CN211826603U - Optical waveguide, display device, and electronic apparatus - Google Patents

Abstract

The utility model provides an optical waveguide, display device and electronic equipment, the optical waveguide includes: the coupling-in area is used for coupling in the light beams in the preset field direction; a transfer region including N waveguide layers for propagating the light beam coupled in through the coupling-in region, wherein N is greater than or equal to 2; an outcoupling region for extracting the light beam propagating through the transfer region; the transmission region is arranged on a light path between the coupling-in region and the coupling-out region, N-1 angle selection films with different angle selections are arranged among the N waveguide layers, and the N-1 angle selection films with different angle selections selectively reflect or transmit the light beams to enable the light beams to be emitted through the same position of the coupling-out region. The utility model discloses can realize propagation cycle's unanimity, reach good display effect.

Description

Optical waveguide, display device, and electronic apparatus

Technical Field

The utility model relates to an optical waveguide technical field especially relates to an optical waveguide, display device and electronic equipment.

Background

In the prior art, head-mounted display devices employ planar optical waveguides as display devices, including diffractive optical waveguides, array optical waveguides, and the like. The diffraction optical waveguide couples input light into the waveguide through the coupling-in grating for total reflection transmission, and then the exit pupil expansion and light coupling-out are realized through the coupling-out grating, and in the augmented reality display technology, the number of times of the exit pupil expansion directly influences the watching effect of a user. However, during total reflection, the propagation periods of the light rays at different angles are not uniform, which leads to differences in the number of contributions from the outcoupling grating. Therefore, there may be a large difference in the number of times of expanding the exit pupil of the gratings with different angles, thereby affecting the final display effect.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problem, the utility model provides an optical waveguide, display device and electronic equipment, it can realize propagation cycle's unanimity, reaches good display effect.

The utility model provides an optical waveguide, include: the coupling-in area is used for coupling in the light beams in the preset field direction;

a transfer region including a plurality of N waveguide layers for propagating the light beams coupled in through the coupling-in region, wherein N is greater than or equal to 2; an outcoupling region for extracting the light beam propagating through the transfer region; the transmission region is arranged on a light path between the coupling-in region and the coupling-out region, N-1 angle selection films with different angle selections are arranged among the N waveguide layers, and the N-1 angle selection films with different angle selections selectively reflect or transmit the light beams to enable the light beams to be emitted through the same position of the coupling-out region.

In some embodiments, the N waveguide layers are respectively used for regulating the propagation period of the light beam to make the propagation period of the light beam consistent.

In further embodiments, the coupling-in region and the coupling-out region comprise a diffraction grating or a diffractive optical element.

In still other embodiments, the coupling-in region and the coupling-out region are disposed on an outer surface and/or an inner surface of the transfer region.

In still other embodiments, the coupling-in region and the coupling-out region are disposed on the same surface or different surfaces of the transfer region.

In some embodiments, the angle selection film is a dielectric film comprising magnesium fluoride.

In some embodiments, the waveguide layer of the transfer region is further provided with a substrate comprising an optical glass or an optical resin material having a critical angle for total reflection.

The utility model also provides a display device, include such optical waveguide.

In some embodiments, the display device further includes a display engine for inputting an incident light beam having a preset angle of view to the coupling-in region of the optical waveguide.

The utility model also provides an electronic equipment, include as above display device.

The utility model has the advantages that: the optical waveguide formed by one or more layers of angle selection films is arranged, light beams coupled into the waveguide are divided into light beams in multiple directions according to different incident diffraction angles, effective transmission thicknesses of the light beams in different directions are inconsistent through angle selection conditions of the angle selection films, and therefore different propagation period differences of propagation angles are compensated, light propagation regulation is achieved, and propagation period consistency is achieved. Meanwhile, the light rays are uniformly regulated and controlled through transmission, and the emergent positions of the light beams are consistent, so that the optimization of the grating structure of each area of the optical waveguide structure based on the angle selection film is greatly facilitated, and a better display effect is achieved.

Drawings

Fig. 1 is a schematic diagram of an optical waveguide structure according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a curve of an angle selective membrane according to an embodiment of the present invention.

Fig. 3 is a schematic view of a display device based on an angle selection film according to an embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating a light propagation regulation according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings so as to better understand the present invention, but the following embodiments do not limit the scope of the present invention. In addition, it should be noted that the drawings provided in the following embodiments are only schematic diagrams for illustrating the basic concept of the present invention, and the drawings only show the related components of the present invention rather than the number, shape and size of the components in actual implementation, the shape, number and proportion of the components in actual implementation can be changed at will, and the layout of the components may be more complicated.

