CN113885212A

CN113885212A - Pupil expanding device

Info

Publication number: CN113885212A
Application number: CN202111324166.5A
Authority: CN
Inventors: 顾志远; 赵鑫; 郑昱
Original assignee: Journey Technology Ltd
Current assignee: Journey Technology Ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2022-01-04
Anticipated expiration: 2041-11-10
Also published as: CN113885212B

Abstract

The invention discloses a pupil expanding device, wherein a second structure subsection is added in an upper waveguide structure of a two-dimensional waveguide sheet in the prior art, an entrance pupil light beam is split into a left field and a right field after being expanded in the horizontal direction for one time, and then is emitted from the lower waveguide structure after being expanded in the horizontal direction, so that the light beam realizes secondary pupil expansion in the horizontal direction in the upper waveguide structure, the lower waveguide structure performs pupil expansion in the vertical direction, and under the condition of adopting common low-refractive-index materials, the field angle, the eye box and the exit pupil distance can be kept unchanged, the size of the two-dimensional waveguide sheet is effectively reduced, the image display of the full field is realized, the device is more suitable for the optimal position of human vision, the machining difficulty is reduced, and the light energy utilization rate is improved.

Description

Pupil expanding device

Technical Field

The embodiment of the invention relates to the technical field of display, in particular to a pupil expanding device.

Background

Augmented Reality (AR) technology is a technology that skillfully fuses virtual information and the real world, and can be used in the real world after simulating virtual information such as characters, images, three-dimensional models, music, videos and the like generated by a computer, so as to supplement the real information in the real world and realize the 'enhancement' of the real world. The head-mounted display utilizing the augmented reality technology can enable people to project virtual images to human eyes while looking up the surrounding environment, and has important significance in the fields of military affairs, industry, entertainment, medical treatment, transportation and the like.

In transmissive head-mounted displays currently used for augmented reality, the main technologies include: the Birdbath, prism, free form surface and optical waveguide technology, compared with other technologies, the head-mounted display adopting the optical waveguide technology has smaller volume and is more like a pair of glasses. The optical waveguide technology mainly includes an array optical waveguide, a surface relief grating waveguide and a volume holographic waveguide, wherein the color expression and the light energy utilization rate of the array optical waveguide are superior to those of a diffraction optical waveguide and a volume holographic waveguide, and particularly, the array optical waveguide adopting the two-dimensional exit pupil expansion technology has the advantages of small coupled light machine volume, large exit pupil distance, large eye box and the like.

As people demand more and more for immersive experiences and the appearance of AR glasses, technicians need to increase the field angle of the display system and also require the display system to be similar in shape and volume to ordinary glasses. Due to the asymmetry of the existing two-dimensional exit pupil expansion technology, if a common material with a lower refractive index (for example, H-BAK5, n is 1.56) is used to transmit a larger field angle (for example, a diagonal line of 55 °), the volume of the two-dimensional waveguide sheet will increase, and the deviation between the effective display area center and the optimal position of human eyes is larger; if a material with a high refractive index is used, the processing difficulty and cost of the two-dimensional waveguide sheet will be greatly increased, the asymmetry of the structure of the two-dimensional waveguide sheet cannot be changed, and the two-dimensional waveguide sheet also faces the problem of volume increase when a larger field angle is transmitted.

Disclosure of Invention

In view of this, embodiments of the present invention provide a pupil expanding device, in which a second structural part is added in an upper waveguide structure of a two-dimensional waveguide sheet in the prior art, an entrance pupil light beam is split into left and right view fields after being expanded in a horizontal direction for one time, and then the light beam reaches a lower waveguide structure after being expanded in the horizontal direction for emergence, so that the light beam realizes secondary pupil expansion in the horizontal direction in the upper waveguide structure, and the lower waveguide structure performs vertical pupil expansion.

