CN115981003A - Optical module and wearable equipment - Google Patents
Optical module and wearable equipment Download PDFInfo
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- CN115981003A CN115981003A CN202211710211.5A CN202211710211A CN115981003A CN 115981003 A CN115981003 A CN 115981003A CN 202211710211 A CN202211710211 A CN 202211710211A CN 115981003 A CN115981003 A CN 115981003A
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Abstract
The embodiment of the application provides an optical module and wearable equipment; the optical module comprises an imaging lens group, and a light splitting element, a phase retarder and a polarization reflecting element which are arranged in the imaging lens group; wherein the phase retarder is located between the light splitting element and the polarization reflecting element; the optical module further comprises a display screen, the display screen is arranged on one side of the imaging lens group and is located on the same optical axis with the imaging lens group, and the display screen is configured to be capable of moving along the optical axis direction relative to the imaging lens group so as to adjust the rear intercept of the optical module; the optical module satisfies: the absolute distance | D (x) | that the display screen moves along the direction of the optical axis is proportional to the spatial position x of the eye box. The optical module provided by the embodiment of the application can realize high-definition imaging in the full-eye box range under a large field angle.
Description
Technical Field
The embodiment of the application relates to the technical field of optical imaging, and more specifically, the embodiment of the application relates to an optical module and wearable equipment.
Background
Virtual reality equipment is based on the imaging characteristic that optical module can enlarge image display in the short distance, realizes virtual reality equipment user's immersive visual experience. Different users will influence the actual display effect of the optical module due to the difference of head circumference and pupil distance.
In the design of the existing virtual reality optical scheme, in order to ensure that the imaging quality of the edge of the eye box meets the design requirements, the imaging quality of the center of the eye box and the edge of the eye box can be balanced, namely the MTF of the center of the eye box is properly reduced, so that the MTF of the edge of the eye box is improved, and meanwhile, the curve of the MTF of the whole eye box relative to the field of view inevitably has the phenomenon of fluctuation, which comes from the defocusing phenomenon caused in order to take account of the MTF of the edge eye box. Present virtual reality equipment design is fixed screen design, can have out of focus phenomenon when considering that different eye box positions homoenergetic well formation of image, restricts the promotion of formation of image quality.
Disclosure of Invention
The utility model aims at providing a new technical scheme of optical module and wearable equipment can realize full eye box within range high definition formation of image under the big angle of vision.
In a first aspect, the present application provides an optical module. The optical module comprises an imaging lens group, and a light splitting element, a phase retarder and a polarization reflecting element which are arranged in the imaging lens group; wherein the phase retarder is located between the light splitting element and the polarization reflecting element;
the optical module further comprises a display screen, the display screen is arranged on one side of the imaging lens group and is located on the same optical axis with the imaging lens group, and the display screen is configured to be capable of moving along the optical axis direction relative to the imaging lens group so as to adjust the rear intercept of the optical module;
the optical module satisfies: the absolute distance | D (x) | that the display screen moves along the direction of the optical axis is proportional to the spatial position x of the eye box.
Optionally, a moving distance D (x) of the display screen in the optical axis direction and the spatial position x of the eyebox satisfy a downward opening parabolic relationship: x is the number of 2 ＝-2*p*(D(x)-d)；
Wherein x belongs to R, D (x) is less than or equal to D, D is the distance from the display screen corresponding to the center position of the eye box to the imaging lens group, D is greater than 0,p is the distance from the focus of the parabola to the parabola quasi-line, p is greater than 0, the coordinate of the focus is (0,d-p/2), and the quasi-line equation is y = p/2+d.
Optionally, a moving distance D (x) of the display screen in the optical axis direction and the spatial position x of the eyebox satisfy the following function equation:
D(x)＝p1*x 6 +p2*x 5 +p3*x 4 +p4*x 3 +p5*x 2 +p6*x+p7；
wherein-1.3 e -07 ＜p1＜-1.0e -05 ，-1.2e -06 ＜p2＜-1.0e -04 ，-1.1e -05 ＜p3＜-1.0e -03 ，-1.3e -05 ＜p4＜-1.0e -02 ，-1.2e -05 ＜p5＜-1.0e -02 ，-1.1e -05 ＜p6＜-1.0，1.5＜p7＜50；
The x represents the radial distance from any position of the eye box to the center of the eye box, x =0 represents the center position of the eye box, x <0 represents the spatial position of the eye box along the negative direction by taking the center of the eye box as a datum point, x >0 represents the spatial position of the eye box along the positive direction by taking the center of the eye box as a datum point, and p7 is the distance from the side, close to the display screen, of the imaging lens group to the display screen.
Optionally, a function equation satisfied by a moving distance D (x) of the display screen along the optical axis and a spatial position x of the eyebox satisfies for the imaging lens group formed by any surface type lens, that is: data fitting R 2 ≥0.95。
Optionally, the optical module further includes an eye tracking assembly disposed near the imaging lens group;
the eyeball tracking assembly is used for acquiring eyeball position information of a wearer and controlling and adjusting the distance between the display screen and the imaging lens group.
Optionally, the display screen is used for emitting circularly polarized light to the imaging mirror group, one side of the display screen close to the imaging mirror group is a light emitting side, and the light emitting side is provided with a screen protection device.
