CN112014971A - Augmented reality display assembly and augmented reality display device with same - Google Patents
Augmented reality display assembly and augmented reality display device with same Download PDFInfo
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- 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
- G02B27/017—Head mounted
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Abstract
The invention provides an augmented reality display component, which comprises an image unit, an ocular unit and a refraction unit, wherein the refraction unit comprises a first optical switch and a first birefringent crystal, the first optical switch is positioned between the image unit and the first birefringent crystal, the refraction unit also comprises a second birefringent crystal and a first phase retarder, the phase delay of the first phase retarder is pi/2 and the first phase retarder is arranged between the first birefringent crystal and the second birefringent crystal. The invention also provides display equipment applying the augmented reality display component. The invention realizes a multi-depth-of-field spherical imaging image output mode by utilizing the first birefringent crystal, the second birefringent crystal and the first phase delayer arranged between the first birefringent crystal and the second birefringent crystal, can ensure that the quality of image output is maintained in a high-quality output mode of a spherical surface, has less image distortion and improved imaging definition, and has wide application prospect and extremely high economic value.
Description
Technical Field
The invention relates to the technical field of augmented reality, in particular to an augmented reality display assembly and augmented reality display equipment with the same.
Background
The augmented Reality technology (AR) can integrate a virtual world and a real world on a screen, achieves sensory experience exceeding and increasing Reality by real-time superposition of multi-sensory simulation information such as vision, hearing and the like and real environment information, and has a very wide application prospect in various fields such as entertainment, medical treatment, military and the like. The augmented reality display component is a core component of the whole system and directly displays the superposed image of the simulation information and the environmental information to a user. The existing augmented reality display component ensures the spherical high-quality display of images on the basis of multi-depth-of-field image display by using two birefringent crystals, but the existing augmented reality display component is easy to generate image dislocation when multi-depth-of-field display is realized, so that the definition of image display and the experience degree of a user are easily reduced.
Disclosure of Invention
In view of the foregoing, there is a need for an improved augmented reality display assembly and an augmented reality display device having the same, which can overcome the problem of image misalignment in multi-depth display, and has a wide application prospect and excellent economic benefits.
The invention provides an augmented reality display assembly, which comprises an image unit, an ocular unit and a refraction unit arranged between the image unit and the ocular unit, wherein the refraction unit comprises a first optical switch, a first birefringent crystal, a first phase retarder and a second birefringent crystal, the first optical switch is arranged between the image unit and the first birefringent crystal, the phase delay of the first phase retarder is pi/2 and is arranged between the first birefringent crystal and the second birefringent crystal;
the refraction unit further comprises a first polarizer, a third birefringent crystal and a fourth birefringent crystal, the first polarizer is arranged between the image unit and the first optical switch, the third birefringent crystal is arranged between the first birefringent crystal and the first phase retarder, and the fourth birefringent crystal is arranged between the second birefringent crystal and the eyepiece unit;
naming the polarization direction of linearly polarized light output by the first polarizer as a first direction, naming the direction vertical to the first direction as a second direction, and naming the first birefringent crystal as a birefringent crystalThe crystal optical axis of the body and the crystal optical axis of the third birefringent crystal are both perpendicular to the second direction, and the crystal optical axis of the first birefringent crystal forms theta relative to the first direction1An angle, a crystal optic axis of the third birefringent crystal forming-theta with respect to the first direction1An angle;
the crystal optical axis of the second birefringent crystal and the crystal optical axis of the fourth birefringent crystal are both perpendicular to the first direction, and the crystal optical axis of the second birefringent crystal forms theta relative to the second direction2An angle, a crystal optic axis of the fourth birefringent crystal forming- θ with respect to the second direction2And (4) an angle.
Further, the theta1Is 45 degrees; and/or the presence of a catalyst in the reaction mixture,
theta is described2Is 45 degrees.
Further, the refraction unit further includes a second optical switch, the image unit includes a polarization reflector, a second phase retarder, and an optical coupler, the second optical switch is disposed between the fourth birefringent crystal and the polarization reflector, and the second phase retarder is disposed between the polarization reflector and the optical coupler and delays a phase of the polarized light transmitted between the polarization reflector and the optical coupler.
Further, the phase delay of the phase delayer is pi/4.
Further, the refraction unit further comprises a second polarizer, and the second polarizer is arranged between the second optical switch and the polarization reflector.
Further, the first polarizer is a polarizer; and/or the presence of a catalyst in the reaction mixture,
the second polarizer is a polarizing plate.
Further, the brightness of the image unit is 5000 nits or more; and/or the presence of a catalyst in the reaction mixture,
the refresh rate of the picture cells is above 120 Hz.
Further, the response time of the optical switch is less than 10 milliseconds; and/or the presence of a catalyst in the reaction mixture,
the light transmittance of the optical switch is greater than 90%.
Further, the resolution of the image unit is 1080P or more.
