CN113050221A - Optical system and near-to-eye display device thereof - Google Patents
Optical system and near-to-eye display device thereof Download PDFInfo
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/122—Basic optical elements, e.g. light-guiding paths
- G02B6/124—Geodesic lenses or integrated gratings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
- G02B27/0101—Head-up displays characterised by optical features
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
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Abstract
The invention relates to an optical system and a near-eye display device thereof, which comprises an optical waveguide and a light angle adjuster, wherein the optical waveguide is provided with a coupling grating and a decoupling device, the decoupling device is provided with a red light decoupling grating, a green light decoupling grating and a blue light decoupling grating, the light angle adjuster is matched with an output image and a refreshing speed of a display, light of each color of three primary colors in the output image is respectively adjusted to enter the coupling grating at different incident angles by a time division method, the light of each color passes through the coupling grating and then advances to the decoupling device in the optical waveguide at respective diffraction angles, and the light of each color is decoupled in the decoupling grating of each corresponding color, so that the light of each color is combined into a larger visual angle in space, and the problem of dispersion can be solved.
Description
Technical Field
The present invention relates to an optical system, and more particularly, to an optical system using a diffractive optical waveguide and a near-eye display device thereof.
Background
Related optical technologies of Virtual Reality (VR) and Augmented Reality (AR) have received much attention in recent years, but have been developing at a considerably fast rate; in addition, the product has diverse application potential in real life, and products or services achieved by virtual reality and augmented reality technology can be seen in the fields of entertainment, medicine, home furnishing, military affairs and the like.
Examples of applications for virtual reality and augmented reality include various types of display devices, such as: Near-Eye Display (NED) or Head-Mounted Display (HMD). The near-eye display device, which is similar to glasses in shape, may also be called glasses type display, video glasses or head-mounted display device, and mainly comprises a carrying portion, and a micro-display and an optical system installed in the carrying portion.
The micro-display is used for providing images for the near-eye display device. The micro display may be a self-luminous Active Device (Active Device) such as a mini Light Emitting Diode (LED), a micro-LED …, or the like, or a liquid crystal display Device requiring an external light source for illumination, such as: transmissive Liquid Crystal displays and reflective Liquid Crystal On Silicon (LCOS) projectors, as well as Digital micro mirror devices (DMD) based On Micro Electro Mechanical Systems (MEMS) technology, which are the core of Digital Light Processing (DLP) and Laser Beam Scanners (LBS) ….
Furthermore, in the optical system of the near-eye display device, in order to transmit and receive the light output from the microdisplay to the eye without loss and leakage during transmission, the light needs to be allowed to travel to the eye by total reflection within the waveguide in the optical system, and the light needs to travel by total reflection within the waveguide, the following two conditions need to be satisfied:
refractive index n of material of transmission medium, i.e. waveguide1It is necessary to have a higher refractive index n than the surrounding medium2；
The angle of incidence of light into the waveguide needs to be greater than the critical angle.
When the micro-display outputs the image in a light state, the waveguide couples the light into its own substrate (e.g., glass), and transmits the light to the front of the eye by means of total reflection. In this process, the waveguide is only responsible for transmitting the image, and generally, no adjustment is made to the image, such as zooming in or out, but only the transmission distance of the image is shortened. This property of the optical waveguide is highly advantageous for the design and aesthetic appearance of the near-eye display device. Because of the waveguide which is a light transmission component, the micro-display and the optical system can be far away from the right front of the near-eye display device and moved to the positions such as the top of the forehead or the side of the near-eye display device, so that the problem that the optical system blocks the external sight line is solved, the weight distribution is more in line with the ergonomics, and the wearing experience of the near-eye display device is improved.