Fig. 1 is a schematic diagram of an optical waveguide structure according to an embodiment of the present invention. Theoptical waveguide 100 includes a coupling-inregion 101, atransfer region 102, and a coupling-outregion 103. Theinput region 101 is used for coupling in a light beam associated with an input image in a preset field direction, and thetransfer region 102 comprises N waveguide layers and is used for transferring the light beam coupled in through theinput region 101 to theoutput region 103, wherein N is more than or equal to 2; the coupling-outregion 103 is a light beam output end for outputting the light beam transmitted through thetransmission region 102, wherein thetransmission region 102 is disposed on the light path between the coupling-inregion 101 and the coupling-outregion 103, N-1 angle selection films with different angle selections are disposed between the waveguide layers, and the N-1 angle selection films with different angle selections can selectively reflect or transmit the light beam to enable the light beam to be output through the same position of the coupling-outregion 103. Theoptical waveguide 100 may be a head-mounted display device, such as an AR device, a heads-up display, or the like.

In one embodiment, the coupling-inarea 101 and the coupling-outarea 103 may be diffraction gratings with a grating period of several hundred nanometers, such as plane gratings, blazed gratings, or volume holographic gratings, and may also be Diffractive Optical Elements (DOEs), which separate and redirect incident light, the separation (referred to as optical order) and the angular variation depending on the characteristics of the diffraction gratings. Generally, the range of the coupling-inregion 101 is an entrance pupil range, the range of the coupling-outregion 103 is an exit pupil range, and further, the coupling-outregion 103 constitutes an exit pupil expansion region together with thetransfer region 102 to expand the beam exit pupil range. In one embodiment, the size of the coupling-inregion 101 and the coupling-outregion 103 may be determined according to the exit pupil size and characteristics of the optical system.

In an embodiment, as shown in fig. 3, the coupling-inregion 301 may be disposed on an outer surface and/or an inner surface of the transfer region 302 (as shown by a dotted line), the coupling-outregion 310 may be disposed on an outer surface and an inner surface of the transfer region 302 (as shown by a dotted line), and furthermore, the coupling-outregion 310 and the coupling-inregion 301 may be disposed on the same surface of thetransfer region 302 or on different surfaces (i.e., opposite surfaces) of thetransfer region 302, which are not limited herein. When the coupling-inregion 301 and the coupling-outregion 310 are disposed on the same surface of thetransfer region 302, they may be uniformly disposed on the outer surface of the surface, may be uniformly disposed on the inner surface of the surface, or may be disposed on the outer surface and the inner surface of the surface, respectively. In other embodiments, at least one of the in-coupling region 301 and the out-coupling region 310 may be integrally disposed with the transfer region, that is, the in-coupling region 301 and the out-coupling region 310 are part of the optical structure of thetransfer region 302.

FIG. 2 is a graphical illustration of an angle selective membrane. The angle selective film is an optical film with selective reflection characteristics, and can be distinguished from incident light beams with specific angles and wavelengths, namely, incident light beams with specific ranges of angles and wavelengths are reflected, and incident light beams with other angles and wavelengths are transmitted. In one embodiment, the optical waveguide based on the angle selection film has different reflectivities for incident light beams of different angles when the wavelength of the incident light beam is fixed, wherein, when the incident light beam is incident on the waveguide with the angle selection film at an incident angle of 30 °, the incident light beam with the incident angle less than or equal to 30 ° is reflected and is completely transmitted for the incident light beam with the incident angle greater than 30 °, thereby realizing the light beam selection effect of the angle selection film. Theoptical waveguide 100 is provided with a plurality of waveguide layers, and angle selection films with different reflectivities are plated between the waveguide layers, and the angle selection films can selectively reflect and transmit light beams between different waveguide layers according to the condition of satisfying total reflection, namely the angle selection condition, so that the incident light beams are emitted from the same position of the coupling-outregion 102, and the propagation period of the light beams is regulated and controlled to make the propagation period of the light beams consistent.

In one embodiment, the angle selection film is a dielectric film, and the material of the dielectric film is magnesium fluoride or the like. The angle selective film includes more than one layer, and the coating method includes magnetron sputtering, electron beam evaporation, vapor deposition, and chemical coating method, it should be understood that the angle selective film material, the number of layers, and the coating method can be set according to the specific wavelength and the specific requirement of the incident beam, and are not limited herein.