The invention also provides augmented reality display equipment which comprises an augmented reality display component, wherein the augmented reality display component is any one of the augmented reality display components.
According to the invention, the images on different birefringent crystal units are symmetrically distributed by adjusting the optical axis positions of the first birefringent crystal, the second birefringent crystal, the third birefringent crystal and the fourth birefringent crystal, so that the superposed images can be kept consistent, thereby eliminating image dislocation, improving the definition of the images, and having wide application prospect and extremely high economic value.
Drawings
FIG. 1 is a schematic diagram of an augmented reality display assembly according to an embodiment of the present invention;
FIG. 2 is a schematic view of the optical path of the eyepiece unit after adding a compensation surface;
FIG. 3 is a graph showing an MTF curve for an image at a first depth of field;
FIG. 4 is a distortion mesh showing an image at a first depth of field;
FIG. 5 is a graph showing an MTF curve for an image at a second depth of field;
FIG. 6 is a distortion mesh showing an image at a second depth of field;
FIG. 7 is a schematic diagram of an optical path of the first birefringent crystal shown in FIG. 1;
FIG. 8 is a schematic diagram of the optical path of the second birefringent crystal shown in FIG. 1;
FIG. 9 is a schematic optical path diagram of the first phase retarder shown in FIG. 1;
FIG. 10 is a schematic diagram of optical paths of the first birefringent crystal and the third birefringent crystal shown in FIG. 1;
FIG. 11 is a schematic diagram of the optical paths of the second birefringent crystal and the fourth birefringent crystal shown in FIG. 1;
fig. 12 is a schematic structural diagram of an augmented reality display assembly according to another embodiment of the present invention.
Description of the main elements
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It will be understood that when an element is referred to as being "mounted on" another element, it can be directly mounted on the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an augmented reality display assembly 100 according to an embodiment of the invention. The augmented reality display assembly 100 is for viewing by a user for displaying image information projected into the user's eyes.
In this embodiment, the augmented reality display module 100 is applied to wearable augmented reality glasses (not shown), the augmented reality display module 100 serves as a lens of the augmented reality glasses, and a user observes virtual environment information and real environment information by wearing the augmented reality glasses and observing the augmented reality display module 100.
It is understood that in other embodiments, the augmented reality display assembly 100 may be used in other devices such as wearable helmets, as long as the augmented reality display assembly 100 is perceived and observed by the user.
The augmented reality display assembly 100 includes an image unit 10, an eyepiece unit 20, and a refraction unit 30, the refraction unit 30 being located between the image unit 10 and the eyepiece unit 20; the image unit 10 is used for displaying image information for a user to observe, the eyepiece unit 20 is used for converging image light refracted by the refraction unit 30 and transmitting the image light to human eyes for imaging, and the refraction unit 30 is used for selectively refracting the image light provided by the image unit 10.
The image light provided by the image unit 10 changes its polarization direction after being selectively refracted by the refraction unit 30, and is converged at different positions after being converged by the ocular unit 20, thereby forming different depths of field.
In particular, the image unit 10 is a display, which may be a CRT display, an LCD display, a PDP display or an OLED display.
In the present embodiment, in consideration of comprehensive performance and cost advantages, the sony OLED screen ECX337A display is used as the image unit 10 in the present embodiment, the display is a microdisplay, the diagonal length is only 0.5 inch, the resolution reaches 1280 × 960, the product competitiveness is better, and the user experience is relatively better.
It is understood that in other embodiments, the image unit 10 may also be selected to have a display other than the sony OLED screen ECX337A display, and the invention is not limited to the specific type of display used in the image unit 10, nor the specific type of display used in the image unit 10, as long as the display used in the image unit 10 can normally output the ambient image information and the virtual image information.
The eyepiece unit 20 is positioned between the user's eye and the image unit 10, and the eyepiece unit 20 may be disposed obliquely with respect to the image unit 10 as necessary to smoothly introduce image information to the user's eye.
It is to be understood that the eyepiece unit 20 may employ either a positive type eyepiece or other types of eyepieces other than the positive type eyepiece, such as a negative type eyepiece; the number of eyepieces included in the eyepiece unit 20 may be one or plural.
The refraction unit 30 includes a first polarizer 31, a first optical switch 32, and a first birefringent crystal 33, the first polarizer 31 is disposed between the image unit 10 and the first optical switch 32, and the first birefringent crystal 33 is disposed between the first optical switch 32 and the eyepiece unit 20.
The first polarizer 31 is used for converting image light displayed by the image unit 10 from natural light to linearly polarized light, and the first optical switch 32 is used for adjusting the polarization direction of the linearly polarized light, so that the linearly polarized light emitted by the image unit 10 has different polarization directions; the first birefringent crystal 33 is used to refract the linearly polarized light transmitted from the first optical switch 32, so that the linearly polarized light with different polarization directions has different refraction directions.