The optical Waveguide may be classified into a Geometric Waveguide (so-called array Waveguide) which implements image output and expansion of an eye movement range (eyebox) by an array mirror stack, and a Diffractive Waveguide (Diffractive Waveguide). The diffraction optical waveguide mainly includes Surface Relief Grating (SRG) manufactured by photolithography and Volume Holographic Grating (VHG) manufactured by Holographic interference technology. However, the geometric optical waveguide has problems such as low yield, low ambient light transmittance, large Form factor, and susceptibility to ghost (ghost image). The waveguide type of the volume holographic grating waveguide has a higher degree of freedom, is thinner and lighter, and is simpler to manufacture, but has a problem of low optical efficiency because the type of the grating is related to the wavelength, so that light with different wavelengths propagates in the waveguide differently (with different diffraction angles), which leads to dispersion (color break, also called rainbow effect), because the period of the grating is fixed, when the light enters the grating, different wavelengths often have corresponding diffraction legs, and the longer the wavelength is, the diffraction angle is increased, so the diffraction angle relationship of the three primary colors is θR(angle of diffraction of Red light) > thetaG(angle of diffraction of green light) > thetaB(diffraction angle of blue light), the path length of light will be different for each total reflection due to the difference of diffraction angle, the total reflection frequency of red light is less than that of green light, and the total reflection frequency of blue light is the most. Because of this difference, when the light transmitted in the conventional single-layer optical waveguide 10 finally encounters the exit grating, blue light is coupled out 3 times (as shown by the solid arrow in fig. 1), green light is coupled out 2 times (as shown by the dotted arrow in fig. 1), and red light is coupled out 1 time(e.g., the central line arrow in fig. 1), which causes the eyes to move to different positions of the eye movement range, the observed RGB color ratio is not uniform, which causes the uneven distribution in the field of view, i.e., the phenomenon of rainbow-like red, green, and blue 3 primary color shadows are observed in the image, resulting in the rainbow effect.
Referring to fig. 2, the conventional method for solving this problem is to couple red, green and blue lights into three layers of optical waveguides 12, 14 and 16, respectively, and the diffraction grating of each layer is optimized for only one color, for example, the first layer of optical waveguide 12 is coupled with the blue light, the second layer of optical waveguide 14 and the third layer of optical waveguide 16, so as to improve the color uniformity at the exit pupil position and reduce the rainbow effect. But since each color output by the microdisplay is also not a single wavelength, there is still a slight rainbow effect present.
This is a problem of color uniformity caused by physical characteristics of the diffraction grating, in other words, the design of the grating is difficult to be compatible with the covered color band and the Field of view (FOV), so how to design the diffraction grating to act on different wavelengths of red, green and blue, and have a larger Field of view is a problem to be solved.
Disclosure of Invention
In view of the problems of the prior art, the present invention is directed to solving the problem of dispersion (or referred to as rainbow effect) of a diffractive optical waveguide in a near-eye display device, and enabling the near-eye display device to have a larger viewing angle.
The invention provides an optical system, including an optical waveguide and a light angle adjuster, wherein a coupling grating is disposed at an in-coupling position of the optical waveguide, a decoupling device is disposed at an out-coupling position of the optical waveguide, the decoupling device includes a red light decoupling grating, a green light decoupling grating, and a blue light decoupling grating, and the red light decoupling grating, the green light decoupling grating, and the blue light decoupling grating have different decoupling angles, respectively. The light angle adjuster adjusts the light of each color of the three primary colors in the output image to enter the coupling grating at different incident angles, and the light of each color advances in the optical waveguide at respective diffraction angles after passing through the coupling grating to be decoupled by the decoupling grating.
The incident angles of the red, green and blue lights of the three primary colors in the output image are related to the diffraction angles of the red, green and blue lights, and the positions of the red, green and blue light decoupling gratings, so that the red, green and blue lights respectively reach the positions of the red, green and blue light decoupling gratings for decoupling.
The red light decoupling grating has a decoupling angle corresponding to the wavelength of red light, the green light decoupling grating has a decoupling angle corresponding to the wavelength of green light, and the blue light decoupling grating has a decoupling angle corresponding to the wavelength of blue light.
