Patent Application
20230404387
The invention relates to an optometry device for testing an individual's eye, to a set of pictures for said device and to a display unit of such set of pictures.
Document EP 3 298 952 describes such a device comprising:
In this device, the contrast of the visual test image seen by the individual through the refraction test unit may be low due to the superimposition of the scene image with the visual test image.
Hence, this device with said display unit may not exhibit the same reliability and the same precision as a standard device for measuring the subjective refraction of an individual.
Therefore one object of the invention is to provide an optometry device for measuring the subjective refraction of an individual that delivers measurement results which can be compared to those of a standard device.
The above objects are achieved according to the invention by providing an optometry device as defined above, wherein said at least one control unit is configured to define in the scene picture at least one scene zone implying transparency for the corresponding virtual scene image and in the superimposition area between the visual test image and the scene image, allowing the individual's eye to observe the functional zone of the visual test image without contrast decrease, at the visual test distance.
It is thus possible with the invention to enhance the contrast of the visual test image perceived by the individual looking both at the visual test image and at the scene image at the same time through the refraction test unit.
Other advantageous and non-limiting features of the optometry device according to the invention include:
The invention also relates to a set of pictures comprising a visual test picture and a scene picture, said set of pictures being useful for an optometry device having a vision correction optical system for providing different vision correction power values for testing an individual's eye, the optometry device including a projection optical system adapted to produce from corresponding scene picture and corresponding visual test picture including a functional zone, respectively:
Other advantageous and non-limiting features of the set of pictures according to the invention include:
The invention further concerns a computer-program product for a data processing device, the computer program product comprising a set of instructions which, when loaded into the data processing device, causes the data processing device to perform the display of the set of images as defined above.
Finally, the invention relates to a display unit comprising:
The following description, enriched with joint drawings that should be taken as non limitative examples, will help understand the invention and figure out how it can be realized.
On joint drawings:
In the following description, identical or corresponding elements of each embodiment will be referred to with the same sign of reference and will not be described in details each time.
The optical paths of light are represented in dashed lines, the sense of propagation of the light being indicated by arrowheads.
The visual sensation of a color stimulus is generally considered as being separated into two supposedly independent parts, luminance and chromaticity.
Luminance is the power of visible light passing or being emitted at a surface element in a given direction, per unit area and per unit of solid angle.
Mobility of an optical component is indicated by double arrows placed beside.
We represent on
The optometry device 100 comprises:
In the present embodiment represented on the
The casing 2 encloses here the display unit 20 whereas the refraction test unit 10 of the optometry device 100 is here mounted on the casing 2, at the exterior of the latter.
The visual test image and the scene image are visible by the individual through the vision correction optical system 13 of the refraction test unit 10 when the refraction heads adopt their closed configuration (we will explain later how those images are formed) or without this vision correction optical system 13 when the refraction heads adopt their opened configuration. In practice, the visual test image and the scene image are visible through an exit aperture 10A of the refraction test unit 10 of the optometry device 100.
The refraction test unit 10 is interposed between the display unit 20 and the individual's eye 1 in the closed configuration of the refraction heads. It is movable (see double-heads arrow in
The refraction test unit 10 may be of any kind known to the man skilled in the art. Such refraction test unit 10 is usually called “phoropter”. A phoropter is adapted to provide a variable optical correction for the individual's eye 1 looking through it.
In particular, it may comprise a classical optical system 13 (see
The lenses with different powers are interchanged through a manual or preferably through a motorized command (not represented). These different powers are vision correction powers for the eye 1 of the individual placed nearby.
The refraction test unit 10 preferably comprises a vision correction optical system with one or a plurality of lenses with adjustable power, such as liquid lenses.
The refraction test unit 10 is for instance a visual compensation system as described in document WO 2015/155458.
The refraction test unit 10 for example includes a lens having a variable spherical power.
Said variable spherical power lens has for instance a deformable surface. The shape of this surface (in particular the radius of curvature of this surface, and hence the spherical power provided by the lens) can be controlled by moving a mechanical part (such as a ring), which mechanical part may be driven by a motor of the refraction test unit 10.
The refraction test unit may also include a pair of independently rotatable lenses each having a cylindrical power. These lenses may each be rotated by action of other motors of the refraction test unit 10.
The various motors of the refraction test unit 10 are driven by a control unit 14 (e.g. see
The various elements of the refraction test unit 10 (such as the variable spherical power lens, the cylindrical lenses, the motors and the control unit) are enclosed in a housing 12 shown on
In the present embodiment, the optometry device 100 includes two visual compensation systems as mentioned above (vision correction optical system), each such system being situated in front of one of the individual's eyes. The adjustable powers of these visual compensation systems are vision correction powers for the eye 1 of the individual placed nearby.
The exit aperture 10A of the optometry device 100 corresponds to opening of the refraction test unit 10 where the individual may position his eye 1 to look through the optical system 13 of the refraction test unit 10, namely the phoropter or visual compensation system (vision correction optical system). This exit aperture is centered on the optical axis of the lens or lenses of the refraction test unit.
However, the exit aperture is usually off-centered relative to an optical axis of the optical elements of the display unit, as will be described in more details later.
The refraction test unit 10 optionally comprises one or more elements designed to receive the head 13 (see
Alternatively or in addition, the refraction test unit could comprise an element to receive the chin of the individual.
Such refraction test unit 10 is well-known in the art of optometry and will not be described in more details here.
In the closed configuration of the refraction heads, the light beam 23 (see
In the invention, and as represented on
In the example of
Hence, the projection optical system can produce simultaneously two kinds of images.
First, the first projection sub-system 20A (i.e. “acuity module”) forms (i.e. projects) a visual test image OPT (see
Optically, the visual test image OPT is visible by the individual through the vision correction optical system 13 at a visual test distance (hereinafter noted D1) from the individual's eye 1.