Optionally, the imaging lens group comprises at least one lens, and the surface type of the lens comprises a plane, a spherical surface, an aspheric surface, a fresnel surface or a free-form surface.
Optionally, the imaging lens group includes a first lens and a second lens, and the second lens is located between the first lens and the display screen;
the light splitting element is arranged on any side of the second lens, and the phase retarder and the polarization reflecting element are arranged on any side of the first lens.
Optionally, the light splitting element is disposed on a surface of the second lens close to the display screen;
the optical module further comprises a polarizing element, the phase retarder, the polarization reflecting element and the polarizing element are sequentially stacked to form an overlapped element, and the overlapped element is arranged on the surface, away from the display screen, of the first lens.
Optionally, the fast axis direction of the light splitting element forms a 45-degree angle with the transmission direction of the polarization reflection element.
Optionally, the polarization direction of the polarization element is the same as the polarization transmission direction of the polarization reflective element.
Optionally, the optical module satisfies: the total system length TL of the optical module and the caliber D of the largest lens in the imaging module max Ratio of (0.4) < TL/D max ＜0.9。
Optionally, the effective focal length EFFL of the optical module is: 13mm < EFFL < 33mm.
In a second aspect, the present application provides a wearable device. The wearable device includes:
a housing; and
the optical module according to the first aspect, wherein the optical module is provided in the housing.
The beneficial effect of this application lies in:
according to the embodiment of the application, the optical module is provided, through designing the display screen with the adjustable rear intercept, the design freedom degree can be increased for the optical module, the distance between the display screen and the imaging lens group in the optical module is reasonably adjusted, the optical imaging quality at different eye box positions has the back focus compensation effect, the design of the optical module under a large-field-angle full-eye box is facilitated, the imaging quality can be further improved, and the full-eye box within-range high-definition imaging under the large-field-angle can be realized.
Other features of the present description and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and together with the description, serve to explain the principles of the specification.
Fig. 1 is a schematic structural diagram of an optical module according to an embodiment of the present disclosure;
FIG. 2 is a graph showing the variation of MTF with the field of view at different positions of an eye box of an optical module;
FIG. 3 is an out-of-focus view of an edge cell of the optics module;
FIG. 4 is a schematic view of central field of view on-axis/off-axis object point chief rays;
FIG. 5 is a schematic structural diagram of an optical module corresponding to the center position of an eye box in embodiment 1 of the present application (back intercept: 2.833 mm);
FIG. 6 is a schematic structural diagram of an optical module corresponding to an 8mm position of an edge of an eye box in embodiment 1 of the present application (back intercept: 2.497 mm);
FIG. 7 shows MTF values at the center of the eye box in example 1 of the present application;
FIG. 8 shows MTF values of 8mm at the edge of the eye box in example 1 of the present application;
FIG. 9 is a defocus curve at the center of the eye box in example 1 of the present application;
FIG. 10 is the defocus curve of the eye box edge in example 1 of the present application;
FIG. 11 is a schematic view of an optical module corresponding to the center of the eye box in embodiment 2 of the present application (back intercept: 3.358 mm);
FIG. 12 is a schematic view of an optical module corresponding to the 7mm position of the edge of the eye box in embodiment 2 of the present application (back intercept: 3.314 mm);
FIG. 13 shows MTF values at the center of the eye box in example 2 of the present application;
FIG. 14 shows MTF values at 7mm of the edge of the eye box in example 2 of the present application;
FIG. 15 is a defocus curve at the center of the eye box in example 2 of the present application;
fig. 16 is a diagram showing the edge defocus curve of the eye box in example 2 of the present application.
Description of reference numerals:
1. a first lens; 2. a second lens; 3. a display screen; 4. a screen saver device; 5. a light-splitting element; 6. a phase retarder; 7. a polarizing reflective element; 8. a polarizing element; 9. an eye tracking assembly; 10. a laminating element; 01. the human eye.
Detailed Description
Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses.
Techniques and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be considered a part of the specification where appropriate.
In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
According to an aspect of embodiments of the present application, there is provided an optical module suitable for being applied to a Head Mounted Display (HMD), such as a VR HMD or an AR HMD. The VR head-mounted display device may include, for example, VR glasses or a VR helmet, and the AR head-mounted display device may include, for example, AR glasses and an AR helmet of a free-form prism scheme or a Birdbath scheme, which is not particularly limited in this embodiment of the present application.
With reference to fig. 1, the optical module provided in the embodiment of the present application includes an imaging lens group, and a beam splitting element 5, a phase retarder 6, and a polarization reflecting element 7, which are disposed in the imaging lens group; wherein the phase retarder 6 is located between the light splitting element 5 and the polarization reflecting element 7;
the optical module further comprises a display screen 3, the display screen 3 is arranged on one side of the imaging lens group and is located on the same optical axis with the imaging lens group, and the display screen 3 is configured to be capable of moving along the optical axis direction relative to the imaging lens group so as to adjust the rear intercept of the optical module;
the optical module satisfies:
the absolute distance | D (x) | that the display screen 3 moves in the direction of the optical axis is proportional to the spatial position x of the eyebox.
