U.S. patent application number 14/419472 was filed with the patent office on 2015-07-02 for method for providing to an eye of a wearer a customizable ophthalmic lens and associated active system of vision.
The applicant listed for this patent is ESSILOR INTERNATIONAL (COMPAGNIE GENERALE D'OPTIQUE). Invention is credited to Marius Peloux.
Application Number | 20150185504 14/419472 |
Document ID | / |
Family ID | 47010439 |
Filed Date | 2015-07-02 |
United States Patent
Application |
20150185504 |
Kind Code |
A1 |
Peloux; Marius |
July 2, 2015 |
Method for Providing to an Eye of a Wearer a Customizable
Ophthalmic Lens and Associated Active System of Vision
Abstract
Providing to an eye a customizable ophthalmic lens comprising a
transparent set of electroactive cells (24) juxtaposed to a lens
surface for providing an optical phase-shift distribution function.
The method includes providing (402) a reference phase-shift
distribution function adapted to provide a given dioptric function
DF(.alpha., .beta.); determining (404) the actual gaze direction
(.alpha..sub.a, .beta..sub.a); choosing (406) a reference gaze
direction (.alpha..sub.R, .beta..sub.R); calculating (408) an
actual point P.sub.a at the intersection between the actual gaze
direction and the transparent set of electroactive cells, and a
reference point P.sub.R at the intersection between the reference
gaze direction and the transparent set of electroactive cells;
calculating (410) a modified phase-shift distribution function by
shifting the reference phase-shift distribution function according
to a vector {right arrow over (P.sub.RP.sub.a)}; and activating
(412) the electroactive cells according to the modified phase-shift
distribution function.
Inventors: |
Peloux; Marius; (Charenton
Le Pont, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ESSILOR INTERNATIONAL (COMPAGNIE GENERALE D'OPTIQUE) |
Charenton-Le-Pont |
|
FR |
|
|
Family ID: |
47010439 |
Appl. No.: |
14/419472 |
Filed: |
August 2, 2013 |
PCT Filed: |
August 2, 2013 |
PCT NO: |
PCT/EP2013/066335 |
371 Date: |
February 3, 2015 |
Current U.S.
Class: |
351/159.39 |
Current CPC
Class: |
G02C 7/083 20130101 |
International
Class: |
G02C 7/08 20060101
G02C007/08; A61B 3/113 20060101 A61B003/113 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2012 |
EP |
12305974.3 |
Claims
1. A method for providing to an eye of a wearer a customizable
ophthalmic lens comprising a transparent set of electroactive cells
juxtaposed to a surface of the said lens, said set of cells being
activable and suitable for providing an optical phase-shift
distribution function, every electroactive cell having dimensions
such that it can be fully comprised in a 70 .mu.m diameter circle,
the method comprising the steps of: providing a reference
phase-shift distribution function adapted to provide to the wearer
a given dioptric function DF(.alpha., .beta.), said reference
phase-shift distribution function being expressed with respect to a
reference point PR, the reference phase-shift function having a
null gradient at said reference point PR; determining the actual
gaze direction (.alpha..sub.a, .beta..sub.a) of the eye of the
wearer when wearing the customizable ophthalmic lens; choosing a
reference gaze direction (.alpha..sub.R, .beta..sub.R) for
positioning said reference point PR; calculating an actual point
P.sub.a and the reference point PR, said actual point Pa being the
intersection between the actual gaze direction of the eye of the
wearer and the transparent set of electroactive cells and said
reference point PR being located at the intersection between the
reference gaze direction of the eye of the wearer and the
transparent set of electroactive cells; calculating a modified
phase-shift distribution function by shifting the reference
phase-shift distribution function according to a vector; and
activating the electroactive cells according to said modified
phase-shift distribution function so as to provide a customized
ophthalmic lens to the eye of the wearer.
2. The method for providing to an eye of a wearer a customizable
ophthalmic lens according to claim 1, wherein said method further
comprises the steps of: providing a plurality of reference
phase-shift distribution functions adapted to provide to the wearer
a plurality of given dioptric functions DFn(.alpha., .beta.); and
choosing a reference phase-shift distribution function among the
plurality of reference phase-shift distribution functions depending
on the actual gaze direction (.alpha.a, .beta.a) of the eye of the
wearer when wearing the customizable ophthalmic lens.
3. The method for providing to an eye of a wearer a customizable
ophthalmic lens according to claim 1, wherein said method further
comprises the steps of: providing a plurality of reference
phase-shift distribution functions adapted to provide to the wearer
a plurality of given dioptric functions DF.sub.n(.alpha., .beta.);
determining an actual viewing distance of the eye of the wearer;
and choosing a reference phase-shift distribution function among
the plurality of reference phase-shift distribution functions
depending on the actual viewing distance of the eye of the
wearer.
4. The method for providing to an eye of a wearer a customizable
ophthalmic lens according to claim 1, wherein a reference
phase-shift distribution function is chosen from among a list of a
plurality of reference phase-shift distribution functions
consisting of: at least a reference phase-shift distribution
function adapted to provide to the wearer a given dioptric function
DFNV(.alpha., .beta.) suitable for near vision, at least a
reference phase-shift distribution function adapted to provide to
the wearer a given dioptric function DFFV(.alpha., .quadrature.)
suitable for far vision, at least a reference phase-shift
distribution function adapted to provide to the wearer a given
dioptric function DFIV(.alpha., .quadrature.) suitable for
intermediate vision.
5. The method for providing to an eye of a wearer a customizable
ophthalmic lens according to claim 3, wherein said method further
comprises the steps of: providing at least three reference
phase-shift distribution functions adapted to provide to the wearer
a given dioptric functions respectively suitable for near vision
DFNV(.alpha., .beta.), suitable for intermediate vision
DFIV(.alpha., .beta.) and suitable for far vision DFFV(.alpha.,
.beta.); determining an actual viewing distance of the eye of the
wearer; and choosing a reference phase-shift distribution function
among the at least three reference phase-shift distribution
functions depending on the actual viewing distance of the eye of
the wearer such that: if the actual viewing distance of the eye of
the wearer is in a first range, the reference phase-shift
distribution functions adapted to provide to the wearer a given
dioptric functions respectively suitable for near vision
DF.sub.NV(.alpha., .beta.) is chosen; if the actual viewing
distance of the eye of the wearer is in a second range greater than
the first range, the reference phase-shift distribution functions
adapted to provide to the wearer a given dioptric functions
respectively suitable for intermediate vision DF.sub.IV(.alpha.,
.beta.) is chosen; and if the actual viewing distance of the eye of
the wearer is in a third range greater than the second range, the
reference phase-shift distribution functions adapted to provide to
the wearer a given dioptric functions respectively suitable for far
vision DF.sub.FV(.alpha., .beta.) is chosen.
6. The method for providing to an eye of a wearer a customizable
ophthalmic lens according to claim 1, wherein the actual gaze
direction (.alpha..sub.a, .beta..sub.a) of the eye of the wearer
when wearing the customizable ophthalmic lens is determined by
tracking the pupil of the eye of the wearer thanks to an
eye-tracker device.