In the example of
Second, the second projection sub-system 20B (i.e. “scene module”) forms (i.e. projects) a scene image SCN (see
Like the respective optical paths described above, the scene image SCN is superimposed with the visual test image OPT and is visible by the individual through the vision correction optical system 13 at a background distance of projection (hereinafter noted D2) from the individual's eye 1. In practice, this background distance D2 of projection is greater than or equal to the visual test distance D1 of projection.
Again, in the example of
The visual test screen 21 and the scene screen 22 are any kind of flat panel displays such as a TFT-LCD screen or an OLED/QLED/μLED screen.
We will now describe in more details the example of acuity module 20A with reference to
As shown on these figures, the acuity module 20A comprises at least one optical element 30 having an optical power (in diopters).
This optical element 30 is movable between:
The visual optical path is the path that a light beam emitted by the visual test screen 21 at a center of the picture displayed by this screen 21 takes in traversing the display unit 20 to reach the exit aperture 10A of the refraction test unit 10.
Hence, the visual test image OPT comprises:
By “projected”, it is meant that an image of the visual test picture is optically formed by the optical element, such as e.g. the lens 31. This optical image of the visual test picture formed by the lens (and reflected or not) is a virtual image of the visual test picture displayed on the first screen 21.
When the optical element 30 is in its retracted position (e.g. see
When the optical element 30 is in its active position (e.g. see
The distance D1 of projection between the visual test image OPT and the exit aperture 10A of the refraction test unit 10 is then the geometrical/physical distance between the exit aperture 10A (which is generally planar or substantially planar) and the optical position of the (virtual) visual test image (including the optical folding paths defined by the reflecting surface if present).
The optical element 30 may comprise for example an optical lens 31, as in the example described here (see
In the case where the optical element 30 comprises an optical lens 31, the image of the visual test picture is the image of the visual test picture seen through the lens 31.
In the present optometry device 100, the distance D1 between the visual test image OPT and the exit aperture 10A can vary at least between a distance of far vision (FV) and a different distance of near (NV) or intermediate vision (IV).
A distance of far vision is typically comprised between infinity and centimeters (cm), preferably above 4 to 6 meters. A distance of intermediate vision is typically comprised between 65-70 and 40 cm. A distance of near vision is typically below 40 cm, preferably comprised between 40 and 33 cm.
Preferably, the relative positions of the visual test screen 21, the optical element 30 and the exit aperture 10A are adapted to be varied in order for this first distance D1 of projection between the visual test image OPT produced and the exit aperture 10A to be continuously modified inside one or several ranges of optical distances (first distances D1) between infinity and a near vision (NV) distance.
Preferably, the first distance D1 between the visual test image OPT produced and the exit aperture 10A may take any value comprised between infinity and a near vision distance.
The visual test picture displayed by the visual test screen 21 is for example an optotype. Other types of picture adapted to test the vision of the individual may be used, as known by the man skilled in the art. The acuity module 20A is thus designed to produce visual test images (representing an object, such as an optotype) for the individual's eye 1.
The optical element 30 comprises here an optical lens 31. Lens 31 is here an achromatic lens, having an effective focal length between 70 cm and 100 cm (1 meter), preferably of about 80 cm, for instance. It comprises for example an achromatic doublet. It may also be for example a simple lens such as e.g. a plano-convex lens or a more complex lens such as an aspherical lens. In the case where a simple lens is used, this simple lens has preferably an effective focal length of more than 80 cm to limit chromatic aberrations.
The effective focal length (usually referred to as “EFL”) of the lens 31 corresponds to the optical power of the lens itself. It is measured between a focal plane of the lens and a theoretical plane placed inside the lens (known usually as “principal image plane”). As it is not easy to position optical elements relative to the lens using the effective focal length, the position of the theoretical plane being difficult to precisely determine, a back focal length may be used.
The back focal length (usually referred to as “BFL”) of the lens 31 is measured between the last diopter summit (i.e. vertex) of the lens and the focal plane of the lens along an optical axis L (see
As explained later, the optical axis L is here folded by the use of reflective surfaces such as mirrors (see
Alternatively, the use of lenses with a small effective focal length, for example 20 cm, is possible with a smaller screen such as a miniature screen of about 1 inch (=2.54 cm) with high resolution HD, full HD or even 4K/8K. This could be used for obtaining a smaller device.
Preferably, the optical element 30 and the visual test screen 21 are arranged relative to each other so that there is at least one relative position of the optical lens 31 and the screen 21 for which the screen 21 is placed at a distance from the optical lens 31 equal to the back focal length of said lens 31.
Therefore, in a far vision configuration, while the lens 31 is placed on the visual test optical path of the light, the relative position of said screen 21 and said lens 31 may be adjusted for the screen 21 to be located at a back focal length from said lens 31.
This way, the visual test image generated by the display module 20 may be placed at infinity relative to the exit aperture 10A, and therefore, the eyes of the individual. The distance between the visual test image produced and the exit aperture is then set as infinite.
As shown in
In the case of the optical element 30 being a lens 31, the light beam goes through the lens 31 when it is in the active position and does not go through the optical lens 31 when it is in the retracted position.
Thanks to this, the visual test projection sub-system 20A (acuity module) is adapted to produce the image of the visual test picture at a variable distance for the individual's eye 1.
In practice, here, the optical element 30 comprises the lens 31. It is fixed on a support 32 that is pivotally mounted on part of the casing 2 of the optometry device 100.
In a first angular position of the support 32 of the lens 31, shown for example on
In a second angular position of the support 32 of the lens 31, shown for example on
Of course, the geometry of the support 32 allows it to remain out of the optical path at all angular position of this support 32.