Fig. 3 is a display device based on an angle selection film according to an embodiment of the present invention. Fig. 3 includes: adisplay engine 10 shown facing afront side surface 311 of thelight guide 300, and thelight guide 300. The coupling-inregion 301 and the coupling-outregion 310 are disposed on the outer surface of thefront surface 311 of theoptical waveguide 300. Thedisplay engine 10 emits a light beam to thelight guide 300, diffracts the light beam from the coupling-inregion 301 to enter thetransmission region 302, and reflects the light beam to exit from the same position as the coupling-outregion 310.

In one embodiment, thedisplay engine 10 includes an illuminator 11, an image former 12, and acollimating lens 13, but is not limited thereto. The image former 12 may be implemented using transmissive projection technology, where the light source is modulated by an optically active material and the backlight is white light, which is typically implemented with a Liquid Crystal Display (LCD) type display having a powerful backlight and high optical density. The illuminator 11 may provide the above-described backlight. The image former 12 may also be implemented using reflection technology, where external light is reflected and modulated by the active material. The image former 12 alone or in combination with the illuminator 11 may also be referred to as a micro-display. The collimatinglens 13 is arranged to receive the divergent display image from the image former 12, to collimate, converge the display image, and to transmit the collimated image towards the in-coupling region 301 of theoptical waveguide 300 for diffraction to thetransfer region 302. In one embodiment, the size of the entrance pupil associated with theoptical waveguide 300 may be the same as or smaller than the size of the exit pupil associated with the image former 12, and may be designed appropriately according to specific needs, and is not limited herein.

In one embodiment, thedisplay engine 10 emits the light beam having the image information associated with the FOV to the coupling-inregion 301, the light beam is coupled to thetransmission region 302 through the coupling-inregion 301, and can be divided into light beams in different directions according to the angle of the light beam diffracted to thetransmission region 302 through the coupling-inregion 301, the light beams in different directions are subjected to total reflection propagation in different waveguide layers of thetransmission region 302 under the action of the angle selection film, and the light beams in different directions totally reflected in the transmission region are combined and exit from the coupling-outregion 310 at the same position of thelight waveguide 300. In the present embodiment, thetransmission region 302 includes afirst substrate 303, a first angleselective film 304, asecond substrate 305, a second angleselective film 306, athird substrate 307, a third angleselective film 308, and afourth substrate 309. Generally, thefirst substrate 303, thesecond substrate 305, thethird substrate 307, and thefourth substrate 309 include optical glass or an optical resin material (e.g., BK-7 glass) having a critical angle of total reflection. Thefirst substrate 303 and the firstangle selection film 304 form a first waveguide layer, thesecond substrate 305 and the secondangle selection film 306 form a second waveguide layer, and thethird substrate 307 and the reflective thirdangle selection film 308 form a third waveguide layer. The structures of the firstangle selection film 304, the secondangle selection film 306, and the thirdangle selection film 308 are determined by the beam diffraction angles of incident beams in different directions.

It should be noted that theoptical waveguide 300 may further include other multilayer waveguide layers, such as two layers, four layers, five layers, etc., and the embodiment is only described with three layers of waveguide layers, but is not limited thereto.

Fig. 4 is a schematic diagram of a light propagation control based on the optical waveguide structure shown in fig. 3. The light beam having a certain FOV emitted from thedisplay engine 10 is diffracted by theincoupling zone 401 and then divided into a first direction light beam, a second direction light beam, a third direction light beam, and a fourth direction light beam according to the difference of the diffraction directions. The angles at which the first direction light beam, the second direction light beam, the third direction light beam, and the fourth direction light beam are incident on thetransfer region 402 need to satisfy the angle selection condition of the angle selection film, and the angle selection film is selectively reflected or transmitted. In the figure, the diffraction angle of the first-direction light beam is not smaller than that of the second-direction light beam, the diffraction angle of the second-direction light beam is not smaller than that of the third-direction light beam, and the diffraction angle of the third-direction light beam is not smaller than that of the fourth-direction light beam.