In the above embodiment of the present application, through adjusting the position of the display screen 3, the defocus correction in the full eye box range is realized, and the imaging quality of the optimal performance under the corresponding optical structure is obtained under the full field of view of the full eye box. That is to say, the optical scheme provided by the embodiment of the present application realizes the effect of defocus correction by fixing the lenses in the imaging lens group and moving the display screen 3.
In the optical scheme provided by the embodiment of the present application, a manner of fixing the display screen 3 and moving the lens is not adopted, and mainly the distance between the human eye 01 and the front end of the imaging lens group, that is, the eye distance, needs to be strictly controlled in order to move the lens. Thus, two or more lenses must be installed in the optical module, one of the lenses needs to be fixed at the end of the imaging lens group close to the human eye 01 to ensure that the maximum field angle is unchanged, and the other lens is designed to be movable. However, the number of the lenses is limited, and the flexibility of the design of the optical module is reduced.
In the design of the existing virtual reality optical scheme, in order to ensure that the imaging quality of the edge of the eye box meets the design requirement, the imaging quality of the center of the eye box and the edge of the eye box can be balanced, that is, the MTF of the center of the eye box is properly reduced, so that the MTF of the edge of the eye box is improved, and meanwhile, the curve of the MTF of the whole eye box relative to the field of view inevitably has the phenomenon of fluctuation, that is, the first derivative of the MTF numerical curve from the center field of view to the edge field of view is different in number, as shown in fig. 2, the problem comes from the defocusing phenomenon caused in order to consider the MTF of the edge of the eye box, as shown in fig. 3. Specifically, defocus means that the image plane is not on the ideal image plane, and the amount of defocus is the distance between the ideal image plane and the actual image plane. In the design of the virtual reality optical scheme, a reverse design mode is usually adopted, that is, an image plane is a light emitting plane (capable of emitting imaging light) of the display screen 3, so that the image quality influence caused by the defocusing of the optical module can be eliminated by adjusting the distance between the light emitting plane of the display screen 3 and the imaging lens group.
From the analysis of geometrical optics, it can be seen that when the optical axis of the eyeball deviates from the designed optical axis of the optical module, the optical path difference of the chief ray of the on-axis/off-axis object point passing through the optical device is reduced. To obtain good imaging quality, i.e. total optical path difference Δ General assembly If =0, the optical path difference of the principal ray of the on-axis/off-axis object point outside the optical element is required to be increased, and it can be derived based on the model shown in fig. 4 that: optical path difference of chief ray of object point on/off axis of central visual field axis delta = L Outside of shaft -L On the shaft If the functional relation Δ = d × tan (θ/2) exists, d is the entrance pupil aperture of the optical module on the side close to the display screen, then an increase in the optical path difference requires a decrease in the distance (air gap) between the imaging mirror assembly and the display screen 3. That is, as the center of the eye box is farther from the display screen 3, the display screen 3 should approach the imaging lens group. Therefore, good imaging quality can be obtained under the condition of considering different eye box positions, and the condition that the imaging quality is restricted by the defocusing phenomenon is avoided.
As known from the conservation of the etendue, the aperture angle is inversely proportional to the cross-sectional area under the same optical module, so under a large eyebox and a large field angle, the aberration correction capability of the optical module is required to be higher to improve the resolution of the optical module, which requires that the optical module must have a stricter processing tolerance, the production yield is also affected, and the requirement on the optical design is very high.
In the optical module provided in the embodiment of the present application, in order to correct defocus in the whole eye box, the absolute distance that the display screen 3 moves in the optical axis direction is designed to be proportional to the spatial position of the eye box, and according to the optical path difference Δ = d × tan (θ/2), the increase of the optical path difference requires the distance (air gap) between the imaging mirror group and the display screen to be reduced, that is, the display screen position corresponding to the center eye box position is the maximum distance position from the display screen 3 in the whole eye box to the imaging mirror group.
The optical module that this application embodiment provided, through the display screen 3 of intercept adjustable behind the design, can increase the design degree of freedom for optical module, through the distance between display screen 3 and the formation of image mirror group among the reasonable adjustment optical module, optical imaging quality to different eyebox positions department has back focus compensation effect, be favorable to the optical module design under the full eyebox of big angle of vision, can further promote the formation of image quality, can realize full eyebox within range high definition formation of image under the big angle of vision.
In the optical scheme provided by the embodiment of the application, a solution to the problem that defocusing exists at different eye box positions is innovatively provided at the design end of the optical module, and the designed optical module has the performance advantages of large eye box, large field angle and high resolution.
In some examples of the present application, a moving distance D (x) of the display screen 3 in the optical axis direction and a spatial position x of the eyebox satisfy a parabolic relationship with an opening facing downward: x is the number of 2 = -2*p (D (x) -D); wherein x belongs to R, D (x) is less than or equal to D, D is the distance from the display screen corresponding to the center position of the eye box to the imaging lens group, and D is the distance from the display screen to the imaging lens group>0,p is the distance from the focus of the parabola to the parabola directrix, p>0, the coordinates of the focal spot are (0,d-p/2), and the quasi-line equation is y = p/2+d.
That is, in the optical scheme of the present application, the spatial position x of the eye box should be considered when the display screen 3 is moved.