The support 32 is pivotally mounted in order to be able to pivot about a rotation axis X1 perpendicular to the optical path of the light beam at the position of the lens 31 when it is place in the first angular position. In other words, the rotation axis of the lens 31 is perpendicular to the optical axis L of the lens 31.
In the example described here, the lens 31 is of rectangular shape. It is inserted inside a frame that surrounds its edge. Two triangular branches link the frame to the pivot axis of the lens 31. A rectangular ring keeps the lens 31 in place in the frame. This ring is mounted thanks to screws on the sides of the frame facing the pivot axis.
Preferably, the visual test screen 21 is movable in translation along two perpendicular directions for centering this screen 21 relative to the other optical component of the optometry device 100, in particular relative to the optical axis L of the lens 31 in its active position.
Motorized active recentering of the first screen 21 may be implemented. Alternatively, the screen may be centered for predetermined fixed positions only.
Thanks to the adjustment devices, the screen 21 is accurately centered relative to the optical center of the lens 31. This centering step ensures that the light emitted at the center of the screen exits the optometry device at the center of the exit aperture 10A.
The size of the mirrors and lens is chosen to be wide enough to enable easy centering of the visual test image. The minimal distances between screen, mirrors and lens may also be enlarged to facilitate this centering.
Moreover, in addition to this physical centering of the screen, a numerical centering correction may be applied to the visual test picture displayed by the screen 21 in order to compensate predetermined deviation of the screen or other optical component, in particular the reflecting surfaces in predetermined configurations of the device. This numerical centering correction consists in shifting the visual test picture on the screen in order for it to appear centered relative to the exit aperture. The control unit 28 may be programmed to implement this correction of the visual test picture.
The physical and numerical centering adjustments aim at maintaining said visual test image visible for the eye 1 of the individual through the exit aperture 10A of the optometry device 100 centered for all relative positions of the optical components of the device.
Thanks to the adjustment devices, the visual test picture displayed by the visual test screen 21 may be accurately centered relative to the optical axis L of the lens 31.
When the first screen 21 and/or the visual test picture displayed by the screen 21 is accurately centered on the optical axis L of the lens 31, the screen axis considered at the center of the picture displayed, the optical axis L of the lens 31 and the optical path of the light coincide inside the display unit 20.
Between the display unit 20 and the refraction test unit 10, the optical path of the light may deviate from the optical axis L of the lens 31, as the refraction test unit 10 and thus the exit aperture 10A are placed on front of the eye 1 of the individual and may therefore be shifted relative to the optical axis L of the lens 31.
In the embodiment described here in more details, the acuity module 20A of the display unit 20 also comprises at least one reflecting surface 41. This reflecting surface 41 is arranged in the optometry device 100 in order to direct the optical path toward the exit aperture 10A of the refraction test unit.
The reflecting surface 41 allows folding the optical paths of the light beams emitted by the screens 21, 22, in order to limit the size of the display module 10.
In practice, the at least one reflecting surface comprises at least one mirror 41, preferably between two and four mirrors.
Alternatively, said reflecting surface may comprise any kind of beam splitter. Or, alternatively, in a simplified embodiment, the optometry device may comprise no reflecting surface at all. In this kind of embodiments, the first screen is then placed on the optical axis of the lens or of the optical element, and preferably movable in translation along the optical axis of the optical element. The optical axis of the lens is then straight, as it is not folded by the mirrors.
Moreover, the at least one reflecting surface may be movable in translation and/or in rotation between at least two positions.
The reflecting surface may be movable in order to further vary the distance between the visual test image and the exit aperture.
The second projection sub-system or “scene module” 20B comprises here the second or scene screen 22 and an additional mirror 24. The additional screen 22 is used to display the background picture. This background picture is preferably of an environment familiar to the individual, for example a natural environment, exterior or interior, such as a city, a landscape or a room.
The additional mirror 24 is here a concave mirror. Its optical axis goes through the summit of the concave mirror 24 and is here overlapped with the optical axis L of the lens 31 of the acuity module 20A at the exit from the display unit 10.
The additional screen 22 may be a video display, for instance an LCD display, or any adapted screen of the type described earlier in reference with the visual test screen 21 of the acuity module 20A.
A beam splitter 26 is placed between the acuity module 20A and the scene module 20B in order to superimpose the light emitted by the screen 21 of the acuity module 20A (visual test optical path) and the light emitted by the second screen 22 of the scene module 20B (background optical path).
Advantageously, the beam splitter 26 is positioned such that it reflects the light coming from the first screen 21 of the acuity module 20A towards the refraction test unit 10 and, ultimately, towards the eye 1 of the individual. It also reflects the light emitted by the second screen 22 towards the additional mirror 24 and let the light reflected by the latter travel straight through it towards the eye 1 of the individual. Both light beams, coming from the acuity and scene modules 201A, 20B exit the casing 2 of the display module 10 through an opening 3.
As represented in
In alternative embodiments, first screen and the second and third mirrors may be mobile in translation and/or rotation.
The first mirror 41 is here placed on the visual test optical path and mounted to pivot about a rotation axis X1 perpendicular to the optical path of the light beam, in order to be alternatively placed at an angle of 45° or 135° relative to the screen axis S of the visual test screen 21.
Hence, the light emitted by the screen 21 can here follow one of three optical paths (all are “visual test optical paths”), depending on the angular position of the first mirror 41.
When the first mirror 41 is in the first position (45° to the screen axis S), and the optical element 30 is in its active position (
The distance between the visual test image produced by the projection optical system 20A, 20B and the exit aperture 10A is then about 6 meters: the visual test picture displayed by the visual test screen 21 is then seen at a distance of about 6 meters (more or less equivalent to “infinity”) by the eye 1 of the individual. With no other modification, the optical element 30 may be pivoted to its retracted position. The distance between the visual test image OPT and the exit aperture 10A is then about one meter.
