Optometry device for testing individual's eye and associated method

Abstract

To provide a refraction measuring apparatus having a wide measurement range.SOLUTION: An optometry device 100 includes: a refraction test unit 10 having an optical system for providing different vision correction powers close to the eye of an individual; and a display unit 20 adapted to generate a visual test image, the visual test image being visible through an exit aperture 10A of the test unit of the optometry device and the display unit including a screen 21 adapted to display a test image used in generating the visual test image and at least one optical element 30 having an optical power. The optical element is emitted by the screen and presents an active state in which it exhibits a non zero refraction power placed on an optical path of the light exiting the device through the output aperture, and an inactive state in which it introduces no refractive power on the optical path in order for the visual test image to be produced at a variable distance from the exit aperture.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vision measurement device and related method for testing an individual's eyes. [Background technology]

[0002] The document EP 3298952 describes such a device, in which the screen is fixed, a fixed lens is positioned in the optical path of the image displayed by the screen, and the position of the individual's eyes is in the focal plane of the lens.

[0003] The field of view of a vision test display that an individual's eyes can see is quite narrow, and therefore alignment of the vision test display with the eyes is extremely important.

[0004] The optical distance between the screen and the aperture exit of the device can be changed by moving the mirror closer to or further away from the screen.

[0005] This arrangement only allows this optical distance to be varied over a reduced range, and only allows for the creation of visual inspection displays with a narrow angular width. Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide a device with a wider measurement range that provides more realistic refraction measurements tailored to the wearer. [Means for solving the problem]

[0007] The object is to provide a vision measuring device for testing an eye of an individual, the device comprising: a refraction test unit having an optical system for providing different vision correction powers in the vicinity of the eye of the individual; and a display unit adapted to generate a vision test image for the eye of the individual, the vision test image being visible through an exit opening of the test unit of the vision measuring device, the display unit comprising: a screen adapted to display a test image used in generating said visual test image; and at least one optical element having an optical power; This is achieved in accordance with the present invention by providing a vision measuring device that exhibits an operational state in which the optical element exhibits a non-zero refractive power positioned on the optical path of light emitted by the screen and exiting the device through the exit opening, and a non-operational state in which the optical element does not introduce a refractive power onto the optical path so that a visual test image is generated at a variable distance from the exit opening.

[0008] In particular, in one embodiment of the present invention, the optical element is movable between an operating position in which the optical element is positioned in the optical path of light emitted by the screen and exiting the device through the exit opening, and a retracted position in which the optical element remains out of the optical path so that a visual inspection image is generated at a variable distance from the exit opening.

[0009] In this embodiment of the invention, the optical element is movable between an operative position corresponding to an operative state and a retracted position corresponding to a non-operative state by physical displacement of the optical element.

[0010] In another embodiment of the invention, the optical element is preferably fixed and not movable, the optical element remaining disposed on the optical path of the light and having a variable refractive power that is adjustable between a non-zero value corresponding to the operating state and a zero value corresponding to the non-operating state.

[0011] In this alternative embodiment, the power of the optical element is varied between an operative state in which a non-zero optical power is provided by an optical element disposed in the optical path of light emitted from the screen and exiting the device through the exit opening, and a non-operative state in which the optical power of the optical element is set to zero. Thus, in the non-operative state, the optical element functions as if it remained out of the optical path. However, the optical element remains in the optical path of the light in both the operative and non-operative states of the optical element.

[0012] Therefore, by moving the lens between two positions or by modifying the refractive power of the lens, it is possible to modify the distance between the generated visual test image and the exit opening of the device and thus test an individual's visual acuity in different vision conditions, for example in a distance vision condition at infinity or in an intermediate or near vision condition.

[0013] Moreover, the optical element can therefore be physically removed from the light path by displacement to a retracted position, or optically removed from the light path by setting the refractive power of the optical element to zero in order to display the vision test image at a near viewing distance from the individual's eyes. This allows for a larger image size to be displayed for the vision test image in near viewing conditions. The larger image size allows for the display of text to be read and for the image to be more easily centered relative to the exit aperture of the device.

[0014] Therefore, the visual acuity measuring device according to the present invention can provide visual test images at at least two different optical distances from the exit aperture, thereby providing visual test images for testing the visual acuity of a subject under at least two different visual acuity conditions, while reducing the overall size of the visual acuity measuring device, where the different visual acuity conditions correspond to two different viewing distances of the visual test image.

[0015] In embodiments in which the optical element is physically removable from the optical path, the ability to move the optical element in and out of the optical path allows for a reduction in the overall size of the vision measuring device required to provide a visual test image for testing a subject's visual acuity in at least two different vision conditions, such as a near vision condition and a distance vision condition.

[0016] The smaller size of the vision measurement device makes it easier for eye care professionals to store and use.

[0017] Moreover, the field of view remains wide enough in all vision conditions to allow the display of a realistic vision test image or at least one vision test image that is more realistic than the state of the art. More realistic means that the image viewing conditions, such as optical distance and field of view, are closer to real-life viewing conditions.

[0018] In embodiments where the optical element is optically removable from the optical path, by using an optical element with a variable power, the variable power of the optical element can preferably be adjusted or tuned continuously over a range of optical power values. Thus, the subject can be presented with images shown at variable distances, which distances are continuously adjustable over a corresponding range of distances with seamless transitions between the different distances.

[0019] A further advantage of embodiments with optical elements having variable power is that they allow the use of a fixed (non-movable) screen positioned as close as possible to the optical element, with or without one or several reflective surfaces to fold the optical path, in order to define the most compact vision measuring device.

