CN106772717B - A kind of Fresnel Lenses and virtual reality device - Google Patents
A kind of Fresnel Lenses and virtual reality device Download PDFInfo
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- CN106772717B CN106772717B CN201611239469.6A CN201611239469A CN106772717B CN 106772717 B CN106772717 B CN 106772717B CN 201611239469 A CN201611239469 A CN 201611239469A CN 106772717 B CN106772717 B CN 106772717B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/02—Simple or compound lenses with non-spherical faces
- G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
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- G02B27/0172—Head mounted characterised by optical features
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Abstract
The invention discloses a kind of Fresnel Lenses and virtual reality devices, under the premise of meeting short focus, to reduce the size of Fresnel Lenses.Fresnel Lenses of the invention includes the Fresnel surface of basal plane and covering basal plane, and Fresnel surface is equipped with multiple sequentially connected sawtooth concentric rings, and the focal length of Fresnel surface is greater than 30mm, so that the focal length of Fresnel Lenses is less than 30mm.Focal length by the way that Fresnel surface is arranged is greater than 30mm, minimizes the focal length of basal plane, that is, increases the focal power of basal plane, and then the whole focal length of Fresnel Lenses is reduced within 30mm.Since Fresnel surface can still be made very thin under short focus, the integral thickness of Fresnel Lenses is thinning, realizes Fresnel Lenses and is provided simultaneously with short focus and small size.Based on this, Fresnel Lenses is applied in virtual reality device, to realize the lightening of virtual reality device.
Description
Technical field
The present embodiments relate to virtual reality image optics technical field more particularly to a kind of Fresnel Lenses and virtually
Real device.
Background technique
In recent years, virtual reality (Virtual Reality, abbreviation VR) technology is a kind of information generated based on computer
Interaction, the vision virtual environment with certain feeling of immersion, human eye is by lens inspection screen, the image seen by right and left eyes
Visual field is inconsistent, so as to see stereo-picture.
The principle of VR equipment is that the nearby image for generating display is drawn by optical system to distant place amplification, is almost full of
The field range of people, to generate feeling of immersion.Since the field range of human eye is very wide, so in order to guarantee enough visual angles,
By y=f*tan (w/2) (wherein y is object height, and w is visual angle, and f is focal length) it is found that the situation constant in the high y of object (screen size)
Under, the combined focal length of a whole set of optical system of use is had to sufficiently small, just can guarantee that visual angle is sufficiently large, while to guarantee to regard
Angle is sufficiently large, also to guarantee that the size of lens is sufficiently large, but the size of lens will increase greatly very much wearer's burden.Virtually existing
In real equipment, focal length, visual field, between lens thickness there are certain restricting relation, single lens meet big visual field, short focus simultaneously
It is very difficult away from, thin lens thickness.
In order to guarantee VR equipment comforts of use, the weight of the equipment must be light enough, while showing the matter of image
Amount also must be sufficiently high, cannot have excessive aberration to generate, while in order to guarantee feeling of immersion, the visual angle of VR be must assure that at 80 °
More than.Current solution main on the market is using monolithic non-spherical lens, however, to ensure that the quality of image, aspheric
The focal length of face lens cannot be too small, is generally greater than 35mm, no matter lateral or longitudinal which results in entire display equipment
Size is all bigger, and the thickness of eyeglass is also very thick.
To sum up, for existing VR lens when guaranteeing big visual angle, the size of VR lens is larger, is unfavorable for the lightening of VR equipment.
Summary of the invention
The present invention provides a kind of Fresnel Lenses and virtual reality device, to solve VR lens existing in the prior art
When guaranteeing big visual angle, the size of VR lens is larger, is unfavorable for the lightening problem of VR equipment.
The embodiment of the present invention provides a kind of Fresnel Lenses, the Fresnel surface including basal plane and the covering basal plane, described
Fresnel surface is equipped with multiple sequentially connected sawtooth concentric rings, and the focal length of the Fresnel surface is greater than 30mm, so that the phenanthrene
The focal length of Nie Er lens is less than 30mm.
Optionally, the focal power of the basal planeMeet following relationship:
Wherein, Φ is the focal power of the Fresnel Lenses, and f is the focal length of the Fresnel Lenses, and n' is the luxuriant and rich with fragrance alunite
The refractive index of your lens, n is air refraction, n2' be the Fresnel surface refractive index, D is that the Fresnel Lenses has
Imitate bore.
Optionally, effective aperture D >=22mm of the Fresnel Lenses.
Optionally, for the radial interannular of the multiple sawtooth concentric ring away from unequal, the multiple sawtooth concentric ring includes position
The 1st ring in the Fresnel surface center, and be arranged concentrically with the 1st ring and be successively arranged outward the 2nd ring, the 3rd
Ring ... G ring, wherein G is positive integer, and G >=4.
Optionally, as G=4, the outer diameter of the 1st ring is not less than 4.2mm, and the outer diameter of the 2nd ring is not less than
6.4mm, the outer diameter of the 3rd ring are not less than 7.8mm, and the outer diameter of the 4th ring is not less than 13.9mm.