The light angle adjuster comprises a liquid crystal box and a light polarization plate, wherein the light polarization plate is arranged on one surface of the liquid crystal box facing the display, and the liquid crystal in the liquid crystal box turns according to the electric field type, so that the light of each color is modulated into different incident angles to enter the coupling grating.
The liquid crystal display device comprises a liquid crystal box, a light polarization plate, an upper electrode layer, a lower electrode layer and a plurality of electrode control areas, wherein the surface of the light polarization plate, which faces the liquid crystal box, is provided with the upper electrode layer and the lower electrode layer, the upper electrode layer is arranged on the lower electrode layer, the upper electrode layer is provided with the plurality of electrode control areas on the lower electrode layer, the electrode control areas are spaced from each other, the lower electrode layer is grounded, and different electric fields generated between the upper electrode layer and the lower electrode layer are enabled to be generated by inputting voltages with different.
The light polarization plate correspondingly controls each electrode control area by a time division method according to the refreshing speed of the display and three primary colors in an output image, so that each electrode control area respectively receives different voltages aiming at different colors of light to generate a corresponding electric field, and the light of each color enters the light guide through adjusting the light angle into respective incident angles by the light angle adjuster, is respectively transmitted in the light guide by respective diffraction angles, and further reaches the position decoupling of the decoupling grating of each color.
The light angle adjuster comprises a liquid crystal box and two light polarization plates, wherein one of the two light polarization plates is arranged at the position of the liquid crystal box facing the display, the other one of the two light polarization plates is arranged at the side of the liquid crystal box facing the optical waveguide, the liquid crystal box comprises two substrates, liquid crystal is arranged between the two substrates, a plurality of first electrode units are arranged on one substrate, and by inputting voltages with different magnitudes to the electrode units, the liquid crystal in the liquid crystal box correspondingly rotates according to the different voltages of the electrode units, so that the light of each color is modulated into different incident angles to enter the coupling grating.
The electrode units are respectively used for receiving different voltages aiming at different colors of light by matching with the refreshing speed of the display and correspondingly inputting different voltages of three primary colors in an output image by a time division method, so that corresponding voltage differences are generated, the light of each color is adjusted into respective incident angles by the light angle adjuster to enter the light guide, and is respectively transmitted in the light guide by respective diffraction angles, and further reaches the position of the decoupling grating of each color for decoupling.
As described above, the light of each color is decoupled by the respective decoupling grating, so that the light efficiency is concentrated without dispersion, and the light of each color is reflected by the respective decoupling grating, so that the light distribution range and angle reflected by the different decoupling gratings are much larger than those of a single decoupling grating, and thus, the field of view (FOV) can be increased, and a larger eye movement range (eyebox) can be combined in space.
Drawings
Fig. 1 is a schematic diagram of light paths of three primary colors in a conventional single-layer volume holographic grating waveguide.
Fig. 2 is a schematic diagram of light paths of three primary colors in a conventional multilayer volume holographic grating waveguide.
Fig. 3 is a schematic diagram of the optical path of red light in the optical system of the present invention.
Fig. 4 is a schematic diagram of the light path of green light in the optical system of the present invention.
Fig. 5 is a schematic diagram of the optical path of blue light in the optical system of the present invention.
Fig. 6 is a schematic diagram of the optical paths of red light, green light and blue light in the optical system of the present invention.
FIG. 7 is a schematic diagram of an electric field pattern of the non-input voltage in each electrode control region according to the first embodiment of the present invention.
FIG. 8 is a schematic diagram of light emitted from the display of FIG. 7 after the light passes through the light angle adjuster.
FIG. 9 is a schematic diagram of an electric field pattern of input voltages of the electrode control regions according to the first embodiment of the present invention.
FIG. 10 is a schematic diagram of light emitted from the display of FIG. 9 when the light of the output image passes through the light angle adjuster.
FIG. 11 is a schematic view of a light angle adjuster according to a second embodiment of the invention.
