US2018045964A1PendingUtilityA1
Large exit pupil wearable near-to-eye vision systems exploiting freeform eyepieces
Est. expiryAug 12, 2036(~10.1 yrs left)· nominal 20-yr term from priority
Inventors:Frank JonesJames Benson BacqueRobert G. HilkesMehdi Arezoomand ErsdhadiMark HarrisJon Pawson
G06F 1/163G02B 2027/0123G02B 27/0172G02B 2027/0187G02B 2027/0178G02B 27/0179
47
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Claims
Abstract
Within applications for Near-to-Eye (NR2I) displays, irrespective of whether they are for short-term, long-term, low vision, augmented reality, etc., there is a conflicting tradeoff between user comfort, ease of attachment, minimizing intrusiveness and aesthetics which must be concurrently balanced with and are often in conflict with providing an optical vision system within the NR2I display that provides the user with a wide field of view and high image resolution whilst also offering a large exit pupil for eye placement with sufficient eye clearance. Embodiments of the invention address these issues and provide a high performance optical system through the design of the optical eyepiece design to overcome these limitations within a bioptic configuration with laterally disposed displays.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A near-to-eye (NR2I) display system comprising:
an assembly comprising:
a free-form prism lens,
a microdisplay for projecting image-light onto a predetermined region of a first surface of said freeform prism-lens, said image light performing two internal reflections within the free-form prism-lens before exiting the free-form prism-lens for viewing by the user with an eye, wherein
the microdisplay is fixedly held in position by said assembly relative to said first surface of the free-form prism lens and proximate a temple of the user nearest the user's eye viewing the projected image-light, such assembly having attachment features such that lateral motion of the assembly across the user's horizontal field of view when attached to a body of the NR2I system is made possible.
2 . The NR2I display system according to claim 1 , further comprising
a second assembly comprising
a second free-form prism lens;
a second microdisplay for projecting image-light onto a predetermined region of a first surface of said second freeform prism-lens, said image light performing two internal reflections within the second freeform prism-lens before exiting the second freeform prism-lens for viewing by the user with their other eye, wherein
the second microdisplay is fixedly held in position relative to said first surface of the second free-form prism lens and proximate the user's other temple by said second assembly, such assembly having attachment features such that lateral motion of the second assembly across the user's horizontal field of view when attached to the body of the NR2I system is made possible allowing the positions and separation of the assembly and second assembly to be established in dependence upon the positions and the inter-pupil distance of the user's eyes.
3 . The NR2I display system according to claim 1 , wherein
the first surface of the free-form prism-lens is defined by a surface that is at least one of non-rotationally symmetric and has non-symmetric features and is configured to transmit the received light from the microdisplay into the body of the free-form prism-lens and towards a second surface of said free-form prism-lens; the second surface of the free-form prism-lens is defined by a surface that is at least one of non-rotationally symmetric and has non-symmetric features and is configured to internally reflect over a first portion of the second surface light from the micro display entering the prism-lens through the first surface towards a third surface of the freeform prism-lens and configured to transmit over a second portion of the second surface light reflected from the second surface towards the user's eyes; and the third surface of the free-form prism-lens is configured to receive the light reflected by the first portion of the second freeform surface and internally reflect the light back towards the second portion of the second freeform surface, wherein the freeform prism-lens is oriented such that this internal folding of the light occurs along the same orientation as the wider horizontal field of view of the display.
4 . The NR2I display system according to claim 3 , wherein the first and second predetermined regions of the second surface overlap.
5 . The NR2I display system according to claim 1 , wherein
the freeform prism-lens has a center-field effective f-number (F/#) of less than 3.5 and an exit pupil diameter of at least 8 mm;
6 . The NR2I display system according to claim 1 , wherein
at least one of the freeform surfaces of the freeform prism-lens is described by an axially asymmetric quadratic and a set of orthogonal polynomials:
z
(
x
,
y
)
=
c
xx
x
2
+
2
c
xy
xy
+
c
yy
y
2
1
+
1
-
γ
(
c
xx
x
2
+
2
c
xy
xy
+
c
yy
y
2
)
+
∑
n
=
0
N
∑
k
=
0
n
b
n
n
-
2
k
W
n
n
-
2
k
(
x
/
r
0
,
y
/
r
0
)
where z is the sag along the local z-axis, x and y are the coordinates in the local coordinate system, c xx , c yy , and c xy are the curvature tensor at the origin, γ is a conic-like constant, r 0 is the radius of the surface, and the orthogonal polynomials on the unit circle are expressed as W n m (u,v)=Q n m (ρ)cos(mθ) and W n −m (u,v)=Q n m (ρ)sin(mθ) and u=ρ sin θ v=ρ cos θ.