Specifically, the moving distance D (x) of the display screen 3 in the optical axis direction and the spatial position x of the eye box satisfy a parabolic relationship with the opening facing downward. Thus, whether the display screen 3 moves upwards or downwards, the closer the display screen 3 is to the imaging lens group when the centre of the eye box is farther from the display screen 3. Therefore, the influence of defocusing can be eliminated, and the formed optical module has the performance advantages of large eye box, large field angle and high resolution.
Further, the moving distance D (x) of the display screen along the optical axis direction and the spatial position x of the eyebox satisfy the following function equation:
D(x)＝p1*x 6 +p2*x 5 +p3*x 4 +p4*x 3 +p5*x 2 +p6*x+p7；
wherein-1.3 e -07 ＜p1＜-1.0e -05 ，-1.2e -06 ＜p2＜-1.0e -04 ，-1.1e -05 ＜p3＜-1.0e -03 ，-1.3e -05 ＜p4＜-1.0e -02 ，-1.2e -05 ＜p5＜-1.0e -02 ，-1.1e -05 < p6 < -1.0,1.5 < p7 < 50; x represents the radial distance from any position of the eye box to the center of the eye box, x =0 represents the center position of the eye box, and x represents<0 represents the spatial position of the eye box in the negative direction with the center of the eye box as a reference point, x>And 0 represents the spatial position of the eye box along the positive direction by taking the center of the eye box as a datum point, and p7 is the distance from the side, close to the display screen, of the imaging mirror group to the display screen.
On the basis that the moving distance D (x) of the display screen 3 along the optical axis direction and the spatial position x of the eye box meet the parabolic relation with the downward opening, the function equation is fitted through multiple times of light rays, and therefore the moving rule of the display screen 3 is further limited.
Where x represents the radial distance of any location of the eye box from the center of the eye box.
It should be noted that the moving distance D (x) of the display screen 3 along the optical axis direction and the spatial position x of the eyebox satisfy a parabolic relationship with a downward opening, and the moving distance D (x) of the display screen along the optical axis direction and the spatial position x of the eyebox satisfy the following function equation, which are both suitable for rotationally symmetric or non-rotationally symmetric optical design architectures.
In the optical module that this application embodiment provided, control 3 modes of moving the rule of display screen are diversified, can select in a flexible way as required.
Wherein, the function equation satisfied by the moving distance D (x) of the display screen 3 along the optical axis direction and the space position x of the eye box is applied to any surface type lens shapeThe imaging lens group meets the following requirements: data fitting R 2 ≥0.95。
According to the above-mentioned function equation fitting the moving distance D (x) of the display screen 3 in the optical axis direction to the spatial position x of the eye box, where R is 2 Is a parameter for characterizing the degree of fitting, and the fitting parameter in the present application can be up to 0.95 or even higher.
It should be noted that any optical design can be fitted in the above range by using the above function equation, and the fitting accuracy can reach more than 0.95, and this design is considered to be within the protection scope of the present application.
In some examples of the present application, referring to fig. 1, the optical module further comprises an eye tracking assembly 9, the eye tracking assembly 9 being disposed adjacent to the imaging lens group; the eyeball tracking assembly 9 is used for acquiring eyeball position information of a wearer, and is used for controlling and adjusting the distance between the display screen 3 and the imaging lens group.
In order to realize the design of the virtual reality optical module for high-definition imaging in the range of the whole eye box under a large field angle, the optical scheme of the embodiment of the application also provides a large eye box virtual reality optical design scheme based on eyeball tracking.
Specifically, the optical module according to the embodiment of the present application can capture eyeball position information of a user through the eyeball tracking component 9, and then adjust the spatial position of the display screen 3 in the optical module through the processor according to the obtained eyeball position information, so that high-definition imaging in a large eyebox range can be realized in VR product design.
Optionally, the eye tracking assembly 9 may include an infrared light source and an infrared camera opposite the human eye 01.
Furthermore, the eye tracking assembly 9 should be placed as close as possible to the human eye 01 to improve the accuracy of eye tracking.
In some examples of the present application, referring to fig. 1, the display screen 3 is configured to emit circularly polarized light to the imaging lens group, and one side of the display screen 3 close to the imaging lens group is a light exit side, and the light exit side is provided with a screen protection device 4.
The display screen 3 is, for example, a micro display screen. The display screen 3 can be controlled by a driving device (e.g. a motor) to move linearly along the optical axis direction to approach or depart from the imaging lens group.
Optionally, the display screen 3 may be any screen that can make the light emitting surface into a rotation symmetric structure, such as a microeoled screen or an LCD screen.
The screen protection device 4 is, for example, a glass protection plate, which can be adhesively fixed on the light emitting surface of the display screen 3 to protect the display screen 3.
It should be noted that, referring to fig. 1, the light emitted by the display screen 3 should be circularly polarized light, which can directly enter the left imaging lens group, and the clear picture can be displayed in the human eye 01 after the post-processing by the imaging lens group.
When the display screen 3 emits linearly polarized light, the imaging light can be converted from the linearly polarized light to circularly polarized light by the phase retarder, the polarization reflecting element and the like, and then the circularly polarized light enters the imaging lens group.
Optionally, the imaging lens group includes at least one lens, and the surface type of the lens includes a plane, a spherical surface, an aspherical surface, a fresnel surface, or a free-form surface.