7. A computer program product comprising one or more stored
sequence of instructions that is accessible to a processor and
which, when executed by the processor, causes the processor to
carry out the steps of claim 1.
8. A computer readable medium storing one or more sequences of
instructions of the computer program product of claim 7.
9. An active system of vision for an eye of a wearer, said active
system of vision being adapted to be disposed in front of an eye of
a wearer and comprising: a customizable ophthalmic lens comprising
a transparent set of electroactive cells juxtaposed to a surface of
said lens, said set of cells being activable and suitable for
providing an optical phase-shift distribution function, every
electroactive cell having dimensions such that it can be fully
comprised in a 70 .mu.m diameter circle; a device adapted for
determining the actual gaze direction (.alpha..sub.a, .beta..sub.a)
of the eye of the wearer when wearing the customizable ophthalmic
lens; a processor operatively connected to the transparent set of
electroactive cells and to the device, wherein the processor is
configured to: provide a reference phase-shift distribution
function adapted to provide to the wearer a given dioptric function
DF(.alpha., .beta.), said reference phase-shift distribution
function being expressed with respect to a reference point PR, the
reference phase-shift function having a null gradient at said
reference point P.sub.R; choose a reference gaze direction
(.alpha..sub.R, .beta..sub.R) for positioning said reference point
P.sub.R; receive electrical signals dependent on the actual gaze
direction of the eye from said device; calculate an actual point
P.sub.a and the reference point P.sub.R, said actual point P.sub.a
being the intersection between the actual gaze direction of the eye
of the wearer and the transparent set of electroactive cells and
said reference point P.sub.R being located at the intersection
between the reference gaze direction of the eye of the wearer and
the transparent set of electroactive cells; calculate a modified
phase-shift distribution function by shifting the reference
phase-shift distribution function according to a vector {right
arrow over (P.sub.RP.sub.a)}; and activate the electroactive cells
according to the said modified phase-shift distribution function so
as to provide a customized ophthalmic lens to the eye of the
wearer.
10. The active system of vision according to claim 9, further
comprising another device adapted for measuring the actual viewing
distance of the eye of the wearer when wearing the customizable
ophthalmic lens.
11. The active system of vision according to claim 10, wherein said
another device comprises a telemeter adapted to measure the actual
viewing distance of the eye of the wearer when wearing the
customizable ophthalmic lens.
12. The active system of vision according to claim 9, wherein a
reference phase-shift distribution function is chosen from among a
list of a plurality of reference phase-shift distribution functions
consisting of: at least a reference phase-shift distribution
function adapted to provide to the wearer a given dioptric function
DFNV(.alpha., .beta.) suitable for near vision, at least a
reference phase-shift distribution function adapted to provide to
the wearer a given dioptric function DFFV(.alpha., .beta.) suitable
for far vision, at least a reference phase-shift distribution
function adapted to provide to the wearer a given dioptric function
DFFV(.alpha., .beta.) suitable for far vision, at least a reference
phase-shift distribution function adapted to provide to the wearer
a given dioptric function DFIV(.alpha., .beta.) suitable for
intermediate vision.
13. The active system of vision according to claim 9, wherein said
device is disposed on a face of the transparent set of
electroactive cells facing the eye.
14. The active system of vision according to claim 9, wherein: said
customizable ophthalmic lens further comprises another transparent
set of electroactive cells juxtaposed to a surface of the said
lens, said set of cells being suitable for providing another
optical phase-shift distribution function; the transparent set of
electroactive cells and the another transparent set of
electroactive cells are superimposed according to an optical axis
of the lens; the combination of the optical phase-shift
distribution function provided by the transparent set of cells and
the another optical phase-shift distribution function provided by
the another transparent set of cells is adapted to provide to the
wearer a resultant dioptric function; and the projection of the
transparent set of electroactive cells on a surface perpendicular
to the optical axis do not coincide with the projection of the
another transparent set of electroactive cells on said surface
perpendicular to the optical axis, such that boundaries between
some of the cells adjacent to one of the transparent set of cells
cut cells of the another transparent set of cells in the
projection.
15. The active system of vision according to claim 9, wherein: the
transparent sets of electroactive cells is formed by a network of
walls, a set of each point forming a center of one of the cells is
an irregular set of points in the surface of the lens; and a
position and an orientation of each wall are determined such that
the set of cells forms a Voronoi partition of the surface of the
lens.
Description
[0001] This is a U.S. national stage application filed under 35 USC
.sctn.371 of application No. PCT/EP2013/066335, filed on Aug. 8,
2013. This application claims the priority of European application
no. 12305974.3 filed Aug. 3, 2012, the entire content of which is
hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to a method for providing to an eye of
a wearer a customizable ophthalmic lens and to an active system of
vision adapted to carry out the steps of the said method.
[0003] The invention further relates to a computer program product
and a computer readable medium.
BACKGROUND OF THE INVENTION
[0004] The invention relates to the field of active pixelated
transparent optical elements, in particular to carry out an
ophthalmic lens.
[0005] Within the meaning of the invention, an optical element is
transparent when an object that is located on a first side of the
optical element can be viewed without significant loss of contrast
by an observer who is himself across the optical element. The
object and the observer are each located at distance of the optical
element. In other words, an image of the object is formed through
the optical element with no significant loss of quality of visual
perception for the observer, also called "the wearer".
[0006] It is known to carry out an optical element in the form of a
transparent substrate which supports on at least one of its faces,
a set of juxtaposed cells that covers at least in part this face.
Substances having specific optical properties are contained in the
cells, and cooperate to give optical characteristics required for a
particular application to the optical component. For example,
transparent substances having different refraction index can be
divided in cells, so that the resulting component is a draft of
lens adapted to correct visual defects. The optical properties
regarding how the wavefront is modified by the optical element,
also called the "dioptric function", result in the optical
combination of the transparent substrate and of the set of
juxtaposed cells.
[0007] The juxtaposed cells can be in the form of a film which can
be adhered on the optical transparent substrate.
[0008] A final lens can then be obtained by edging the optical
element according to a contour that corresponds to a frame chosen
by the wearer.
[0009] Such a transparent optical element comprising a set of cells
juxtaposed parallel to a surface of the optical element is
generally called a pixelated optical element.
[0010] Such a transparent optical element can also have various
additional optical functions, such as light absorption, polarizing
capability, reinforcement of contrast capability, etc. . . . .
[0011] The dioptric function of the optical element can be
characterized by an optical phase-shift distribution for a given
monochromatic light wave which crosses the optical element.
[0012] In a general way, the transparent optical element has a
surface which extends transversely compared to an optical axis. An
average direction of propagation of the light wave can then be
selected to be superimposed on this axis, and the optical
phase-shift distribution can be given inside the said surface of
the element. In case of pixelated optical elements, optical
phase-shift has discrete values which are carried out in points
which constitute a sampling of the usable surface of the
transparent optical element. In a simplified way, optical
phase-shift could be well established in a zone limited around each
point of sampling, usually called cell. The value of the optical
phase-shift of the element in any point of each cell would be thus
equal to that of the point of sampling which is located in this
cell. In a more realistic way, phase-shift is not constant inside
each cell, but is intermediate between a minimal value and a
maximum value which are fixed by a target function of phase-shift
for this cell. The cells are contiguous in the usable surface of
the optical element, and form a paving of this surface. The actual
dioptric function of the pixelated transparent optical element
results then from the combination of this paving with the values of
optical phase-shift which are carried out in all the cells.