The natural light including image information emitted from the image unit 10 is converted into linearly polarized light by the polarization of the first polarizer 31, and then different polarization directions are formed under the adjustment of the first optical switch 32, and finally, a dual-depth-of-field image display is formed under the different refraction effects of the first birefringent crystal 33 on the polarized light with different polarization directions.
Specifically, the first polarizer 31 can convert light rays into polarized light in a natural light state, which utilizes anisotropy of optical properties of a specific material to realize polarization of natural light.
In the present embodiment, the first polarizer 31 polarizes natural light including image information emitted from the image unit 10 using a polarizing plate, and the first polarizer 31 may use a microcrystalline polarizing plate such as a tourmaline wafer or a molecular polarizing plate such as a wire grid polarizing plate.
It is understood that in other embodiments, the first polarizer 31 may also be a polarizer of other types besides a polarizer, such as a polarization splitting prism, as long as the polarizer can polarize the image information.
The first optical switch 32 is connected to the first polarizer 31, and is used for adjusting the polarization direction of the optical signal output by the first polarizer 31. When the first optical switch 32 is turned on, the first optical switch 32 acts on the first polarizer 31; when the first optical switch 32 is turned off, the first optical switch 32 has no regulating effect on the optical signal output from the first polarizer 31.
As far as the structure of the first optical switch 32 itself is concerned, it may adopt a conventional structure. In the present embodiment, the first optical switch 32 is a liquid crystal light valve; preferably, the response time of the first optical switch 32 is set to 10 milliseconds or less, and the light transmittance of the first optical switch 32 is set to a range greater than 90%.
It is understood that in other embodiments, the first optical switch 32 may also adopt other types of optical switching elements such as an electro-optical switch, a thermo-optical switch, an acousto-optical switch, a micro-mechanical optical switch, and a conventional mechanical optical switch, as long as the first optical switch 32 of the type can realize the direction adjustment of the first polarizer 31; the response time and the transmittance of the first optical switch 32 can be selected according to actual conditions, for example, the response time of the first optical switch 32 is set to be more than 10 ms, and the transmittance of the first optical switch 32 is set to be less than 90%.
The first birefringent crystal 33 is located on the optical path between the first optical switch 32 and the eyepiece unit 20, and is used for refracting the polarized light; the first birefringent crystal 33 has different refractive indexes for linearly polarized light with different polarization directions, and the interaction between the first birefringent crystal 33 and the first optical switch 32 enables the acted image light to have different transmission directions.
In the present embodiment, the first birefringent crystal 33 is a birefringent crystal prism; the first birefringent crystal 33 adopts a birefringent crystal prism, so that the incident surface of the light on the birefringent crystal prism and the optical axis and the emergent surface of the birefringent crystal prism are parallel to each other, only the refractive indexes of linearly polarized light in different polarization directions are different when the linearly polarized light passes through the first birefringent crystal 33, the principal light is still in a state of superposition and non-dislocation, and no additional aberration is generated.
Further, the refractive index of the first birefringent crystal 33 is 1.6585 for O light and 1.4865 for E light.
It is understood that in other embodiments, the first birefringent crystal 33 may have other shapes besides the birefringent crystal prism, as long as the shape and type of the first birefringent crystal 33 can refract the linearly polarized light adjusted by the first optical switch 32; the first birefringent crystal 33 may have a refractive index other than the above refractive index for light of different polarization (e.g., O light or E light), as long as the refractive index of the first birefringent crystal 33 is different for light of different polarization directions.
In practical use, considering that the first optical switch 32 needs to continuously switch its on-off state, the first optical switch 32 preferably has a high response frequency, so that the first optical switch 32 has a sufficient response speed to switch its on-off state and adapt to different display requirements of the image unit 10.
The display principle of the augmented reality display assembly 100 with multiple depths of field is briefly explained as follows:
after passing through the first polarizer 31 in the refraction unit 30, the image light generated by the image unit 10 only retains linearly polarized light (such as ordinary light, abbreviated as O light) in a certain characteristic direction; when the first optical switch 32 is turned on, the linearly polarized light (O light) is converted into linearly polarized light (e.g. extraordinary light, abbreviated as E light) in another polarization direction by the adjustment of the first optical switch 32. When the first optical switch 32 is turned off, the first optical switch 32 does not change the polarization direction of the linearly polarized light, and the linearly polarized light (O light) is directly incident into the first birefringent crystal 33;
the first birefringent crystal 33 has different refractive indexes for linearly polarized light in different directions; when the first optical switch 32 is turned on, the first birefringent crystal 33 refracts the O light at a first refraction angle, and the image light in the form of the O light is converged to human eyes after passing through the convergence function of the eyepiece unit 20, so as to obtain an image which can be observed by a user and has a first depth of field; when the first optical switch 32 is turned off, the first birefringent crystal 33 refracts the E light at the second refraction angle, and the image light in the form of the E light is converged to the human eyes after passing through the converging action of the eyepiece unit 20, so as to obtain an image which can be observed by the user and has the second depth of field, thereby completing the display process of the augmented reality display assembly 100 with the double depth of field.