[0020] According to a further non-limiting feature of the device of the present invention, The variable distance is between the far vision distance and the near vision distance or the intermediate vision distance, the optical element is an optical lens; the optical element is rotatably and / or translatably movable between the operating position and the retracted position; the screen is translatable along a reference axis between two positions corresponding to different distances between the generated visual inspection image and the exit aperture; the screen is translatable along two orthogonal directions to center the screen relative to the optical axis of the optical element; the optical element is an optical lens in an operative position, the relative position of said screen and said optical element being adjustable so that the screen is located at a distance from said optical lens equal to a back focal length of said optical lens measured along an optical axis of said optical lens; the visual inspection image includes an inspection image displayed by the screen without the influence of an optical element, which may or may not be reflected by a reflective surface of the device, or an image of the inspection image projected by the optical element, which may or may not be reflected by a reflective surface of the device; the relative positions of the screen, the optical element and the exit aperture are varied to continuously vary the distance between the visual test image and the exit aperture over one or several optical distance ranges comprised between infinity and near viewing distance; at least one reflective surface is disposed within the device to direct the path of light emitted by the screen toward an exit aperture; the at least one reflecting surface is translatable and / or rotatable between at least two positions; said at least one reflective surface is translated and / or rotated to a position such that said at least one reflective surface directs light emitted by said screen towards an exit opening when the optical element is in an inoperative state, i.e. when the optical element remains out of the light path or when the refractive power of the optical element is set to zero; The angular size of the visual inspection image measured looking at the exit aperture is between 5° and 25°; the apparatus includes another screen adapted to display another image, the image of which is superimposed with the visual inspection image; The screen is one of the following: an LCD screen, a TFT screen, an LED or OLED screen, a silk screen (serigraphy) with a backlight screen, a display light projection screen with a miniature video projector.

[0021] More precisely, the angular size of the visual inspection image measured looking from the exit opening along the horizontal axis is preferably comprised between 5° and 15°.

[0022] The present invention also provides a vision measuring device for testing an eye of an individual, the device comprising: a refraction test unit having an optical system for providing different vision correction powers in the vicinity of the eye of the individual; and a display unit adapted to generate a vision test image for the eye of the individual, the vision test image being viewable through an exit opening of the test unit of the vision measuring device, the display unit comprising: a screen adapted to display a test image used in generating said visual test image; and at least one optical element having an optical power; 1. A method for testing an eye of an individual using a vision measuring device, wherein the optical element exhibits an operational state in which the optical element exhibits a non-zero refractive power positioned on an optical path of light emitted by the screen and exiting the device through the exit opening, and a non-operational state in which the optical element does not introduce a refractive power onto the optical path such that a vision test image is produced at a variable distance from the exit opening, comprising: generating the vision test image for the individual's eye based on the test image, the vision test image being viewable through the exit opening of the vision measuring device, through which the individual's eye can view the vision test image; changing the variable distance between the visual inspection image and the exit aperture by changing the state of the optical element between the operative state and the non-operative state; and evaluating the visual perception of said visual test image by at least one eye of an individual at different distances between said visual test image and said exit aperture.

[0023] The following description, with reference to the accompanying drawings, will make it clear what the invention consists of and how it can be achieved. The invention is not limited to the embodiments shown in the drawings. Thus, when features recited in the claims are followed by reference signs, it should be understood that such signs are included solely to enhance the comprehension of the claims and do not limit their scope. [Brief explanation of the drawings]

[0024] [Figure 1] This relates to a first embodiment of the present invention. [Figure 2] This relates to a first embodiment of the present invention. [Figure 3] This relates to a first embodiment of the present invention. [Figure 4] This relates to a second embodiment of the present invention. [Figure 5] This relates to a second embodiment of the present invention. [Figure 6] This relates to a second embodiment of the present invention. [Figure 7] This relates to a third embodiment of the present invention. [Figure 8] This relates to a third embodiment of the present invention. [Figure 9] This relates to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following description, identical or corresponding elements in each embodiment are referred to using the same reference numerals and will not be described in detail each time.

[0026] The light path is represented by a dashed line and the direction of propagation is indicated by an arrow.

[0027] The mobility of the optical components is indicated by the double arrows located adjacent to them.

[0028] The present invention relates to a vision measuring device 100; 200; 300; 400 for testing the eyes of an individual. Four embodiments of the vision measuring device 100; 200; 300; 400 according to the invention are shown in the accompanying drawings.

[0029] This vision measuring device 100; 200; 300; 400 according to the present invention comprises a refraction test unit 10 having an optical system for providing different vision correction powers in the vicinity of an individual's eye, and a display unit 20 adapted to generate a vision test image for the individual's eye, said vision test image being visible through an exit opening 10A of said test unit 10 of the vision measuring device 100; 200; 300; 400.

[0030] The refraction testing unit 10 is here separated from the display unit 20 .

[0031] The refraction testing unit 10 is interposed between the display unit 20 and the individual's eye. The refraction testing unit 10 is movable so that its position can be adjusted in front of the individual's eye. The display unit 20 is generally fixed. The refraction testing unit 10 is movable relative to the display unit 20 so that the relative positions of the refraction testing unit 10 and the display unit 20 can be adjusted.

[0032] The refraction testing unit 10 can be of any type known to those skilled in the art. Such a refraction testing unit 10 is commonly called a "phoropter." The refraction testing unit 10 is adapted to provide a variable optical correction to the eye of an individual looking through it.

[0033] In particular, the refraction testing unit 10 may include a standard optical system that presents different lenses with different optical powers in front of one or each eye of an individual, or presents no lens or a blank lens with no optical power.

[0034] The lenses having different powers are exchanged manually or preferably by power command (not shown), and these different powers are vision correction powers for the individual's eyes positioned nearby.

[0035] The refraction inspection unit 10 preferably includes an optical system with one or more lenses, such as liquid lenses, having adjustable power.

[0036] The refraction testing unit 10 is, for example, a vision compensation system as described in document WO 2015 / 155458.

[0037] The refraction testing unit 10 includes, for example, a lens with a variable spherical power.

[0038] The variable spherical power lens has, for example, a deformable surface whose shape (in particular its radius of curvature and thus the spherical power provided by the lens) can be controlled by moving a mechanical part (for example a ring), which can be driven by a motor of the refraction testing unit 10.

[0039] The refraction testing unit may also include a pair of independently rotatable lenses, each having a cylindrical power.

[0040] Each of the rotatable lenses can be rotated by the operation of other motors in the refraction inspection unit 10 .

[0041] The motor is controlled by a control unit such that the combination of the variable spherical lens and the two cylindrical lenses provides the desired spherical correction and the desired cylindrical correction for the individual's eye, as described in document WO 2015 / 107303.

[0042] The various elements of the refraction test unit 10 (such as the variable spherical lens, the cylindrical lens, the motor and the control unit) are enclosed in a housing 12 shown in Figures 7 and 8. This housing 12 is different from the casing 2 which encloses the display unit 20. The refraction test unit 10 and the display unit 20 are housed in separate casings.

