to have a small size and a good display effect. Waveguide display systems are one of the solutions for realizing near-eye display, but the size and weight of the projection system are too large due to the limitation of the size of the coupling end of the geometric waveguide. Moreover, for a single geometric waveguide, it only has the capability of one-dimensional pupil expansion, so the entrance pupil of the projection system is different from the traditional lens design.

Disclosure of Invention

The invention aims to provide a near-eye display device with a rectangular exit pupil.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a near-eye display device with a rectangular exit pupil comprises optical lens groups and a waveguide system, wherein the optical lens groups are arranged at the coupling end of the waveguide system; wherein the content of the first and second substances,

the optical lens group is used for receiving image light from the micro display;

the optical lens group comprises a PBS prism, a reflecting mirror and a first lens;

the PBS prism comprises a light incidence surface, a light collimation surface and a light emergence surface, and the PBS prism further comprises a polarization selection beam splitter which is positioned on a plane obliquely intersected with the light incidence surface inside the PBS prism; the image light enters the PBS prism from the light incident surface and exits from the light collimating surface;

the reflector is positioned on one side of the light collimation surface and is used for reflecting and collimating the image light emitted from the light collimation surface; the image light reflected by the mirror enters the PBS prism again and exits from the light exit surface;

the first lens located between the light exit surface and the coupling end of the waveguide system; the image light emitted from the light exit surface is coupled into the waveguide system after passing through the first lens;

the reflector, the PBS prism and the first lens are all rectangular in shape on the surfaces perpendicular to the optical axis of the image light.

Wherein preferably, the aspect ratio of the rectangle is greater than 3: 1, wherein, the side perpendicular to the plane formed by the optical axes of the image lights is a long side, and the side parallel to the plane formed by the optical axes of the image lights is a wide side.

Wherein preferably, the aspect ratio of the rectangle is in the range of 6: 1 to 9: 1.

Wherein preferably the light entry surface and the light exit surface are two adjacent surfaces of the PBS prism.

Preferably, the light collimating surface is opposite to the light incident surface or the light collimating surface is opposite to the light exit surface.

Preferably, the optical lens group further comprises a second lens and/or a third lens, the second lens is located between the PBS prism and the reflecting mirror, and the third lens is located between the PBS prism and the microdisplay.

Preferably, the optical lens group further comprises a diaphragm, the diaphragm is arranged at the exit pupil position of the optical lens group, and the diaphragm is used for limiting the rectangular exit pupil shape.

Preferably, the waveguide system comprises a triangular prism and an optical waveguide, and a coupling end of the optical waveguide is coupled with the optical lens group through the triangular prism; the optical lens group is obliquely arranged relative to the optical waveguide, and an included angle between the optical axis of the first lens and the extension line of the optical waveguide is an acute angle.

Preferably, the optical lens group is located on the same side of the extension line of the optical waveguide.

Preferably, the distance between the position, which is closest to the visual axis and is farthest from the optical waveguide, of the optical lens group and the visual axis of the optical waveguide is between 40 and 50 mm.

The near-eye display device provided by the invention comprises an optical lens group and a waveguide system, wherein the coupling end of the waveguide system is sequentially provided with optical elements in the optical lens group; wherein, by using the optical lens group with rectangular exit pupil shape and the waveguide system with one-dimensional pupil expanding capability, a larger eyebox (eye movement area, eye fitting area) is obtained by using the optical lens group with smaller volume. The optical lens group in the near-eye display device has a good imaging effect, and the volume of the optical system can be reduced by adopting the PBS prism; the PBS prism is matched with the reflector for use, so that aberration is further corrected, imaging quality is improved, and popularization and use are easy.

Drawings

Fig. 1 is a schematic structural diagram of a near-eye display device according to a first embodiment of the present invention;

fig. 2 is a schematic structural diagram of an optical lens assembly provided in the first embodiment;

FIG. 3 is a schematic top view of the optical lens assembly shown in FIG. 2;

fig. 4 is a schematic structural diagram of a near-eye display device according to a second embodiment of the present invention;

fig. 5 is a schematic structural diagram of an optical lens assembly provided in the second embodiment.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention provides a near-eye display device which comprises optical lens groups and a waveguide system, wherein the optical lens groups are sequentially arranged at the coupling end of the waveguide system. In the near-eye display device, an optical lens group with a rectangular exit pupil shape is correspondingly designed according to the one-dimensional pupil expanding capability of the optical waveguide system.