Further, when the first optical switch 32 is continuously refreshed at a proper frequency, the depth of field perceived by the human eye may be between the first depth of field and the second depth of field, thereby forming a controllable adjustment of the optical parameter of the depth of field over the first depth of field and the second depth of field.
The present invention is not limited to the first optical switch 32 that can adjust the direction of the O light to the E light. It is understood that in other embodiments, the first optical switch 32 may also achieve the adjustment of the direction of the E light to the direction of the O light.
According to the augmented reality display assembly 100 provided by the invention, the first polarizer 31, the first optical switch 32 and the first birefringent crystal 33 are arranged between the image unit 10 and the eyepiece unit 20, and images with different depths of field are formed by using different refraction effects of the first birefringent crystal 33 on polarized light in different polarization directions, so that virtual information with any depth can be presented, the conflict of vergence adjustment is solved, the user experience degree is improved, the observation habit of human eyes can be better fitted, adverse reactions such as fatigue, nausea and vomiting after long-term observation of a user can be avoided, and the augmented reality display assembly has a wide application prospect.
In an embodiment of the present invention, the refraction unit 30 further includes a projection unit 34, the projection unit 34 is located between the first birefringent crystal 33 and the eyepiece unit 20, the projection unit 34 is configured to transmit the linearly polarized light transmitted by the first birefringent crystal 33 into an enlarged relay real image, and the projection unit 34 uses its relay enlargement to enable the image signal output by the refraction unit 30 to be transmitted to the eyepiece unit 20 more clearly, so that the transmission loss between the refraction unit 30 and the eyepiece unit 20 is reduced, and image transmission over a longer distance can be achieved.
Further, the projection ratio of the projection unit 34 is preferably 1.6 or less, so as to reduce the compactness of the projection unit, effectively reduce the spatial dimension of the whole assembly and reduce the optical path space, and leave more room for industrial design, making it more ergonomic.
In this embodiment, the projection unit 34 includes four lenses, and the eyepiece unit 20 includes two half-lenses. The data of the equivalent optical path are shown in table 1:
TABLE 1 equivalent light path data sheet
Referring to fig. 2, fig. 2 is a schematic diagram of an optical path after the eyepiece unit 20 is added with a compensation surface. The effect of adding the compensation surface to the eyepiece unit 20 is to allow the human eye to view the real world through the eyepiece unit without distortion of the real world picture.
Referring to fig. 3 to 6 together, fig. 3 is a graph showing an MTF curve of an image at a first depth of field, fig. 4 is a graph showing a distortion mesh of the image at the first depth of field, fig. 5 is a graph showing an MTF curve of an image at a second depth of field, and fig. 6 is a graph showing a distortion mesh of the image at the second depth of field.
In the present embodiment, the exit pupil diameter is 10mm, the exit pupil distance is 18mm, and the full field angle is 50 degrees. Excellent imaging quality is obtained at the first depth and the second depth, the maximum field distortion is less than 0.2%, the MTF (Modulation Transfer Function) of the maximum field at the cutoff frequency of 30lp/mm is larger than 0.4, the MTF value of the maximum field at the cutoff frequency of 30lp/mm at the second depth is more than 0.6, and excellent light field display effect can be obtained.
In an embodiment of the present invention, the augmented reality display assembly 100 is further provided with a control unit (not shown), the control unit is communicatively connected to the first optical switch 32 and the image unit 10 through a medium such as a wire, and the control unit is configured to synchronously control the operation states of the first optical switch 32 and the image unit 10, and control the on/off of the first optical switch 32 according to the depth of field required to be displayed by the image unit 10. The control unit is integrated inside the augmented reality display assembly 100, so that the integration level of the whole system can be improved, and the control function of the whole system can be realized.
It is understood that in other embodiments, the control unit may be disposed outside the augmented reality display assembly 100, that is, the control unit is disposed outside the augmented reality display assembly 100 as an environmental element, as long as the control unit can be communicatively connected with the first light switch 32 and the image unit 10 and cooperatively control the operation states of the first light switch 32 and the image unit 10.
In one embodiment of the present invention, in order to improve the quality of image display, the resolution of the image unit 10 is preferably 1080P or more, and the luminance of the image unit 10 is preferably 5000 nit (nit) or more. The resolution and brightness of the image unit 10 are set to be high, which is helpful for improving the reality of image information display and the experience of a user, so that the fidelity of the virtual image information superposed on the real image information is higher.
In one embodiment of the present invention, in order to guarantee the user experience and allow for the image display of dual depth of field, the refresh rate of the image unit 10 is 120Hz or more (twice or more of 60Hz for single depth of field) so that the user does not have a sense of flicker when viewing; and/or the presence of a catalyst in the reaction mixture,
the extinction ratio of the first polarizer 31 is 10000:1 or more, so that the polarized light polarized by the first polarizer 31 does not have o light and e light at the same time, thereby ensuring that the image observed by the user through the eyepiece unit 20 does not have two depths at the same time, avoiding image crosstalk and improving the imaging quality.
