CN112462519A

CN112462519A - Grating waveguide display device with uniform light emission

Info

Publication number: CN112462519A
Application number: CN202011408565.5A
Authority: CN
Inventors: 王丙杰; 张威; 李双龙; 史晓刚
Original assignee: Beijing Xloong Technologies Co ltd; Beijing Xloong Technology Co ltd
Current assignee: Beijing Xloong Technologies Co ltd; Beijing Xloong Technology Co ltd
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-03-09

Abstract

The invention discloses a grating waveguide display device with uniform light emission, which comprises a grating waveguide device, a light beam replication prism, a projection system, a first lens and a second lens, wherein the light beam replication prism is fixedly installed at one end of the grating waveguide device, the projection system is fixedly installed at one side of the light beam replication prism, the first lens and the second lens are parallel to each other, the grating waveguide device is divided into five areas, the grating waveguide device consists of a first incident grating, a second incident grating, a first turning grating, a second turning grating and an emergent grating, and the first incident grating is positioned at one side of the second incident grating. When the grating waveguide device is used, the energy utilization rate can be improved, the generation of stray light is reduced, the performance of the whole grating waveguide device is improved, and meanwhile, the energy of the transmitted light beam is more uniform, so that the display uniformity of the device is better.

Description

Grating waveguide display device with uniform light emission

Technical Field

The invention relates to the technical field of display equipment, in particular to a grating waveguide display device with uniform light emission.

Background

Near-eye display devices have evolved rapidly as virtual reality and augmented reality technologies have become recognized and accepted. The near-to-eye display in the augmented reality technology can superimpose a virtual image onto a real scene, and simultaneously has perspective characteristic, so that the normal observation of the real scene is not influenced. Means for coupling the virtual image into the human eye using conventional optical elements have been employed, including prisms, half-mirrors, free-form waveguides, mirror array waveguides, and the like. The grating waveguide display technology is to realize the incidence, turning and emergence of light rays by using a diffraction grating, realize light ray transmission by using the total reflection principle, transmit an image of a micro display to human eyes and further see a virtual image; because the total reflection principle the same as that of the optical fiber technology is adopted, the grating waveguide display device can be made as light, thin and transparent as common spectacle lenses. And because the turning of the light is realized by the diffraction grating on the surface of the lens, the shape of the lens is basically irrelevant to the shape of the bottom plate, the lens is easy to manufacture in batches, and the production cost is low.

However, the conventional grating waveguide display device with uniform light emission has the following disadvantages:

grating waveguide devices are generally composed of an entrance grating, a turning grating, and an exit grating. The incident grating diffracts incident light in two symmetrical directions (one is called +1 st order diffraction light, and the other is called-1 st order diffraction light). One of the diffracted lights is transmitted to the emergent grating through the turning grating, and is guided out of the grating waveguide device through the emergent grating and transmitted into human eyes to be received. The other diffracted light is generally not used efficiently and lost as stray light. This not only increases the stray light of the system, affects the display effect, but also reduces the light energy transmission efficiency. In addition, only one incident grating and one turning grating are provided, and the light transmission uniformity is low.

Disclosure of Invention

The invention aims to provide a grating waveguide display device with uniform light emission, and aims to solve the problems that in the background technology, only diffraction light in one direction of an incident grating is utilized, the energy utilization rate is low, stray light is easy to generate, the performance of the whole grating waveguide device is influenced, and meanwhile, only diffraction light in one direction of the incident grating is utilized, the energy uniformity of a transmitted light beam is poor, and the display uniformity of the device is poor.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides an even grating waveguide display device of light-emitting, includes grating waveguide device, light beam replication prism, projection system, a lens and No. two lenses, grating waveguide device one end fixed mounting has the light beam replication prism, light beam replication prism one side fixed mounting has projection system, a lens and No. two lenses are parallel to each other, grating waveguide device falls into five regions, grating waveguide device comprises incident grating, No. two incident gratings, a turn grating, No. two turn gratings and emergent grating, an incident grating is located No. two incident grating one sides, a turn grating and No. two turn gratings are located a turn grating and No. two turn grating both ends respectively.

Preferably, the beam replication prism includes a light incident surface, a first light exit surface, and a second light exit surface, which are parallel to each other.

Preferably, a semi-transparent semi-reflecting optical surface and an internal reflecting optical surface are arranged inside the light beam replication prism, and the semi-transparent semi-reflecting optical surface and the internal reflecting optical surface are parallel to each other.

Preferably, the surfaces of the light incidence surface, the first light emergence surface and the second light emergence surface which are parallel to each other are plated with antireflection films.

Preferably, the second lens is a semi-transparent and semi-reflective lens, and the first lens is a reflective lens.