Contiguous pixels can be separated by a wall having a width.
[0013] Moreover, it is well-known that optical phase-shift
.DELTA..phi. for a monochromatic light wave is equal to the product
of the double of number pi by the length of crossing L of each
cell, and by the difference between the value n of refraction index
of the transparent material which fills this cell and the value of
the air index and by the inverse wavelength .lamda.. In other
words: .DELTA..phi.=2.pi.*L*(n-1)/.lamda.. A way of carrying out
the transparent optical element can then consist in varying the
refraction index value of fill material of the cells between
different cells of the element. In this case, all the cells can
have the same depth, which is measured according to the optical
axis of the element.
[0014] For example, for the corrective lens application, it is
advisable for different cells of the optical element to contain
substances of varying refraction index such that the refraction
index is adapted to vary along the surface of the optical element,
according to the estimated ametropy of an eye to be corrected.
[0015] Nevertheless, one can note that optical defects, such as
parasitic images generated in case of periodical repartition of
pixels or blurring in case of non-periodical repartition of pixels
(Voronoi structure detailed below), may appear when wearing
pixelated transparent optical elements.
SUMMARY OF THE INVENTION
[0016] One aim of the present invention is to provide a method for
customizing an active system of vision with enhanced visual comfort
for the wearer and which is suitable to take into account varying
viewing conditions that can be encountered for example in everyday
life.
[0017] Another aim of the present invention is to provide a
structure that allows for the provision in an optical component of
one or more optical functions in a flexible and modular manner.
[0018] To achieve this, one aspect of the invention is directed to
a method for providing to an eye of a wearer a customizable
ophthalmic lens comprising a transparent set of electroactive cells
juxtaposed to a surface of the said lens, said set of cells being
activable and suitable for providing an optical phase-shift
distribution function, the method comprising the steps of: [0019]
providing a reference phase-shift distribution function adapted to
provide to the wearer a given dioptric function DF(.alpha.,
.beta.), said reference phase-shift distribution function being
expressed with respect to a reference point P.sub.R, the reference
phase-shift function having a null gradient at said reference point
P.sub.R; [0020] determining the actual gaze direction
(.alpha..sub.a, .beta.) of the eye of the wearer when wearing the
customizable ophthalmic lens; [0021] choosing a reference gaze
direction (.alpha..sub.R, .beta..sub.R) for positioning said
reference point P.sub.R; [0022] calculating an actual point P.sub.a
and the reference point P.sub.R, said actual point P.sub.a being
the intersection between the actual gaze direction of the eye of
the wearer and the transparent set of electroactive cells and said
reference point P.sub.R being located at the intersection between
the reference gaze direction of the eye of the wearer and the
transparent set of electroactive cells; [0023] calculating a
modified phase-shift distribution function by shifting the
reference phase-shift distribution function according to a vector
{right arrow over (P.sub.RP.sub.a)}; and [0024] activating the
electroactive cells according to the said modified phase-shift
distribution function so as to provide a customized ophthalmic lens
to the eye of the wearer.
[0025] In the frame of the present invention, the wording
"customizable lens" is used to designate a pixelated lens whose
dioptric function can be modified according to the wearer's
needs.
[0026] Individual cells of the pixelated optical element in which
optical phase-shift is likely to take different values have a
minimal size, which is in general determined by the manufacturing
technique of the element. This minimal size spatially limits the
sampling of a function of distribution of the optical phase-shift
which is used as target to fulfill a desired dioptric function. In
other words, the real optical phase-shift distribution function for
the numerical element reproduces only roughly the target
distribution function. The difference between these two functions
of distribution constitutes a defect of the image transportation
which is really produced by the optical element. Such is the case,
in particular, when the target function of distribution is
continuous, or continuous inside portions of the usable surface of
the element.
[0027] For a given width of the walls between the pixels, this
defect increases notably with the increase of the step of the
paving, that is with the increase of the size of the cells. For a
given size of the walls and of the cells and target function of
distribution such as a given target power or astigmatism, the local
difference between target and pixelated functions of distribution
increase with the increase of distance to the optical function
center. Then, the defects induced by pixelation increase when the
direction of gaze of the wearer moves away from this center.
[0028] Thanks to the present invention, it is now possible to
center the optical function of lens compared to the direction of
gaze of the wearer. Centering the optical function of lens compared
to the direction of gaze of the wearer can be done continuously
according to the viewing behavior of the wearer by choosing P.sub.R
to be the centre of the optical function of lens. The defects
induced by pixelation are then significantly minimized and the
quality of vision is significantly improved.
[0029] FIG. 1 schematically represents the quadratic phase-shift
distribution function of a single vision pixelated lens 10. In a
usual case, the quality of an image seen in direction 1, centered
on the optical function of a lens, is correct for a sufficiently
small size of pixels. When the direction of gaze of an eye is
offset according to direction 2, the quality of image is degraded
much.
[0030] Thanks to the invention, the phase-shift distribution
function follows the gaze direction and thus remains always
centered compared to the gaze direction of the eye. The quality of
the image thus is not disturbed any more by the offsetting of the
gaze direction of the eye
[0031] According to an embodiment, the method is implemented by
technical means, as for example by computer means controlling such
a device.
[0032] According to various embodiments that can be combined
according to all the possible combinations: [0033] the transparent
set of electroactive cells is juxtaposed parallel to a surface of
the said lens; [0034] the optical phase-shift distribution function
of the activable cells is substantially constant within each cell;
[0035] the method further comprises the steps of: [0036] providing
a plurality of reference phase-shift distribution functions adapted
to provide to the wearer a plurality of given dioptric functions
DF.sub.n(.alpha., .beta.); and [0037] choosing a reference
phase-shift distribution function among the plurality of reference
phase-shift distribution functions depending on the actual gaze
direction (.alpha..sub.a, .beta..sub.a) of the eye of the wearer
when wearing the customizable ophthalmic lens; [0038] the method
further comprises the steps consisting of: [0039] providing a
plurality of reference phase-shift distribution functions adapted
to provide to the wearer a plurality of given dioptric functions
DF.sub.n(.alpha., .beta.); and [0040] determining an actual viewing
distance of the eye of the wearer; and [0041] choosing a reference
phase-shift distribution function among the plurality of reference
phase-shift distribution functions depending on the actual viewing
distance of the eye of the wearer. [0042] a reference phase-shift
distribution function is chosen among a list of a plurality of
reference phase-shift distribution functions consisting of: at
least a reference phase-shift distribution function adapted to
provide to the wearer a given dioptric function DF.sub.NV(.alpha.,
.beta.) suitable for near vision, at least a reference phase-shift
distribution function adapted to provide to the wearer a given
dioptric function DF.sub.FV(.alpha., .beta.) suitable for far
vision, at least a reference phase-shift distribution function
adapted to provide to the wearer a given dioptric function
DF.sub.IV(.alpha., .beta.) suitable for intermediate vision; [0043]
the method further comprises the steps consisting of: [0044]
providing at least three reference phase-shift distribution
functions adapted to provide to the wearer a given dioptric
functions respectively suitable for near vision DF.sub.NV(.alpha.,
.beta.), suitable for intermediate vision DF.sub.IV(.alpha.,
.beta.) and suitable for far vision DF.sub.FV(.alpha., .beta.);
[0045] determining an actual viewing distance of the eye of the
wearer; and [0046] choosing a reference phase-shift distribution
function among the at least three reference phase-shift
distribution functions depending on the actual viewing distance of
the eye of the wearer such that: [0047] if the actual viewing
distance of the eye of the wearer is in a first range, the
reference phase-shift distribution functions adapted to provide to
the wearer a given dioptric functions respectively suitable for
near vision DF.sub.NV(.alpha., .beta.) is chosen; [0048] if the
actual viewing distance of the eye of the wearer is in a second
range greater than the first range, the reference phase-shift
distribution functions adapted to provide to the wearer a given
dioptric functions respectively suitable for intermediate vision
DF.sub.IV(.alpha., .beta.) is chosen; and [0049] if the actual
viewing distance of the eye of the wearer is in a third range
greater than the second range, the reference phase-shift
distribution functions adapted to provide to the wearer a given
dioptric functions respectively suitable for far vision
DF.sub.FV(.alpha., .beta.) is chosen; [0050] the actual gaze
direction (.alpha..sub.a, .beta..sub.a) of the eye of the wearer
when wearing the customizable ophthalmic lens is determined by
tracking the pupil of the eye of the wearer thanks to an
eye-tracker device.