Optionally, as G=4, the visual angle of the 1st ring is 0~20 °, and the visual angle of the 2nd ring is 20~30 °, described
The visual angle of 3rd ring is 30~36 °, and the visual angle of the 4th ring is 36~60 °.
Optionally, the annular region between the 3rd ring and the 4th ring is provided with multiple subrings, the multiple subring
It is concentric with the 3rd ring.
Optionally, the center thickness of the Fresnel Lenses is 3~7mm.
Optionally, the edge thickness of the Fresnel Lenses is greater than or equal to 1.5mm.
Optionally, the basal plane is spherical surface or aspherical.
The embodiment of the present invention also provides a kind of virtual reality device, including any of the above-described kind of Fresnel Lenses.
The Fresnel Lenses of present invention short focus in order to obtain, minimizes the focal power of Fresnel surface, and it is luxuriant and rich with fragrance to pass through setting
The focal length in the face Nie Er is greater than 30mm, can be reduced to the focal power of Fresnel surface in suitable range, the focal power of Fresnel surface
When as small as possible, basal plane can distribute more focal power, so as to reduce the focal length of basal plane in OK range, and then by luxuriant and rich with fragrance alunite
The whole focal length of your lens reduces within 30mm, since Fresnel surface can still be made very thin under short focus, so that luxuriant and rich with fragrance alunite
Your integral thickness of lens is thinning, realizes Fresnel Lenses and is provided simultaneously with short focus and small size.Based on this, Fresnel Lenses is answered
In virtual reality device, to realize the lightening of virtual reality device.
Detailed description of the invention
Attached drawing is used to provide further understanding of the present invention, and constitutes part of specification, is implemented with the present invention
Example is used to explain the present invention together, is not construed as limiting the invention.In the accompanying drawings:
Fig. 1 is the structural schematic diagram of Fresnel Lenses provided in an embodiment of the present invention；
Fig. 2 is the structural schematic diagram of Fresnel Lenses provided in an embodiment of the present invention；
Fig. 3 is the structural schematic diagram of each ring of Fresnel surface provided in an embodiment of the present invention；
Fig. 4 is the structural schematic diagram of Fresnel Lenses provided in an embodiment of the present invention；
Fig. 5 is the schematic diagram of each ring of Fresnel Lenses provided in an embodiment of the present invention and the corresponding relationship at visual angle；
Fig. 6 is the imaging optical path schematic diagram of Fresnel Lenses provided in an embodiment of the present invention；
Fig. 7 is that the MTF of Fresnel Lenses provided in an embodiment of the present invention analyzes result schematic diagram；
Fig. 8 is that the light efficiency of Fresnel Lenses provided in an embodiment of the present invention analyzes schematic diagram.
Specific embodiment
In order to which technical problem, technical solution and beneficial effect solved by the invention is more clearly understood, tie below
Closing Figure of description, preferred embodiment of the present invention will be described, it should be understood that preferred embodiment described herein is only used
In the description and interpretation present invention, it is not intended to limit the present invention.And in the absence of conflict, the embodiment in the application and
Feature in embodiment can be combined with each other.
In order to guarantee the quality of image, apply the focal length of the optical lens in virtual reality device cannot be too small, generally
It is greater than 35mm, and the thickness of eyeglass is also very thick, about 10~20mm or so, no matter laterally which results in entire VR equipment
Or longitudinal size is all bigger, and excessive volume brings extremely undesirable user experience.It is small in order to improve user experience
Type, lightweight are virtual display device urgent problems.
Traditional Fresnel Lenses includes Fresnel surface and a plane, has light-weight, small in size feature, very short
Focal length in the case where, still can be made thin, one third of the thickness less than typical aspheric thickness.But Fresnel
The shortcomings that lens is that aberration correcting capability is weaker, especially the aberration of picture fringe region.In addition, traditional Fresnel Lenses packet
A basal plane and Fresnel surface are included, Fresnel surface is made of multiple interannulars away from equal concentric loop, and each concentric loop includes
Second surface (also referred to as working face) and first surface (also referred to as non-working surface), first surface perpendicular to basal plane, basal plane be perpendicular to
The plane of optical axis, first surface connect with the second surface of arcuation, since the first surface between adjacent ring can also be such that light penetrates,
A part of light loss is caused, and the light penetrated from first surface also can form crosstalk to effective light of second surface, be used in VR
Picture is unintelligible when equipment, and eyes weak vibrations cause picture to generate violent smear so that the disadvantages of stronger spinning sensation.
In order to effectively reduce the volume of the optical lens in VR equipment, the embodiment of the invention provides be applied to VR equipment
One of novel Fresnel Lenses, be provided simultaneously with smaller short focus, size, effective aberration correction and the spy for weakening spinning sensation
Point.