In the optical module provided in the embodiment of the present application, the number of the lenses may be set to be one, two, or more than or equal to three. The large number of lenses is advantageous for improving the imaging quality, but increases the weight, volume and production cost of the optical module. In general, 1 to 3 optical lenses are generally used in VR devices based on the application of a folded optical path.
The surface of the lens can be other surface types such as a plane, a spherical surface, an aspheric surface, a fresnel surface, a free-form surface and the like. Specifically, the plane, the spherical surface, the aspheric surface and the Fresnel surface form a rotationally symmetric optical architecture, and the free-form surface correspondingly forms a non-rotationally symmetric optical architecture. The optical module that this application embodiment provided does not have the requirement to the face type of lens for optical module's design degree of freedom is higher.
In one example, referring to fig. 1, the imaging lens group includes a first lens 1 and a second lens 2, and the second lens 2 is located between the first lens 1 and the display screen 3; the beam splitter 5 is provided on either side of the second lens 2, and the phase retarder 6 and the polarization reflection element 7 are provided on either side of the first lens 1.
Optionally, the light splitting element 5 is disposed on a surface of the second lens 2 close to the display screen 3; the optical module further comprises a polarization element 8, the phase retarder 6, the polarization reflection element 7 and the polarization element 8 are sequentially stacked to form an overlapping element 10, and the overlapping element 10 is arranged on the surface, far away from the display screen 3, of the first lens 1.
In the optical module according to the embodiment of the present application, the number of the lenses includes, but is not limited to, the two lenses, and the number of the lenses can also be flexibly adjusted according to specific needs. With the increase of the number of the lenses, although the imaging quality of the optical module can be improved, the size of the optical module along the optical axis direction (transverse direction) is also affected, resulting in a larger volume and increased weight of the optical module.
The light splitting element 5 is, for example, a half-mirror device, and can transmit a part of light and reflect another part of light.
Optionally, the reflectivity of the light splitting element is 47% to 53%, for example.
The phase retarder 6 is, for example, a quarter-wave plate. Of course, the phase retarder 6 can be set as other phase retarders such as half-wave plate, etc. according to the requirement.
The phase retarder 6 may be used to change the polarization state of the light. For example, for converting linearly polarized light into circularly polarized light, or for converting circularly polarized light into linearly polarized light.
The polarization reflection element 7 is a polarization reflector for horizontally linearly polarized light reflection and vertically linearly polarized light transmission, or a polarization reflector for reflecting linearly polarized light with any specific angle and transmitting linearly polarized light in the direction perpendicular to the angle. In the embodiment of the present application, the phase retarder 6 and the polarization reflective element 7 are both used to resolve and transmit light.
The polarization element 8 is provided to reduce stray light caused by the polarized reflectance of the polarization reflector being not 100%.
The arrangement positions of the beam splitter 5, the phase retarder 6 and the polarization reflective element 7 in the lens group are flexible, and the beam splitter, the phase retarder 6 and the polarization reflective element 7 can be arranged between the first lens 1 and the second lens 2 as needed, for example, but it is required to ensure that the phase retarder 6 is arranged between the beam splitter 5 and the polarization reflective element 7.
Wherein, the fast axis direction of the light splitting element 5 and the transmission direction of the polarized reflection element 7 form an included angle of 45 degrees.
Wherein the polarization direction of the polarization element 8 is the same as the polarization transmission direction of the polarization reflection element 7.
In the example of this application, through adjusting the out-of-focus design structure of the different eye box position departments of position compensation of display screen 3 can be applied to virtual reality folding light path (pancake) optical module. The design of folding light path can reduce optical module's the total optical length, does benefit to the size that reduces optical module.
Of course, the optical scheme of the embodiment of the present application may also be used for a virtual reality fresnel optical module and other application types of optical modules with a large eye box and a large field angle, which is not limited to this.
Wherein the optical module satisfies: the total system length TL of the optical module and the caliber D of the largest lens in the imaging module max Ratio of (TL/D) 0.4 max ＜0.9。
Wherein the effective focal length EFFL of the optical module is as follows: 13mm < EFFL < 33mm.
The optical module provided by the embodiment of the application has the advantages of small integral volume and light weight, and can clearly image under a large-view-field full-eye box.
It should be noted that the field angle of the optical module can reach 110 degrees or more. Under the large field range, the image can be clearly formed in the full-eye box range.
Referring to fig. 1, a schematic structural diagram of an optical module according to an embodiment of the present disclosure is shown. Specifically, the optical module mainly comprises a first lens 1, a second lens 2, a display screen 3, a screen protector 4, a beam splitter 5, a phase retarder 6, a polarization reflection element 7, a polarization element 8 and an eyeball tracking assembly 9, wherein the phase retarder 6, the polarization reflection element 7 and the polarization element 8 form a superposed element 10, the superposed element 10 is arranged on the surface of the first lens 1 far away from the display screen 3, the beam splitter 5 is arranged on the surface of the second lens 2 close to the display screen 3, the screen protector 4 is attached to the display screen 3, and when the optical module is used, the first lens 1 is close to human eyes 01; the display screen 3 is a miniature display screen, and the distance between the display screen and the second lens 2 can be dynamically adjusted in the direction of an optical axis;
in the laminated element 10, the phase retarder 6 may be an element capable of converting the phase of light, such as a quarter-wave plate, the polarization reflection element 7 may reflect linearly polarized light in the horizontal/vertical direction and transmit the linearly polarized light in the vertical/horizontal direction, the polarization direction of the polarization element 8 is the same as the polarization transmission direction of the polarization reflection element 7, and the polarization element 8 in the laminated element 10 is configured to reduce stray light caused by the fact that the polarization reflectivity of the polarization reflection sheet is not 100%; the eyeball tracking component 9 is used for detecting the space position information of the eyeballs of the wearer, and after the space position information is fed back to a calculation center, the distance between the display screen 3 and the screen protection device 4 to the second lens 2 is adjusted to realize the clear imaging of different eyeboxes.