In particular, the optical mirror assembly is adapted to receive image light provided by the microdisplay, preferably directly from the microdisplay. After the optical processing is carried out on the image light by the optical lens group, the image light is introduced into the waveguide system and is transmitted to human eyes for display through the waveguide system.

And the optical lens group comprises a PBS prism, a reflecting mirror and at least one lens. Wherein the PBS prism is formed of a light wave transmissive material having a plurality of outer surfaces (including a light entrance surface, a collimating surface, a light exit surface, and other surfaces). The PBS prism also includes a polarization-selective beam splitter disposed within the PBS prism and located on a plane obliquely intersecting the light-entry surface. The polarization selective beam splitter can be implemented by plating a reflective film reflecting light of a specific polarization on the inclined surface inside the PBS prism.

In the following description, the arrangement of the PBS prism, the reflecting mirror, and the at least one lens is described in the optical axis direction of the image light. For ease of understanding, the entire lens group will be described with the image light traveling in a direction parallel to the paper as the viewing angle. However, the above arrangement is only used to illustrate the relative position of each optical element, and is not used to limit the arrangement and application of the lens set. It will be appreciated that in practical applications, the optical lens assembly as a whole may be rotated with respect to the orientation described below.

An image light source (e.g., using a microdisplay) is disposed on one side of the light-incident surface for emitting image light that enters the PBS prisms from the light-incident surface. According to different light path designs, different surfaces of the PBS prism correspondingly become a light emergent surface and a light collimation surface.

The reflector is arranged on one side of the light collimation surface and used for reflecting and collimating the image light emitted from the light collimation surface and eliminating aberration. The image light emitted from the light collimating surface may be p-type polarized light transmitted through the polarization selective beam splitter, or s-type polarized light reflected by the polarization selective beam splitter, depending on the specific optical path design. The mirror may be spherical, aspherical or free-form. Preferably, the mirror has an aspherical surface. The image light reflected by the mirror enters the PBS prism, passes through the PBS prism (which may be transmitted through or reflected by the polarization selective beam splitter), and then exits the light exit surface.

At least one lens is located on a transmission path of the image light. The at least one lens at least comprises the first lens positioned on one side of the light emergent surface of the PBS prism, and the imaging quality of the large-size exit pupil image can be remarkably improved by arranging the first lens. Meanwhile, the first lens is arranged to adjust the focal power of the optical lens group, so that the transmission path of the image light from the PBS prism to the optical waveguide system can be prolonged. On the basis, the other lenses can be arranged on the whole transmission path of the image light according to the requirement of the light path to carry out aberration correction. For example, the at least one lens may further include a second lens positioned between the PBS prism and the mirror and/or a third lens positioned on the side of the light incident surface between the PBS prism and the image light source.

By arranging at least one lens in the optical lens group, the aberration can be eliminated, and the imaging quality is improved. At least one lens may be a single lens, a cemented positive-negative lens, or a lens group formed by sequentially arranging a plurality of lenses. Using cemented positive-negative lenses, the color can be made achromatic. The profile of at least one lens may be spherical or aspherical.

In the above optical lens group, in order to obtain a rectangular exit pupil shape, the surfaces of the optical elements (including the reflecting mirror, the PBS prism, and the first lens) in the optical lens group perpendicular to the optical axis of the image light are all rectangular in shape. The aspect ratio of the rectangle is at least greater than 3: 1. the description of the rectangular exit pupil shape and the shapes of the optical elements in the optical lens assembly will be described in detail in the following embodiments with reference to the accompanying drawings.

The following embodiments provide two exemplary implementations of a near-eye display device, and the optical lens group used in the same is described in detail.

First embodiment

The embodiment provides a near-eye display device suitable for being used by glasses type near-eye display equipment.