Fresnel Lenses provided in an embodiment of the present invention is single lens, and referring to Fig.1, Fig. 2 and Fig. 3 are shown, including basal plane
1 and the Fresnel surface 2 of the basal plane 1 is covered, referring to Fig. 6, in optical system, Fresnel Lenses installation provided in this embodiment
Between the pupil and display screen of viewer, wherein display screen is the display device for launching virtual reality image, 1 direction of basal plane
The pupil side of viewer.The shape of basal plane 1 is spherical surface or aspherical, and Fresnel surface 2 is equipped with multiple sequentially connected saws
Tooth concentric ring, each sawtooth concentric ring include first surface 22 and second surface 21, it is contemplated that processing and non-working surface light loss
Mistake rate, it is 0 to 5 degree that the optical axis of first surface 22 and Fresnel Lenses, which is formed by acute angle, i.e., the optical axis of Fresnel Lenses is the
It is 0 to 5 degree, one end connection of first surface 22 that projection on one surface 22, which is formed by acute angle with the optical axis with Fresnel Lenses,
Fresnel surface 2, the other end connect second surface 21, and second surface 21 is arc.
The Fresnel Lenses of present invention short focus in order to obtain, minimizes the focal power of Fresnel surface 2, and it is luxuriant and rich with fragrance to pass through setting
The focal length in the face Nie Er 2 is greater than 30mm, can be reduced to the focal power of Fresnel surface 2 in suitable range, the light focus of Fresnel surface 2
When spending as small as possible, basal plane 1 can distribute more focal power, so as to reduce the focal length of basal plane 1 in OK range, and then will
The whole focal length of Fresnel Lenses reduces within 30mm, since Fresnel surface 2 can still be made very thin under short focus, so that
The integral thickness of Fresnel Lenses is thinning, realizes Fresnel Lenses and is provided simultaneously with short focus and small size.
The shape of the Fresnel Lenses of this programme embodiment can be designed according to structure needs to be fabricated to arbitrary shape (such as circle
Shape, rectangular, oval, polygon etc.), the lens material used is mainly optical plastic, can be PMMA, the materials such as PC, COC
Material, but it is not limited to these types of material.The embodiment of the present invention is illustrated by taking circular Fresnel Lenses as an example.
It is combined using basal plane 1 with Fresnel surface 2, and the focal power in two faces is allowed to reach reasonable distribution, make lens short
In burnt, frivolous situation, the image quality that can have still had, less misty sense.The embodiment of the present invention provides a kind of reasonable distribution
The focal power of basal plane 1 and Fresnel surface 2 obtains the alternative embodiment of short focus Fresnel Lenses.
It is combined using basal plane 1 with Fresnel surface 2, and the focal power in two faces is allowed to reach reasonable distribution, so that Fresnel
The focal length of lens reduces the alternative embodiment within 30mm, specifically includes:
First, when distributing the focal power of basal plane 1 and Fresnel surface 2, allow the focal power of Fresnel surface 2 small as far as possible, basal plane 1
Focal power is big.
This is because the first surface 22 of Fresnel surface 2 directly affects the transmitance and image quality of light, Fresnel surface 2
The focal power undertaken is bigger, and the area of the first surface 22 of Fresnel surface 2 is also bigger, and light loss is more severe, and at this time first
Surface 22 is also more serious to the crosstalk of second surface 21, so that overall picture has a kind of misty sense, influences the visual experience of people.
Under the premise of meeting thickness and visual angle, magnifying power requirement, the focal power that Fresnel surface 2 undertakes is smaller, is more conducive to reduce light loss
It loses, promotes image sharpness, weaken misty sense, be also more conducive to process.
Second, when the focal power of Fresnel surface 2 is as small as possible, the focal length of Fresnel surface 2 is at least greater than 30mm, and luxuriant and rich with fragrance
Effective aperture D of the focal length in the face Nie Er 2 at least more than Fresnel Lenses.Specific reason is as follows:
In general, it is suitble to the focal length of the Fresnel surface 2 of imaging to should be greater than 30mm, simultaneously, it is contemplated that Fresnel Lenses
Limitation of the effective aperture D to the radius of curvature of Fresnel surface 2, the radius of curvature of Fresnel surface 2 determine the focal length of Fresnel surface 2
F2, so the radius of curvature of Fresnel surface 2 is at least greater than D/2, i.e. the focal length of Fresnel surface 2 is greater than or is equal to D.
So the focal length of Fresnel surface 2 should meet greater than 30mm simultaneously and be greater than the effective aperture D of Fresnel Lenses.
Third, the maximum focal power being capable of providing according to Fresnel surface 2, it may be determined that the minimum power of basal plane 1；
Relational expression existing for the focal power of Fresnel surface 2 and the focal length of Fresnel surface 2 are as follows:Wherein, n2' it is luxuriant and rich with fragrance
The refractive index in the face Nie Er 2, f2 are the focal length of Fresnel surface 2.Therefore, it according to the minimum value of the focal length of Fresnel surface 2, can determine
The maximum focal power that Fresnel surface 2 is capable of providing out, i.e.,(or)；
And the whole focal power of Fresnel Lenses and focal power, the focal power of Fresnel surface 2 of basal plane 1 meet relational expressionWherein, Φ is the whole focal power of Fresnel Lenses,For the focal power of basal plane 1,For Fresnel surface 2
Focal power.