In a first aspect, an embodiment of the present invention provides a pupil expanding device, including a first plane, a second plane, and a first waveguide structure and a second waveguide structure, which are disposed between the first plane and the second plane, and sequentially disposed along a first direction; the first waveguide structure comprises a first structure subsection, a second structure subsection and a third structure subsection which are arranged in sequence along a second direction, and the first direction is parallel to the first plane; the second direction intersects the first direction;

the second structure subsection comprises a plurality of second beam splitters and a plurality of second beam splitters, wherein the plurality of second beam splitters are sequentially arranged along a third direction, the plurality of second beam splitters extend along a fourth direction, the plurality of second beam splitters are sequentially arranged along the fourth direction, the plurality of second beam splitters extend along the third direction, and the first direction, the second direction, the third direction and the fourth direction are intersected in pairs;

after a part of light rays entering the second structure subsection pass through a plurality of second beam splitters to realize a first pupil expansion, the part of light rays sequentially enter the first structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion;

and the other part of light rays entering the second structure subsection realize a first pupil expansion through the second beam splitters and then sequentially enter the third structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion.

Optionally, the first structural part includes a plurality of first beam splitters, the plurality of first beam splitters are sequentially arranged in parallel along the second direction, and the plurality of first beam splitters extend along the fourth direction.

Optionally, the third structural subsection includes a plurality of third beam splitters, the plurality of third beam splitters are sequentially arranged in parallel along the second direction, and the plurality of third beam splitters extend along the third direction.

Optionally, the first structural subsection and the third structural subsection are symmetrically disposed along the first direction.

Optionally, the second waveguide structure includes a plurality of fourth beam splitters, and the plurality of fourth beam splitters are sequentially arranged in parallel along the first direction.

Optionally, the plurality of first beam splitters are sequentially arranged in parallel at equal intervals along the second direction;

the third beam splitters are arranged in parallel at equal intervals along the second direction in sequence;

the fourth beam splitters are sequentially arranged in parallel at equal intervals along the first direction.

Optionally, the second beam splitter and the second beam splitter are symmetrically arranged along the first direction.

Optionally, a plurality of the second beam splitters are arranged at equal intervals; the second beam splitters are arranged at equal intervals.

Optionally, an included angle between the fourth direction and the first direction is α, and an included angle between a normal direction of the second beam splitter and a normal direction of the first plane is γ; an included angle between the third direction and the first direction is beta, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma; the angle between the third direction and the fourth direction is 180 ° - (α + β);

an included angle between the normal direction of the fourth beam splitter and the normal direction of the first plane is theta;

wherein alpha is more than 0 and less than 90 degrees, beta is more than 0 and less than 90 degrees, gamma is more than 80 degrees and less than 90 degrees, and theta is more than 20 and less than 28 degrees.

Optionally, the pupil expanding device further comprises a coupling-in structure;

the coupling-in structure comprises a triangular prism and is used for coupling parallel light beams emitted by the light machine into the second structure subsection.

The pupil expanding device provided by the embodiment of the invention comprises a first waveguide structure and a second waveguide structure which are sequentially arranged along a first direction, wherein a second structure subsection is added to the first waveguide structure, and the second structure subsection comprises a plurality of second beam splitters and a plurality of second beam splitters. The second beam splitters are sequentially arranged along a third direction and extend along a fourth direction, and the second beam splitters are sequentially arranged along the fourth direction and extend along the third direction. And after a part of light rays entering the second structure subsection pass through the plurality of second beam splitters to realize a first pupil expansion, the part of light rays sequentially enter the first structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion. And the other part of light rays entering the second structure subsection realize a first pupil expansion through the second beam splitters and then sequentially enter the third structure subsection and the second waveguide structure to complete a second pupil expansion and a third pupil expansion. Under the unchangeable condition in angle of vision, eye box and exit pupil distance, can effectively reduce the size of two-dimensional waveguide piece through the pupil expanding device of this application, realize the image display of full visual field, be fit for people's eye vision best position more, reduce the machining degree of difficulty simultaneously, improved light energy utilization.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:

FIG. 1 is a three-dimensional view of a conventional two-dimensional waveguide sheet structure of the prior art;

FIG. 2 is a diagram of a light path from a point A 'to a point B' in a conventional two-dimensional waveguide structure according to the prior art;

FIG. 3 is an equivalent optical path diagram of a light ray in a general two-dimensional waveguide structure in the prior art;

FIG. 4 is a schematic diagram of a conventional two-dimensional waveguide structure with a diagonal viewing angle of 55 degrees in the prior art;

figure 5 is a schematic structural diagram of a triple pupil expansion device according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a second structural subsection;

FIG. 7 is a schematic structural view of a second alternative structural subsection provided in accordance with an embodiment of the present invention;

figure 8 is a schematic optical path diagram of a triple pupil expansion device according to an embodiment of the present invention;

figure 9 is a left field optical path view of a pupil expansion device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be fully described by the detailed description with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, not all embodiments, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without inventive efforts fall within the scope of the present invention.