Preferably, the projection system emits a light beam, and the light beam is incident on the light beam replication prism from the light incident surface to obtain a first reflected light, a transmitted light, and a second reflected light, and the transmitted light and the second reflected light are parallel to each other.

The invention provides a grating waveguide display device with uniform light emission, which has the following beneficial effects:

(1) the invention adopts a grating waveguide structure of two incident gratings, two turning gratings and an emergent grating, wherein the two turning gratings are arranged at two sides of the incident grating, so that diffracted light in two directions generated by the incident grating can respectively enter the two turning gratings, and the emergent grating is arranged at one side of the two turning gratings, so that the diffracted light generated by the incident grating can be incident to the emergent grating after being diffracted and conducted by the two turning gratings.

(2) The two incident gratings are arranged in a staggered manner, so that diffracted light generated by the two incident gratings is diffracted by the two turning gratings, and then a light beam transmitted to the emergent grating has no gap in the middle, and the light beam of the projection system is copied by adopting a light beam copying prism, so that the device can enable the grating waveguide device with the two incident gratings to work normally only by configuring one projection system.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of a grating waveguide device structure according to the present invention;

FIG. 3 is a schematic view of a beam replicating prism structure according to the invention;

FIG. 4 is a schematic cross-sectional view of the present invention;

fig. 5 is a schematic structural view of a first lens and a second lens of the present invention.

In the figure: 210. a projection system; 300. a grating waveguide device; 312a, incident grating number one; 312b, incident grating number two; 314a, first turning grating; 314b, second turning grating; 316. emitting a grating; 400. a beam replication prism; 41. an internal reflection optical surface; 42. a semi-transmitting semi-reflecting optical surface; 43. a light incident surface; 44. a first light exit surface; 45. a second light exit surface; 430. a first lens; 440. a second lens; 51. a light beam; 52. a first reflected light; 53. transmitting light; 54. the second reflects light.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

As shown in fig. 1 to 5, the present invention provides the technical solutions: the utility model provides a grating waveguide display device that light-emitting is even, includes grating waveguide device 300, beam replication prism 400, projection system 210, a lens 430 and No. two lenses 440, grating waveguide device 300 one end fixed mounting has beam replication prism 400, beam replication prism 400 one side fixed mounting has projection system 210, a lens 430 and No. two lenses 440 are parallel to each other, grating waveguide device 300 divides into five regions, grating waveguide device 300 comprises incident grating 312a, No. two incident grating 312b, turn grating 314a, No. two turn grating 314b and emergent grating 316, incident grating 312a is located No. two incident grating 312b sides, turn grating 314a and No. two turn grating 314b are located No. one turn grating 314a and No. two turn grating 314b both ends respectively.

The beam replication prism 400 includes a light incident surface 43, a first light exit surface 44, and a second light exit surface 45, and the light incident surface 43, the first light exit surface 44, and the second light exit surface 45 are parallel to each other.

The beam replication prism 400 is internally provided with a semi-transparent and semi-reflective optical surface 42 and an internal reflection optical surface 41, and the semi-transparent and semi-reflective optical surface 42 and the internal reflection optical surface 41 are parallel to each other.

The surfaces of the light incident surface 43, the first light emergent surface 44 and the second light emergent surface 45 which are parallel to each other are coated with antireflection films.

The second lens 440 is a transflective lens, and the first lens 430 is a reflective lens.

The projection system 210 emits a light beam 51, and the light beam 51 is incident on the beam replication prism 400 from the light incident surface 43 to obtain a first reflected light 52, a transmitted light 53, and a second reflected light 54, and the transmitted light 53 and the second reflected light 54 are parallel to each other.

It should be noted that, in operation, the display device is composed of the grating waveguide device 300, the beam replication prism 400 and the projection system 210. The structure of the grating waveguide device is shown in figure 2. The waveguide device consists of an optical substrate and a grating positioned on the surface of the optical substrate, wherein the grating can be a surface relief grating, a holographic grating and the like. The grating is divided into five regions, which form five main functional regions of the grating waveguide device, namely two incident grating regions (312a,312b), two turning grating regions (314a,314b) and an emergent grating region (316). The

entrance gratings

312a and 312b are used to guide a virtual image beam having a certain field angle and a certain entrance pupil diameter into the grating waveguide device 300. The

incident gratings

312a,312b diffract the incident light in two approximately opposite directions, a portion of which is generally +1 st order diffracted light directed toward the turning grating region 314a, and a portion of which is generally-1 st order diffracted light directed toward the turning grating region 314 b. After the two portions of diffracted light are transmitted through the turns of the turning

gratings

314a and 314b, both portions of the diffracted light enter the exit grating area 316 and are effectively utilized. Therefore, the structure can effectively utilize the diffracted beams in different directions generated by the incident grating, greatly improve the light energy conduction efficiency and reduce stray light.