For convenience of description, the near-eye display device is shown in fig. 1 in a top view in actual use. The near-eye display device shown in fig. 1 comprises an optical lens group 200 and a waveguide system 400. In fig. 1, also exemplarily showing a microdisplay 100 for providing image light, the microdisplay 100 being located at a side of the light entrance surface 201, the microdisplay 100 may use an OLED, LCOS, LCD type display. The waveguide system 400 is perpendicular to the user's visual axis, and the optical lens assembly 200 and the microdisplay 100 are sequentially arranged at the coupling end of the waveguide system 400. The waveguide system 400 is disposed in the frame, and the microdisplays 100 and the optical lens assembly 200 are disposed at the positions where the frame and the temple are combined.

The structure of the optical lens group used in this embodiment will be described first with reference to fig. 2 and 3.

As shown in fig. 2, the entire optical lens group will be described by taking as an example the case where image light is incident from above and transmitted in a direction parallel to the paper surface, and the optical axes of the image light are all located in a vertical plane, which is denoted as a plane P. The orientation in this embodiment is only used to understand the relative position relationship of each optical element in the optical lens group, and does not limit the actual use position of the entire optical lens group.

The optical lens group provided in this embodiment includes a first lens 21, a PBS prism 22, a reflecting mirror 23, and a second lens 24. Wherein, the image source (specifically, the microdisplay 100) is arranged above the PBS prism 22, and the upper surface of the PBS prism 22 is a light incident surface 221; the right surface of the PBS prism 22 is taken as a light collimation surface 222, and the reflecting mirror 23 is arranged at the right side of the PBS prism 22; the left surface of the PBS prism 22 is a light exit surface 223, and the first lens 21 is disposed on the left side of the PBS prism 22. The second lens 24 is disposed between the image light source 100 and the PBS prism 22.

In the optical mirror group shown in fig. 2, image light emitted from the microdisplay 100 enters the PBS prism 22 from the light entrance surface 221 after passing through the second lens 24, and reaches the polarization-selective beam splitter at the position of the inclined surface 204; the image light reflected by the polarization-selective beam splitter exits from the light collimating surface 222 to reach the mirror 23; the image light reflected by the reflecting mirror 23 enters the PBS prism 22, passes through the polarization selective beam splitter, and exits from the light exit surface 223; then, the optical lens passes through the first lens 21 to reach the exit pupil position.

In the present embodiment, the first lens 21 is formed by positive-negative lens gluing; the lens 211 located on the left side is a positive lens formed of a material having a lower refractive index and a large abbe number than the negative lens; the lens 212 on the right side is a negative lens and is formed of a material having a larger refractive index and a smaller abbe number than the positive lens. The second lens 24 is formed by positive-negative lens gluing; the lens 241 on the lower side is a positive lens formed of a material having a lower refractive index and a large abbe number than the negative lens; the lens 242 located on the upper side is a negative lens and is formed of a material having a larger refractive index and a smaller abbe number than the positive lens. Therefore, the effects of correcting paraxial spherical aberration and reducing chromatic aberration are achieved.

The PBS prism 22 is a polarization splitting prism in which a light collimating surface (i.e., the right surface of the PBS prism 22 in fig. 2) is attached with a polarization-converting polarizer or a polarization-converting film. The reflective surface of the PBS prism 22 (i.e., the inclined surface 204 in the PBS prism 22 in fig. 2) is coated with a reflective film that reflects light of a particular polarization.

In fig. 2, the surfaces of the cemented first lens 21 are, in order from left to right: a front surface 201, a bonding surface 202, and a back surface 203; the tilted surface of PBS prism 22 is surface 204; the reflective surface of mirror 23 is surface 205; the surfaces of the cemented second lens 24, from bottom to top, are: a lower surface 206, an adhesive surface 207, and an upper surface 208. The focal length f of the optical lens group satisfies: 5mm < f <20 mm.

The surface shapes of the first lens 21 and the second lens 24 may be spherical or aspherical. The mirror 23 may be spherical, aspherical or free-form.

Tables 1 and 2 show the design parameters of the optical surfaces of the lenses in the optical lens assembly, wherein the first lens 21 and the second lens 24 are both spherical, and the reflecting surface of the reflecting mirror 23 is aspheric.