The process 9 adjustments are tracked to the eyeball behind the spatial position of display screen 3, and levogyration circular polarization light certainly display screen 3 launches, sees through in proper order screen protection device 4 beam splitting component 5 second lens 2 first lens 1 with in the coincide component 10 after the phase delay ware 6, turn into the linear polarization light line of level/vertical direction, process polarization direction is vertical/level in the coincide component 10 emergence reflection behind the polarization reflecting component 7 passes through once more turn into levogyration circular polarization light line behind the phase delay ware 6, pass through first lens 1 second lens 2 with turn into dextrorotation circular polarization light after the beam splitting component 6 reflection, pass through once more second lens 2 first lens 1 with after the coincide component 10, image in people's eye 01.
Among the optical module of above-mentioned example, can design the optical module of the big eye-box big angle of vision based on the frivolous optical scheme of two formula folding light path VR, wherein can track the position of the nimble display screen 3 of adjusting in the eyeball position of monitoring the wearer through the eyeball, effectively solved in virtual reality folding light path framework optical design, for taking into account under the big angle of vision the formation of image quality in the big eye-box and the different eye-box positions that cause have the design difficulty of out of focus, can promote the optical performance of full eye-box by a wide margin.
The optical module provided by the present application is described in detail by two embodiments below.
Example 1
Referring to fig. 5 and 6, the optical module includes a first lens 1, a second lens 2 and a display screen 3 sequentially disposed along a same optical axis, the first lens 1 and the second lens 2 are aspheric lenses, a surface 1R1 of the first lens 1 close to the eyes 01 is a plane, a surface 1R2 of the first lens 1 far away from the eyes 01 is a convex aspheric surface, a surface 2R1 of the second lens 2 close to the eyes 01 is a convex aspheric surface, and a surface 2R2 of the second lens 2 far away from the eyes 01 is also an aspheric convex surface;
the beam splitter 5 is provided on the surface 2R2 of the second lens 2, and the phase retarder 6, the polarization reflection element 7, and the polarization reflection element 8 form an overlapping element 10 and are provided on the surface 1R1 of the first lens 1; the fast axis direction of the light splitting element 5 and the transmission direction of the polarization reflecting element 7 form an included angle of 45 degrees; the polarization direction of the polarization element 8 is the same as the polarization transmission direction of the polarization reflection element 7;
the display screen 3 is configured to be movable along an optical axis relative to the second lens 2 to approach or depart from the second lens 2; the display screen 3 is a 2.5-inch screen, the screen is a fast LCD, the pixel size is 24.0 mu m, the luminous effective area is 43.2mm multiplied by 43.2mm, and the optical module view fieldThe angle is 110 degrees, and the optical module eye box is 4 +/-6 mm, and is 16mm in total; the optical module satisfies: the total system length TL of the optical module and the caliber D of the largest lens in the imaging module max Ratio of (0.5) < TL/D max Is less than 0.9; the effective focal length EFFL of the optical module is as follows: EFFL is more than 13.5mm and less than 26.5mm;
fig. 5 is a schematic structural diagram of an optical module corresponding to the center position of the eye box, and the rear intercept is 2.833mm; referring to fig. 6, a schematic diagram of an optical module structure corresponding to an 8mm position of an eye box edge is shown, wherein the rear intercept is 2.497mm;
the optical module further comprises an eyeball tracking assembly 9, wherein the eyeball tracking assembly 9 is used for acquiring eyeball position information of a wearer and controlling and adjusting the distance between the display screen 3 and the second lens 2.
Specific parameters of the optical module provided in example 1 are shown in table 1:
TABLE 1
Referring to fig. 7 and 8: fig. 7 shows MTF values at the center of the eye box, which can be seen to be relatively high, both greater than 0.8 or more; referring to fig. 8, MTF values at the edges of the eye boxes are shown, and the MTF values can also reach 0.5 or more, which indicates that the MTF curve of the optical module provided in embodiment 1 is better under the requirements of a large eye box and a large field angle, and the MTF values at the edges of the eye boxes do not have a bottoming condition.
Fig. 9 shows the defocus curve at the center of the eye box, fig. 9 corresponds to fig. 7 described above, and the vertical line in the middle of fig. 9 is the position of the display screen 3 where good imaging effect can be achieved by the display screen 3. Fig. 10 shows the defocus curve at the edge of the eye box, fig. 10 corresponds to fig. 8, the vertical line in the middle of fig. 10 is the position of the display screen, fig. 10 shows that the center position of the eye box is shifted, a good defocus effect is obtained by shifting the display screen 3 at the position of 8mm at the edge of the eye box, and it can be seen that the MTF value is decreased outside the vertical line in the middle.