The first mirror 41 may then be pivoted from its first position (
The visual test image may therefore be displayed at three fixed distances from the exit aperture of the device.
With this optometry device 100, the visual test image OPT (the one containing the figures to test the acuity of the eye) may be observed at three (or even more) different optical distances by the individual.
It should be noticed that that the actual sizes (height×width H×W in cm2) or apparent sizes (angular height×width in degrees) of the visual test images OPT at different distances D1 are usually different due to the fact that the overall dimensions of the first screen 21 are constant whereas the visual test distances D1 or projection are variable.
As already explained,
Here, as shown in
The visual test image OPT or “optotype” (as it is designed to test the acuity) is represented in the form of a road sign placed far away above the road on which the car is running. The visual test image OPT shows here a sequence of capital letters, from left to right: ‘H’, ‘E’, ‘T’, and V′. In the case of
On this
For other visual test distances D1, for example smaller than far distance, the visual test image appears to the individual greater in size and occupies a bigger space on the scene image, with the same shape and aspect ratio of the visual test image OPT observed at far distance. The superimposition area between the two images is also bigger in size.
Whatever the visual test distance D1 is, if nothing is done on the different pictures displayed on the screens 21, 22 of the display unit 20, the visual test image OPT would be projected on a bright region of the scene image SCN of the superimposition area, and would have its contrast disturbed by the luminance of the scene image in this superimposition area.
Moreover, for other visual test distances D1 (there could be more than 5 meters differences between near and far visual test image distances), the visual test image appears to the individual with a different (bigger in the present example) size though with the same shape and aspect ratio so that it may influence badly how the optotypes OPT (letters) are seen by the driver.
That is the reason why the present invention is interesting. Indeed, according to the invention, in the optometry device 100 described above, the at least one control unit 28, 29 is configured to define in the scene picture at least one scene zone implying transparency for the corresponding virtual scene image and in the superimposition area between the visual test image and the scene image, allowing the individual's eye to observe the functional zone of the virtual visual test image OPT without contrast decrease, at the visual test distance D1.
Moreover, the control unit is configured to modify the luminance or colorimetry distribution of the visual test image OPT and/or of the scene image SCN based on the visual test distance (first distance D1) of projection of the visual test image OPT.
Therefore, it is possible to change the way the different projected images are seen by the individual.
In some embodiments, the at least one control unit may also be configured to perform the luminance/colorimetry modification as a function of the visual test distance (first distance D1) of projection.
In some embodiments, the at least one control unit drives the projection optical system to produce a visual test picture whose luminance depends on the main color temperature, preferably according to the Kruithof's curve. For example, for a color temperature of 5000° K, the luminance of the scene screen will be set at 120 cd/m2 and for 5500° K, the luminance of the acuity screen will be set at 160 cd/m2 for defining a bright background, and to 85 cd/m2 for defining a dark background.
In possible embodiments where the optometry device comprises only one control unit, this unique control unit is configured to control both the first and second projection sub-systems 20A, 20B, and more particularly the first and second screens 21, 22.
In other embodiments, like the one represented in
Because the optical image of the “acuity” channel is a virtual image for the individual, the scene image SCN of the “scene” channel projected by the second projection sub-system 20B appears in transparence through the acuity channel in such a way that the visual test image, i.e. the optotypes OPT, is seen by the individual with a low or lower contrast, rendering its recognition more difficult or longer.
Hence, in order to overcome that particular problem, the second control sub-unit 29 of the scene module 20B drives the scene screen 22 to apply a zone implying transparency on the scene image SCN, the zone implying transparency having a shape and an aspect ratio substantially identical to a shape and aspect ratio of the visual test image SCN.
In other words, and as shown in
In practice, the zone implying transparency 50 is created by driving the corresponding pixels of the scene screen 22, and more precisely by decreasing/suppressing their luminance level. For example, the colorimetry distribution of the zone implying transparency is configured by the control unit to have a low luminance inferior to 100 cd/m2, preferably to 50 cd/m2, more preferably to 30 cd/m2.
Preferably, the zone implying transparency 50 presents a size (height×width in the scene image) which is larger than a size of the visual test image OPT (here the size of the road sign in
This larger size allows taking into account the fact that the inter-pupillary distance of the subject (i.e. the physical distance between the two centers of the pupils of the eyes 1 of the individual) induces a parallax effect when the visual test image is observed with left and right eye.
The oversize of the patch 50 depends of course upon the visual test distance D1 of projection of the visual test image OPT.
Advantageously, the projection control unit 29 drives here the scene screen 22, to produce a scene picture so that a peripheral zone 51 of the scene image SCN is fuzzy, as represented on
By doing this, it is possible to use the same zone implying transparency whatever the inter-pupillary distance of the subject is.
This fuzzy contour of the scene image SCN is obtained directly by letting the corresponding pixels of the second screen 22 display a background picture with fuzzy regions.
Preferably, the zone implying transparency has a relative position in the scene image SCN (i.e. the scene in which the visual image is included) which depends on the tested individual's eye 1 (left, right, or left and right eyes for binocular tests) and also on the visual test distance D1 of projection.
In this way, it is possible to overcome parallax effects during the visual tests. For, the zone implying transparency 50 in the scene image SCN is positioned so that it is superimposed in the region of the optotypes OPT, thus decreasing the background luminance in this region and then increasing the visually perceived contrast of the optotypes by the eye 1 (or eyes) of the subject.
For a far vision (FV) visual test, as represented on
When we mask one eye of the subject to test the monocular vision, a parallax effect occurs. The parallax is an effect due to the change of incidence of the line of sight of the patient, that is a change of position of the observer while observing an object (e.g. the optotypes OPT on the road sign of
For example, when we test the right eye 1, the black rectangle 50 should be shifted to the left and in the opposite direction if the left eye is under test.