[0051] Another aspect of the invention is directed to a computer
program product comprising one or more stored sequence of
instructions that is accessible to a processor and which, when
executed by the processor, causes the processor to carry out the
steps of the different embodiments of the preceding method.
[0052] Another aspect of the invention is directed to a computer
readable medium storing one or more sequences of instructions of
the preceding computer program product.
[0053] Another aspect of the invention is directed to an active
system of vision for an eye of a wearer being adapted to be
disposed in front of an eye of the wearer and comprising: [0054] a
customizable ophthalmic lens comprising a transparent set of
electroactive cells juxtaposed to a surface of the said lens, said
set of cells being activable and suitable for providing an optical
phase-shift distribution function, every electroactive cell (24)
having dimensions such that it can be fully comprised in a 70 .mu.m
diameter circle; [0055] a device adapted for determining the actual
gaze direction (.alpha..sub.a, .beta..sub.a) of the eye of the
wearer when wearing the customizable ophthalmic lens; [0056] a
processor operatively connected to the transparent set of
electroactive cells and to the device adapted for determining the
actual gaze direction, wherein the processor is configured to:
[0057] provide a reference phase-shift distribution function
adapted to provide to the wearer a given dioptric function
DF(.alpha., .beta.), said reference phase-shift distribution
function being expressed with respect to a reference point P.sub.R,
the reference phase-shift function having a null gradient at said
reference point P.sub.R; [0058] choose a reference gaze direction
(.alpha..sub.R, .beta..sub.R) for positioning said reference point
P.sub.R; [0059] receive electrical signals dependent on the actual
gaze direction of the eye from said device; [0060] calculate an
actual point P.sub.a and the reference point P.sub.R, said actual
point P.sub.a being the intersection between the actual gaze
direction of the eye of the wearer and the transparent set of
electroactive cells and said reference point P.sub.R being located
at the intersection between the reference gaze direction of the eye
of the wearer and the transparent set of electroactive cells;
[0061] calculate a modified phase-shift distribution function by
shifting the reference phase-shift distribution function according
to a vector {right arrow over (P.sub.RP.sub.a)}; and [0062]
activate the electroactive cells according to the said modified
phase-shift distribution function so as to provide a customized
ophthalmic lens to the eye of the wearer.
[0063] The system is therefore light and very compact because it is
in the form of spectacles. It can be used in everyday life, even
when the user encompasses different successive viewing conditions.
In particular, a person wearing a pair of spectacles of the
invention retains complete freedom of movement with good viewing
ability.
[0064] According to various embodiments that can be combined
according to all the possible combinations: [0065] the active
system of vision further comprises another device adapted for
measuring the actual viewing distance of the eye of the wearer when
wearing the customizable ophthalmic lens; [0066] the another device
adapted for measuring the actual viewing distance of the eye of the
wearer comprises a telemeter adapted to measure the actual viewing
distance of the eye of the wearer when wearing the customizable
ophthalmic lens; [0067] a reference phase-shift distribution
function is chosen among a list of a plurality of reference
phase-shift distribution functions consisting of: at least a
reference phase-shift distribution function adapted to provide to
the wearer a given dioptric function DF.sub.NV(.alpha., .beta.)
suitable for near vision, at least a reference phase-shift
distribution function adapted to provide to the wearer a given
dioptric function DF.sub.FV(.alpha., .beta.) suitable for far
vision, at least a reference phase-shift distribution function
adapted to provide to the wearer a given dioptric function
DF.sub.IV(.alpha., .beta.) suitable for intermediate vision; [0068]
the device adapted for determining the actual gaze direction is
disposed on a face of the transparent set of electroactive cells
facing the eye; [0069] the active system of vision comprises
further features wherein: [0070] the customizable ophthalmic lens
further comprises another transparent set of electroactive cells
juxtaposed to a surface of the said lens, said set of cells being
suitable for providing another optical phase-shift distribution
function, [0071] the transparent set of electroactive cells and the
another transparent set of electroactive cells are superimposed
according to an optical axis of the lens; [0072] the combination of
the optical phase-shift distribution function provided by the
transparent set of cells and the another optical phase-shift
distribution function provided by the another transparent set of
cells is adapted to provide to the wearer a resultant dioptric
function; and [0073] the projection of the transparent set of
electroactive cells on a surface perpendicular to the optical axis
do not coincide with the projection of the another transparent set
of electroactive cells on said surface perpendicular to the optical
axis, such that boundaries between some of the cells adjacent to
one of the transparent set of cells cut cells of the another
transparent set of cells in the said projection; [0074] the active
system of vision comprises further features, wherein: [0075] the
transparent set of electroactive cells is formed by a network of
walls, [0076] a set of each point forming a center of one of the
cells is an irregular set of points in the surface of the lens; and
[0077] a position and an orientation of each wall are determined
such that the set of cells forms a Voronoi partition of the surface
of the lens.
[0078] An active system of vision according to the invention can
advantageously be used for several applications, for example in
aviation field or in adaptive optics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0079] Further features and advantages of the invention will appear
from the following description of embodiments of the invention,
given as non-limiting examples, with reference to the accompanying
drawings listed hereunder:
[0080] FIG. 1 illustrates a phase-shift function of a standard
single vision pixelated ophthalmic lens;
[0081] FIG. 2 is a plan view showing the use of an active vision
according to an embodiment of the invention;
[0082] FIG. 3 is a schematic representation of an active system of
vision for an eye of a wearer according to an embodiment of the
invention;
[0083] FIG. 4 is an exemplary flowchart illustrating steps of the
method according to an embodiment of the invention for providing to
an eye of a wearer a customizable ophthalmic lens;
[0084] FIG. 5 illustrates the schematic principle of the method of
FIG. 4; and
[0085] FIG. 6 is an exemplary flowchart illustrating steps of
another embodiment of the method according to the invention for
providing to an eye of a wearer a customizable ophthalmic lens.