Therefore, the maximum focal power being capable of providing according to Fresnel surface 2 determines the minimum power of basal plane 1, i.e.,Wherein Φ is the focal power of Fresnel Lenses, n2' be Fresnel surface 2 refractive index.
So optionally, the focal power of basal plane 1
4th, when the focal power of Fresnel surface 2 is as small as possible, basal plane 1 is determined according to the effective aperture D of Fresnel Lenses
Maximum focal power.
In order to keep lens frivolous, the focal power of basal plane 1 cannot infinitely great and basal plane 1 focal length cannot be infinitely small, because
This, it is thus necessary to determine that the focal power of basal plane 1Maximum value, i.e. the minimum focus of basal plane 1.
At this point, the limitation in view of lowest calibre, radius of curvature of basal plane 1 of Fresnel Lenses etc. to the focal length of basal plane 1,
The focal power of basal plane 1Expression formula are as follows:Wherein,For the focal power of basal plane 1, n' is Fresnel Lenses
Refractive index, n are air refraction, and r is the radius of curvature of Fresnel Lenses.When the effective aperture of Fresnel Lenses is D, at this time
The minimum profile curvature radius of basal plane 1 is 0.5D, the maximum focal power of basal plane 1It is obtained in 1 radius of curvature minimum of basal plane, i.e.,Wherein,For the focal power of basal plane 1, n' is the refractive index of Fresnel Lenses, and n is air refraction, and D is luxuriant and rich with fragrance alunite
The effective aperture of your lens.
So optionally, the focal power of basal plane 1
Optionally, the minimum profile curvature radius of basal plane 1 is 0.8D, the focal power of basal plane 1
The content as described in above-mentioned first to fourth, it can be deduced that: the focal power ψ 1 of basal plane 1 meets following relationship:
Wherein, Φ is the focal power of Fresnel Lenses, and f is the focal length of Fresnel Lenses, n'
For the refractive index of Fresnel Lenses, n is air refraction, n2' be Fresnel surface 2 refractive index, D be Fresnel Lenses it is effective
Bore.
When focal power provided by Fresnel surface 2 is larger, the focal power that basal plane 1 provides is smaller, and refractive index of the same race
Under lens material, focal power is bigger, and focal length is smaller.
Further, according to the value of the focal power of basal plane 1, the value range of the focal length of basal plane 1 can be determined, so that luxuriant and rich with fragrance
The focal length of Nie Er lens reduces within 30mm.
Firstly, according toIt can determine the minimum power and maximum focal power of basal plane 1.
Secondly, there are following relationships for the focal power and the focal length of Fresnel Lenses of Fresnel Lenses:Wherein, n'
For the refractive index of Fresnel Lenses, f is the focal length of Fresnel Lenses.It therefore, can according to focal length f≤30mm of Fresnel Lenses
To determine the value of Φ.
Under normal circumstances Fresnel Lenses as a whole, so Fresnel surface 2 is identical with the refractive index of basal plane 1, i.e.,
N'=n1'=n2'。
Relational expression existing for the focal power of basal plane 1 and the focal length of basal plane 1 are as follows:Wherein, n1' be basal plane 1 refraction
Rate, f1 are the focal length of basal plane 1.According to the minimum power of basal plane 1 and maximum focal power, andIt can determine basal plane 1
Focal length maximum value and focal length minimum value.
To sum up, it is combined using basal plane 1 with Fresnel surface 2, and the focal power in two faces is allowed to reach reasonable distribution, make Fei Nie
The focal length of your lens reduces within 30mm, so that Fresnel Lenses has the characteristics of short focus.
Optionally, on the basis of Fresnel Lenses has short focus, the basal plane 1 in the embodiment of the present invention is spherical surface.
Preferably, the basal plane 1 in the embodiment of the present invention is aspherical, aspherical to can be very good correction picture relative to spherical surface
Difference.Based on basal plane 1 be it is aspherical, Fresnel Lenses can have biggish field angle, in order to meet biggish feeling of immersion, so
The maximum visual angle of Fresnel Lenses is at least 80 °.
On the basis of Fresnel Lenses has short focus, the embodiment of the invention also provides frivolous Fresnel Lenses.
Optionally, in order to keep Fresnel Lenses frivolous as far as possible, the horizontal and vertical size of Fresnel Lenses, a side need to be reduced
Face needs to reduce the effective aperture of Fresnel Lenses while meeting big visual angle；On the other hand, meeting the same of short focus
When, need to reduce the thickness of Fresnel Lenses.
On the one hand, field angle FOV >=80 ° of the Fresnel Lenses of the embodiment of the present invention, so Fresnel Lenses is effective
Bore D >=22mm.
Referring to Fig. 4, the effective aperture of Fresnel Lenses is the diameter D of Fresnel surface 2, the diameter of Fresnel surface 2As shown in figure 4, l is distance of the pupil to 1 center of basal plane of Fresnel Lenses, d is that Fresnel is saturating
The center thickness of mirror, w are the maximum visual angle of Fresnel Lenses, and the value of usual l is greater than or equal to 8mm, d in the embodiment of the present invention
Value range be 3~7mm, in order to meet biggish feeling of immersion, so the maximum visual angle of Fresnel Lenses is at least 80 °, i.e. w
Value is at least 80 °, optionally, if taking limiting value, l=10mm, d=3mm, w=80 ° of then D >=22mm.