Here, the black rectangle 50 has a width (W) of 127 mm and an height (H) so that the aspect ratio W/H of width/height is the same as Full HD, that is W/H=1920/1080 (≈1.78).
Moreover, we “add” a 20% blur to the rectangle 50 then creating the blurry contour (or fuzzy edges) shown in
The fuzzy edges imply a larger size of the zone implying transparency 50, for example of 10, 20 or preferably 25% larger in size. The perception of transparency and the width of the fuzzy edges can be chosen according to the specific scene image and to the specific acuity image. The skilled man can chose the best transparency/width of the fuzzy edges further to different trials made with the same specific scene image and to the specific acuity image and different transparency/width of the fuzzy edges. The transparency/width of the fuzzy edges implying the best esthetical perception of the integration of the acuity image to the scene image will be selected for this specific scene image and the specific visual test (acuity) image.
For a monocular near vision (NV) visual test, we can use the same rectangle as the one of
For a binocular near vision (NV) visual test, we must use a large or larger patch such as the black rectangle 50 represented in
In this figure, the zone implying transparency is used for a 40 cm visual test, thus in near vision, for both eyes (binocular). The rectangle 50 has a width (W) of 253 mm, again with a full HD aspect ratio of 1920/1080 and a 20% blur on the edges 51 of the rectangle. The width of the zone implying transparency 50 then becomes 363 mm and is centered on the scene channel.
That widening of the zone implying transparency is needed due to the fact that the projection of the visual test screen, that is the visual test image OPT, in the scene channel is wider for near vision/small distances (test image at 40 cm and scene image at infinity) than for far vision/large distances (test image at 6 m and scene image at infinity).
Displaying a larger black rectangle in that case allows:
Because the size of the visual test screen 1 is fixed (constant) and because the optical formation of the visual test images OPT through the acuity channel (visual test optical path) is done with different image magnification for different visual test distances D1 of projection, the apparent size of the visual test images OPT varies greatly between far, intermediate or near vision.
Indeed, when we perform a visual test at a nearer distance (i.e. first distance D1), then the visual test image OPT appears globally bigger than at farther distances.
Therefore, in order to keep the same apparent size L×l of the test image i.e. the functional part including the optotypes and their background, the visual test control unit 28 drives the projection sub-system 20A to produce the visual test images OPT from a visual test picture with a frame implying transparency 52 surrounding the functional zone L×l of the visual test picture. The frame 52 shape features are modified based on said visual test distance D1 so as the functional zone of the visual test image OPT has a shape and an aspect ratio L×l substantially identical for different visual test distances D1.
Indeed, when we apply a dark/black region like a frame on the visual test picture produced by the screen 21, it appears for an observer, i.e. for the eye 1 of the patient, as being transparent in the visual test image, thus allowing the vision of the scene image SCN (scene channel) corresponding portion through it.
The
Advantageously, the black frame has a rectangular shape and the same aspect ratio as the first screen 21. The exterior of the black frame 53 has the same size as the acuity screen 21. Then, the “thickness” of the black frame 53 is adjusted by the projection optical system as a function of the visual test distance D1 of projection.
More precisely, in order to obtain the same apparent size L×l of the visual test image OPT at any visual test distance D1 of projection, we create a black frame on the visual test picture displayed by the screen 21 of the acuity module 20A.
It can be done easily, for example by darkening (i.e. decreasing the luminance) or even switching off the corresponding pixels of the first screen 21.
In
Here, the variation of the image magnification of the second optical sub-system 30 is 0.533 (the NV test image is thus around 1.88 times bigger than the FV test image), the visual test image OPT will thus appear with the same overall size in near vision and in far vision conditions.
For specific visual test image implying bright optotypes in a dark background, in addition to the above possibilities considered alone or in combination, a positioning frame can be produced in the visual test picture to make said bright optotypes in a dark background, perceived by the individual as being positioned at a particular depth of observation.
Indeed, without such a frame, said bright optotypes shown in a dark background are observed by the individual in an also dark scene image, the bright optotypes would appear as floating in the image, what can disturb the individual.
The positioning frame acts is perceived a support for the optotypes what can be conceived by the individual brought to handle the refraction test without disturbance.
For this purpose, the control unit 28, 29 is configured to define:
Of course, preferably, an adapted frame implying transparency in the visual test image 53 as disclosed above can also be defined around the positioning frame 54 so as to ensure the functional zone 52 surrounded by the positioning frame to show substantially identical size, shape and aspect ratio for different visual test distances D1.
Preferably, the positioning frame will be defined with a realistic shape according to the pending visual test distances D1. Accordingly, for short visual test distances D1 to determine refraction at near distance, the positioning frame can take the form of an object usually looked at near distance and defining a frame, such as a smartphone. The positioning frame will be defined so as to match the shape/aspect ratio and apparent size of the surrounding edge of said smartphone looked at the chosen visual test distance. On the contrary for long visual test distance to determine refraction at far distance, the positioning frame can take the form of an object usually looked at far distance and defining a frame, such as a road sign. The positioning frame will be defined so as to match the shape/aspect ratio and apparent size of the surrounding edge of said smartphone looked at the chosen visual test distance.
Now, we will discuss how the colorimetry changes are handled in the optometry device of the invention.
Because the different optical paths in the optometry device 100 are different and also vary between a near vision test and a far vision test (at least for the visual test optical path), then the luminance and the colorimetry (e.g. color temperature) of the visual test image OPT (acuity channel) can also change for the patient doing a refraction test at different distances.
Therefore, in preferred embodiments, the first control unit 28 of the optometry device 100 drives the projection optical system 20A (acuity module) to produce a greyscale visual test image having a white color temperature and an overall luminosity which are constant with varying visual test distances D1 of projection.