Fig. 12 is a schematic view of a near-eye display device according to the present invention.
Reference numerals
2: optical waveguide
20: coupled grating
22: decoupling device
220: red light decoupling grating
222: green light decoupling grating
224: blue light decoupling grating
3: light angle regulator
30: liquid crystal box
300: liquid crystal display device
302: substrate
304: electrode unit
3040: a first electrode
3042: second electrode
αR: incident angle of red light
αG: incident angle of green light
αB: incident angle of blue light
4: display device
40: outputting the image
5: light polarizing plate
50: upper electrode layer
52: lower electrode layer
500: electrode control zone
6: spectacle frame
60: picture frame
62: glasses leg
7: optical system
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 3, the present invention is an optical system including an optical waveguide 2 and a light angle adjuster 3, wherein a coupling grating 20 is disposed at an in-coupling position of the optical waveguide 2, a decoupling device 22 is disposed at an out-coupling position of the optical waveguide 2, the decoupling device 22 includes a red decoupling grating 220, a green decoupling grating 222 and a blue decoupling grating 224, the red decoupling grating 220, the green decoupling grating 222 and the blue decoupling grating 224 respectively have different decoupling angles, the decoupling angle of the red decoupling grating 220 corresponds to a wavelength of red light (as shown in fig. 3), the decoupling angle of the green decoupling grating 222 corresponds to a wavelength of green light (as shown in fig. 4), the decoupling angle of the blue decoupling grating 224 corresponds to a wavelength of blue light (as shown in fig. 5), and an incident angle α of the red light is αRGreen light incidence angle alphaGAnd incident angle alpha of blue lightBDepending on the diffraction angles of the red, green and blue light beams in the optical waveguide 2, the positions of the red, green and blue decoupling gratings 220, 222 and 224, the red, green and blue light beams are decoupled from the positions of the red, green and blue decoupling gratings 220, 222 and 224 (as shown in fig. 6).
It should be noted that the positions of the red decoupling grating 220, the green decoupling grating 222 and the blue decoupling grating 224 in fig. 3 to 6 in the decoupler 22 are only illustrative and not limiting, and the red decoupling grating 220. The green light decoupling grating 222 and the blue light decoupling grating 224 must be arranged in the same order as the positions shown in fig. 3-6. Incident angle alpha of red lightRGreen light incidence angle alphaGAnd incident angle alpha of blue lightBThe size and direction of the light source do not need to be equal to the size and direction of the angle drawn in FIGS. 3-6, the diffraction angle of the red, green, and blue light in the light guide 2 does not need to be equal to the size and direction of the angle drawn in FIGS. 3-6, and FIGS. 3-6 are only for showing the incident angle alpha of the red lightRGreen light incidence angle alphaGAnd incident angle alpha of blue lightBThe magnitude or direction of the light beam and the magnitude or direction of the diffraction angles of the red, green and blue light beams in the optical waveguide 2 are not uniform, and reach the positions of the red decoupling grating 220, the green decoupling grating 222 and the blue decoupling grating 224 corresponding to the respective colors.
In the present invention, the light angle adjuster 3 receives the output image 40 outputted from the display 4, and adjusts the red light, the green light and the blue light of the three primary colors in the output image 40 to enter the coupling grating 20 at different incident angles, respectively, and the red light, the green light and the blue light are decoupled by the respective diffraction angles respectively proceeding (for example, totally reflecting) to the positions of the red light decoupling grating 220, the green light decoupling grating 222 and the blue light decoupling grating 224 in the optical waveguide 2, so that the light efficiency is concentrated without dispersion, and the light distribution range and angle of each color after being decoupled by the different decoupling gratings are larger than the light distribution range and angle of all colors after being decoupled by only a single decoupling grating, therefore, compared with the conventional optical system, the field of view (FOV) of the present invention is large and a large eye movement range (eyebox) can be combined in space.