On the other hand, it can still be made very thin under short focus due to the Fresnel surface of Fresnel Lenses 2, it can be with
The integral thickness of Fresnel Lenses is done it is thin, Fresnel Lenses whole focal length be less than 30mm while, Fresnel Lenses
Center thickness can reduce to 3~7mm, and then reduce the lateral volume of Fresnel Lenses.
In addition, Fresnel Lenses have short focus and it is frivolous while, Fresnel Lenses provided in an embodiment of the present invention is also
Has the characteristics of being easily worked.
Optionally, it is contemplated that the edge of Fresnel Lenses processes complexity, and the edge thickness of Fresnel Lenses is at least answered
Greater than 1mm or 1.5mm.
Optionally, in order to reduce Fresnel surface 2 first surface 22 difficulty of processing, multiple sawtooth of Fresnel surface 2 are same
The annulus depth of thimble is no more than 0.25mm, i.e. the working depth of the first surface 22 of sawtooth concentric ring is no more than 0.25mm.It is main
Want the reason is as follows that:
Since Fresnel Lenses is a kind of optical lens components with fine structure, it is by the concentric circles structure of a ring ring
At, concentric circles only remains the second surface that can generate refraction, therefore Fresnel Lenses can be made thin, but exactly
This fine structure, make Fresnel surface 2 processing there are certain difficulties.And in image optics, the annulus of Fresnel surface 2
Depth is restricted by the focal power of Fresnel surface 2, and focal power is bigger, and annulus depth is deeper, is processed more difficult.The above-mentioned implementation of the present invention
The focal power for reducing Fresnel surface 2 in example as far as possible also helps the first of each sawtooth concentric ring for reducing Fresnel surface 2
The working depth on surface 22.
Referring to Fig. 2, the annulus depth of Fresnel surface 2 is h, and optionally, the annulus depth h of each sawtooth concentric ring is not more than
0.25mm。
In order to guarantee that Fresnel surface 2 has preferable image quality, in the embodiment of the present invention, the Fresnel of Fresnel Lenses
The interannular of multiple sawtooth concentric rings in face 2 is away from unequal.
Because second surface 21 is the imaging surface of Fresnel surface 2, if interannular, away from equal, the depth of edge ring band is got over
Deep, too deep annulus depth will lead to ghost image and quality of optical imaging is deteriorated, while the area of first surface 22 is bigger, light loss
Also can be more severe, crosstalk is caused to the imaging of second surface 21, so that the imaging effect of second surface 21 is deteriorated, and then leads to phenanthrene
The optical imaging effect in the face Nie Er 2 is very poor.
Therefore, in order to guarantee that Fresnel surface 2 has preferable image quality, in the embodiment of the present invention, Fresnel Lenses
The interannular of multiple sawtooth concentric rings of Fresnel surface 2 is away from unequal.Multiple sawtooth concentric rings are made into unequal spacing, can be made
The annulus depth on one surface 22 is relatively uniform, and edge ring band will not be too deep, can effectively reduce the gross area of first surface 22, improves
Light utilization efficiency reduces the imaging crosstalk to second surface 21, and then improves the image quality of Fresnel surface 2.
In optional example, while Fresnel Lenses has short focus, frivolous and annulus depth no more than 0.25mm, Fei Nie
The interannular of multiple sawtooth concentric rings of the Fresnel surface 2 of your lens is away from unequal.
As shown in Figures 2 and 3, for the radial interannular of the multiple sawtooth concentric ring away from unequal, the multiple sawtooth is concentric
Ring includes the 1st ring positioned at 2 center of Fresnel surface, and the 2nd for being arranged concentrically and being successively arranged outward with the 1st ring
Ring, the 3rd ring ... G ring, wherein G is positive integer, and G >=4.
Specifically, the interannular of multiple sawtooth concentric rings is away from the outer diameter for depending on each concentric ring, the outer diameter of each concentric ring
Refer to the maximum gauge of each concentric ring.
Optionally, the outer diameter of sawtooth concentric ring is determined that sawtooth is concentric by the corresponding angular field of view of sawtooth concentric ring
The corresponding angular field of view of ring divides the image sensitivity in each visual angle according to human eye.Visual angle in the embodiment of the present invention refers to
Human eye watches the field angle when image of display screen projection by Fei Nier lens, and the corresponding visual angle of different sawtooth concentric rings refers to
Human eye watches the field angle when image of display screen projection by each sawtooth concentric ring region.
This is because human eye is more sensitive to image information in 10 degree of angulars field of view, it can in 10~20 ° of angulars field of view
It is more sensitive to dynamic image in 20~30 ° of degree angulars field of view correctly to identify image information.When the view of image vertical direction
Angle is 20 °, and when the visual angle of horizontal direction is 36 °, human eye just has extraordinary approach sense of vision, nor because frequently turns
Dynamic eyeball causes tired.