[0086] For clarity, the dimensions of the elements represented in
these figures are not in proportion to the actual dimensions, nor
to the ratios of the actual dimensions. In addition, identical
references in the different figures denote identical elements or
elements with identical functions.
DETAILED DESCRIPTION OF THE DRAWINGS
[0087] With reference to FIG. 2, a pair of spectacles comprises a
frame 3 and two ophthalmic lenses, respectively denoted 1 and 2 for
the right and left lens. The frame 3 holds the lenses 1 and 2 in
relative fixed positions, and allows placing them in front of the
eyes of the wearer in a manner which remains substantially constant
during successive periods of use. The lenses 1 and 2 can be
permanently assembled into the frame 3 using one of the assembly
methods known to opticians.
[0088] The references 100 and 200 denote the wearer's eyes, 100
indicating the right eye and 200 indicating the left eye. For each
of the wearer's eyes 100, 200, the references S, I, P, L and R
denote respectively the sclera, the iris, the pupil, the limbus,
and the center of rotation of the eye. It is known that the iris I
is a circular ring having an inner diameter which is variable and
which determines the size of the pupil P, and a constant outer
diameter. The limbus L is the outside border of the iris L, between
the iris and the sclera S. It is therefore a circle of constant
size which is fixed relative to the corresponding eye when the eye
is turning around its center of rotation R. Visually, the limbus L
is the circular border between the white sclera S and the colored
iris I.
[0089] For each eye 100, 200, the respective axis D1, D2 which
passes through the center of rotation R and the center A of the
corresponding pupil P is the optical axis of that eye. The center A
of the pupil P is also the apex of the crystalline lens. The
optical axis D1, D2, is fixed relative to the respective eye 100,
200, such that it rotates with the limbus L. The optical axes D1
and D2 of the eyes 100 and 200 converge to a common point C, which
is called the point of convergence of the eyes and which is the
location of a virtual object being viewed by the wearer at a given
moment. The average direction D0 of the optical axes D1 and D2 is
the direction of gaze of the wearer at that moment. Usually, the
direction of gaze D0 connects a midpoint of the segment between the
two eyes' centers of rotation R and the point of convergence C. The
observation distance, which is denoted D in FIG. 2, is the distance
of the point of convergence C relative to the centers of rotation
R.
[0090] The invention, which is now described in specific
embodiments as depicted in FIG. 2, is based on the determination of
the direction of gaze D0 relatively to the face of the wearer. To
achieve this, a method for determining the direction of gaze of a
wearer is carried out. For example, WO 2010/130932 A1 proposes such
method for determining the direction of gaze of a wearer.
[0091] In WO 2010/130932 A1, the direction of gaze D0 is determined
by detecting the rotational position of each eye 100, 200 relative
to the corresponding lens 1, 2. Thus each lens 1, 2 according to WO
2010/130932 A1 allows determining the angular position of the
optical axis D1, D2 of the corresponding eye 100, 200. The
direction of gaze D0 of the wearer is then deduced from the
respective positions of the two optical axes D1 and D2.
[0092] To define the position of the optical axis of each eye, two
angles are used, .alpha. and .beta., respectively called the
elevation and eccentricity. The elevation .alpha. is usually
identical for both eyes 100 and 200, and is the angle between each
optical axis D1 or D2 and a reference plane which is horizontal
when the wearer's head is vertical. The elevation value for the
direction of gaze D0 is then also equal to this common value.
[0093] The eccentricity .beta. of the optical axis D1 or D2 of each
eye is the angle between this axis and a median plane of the face,
which is vertical when the wearer's head is vertical. The
eccentricity .beta. can be considered as positive in the direction
of the wearer's nose for each eye, and generally has absolute
values which are distinct for the two eyes at the same moment. The
difference between these two absolute values determines the
convergence of the eyes, meaning the observation distance D. The
azimuth value for the direction of gaze D0 is equal to half the
difference of the respective eccentricity values for the two eyes,
using the orientation convention of eccentricity angles just
indicated.
[0094] In practice, the elevation and eccentricity of the optical
axis D1, D2 of each eye 100, 200 may be determined based on the
position of the limbus L of that eye.
[0095] A given gaze direction corresponds to a couple (.alpha.,
.beta.).
[0096] It is well-known by the man skilled in the art to define
dioptric function DF(.alpha., .beta.) adapted to correct visual
defects of the wearer in this reference system of coordinates
(.alpha., .beta.), i.e. according to each gaze direction of the
wearer.
[0097] Now, an active vision system of vision for an eye of a
wearer according to the invention will be described in details with
reference to FIG. 3.
[0098] The active system of vision 20 for an eye 100, 200 of a
wearer comprises a customizable ophthalmic lens 22. The active
system of vision is adapted to be disposed in front of an eye of
the wearer.
[0099] The customizable ophthalmic lens comprises a transparent set
24 of electroactive cells juxtaposed parallel to a surface of the
said lens. Said set of cells is suitable for providing an optical
phase-shift distribution function with a substantially constant
value within each cell.
[0100] Preferably, each cell 26 is filled with an active
electro-material such that the refraction index can vary in each
pixel independently from each other under the action of an electric
field induced by individual electrodes 28.
[0101] Of course, the active system of vision comprises a device 30
adapted to provide the adapted electric field.
[0102] FIG. 3 illustrates a pixelated lens having a plane surface.
Nevertheless the surface can be unspecified. Indeed, it is
well-known of the man skilled in the art methods to manufacture
pixelated ophthalmic lenses having unspecified surfaces.
[0103] The set of cells is suitable for providing an optical
phase-shift distribution function with a constant value within each
cell.
[0104] Advantageously the set of cells covers the whole surface of
the lens. This enables to provide to the wearer a good vision in a
broad field of view.
[0105] Furthermore, the active system of vision for an eye of a
wearer comprises a device 32 adapted for determining the actual
gaze direction (.alpha..sub.a, .beta..sub.a) of the eye of the
wearer when wearing the customizable ophthalmic lens.
[0106] For example, said device is adapted to characterize the
direction of gaze of a wearer according to WO 2010/130932 A1.
[0107] The device can be disposed on a face of the transparent set
of electroactive cells facing the eye.
[0108] For example, the device 32 comprises an eye-tracker system
adapted to determine the actual gaze direction (.alpha..sub.a,
.beta..sub.a) of the eye of the wearer when wearing the
customizable ophthalmic lens.
[0109] Moreover, the active system of vision further comprises a
control unit 34 comprising a processor 36 operatively connected to
the transparent set of electroactive cells and to the device. Thus,
the processor 36 is configured to receive electrical signals
dependent on the actual gaze direction of the eye from said device
32.
[0110] Furthermore, the processor is configured to provide a
reference phase-shift distribution function adapted to provide to
the wearer a given dioptric function DF(.alpha., .beta.) and to
choose a reference gaze direction (.alpha..sub.R,
.beta..sub.R).