In order to enable the liquid crystal in the light angle adjuster 3 to be turned to different angles, and further enable the red light, the green light and the blue light passing through the light angle adjuster 3 to enter the coupling grating 20 at different incident angles, in an embodiment of the present invention, as shown in fig. 7, the light angle adjuster 3 includes a liquid crystal box 30 and a light polarizer 5, wherein the light polarizer 5 is disposed on a side of the liquid crystal box 30 facing the display 4, and the red light, the green light and the blue light are modulated to different incident angles to enter the coupling grating 20 by controlling the liquid crystal 300 in the liquid crystal box 30 to be turned according to an electric field pattern. Furthermore, the polarizer 5 has an upper electrode layer 50 and a lower electrode layer 52 on a surface facing the liquid crystal cell 30, wherein the lower electrode layer 52 is grounded, the upper electrode layer 50 includes a plurality of electrode control areas 500, each electrode control area 500 is disposed on the lower electrode layer 52, and the electrode control areas 500 are separated from each other by a distance such that the electrode control areas 500 are not connected to each other.
Referring to fig. 8, when the electrode control regions 500 do not receive any voltage and no electric field changes, the liquid crystal 300 in the light angle adjuster 3 does not turn, and the red, green and blue light enters the light guide 2 at the same incident angle. Referring to fig. 9 and 10, when each electrode control area 500 receives a respective input voltage, the upper electrode layer 50 and the lower electrode layer 52 generate a corresponding electric field pattern according to the input voltage, and the liquid crystal 300 is turned according to the electric field pattern, so that the red light, the green light, and the blue light can be modulated into different incident angles to enter the coupling grating 2 according to a rotation angle required by the liquid crystal 300, and the magnitude of the input voltage of each electrode control area 500 is controlled, respectively, so as to achieve the purpose that the red light, the green light, and the blue light are modulated into different incident angles by the light angle adjuster 3 to enter the coupling grating 20.
In the present invention, the electrode control regions 500 are correspondingly inputted with the required voltages by time division method in accordance with the refresh rate of the display 4 and the three primary colors in the output image 40, so that the electrode control regions 500 receive different voltages to generate the electric field patterns corresponding to the red, green and blue light, respectively, and the red, green and blue light passes through the light angle adjuster 3 in the axial direction and enters the light guide 2 at the incident angles of the red, green and blue light.
In order to further understand how to control each electrode control area 500 by the time division method, the refresh rate of the output image 40 of the display 4 is 60Hz as an example, but in the actual implementation of the present invention, the refresh rate of the output image 40 of the display 4 is not limited to 60Hz, and may be 120Hz, 144Hz or higher. The output image 40 of the display 4 outputs red light at 1/60 seconds, green light at 2/60 seconds, blue light at 3/60 seconds, red light at 4/60 seconds, green light at 5/60 seconds, blue light at 6/60 seconds, red light at … 58/60 seconds, green light at 59/60 seconds, and blue light at 60/60 seconds. The electrode control regions 500 form the electric field required for red light at 1/60 seconds, 4/60 seconds … seconds, 58/60 seconds, allowing red light to enter the light guide 2 at the desired angle of incidence. The electrode control regions 500 produce the electric field required for green light at 2/60 seconds, 5/60 seconds … seconds, 59/60 seconds, allowing the green light to enter the light guide 2 at the desired angle of incidence. Further, each electrode control region 500 forms the electric field required for the blue light at 3/60 seconds, 6/60 seconds … seconds and 60/60 seconds, so that the blue light can enter the light guide 2 at a required incident angle. In this way, in the above cycle, the human eye can still see the full-color output image 40 due to the persistence of vision of the human eye, and the red light, the green light, and the blue light of the output image 40 combine a large visual angle (FOV) in the space during the output process. In other words, the time division method outputs the red, green and blue light of the output image 40 in cycles and at average times according to the refresh rate.