For example, it is contemplated that human eye to the highly sensitive of the image information within the scope of 20 ° of visual angle, therefore, the 1st ring of setting it is outer
Diameter is as big as possible, so that the corresponding visual angle of outer diameter of the 1st ring is at least 20 °, and should avoid the light in 20 ° of visual angle as far as possible
One surface 22 generates light efficiency loss, and first surface 22 is avoided to generate string to the image in 20 ° of 21 visual angle of second surface as far as possible
It disturbs.
Optionally, in the embodiment of the present invention, by the sensitizing range of human eye according to human eye to the susceptibility of image from high to low
It is divided into the first sensitizing range band, the second sensitizing range band, third sensitizing range band, the 4th sensitizing range band and the 5th sensitizing range
Domain band.
Optionally, the basal plane 1 of the Fresnel Lenses of the embodiment of the present invention and Fresnel surface 2 are rotationally symmetrical surf, and basal plane 1 is
Using the central point of basal plane 1 as the rotational symmetry figure of symmetrical centre；It is symmetrical that Fresnel surface 2, which is with the central point of Fresnel surface 2,
The rotational symmetry figure at center, wherein the central point of basal plane 1 and Fresnel surface 2 is coaxial.Based on this, human eye sensitivity region band with
The corresponding relationship of lens coverage can be set are as follows:
The corresponding visual angle of first sensitizing range band are as follows: horizontal direction, vertical direction are up to 0~20 °；
The corresponding visual angle of second sensitizing range band are as follows: horizontal direction, vertical direction are up to 20~30 °；
The corresponding visual angle of third sensitizing range band are as follows: horizontal direction, vertical direction are up to 30~36 °；
The corresponding visual angle of 4th sensitizing range band are as follows: horizontal direction, vertical direction are up to 36~60 °；
Human eye is lower in the susceptibility of the 5th sensitizing range band, the visual angle of horizontal direction, vertical direction can be greater than 60 degree
Angular field of view collectively as the 5th sensitizing range band.
Corresponding relationship based on human eye sensitivity region band and lens coverage, the corresponding angular field of view of sawtooth concentric ring can be found in
Fig. 5.As shown in figure 5, the visual angle of the 1st ring is 0~20 ° as G=4, the visual angle of the 2nd ring is 20~30 °, described
The visual angle of 3rd ring is 30~36 °, and the visual angle of the 4th ring is 36~60 °.The outer diameter of 1st ring is D1, and the outer diameter of the 2nd ring is
D2, the outer diameter of the 3rd ring are D3, and the outer diameter of the 4th ring is D4.
Based on above-mentioned corresponding relationship, the outer diameter of multiple sawtooth concentric rings of Fresnel surface 2 can be taken according to following example
Value, specifically:
Optionally, the 1st ring is enabled to correspond to the first sensitizing range band of human eye, the outer diameter of the 1st ring is D1, the i.e. outer diameter of the 1st ring
The corresponding maximum visual angle D1 is 20 °.
According to formulaW1=20 °, to guarantee human eye comfort level, l should be greater than 8mm, and d takes
4mm, then the outer diameter D 1 of the 1st ring is at least 4.2mm.
Optionally, the 2nd ring is enabled to correspond to the second sensitizing range band of human eye, the outer diameter of the 2nd ring is D2, the outer diameter D 2 of the 2nd ring
Corresponding maximum visual angle is 30 °.
According to formulaW2=30 °, l is greater than 8mm, and d takes 4mm, the outer diameter D 2 of the 2nd ring to
It is less 6.4mm.
Optionally, the 3rd ring is enabled to correspond to the third sensitizing range band of human eye, the outer diameter of the 3rd ring is D3, the outer diameter D 3 of the 3rd ring
Corresponding maximum visual angle is 36 °.
According to formulaW3=36 °, l is greater than 8mm, and d takes 4mm, the outer diameter D 3 of the 3rd ring to
It is less 7.8mm.
When the 4th ring corresponds to the 4th sensitizing range band of human eye, the outer diameter of the 4th ring is D4, and the outer diameter D 4 of the 4th ring is corresponding most
Big visual angle is 60 °.
According to formulaW4=60 °, l is greater than 8mm, and d takes 4mm, the outer diameter D 4 of the 4th ring to
It is less 13.9mm.
In the process of Fresnel surface 2, if the interannular of adjacent two ring is excessive away from changing, the ring of respective rings will lead to
Band depth is too deep, will lead to 2 first surface of Fresnel surface, 22 light loss increase and image ghost image because annulus is too deep, and consider
The annulus depth of each ring needs to be maintained at 0.25mm hereinafter, so needing the annular region setting between the 3rd ring and the 4th ring
There are multiple subrings, each subring and the 3rd ring are concentric, it be advisable with meeting the annulus depth of each ring no more than 0.25mm, for example, the
Annular region between 3 rings and the 4th ring is dotted line ring region in Fig. 3, the subring of multiple concentrics, referring to the dotted line ring in Fig. 3.