Examples

FIG. 1 shows three views of a conventional two-dimensional waveguide sheet; FIG. 2 is a diagram of a light path from a point A 'to a point B' in a conventional two-dimensional waveguide structure according to the prior art; FIG. 3 is an equivalent optical path diagram of a light ray in a general two-dimensional waveguide structure in the prior art; fig. 4 is a shape diagram of a conventional two-dimensional waveguide structure with a diagonal field angle of 55 ° in the prior art. As shown in fig. 1 to 4, a structure of a general two-dimensional waveguide sheet includes an upper structure waveguide sheet and a lower structure waveguide sheet; the upper structure waveguide sheet comprises two

surfaces

1 and 2 which are parallel to each other, and a series of parallel beam splitters 1 are embedded in the

surfaces

1 and 2, the structure mainly has the function of turning light beams coupled into the structure to exit, and each beam splitter can form a primary image for the exit pupil, so that the horizontal pupil expansion is realized; the lower structure waveguide plate is similar to a common one-dimensional array waveguide, and comprises two mutually

parallel surfaces

3 and 4, and a series of parallel beam splitters 2 embedded in the

surfaces

3 and 4, and the main function of the structure is to couple out the light beams which are bent by the upper structure waveguide plate, so that the light beams are received by human eyes and the pupil expansion in the vertical direction is realized. Wherein, surface 1 and surface 3, surface 2 and surface 4 are the coplanar, the existing two-dimensional waveguide slice has the volume and weight to be great, the actual position of human eye and the best position deviation of human eye are great, the problem of the light energy utilization rate is lower, combine fig. 1-4, analyze as follows:

fig. 2(a) shows a light path diagram of a light ray transmitted from a point a 'to a point B' in the upper structured waveguide sheet, and fig. 2(B) shows a light path diagram of a light ray transmitted from a point a 'to a point B' on the surface of the upper structured waveguide sheet, wherein the path length traveled by the light ray in the waveguide sheet is 2L, the path length traveled by the light ray on the surface of the waveguide sheet is D, and the incident angle of the light ray is α, as can be seen from the geometrical relationship in the figure, the following formula 1.1 is satisfied:

D＝2L*sinα， (1.1)；

according to the formula 1.1, it can be understood that the waveguide sheet with the width D has an equivalent length or spread length D/sin α for the light with the incident angle α, and therefore, the separation distance of the beam splitter is D, the incident angle of the light is α, and the equivalent separation or spread interval is D/sin α.

Taking the ordinary two-dimensional waveguide sheet shown in fig. 1 as an example, assuming that the mirror spacing d is sufficiently small, referring to fig. 3, fig. 3 shows an equivalent optical path diagram, in which the inclination angle of the beam splitter 1 to the X direction (i.e., the horizontal direction) is 45 °, the thickness H of the two-dimensional waveguide sheet is 1.7mm, the glass material is H-BAK5 (refractive index n is 1.56), the diagonal field angle of the coupled-in image in the waveguide sheet is 55 ° (16: 9 screen is used, the horizontal field × the longitudinal field is 48.8 ° × 28.63 °), the exit pupil of the coupled-in optical machine is 5.5mm, the exit pupil distance is 20mm, and the horizontal eye box is 10 mm. According to the given parameters, the critical angle alpha of total reflection can be obtained_cSatisfies formula 1.2:

considering the assembly tolerance and the distortion of the optical machine, the minimum incident angle in the two-dimensional waveguide sheet should be slightly larger than the critical angle of 39.87 °, so the total reflection transmission angle of the light in the two-dimensional waveguide sheet is in the range of (40.88 °, 61.92 °), and the central incident angle is 50 °. Combining with the formula (1.1), the equivalent length or the expansion length of the light ray in the lower structural waveguide plate is about 21.12mm, and combining the obtained data, the equivalent height of the upper structural waveguide plate is about 28.98mm and the equivalent length is about 65.9mm can be obtained by using the principle that the light path is reversible, as shown in fig. 3, the actual size of the upper structural waveguide plate is about 50.48mm × 22.2mm by reverse pushing according to the formula (1.1). For example, 6 reflectors 2 are embedded in the lower structured waveguide sheet, and the height of the lower structured waveguide sheet is at least 23mm in consideration of the processing technology according to the design concept of the common one-dimensional waveguide sheet.