Like this, it is possible to keep the same lighting/color conditions of the visual tests at variable image distances.
In practice, we adjust two parameters:
These two parameters are directly adjusted in the visual test picture displayed by the first screen 21.
Moreover, in order to bring even more comfort to the patient, the brightness and color temperature of the scene screen 22 is different from those of the acuity screen 21.
All those techniques are really easy to implement and they allow performing visual tests in a compact system and in a comfortable manner for the patient.
In an example embodiment of the optometry device 100, it has been determined, on one hand, that the output luminance of the scene image SCN (measured with a spectrophotometer) should be, at any distance, equal or higher than 350 cd/m2. On the other hand, the output luminance of the screen 21 in the acuity channel should be above 375 cd/m2 at any test distance.
To obtain these values, it is possible to adjust the brightness and/or the white point of each backlight unit of the screens 21, 22 (if they are standard LCD displays).
For example, we determined that the overall color temperature that is needed for the screens 21, 22 is around 5000 K±200 K. To obtain that value, the color distribution of the background picture (scene channel) and of the visual test picture (acuity channel) are adapted and chosen as a function of the visual test distance D1 of projection.
The above mentioned optometry device 100 as illustrated in
The object of another aspect of the invention, is to provide to the subject specific global images i.e. including acuity and scene images whatever their constitution (either deriving from the superimposition of a visual test (acuity) and a scene image as disclosed above, or constituted by a unique image containing both scene zone and acuity zone) during the refraction test specifically created and optimized to render the experience the more realistic while being the more convenient to determine refraction.
Of course the global image according to this embodiment as described below, could also be displayed on the screen of the above mentioned traditional refraction determination method but with less impression of immersion for the subject due to the physical distance with the screen and the external elements surrounding the latter, as disclosed in the
We revert now to the optical system as disclosed in the
It is however essential to provide the global image with a minimum of clues of perception that are usually naturally present in real life to reach the perception of immersive experience, otherwise the attempt to provide the more realistic image for the subject would lead to unwanted perception and therefore unwanted response from the visual and cognitive system of the patient and disrupt the proper performance of the visual examination.
Conversely, the inventors have discovered that cautions have to be taken not to reproduce in the global image all of the aspects encountered in natural observation at different distance of observation, to avoid the patient to adopt unwanted position that would deter the examination.
The proposed solution consists therefore in precisely defining the composition of the global image shown during the refraction test, in order to allow the correct performance of the visual examination carried out at several distances in an immersive environment while warrantying a correct posture of the patient.
This object is reached thanks to several elements of the global image acting as clues of distance perception combined with specific choice in the way the optotypes are displayed relatively to the patient.
More precisely, the global image according to the invention, as disclosed on the
And when the global image is composed of the superimposition of an acuity image to a scene image, formed respectively from a scene picture and an acuity (visual test) picture as disclosed above, the vanishing lines 60 are oriented toward the zone implying transparency 50 and the acuity picture takes the form of a panel seen from the front and wearing symbols positioned flat thereon.
More precisely, the comparison between the
To test in the more realistic conditions the near/intermediate vision, the symbols used to determine refraction are disclosed on the image as being integrated in an object used to be observed at the chosen near/intermediate distance by a subject (a laptop 61 in the present example, a smartphone, a book, a menu card for other near/intermediate vision testing . . . ).
Also, the scene surrounding this object 61 disclosing the symbols is chosen to incorporate in the most realistic manner said object observed at the chosen distance.
In the illustrated example, this surrounding scene comprises tables of a meeting room disposed in a C configuration, with two opposite rows of table and corresponding rows of chairs disposed along the vanishing lines, acting as clues of perspective perception, the laptop being disposed in a front row of tables, at the center of the picture. The impression for the subject is to look at the screen, while being sitting on a chair facing said table, knowing that the subject is sitting on a chair during the test, looking straight forward through the phoropter of the optical system). The laptop supported by the table and more specifically its frame and keyboard act as a transitional element between the screen of the laptop displaying the symbol and the environment meeting room.
Vanishing lines 60 are displayed thanks to the rear edges of the lateral tables and thanks to the lateral edges of the central table on which the laptop is disposed, as converging toward points P disposed above or into the functional zone wearing the optotypes (the laptop's screen) and in any case, close to an horizon line. They moreover appear to be symmetric one another.
Even if the angle of view from above of the
Therefore the straight angle of view of the
Therefore, for any testing distance, the object wearing the symbols to determine refraction are placed in a plane perpendicular to the straight portion of the light beam 23 exiting the optical system's aperture 10A therefore also perpendicular to the ground.
In the scene depicted, it is moreover important to disclose the symbols used to determine refraction, on an object that fits into the environment. This object must be centered, have a controlled size and be at a coherent virtual distance from the observer (about 6 m in our example for far vision testing and about 40 cm for near vision testing, and between 40 cm and 6 m for intermediate vision testing). The object must be able to be found usually in this context, there must be a link (transition element) between the scene and the support of the object so that it is well integrated and that it is realistic. In addition, the support of the object and the object itself must be universal and present a size that will allow to integrate visual tests while being specific to the condition: e.g. in far vision the object can be a 5° panel, while in near vision the object can be larger (e.g. the contours of a smartphone: 10°). For example, a wooden sign on a country road. For different testing distance, a frame implying transparency can be used in the acuity images, with specific dimensions to render the functional zones of said acuity images for different testing distance, identical in shape and dimensions.
For example, as illustrated on the
In the illustrated example of the
With this scene, the observer is experiencing a realistic experience, i.e. the same kind of situation as when driving a car sitting on the car seat and looking at the urban road sign, thanks to the perspective perception brought by the vanishing lines, and several repeated/superimposed elements.