In this embodiment, when all light beams are diffracted to the transmission region 402 through the incoupling region 401, the first direction light beam, such as the light beam 21, satisfies the angle selection condition of the first angle selection film 404, and after the action of the first angle selection film 404, the light beam 21 is reflected, so that the light beam in the direction propagates in the first waveguide layer and exits the light beam 25 from the outcoupling region 410, and the light beams in the other directions are transmitted into the next waveguide layer because they do not satisfy the angle selection condition of the first angle selection film 404; a light beam in a second direction, such as the light beam 22, satisfies the angle selection condition of the second angle selection film 406, and after the action of the second angle selection film 406, the light beam 22 is reflected, so that the light beam in the direction propagates in the waveguide layer formed by the first waveguide layer and the second waveguide layer, and exits from the coupling-out region 410 as the light beam 25, and the light beams in the other directions are transmitted into a higher layer region because the light beams do not satisfy the angle selection condition of the second angle selection film 406; a third directional light beam, such as the light beam 23, satisfies the angle selection condition of the third angle selection film 408, and after the third angle selection film 408 acts, the light beam 23 is reflected, so that the first waveguide layer, the second waveguide layer and the third waveguide layer of the light beam in the direction propagate through the waveguide layers, and the light beam 25 exits from the coupling-out region 410; the remaining light beams (e.g., light beam 24) do not satisfy the angle selection condition of the third angle selection film 408, and thus are transmitted into the next waveguide layer, and when they satisfy the angle selection condition of the next waveguide layer, they are reflected, propagate between the waveguide layers, and exit through the outcoupling region 410.

In another embodiment, theoptical waveguide 400 may also be configured as a waveguide structure with two, four or more (denoted as N) waveguide layers, and the arrangement is reasonable according to specific requirements, which is not limited herein. It will be appreciated that when arranged as an N-layer waveguide, the corresponding diffracted beam should be an N-direction beam.

It is noted that when theoptical waveguide 400 is provided in two layers, there is only one layer of the angle selection film; when theoptical waveguide 400 includes three or more layers, there are a plurality of (two or more layers of) angle selection films, and the angle selection of the plurality of angle selection films is different.

The optical waveguide formed by one or more layers of angle selection films is arranged, light beams coupled into the waveguide are divided into light beams in multiple directions according to different incident diffraction angles, effective transmission thicknesses of the light beams in different directions are inconsistent through angle selection conditions of the angle selection films, and therefore different propagation period differences of propagation angles are compensated, light propagation regulation is achieved, and propagation period consistency is achieved. Meanwhile, the light rays are uniformly regulated and controlled through transmission, and the emergent positions of the light beams are consistent, so that the optimization of the grating structure of each area of the optical waveguide structure based on the angle selection film is greatly facilitated, and a better display effect is achieved.

The optical waveguide and the display device can be disposed in various electronic devices, including but not limited to wearable devices, such as a head-mounted display device. Head-mounted display devices include, but are not limited to, Augmented Reality (AR) devices or heads-up displays, and the like.

The foregoing is a more detailed description of the present invention, taken in conjunction with the specific/preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. For those skilled in the art to which the invention pertains, a plurality of alternatives or modifications can be made to the described embodiments without departing from the concept of the invention, and these alternatives or modifications should be considered as belonging to the protection scope of the invention.

Claims (10)

1. An optical waveguide, comprising:

the coupling-in area is used for coupling in the light beams in the preset field direction;

a transfer region including N waveguide layers for propagating the light beam coupled in through the coupling-in region, wherein N is greater than or equal to 2;

an outcoupling region for extracting the light beam propagating through the transfer region;

the transmission region is arranged on a light path between the coupling-in region and the coupling-out region, N-1 angle selection films with different angle selections are arranged among the N waveguide layers, and the N-1 angle selection films with different angle selections selectively reflect or transmit the light beams to enable the light beams to be emitted through the same position of the coupling-out region.

2. The optical waveguide of claim 1 wherein said N waveguide layers are each configured to modulate the period of propagation of said optical beam to coincide with the period of propagation of said optical beam.

3. The optical waveguide of claim 1, wherein the coupling-in region and the coupling-out region comprise a diffraction grating or a diffractive optical element.

4. The optical waveguide of claim 1, wherein the coupling-in region and the coupling-out region are disposed on an outer surface and/or an inner surface of the transfer region.

5. The optical waveguide of claim 1, wherein the coupling-in region and the coupling-out region are disposed on the same surface or different surfaces of the transfer region.

6. The optical waveguide of claim 1 wherein said angle selective film is a dielectric film, said dielectric film comprising magnesium fluoride.

7. The optical waveguide of claim 1, wherein the waveguide layer of the transfer region is further provided with a substrate comprising an optical glass or an optical resin material having a critical angle for total reflection.

8. A display device comprising the optical waveguide according to any one of claims 1 to 7.

9. The display device of claim 8, further comprising a display engine for incidence of an incident light beam having a preset field angle to the incoupling region of the light guide.

10. An electronic device characterized by comprising the display device according to claim 8 or 9.

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