[0043] Alternatively, the refraction testing unit and the display testing unit can be housed in a common casing, but typically the refraction testing unit and the display testing unit are located in different spatial regions of the vision measuring device, and these different spatial regions do not overlap.

[0044] In this embodiment, the vision measurement device includes two vision compensation systems as described above, each positioned in front of one of the individual's eyes, and the adjustable powers of these vision compensation systems are vision correction powers for the closely positioned individual's eyes.

[0045] The exit opening 10A of the vision measuring device 100; 200; 300; 400 corresponds to the opening of the refraction testing unit at which an individual may position their eye to look through the optical system, i.e., the phoropter or visual compensation system, of the refraction testing unit 10. This exit opening is centered on the optical axis of one or more lenses of the refraction testing unit.

[0046] However, the exit aperture is typically off-center with respect to the optical axis of the optical elements of the display unit, as will be explained in more detail below.

[0047] The refraction testing unit 10 optionally includes one or more elements designed to receive the individual's head and hold the head in a predetermined position relative to the refraction testing unit 10. This element may receive the individual's forehead, such as the illustrated element 11. Alternatively or additionally, the refraction testing unit may include an element for receiving the individual's chin.

[0048] Such refraction inspection units 10 are well known and will not be described in detail here.

[0049] The light beam emerging from the display unit 20 is directed towards the individual's eye through one or more lenses of the test unit 10. The individual's eye is directed towards the exit opening 10A of the test unit, through which the light beam emitted by the screen 21 emerges from the vision measuring device 100; 200; 300; 400.

[0050] The display unit 20 includes: a screen 21 adapted to display a test image used in generating said visual test image; at least one optical element 30 having an optical power; Includes:

[0051] According to the invention, the optical element 30 presents an operational state in which the optical element exhibits a non-zero refractive power that is positioned on the optical path of the light emitted by the screen 21 and exiting the device 100; 200; 300; 400 through the exit opening 10A, and a non-operational state in which the optical element does not introduce any refractive power on the optical path so that a visual inspection image is generated at a variable distance from the exit opening 10A.

[0052] In the illustrated embodiment, the optical element 30 is movable between an operating position in which the optical element 30 is positioned in the optical path of light emitted by the screen and exiting the device through the exit opening, and a retracted position in which the optical element 30 remains out of the optical path so that a visual inspection image is generated at a variable distance from the exit opening 10A.

[0053] The optical path is the path that a light beam emitted by the screen 21 at the center of the image displayed by the screen 21 takes as it traverses the display unit 20 to reach the exit opening 10 A of the refraction testing unit 10 .

[0054] The visual inspection image includes an inspection image displayed by the screen 21 without the influence of the optical element 30, whether or not reflected by a reflective surface of the device 100; 200; 300; 400, or an image of the inspection image projected by the optical element 30, whether or not reflected by a reflective surface of the device.

[0055] By "projected" it is meant that the image of the test image is formed by an optical element, such as a lens. The image of the test image formed by the lens is a virtual image of the test image.

[0056] When the optical elements are in the retracted position, the visual inspection image comprises the inspection image displayed by the screen 21. The distance between the visual inspection image and the exit aperture of the refraction inspection unit 10 is then the distance measured along the optical path between the exit aperture and the screen 21.

[0057] When the optical elements are in their operating position, the visual inspection image comprises an image (or projection) of the inspection image displayed by the screen 21 as viewed through the optical elements 30. This image is typically a virtual image. This image is located at an optical position, which may be, for example, at infinity.

[0058] The distance between the visual inspection image and the exit aperture of the refraction inspection unit 10 is then the distance between the exit aperture and the optical position of the visual inspection image. The optical element 30 may, for example, include an optical lens 31, as in the example described here.

[0059] If optical element 30 includes optical lens 31 , the image of the inspection image is the image of the inspection image viewed through lens 31 .

[0060] In the example described here, the optical element 30 comprises a single lens 31. This lens 31 may be a lens with a fixed or variable power. The lens 31 here is the only optical lens included in the display unit 20. Therefore, the lens 31 is the only optical lens enclosed within the casing 2.

[0061] According to the invention, the distance between the visual test image and the exit opening is varied between at least a far viewing distance and different near or intermediate viewing distances. The far viewing distance is typically comprised between infinity and 65-70 centimeters. The intermediate viewing distance is typically comprised between 65-70 centimeters and 40 centimeters. The near viewing distance is typically comprised between 40 centimeters and 33 centimeters.

[0062] Preferably, the relative positions of the screen 21, the optical element 30 and the exit aperture 10A are made to be variable in order to vary the distance between the generated visual inspection image and the exit aperture continuously over one or several optical distance ranges from infinity to near viewing distance.

[0063] In another embodiment of the vision measuring device according to the present invention, not shown in the figures, the optical element remains positioned on the optical path of the light and has a variable refractive power that is variable between a non-zero value corresponding to the operating state and a zero value corresponding to the non-operating state.

[0064] In this alternative embodiment, the optical elements are preferably fixed and not movable.

[0065] Except for these differences, the visual acuity measuring device according to this embodiment is the same as the embodiment described in detail below.

[0066] In many cases, an embodiment of a vision measuring device that can be used in two different ways can be considered where the optical element has a variable power but is nevertheless movable between an operative position where the optical path of light passes through the optical element and a retracted position where the optical element is out of the optical path of light, in which case the operative and inoperative states of the optical element can be obtained by physically moving the optical element or optically changing the optical power of the optical element.

[0067] Minimum configuration of visual acuity measurement device In a minimum configuration, the visual inspection images can be generated at only two different distances. 1) The visual test image may be generated at a first optical distance, i.e., a minimum optical distance, corresponding to the optical distance between the exit aperture and the screen, defined when the optical elements are in a retracted position or in an inoperative state, and the screen 21 is directly observed by the individual. In this configuration, no optical components or only one or several reflective surfaces are located on the optical path between the exit aperture and the screen. The screen is directly observed by the subject without the influence of the optical elements in a retracted position or in an inoperative state. This first distance preferably corresponds to a near or intermediate viewing distance (FIG. 8). 2) The visual test image may also be generated at a second optical distance, i.e., a maximum optical distance, corresponding to the optical distance between the exit aperture and a virtual image on a screen when the optical element is operatively positioned on the optical path between the exit aperture and a screen. The screen is indirectly observed by the subject through the optical element, and the subject observes the virtual image on the screen. This second distance preferably corresponds to a far viewing distance. The optical element is, for example, operatively positioned on the optical path so that the exit aperture is optically conjugate with the screen.