TABLE 1 optical surface parameters of various surfaces in the first embodiment

TABLE 2 values of coefficients in the aspherical equation of the reflecting surface 205 of the mirror 23

Wherein, the aspheric equation is:

where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the conic constant, and Ai is the high order term coefficient. The values of the various coefficients of the reflecting surface 205 of the mirror 23 are shown in table 2.

Fig. 3 shows a top view of the optical lens assembly shown in fig. 2, wherein the second lens element 24 is omitted. The image light is transmitted in a plane perpendicular to the paper surface, and at this time, the plane where the optical axis of the image light is located is a plane P perpendicular to the paper surface. With respect to the paper direction, the image light enters the inside of the PBS prism 22 from the light entrance surface 221, exits from the light collimating surface 222 on the right side after being reflected by the surface 204, then enters the inside of the PBS prism 22 again after being reflected by the mirror 23, exits from the light exit surface 223 of the PBS prism 22 through the surface 204, and finally reaches the exit pupil position through the first lens 21.

In the transmission process of the image light, the image light passes through the light incident surface 221, the inclined surface 204, the light collimating surface 222, the surface 205, the light collimating surface 222, the inclined surface 204, the light exiting surface 223, the surface 203, the surface 202, and the surface 201 in this order.

In order to obtain a rectangular exit pupil shape, all surfaces of the image light source 100, the first lens 21, the PBS prism 22, the reflecting mirror 23, and the second lens 24 that are perpendicular to the optical axis of the image light are rectangular in shape. The aspect ratio of the rectangle is at least greater than 3: 1.

as can be seen from the plan view shown in fig. 3, a plane formed by the optical axes of the image lights is taken as a reference plane (i.e., a horizontal plane shown in fig. 3, and the plane P is indicated by a chain line), and among the surfaces perpendicular to the optical axes of the image lights, a side perpendicular to the reference plane P is taken as a long side and a side parallel to the reference plane P is taken as a wide side. Wherein, preferably, the value range of the wide side is not more than 5 mm.

In fig. 3, the shape of the light entrance surface 221 can be seen, taking the light entrance surface 221 as an example, giving a rectangular schematic. Wherein, preferably, the ratio of the long side L to the wide side H is 6: 1-9: 1. It will be appreciated that the PBS prism 22 is a rectangular solid with a smaller cross-section and a longer length. Wherein two side lengths of the cross section respectively correspond to the wide sides H of the light incident surface 221; the length of the PBS prism 22 is equal to the long side L of the light incident surface 221.

Corresponding to the PBS prism 22, in the image shown in fig. 3, the mirror 23 and the first lens 21 have a length in the plane shown in fig. 3, which is close to the length of the PBS prism 22, and a length which can cover all the rays of the image light; the mirror 23 and the first lens 21 have a width close to the side length of the cross section of the PBS prism 22 in the direction perpendicular to the paper surface, and a width that can cover all the rays of the image light.

Preferably, the optical lens group further comprises a diaphragm 26, the diaphragm 26 is disposed at an exit pupil position of the optical lens group, and the diaphragm 26 is used for defining a rectangular exit pupil shape.

Turning back to fig. 1, the structure of the entire near-eye display device will be described.

The waveguide system 400 includes an optical waveguide 401 and a triangular prism 402. The optical waveguide 401 is an array optical waveguide, the optical coupling end of the optical waveguide 401 is a plane obliquely intersecting with the length direction of the optical waveguide, and image light is incident from the optical coupling end, then is totally reflected inside the optical waveguide 401, and is reflected out of the optical waveguide 401 by the plurality of semi-transparent and semi-reflective films. The light incoupling end of the light guide 401 is coupled to the optical lens group 200 through the triangular prism 402, and the light incident surface of the triangular prism 402 is arranged at the exit pupil position of the optical lens group, so as to realize the incoupling of the image light. The optical lens group 200 is disposed obliquely with respect to the optical waveguide 401, and an angle between an optical axis of the first lens 21 and an extension line of the optical waveguide 401 is an acute angle.

In the above structure, the matching angle of the triangular prism 402 can be selected according to the actual requirement of the near-eye display device, so that the whole optical lens group is deflected relative to the optical waveguide 401. At this time, by controlling the vertex angle range of the triangular prism 402 and combining with the focal power control of the optical lens group, the optical lens group can be located on the same side of the extension line of the optical waveguide, and the outline of the outermost side of the optical lens group does not exceed the extension line of the optical waveguide 401.