The turning grating 314a may expand a portion of the diffracted beams of the

entrance gratings

312a,312b, typically +1 st order diffracted beams, in a vertically upward direction while producing diffracted beams that are directed toward the exit grating 316. The turning grating 314b can expand another part of the diffracted light beams of the

incident gratings

312a and 312b, which are typically-1 st-order diffracted light beams, in a vertical downward direction, and generate diffracted light beams transmitted toward the exit grating 316, and the exit grating 316 can expand the light beams in a horizontal direction, and transmit light energy out of the grating waveguide device 300, so that the image light beams transmitted by the grating waveguide device 300 exit from the exit pupil and are perceived by human eyes, and a virtual image is seen by human eyes.

In this structure, the two beams of diffracted light generated by the

incident gratings

312a and 312b both carry the display and viewing angle information of the virtual image, and the width of the y-axis direction under the same size of the exit grating 316, the optical path of the diffracted light at each side of the structure conducted along the y-axis or the negative y-axis in the turning grating is shorter than that of the conventional grating waveguide structure, and is approximately half of the conventional optical path, because the energy of the diffracted light is attenuated during the conduction along the y-axis or the negative y-axis in the turning grating, which results in the uneven energy of the conducted light beam, and the attenuation degree is proportional to the optical path of the diffracted light conducted along the y-axis or the negative y-axis in the turning grating, so the grating waveguide structure in this patent can significantly improve the uniformity of the light beam conduction, thereby significantly improving the display uniformity of the whole grating waveguide display device.

In the grating waveguide device 300, there are two

incident grating regions

312a,312b, and the incident grating 312a and the incident grating 312b are not at the same horizontal position, but are staggered with each other, so that there is almost no gap between the turning grating 314a and the turning grating 314b as viewed in the horizontal direction. This allows no gap between the light propagating from the turning grating 314a to the exit grating 316 and the light propagating from the turning grating 314b to the exit grating 316.

If there is a gap between the light transmitted from the turning grating 314a to the exit grating 316 and the light transmitted from the turning grating 314b to the exit grating 316, the gap will cause no outgoing light in the corresponding area of the exit grating 316, i.e. a dark band is generated. Since the gap D exists in the central region of the grating waveguide device, the dark band is also located in the central region. The central area is the main area where human eyes receive the grating when the grating waveguide device works, and the dark band of the area can seriously affect the working performance of the grating waveguide device.

By arranging the two

incident gratings

312a and 312b and arranging the two incident gratings in a staggered manner, a dark zone in the central area of the grating waveguide device is avoided, light conduction is more uniform, and the excellent performance of the grating waveguide is ensured.

The beam replication prism 400 is structured as shown in fig. 3. The prism material can be optical glass or plastic. The beam replication prism 400 includes three light transmitting surfaces 43, 44, and 45, where 43 is a light incident surface and 44 and 45 are light exit surfaces. The prism further includes a transflective optical surface 42, located within the beam replicating prism 400, that splits the beam incident thereon into two portions, one transmissive and one reflective. An internally reflective optical surface 41 may reflect light beams incident thereon. The light beam 51 emitted by the projection system 210 is incident into the light beam replication prism 400 from the light incidence surface 43, and when the light beam is incident into the half-transmitting and half-reflecting optical surface 42, the light beam is divided into two beams, and one beam of transmitted light 53 is transmitted through the prism and is emitted from the light transmitting surface 45; one beam of reflected light 52 enters the internally reflective optical surface 41, is reflected by the internally reflective optical surface 41 to generate reflected light 54, and the reflected light 54 is emitted through the light-transmitting surface 44. The outgoing transmitted light 53 and 54 can be made parallel to each other by arranging the light-transmitting

surfaces

43, 44, 45 and the internal reflection optical surface 41, the half-transmission optical surface 42, and the included angles between the five optical surfaces. In a typical implementation, the internally reflective optical surface 41 and the transflective optical surface 42 are parallel to each other, and the three light-

transmissive surfaces

43, 44 and 45 are parallel to each other. The three light-transmitting

surfaces

43, 44 and 45 may be coated with an antireflection film to increase light-transmitting performance. The transflective optical surface 42 typically has a transmission to reflection energy ratio of 1: 1 so that the transmitted

light

53 and 54 are of the same or approximately the same energy, ensuring beam uniformity.

Fig. 4 shows another alternative embodiment of a beam replicating prism 400. In this embodiment, two parallel thin

optical lenses

430 and 440 are included, and the material may be glass, plastic or other optical materials. The second lens 440 is a half-mirror lens, and can separate the light beam incident thereon into two beams, one beam is transmitted light and the other beam is reflected light. First lens 430 is a mirror lens. The light beam is incident on the half mirror 440 and is divided into two beams, the transmitted light passes through the second mirror 440 and continues to be transmitted downwards, the reflected light is transmitted towards the first mirror 430 and transmitted downwards after being reflected by the first mirror 430, and the transmitted light of the second mirror 440 and the reflected light of the first mirror 430 are parallel to each other according to the law of optical reflection because the first mirror 430 and the second mirror 440 are arranged in parallel.