In one embodiment of the present invention, in order to reduce the thickness of the first birefringent crystal 33, the refractive index difference of the first birefringent crystal 33 for o-light or e-light is preferably greater than 0.2, so as to reduce the requirement for the thickness of the first birefringent crystal 33 during refraction, and further reduce the system load.
In one embodiment of the present invention, in order to improve the field of vision of the user, the eyepiece unit 30 of the present invention includes a lens 21, the lens 21 is an aspherical mirror, and the surface equation thereof is:
wherein c is the curvature at the vertex of the curved surface; k is the conic constant of the surface, AiIs the i-order aspheric coefficient of the curved surface.
The lens 21 applied in the invention has the advantages of large exit pupil diameter, long exit pupil distance and wide field angle, the large exit pupil diameter can meet the condition of strabismus when a user wears the lens, the long exit pupil distance can meet the use of a myopia lens and a far vision lens wearer, and the wide field angle can present virtual information more truly, so that the virtual information and the real world are better integrated. According to experimental measurement, the angle of view of the lens 21 applied in the present invention can reach 50 °, and the lens has a wider field of view and better user experience.
Certainly, the augmented reality display component 100 may further be provided with a plurality of functional elements to achieve improvement of user experience, for example, an Inertial Measurement Unit (IMU) may be further integrated on the augmented reality display component 100, and the control unit controls the Inertial measurement unit to detect the pose of the whole machine, so as to further improve the user experience.
When the conventional augmented reality display component utilizes the first birefringent crystal 33 to realize multi-depth-of-field image display, the adjustment rules of the birefringent crystal to different linearly polarized light are different, so that the imaging quality of the birefringent crystal during image display is difficult to ensure simultaneously.
For example, the refractive index of the birefringent crystal to O light does not change with the change of the incident angle of the O light, and the refractive index of the birefringent crystal to O light is constant, so that the image forming effect of a "spherical mirror" is presented when an image is displayed; the refractive index of the birefringent crystal to the E light changes along with the change of the incident angle of the E light, the refractive indexes of the birefringent crystal at the sagittal plane and the meridional plane are different, and the imaging effect of a cylindrical mirror is realized during image display. This results in different imaging effects at different depths of field, and the user may switch back and forth between different images with different imaging effects when observing, which affects the normal observation of the images.
The augmented reality display module 100 provided by the invention has the advantages that the imaging effects at different depths are kept consistent by arranging the two birefringent crystals and arranging the phase retarder, so that the problem of image quality reduction caused by adopting a single birefringent crystal is solved.
Specifically, the refractive unit 30 further includes a second birefringent crystal 35 and a first phase retarder 36, the first phase retarder 36 is located between the first birefringent crystal 33 and the second birefringent crystal 35, and the second birefringent crystal 35 is located between the first phase retarder 36 and the eyepiece unit 20. The first phase retarder 36 has a phase retardation of pi/2, and serves to convert the linearly polarized light into linearly polarized light perpendicular to the original vibration direction.
When the first optical switch 32 is turned off, the linearly polarized light formed by the polarizer 31 after polarization is not converted by the first optical switch 32, and at this time, the linearly polarized light in the initial state forms an output mode of "spherical imaging" through the first birefringent crystal 33; the polarization direction of the linearly polarized light after passing through the first phase retarder 36 is vertical to the initial state, and an output mode of spherical imaging is still formed through the second birefringent crystal 35; in general, the refractive element 30 forms an output mode of "spherical imaging" after the first optical switch 32 is turned off;
after the first optical switch 32 is turned on, linearly polarized light formed after the polarizer 31 performs a polarization function is converted by the first optical switch 32, and then the linearly polarized light after being converted forms an output mode of cylindrical imaging through the first birefringent crystal 33; the linearly polarized light is converted into linearly polarized light with the same vibration direction as the initial state through the first phase retarder 36, and then the linearly polarized light still forms an output mode of cylindrical imaging through the second birefringent crystal 35, but cylindrical surfaces formed by the first birefringent crystal 33 and the second birefringent crystal 35 are mutually vertical; in general, the refractive element 30 forms an output mode of "spherical imaging" after the first optical switch 32 is turned on.
Referring to fig. 7 to 9 together, fig. 7 is a schematic optical path diagram of the first birefringent crystal 33 shown in fig. 1, fig. 8 is a schematic optical path diagram of the second birefringent crystal 35 shown in fig. 1, and fig. 9 is a schematic optical path diagram of the first phase retarder 36 shown in fig. 1.
Light entering the first birefringent crystal 33 passes through the first birefringent crystal 33 along the propagation direction 301; the polarization direction of the linearly polarized light polarized by the first polarizer 31 is named as a first direction 302, the direction perpendicular to the first direction 302 is named as a second direction 303, and the crystal optical axis 331 of the first birefringent crystal 33 is set to be located in the plane formed by the propagation direction 301 and the first direction 302, that is, the crystal optical axis 333 of the first birefringent crystal 33 is preferably perpendicular to the second direction 303.