In a second embodiment of the present invention, referring to fig. 11, the light angle adjuster 3 includes a liquid crystal cell 30 and two light polarizers 5, wherein one of the two light polarizers 5 is disposed at a position where the liquid crystal cell 30 faces the display 4, the other of the two light polarizers 5 is disposed at a side of the liquid crystal cell 30 facing the light guide 2, the liquid crystal cell 30 includes two substrates 302, a liquid crystal 300 is disposed between the two substrates 302, and a plurality of electrode units 304 are disposed on one of the substrates 302, and by inputting voltages of different magnitudes to the electrode units 304, the liquid crystal 300 in the liquid crystal cell 30 is rotated according to the voltage difference of the electrode units 304, so that the light of each color is modulated into different incident angles to enter the coupling grating 20.
In the second embodiment of the present invention, the electrode units 340 correspondingly input voltages with different magnitudes by a time division method in accordance with the refresh rate of the display 4 and the three primary colors in the output image, so that the electrode units 304 respectively receive different voltages for the light with different colors to generate corresponding voltage differences, and the light with each color is adjusted by the light angle adjuster 3 to have a respective incident angle, enters the optical waveguide 2, and is respectively transmitted in the optical waveguide 2 at a respective diffraction angle, thereby reaching the position of the decoupling grating of each color for decoupling.
In the second embodiment of the present invention, each electrode unit 304 is respectively provided with a first electrode 3040 and a second electrode 3042, wherein the first electrode 3400 is disposed at a position where one substrate 302 faces the other substrate 302, the second electrode 3040 is disposed at a position where one substrate 302 faces the other substrate 302, and a space is provided between the first electrode 3042 and the second electrode 3402, and the liquid crystal 300 is a positive liquid crystal, an optical axis of the liquid crystal 300 is parallel to the substrates 302, before a voltage is applied to the first electrode 3040 and the second electrode 3042, the liquid crystal 300 does not rotate about the optical axis, light of each color cannot pass through the light polarization plate 5 at a side of the liquid crystal cell 30 facing the light guide 2, and after a voltage is applied to the first electrode 3040 and the second electrode 3042, the liquid crystal 300 can rotate about the optical axis, and different voltages are applied to the first electrode 3040 and the second electrode 3042 to change an electric field of the liquid crystal 300, thereby controlling the angle of the light angle adjuster 3 and opening the viewing angle to allow light to pass through the light angle adjuster 3 to reach the light guide 2.
Referring to fig. 12, the present invention is a near-eye display device, including a frame 6 and the optical system 7, wherein the frame 6 includes a frame 60 and a set of legs 62, the set of legs 62 is disposed on two sides of the frame 60, and the optical system 7 is disposed in the frame 60, so that the near-eye display device can be used as an augmented reality display device, and can see real images of the real world and project virtual images to human eyes through the optical system.
In still other embodiments, the display may include a single Augmented Reality (AR) or Virtual Reality (VR) display assembly for both eyes, and an optical switching device, not shown, may be coupled to each display assembly to output a frame of image to one of the display assemblies in a time sequence such that the user's left and right eyes are displayed in a left-eye-frame, right-eye-frame cycle, respectively, in sequence. Since the display speed of the image is fast enough, in other words, with a frame rate fast enough, the flicker is not seen by the eyes of the user, and the image is stabilized.
In summary, the light angle adjuster 3 correspondingly controls each electrode control area 500 or each electrode unit 340 by a time division method in accordance with the refresh rate of the display 4 and the three primary colors in the output image 40, so that each electrode control area 500 or each electrode unit 340 respectively receives different voltages for different colors of light to generate corresponding electric fields, and the light of each color enters the optical waveguide 2 at the incident angle of the corresponding color after passing through the light angle adjuster 3, thereby solving the dispersion or rainbow effect of the conventional volume holographic grating waveguide, and combining a larger visual angle in space.
The above detailed description is specific to possible embodiments of the present invention, but the above embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention are intended to be included within the scope of the present invention.