For example, referring to Fig. 3, it is assumed that the annular region where the 4th sensitizing range band, i.e. annular region packet between the 3rd ring and the 4th ring
Including the 4th subring to the n-th subring, then the area of first surface 22 is S=∑ π * (h4*D4+h5*D5+ ...+hn*Dn), wherein h4,
H5 ..., hn are the annulus depth of the 4th subring to the n-th subring respectively.The area of first surface is smaller, then light loss is fewer, so
Make the area of first surface 22 small as far as possible, and 0.25mm is not to be exceeded in the depth of multiple subrings.
Because human eye is lower in the susceptibility of the 5th sensitizing range band, so stroke of the annular region to the 5th sensitizing range band
Divide and do not specially require, the annulus depth of each ring of the annular region of the 5th sensitizing range band is only needed to be not more than 0.25mm.For
Fresnel Lenses is set to be provided simultaneously with short focus, small size, big visual angle, while in view of the difficulty of processing, therefore to luxuriant and rich with fragrance alunite
You carry out boundary Control by lens, to meet design and processing request.The boundary condition of Fresnel Lenses is as follows:
The first, the edge thickness of Fresnel Lenses is greater than 1mm；
The second, the center thickness of Fresnel Lenses is T, 3mm < T < 7mm
Third, the focal power of basal plane 1 areF is less than or equal to 30mm.
4th, annulus depth capacity h:h < 0.25mm of Fresnel surface 2；
The corresponding maximum visual angle of five, the 1st rings is 20 °；The corresponding maximum visual angle of 2nd ring is 30 °；3rd ring is corresponding most
Big visual angle is 36 °；The corresponding maximum visual angle of 4th ring is 60 °, and the 4th ring includes multiple concentric subrings.
6th, the outer diameter D 1 of the 1st ring of Fresnel surface 2 is greater than 4.2mm, and the outer diameter D 2 of the 2nd ring is greater than 6.4mm；Outside 3rd ring
Diameter D3 is greater than 7.8mm；4th ring outer diameter is greater than 13.9mm.
According to above-mentioned boundary condition, the face type for meeting the basal plane 1 of above-mentioned condition is simulated, and meet the phenanthrene of above-mentioned condition
The face type in the face Nie Er 2.
And basal plane 1 is identical as the fitting face type formula of Fresnel surface 2, specifically:
Wherein c is curvature, and k is circular cone coefficient, and α is corresponding coefficient, and z is rise, and r is the radius of x/y plane.
Optionally, the face shape parameter for meeting the basal plane 1 of above-mentioned boundary condition is referring to table 1.
Optionally, the face shape parameter for meeting the Fresnel surface 2 of above-mentioned boundary condition is referring to table 2.Table 1
| r | 31.24901 |
| c | 0 |
| k | 0 |
| α1 | 0 |
| α2 | -2.9620128e-05 |
| α3 | 2.4128641e-07 |
| α4 | -1.5530116e-09 |
| α5 | 5.7424283e-12 |
| α6 | -9.0294645e-15 |
| α7 | 0e+00 |
| α8 | 0e+00 |
Table 2
| r | 17.842 |
| c | 0 |
| k | -0.066276755 |
| α1 | 0 |
| α2 | -2.273e-05 |
| α3 | 3.384e-07 |
| α4 | -6.422e-09 |
| α5 | 5.275e-11 |
| α6 | -2.395e-13 |
| α7 | 5.506e-16 |
| α8 | -4.957e-19 |
According to the imaging optical path of the Fresnel Lenses of Fig. 6 simulation, according to the invertibity of optical path, display that pupil of human is seen
The image of the center and peripheral of screen is all apparent, basal plane 1 be it is aspherical, preferably correct aberration, therefore, the embodiment of the present invention
Fresnel Lenses image quality it is higher.
According to Fig. 7, Fresnel Lenses corresponding minimum mtf value at 30lp/mm is greater than 0.1, the resolution ratio of low frequency high frequency
It is all very high.
According to Fig. 8, in the light transmission light efficiency schematic diagram of Fresnel Lenses, central area light energy is extremely concentrated, and illustrates luxuriant and rich with fragrance alunite
Clarity is high at the center of your lens.
To sum up, the present invention is greater than 30mm by the focal length of setting Fresnel surface 2, minimizes the focal power of Fresnel surface 2,
And then reduce the whole focal length of Fresnel Lenses within 30mm, so that the short focus of Fresnel Lenses is realized, in this base
On plinth, since each second surface of Fresnel surface 2 can still be made very thin, the integral thickness of Fresnel Lenses under short focus
It is thinning, so that Fresnel Lenses is provided simultaneously with short focus and small size, on this basis, by the Fresnel surface 2 of Fresnel Lenses
Multiple sawtooth concentric rings are arranged to unequal spacing, ensure that the image quality of Fresnel surface 2.So the embodiment of the present invention provides
Fresnel Lenses meet short focus, it is frivolous in the case where, can still have good image quality.