[0068] In this minimal configuration, the vision testing device according to the invention can be considered to include only a fixed screen and the optical element, which can be moved between a retracted position and an active position to generate vision testing images at two different optical distances. The optical element can have a fixed power. It is also possible to consider that the vision measuring device according to the invention includes only a fixed screen and that the optical element is of an adjustable type, i.e., has an adjustable optical power that varies from a zero value (inactive state) to a non-zero value (active state). In this case, the optical element has a variable power and is always kept along the optical path; only the optical power of the optical element is changed from one state to the other.

[0069] Minimum configuration with a reflecting surface to bend the optical axis There may be an increased need to provide a compact configuration for the visual acuity measuring device. However, if the optical element 30 is a lens, the screen 21 and the optical element 30 must be separated by an optical distance close to the focal length of the lens, which is known to be able to set the focal length to a few tens of centimetres (e.g. 80-100 cm) so as to provide the long distance visual acuity of the screen 21.

[0070] One or several reflective surfaces can be used to fold the light path and limit the size of the display unit.

[0071] Such reflective surfaces may be arranged such that both the screen 21 and the optical element 30 can be positioned in close proximity to each other (eg, less than 20 centimeters, or preferably less than 10 centimeters).

[0072] In this way, the optical distance between the screen 21 and the optical element 30 can be set to a distance closest to the focal length of the optical element 30, and the virtual image provided by the screen is viewed at conditions close to infinity (4 or 6 meters or more). Two viewing distances are obtained when the optical element is along the optical path (farthest viewing distance) and when the optical element is out of the optical path (closest viewing distance), respectively.

[0073] Improved configurations with more than two distances In the above configuration, at least one reflective surface may be used to eliminate a portion of the optical path that allows viewing at long distances when the optical elements are in an inoperative or retracted position, in order to also provide a minimum near viewing distance.

[0074] To this end, in the embodiment shown in the figures, the screen 21 and the optical element 30 are arranged so that the optical axis of the optical element 30 and the screen axis of the screen 21 are orthogonal to each other (taking into account that the screen 21 generates a light beam along a screen axis S that is orthogonal to the mean plane of the screen 21). Furthermore, the first reflective surface is mounted so as to be movable between a far / intermediate viewing position, in which it directs light coming from the screen 21 towards the successive reflective surfaces, and a near viewing position, in which it directs light coming from the screen 21 towards the exit opening rather than towards the optical element in its first operating position.

[0075] Preferably, said distance between the generated visual test image and the exit aperture can take on values ​​greater than 2, preferably greater than 3, greater than 4, greater than 5, between infinity and the near vision distance. For this purpose, the optical element can have a variable power and / or the screen can be translated, continuously or in steps, along the optical path of the light emitted by the screen. It is also possible to provide these different distances by providing one or more movable reflective surfaces. Each reflective surface can be translated or rotated. Each reflective surface can be moved in and out of the optical path of the light or can be moved along the optical path of the light.

[0076] In such an embodiment, the vision measuring device may not include reflective surfaces 41, 42, 43 intended to fold the optical path between the screen and the optical elements, and the screen axis and the optical axis of the lens are aligned and the screen 21 is defined to be translatable along this common axis to define several far / intermediate viewing distances when the optical elements are in an operative state and several near viewing distances when the optical elements are in a non-operative state.

[0077] Preferably, said distance between the generated visual test image and the exit aperture may take any value comprised between infinity and the near viewing distance, for which purpose the optical element may have a variable power and / or the screen and / or the reflective surface(s) may be translatable, in particular along the optical path of the light emitted by the screen.

[0078] In the different embodiments shown in the figures, the vision measuring device 100; 200; 300; 400 according to the invention comprises a casing 2 adapted to be placed on a table, for example, or mounted on a stand and placed on a table or on the floor.

[0079] The casing 2 here encloses a display unit 20. The inspection unit 10 is arranged outside the casing 2 and optionally mounted on the casing 2.

[0080] The display unit 20 here includes a clarity module 20A and a scene module 20B.

[0081] The clarity module 20A includes a screen 21 and an optical element 30.

[0082] The screen 21 may be, for example, one of the following: an LED or OLED screen, a silk screen with a backlight screen, a display light projection screen with a miniature video projector, an LCD screen or a TFT screen. The screen 21 generates a light beam along a screen axis S that is perpendicular to the mean plane of the screen 21. This light beam is intended to generate an image of an object, such as a visual target, for the individual using the vision measuring device.

[0083] In the example described here, the screen 21 is flat.

[0084] The test image displayed by screen 21 is, for example, a visual target. As known to those skilled in the art, other types of images adapted to test an individual's visual acuity may be used. Accordingly, clarity module 10 is designed to generate a visual test image (representing an object, such as a visual target) for the individual's eyes.

[0085] The optical element 30 here comprises an optical lens 31. The lens 31 here is an achromatic lens, for example, having an effective focal length of between 70 centimeters and 1 meter, preferably about 80 centimeters. The optical lens 31 comprises, for example, an achromatic doublet. The lens 31 can also be, for example, a single lens. If a single lens is used, this single lens preferably has an effective focal length of more than 80 centimeters, for example 82 centimeters, to suppress chromatic aberrations.

[0086] In the example described here, the lens 31 can be convex. In this case, its focal length and the relative position of the screen 21 and the exit opening can be determined so that the screen 21 is located at a distance less than or at most equal to the focal length of the lens. In this way, when the lens 31 is in an operative state, i.e., along the optical path and has an optical power different from zero, the lens 31 presents a virtual image from the screen at a larger size to the subject looking at the exit opening (magnifying glass effect). Furthermore, this virtual image is observed from the exit opening at a virtual distance greater than the optical distance that exists between the exit opening and the screen 21 when the lens is in an inoperative state, e.g., in a retracted position.

[0087] In the example described here, when the lens 31 is in an inoperative state, i.e. out of the optical path or has an optical power equal to zero, the minimum optical distance between the exit aperture and the screen 21 can be set to the near viewing distance, for example 40 or 33 cm (see Figure 8).