[0111] To achieve this, the control unit 34 comprises a memory 38
wherein a reference control signal is stored; the reference control
signal is adapted to activate each electroactive cells to provide
the reference phase-shift distribution function.
[0112] Activating the transparent set of electroactive cells
requires implicitly the use of a pixelated phase-shift distribution
function for driving the individual cells. Pixelisation operations
can either be carried out beforehand, or either can be carried out
at each change of the gaze direction. First case is advantageous in
terms of calculation load; second case is advantageous in terms of
precision for positioning the modified phase-shift distribution
function.
[0113] More precisely, in the first case, when the set of cells
comprises constant shape size cells with regular and periodic
spatial repartition, the reference control signal comprises the
result of pixelating operations carried out once on said reference
phase-shift distribution function according to the set of
electroactive cells size, shape and location. This reference
control signal is then shifted depending on the gaze direction.
[0114] Advantageously, the reference control signal can be uploaded
within the active system of vision through a dedicated connector or
a without contact connection providing an access to the control
unit 34 and the memory 38. This allows cheap update of the
reference control signal in relation with a change in the need of
ophthalmic correction of the wearer.
[0115] The reference gaze direction (.alpha..sub.R, .beta..sub.R)
associated to the reference phase-shift distribution function is
stored in the memory too. In operation, the processor reads, in the
memory, the reference gaze direction (.alpha..sub.R, .beta..sub.R)
associated to the reference phase-shift distribution function.
[0116] Then, the processor 36 is configured to calculate an actual
point P.sub.a and a reference point P.sub.R. Said actual point
P.sub.a is defined by the intersection between the actual gaze
direction of the eye of the wearer and the transparent set of
electroactive cells, and said reference point P.sub.R is defined by
the intersection between the reference gaze direction of the eye of
the wearer and the transparent set of electroactive cells.
[0117] Alternatively reference point P.sub.R is stored and the
reference gaze direction (.alpha..sub.R, .beta..sub.R) is
calculated.
[0118] Moreover, the processor is configured to calculate a
modified phase-shift distribution function by shifting the
reference phase-shift distribution function according to a vector
{right arrow over (P.sub.RP.sub.a)} and to activate the
electroactive cells according to the said modified phase-shift
distribution function so as to provide a customized ophthalmic lens
to the eye of the wearer. Moreover the processor is advantageously
further configured to calculate a modified phase-shift distribution
function by rotating the reference phase-shift distribution
function according to predefined angle values so as to provide a
customized ophthalmic lens to the eye of the wearer taking into
account a variation of astigmatism axis direction of this eye in
function of the gaze direction.
[0119] The device is adapted to carry out the steps of the method
400 according to the invention which will reference to FIG. 4.
[0120] The method comprises a step 402 for providing a reference
phase-shift distribution function adapted to provide to the wearer
a given dioptric function DF(.alpha., .beta.).
[0121] This dioptric function was pre-calculated in order to
correct visual defects of the wearer. A reference phase-shift
distribution function has then be calculated to provide to the
wearer a given dioptric function DF(.alpha., .beta.) in association
with a reference point P.sub.R. For example, the dioptric function
DF(.alpha., .beta.) comprises a rotational symmetry and P.sub.R is
located at the symmetry center of the dioptric function DF(.alpha.,
.beta.).
[0122] Each electroactive cell is then activated according to the
said calculated phase-shift distribution function.
[0123] Then, a step 404 for determining the actual gaze direction
(.alpha..sub.a, .beta..sub.a) of the eye of the wearer when wearing
the customizable ophthalmic lens is carried on. For example and
preferably, the actual gaze direction (.alpha..sub.a, .beta..sub.a)
of the eye of the wearer is determined by tracking the pupil of the
eye of the wearer thanks to an eye-tracker device. As indicated
before, a method according to WO 2010/130932 A1 for determining the
actual gaze direction of the wearer is for example carried out.
[0124] A reference gaze direction (.alpha..sub.R, .beta..sub.R) is
chosen during a step 406.
[0125] For example, the reference gaze direction (.alpha..sub.R,
.beta..sub.R) is a primary gaze direction.
[0126] Furthermore, the method comprises a step 408 for calculating
an actual point P.sub.a and a reference point P.sub.R. The actual
point P.sub.a is the intersection between the previously detected
actual gaze direction of the eye of the wearer and the transparent
set of electroactive cells. The reference point P.sub.R is the
intersection between the reference gaze direction of the eye of the
wearer and the transparent set of electroactive cells.
[0127] Then, in step 410, a modified phase-shift distribution
function is calculated by shifting the reference phase-shift
distribution function according to a vector {right arrow over
(P.sub.RP.sub.a)}.
[0128] Moreover, the method comprises a step 412 for activating the
electroactive cells according to the said modified phase-shift
distribution function so as to provide a customized ophthalmic lens
to the eye of the wearer.
[0129] FIG. 5 illustrates the result obtained by this method. The
same function of phase of the pixelated lens of FIG. 1 is
represented. Thus, when the eye of the wearer looks in direction 1,
the quality of the image seen is correct since the dioptric
function of lens is centered on a reference gaze direction. And
when the eye of the wearer looks in a direction 2 for example
passing by the periphery of lens, the same dioptric function in
terms of power and astigmatism which was previously calculated to
correct visual defects of the wearer is applied.
Example
[0130] Let us consider a pixelated lens, illuminated by a 550 nm
wavelength monochromatic light, whose phase-shift distribution
function is quadratic, corresponding to a dioptric power P. Every
pixel of this lens has a square shape, and its pitch is denoted p.
The size of the walls between pixels is considered zero. The pupil
of this lens is supposed to be a square A.times.A, with A=6 mm.
[0131] In Table 1 calculated from publication <<Shape of
diffraction orders of centered and decentered pixelated lenses.
Appl. Opt., 49(6):1054-1064, 2010 from Marius Peloux, Pierre
Chavel, Francois Goudail, and Jean Taboury>>, one shows the
part of useful light .eta.(0,0), corresponding to (0,0) diffraction
order effectiveness, the remaining light being diffracted in other
diffraction orders corresponding to parasitic images.
[0132] With P=2.delta., unless the pixel pitch p is very small, 5
.mu.m for instance, one sees that .eta.(0,0) displays non
acceptable values in ophthalmic optics.
[0133] For lower values of P, say P=0.5.delta., one can accept a
pixel pitch up to 50 .mu.m. Thus, the present invention deals with
set of electroactive cells (pixels) whose pitch is smaller than 50
.mu.m typically, ie. pixels having dimensions such that it can be
fully comprised in a .apprxeq.70 .mu.m diameter circle.
TABLE-US-00001 TABLE 1 .eta.(0, 0), A = 6 mm, P = 2.delta., .lamda.
= 550 nm P (.mu.m) 100 50 5 .eta.(0, 0) 0.19 0.57 1-6.5
10.sup.-3
[0134] The conditions leading to the results of Table 1 were
obtained in a case were the lens pupil is centered with regard to
the quadratic function of the lens. In order to describe the case
where the pupil is decentered with regard to the quadratic function
of the lens, which corresponds, in usual case, to a situation where
the wearer's gaze direction is translated from the center of a
pixelated lens, tests were carried out in order to quantify the
interest of the invention for a lens having power equal to 2.delta.