However, for the reasons explained above, knowing that the subject is sitting on a chair during the test looking straight forward through the phoropter of the optical system, the angle of view chosen for the subject observing the urban road sign, is not an arising angle of view, as would be in a real situation, but is a straight angle of view and the road sign is instead illustrated seen from the front, with no tilt angle and so are the symbols disposed thereon.
The
Concerning the type of element to be used in an environment, when using a still (fixed) image, it is best to limit the presence of elements that are usually moving in a real environment. Indeed, if we integrate usually moving elements (birds in the sky, persons dancing, jumping, walking . . . ) in a fixed image, this would automatically disrupt the subject's attention, but the presence of living elements displayed in static could give a feeling of oddity. We will therefore endeavor to limit the addition of people and animals in a moving situation, and naturally moving elements (river, waterfall).
Moreover, shadows and reflections 81 smartly spread respectively around or in some of the different elements can act also as clues of perspective perception (thus the shadows of the trees, street light, metallic structure of the
It was noted that the quality of the image definition and its rendering are particularly important to participate in the realism of the stimulus. Thus, there must be consistency in lighting: depending on the position of the subject, the sun and the shadows. In general, it is necessary for the situation to be known in terms of a bright and relaxing atmosphere while providing a certain unity. The colors can be soft and not garish, united but realistic (sky with large white clouds bringing texture.) In order not to disturb the subject's attention, it is important not to add bright colors at the periphery, or light sources (e.g. reflections on water, . . . ) which may cause any discomfort to the light. It is also important to propose textures to have a realistic and comfortable scene without too repetitive patterns, that are realistic and not disturbing for the subject.
In addition, different levels of blur defined for areas of the scene picture disposed along the vanishing lines, can also act as clues of perspective perception. As such the background areas (mountains 80 on the country
For the other areas than the background area, the level of blur progression will depend on the testing distance D1:
A particular advantage of the invention is to also make the symbols used in the test fit to the context of the surrounding scene. As such, the symbols appearing to be displayed on the laptop 61 of the meeting room
These symbols appearing on the same object can moreover be different in shape, size, in contrast level, in spatial frequency, in texture, in orientation, in kind among letters, symbols, numbers, pictograms, and/or in relative contrast among reverse contrast (bright symbol on dark wooden background as for
Indeed, the test integrated into the object situated in the scene should make it possible to discriminate various visual defects. For this, the test integrated into the object must include several types of stimuli and must have several degrees of difficulty of recognition. The symbols presented must be varied. In addition, they must be universal. For example, a test can be made up of a combination of letters, numbers, and pictograms. It can have different sizes of elements (3/10th to 10/10th), different spatial frequencies, and different textures (wooden planks). It can also include high and low contrasts or reverse contrasts (black on white & white on black) as well as different orientations. Finally, it must include current and short stimuli (Ex: word Taxi, pictogram of a car, . . . ) and not just letters of the alphabet.
The
The
As will be easily understood, the features depicted above for appearing on the object (road sign, laptop.) disclosing the symbols testing refraction i.e. the texture, the several symbols, the colorimetry distribution/illustration fitting to the environment scene of the object, can be set on the image picture, and the features depicted above for appearing in the environment of the object (texture, transition element, different types of clues of perspective perception . . . ) can be set on the scene picture.
Otherwise, when the global image including the object and its environment is defined by a unique global picture and no more by superimposed acuity and scene pictures, said features appearing on the object, and in the object's environment will be set on said unique global picture.
The above principles applied to an image shown during a refraction test, can be used to define a video optimized for the same purpose.
In order for the video to be realistic, there has to be characters, and more generally life in the video. In addition, the movements shown to the observer must not be perceived as being too abrupt, at the risk of creating an uncomfortable situation for the patient (acceleration, limited deceleration, etc.) by offering too much image flow. Also, the rotational movements of the camera may be perceived as strange for a patient keeping his gaze fixed, they will therefore be avoided. For the best experience and comfort for the patient, the presence of danger elements (precipice, fire, weapon, car accident, explosion . . . ) will be avoided in the video.
For example, an appropriate video would involve a sequence of images wherein the observer is sitting in a car as depicted on the
For example, such a video could simulate the wearing of sunglasses to make the subject simulate the relief brought by such equipment.
First of all, the patient must initially understand that he/she is in a very bright environment. To show this addition of light, it is worth moving from a dark to a brighter place. For example, the sequence of images can define for the observer driving a car driven on a road initially in the shade of a line of buildings and suddenly when the line of buildings ends, the sun is beating down on the car and dazzle the observer. This can be combined with an increase in the light level of the backlight of the scene and preferably the acuity screen.
In order to show to the patient the benefit of wearing corrective sun lenses, it is better to show vision loss rather than vision gain. Therefore, the sequence of image shown during the experience, needs to show at first to the patient the vision he/she would have with his corrective sunglasses (with the appropriate corrective power applied on the tunable lenses of the phoropter) and with the colorimetry distribution and shadow/reflection elements corresponding to a vision with sunglasses with correction, then in a second step with the same lighting conditions with sunglasses but without correction, to cancel the correction brought by the phoropter lens (zero power of correction or a power correction equivalent to a former equipment of the subject).
Here is a summary of an example video scenario for a sightseeing sunglass experience that could be built from a sequence of images among which at least a group of images fulfills the above requirements.
The patient is in a driving situation in a bright environment (very sunny road) and wears corrected polarized sunglasses (the correction being brought by the phoropter or the successive images being clear). He stops at a stop sign, reads the license plate and other information on panels, and then his corrective sunglasses are removed (cancellation of the correction brought by the phoropter or increase in the blur level of the successive images corresponding to the correction need of the subject and generation of a bright environment). He can no longer read the information he read previously. The car restarts, there are a lot of reflections on the sea, on the windows of buildings and the windshields of cars, and the light is strong. The car pulls into a parking lot at the end of the road, his corrective sunglasses are put back on (comfortable lighting conditions and correction brought by the phoropter or retrieval of clear images) and he can again see what is written on a banner pulled by an airplane, on the ice cream parlor's sign, on the menu card of a restaurant, while it was difficult without his glasses.