The embodiment of the present invention also provides a kind of virtual reality device, including any of the above-described kind of Fresnel Lenses, Fresnel are saturating
The optical system that mirror and display screen are constituted is referring to Fig. 6, such as Fig. 6, and Fresnel surface 2 is towards display screen, and basal plane 1 is towards pupil of human.
It is of course also possible to optical system is deformed into Fresnel surface 2 towards pupil of human, basal plane 1 is towards display screen.
Based on the above-mentioned Fresnel Lenses with short focus, small size and high imaging quality, Fresnel surface 2 is minimized
Focal power, Fresnel Lenses is applied in virtual reality device, it can be achieved that the lightening of virtual reality device, short focus and
High imaging quality.
Although alternative embodiment of the invention has been described, created once a person skilled in the art knows basic
Property concept, then additional changes and modifications may be made to these embodiments.So it includes excellent that the following claims are intended to be interpreted as
It selects embodiment and falls into all change and modification of the scope of the invention.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (9)
1. a kind of Fresnel Lenses, the Fresnel surface including basal plane and the covering basal plane, the Fresnel surface is equipped with multiple
Sequentially connected sawtooth concentric ring, which is characterized in that the focal length of the Fresnel surface is greater than 30mm, so that the Fresnel Lenses
Focal length be less than 30mm；
The focal power of the basal planeMeet following relationship:
Wherein, Φ is the focal power of the Fresnel Lenses, and f is the focal length of the Fresnel Lenses, and n' is that the Fresnel is saturating
The refractive index of mirror, n are air refraction, n2' be the Fresnel surface refractive index, D be the Fresnel Lenses effective mouth
Diameter.
2. Fresnel Lenses as described in claim 1, which is characterized in that effective aperture D >=22mm of the Fresnel Lenses.
3. Fresnel Lenses as described in claim 1, which is characterized in that the radial interannular of the multiple sawtooth concentric ring is not away from
Equal, the multiple sawtooth concentric ring includes the 1st ring positioned at the Fresnel surface center, and with the 1st ring is concentric sets
Set and be successively arranged outward the 2nd ring, the 3rd ring ... G ring, wherein G is positive integer, and G >=4.
4. Fresnel Lenses as claimed in claim 3, which is characterized in that as G=4, the outer diameter of the 1st ring is not less than
4.2mm, the outer diameter of the 2nd ring are not less than 6.4mm, and the outer diameter of the 3rd ring is not less than 7.8mm, and the outer diameter of the 4th ring is not
Less than 13.9mm.
5. Fresnel Lenses as claimed in claim 4, which is characterized in that as G=4, the visual angle of the 1st ring is 0~
20 °, the visual angle of the 2nd ring is 20~30 °, and the visual angle of the 3rd ring is 30~36 °, the visual angle of the 4th ring is 36~
60°。
6. Fresnel Lenses as claimed in claim 5, which is characterized in that the annulus between the 3rd ring and the 4th ring
Domain is provided with multiple subrings, and the multiple subring and the 3rd ring are concentric.
7. such as Fresnel Lenses described in any one of claims 1 to 6, which is characterized in that the center of the Fresnel Lenses
With a thickness of 3~7mm.
8. Fresnel Lenses as claimed in claim 7, which is characterized in that the basal plane is spherical surface or aspherical.
9. a kind of virtual reality device, which is characterized in that including Fresnel Lenses such as described in any item of the claim 1 to 8.
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| CN109031661A (en) * | 2017-06-12 | 2018-12-18 | 宏碁股份有限公司 | Virtual reality display device |
| CN107144968B (en) * | 2017-06-30 | 2020-06-23 | 深圳超多维科技有限公司 | Virtual reality device |
| CN109507798A (en) * | 2017-09-15 | 2019-03-22 | 中强光电股份有限公司 | Nearly eye display device |
| CN111443479B (en) * | 2017-10-13 | 2022-05-24 | 玉晶光电(厦门)有限公司 | Eyepiece optical system |
| CN108287397B (en) * | 2018-01-15 | 2020-08-25 | 歌尔股份有限公司 | Optical axis calibration method of head-mounted display equipment |
| CN108196360A (en) * | 2018-02-05 | 2018-06-22 | 小派科技（上海）有限责任公司 | Eyepiece and the glasses equipped with eyepiece |
| US10609364B2 (en) * | 2018-04-06 | 2020-03-31 | Facebook Technologies, Llc | Pupil swim corrected lens for head mounted display |
| CN112424669B (en) * | 2018-07-24 | 2022-11-29 | 株式会社尼康 | Eyepiece optical system and head-mounted display |
| CN114859450B (en) * | 2022-05-23 | 2024-05-24 | 京东方科技集团股份有限公司 | Fresnel lens group and virtual reality device |
| CN114966918A (en) * | 2022-07-25 | 2022-08-30 | 允沃能源科学研究(江苏)有限公司 | Fresnel lens and imaging system with same |
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| CN104749762A (en) * | 2015-03-06 | 2015-07-01 | 成都理想境界科技有限公司 | Optical enlargement combination lens, head-mounted display optical system and equipment |
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