From the above analysis, referring to fig. 4, fig. 4 shows the structural shape of a general two-dimensional waveguide sheet with a diagonal field angle of 55 °. It can be seen that the deviation between the actual position of the human eye and the optimal position of the human eye is large in the structure, the actual position of the human eye is probably positioned at the position of the waveguide sheet 3, the redundancy is too much, and the knot 4 of the common two-dimensional waveguide sheet is too much

The structure not only increases the volume and the weight of the two-dimensional waveguide piece, but also reduces the light energy utilization rate.

In view of the above problems, embodiments of the present invention provide a pupil expanding device, which can perform secondary pupil expansion in the horizontal direction and primary pupil expansion in the vertical direction. Figure 5 is a three-view diagram of a pupil expansion device configuration according to an embodiment of the present invention; fig. 8 is a schematic optical path diagram of a triple pupil expansion device according to an embodiment of the present invention. As shown in fig. 5 and 8, the pupil expanding device provided by the embodiment of the invention includes a first plane S1, a second plane S2, and a first waveguide structure 1 and a second waveguide structure 2 disposed between the first plane S1 and the second plane S2, wherein the first waveguide structure 1 and the second waveguide structure 2 are sequentially disposed along a first direction (as shown in the Y direction in fig. 3); the first waveguide structure 1 comprises a first structural branch 11, a second structural branch 12 and a third structural branch 13 arranged in succession along a second direction (indicated as X-direction in fig. 3), the first direction being parallel to a first plane S1 and the second direction intersecting the first direction;

the second structural unit 12 includes a plurality of second beam splitters 121 and a plurality of second beam splitters 122, wherein the plurality of second beam splitters 121 are sequentially arranged along a third direction (e.g., Z direction in fig. 5), the plurality of second beam splitters 121 extend along a fourth direction (e.g., P direction in fig. 5), the plurality of second beam splitters 122 are sequentially arranged along a fourth direction, the plurality of second beam splitters 122 extend along the third direction, and the first direction, the second direction, the third direction, and the fourth direction intersect each other two by two. After a part of the light entering the second structural subsection 12 passes through the plurality of second beam splitters 121 to realize the first pupil expansion, the part of the light enters the first structural subsection 11 and the second waveguide structure 2 in sequence to complete the second pupil expansion and the third pupil expansion. The other part of the light entering the second structural subsection 12 passes through the second beam splitters 122 to realize the first pupil expansion, and then enters the third structural subsection 13 and the second waveguide structure 2 in sequence to complete the second pupil expansion and the third pupil expansion.

Exemplarily, as shown in fig. 5 and 8, a first waveguide structure 1 and a second waveguide structure 2 are disposed between a first plane S1 and a second plane S2 of the triple-pupil expansion device, the first waveguide structure 1 and the second waveguide structure 2 are disposed up and down along the Y direction in fig. 3, the first waveguide structure 1 and the second waveguide structure 2 may use common materials with lower refractive indexes, such as H-BAK5, and the refractive index n is 1.56, the first waveguide structure 1 performs twice X-direction (horizontal direction) pupil expansion on incident parallel light beams, and the second waveguide structure 2 performs once Y-direction (vertical direction) pupil expansion on light beams after the pupil expansion through the first waveguide structure 1, so as to meet the requirement of the two-dimensional waveguide structure on pupil expansion and realize triple-pupil expansion of the incident light beams. In particular, the first waveguide structure 1 comprises a first structural branch 11, a second structural branch 12 and a third structural branch 13 arranged in sequence along the X-direction in fig. 3. Where the X direction is parallel to the first plane S1 and the Y direction intersects the first direction, e.g., the Y direction is orthogonal to the X direction.