The invention concerns in addition to the embodiment of the
Indeed, during a traditional visual examination, the measurements are carried out in a high luminance environment. But this environment is not representative of all the conditions that the visual system may face. In fact, it has been observed that in low luminance conditions the visual system adapts to maintain a certain performance. In a low luminance environment the pupil dilates, aberrations tend to increase and accommodation is modified. It has been reported by several authors a phenomenon of nocturnal myopia, which causes reduced vision in users and is the cause of complaints of discomfort at night.
To implement such low luminance examination, certain constraints must be taken into account, such as reducing the brightness of the examination room, the time to adapt to darkness, and the number of sources of parasitic light that may interfere with the smooth running of the examination (e.g. computer screen light for example). Controlling the light environment of the examination room is a major issue in the successful assessment of subject complaints and the determination of refraction in nighttime conditions. This would allow professionals to assess the visual abilities of subjects in low-luminance conditions in order to provide them with equipment suited to their needs and complaints.
The optometry device and method according to the invention, aims at solving these issues specifically into optometry devices combining virtually two images defining a superimposition zone between each other, into which a contrast decrease occurs.
To this end, the combined image resulting from the virtual merge of the scene image and the visual test image is provided with a uniform colorimetry distribution with a low luminance level (lower than 100 cd/m2, preferably lower than cd/m2, more preferably lower than 30 cd/m2) thanks to the control unit that controls both visual test and scene pictures colorimetry distributions dependently one another to define a night driving and uniform light condition for the combined image.
Thus, the brightness of both screens are adapted according to the condition tested:
For example, as depicted on the
Also, the acuity picture providing the acuity image is controlled by the control unit to display visual test image in the form of a dark road panel with letters with an average luminance fixed in the same range as the scene picture i.e. respectively to have a low luminance level (lower than 100 cd/m2, preferably lower than 50 cd/m2, more preferably lower than 30 cd/m2.
Moreover in the scene picture, the scene zone implying transparency for the corresponding virtual scene image and in the superimposition area between the visual test image and the scene image, is set with a low level of color in the RGB color model, i.e. RGB triplet values being each, below 40, more preferably below more preferably below 20, more preferably below 10, more preferably below 5 and more preferably at zero, out of 255. For example the RGB triplet of the zone implying transparency of the scene picture is set to (0, 0, 0) resulting in black or pure black color. The use of such colorimetry distribution allows to avoid any remaining color appearing on the superimposition zone of the acuity and scene images or any contrast decrease.
A color in the RGB color model is described by indicating how much of each of the red, green, and blue is included. The color is expressed as an RGB triplet (r,g,b), each component of which can vary from zero to a defined maximum value. If all the components are at zero the result is black; if all are at maximum, the result is the brightest representable white.
These ranges may be quantified in several different ways:
These images could be used either combined with acuity pictures with corresponding luminance, and providing the screen picture comprises also a corresponding zone implying transparency.
Or be used as they are represented, in the same order in a video aiming at putting the subject into decreasing lighting exposure during a certain period of time to render more pleasant and therefore perceived shorter in time a 5 or 10 minutes transition phase between a first phase of the examination dedicated to day-light conditions, and a second phase dedicated to night conditions. This transition phase can be accompanied by corresponding relaxing sounds such as music, natural sounds.
The speed of decrease of the luminance level can be fixed at a predetermined value comfortable for the subject.
For example the disclosed four pictures are displayed in 12 s and figure begins with a luminance of more than 50 cd/m2 for example 60 cd/m2 and figure at a luminance below 10 cd/m2 such as 1 cd/m2.
Furthermore, the optometry device according to the invention can disclose in the pictures displayed by the scene screen and/or provide directly or indirectly, additional lighting spots imitating the kind of disturbing lights encountered at night (moon light, street lights, headlights of cars traveling in the opposite direction as disclosed in the
In a not illustrated embodiment, such light source can be brought by a specific light source as a LED, fixed inside the casing (either fixed on the scene screen around the picture displayed by the scene screen, or fixed on an inner wall of the casing on the optical path seen by the observer directly or further to a reflection on a mirror or beam splitter).
Moreover, to avoid disturbing reflection to occur on the main face of the visual test screen (21) and/or the scene screen (22), one or both of them is/are provided with an anti-reflective coating). For example, these coating can be constituted by any kind of film providing an anti-glare or anti-reflective effect, such as a multilayer structure of high index and low index alternating material layers, a mattified coating, a metalized coating or a coating provided with an electroplate treatment, with the aim of bringing an additional roughness to the external screen main face that reduces its brightness and therefore contributes to maintaining the contrast of the picture displayed and therefor of the combined image obtained from the scene and acuity images of corresponding screens.
And to isolate the subject from parasite lighting exposure coming from the examining room, the optometry device can be provided with a light isolating device as illustrated on the
More precisely, as shown on the
The rigid junction part of the light isolating device as illustrated on the
To allow an easy, simple and fast method of manufacture of the light isolating device, its constitution is made in two separate parts, one flexible and possibly standard, the second rigid and able to be 3D-printed and therefore with any shape allowing to define an interface on demand between any flexible mask, and any head support of any refraction unit.
Another option to decrease lighting parasite, is to use, for the keyboard and interface controlling the optometry device at the disposition of the expert testing the subject, to use a “night mode” in which the keyboard/mouse would have no back lighting, and the digital interface would have a dark background and slightly bright letters as the one of a GPS device set in night mode.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/IB2020/000895 | Oct 2020 | WO | international |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/079245 | 10/21/2021 | WO |