7 . The NR2I display system according to claim 3 , wherein
a sub-portion of the first portion of the second surface of the freeform prism-lens that does not overlap the second portion of the second surface of the freeform prism-lens is at least one of coated with a reflective material, coated with a material to block external light entering the freeform prism, and covered by an opaque portion of an assembly containing the freeform prism-lens so as to block external light from entering the freeform prism-lens through said non-overlapping sub-portion.
8 . The NR2I display system according to claim 3 , wherein
the third freeform surface of the freeform prism-lens is mirrored to increase its reflectivity.
9 . The NR2I display system according to claim 3 , wherein
an auxiliary lens is disposed proximate to the third freeform surface of the freeform prism, the auxiliary lens being configured to minimize at least one of optical distortion and optical image displacement of a real-world scene viewed by the user through the freeform prism-lens and auxiliary lens.
10 . The NR2I display system according to claim 9 , wherein
the auxiliary lens has a surface towards the user's eye that has the same surface geometry as third freeform surface of the free-form prism-lens and is disposed in optical contact with the third freeform surface of the prism-lens.
11 . The NR2I display system according to claim 1 , wherein
the eye-clearance is at least 18 mm.
12 . The NR2I display system according to claim 1 wherein
the field-of view is at least one of greater than or equal to 28 degrees in the horizontal and greater than or equal to 21 degrees in the vertical.
13 . The NR2I display system according to claim 1 , wherein
at least one of:
the spatial distortion at maximum field angle is less than 10%;
the effective focal length is less than 20 mm;
vignetting at the maximum field positions is less than 40%;
the microdisplay has a pixel pitch greater than or equal to 7.5 microns (7.5 μm); and
the modulation transfer function across the user's field of view is greater than 30% at the spatial frequency of 33 line-pairs/mm and greater than 10% at the spatial frequency of 50 line-pairs/mm.
14 . The NR2I display system according to claim 1 , wherein
at least one of:
the design of the freeform prism-lens constrains the white-light distortion-limit to within a predetermined limit but the variation in distortion with wavelength is left unconstrained; and
total internal reflection of light received from the first freeform surface of the prism-lens by the second freeform surface of the prism-lens towards the third freeform surface of the prism-lens is achieved without the application of any mirroring to the second such freeform surface.
15 . The NR2I display system according to claim 1 , wherein
a displayed image is dynamically digitally laterally translated according to a measure of the distance from the user to an object of their focus in order to induce inward rotation of the user's eyes as the object draws nearer.
16 . The NR2I display system according to claim 15 , wherein
the amount of lateral translation is a function of at least one of the micro-display width, the distance to the viewed object, and the horizontal angular field of view of the NR2I display.
17 . The NR2I display system according to claim 1 , wherein
the images are translated in at least one of the horizontal and vertical directions according to at least one of the user's direction of gaze found through eye-tracking, range-finding data, and the displayed image data itself.
18 . A near-to-eye (NR2I) display system comprising:
an assembly comprising:
a free-form prism lens; and
a microdisplay for projecting image-light onto a predetermined region of a first surface of said freeform prism-lens, said image light performing two internal reflections within the free-form prism-lens before exiting the free-form prism-lens for viewing by the user with an eye, wherein
the microdisplay is fixedly held in position by said assembly relative to said first surface of the free-form prism lens and proximate a temple of the user nearest the user's eye viewing the projected image-light, such assembly having attachment features such that vertical angular motion of the assembly across the user's vertical field of view when attached to a body of the NR2I system is made possible, in order to allow positioning of the display above the user's line of sight.
19 . A near-to-eye (NR2I) display system comprising:
an assembly comprising:
a free-form prism lens; and
a microdisplay for projecting image-light onto a first surface of said freeform prism-lens, said image light projecting onto a second surface of said freeform prism-lens performing a first internal reflection to a third surface of the freeform prism-lens, a second internal reflection from the third surface towards a predetermined region of the second surface whereupon the light exits the freeform prism-lens towards the user's eye through said predetermined region; wherein
external light is prevented from entering substantially all the second surface excluding said predetermined region through at least one of an applied coating to the second surface of the freeform prism-lens and opaque structures external to the freeform prism-lens.Cited by (0)
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