The first structural subsection 11 comprises a first beam splitter 111, the third structural subsection 13 comprises a third beam splitter 131 and the second waveguide structure 2 comprises a plurality of fourth beam splitters 21. The second structure subsection 12 is additionally arranged in the middle area of the first waveguide structure 1, the second structure subsection 12 comprises a plurality of second beam splitters 121 and a plurality of second beam splitters 122, parallel light beams are split into left view light beams, middle view light beams and right view light beams, and the first beam splitter 111, the plurality of second beam splitters 121, the plurality of second beam splitters 122, the third beam splitter 131 and the fourth beam splitter 21 have the functions of splitting and turning the light beams and adjusting the propagation direction of the light beams. For example, the incident beam is split by additionally plating a reflective film and a transmissive film on the surface of the lens. Specifically, the middle position of the entrance pupil in the first waveguide structure 1 is adjusted, and along the Y direction in the figure, when parallel light beams emitted by the optical engine enter the second sub-structure 12 through the entrance pupil in sequence through the second sub-structure 121 and the second sub-structure 122, the light beams reaching the second sub-structure 121 are split into a first part of light and a second part of light, the first part of light is reflected by the second sub-structure 121 to realize the first pupil expansion along the horizontal direction and then reach the first sub-structure 111, the second part of light is reflected by the first sub-structure 111 to realize the second pupil expansion along the horizontal direction and then reach the fourth sub-structure 21, the first pupil expansion along the vertical direction is realized through the reflection of the fourth sub-structure 21 and then the light beams are emitted to reach the user's eye for imaging, and the right triple-view-field pupil imaging is formed; the second part of light is reflected by the second beam splitter 122 to realize the first pupil expansion along the horizontal direction and then reach the third beam splitter 131, reflected by the third beam splitter 131 to realize the second pupil expansion along the horizontal direction and then reach the fourth beam splitter 21, reflected by the fourth beam splitter 21 to realize the first pupil expansion along the vertical direction and then exit to the eyes of the user for imaging, and the left view field three-time pupil expansion imaging is formed. The second structure subsection 12 is added to ensure that the field angle, the eye box and the exit pupil distance are kept unchanged, the pupil expanding frequency of incident light in the horizontal direction is increased, the pupil expanding range in the horizontal direction is expanded, the position of the entrance pupil is adjusted, the size of the two-dimensional waveguide sheet can be effectively reduced, image display of the full field of view is realized, the two-dimensional waveguide sheet is more suitable for the optimal position of human vision, the machining difficulty is reduced, and the light energy utilization rate is improved.

Further, as shown in fig. 6 and 7, the second beam splitter 121 and the second beam splitter 122 have a plurality of structural arrangements, and theoretically, the larger the number of the second beam splitter 121 and the second beam splitter 122 is, the wider the pupil is expanded in the horizontal direction for the first time of the entrance pupil light beam, and the specific number needs to be set in accordance with actual needs.

Alternatively, the second beam splitter 121 and the second beam splitter 122 are symmetrically arranged along the first direction (shown as the X direction in the figure). By adopting the symmetrical structure, the parallel light beams which are emitted by the control light machine and carry virtual image information enter through the entrance pupil to sequentially reach the second beam splitter 121 and the second beam splitter 122, the left and right view field range formed by beam splitting is controlled, and full view field virtual image display is realized.

When the second splitter 121 and the second splitter 122 are symmetrically disposed along the first direction, the number of the second splitters 121 and the number of the second splitters 122 are equal. It is understood that the number of the second beam splitter 121 and the number of the second beam splitter 122 may not be equal, and the structural diagram of the second structural sub-part may be as shown in fig. 7.

It should be noted that adjacent beam splitters in the second structural subsection 12 may be fixedly attached by gluing. A certain gap may be formed between adjacent beam splitters in the second structural sub-portion 12 (as shown in fig. 6), as long as it can be ensured that parallel light beams carrying virtual image information emitted from the optical engine sequentially reach the second beam splitter 121 and the second beam splitter 122 through the entrance pupil, and the left and right field ranges formed by beam splitting are controlled, so as to realize full-field virtual image display.