Claims (20)
1. An optical system, comprising:
an optical waveguide, comprising:
the coupling grating is arranged at the coupling-in position of the optical waveguide; and
the optical waveguide coupler comprises an optical waveguide, a decoupling device and a decoupling device, wherein the optical waveguide is provided with an optical waveguide, the decoupling device is arranged at an out-coupling position of the optical waveguide and comprises a red light decoupling grating, a green light decoupling grating and a blue light decoupling grating, and the red light decoupling grating, the green light decoupling grating and the blue light decoupling grating respectively have different decoupling angles; and
a light angle adjuster, one side of the light angle adjuster is arranged at a relative coupling-in position, the other side of the light angle adjuster receives an output image of the display, and red light, green light and blue light in the output image are respectively adjusted to enter the light guide at different incidence angles;
after passing through the coupling grating, the red light, the green light, and the blue light respectively move to the red light decoupling grating, the green light decoupling grating, and the blue light decoupling grating in the optical waveguide at respective diffraction angles, so that the red light is decoupled by the red light decoupling grating, the green light is decoupled by the green light decoupling grating, and the blue light is decoupled by the blue light decoupling grating.
2. The optical system of claim 1, wherein an angle of incidence of the red light, an angle of incidence of the green light, and an angle of incidence of the blue light are related to the angles of diffraction of the red, green, and blue light and positions of the red, green, and blue decoupling gratings.
3. The optical system of claim 1, wherein the decoupling angle of the red decoupling grating corresponds to a wavelength of the red light, the decoupling angle of the green decoupling grating corresponds to a wavelength of the green light, and the decoupling angle of the blue decoupling grating corresponds to a wavelength of the blue light.
4. The optical system of claim 1, wherein the ray angle adjuster comprises:
the liquid crystal box is arranged between the optical waveguide and the display, and liquid crystal is arranged in the liquid crystal box;
the light polarization plate is arranged on one surface of the liquid crystal box, which faces the display;
the liquid crystal rotates according to different electric fields, and the red light, the green light and the blue light are modulated into a required incident angle through the light angle adjuster and enter the coupling grating.
5. The optical system of claim 4, wherein the ray angle adjuster further comprises:
the lower electrode layer is arranged on one surface of the light polarization plate and is grounded; and
the upper electrode layer is arranged on one surface of the lower electrode layer and comprises a plurality of electrode control areas, the adjacent electrode control areas are respectively spaced, and voltages with different magnitudes are input into the electrode control areas, namely different electric fields are generated.
6. The optical system as claimed in claim 5, wherein each of the electrode control regions is adapted to match a refresh rate of the display and three primary colors in an output image to respectively input different voltages, so that each of the electrode control regions receives different voltages for the red light, the green light and the blue light respectively to generate corresponding electric fields, and the red light, the green light and the blue light axially pass through the light angle adjuster and enter the light guide at different incident angles.
7. The optical system of claim 6, wherein the time division method cycles and averages the number of times an output image is output with red, green, and blue light according to the refresh rate.
8. The optical system of claim 6, wherein the ray angle adjuster comprises:
the liquid crystal box is arranged between the optical waveguide and the display and comprises two substrates, liquid crystal is arranged between the two substrates, and a plurality of electrode units are arranged on one substrate; and
two light polarization plates, one of which is arranged at the position of the liquid crystal box facing the display, and the other of which is arranged at the side of the liquid crystal box facing the light guide;
the liquid crystal in the liquid crystal cell rotates by different angles according to different voltage differences of the electrode units, so that the red light, the green light and the blue light are modulated into required incident angles through the light angle adjuster and enter the coupling grating.
9. The optical system of claim 8, wherein each of the electrode units comprises:
a first electrode provided at a position where one of the substrates faces the other substrate; and
a second electrode provided at a position where one of the substrates faces the other substrate; and the first electrode and the second electrode have a space therebetween;
the optical axis of the liquid crystal is parallel to the two substrates;
before no voltage is applied to the first electrode and the second electrode, the liquid crystal cannot rotate, and after the voltage is applied to the first electrode and the second electrode, the liquid crystal correspondingly rotates.