Example 2
Referring to fig. 11 and 12, the optical module includes a first lens 1, a second lens 2 and a display screen 3 sequentially disposed along a same optical axis, where the first lens 1 and the second lens 2 are aspheric lenses, a surface 1R1 of the first lens 1 close to a human eye 01 is a concave aspheric surface, a surface 1R2 of the first lens 1 far away from the human eye 01 is a convex aspheric surface, a surface 2R1 of the second lens 2 close to the human eye 01 is a plane, and a surface 2R2 of the second lens 2 far away from the human eye 01 is also a convex aspheric surface;
the beam splitter 5 is provided on the surface 2R2 of the second lens 2, and the phase retarder 6, the polarization reflection element 7, and the polarization reflection element 8 form an overlapping element 10 and are provided on the surface 1R1 of the first lens 1; the fast axis direction of the light splitting element 5 and the transmission direction of the polarization reflecting element 7 form an included angle of 45 degrees; the polarization direction of the polarization element 8 is the same as the polarization transmission direction of the polarization reflection element 7;
the display screen 3 is configured to be movable along an optical axis relative to the second lens 2 to approach or depart from the second lens 2; the display screen 3 is a 2.5-inch screen, the screen is a fast LCD, the pixel size is 24.0 mu m, the luminous effective area is 43.2mm multiplied by 43.2mm, the field angle of the optical module is 110 degrees, and the optical module eye box is 4 +/-5 mm, and the total thickness is 14mm; the optical module satisfies: the total system length TL of the optical module and the caliber D of the largest lens in the imaging module max Ratio of (0.4) < TL/D max Less than 0.8; the effective focal length EFFL of the optical module is as follows: 24.5mm < EFFL < 32.5mm;
referring to fig. 5, a schematic diagram of an optical module structure corresponding to the center position of the eye box is shown, wherein the rear intercept is 3.358mm; referring to fig. 6, a schematic diagram of an optical module structure corresponding to an 8mm position of an eye box edge is shown, wherein the rear intercept is 3.314mm;
the optical module further comprises an eyeball tracking assembly 9, wherein the eyeball tracking assembly 9 is used for acquiring eyeball position information of a wearer and controlling and adjusting the distance between the display screen 3 and the second lens 2.
The specific parameters of the optical module provided in example 2 are shown in table 3:
TABLE 2
See fig. 13 and 14: fig. 14 shows MTF values at the center of the eye box, which can be seen to be relatively high, both greater than 0.8 or more; fig. 15 shows MTF values at the edges of the eyeboxes, which may also reach 0.4 or more, and this indicates that the MTF curve of the optical module provided in embodiment 1 is better under the requirements of a large eyebox and a large field angle, and the MTF values at the edges of the eyeboxes do not have a bottoming condition.
Fig. 15 shows the defocus curve at the center of the eye box, fig. 15 corresponds to fig. 13 described above, and the vertical line in the middle of fig. 13 is the position of the display screen 3 where the display screen 3 can achieve good imaging. Fig. 16 shows the defocus curve at the edge of the eye box, fig. 16 corresponds to fig. 14, the vertical line in the middle of fig. 16 is the position of the display screen, fig. 16 shows that the center position of the eye box is shifted, a good defocus effect is obtained by shifting the display screen 3 at the position of 7mm at the edge of the eye box, and it can be seen that the MTF value is decreased outside the vertical line in the middle.
According to another aspect of the embodiments of the present application, there is also provided a wearable device, which includes a housing and the optical module as described above, where the optical module is disposed on the housing.
The wearable device is, for example, a VR headset including VR glasses or a VR helmet, and the like, and this is not particularly limited in this application.
For example, the housing is a mirror holder, and two mirror frames are arranged on the mirror holder; the optical module sets up to two, two the optical module group is established in two picture frames.
The specific implementation of the head-mounted display device in the embodiment of the present application may refer to each embodiment of the optical module, so that all beneficial effects brought by the technical solutions of the embodiments are at least achieved, and details are not repeated here.
In the above embodiments, the differences between the embodiments are described with emphasis, and different optimization features between the embodiments may be combined to form a better embodiment as long as the differences are not contradictory, and in consideration of the brevity of the text, no further description is given here.
Although some specific embodiments of the present application have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for purposes of illustration and is not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.
Claims (14)
1. An optical module is characterized by comprising an imaging lens group, a light splitting element (5), a phase retarder (6) and a polarization reflecting element (7) which are arranged in the imaging lens group; wherein the phase retarder (6) is located between the light splitting element (5) and the polarization reflective element (7);
the optical module further comprises a display screen (3), the display screen (3) is arranged on one side of the imaging lens group and is located on the same optical axis with the imaging lens group, and the display screen (3) can move along the optical axis direction relative to the imaging lens group so as to adjust the rear intercept of the optical module;
the optical module satisfies: the absolute distance | D (x) | of the display screen (3) moving along the optical axis direction is proportional to the space position x of the eye box.
2. The optical module according to claim 1, wherein the distance D (x) of movement of the display screen (3) in the direction of the optical axis and the spatial position x of the eye box satisfy a downward opening parabolic relationship: x is the number of 2 ＝-2*p*(D(x)-d)；
Wherein x belongs to R, D (x) is less than or equal to D, D is the distance between the imaging lens group of the display screen (3) corresponding to the center position of the eye box, D is greater than 0,p and is the distance between the focus of the parabola and the parabola directrix, p is greater than 0, the coordinate of the focus is (0,d-p/2), and the directrix equation is y = p/2+d.