The second plurality of beam splitters 121 and the second plurality of beam splitters 122 in the second structural unit 12 may be a single beam splitter or a plurality of mirror surfaces of one prism. For example, four sides of one quadrangular prism may be used as two second beam splitters 121 and two second beam splitters 122 as in fig. 5.

Optionally, the second beam splitters 121 are arranged in parallel at equal intervals; the second plurality of second beam splitters 122 are arranged in parallel at equal intervals. The light machine is controlled to emit parallel light beams carrying virtual image information to sequentially reach the second beam splitter 121 and the second beam splitter 122 through entrance pupil incidence, and primary imaging is performed in the horizontal direction respectively, so that the imaging uniformity of virtual images is improved, and the visual imaging effect is improved.

On the basis of the above embodiment, as shown in fig. 5 to 8, optionally, an included angle between the second beam splitter and the first direction is α, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is γ; the angle between the second beam splitter and the first direction is beta, and the angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma (not shown in the figure); the included angle between the second beam splitter and the second beam splitter is 180 degrees- (alpha + beta); the included angle between the normal direction of the fourth beam splitter and the normal direction of the first plane is theta;

Exemplarily, as shown in the front view and the left view of the pupil expanding device in fig. 5, the second beam splitter 121 is arranged to have an angle α with respect to the first direction (X direction in the figure), 0 < α <90 °, preferably, α ═ 45 °, the angle γ (not shown in the figure) between the normal direction of the second beam splitter and the normal direction of the first plane, 80 ° < γ <90 °, and the light beam incident on the entrance pupil reaches the second beam splitter 121 and is reflected to the first beam splitter 111 to form a left field of view light beam; an included angle between the second beam splitter 122 and the first direction is set to be β, β is greater than 0 and less than 90 degrees, preferably, β is 45 degrees, an included angle between a normal direction of the second beam splitter 122 and a normal direction of the first plane is γ (not shown in the figure), a light beam incident from the entrance pupil reaches the second beam splitter 122 and is reflected to the third beam splitter 131 to form a left field of view light beam, and meanwhile, an included angle between the second beam splitter 121 and the second beam splitter 122 is set to be 180 degrees- (α + β), so that the entrance pupil light beam completely irradiates surfaces of the second beam splitter 121 and the second beam splitter 122, and the energy utilization rate of the entrance pupil light beam is improved.

Further, as shown in the left view of the pupil expanding device in fig. 5, in consideration of the most comfortable field of view of human eyes, the angle between the normal direction of the fourth beam splitter 21 and the normal direction of the first plane S1 is set to be θ, where θ is more than 20 and less than 28 °, and the exit pupil light beam reflected and coupled out by the fourth beam splitter 21 is adjusted to couple into the user' S eyes at the optimal viewing angle, so that the visual effect is optimal.

In summary, the pupil expanding device provided by the present invention can increase the pupil expanding times of the incident light in the horizontal direction and expand the pupil expanding range in the horizontal direction by adding the second structural part under the condition of keeping the angle of view, the eye box and the exit pupil distance unchanged, can effectively reduce the size of the two-dimensional waveguide sheet, realizes the image display in the full field of view, is more suitable for the optimal position of human vision, and simultaneously reduces the machining difficulty and improves the light energy utilization rate.