(diopter) and having 5 .mu.m-square pixels, whose size of the walls
between contiguous cells is considered as equal to zero.
[0135] For an horizontal translation of 10 mm of the gaze direction
of the eye of a wearer compared to a fixed pupil having a 6 mm
diameter, for simplicity's sake assumed to be stuck onto a plane
lens and considering a quadratic phase-shift distribution function
which corresponds if the wearer looks at the edge of its lens, the
quantity of useful light for the wearer is equal to 0.89,
corresponding to (0,0) diffraction order effectiveness. This is
unacceptable in ophthalmic optics.
[0136] With the present invention, when the optical function of
lens follows the gaze of the wearer, the situation is always
brought back in the case of a null translation, so the quantity of
useful light for the wearer is then equal to 0.994=1-1.65
10.sup.-3, showing the interest of the active system of vision of
the invention.
[0137] With a 5.delta. power, this quantity of useful light is
higher than .gtoreq.0.96. Consequently, it is possible to have
customizable lenses according to the invention having high
power.
[0138] The same reasoning applies to the cases of astigmatism
phase-shift distribution functions, for which the centering of the
distribution function with regard to the gaze direction is also of
great interest.
[0139] In an advantageous embodiment of the present invention, one
considers a phase-shift distribution function adapted for reducing
the diffraction effects caused by the pixelisation, in the vicinity
of this reference point P.sub.R. Let's consider a phase-shift
distribution function having a null gradient at a reference point
P.sub.R. This condition is met if one considers for instance
defocus-only or astigmatism-only functions centered on the
reference point P.sub.R.
[0140] When the wearer gaze direction changes, the optical
function, which is a pixelated version of the considered refractive
function, follows so as to always keep a null gradient of the
refractive phase-shift distribution function at the intersection
P.sub.a of the gaze direction and the pixelated lens.
[0141] Keeping a null gradient in the refractive phase-shift
distribution function at P.sub.a has a noticeable effect. Indeed,
in a first order paraxial approximation, it also implies an absence
of prismatic deviation at the center of the wearer field of view
whatever the gaze direction. Then, in addition to the fact that the
parasitic diffraction effects caused by pixelation are minimized,
thanks to the centering of the phase-shift distribution function,
the wearer is never affected by prismatic deviations leading to
magnifying changes as it is the case in common unifocal lenses.
[0142] According to a second embodiment of the method, said method
further comprising a step 420 for providing a plurality of
reference phase-shift distribution functions adapted to provide to
the wearer a plurality of given dioptric functions
DF.sub.n(.alpha., .beta.).
[0143] For example, each given dioptric functions DF.sub.n(.alpha.,
.beta.) is adapted to provide a different power and/or astigmatism
suitable for a specific activity (reading, a do-it-yourself
activity . . . ).
[0144] A plurality of control signals were calculated beforehand
and recorded in a memory. Each control signal is adapted to
activate the whole electroactive cells in order to provide to the
wearer a given dioptric functions DF.sub.n(.alpha., .beta.) among
the plurality of given dioptric functions DF.sub.n(.alpha.,
.beta.).
[0145] According to a first subembodiment, this step 420 is then
followed by a step 422 for choosing a reference phase-shift
distribution function among the plurality of reference phase-shift
distribution functions. This choice is done as a function of the
actual gaze direction (.alpha..sub.a, .beta..sub.a) of the eye of
the wearer when wearing the customizable ophthalmic lens.
[0146] For example, a reference phase-shift distribution function
is chosen among a list of a plurality of reference phase-shift
distribution functions consisting of: [0147] at least a reference
phase-shift distribution function adapted to provide to the wearer
a given dioptric function DF.sub.NV(.alpha., .beta.) suitable for
near vision, [0148] at least a reference phase-shift distribution
function adapted to provide to the wearer a given dioptric function
DF.sub.FV(.alpha., .beta.) suitable for far vision, and [0149] at
least a reference phase-shift distribution function adapted to
provide to the wearer a given dioptric function DF.sub.IV(.alpha.,
.beta.) suitable for intermediate vision.
[0150] In another example the reference phase-shift distribution
functions have various astigmatism axis directions depending on the
gaze direction. For example the astigmatism value and axis
direction is different for near vision, far vision and intermediate
vision.
[0151] According to a second subembodiment, a step 424 for
determining an actual viewing distance of the eye of the wearer is
carried out after the step 420 and before choosing a reference
phase-shift distribution function among the plurality of reference
phase-shift distribution functions depending on the actual viewing
distance of the eye of the wearer in 426.
[0152] Of course, this second subembodiment is compatible with the
first subembodiment. Thus, the reference phase-shift distribution
function can be chosen among the plurality of reference phase-shift
distribution functions as a function of both the actual gaze
direction (.alpha..sub.a, .beta..sub.a) and/or the actual viewing
distance of the eye of the wearer.
[0153] The definition of actual viewing distance has no significant
influence on the way the reference phase-shift distribution
function can be chosen. The actual viewing distance can be
evaluated as the distance separating an object and the front face
of the lens or the object and the pupil of the eye of the wearer or
even the object and the center of rotation of the eye of the
wearer. The choice of a definition of actual viewing distance among
the previous one is mainly linked with the device adapted for
measuring the actual viewing distance as discussed below. For
example, at least three reference phase-shift distribution
functions adapted to provide to the wearer a given dioptric
functions respectively suitable for near vision DF.sub.NV(.alpha.,
.beta.), suitable for intermediate vision DF.sub.IV(.alpha.,
.beta.) and suitable for far vision DF.sub.FV(.alpha., .beta.) can
be provided.
[0154] Then, an actual viewing distance of the eye of the wearer is
determined.
[0155] The reference phase-shift distribution function is chosen
among the at least three reference phase-shift distribution
functions depending on the actual viewing distance of the eye of
the wearer: [0156] if the actual viewing distance of the eye of the
wearer is in a first range, for example between 0.20 and 0.45 m,
the reference phase-shift distribution functions adapted to provide
to the wearer a given dioptric functions respectively suitable for
near vision DF.sub.NV(.alpha., .beta.) is chosen; [0157] if the
actual viewing distance of the eye of the wearer is in a second
range greater than the first range, for example between 0.45 and
1.50 m, the reference phase-shift distribution functions adapted to
provide to the wearer a given dioptric functions respectively
suitable for intermediate vision DF.sub.IV(.alpha., .beta.) is
chosen; and [0158] if the actual viewing distance of the eye of the
wearer is in a third range greater than the second range, for
example superior then 1.50 m, the reference phase-shift
distribution functions adapted to provide to the wearer a given
dioptric functions respectively suitable for far vision
DF.sub.FV(.alpha., .beta.) is chosen.
[0159] Here "a second range greater than the first range" must be
understood as each value of the second range is greater than each
value of the first range. Of course, this definition applies
mutatis mutandis to the third range which is greater than the
second range.
[0160] With such a method whatever the embodiments, it is possible
to build ophthalmic lenses whose dioptric power can vary according
to the wearer's needs, these lenses thus playing the part of a
flexible crystalline lens. More generally, an advantage of the
pixelation consists of what any phase-shift function can be coded
in lens, constantly and at any place of lens and able to vary with
time.