[0088] The effective focal length of the lens 31 corresponds to the optical power of the lens itself. The effective focal length is measured between the focal plane of the lens and a theoretical surface located within the lens. Because it is not easy to position an optical element relative to the lens using the effective focal length and the location of the theoretical surface is difficult to accurately determine, the back focal length may be used.

[0089] The back focal length of the lens 31 is measured along the optical axis L of the lens 31 between the apex of maximum diopter of the lens and the focal plane of the lens, i.e., from the back surface of the lens to the focal plane of the lens 31.

[0090] As will be explained later, the optical axis L is bent here using a reflective surface such as a mirror.

[0091] Alternatively, with smaller screens, such as small 1 inch screens with high resolution HD or Full HD, it is possible to use lenses with a short effective focal length, for example 20 centimeters, which can be used to obtain a more compact device.

[0092] Preferably, the optical element 30 and the screen 21 are arranged relative to each other such that the screen 21 is positioned at a distance from the optical lens 31 and at least one relative position between the optical lens 31 and the screen 21 is equal to the rear focal length of said lens 31.

[0093] Therefore, in the far-viewing configuration, the relative positions of the screen 21 and the lens 31 can be adjusted so that the screen 21 is positioned a focal distance behind the lens 31, while the lens 31 remains positioned in the light path.

[0094] In this way, the visual test image generated by the display module 20 can be positioned at infinity relative to the exit aperture, and therefore relative to the individual's eyes, and the distance between the generated visual test image and the exit aperture is set as infinity.

[0095] According to one embodiment of the present invention, the optical element 30 is movable between at least said first operating position, in which the optical path of the light beam emitted by the screen 21 towards the eye of the individual passes through the optical element 30, and said second retracted position, in which the optical path of this light beam avoids the optical element 30. If the optical element 30 is a lens 31, the light beam passes through the lens 31 when the lens 31 is in the operating position and does not pass through the optical lens 31 when the optical lens 31 is in the retracted position.

[0096] This allows the clarity module to generate images of objects at variable distances relative to an individual's eyes.

[0097] In fact, in all the embodiments described here, the optical element 30 comprises a lens 31. The lens 31 is fixed on a support 32 that is pivotally mounted on a part of the casing 2 of the device 100; 200; 300; 400.

[0098] In a first angular position of the support 32 of the lens 31, as shown for example in Figures 1, 4, 7 and 9, the support 32 is parallel to the optical path of the light and causes the lens 31 to intersect with the optical axis. The light emitted by the screen then passes through the lens 31. The optical path of the light at least partially follows the optical axis L of the lens 31.

[0099] In a second angular position of the support 32 of the lens 31, as shown for example in Figures 2, 3, 5, 6 and 8, the support 32 is inclined with respect to the optical path of the light, placing the lens 31 outside this optical path, so that the light beam emitted by the screen 21 does not pass through the lens 31.

[0100] Of course, the geometry of the support 32 allows it to remain out of the optical path in all angular positions of this support 32 .

[0101] The support 32 is pivotally mounted so as to be pivotable about a rotation axis X1 that is perpendicular to the optical path of the light beam at the position of the lens 31 when the support 32 is disposed at 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.

[0102] In the example described here, the lens 31 has a rectangular shape. The lens 31 is inserted inside a frame that surrounds its edges. Two triangular prongs connect the frame to the pivot of the lens 31. A rectangular ring holds the lens 31 in place within the frame. This ring is attached by a screw to the side of the frame facing the pivot.

[0103] In all embodiments described herein, the screen 21 is translatable along two orthogonal directions in order to center the screen 21 relative to the other optical components of the vision measuring device 100; 200; 300; 400, in particular relative to the optical axis L of the lens 31 in its operating position or operating state.

[0104] For this purpose, adjustment devices are provided for centering the screen 21 with respect to the optical axis L or optical center of the lens 31 when the lens 31 is in its operating position or state. In other words, the adjustment devices make it possible to optically center the screen 21 on the optical axis L of the lens 31. These adjustment devices include an adjustable support 23 for the screen 21. This adjustable support 23 can be moved in a plane parallel to the screen 21, which plane is in fact perpendicular to the screen axis S. This adjustment is made at the time of manufacture. The adjustment can optionally be repeated during the life of the device. The movement of the screen in this plane can be achieved manually, for example by means of micrometer screws, or automatically through a motorized system controlled by an electronic unit (not shown).

[0105] An electrically active re-centering of the screen 21 can be performed. Alternatively, the screen can be centered only relative to a predetermined fixed position.

[0106] The adjustment device allows the screen 21 to be precisely centered relative to the optical center of the lens 31. This centering step ensures that light emitted at the center of the screen exits the vision measuring device at the center of the exit aperture.

[0107] The sizes of the mirrors and lenses are selected to be wide enough to allow easy centering of the visual inspection image, and the minimum distance between the screen, mirrors, and lenses may also be increased to facilitate this centering.

[0108] Moreover, in addition to this physical centering of the screen, a numerical centering correction may be applied to the test image displayed by screen 21 to compensate for certain misalignments of the screen or other optical components, especially reflective surfaces, in certain configurations of the apparatus. This numerical centering correction consists of shifting the test image on the screen so that it appears centered relative to the exit aperture. The electronic unit may be programmed to perform this correction of the test image.

[0109] The physical and numerical centering adjustments are intended to maintain the visual inspection image visible to the individual's eye through the exit aperture of a centered device for all relative positions of the device's optical components.

[0110] By means of these adjustment devices, the image displayed by the screen can be accurately centered relative to the optical axis L of the lens 31.

[0111] When the screen 31 and / or the image displayed by the screen is accurately centered on the optical axis L of the lens 31, the screen axis is considered to be at the center of the displayed image, and the optical axis L of the lens 31 and the optical path of the light coincide inside the display unit.

[0112] Since the inspection unit 10 and thus the exit opening 10A are positioned in front of the individual's eye and may therefore be offset relative to the optical axis L of the lens 31, the optical path of the light may deviate from the optical axis L of the lens 31 between the display unit 20 and the inspection unit 10.

[0113] As will be explained in more detail below, in some embodiments, the screen 21 may also be movable, particularly along the screen axis S, to further vary the distance between the visual inspection image and the exit opening.