Specifically, the deflection of the optical mirror group with respect to the optical waveguide 401 is realized by the triangular prism 402; by disposing the light entrance surface 221 and the light exit surface 223 of the PBS prism 22 as adjacent surfaces, the microdisplay 100 is positioned in a region between the PBS prism 22 and the extension line of the light guide 401; the distance between the PBS prism 22 and the optical waveguide system 400 is lengthened by the first lens 21, so that the PBS prism 22 and the microdisplay 100 are farther away from the extension line of the optical waveguide 401, and the optical lens group can be ensured to be located on the same side of the extension line of the optical waveguide 401 as a whole. Preferably, by disposing the second lens 24 between the light incident surface 221 of the PBS prism 22 and the microdisplay 100, the disposition distance of the microdisplay 100 is adjusted so that the profile of the microdisplay 100 does not exceed the extension line of the light guide 401.

Meanwhile, through the arrangement, the distance between the whole optical lens group and the visual center position (namely the visual axis) of the optical waveguide is further increased, and the adaptive distance of the optical lens group is increased. The distance S between the lowest end of the outer contour of the entire optical lens group on the side close to the optical axis of the optical waveguide (i.e. the position of the optical lens group on the side close to the optical axis and farthest from the optical waveguide) and the visual center position of the optical waveguide in fig. 1 is taken as the adaptive distance of the optical lens group, and the distance corresponds to the distance between the glasses legs and the glasses. The preferable value range of the distance S is 40-50 mm, and the distance can meet the use requirement of the near-eye display device in glasses near-eye display equipment.

In the near-eye display device shown in fig. 1, preferably, the distance between the microdisplay 100 and the optical mirror group 200 should be controlled within a small size range.

Second embodiment

The embodiment provides a near-eye display device suitable for being used by a head-mounted near-eye display device.

For convenience of description, the near-eye display device will be described below in terms of a side view angle in actual use. The near-eye display device shown in fig. 4 comprises an optical lens assembly 300 and a waveguide system 400'. Similar to fig. 1, a microdisplay 100 for providing image light is also provided in fig. 4, the microdisplay 100 being positioned at one side of the light incident surface 321, the microdisplay 100 may be an OLED, LCOS, LCD type display. The waveguide system 400 ' is perpendicular to the user's visual axis, and the optical lens assemblies 300 are arranged in sequence at the coupling end of the waveguide system 400 '. Unlike fig. 1, the waveguide system 400 is disposed in front of the eye, and the microdisplay 100 and the optical lens assembly 300 are disposed above the waveguide system 400 at the overhead position.

Preferably, the waveguide system 400 ' includes a light waveguide 401 ' and a triangular prism 402 ', and the light-coupling end of the light waveguide 401 ' is coupled to the exit pupil position of the optical lens group 300 through the triangular prism 402 ', so as to couple in the image light. The optical lens group 300 is disposed obliquely with respect to the optical waveguide 401 ', and an angle between an optical axis of the first lens 31 and an extension line of the optical waveguide 401' is an acute angle.

An optical lens group similar to that shown in fig. 2 and 3 can be used in fig. 4. Since the optical lens group is located at the vertex position, in the near-eye display device, the relationship between the outer contour of the optical lens group and the extension line of the optical waveguide and the visual axis of the optical waveguide is not strictly limited.

Another optical lens group that can be used in this embodiment is described below with reference to fig. 5, wherein the optical lens group 300 is not required to be strictly located on the same side of the extension line of the optical waveguide 401'.

In fig. 5, image light is incident from above (i.e., obliquely above in fig. 4), and the image light is transmitted in a direction parallel to the paper surface. The orientation in fig. 5 is only used for understanding the relative position relationship of the optical elements in the optical lens assembly, and does not limit the actual position of the entire optical lens assembly.