[0161] For presbyopic wearers, the value of the power correction is
different for far vision and for near vision, due to difficulty in
accommodation for near vision. The prescription thus comprises a
power value for far vision and a power addition representative of
the power increment between far vision and near vision. The power
addition is termed the prescribed addition. Ophthalmic lenses which
compensate for presbyopia are multifocal lenses, the most suitable
being progressive multifocal lenses. An active system of vision
according to the invention having a plurality of given dioptric
functions ensures the same optical function as a multifocal lenses
without the disadvantages of having astigmatism defects located in
peripheral zone of the lens. Moreover, this allows broad field of
view whatever the gaze direction. Thus, such active system of
vision can be used to compensate for presbyopia and allows the
spectacle wearer to see objects over a wide range of distances,
without having to remove his or her glasses.
[0162] In order to achieve the second subembodiment of the method,
the active system of vision according to a second embodiment,
further comprises another device adapted for measuring the actual
viewing distance of the eye of the wearer when wearing the
customizable ophthalmic lens.
[0163] For example, said another device synthesizes measures of
actual gaze direction of each of the two eyes of the wearer and
determines from those two directions a convergence distance used
for evaluating the actual viewing distance of the eyes of the
wearer when wearing the customizable ophthalmic lens.
[0164] In another example, said another device comprises a
telemeter adapted to measure the actual viewing distance of the eye
of the wearer when wearing the customizable ophthalmic lens.
[0165] Moreover, the other device can be disposed on a face of the
transparent set of electroactive cells facing the eye.
[0166] The applicant has also proposed, for example in FR1152134
and in WO 2011/144852 A1, transparent optical components having a
cellular structure allowing respectively a virtual pixel size
reduction (pixel superimposition) and an advantageous repartition
of the defects induced by pixelation (Voronoi structures) to
overcome the technological limit imposing a minimal size of the
cells and so allowing to minimize the embarrassment perceived by a
wearer.
[0167] As explained above, defects induced by pixelated set of
cells depend on the size of the cells.
[0168] To significantly reduce these disadvantages, FR1152134
proposes a transparent optical element which comprises a plurality
of layers superimposed according to an optical axis of the element.
Each layer extends perpendicular to the optical axis, and consists
of a paving of contiguous cells. For each layer, an optical
phase-shift distribution function has a constant value inside each
cell of this layer as discussed above. The dioptric function of the
element results then from a combination of the respective optical
phase-shift distribution functions of the layers.
[0169] The said other set of cells is suitable for providing
another optical phase-shift distribution function with a constant
value within each cell. The combination of the optical phase-shift
distribution function provided by the transparent set of cells and
the other optical phase-shift distribution function provided by the
another transparent set of cells is adapted to provide to the
wearer a resultant dioptric function.
[0170] The projection of the transparent set of electro-active
cells on a surface perpendicular to the optical axis do not
coincide with the projection of the another transparent set of
electro-active cells on said surface perpendicular to the optical
axis, such that boundaries between some of the cells adjacent to
one of the transparent set of cells cut cells of the another
transparent set of cells in the said projection.
[0171] Thus, in the surface of projection, the cells of one of the
layers themselves are divided by intercellular limits of the other
layer. The superimposition of the two layers then appears divided
into useful cells which have dimensions lower or equal to those of
the cells of each layer. In other words, the superimposition of
layers enables to reduce an apparent size of useful cell to produce
a given dioptric function as a result of an optimization process.
For this reason, the optical phase-shift distribution function of
the element of the invention can present a variation which is tiny
room compared to a target distribution function, in particular
compared to a target distribution function which is continuous or
continuous by portions. This causes to decrease the intensity of
the parasitic light which is diffracted and to leave again
angularly best. This one is then less perceptible.
[0172] The invention described in FR1152134 is compatible with the
present invention.
[0173] So, according to a third embodiment of the active system of
vision, the customizable ophthalmic lens further comprises another
transparent set of electroactive cells juxtaposed parallel to the
surface of the said lens. The transparent set of electroactive
cells and the other transparent set of electroactive cells are
superimposed according to an optical axis of the lens.
[0174] WO 2011/144852 A1 proposes a transparent optical component
having a cellular structure wherein disorder in the form and the
distribution of the pixels of a pixelated lens is induced. This
disorder allows transforming the parasitic orders of diffraction
(corresponding to parasitic images) associated with a lens with
periodic repartition of its pixels into a diffuse fog less awkward
for the wearer.
[0175] The invention described in WO 2011/144852 A1 is compatible
with the present invention.
[0176] So, according to a fourth embodiment, compatible with
previous ones, of the active system of vision, wherein the
transparent set of electroactive cells is formed by a network of
walls. A position and an orientation of each wall are determined
such that the set of cells forms an optimized Voronoi partition of
the surface of the lens.
[0177] Furthermore, the invention also relates to a computer
program product comprising one or more stored sequence of
instructions that is accessible to a processor and which, when
executed by the processor, causes the processor to carry out the
steps of the different embodiments of the preceding methods.
[0178] The invention also proposes a computer readable medium
carrying out one or more sequences of instructions of the preceding
computer program product.
[0179] Unless specifically stated otherwise, as apparent from the
following discussions, it is appreciated that throughout the
specification discussions utilizing terms such as "evaluating",
"computing", "calculating" "generating", or the like, refer to the
action and/or processes of a computer or computing system, or
similar electronic computing device, that manipulate and/or
transform data represented as physical, such as electronic,
quantities within the computing system's registers and/or memories
into other data similarly represented as physical quantities within
the computing system's memories, registers or other such
information storage, transmission or display devices.
[0180] Embodiments of the present invention may include apparatuses
for performing the operations herein. This apparatus may be
specially constructed for the desired purposes, or it may comprise
a general purpose computer or Digital Signal Processor ("DSP")
selectively activated or reconfigured by a computer program stored
in the computer. Such a computer program may be stored in a
computer readable storage medium, such as, but is not limited to,
any type of disk including floppy disks, optical disks, CD-ROMs,
magnetic-optical disks, read-only memories (ROMs), random access
memories (RAMs) electrically programmable read-only memories
(EPROMs), electrically erasable and programmable read only memories
(EEPROMs), magnetic or optical cards, or any other type of media
suitable for storing electronic instructions, and capable of being
coupled to a computer system bus.
[0181] The processes and displays presented herein are not
inherently related to any particular computer or other apparatus.
Various general purpose systems may be used with programs in
accordance with the teachings herein, or it may prove convenient to
construct a more specialized apparatus to perform the desired
method. The desired structure for a variety of these systems will
appear from the description below. In addition, embodiments of the
present invention are not described with reference to any
particular programming language. It will be appreciated that a
variety of programming languages may be used to implement the
teachings of the inventions as described herein.
[0182] It should be noted more generally that the invention is not
limited to the described and represented examples.
[0183] In particular, in the described examples the lens is single
vision or multifocal. Nevertheless, the invention applies in the
same manner for pixelated lenses associated with the correction of
defects of astigmatism or other visual defects.
* * * * *