[0114] In such an embodiment (see the first and second embodiments), the screen 21 of the clarity module 20A is translatable along a reference axis between two positions corresponding to different distances between the visual test image and the exit aperture, this reference axis here being superimposed or parallel to the screen axis S.

[0115] In embodiments described in more detail below, the clarity module 20A of the display unit 20 also includes at least one reflective surface disposed within the device 100; 200; 300; 400 for directing the light path towards the exit opening 10A.

[0116] Said reflective surface makes it possible to fold the path of the light beam emitted by the screen in order to limit the size of the display module.

[0117] In practice, the at least one reflective surface comprises at least one mirror, preferably two to four mirrors.

[0118] Alternatively, the reflective surface may comprise any type of beam splitter.

[0119] Alternatively, in a simplified embodiment, the vision inspection device may not include a reflective surface. As in the embodiment described here, the screen is positioned on the optical axis of the lens and is preferably translatable along the optical axis of the lens, which is then aligned because it is not folded by a mirror.

[0120] Furthermore, the at least one reflective surface may be translationally and / or rotationally movable between at least two positions.

[0121] The reflective surface may be movable to further vary the distance between the visual inspection image and the exit aperture, as will be explained in more detail below.

[0122] The scene module 20B here includes an additional screen 22 and an additional mirror 24. The additional screen 22 is used to display a background image. This background image is preferably an image of an environment familiar to the individual, for example, a natural environment, an external or internal environment such as a city, a landscape, a room, etc. The additional mirror 24 here is a concave mirror. The optical axis of the mirror 24 passes through the vertex of the concave mirror and is here overlapped with the optical axis L of the lens 31 of the clarity module 20A at the exit from the display unit.

[0123] The additional screen 22 may be a video display, for example an LCD display, or any adapted screen of the type already described with respect to the screen 21 of the clarity module 20A.

[0124] In a variant, the additional screen may include an LED matrix and a light diffuser, the LED matrix being positioned behind the light diffuser to generate a soft ambient light surrounding the visual test image generated by the clarity module.

[0125] A beam splitter 26 is disposed between the clarity module 20A and the scene module 20B to superimpose the light emitted by the screen 21 of the clarity module 20A with the light emitted by the additional screen 22 of the scene module 20B. The beam splitter 26 is positioned to reflect the light coming from the screen 21 of the clarity module 20A towards the refraction testing unit 10 and ultimately towards the individual's eyes. The beam splitter 26 also reflects the light coming from the additional screen 22 towards the additional mirror 24, which directs the light reflected by this additional mirror 26 through the beam splitter 26 towards the individual's eyes. Both light beams coming from the clarity module and the scene module exit the display module casing 2 through an opening 3.

[0126] The exemplary embodiment shown in the figures will now be described in more detail.

[0127] The first embodiment, shown in Figures 1 to 3, is a more advanced embodiment.

[0128] In this first embodiment, the clarity module 20A includes three mirrors 41, 42, 43. The screen axis S is here horizontal. The main direction of the optical axis L of the lens 31 in the operative position or state is here vertical outside the portion of the optical axis L folded by the mirrors.

[0129] A first mirror 41 is disposed on the screen axis S. The first mirror 41 is movable to pivot about a rotation axis X2 perpendicular to the screen axis S. In a first position, the first mirror 41 is oriented at 45° to the screen axis S and reflects the light beam emitted from the screen 21 towards the second mirror 42 (FIGS. 1 and 2), and in a second position, the first mirror 41 is oriented at 135° to the screen axis S and reflects the light beam towards the beam splitter 26 (FIG. 3). The second position of the first mirror 41 can only be reached when the optical element 30 is in its retracted second position.

[0130] The second mirror 42 and the third mirror 43 are arranged at right angles to each other, and in addition, the second mirror 42 and the third mirror 43 are arranged at angles of 45° and 135° to the screen axis S.

[0131] With this arrangement, while the first mirror 41 is in the first position, a light beam generated by the screen 21 can be reflected in turn by the first mirror 41 towards the second mirror 42. The light beam is then reflected by the second mirror 42 towards the third mirror 43 and thereafter reflected by the third mirror 43 such that the light beam is directed towards the lens 31 along the optical axis L of the lens 31. Here, the main directions of the screen axis S and the optical axis L are perpendicular to each other.

[0132] The light beam passes through lens 31 (when optical element 30 is in the first operating position), reaches beam splitter 26 and is reflected towards the individual's eye.

[0133] In this first embodiment, the support 23 of the screen 21 is movable along the screen axis S. The support 23 is in fact adapted to slide, for example, on a first rail 51 mounted on the casing 2 parallel to the screen axis S. The distance between the visual inspection image and the exit opening can thus be modified by moving the screen 21. The movement of the screen 21 can be visualized graphically by comparing Figures 2 and 3. In Figure 2, the screen 21 is further away from the first mirror 41 and the optical element 30 than in Figure 3.

[0134] In addition, the second mirror 42 and the third mirror 43 are held together on a base 48 that is mounted on rails 52 of the clarity module 20A so that the mirrors 42, 43 are slidably movable parallel to the main direction of the optical axis L of the lens 31.

[0135] The distance between the generated visual inspection image and the exit aperture can be further modified by moving (e.g., by an electric motor and associated mechanism, not shown) the base 48 supporting the mirrors 42, 43.

[0136] The movement of mirrors 42, 43 can be visualized graphically by comparing Figure 1 and Figure 2. In Figure 1, mirrors 42, 43 are further away from optical element 30 than in Figure 2.

[0137] This allows the clarity module 20A to generate vision test images at variable distances relative to the individual's eye E.

[0138] The lens 31 here has, for example, an effective focal length of 823 mm with an accuracy of 10%. The back focal length is here 813 mm.

[0139] 1, the lens 31 is in a first operating position, the first mirror 41 is in a first position, and the second and third mirrors are in their extreme positions furthest from the lens 31. The screen 21 is also in its extreme position where it is positioned furthest from the first mirror 41, which is in its first position.

[0140] In the configuration shown in Figure 1, the different elements of the apparatus are arranged so that the screen 21 is located in the focal plane of the lens. Thus, the test image displayed on the screen appears to be at an infinite distance from the individual's eye. Therefore, the distance between the visual test image and the exit aperture is infinite. Therefore, the visual acuity of the individual's eye can be tested in far-vision conditions by assessing the visual function of the individual observing the visual test image.