Light entering the second birefringent crystal 35 passes through the second birefringent crystal 35 along the propagation direction 301; the polarization direction of the linearly polarized light after polarization by the first polarizer 31 is named as a first direction 302, the direction perpendicular to the first direction 302 is named as a second direction 303, and the crystal optical axis 351 of the second birefringent crystal 35 is arranged to be located in the plane formed by the propagation direction 301 and the second direction 303, that is, the crystal optical axis 351 of the second birefringent crystal 35 is preferably perpendicular to the first direction 302. Thus, the image imaging quality is better.
Still further, the crystal optic axis 331 of the first birefringent crystal 33 is perpendicular to the second direction 303 and forms an angle of 45 ° with the first direction 301, and the crystal optic axis 351 of the second birefringent crystal 35 is preferably perpendicular to the first direction 302 and forms an angle of 45 ° with the second direction 303. Thus, the image forming quality is optimal.
Further, the optical axis 361 of the first phase retarder 36 is perpendicular to the propagation direction 301 of the light, and forms an angle of 45 degrees with both the first direction 302 and the second direction 303, thereby completing the position-limiting retardation function.
The invention realizes a multi-depth-of-field spherical imaging image output mode by utilizing the first birefringent crystal 33, the second birefringent crystal 35 and the first phase retarder 36 arranged between the first birefringent crystal 33 and the second birefringent crystal 35, and can ensure that the quality of image output is maintained in a high-quality output mode of a spherical surface, the image distortion is less and the imaging definition is improved.
Considering that the crystal optical axis 331 of the first birefringent crystal 33 can be perpendicular to the second direction 303, and the crystal optical axis 351 of the second birefringent crystal 35 can be perpendicular to the first direction, but since the crystal optical axis 331 of the first birefringent crystal 33 is not parallel to the first direction 302, and the crystal optical axis 351 of the second birefringent crystal 35 is not parallel to the second direction 303, the positions of images formed by the first birefringent crystal 33 and the second birefringent crystal 35 and observed at a fixed point cannot be consistent, and the images in two depths of field are misaligned.
Referring to fig. 10 to 11, fig. 10 is a schematic diagram of optical paths of the first birefringent crystal 33 and the third birefringent crystal 37 shown in fig. 1, and fig. 11 is a schematic diagram of optical paths of the second birefringent crystal 35 and the fourth birefringent crystal 38 shown in fig. 1.
In one embodiment of the present invention, in order to overcome the problem of misalignment of the images over two depths of field, the refractive element 30 in one embodiment of the present invention is further provided with a third birefringent crystal 37 and a fourth birefringent crystal 38. The third birefringent crystal 37 is located between the first birefringent crystal 33 and the first phase retarder 36, and the fourth birefringent crystal 38 is located between the second birefringent crystal 35 and the projection unit 34.
In order to eliminate the image misalignment, the crystal optic axis 331 of the first birefringent crystal 33 and the crystal optic axis 371 of the third birefringent crystal 37 are both set perpendicular to the second direction 303, and the crystal optic axis 331 of the first birefringent crystal 33 and the first direction 302 form θ1At an angle, the crystal optic axis 371 of the third birefringent crystal 37 forms- θ with the first direction 3021An angle;
the crystal optic axis 351 of the second birefringent crystal 35 and the crystal optic axis 381 of the fourth birefringent crystal 38 are arranged to be perpendicular to the first direction 302, and the crystal optic axis 351 of the second birefringent crystal 35 and the second direction 303 form θ2At an angle, the fourth birefringent crystal 38 forms- θ with the second direction 3032And (4) an angle. At the moment, the images on the two depths of field can keep consistent after being superposed due to the symmetrically distributed position relation, thereby eliminating image dislocation and improving the definition of the images.
Further, θ will be1The angle is set to 45 degrees, at this time, the image symmetry of the first birefringent crystal 33 and the third birefringent crystal 37 during refraction is optimal, and the dislocation eliminating effect of the image is optimal; and/or the presence of a catalyst in the reaction mixture,
will theta2The angle is set to 45 °, and the image symmetry of the second birefringent crystal 35 and the fourth birefringent crystal 38 is optimal when they are refracted, and the misalignment cancellation effect of the image is optimal.
According to the invention, the images on different birefringent crystal units are symmetrically distributed by adjusting the optical axis positions of the first birefringent crystal 33, the second birefringent crystal 35, the third birefringent crystal 37 and the fourth birefringent crystal 38, so that the superposed images can be kept consistent, thereby eliminating image dislocation and improving the definition of the images.
Referring to fig. 12, fig. 12 is a schematic structural diagram of an augmented reality display assembly 100 according to another embodiment of the invention.