As shown in fig. 5, the optical lens assembly provided in this embodiment includes a first lens 31, a PBS prism 32, a reflector 33, a second lens 34, and a third lens 35. Wherein, the image source (specifically, the microdisplay 100) is arranged above the PBS prism 32, and the upper surface of the PBS prism 32 is a light incident surface 321; the right surface of the PBS prism 32 is taken as a light collimation surface 322, and the reflecting mirror 33 is arranged at the right side of the PBS prism 32; the left surface of the PBS prism 32 is a light exit surface 323, and the first lens 31 is disposed on the left side of the PBS prism 32. Second lens 34 is disposed over PBS prism 34 between PBS prism 34 and image light source 100.

In the present embodiment, unlike the first embodiment, on the right side of the PBS prism 32, a third lens 35 is further provided, and the third lens 35 is disposed between the PBS prism 32 and the reflecting mirror 33. Air gaps are present between the PBS prism 32, the third lens 35, and the mirror 33. In the prior art, a structure exists in which a lens is arranged on one side of the light collimation surface of the PBS prism 32 only, and the surface of one side of the lens, which is far away from the PBS prism, is used as a reflection surface. For this reason, in this embodiment, by providing the third lens 35 and the reflecting mirror 33 at the same time on the light collimating surface side of the PBS prism 32, the reflecting mirror 33 is set to an aspherical surface type, and the above-described problem is overcome.

Wherein the first lens 31 is a positive lens, and the first lens 31 is formed of a material having a lower refractive index and a large abbe number than the negative lens. The second lens 34 is a positive lens formed of a material having a lower refractive index and a large abbe number than the negative lens; therefore, the effects of correcting paraxial spherical aberration and reducing chromatic aberration are achieved. The third lens 35 is a negative lens and is formed of a material having a larger refractive index and a smaller abbe number than the positive lens.

In the optical lens group shown in fig. 5, image light emitted from the image light source 100 enters the PBS prism 32 from the light incident surface 321 after passing through the second lens 34, and reaches the polarization selective beam splitter located at the inclined surface 303; the image light reflected by the polarization-selective beam splitter exits from the light collimating surface 322, passes through the third lens 35, and reaches the mirror 33; the image light reflected by the reflecting mirror 33 passes through the third lens 35 again, passes through the light collimating surface 322, and enters the PBS prism 32; then, the image light passes through the polarization-selective beam splitter, exits from the light exit surface 323, and passes through the first lens 31 to reach the exit pupil position.

In fig. 5, the surface of the first lens 31 is a front surface 301 and a rear surface 302 in the order from left to right, the inclined surface of the PBS prism 32 is a surface 303, the surface of the third lens 35 is a front surface 304 and a rear surface 305 in the order from left to right, the reflecting surface of the reflector 33 is a surface 306, and the surface of the second lens 34 is a lower surface 307 and an upper surface 308 in the order from bottom to top.

The surface shapes of the first lens 31, the second lens 34 and the third lens 35 can be spherical or aspherical. The mirror 33 may be spherical, aspherical, or free-form. Focal length f of the optical lens group: 15mm < f <25 mm.

The present application provides a set of design parameters for each lens in the second embodiment. As shown in table 3, in this design, the surfaces of the first lens 31, the second lens 34, and the third lens 35 are all spherical, and the reflecting surface of the reflecting mirror 33 is aspherical.

TABLE 3 optical surface parameters of various surfaces in the second embodiment

TABLE 4 values of coefficients in the aspherical equation of the reflecting surface 306 of the mirror 33

Wherein the equation for the aspheric surface is:

Similarly, in the second embodiment, in order to obtain a rectangular exit pupil shape, all surfaces perpendicular to the optical axis of the image light among the first lens 31, the PBS prism 32, the reflecting mirror 33, the second lens 34, and the third lens 35 are rectangular in shape. The description of the specific shape of the optical element is the same as that of the first embodiment, and is not repeated herein.

In the near-eye display device shown in fig. 4, depending on the specific structure of the optical waveguide, the human eye can see an image from the left side of the optical waveguide. When the optical waveguide is replaced so that the image is coupled out of the transflective film to the right side, the image can be seen by the human eye from the right side of the optical waveguide.

As can be understood by combining the above two embodiments, in the optical lens group, for the rectangular exit pupil shape, on one hand, by making the surfaces of the optical elements in the optical lens group perpendicular to the optical axis rectangular, the optical elements having a strip shape as a whole are designed; on the other hand, the transmission path of the image light is folded by combining the PBS prism and the reflecting mirror, and an optical lens group with extremely small volume is designed. The optical lens group is particularly suitable for near-eye display equipment of the glasses type.