[0141] The second mirror 42 and the third mirror 43 may then be slid from the extreme position shown in FIG. 1 to another extreme position closest to the optical element 30 .

[0142] 1, by moving second mirror 42 and third mirror 43 along second rail 52 and moving lens 31 from the operative position to the retracted position, the distance between the generated visual test image and exit opening 10A can be varied from infinity to approximately 68 centimeters. Thus, the visual acuity of an individual's eye can be tested in far-viewing conditions at any distance included between infinity and 68 centimeters.

[0143] Here, the mirrors 42, 43 can be continuously slid on the second rail 52, so that the distance between the visual inspection image and the exit opening can also be continuously varied in the range from infinity to 68 centimeters.

[0144] The field of view along the horizontal axis of the screen 21 is approximately 8°. The maximum visual acuity determined is 20 / 10, based on the fact that standard targets require a minimum of two pixels to form the inner shape of said targets according to PR NF EN ISO Standard 10938 and NF EN ISO Standard 8596.

[0145] Alternatively, the screen 21 may also be slid from the extreme position shown in FIG. 1 to an intermediate position (not shown) in which the screen 21 is closest to the first mirror 41 in the first position.

[0146] The corresponding distance between the visual inspection image and the exit aperture can be varied from 5.6 meters to infinity when moving only the screen, and from 1 meter to infinity when moving only the second mirror 42 and the third mirror 43 between their two extreme positions.

[0147] Alternatively, the screen and mirrors can be positioned to generate a vision test image located 6 meters from the exit aperture 10A, and the visual function of the individual's eye can be assessed at 6 meters. This measurement can allow for the calculation of visual function for a target placed at infinity, for example, by adding a spherical offset to the measured spherical correction. More precisely, visual acuity measured at 6 meters can be converted to visual acuity measured at infinity by adding an offset of +0.16 diopters, as is known in the art.

[0148] 2 of the first embodiment, the optical element 30, including the lens 31, is in a second, retracted position. The distance between the visual inspection image and the exit aperture is approximately 67 centimeters.

[0149] The screen 21 can then be slid from the extreme position shown in Figure 1 to an intermediate position (not shown) in which the screen 21 is closest to the first mirror 41 in the first position.

[0150] The second mirror 42 and the third mirror 43 may also be slid between the extreme position shown in FIG. 1 and said other extreme position nearest the optical element 30 .

[0151] By moving the screen 21 along the first rail 51 and the second and third mirrors 42 and 43 along the second rail 52, the distance between the visual test image and the exit opening can be varied from about 1 meter to about 50 centimeters. Thus, the visual acuity of an individual's eye can be tested in intermediate viewing conditions at any distance comprised between 1 meter and 50 centimeters.

[0152] Here, the screen 21 and mirrors 42, 43 can be continuously slid on the first rail 51 and the second rail 52, respectively, so that the distance between the visual inspection image and the exit opening can also be continuously changed in the range of 1 meter to 50 centimeters.

[0153] The field of view of the screen 21 is approximately 8°. The maximum visual acuity determined is 10 / 10, based on the fact that the target requires a minimum of 2 pixels to form the inner shape of a standard target.

[0154] In the configuration of Figure 3 of the first embodiment, the optical element 30 is still in the retracted position, and the first mirror 41 is in a second position pivoted toward the optical element. In this configuration, the light beam is reflected directly by the first mirror 41 from the screen 21 to the beam splitter 26 without being reflected by the second mirror 42 and the third mirror 43. Only the screen 21 can be moved to change the optical position of the visual inspection image and, therefore, the distance between the generated visual inspection image and the exit aperture. The second mirror 42 and the third mirror 43 are bypassed. The configuration of Figure 3 here corresponds to a distance of 33 centimeters between the visual inspection image and the exit aperture.

[0155] By moving the screen 21 along the first rail 51, the distance between the generated visual test image and the exit opening can be varied from about 50 centimeters to about 33 centimeters. Therefore, the visual acuity of an individual's eye can be tested in near vision conditions at any distance included between 50 centimeters and 33 centimeters.

[0156] Here, the screen 21 can be continuously slid on the first rail 51, so that the distance between the generated visual inspection image and the exit opening can also be continuously varied in the range of 50 cm to 33 cm. When the screen is slid between the two extreme positions on the first rail 51, the field of view of the screen 21 varies between 12° and 15°.

[0157] The screen 21 and the three mirrors 41, 42, 43 are controlled to move, for example, by an electric motor 19 and associated mechanisms, not shown.

[0158] The set points for the screen and mirror positions can be determined automatically by software that takes into account the visual function of the individual's eyes in identifying targets in the vision test image produced by the device.

[0159] The second embodiment, shown in Figures 4 to 6, is also an advanced embodiment.

[0160] The screen axis S is vertical as seen in the main direction of the optical axis L of the lens 31 in the operating position. Preferably, the optical axis L of the lens 31 and the screen axis S are partially overlapped. In this second embodiment, the support 23 of the screen 21 is also movable along the screen axis S. The support 23 actually slides on a first rail 51 mounted on the casing 2 parallel to the screen axis S. Thus, the distance between the generated visual inspection image and the exit opening can be modified by moving the screen 21. The movement of the screen 21 can be visualized graphically by comparing FIGS. 5 and 6. In FIG. 5, the screen 21 is further away from the optical element 30 than in FIG. 6.

[0161] In this second embodiment, the clarity module 20A includes four mirrors 61, 62, 63, 64.

[0162] The mirrors are here held together in pairs of two mirrors oriented at right angles to each other, with each pair of mirrors of the first and second pairs being supported by elements of supports 65, 66 slidably mounted on second rails 67.

[0163] Each pair of mirrors can slide independently along the second rail 67 .

[0164] In particular, the first pair of mirrors 61, 64 may be slid in and out of the screen axis S.