In one embodiment of the present invention, in order to compensate for the loss of light intensity and display brightness in consideration of the insufficient light intensity when linearly polarized light is imaged, the augmented reality display assembly 100 in this embodiment additionally provides an optical switch on the basis of the first optical switch 32, and two optical switches having the same switching state and one polarization reflector are used to compensate for the loss of light intensity.
Specifically, the augmented reality display assembly 100 further includes a second optical switch 39, the second optical switch 39 being located between the projection unit 34 and the fourth birefringent crystal 38; the second optical switch 39 and the first optical switch 32 are in the same operating state, that is, the second optical switch 39 and the first optical switch 32 are in the on or off state at the same time, and the operating states of the two are in the same coupling state under the control of the control unit.
As far as the structure of the second optical switch 39 itself is concerned, it may adopt a conventional structure, either using the same switching device as the first optical switch 32 or using a different switching device from the first optical switch 32. In the present embodiment, in consideration of the compatibility of the entire components, the second optical switch 39 and the first optical switch 32 both use liquid crystal light valves; preferably, the response time of the second optical switch 39 is set to 10 milliseconds or less, and the light transmittance of the second optical switch 39 is set to a range of more than 90%.
It is understood that in other embodiments, the second optical switch 39 may also be an electro-optical switch, a thermo-optical switch, an acousto-optical switch, a micro-mechanical optical switch, a conventional mechanical optical switch, or other types of optical switch elements, as long as the type of optical switch elements can achieve polarization direction adjustment; the response time and the transmittance of the second optical switch 39 can be selected according to actual working conditions, for example, the response time of the second optical switch 39 is set to be more than 10 milliseconds, and the transmittance of the second optical switch 39 is set to be less than 90%.
The eyepiece unit 20 in the augmented reality display assembly 100 further includes a second phase retarder 22 and an optical coupler 23, the mirror 21 in the eyepiece unit 20 employs a polarizing reflector, and the second phase retarder 22 is located between the polarizing reflector and the optical coupler 23. The second phase retarder 22 has a phase retardation of pi/4, which is used to retard the phase of linearly polarized light; the optical coupler 23 is used to reflect linearly polarized light, and the polarizing reflector is used to selectively reflect or transmit polarized light, which is capable of allowing polarized light perpendicular to the original polarization direction to transmit, and reflecting polarized light of the other polarization direction.
The display principle of the higher brightness of the lower augmented reality display assembly 100 is explained as follows:
the first optical switch 32 and the second optical switch 39 are in the same working state, when the first optical switch 32 and the second optical switch 39 are both in the closed state, the linearly polarized light polarized by the first polarizer 31 cannot be changed in polarization direction by the first optical switch 32 and the second optical switch 39, and is reflected when being projected onto the polarization reflector, so that the linearly polarized light passes through the second phase retarder 22 and realizes the phase delay of pi/4; the linearly polarized light is reflected by the optical coupler 23 after achieving the phase delay of pi/4, passes through the second phase retarder 22 again and achieves the phase delay of pi/4 again; linearly polarized light realizes pi/2 phase delay after being subjected to pi/4 phase delay superposition twice, and at the moment, the linearly polarized light is converted into linearly polarized light vertical to the original vibration direction, so that the linearly polarized light transmits through the polarization reflector and forms an image in human eyes;
when the first optical switch 32 and the second optical switch 39 are both in an on state, the linearly polarized light polarized by the first polarizer 31 returns to the polarization direction of itself after passing through the first optical switch 32 and the second optical switch 39 for polarization conversion twice, and is reflected when being projected onto the polarization reflector, thereby passing through the second phase retarder 22 and realizing the phase retardation of pi/4; the linearly polarized light is reflected by the optical coupler 23 after achieving the phase delay of pi/4, passes through the second phase retarder 22 again and achieves the phase delay of pi/4 again; the linearly polarized light realizes the phase delay of pi/2 after being subjected to the phase delay superposition of pi/4 twice, and the linearly polarized light is converted into the linearly polarized light vertical to the original vibration direction at the moment, so that the linearly polarized light transmits through the polarization reflector and is imaged in human eyes.
The augmented reality display assembly 100 provided by the invention utilizes the second phase retarder 22 and the optical coupler 23 to convert the polarized light type for imaging, improves the image display brightness, can improve the image display brightness to the level of 4 times of the traditional image display brightness in theory, and has higher application value and wide application prospect.
Further, considering that the optical rotation capabilities of the first optical switch 32 and the second optical switch 39 are limited, the first optical switch 32 and the second optical switch 39 do not have enough capabilities to completely convert the linearly polarized light into the initial state after twice conversion, so that the optical signal output by the second optical switch 39 has two linearly polarized lights with different polarization directions at the same time, which may cause the contrast of the image display to be reduced; for this reason, the augmented reality display module 100 in the present embodiment further includes a second polarizer 391 in the refraction unit 30, and the second polarizer 391 is located between the second optical switch 39 and the projection unit 34.