Optionally, a certain proportion of reflective films are additionally plated on the surfaces of the second beam splitter 121 and the second beam splitter 122. With reference to fig. 6, in this structure, the parallel light beam carrying the virtual image information emitted from the optical engine enters through the entrance pupil to reach the surface of the second beam splitter 121 and then is split into a first partial light beam and a second partial light beam, and the entire field of view of the virtual image is split into two parts, i.e., a left field of view and a right field of view, by the second beam splitter 121 and the second beam splitter 122. In the direction of the right field of view, a first part of light rays are reflected by the 2 second beam splitters 121 and then sequentially reach the plurality of first beam splitters 111 arranged in parallel, the light beams are turned for multiple times and then reach the second waveguide structure 2 along the Y direction and then enter the eyes of a user, each second beam splitter 121 and each first beam splitter 111 form primary images for the exit pupil, namely, the first pupil expansion is performed along the horizontal direction by the second beam splitter 121, and the second pupil expansion is performed by the first beam splitter 111 along the horizontal direction, so that the secondary pupil expansion of the right field of view in the horizontal direction is realized; in the left visual field direction, the second part of light rays are reflected by the second beam splitter 122 and then sequentially reach a plurality of third beam splitters 131 which are arranged in parallel, the light beams are turned for a plurality of times and then reach the second waveguide structure 2 and then enter the eyes of the user, each second beam splitter 122 and each third beam splitter 131 form primary images for the exit pupil, namely, the first pupil expansion is carried out on the second beam splitter 122 along the horizontal direction, and the second pupil expansion is carried out on the third beam splitters 131 along the horizontal direction, so that the secondary pupil expansion of the left visual field in the horizontal direction is realized; the light beam reaching the second waveguide structure 2 is sequentially deflected and coupled out to the eyes of the user by the plurality of fourth beam splitters 21 so as to be received by the eyes of the user, and each fourth beam splitter 21 forms an image of the exit pupil once and realizes the pupil expansion in the vertical direction, thereby realizing the full-field imaging of the virtual image information in the eyes of the user.

Through setting up a plurality of parallel arrangement's second beam splitter 121 and a plurality of parallel arrangement's second beam splitter 122 structure, change the visual field to the middle zone, the light beam gets into the middle zone of first waveguide structure 1 from the entrance pupil, this kind of mode of visual field separately transmission about can realizing, the transmission that the height of first waveguide structure 1 (upper structure waveguide piece) only needs to satisfy half visual field just can realize the display of full visual field, and in ordinary two-dimensional waveguide piece, the transmission that the height of upper structure waveguide piece needs to satisfy whole visual field just can show complete image, consequently this kind of structure can reduce the volume of two-dimensional waveguide piece greatly, make people's eye position more close to the best position of watching the image simultaneously, not only so, in the left and right structures, also can reduce beam splitter quantity, thereby reduce the processing degree of difficulty, improve the light energy utilization ratio. In addition, because the second structure subsection 12 (middle structure) also plays a role of pupil expansion for the first time in the horizontal direction, the distance between two beam splitters in the first waveguide structure 1 (upper structure) can be increased, the processing difficulty of the upper structure is indirectly reduced, and the field angle, the eye box and the exit pupil distance can be kept unchanged by adopting common low-refractive-index materials, so that the purpose of reasonably adjusting the imaging field range of the triple pupil expansion device and improving the visual experience of a user is achieved.

Optionally, the triple pupil expansion device further comprises a coupling-in structure 30; the incoupling structure 30 comprises a prism for incoupling the parallel light beams exiting the light engine into the second structural section 12. The capacity utilization rate of light can be improved, and the field-of-view imaging effect can be improved.

On the basis of the above-described embodiment, as shown in fig. 5 and 8, optionally, the number of the first beam splitter 111 is multiple. The plurality of first beam splitters 111 are sequentially arranged in parallel along a second direction (shown as an X direction in the figure), and the plurality of first beam splitters 111 extend along the fourth direction.

The number of the third beam splitters 131 may be multiple, a plurality of the third beam splitters 131 are sequentially arranged in parallel along the second direction, and the plurality of the third beam splitters 131 extend along the third direction. The fourth beam splitter 21 includes a plurality of fourth beam splitters 21, and the plurality of fourth beam splitters 21 are sequentially arranged in parallel along the first direction (as shown in the Y direction in the figure).

Illustratively, the first structural subsection 11 and the third structural subsection 13 are symmetrically arranged along the first direction. The first beam splitters 111 and the third beam splitters 131 are arranged at equal intervals along the direction X in the figure, light beams incident from the entrance pupil are split by the second structure sub-assembly 12 and then are respectively turned by the first beam splitters 111 and the third beam splitters 131 to form primary images at equal intervals on the exit pupil, so that the pupil can be expanded at equal intervals in the horizontal direction, the primary images at equal intervals are formed after the light beams are split and turned when reaching the fourth beam splitters 21 arranged in parallel at intervals and enter eyes (eye boxes) of a user, the pupil can be expanded at equal intervals in the vertical direction, the processing difficulty can be reduced through the parallel arrangement at equal intervals, the field angle is increased, and the visual imaging effect of the user is improved.