10. The optical system as claimed in claim 11, wherein the first electrode and the second electrode are respectively controlled to input different voltages by time division in accordance with the refresh rate of the display and the three primary colors in the output image, so that the red light, the green light, and the blue light respectively enter the light guide at different incident angles after passing through the light angle adjuster.
11. The optical system of claim 10, wherein the time division method cycles and averages the number of times an output image is output with red, green, and blue light according to the refresh rate.
12. A near-eye display device, comprising:
the spectacle frame comprises a spectacle frame and a group of spectacle legs, and the group of spectacle legs are arranged on two sides of the spectacle frame;
an optical system according to claim 1, provided in the frame.
13. The near-eye display device of claim 12, wherein an angle of incidence of the red light, an angle of incidence of the green light, and an angle of incidence of the blue light are related to the angles of diffraction of the red, green, and blue light and positions of the red, green, and blue decoupling gratings.
14. The near-eye display device of claim 12, wherein the decoupling angle of the red decoupling grating corresponds to a wavelength of the red light, the decoupling angle of the green decoupling grating corresponds to a wavelength of the green light, and the decoupling angle of the blue decoupling grating corresponds to a wavelength of the blue light.
15. The near-eye display device of claim 12, wherein the ray angle adjuster comprises:
the liquid crystal box is arranged between the optical waveguide and the display, and liquid crystal is arranged in the liquid crystal box;
the light polarization plate is arranged on one surface of the liquid crystal box, which faces the display;
the liquid crystal rotates according to different electric fields, and the red light, the green light and the blue light are modulated into a required incident angle through the light angle adjuster and enter the coupling grating.
16. The near-eye display device of claim 15, wherein the ray angle adjuster further comprises:
the lower electrode layer is arranged on one surface of the light polarization plate and is grounded; and
the upper electrode layer is arranged on one surface of the lower electrode layer and comprises a plurality of electrode control areas, the adjacent electrode control areas are respectively spaced, and voltages with different magnitudes are input into the electrode control areas, namely different electric fields are generated.
17. The near-to-eye display device of claim 16 wherein the light polarizer controls the electrode control regions in time division in accordance with refresh rate of the display and three primary colors in the output image, each electrode control region receiving different voltages for the red, green, and blue light, respectively, to generate corresponding electric fields, the red, green, and blue light entering the light guide at different angles of incidence axially through the light angle adjuster.
18. The near-eye display device of claim 12, wherein the ray angle adjuster comprises:
a liquid crystal cell disposed between the optical waveguide and the display, the liquid crystal cell including two substrates, liquid crystal disposed between the two substrates, and a plurality of electrode units disposed on one of the substrates; and
two light polarizers, one of which is arranged at the position of the liquid crystal box facing the display, and the other of which is arranged at the side of the liquid crystal box facing the light guide;
the liquid crystal in the liquid crystal cell rotates by different angles according to different voltage differences of the electrode units, so that the red light, the green light and the blue light are modulated into required incident angles through the light angle adjuster and enter the coupling grating.
19. The near-eye display device of claim 18, wherein each of the electrode units comprises:
a first electrode provided at a position where one of the substrates faces the other substrate;
a second electrode provided at a position where one of the substrates faces the other substrate with a space therebetween;
the optical axis of the liquid crystal is parallel to the two substrates;
before no voltage is applied to the first electrode and the second electrode, the liquid crystal cannot rotate, and after the voltage is applied to the first electrode and the second electrode, the liquid crystal correspondingly rotates.
20. The near-to-eye display device of claim 19, wherein the first electrode and the second electrode cooperate with refresh rate of the display and three primary colors in an output image to correspondingly control input of different voltages, so that the red light, the green light, and the blue light enter the light guide at different incident angles after passing through the light angle adjuster.
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| TW202240221A (en) | 2022-10-16 |
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