The second polarizer 391 plays a role of polarizing again, so that the second optical switch 39 is filtered for the linearly polarized light with the redundant polarization direction capable of being completely converted, and only the linearly polarized light with the same polarization direction as the initial polarization direction is left, thereby ensuring the contrast of image display.
Further, the first polarizer 31 employs a polarizing plate; and/or the presence of a catalyst in the reaction mixture,
the second polarizer 391 also employs a polarizing plate.
The polarizing ability of the polarizing film is stable, so that the polarizing function of the whole assembly is facilitated to be realized, and the polarizing film has great advantage in cost performance.
It is understood that in other embodiments, the phase delay of the second retarder 22 may be different from pi/4, as long as the sum of the accumulated phase delays of the front and back of the second retarder 22 is pi/2.
The present invention further provides an augmented reality display device (not shown) including a wearable device body (not shown) and an augmented reality display assembly 100 disposed on the device body. The augmented reality display device provided by the invention enables the imaging modes of the device when the device is used for realizing image display in multiple depths of field to be consistent by using the augmented reality display component 100, and can keep the imaging modes of the spherical mirror with high quality
According to the invention, by adjusting the optical axis positions of the first birefringent crystal 33, the second birefringent crystal 35, the third birefringent crystal 37 and the fourth birefringent crystal 38, images on different birefringent crystal units are symmetrically distributed, so that the superposed images can be kept consistent, further image dislocation is eliminated, the image definition is improved, and the method has a wide application prospect and a high economic value.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that suitable changes and modifications of the above embodiments are within the scope of the claimed invention as long as they are within the spirit and scope of the present invention.
Claims (10)
1. An augmented reality display assembly comprises an image unit, an ocular unit and a refraction unit arranged between the image unit and the ocular unit, wherein the refraction unit comprises a first optical switch, a first birefringent crystal, a first phase retarder and a second birefringent crystal, the first optical switch is arranged between the image unit and the first birefringent crystal, the phase delay of the first phase retarder is pi/2 and is arranged between the first birefringent crystal and the second birefringent crystal;
the refraction unit is characterized by further comprising a first polarizer, a third birefringent crystal and a fourth birefringent crystal, wherein the first polarizer is arranged between the image unit and the first optical switch, the third birefringent crystal is arranged between the first birefringent crystal and the first phase retarder, and the fourth birefringent crystal is arranged between the second birefringent crystal and the eyepiece unit;
naming the polarization direction of linearly polarized light output by the first polarizer as a first direction, naming the direction perpendicular to the first direction as a second direction, wherein the crystal optical axis of the first birefringent crystal and the crystal optical axis of the third birefringent crystal are both perpendicular to the second direction, and the crystal optical axis of the first birefringent crystal forms theta relative to the first direction1An angle, a crystal optic axis of the third birefringent crystal forming-theta with respect to the first direction1An angle;
the crystal optical axis of the second birefringent crystal and the crystal optical axis of the fourth birefringent crystal are both perpendicular to the first direction, and the crystal optical axis of the second birefringent crystal forms theta relative to the second direction2An angle, a crystal optic axis of the fourth birefringent crystal forming- θ with respect to the second direction2And (4) an angle.
2. As claimed in claimThe augmented reality display assembly of claim 1, wherein θ is1Is 45 degrees; and/or the presence of a catalyst in the reaction mixture,
theta is described2Is 45 degrees.
3. The augmented reality display assembly of claim 2, wherein the refraction unit further comprises a second optical switch, the image unit comprising a polarizing reflector, a second phase retarder disposed between the fourth birefringent crystal and the polarizing reflector, and an optical coupler, the second phase retarder disposed between the polarizing reflector and the optical coupler and retarding a phase of polarized light transmitted between the polarizing reflector and the optical coupler.
4. The augmented reality display assembly of claim 3, wherein the phase retarder has a phase retardation of pi/4.
5. The augmented reality display assembly of claim 4, wherein the refraction unit further comprises a second polarizer disposed between the second optical switch and a polarizing reflector.
6. The augmented reality display assembly of claim 5, wherein the first polarizer is a polarizer; and/or the presence of a catalyst in the reaction mixture,
the second polarizer is a polarizing plate.
7. The augmented reality display assembly of claim 1, wherein the brightness of the image cell is 5000 nits or more; and/or the presence of a catalyst in the reaction mixture,
the refresh rate of the picture cells is above 120 Hz.
8. The augmented reality display assembly of claim 1, wherein the response time of the light switch is less than 10 milliseconds; and/or the presence of a catalyst in the reaction mixture,
the light transmittance of the optical switch is greater than 90%.
9. The augmented reality display assembly of claim 1, wherein the resolution of the image unit is 1080P or greater.
10. An augmented reality display device comprising an augmented reality display assembly, wherein the augmented reality display assembly is the augmented reality display assembly of any one of claims 1 to 9.
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| CN112596245A (en) * | 2020-12-28 | 2021-04-02 | 歌尔股份有限公司 | Optical assembly and AR equipment |
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