An embodiment is listed below with reference to the figures, and with reference to fig. 9, a triple-pupil expansion device provided in the above embodiment is adopted, and fig. 9 is a left-view optical path diagram of a pupil expansion device provided in an embodiment of the present invention. Taking 7

first beam splitters

111, 7

third beam splitters

131, and 5 fourth beam splitters 21 as examples, the triple pupil expanding device provided by the embodiment of the present invention is adopted, referring to fig. 8, in combination with formula 1.3 and formula 1.4, where, the length units in fig. 5-9 are: mm (millimeters):

n*sinα_h-in＝sinα_h， (1.3)；

h≈L/2*tanα_h-in， (1.4)；

where n is the refractive index of the beam splitter, h is the height of the first waveguide structure 1 after decreasing in the first direction, α_hIs the longitudinal field angle, alpha, of the exit pupil beam_h-inThe longitudinal field angle of the exit pupil beam in the second waveguide structure 2, 2L is the path length traveled by the light beam within the first waveguide structure 1.

As shown in fig. 9, by adding a plurality of second parallel beam splitters 121 and a plurality of second parallel beam splitters 122, the entrance pupil of the incident light beam is incident from the middle area of the first waveguide structure 1, and the field of view is changed to the middle area, so that the size of the two-dimensional waveguide plate can be effectively reduced while maintaining the field angle of 55 °, the eye box 10 and the exit pupil distance 20 unchanged, that is, the height h of the first waveguide structure 1 is about 14.18mm, and compared with the height 22.2mm of the structural waveguide plate on the existing ordinary two-position waveguide structure, the height is reduced, the size is reduced, the processing difficulty and cost are reduced, the structure is more compact, and the light energy utilization rate is improved; the pupil expanding device not only expands the pupil for 2 times in the horizontal direction, but also expands the pupil once in the vertical direction, so that the full field range is expanded, the positions of human eyes are closer to the optimal positions for watching images, and the visual experience effect is improved.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that the features of the various embodiments of the invention may be partially or fully coupled to each other or combined and may be capable of cooperating with each other in various ways and of being technically driven. Numerous variations, rearrangements, combinations, and substitutions will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A pupil expanding device is characterized by comprising a first plane, a second plane, a first waveguide structure and a second waveguide structure, wherein the first plane and the second plane are arranged in parallel, and the first waveguide structure and the second waveguide structure are arranged between the first plane and the second plane and are sequentially arranged along a first direction; the first waveguide structure comprises a first structure subsection, a second structure subsection and a third structure subsection which are arranged in sequence along a second direction, and the first direction is parallel to the first plane;

2. The pupil expanding device according to claim 1, wherein the first structural subdivision comprises a plurality of first beam splitters, the plurality of first beam splitters being arranged in parallel one after the other in the second direction, and the plurality of first beam splitters extending in the fourth direction.

3. The pupil expanding device according to claim 2, wherein the third structural subsection comprises a plurality of third beam splitters, the plurality of third beam splitters are arranged in parallel in sequence along the second direction, and the plurality of third beam splitters extend along the third direction.

4. The pupil expanding device according to claim 3, characterized in that the first and third structural sections are symmetrically arranged along the first direction.

5. The pupil expanding device according to claim 4, wherein the second waveguide structure comprises a plurality of fourth beam splitters, which are arranged in parallel in sequence along the first direction.

6. The pupil expanding device according to claim 5, wherein a plurality of the first beam splitters are sequentially arranged in parallel at equal intervals along the second direction;

7. The pupil expanding device according to claim 1, wherein the second sub-mirror and the second sub-mirror are symmetrically arranged along the first direction.

8. The pupil expanding device according to claim 1, wherein a plurality of the second sub-beam splitters are equally spaced; the second beam splitters are arranged at equal intervals.

9. The pupil expanding device according to claim 1, wherein the fourth direction forms an angle α with the first direction, and the normal direction of the second beam splitter forms an angle γ with the normal direction of the first plane; an included angle between the third direction and the first direction is beta, and an included angle between the normal direction of the second beam splitter and the normal direction of the first plane is gamma; the angle between the third direction and the fourth direction is 180 ° - (α + β);

10. The pupil expanding device according to claim 1, characterized in that it further comprises a coupling structure;