As shown in fig. 5, the light beam with image information from the projection system 210 is projected onto a beam replication prism 400, and the beam replication prism 400 modulates one light beam from the projection system 210 into two parallel light beams. The light-emitting position of the beam replication prism 400 corresponds to the incident grating of the grating waveguide device 300, and two parallel light beams emitted from the beam replication prism 400 are incident to the two

incident gratings

312a and 312b of the grating waveguide device 300, are transmitted, expanded and emitted by the grating waveguide device 300, and then are incident to human eyes to be perceived.

The projection system 210 is used to generate a projected beam with image information, which may be an LCOS Micro-projection system, a DLP Micro-projection system, an OLED Micro-projection system, a Micro LED Micro-projection system, an LBS laser scanning Micro-projection system, or the like. LCOS micro-projection systems and DLP micro-projection systems typically include a micro-display LCOS or DMD, a backlight LED or laser and an optical lens set, etc.; the OLED Micro-projection system and the Micro LED Micro-projection system generally comprise a Micro-display OLED or a Micro LED and an optical lens group; LBS laser scanning micro-projection systems typically comprise a laser source, a collimating system and a scanning device MEMS or scanning fiber, etc.

In a conventional grating waveguide display device, there is only one incident grating, and the light beam density transmitted to the turning grating after the incident grating is diffracted and transmitted to the exit grating 316 by the turning grating is small, and in order to ensure the uniformity of the light beam, the projection system 210 needs to have a large beam diameter. In this embodiment, the grating waveguide has two incident gratings, and the light beam density is approximately twice that of the conventional grating waveguide display device, so that the projection system 210 can have a small light beam diameter, and the reduction of the light beam diameter can greatly reduce the size of the projection system 210, thereby being beneficial to reducing the size of the whole display device.

In the scheme, one beam emitted by the projection system 210 can be modulated into two parallel beams by the beam replication prism 400, so that the grating waveguide device 300 with two incident gratings can work normally. Two projection systems are not needed, so that the system function is ensured, the structure is simplified, and the complexity and the volume are reduced.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A grating waveguide display device with uniform light emission is characterized in that: comprises a grating waveguide device (300), a beam replication prism (400), a projection system (210), a first lens (430) and a second lens (440), one end of the grating waveguide device (300) is fixedly provided with a light beam replication prism (400), a projection system (210) is fixedly arranged on one side of the beam replication prism (400), the first lens (430) and the second lens (440) are parallel to each other, the grating waveguide device (300) is divided into five regions, the grating waveguide device (300) is composed of a first incident grating (312a), a second incident grating (312b), a first turning grating (314a), a second turning grating (314b) and an emergent grating (316), the first incident grating (312a) is positioned at one side of the second incident grating (312b), the first-turn grating (314a) and the second-turn grating (314b) are respectively positioned at two ends of the first-turn grating (314a) and the second-turn grating (314 b).

2. A grating waveguide display device with uniform light extraction as claimed in claim 1, wherein: the beam replication prism (400) includes a light entrance surface (43), a first light exit surface (44), and a second light exit surface (45).

3. A grating waveguide display device with uniform light emission as claimed in claim 2, wherein: the light incident surface (43), the first light exit surface (44), and the second light exit surface (45) are parallel to each other.

4. A grating waveguide display device with uniform light extraction as claimed in claim 1, wherein: the beam replication prism (400) is internally provided with a semi-transparent semi-reflective optical surface (42) and an internal reflection optical surface (41), and the semi-transparent semi-reflective optical surface (42) and the internal reflection optical surface (41) are parallel to each other.

5. A grating waveguide display device with uniform light emission as claimed in claim 3, wherein: and the surfaces of the light incidence surface (43), the first light emergent surface (44) and the second light emergent surface (45) which are parallel to each other are coated with antireflection films.

6. A grating waveguide display device with uniform light extraction as claimed in claim 1, wherein: the second lens (440) is a semi-transparent and semi-reflective lens.

7. A grating waveguide display device with uniform light extraction as claimed in claim 1, wherein: the first lens (430) is a reflector lens.

8. A grating waveguide display device with uniform light extraction as claimed in claim 1, wherein: the projection system (210) emits a light beam (51), the light beam (51) is incident to a light beam replication prism (400) from a light incidence surface (43) to obtain a first reflected light (52), a transmitted light (53) and a second reflected light (54), and the transmitted light (53) and the second reflected light (54) are parallel to each other.