3. The optical module according to claim 1, wherein the distance D (x) of movement of the display screen (3) in the direction of the optical axis and the spatial position x of the eye box satisfy the following functional equation: d (x) = p1 x 6 +p2*x 5 +p3*x 4 +p4*x 3 +p5*x 2 +p6*x+p7；
Wherein-1.3 e -07 ＜p1＜-1.0e -05 ，-1.2e -06 ＜p2＜-1.0e -04 ，-1.1e -05 ＜p3＜-1.0e -03 ，-1.3e -05 ＜p4＜-1.0e -02 ，-1.2e -05 ＜p5＜-1.0e -02 ，-1.1e -05 ＜p6＜-1.0，1.5＜p7＜50；
x represents the radial distance from any position of the eye box to the center of the eye box, x =0 represents the center position of the eye box, x <0 represents the spatial position of the eye box along the negative direction by taking the center of the eye box as a datum point, x >0 represents the spatial position of the eye box along the positive direction by taking the center of the eye box as a datum point, and p7 is the distance from the side, close to the display screen (3), of the imaging lens group to the display screen (3).
4. The optical module according to claim 3, wherein the imaging lens group formed by any lens is formed by a function equation satisfied by a moving distance D (x) of the display screen (3) along the optical axis and a spatial position x of the eye box, and satisfies: data fitting R 2 ≥0.95。
5. The optical module according to claim 1, further comprising an eye tracking assembly (9), wherein the eye tracking assembly (9) is disposed adjacent to the imaging lens group;
the eyeball tracking assembly (9) is used for acquiring eyeball position information of a wearer and controlling and adjusting the distance between the display screen (3) and the imaging lens group.
6. The optical module according to claim 1, wherein the display screen (3) is configured to emit circularly polarized light to the imaging lens group, and a side of the display screen (3) close to the imaging lens group is a light exit side, and the light exit side is provided with a screen protection device (4).
7. The optical module of claim 1, wherein the imaging lens group comprises at least one lens, and the surface shape of the lens comprises a plane surface, a spherical surface, an aspherical surface, a fresnel surface or a free-form surface.
8. Optical module according to claim 1, in which the set of imaging lenses comprises a first lens (1) and a second lens (2), the second lens (2) being located between the first lens (1) and the display screen (3);
the light splitting element (5) is arranged on any side of the second lens (2), and the phase retarder (6) and the polarization reflection element (7) are arranged on any side of the first lens (1).
9. The optical module according to claim 8, wherein the beam splitting element (5) is disposed on a surface of the second lens (2) close to the display screen (3);
the optical module further comprises a polarizing element (8), the phase retarder (6), the polarization reflecting element (7) and the polarizing element (8) are sequentially stacked to form an overlapped element (10), and the overlapped element (10) is arranged on the surface, away from the display screen (3), of the first lens (1).
10. An optical module according to claim 8, characterised in that the fast axis direction of the light-splitting element (5) forms an angle of 45 degrees with the transmission direction of the polarising reflective element (7).
11. Optical module according to claim 8 or 9, in which the polarization direction of the polarizing element (8) is the same as the polarization transmission direction of the polarizing reflective element (7).
12. The optical module of claim 1, wherein the optical module satisfies: the total system length TL of the optical module and the caliber D of the maximum lens in the imaging module max Ratio of (TL/D) 0.4 max ＜0.9。
13. The optical module of claim 1 wherein the effective focal length EFFL is: 13mm < EFFL < 33mm.
14. A wearable device, comprising:
a housing; and
the optical module of any of claims 1-13 disposed in the housing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211710211.5A CN115981003A (en) | 2022-12-29 | 2022-12-29 | Optical module and wearable equipment |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211710211.5A CN115981003A (en) | 2022-12-29 | 2022-12-29 | Optical module and wearable equipment |
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| CN115981003A true CN115981003A (en) | 2023-04-18 |
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| CN202211710211.5A Pending CN115981003A (en) | 2022-12-29 | 2022-12-29 | Optical module and wearable equipment |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116679458A (en) * | 2023-08-03 | 2023-09-01 | 歌尔光学科技有限公司 | Optical module and head-mounted display device |
| CN117289472A (en) * | 2023-11-27 | 2023-12-26 | 玩出梦想(上海)科技有限公司 | Optical module and head-mounted display device |
-
2022
- 2022-12-29 CN CN202211710211.5A patent/CN115981003A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116679458A (en) * | 2023-08-03 | 2023-09-01 | 歌尔光学科技有限公司 | Optical module and head-mounted display device |
| CN116679458B (en) * | 2023-08-03 | 2023-11-07 | 歌尔光学科技有限公司 | Optical module and head-mounted display device |
| CN117289472A (en) * | 2023-11-27 | 2023-12-26 | 玩出梦想(上海)科技有限公司 | Optical module and head-mounted display device |
| CN117289472B (en) * | 2023-11-27 | 2024-04-09 | 玩出梦想(上海)科技有限公司 | Optical system and head-mounted display device |
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