In addition, in the specific light path design of the optical lens group, the light incident surface and the light emergent surface of the PBS prism are adjacent surfaces, and the first lens is arranged on one side of the light emergent surface, so that the focal power of the whole optical lens group is changed, the arrangement distance between the PBS prism and the optical waveguide system in the optical lens group is increased, the optical lens group with a compact structure is obtained, and the volume of the near-to-eye display device is reduced.

In the above embodiments, the structure of the optical lens group provided in the present application is illustrated by taking the arrangement manner of the light collimating surface adjacent to the light incident surface as an example. The light collimating surface may also be arranged as a surface opposite the light entrance surface, depending on the specific light path design. In this case, a mirror is provided opposite to the image light source, and the image light transmitted through the polarization selective beam splitter is reflected by the mirror, enters the PBS prism, is reflected by the polarization selective beam splitter, and is emitted from the light exit surface. In the transmission process of the image light, the polarization type of the polarized light needs to be converted according to the light path design, and details are not described here.

In summary, the near-eye display device provided by the present invention includes an optical lens assembly and a waveguide system, and by using the optical lens assembly with a rectangular exit pupil to cooperate with the waveguide system, and using the optical lens assembly with a smaller volume, and combining the capability of one-dimensional pupil expansion of the waveguide system, a larger eyebox (eye movement area, eye accommodation area) is obtained, for example: 10 mm. The near-to-eye display device is light in shape, small in size, good in display effect and wide in application range. The optical lens group used by the near-eye display device has a good imaging effect, and the volume of the optical system can be reduced by adopting the PBS prism; the PBS prism is matched with the reflector for use, so that aberration is further corrected, imaging quality is improved, and popularization and use are easy.

The near-eye display device having a rectangular exit pupil according to the present invention has been described in detail above. It will be apparent to those skilled in the art that any obvious modifications thereof can be made without departing from the spirit of the invention, which infringes the patent right of the invention and bears the corresponding legal responsibility.

Claims

1. A near-eye display device with a rectangular exit pupil comprises optical lens groups and a waveguide system, wherein the optical lens groups are arranged at the coupling end of the waveguide system; the method is characterized in that:

the optical lens group is used for receiving image light provided by the micro display;

2. The near-eye display device of claim 1, wherein:

the aspect ratio of the rectangle is more than 3: 1, wherein, the side perpendicular to the plane formed by the optical axes of the image lights is a long side, and the side parallel to the plane formed by the optical axes of the image lights is a wide side.

3. The near-eye display device of claim 2, wherein:

the aspect ratio of the rectangle is 6: 1 to 9: 1.

4. The near-eye display device of claim 1, wherein:

the light entrance surface and the light exit surface are two adjacent surfaces of the PBS prism.

5. The near-eye display device of claim 4, wherein:

the light collimating surface is opposite to the light incident surface, or the light collimating surface is opposite to the light exit surface.

6. The near-eye display device of claim 1, wherein:

the optical lens group further comprises a second lens and/or a third lens, the second lens is located between the PBS prism and the reflecting mirror, and the third lens is located between the PBS prism and the microdisplay.

7. The near-eye display device of claim 1, wherein:

the optical lens group further comprises a diaphragm, the diaphragm is arranged at the exit pupil position of the optical lens group, and the diaphragm is used for limiting the rectangular exit pupil shape.

8. The near-eye display device of claim 1, wherein:

the waveguide system comprises a triangular prism and an optical waveguide, and a coupling end of the optical waveguide is coupled with the optical lens group through the triangular prism; the optical lens group is obliquely arranged relative to the optical waveguide, and an included angle between the optical axis of the first lens and the extension line of the optical waveguide is an acute angle.

9. The near-eye display device of claim 8, wherein:

the optical lens group is positioned on the same side of the extension line of the optical waveguide.

10. The near-eye display device of claim 9, wherein:

the distance between the position, which is closest to the visual axis and is farthest away from the optical waveguide, of the optical lens group and the visual axis of the optical waveguide is 40-50 mm.