[0165] When the first pair of mirrors 61, 64 are arranged on the screen axis S, the first mirror 61 of the first pair of mirrors is arranged in front of the screen 21, on the screen axis S. The first mirror 61 is oriented at 45° to the screen axis S and reflects the light beam emitted by the screen 21 towards the second mirror 62 of the second pair of mirrors, which is oriented parallel to the first mirror 61. This second mirror 62 reflects the light beam towards the third mirror 63 of the second pair of mirrors, which is oriented at 90° to the second mirror 62. The third mirror 63 reflects the light beam towards the fourth mirror 64, which belongs to the first pair of mirrors and is oriented parallel to the third mirror 63.

[0166] The fourth mirror 64 reflects the light beam vertically along the main direction of the optical axis L of the lens 31 toward the beam splitter 26 .

[0167] With this arrangement, while the first pair of mirrors 61, 64 are arranged on the screen axis S, a light beam emitted by the screen 21 can be reflected in turn by the first mirror 61 towards the second mirror 62. The light beam is then reflected by the second mirror 62 towards the third mirror 63, and thereafter by the third mirror 63 towards the fourth mirror 64 and by the fourth mirror 64 towards the lens 31 along the main direction of the optical axis L of the lens 31. The screen axis S and the optical axis L here partially overlap.

[0168] The light beam passes through lens 31 (when optical element 30 is in the first operating position), reaches beam splitter 26 and is reflected towards the individual's eye.

[0169] When the first pair of mirrors is positioned in the optical path, the distance between the visual inspection image and the exit aperture 10A can be modified by moving (e.g., by an electric motor and associated mechanism, not shown) the base 66 supporting the second pair of mirrors 62, 63 relative to the base 65 of the first pair of mirrors 61, 64.

[0170] The movement of the second pair of mirrors 62, 63 can be visualized graphically by comparing Figures 4 and 5. In Figure 4, the mirrors 62, 63 of the second pair of mirrors are further away from the mirrors 61, 64 of the first pair of mirrors and from the optical element 30 than in Figure 5.

[0171] In Figure 4, lens 31 is in a first operating position. This lens has an effective focal length of, for example, 857 millimeters. A first pair of mirrors 61, 64 is positioned in the optical path of light emitted by screen 21. That is, a second pair of mirrors 62, 63 is in its extreme position, furthest from the first pair of mirrors 61, 64. Screen 21 is also in its extreme position, where screen 21 is furthest from the first mirror 61 of the first pair of mirrors.

[0172] In the configuration shown in Figure 4, the different elements of the apparatus are arranged so that the screen 21 is located in the focal plane of the lens 31. Thus, the image of the test image displayed on the screen appears to be at an infinite distance from the individual's eye. Therefore, the distance between the visual test image and the exit aperture 10A is infinite. Therefore, the visual acuity of the individual's eye can be tested in a distance viewing condition by assessing the visual function of the individual observing the visual test image.

[0173] The field of view of the screen 21 is approximately 9°. The maximum visual acuity determined is 16 / 10, based on the fact that the standard optotype used requires a minimum of 2 pixels to form the inner shape of the letters.

[0174] The screen 21 can then be slid from the extreme position shown in Figure 4 to an intermediate position, as seen in Figure 5, in which the screen 21 remains positioned in the optical path of the light beam but is closer to the first mirror 61 of the first pair of mirrors.

[0175] The second pair of mirrors 62, 63 may also be slid from the extreme position shown in FIG. 4 to another extreme position nearest the first pair of mirrors 61, 64.

[0176] By moving the screen 21 along the first rail and the second pair of mirrors 62, 63 along the second rail 67, the distance between the visual test image and the exit opening 10A can be varied from infinity to approximately 2 centimeters. Thus, the visual acuity of an individual's eye can be tested in far-viewing conditions at any distance included between infinity and 2 centimeters.

[0177] Here, the screen 21 and mirror can be continuously slid on the first rail and second rail 67, respectively, so that the distance between the generated visual inspection image and the exit opening can also be continuously changed in the range from infinity to 1.5 centimeters.

[0178] In the configuration shown in FIG. 5, the optical element 30, including the lens 31, is in a second, retracted position.

[0179] The screen 21 can be slid from the extreme position shown in Figure 4 to a position (not shown) where the screen 21 is closest to the first mirror 61 of the first pair of mirrors (in the optical path).

[0180] The second pair of mirrors 62, 63 may also be slid from the extreme position shown in Figure 4 to said other extreme position closest to the first pair of mirrors.

[0181] Thereby, the distance between the visual inspection image and the exit opening 10A can be continuously varied from about 70 centimeters to about 1 meter.

[0182] Therefore, the visual acuity of an individual's eye can be tested in intermediate viewing conditions at any distance within this range.

[0183] The configuration shown in Figure 5 corresponds to a distance of 67 centimeters between the visual inspection image and the exit aperture.

[0184] In the configuration of FIG. 6, the optical element 30 is still in the retracted position and the first and second pairs of mirrors 61 , 62 , 63 , 64 are slid so as to be positioned out of the path of the light emitted by the screen 21 .

[0185] In this configuration, the light beam is directed from the screen 21 to the beam splitter 26 without being reflected by any mirrors. In this configuration, only the screen 21 can be moved to change the length of the optical path. The first and second pairs of mirrors are bypassed.

[0186] By moving the screen 21 along the first rail, the distance between the visual test image and the exit opening 10A can be varied from about 50 centimeters to about 25 centimeters, and therefore the visual acuity of an individual's eye can be tested in near vision conditions at any distance comprised between 50 centimeters and 25 centimeters.

[0187] The configuration shown in Figure 6 corresponds to a distance of 33 centimeters between the visual inspection image and the exit aperture.

[0188] Here, the screen 21 can be continuously slid on the first rail, so that the distance between the generated visual inspection image and the exit opening can also be continuously varied in the range of 50 centimeters to 33 centimeters.

[0189] The screen 21, mirrors 61, 62, 63, 64 and optical element 30 are controlled to move, for example, by electric motors and related mechanisms, not shown.

[0190] The third embodiment shown in Figures 7 and 8 is a simplified modification of the first embodiment described above.

[0191] In this third embodiment, the clarity module includes optical components that are similar to those of the first embodiment, except that the screen 21, the second mirror 42 and the third mirror 43 are fixed and not movable.

[0192] As in the first embodiment, a first mirror 41 is positioned in the optical path and is mounted to pivot about an axis of rotation perpendicular to the optical path of the light beam so that it is selectively positioned at an angle of 45° or 135° relative to the screen axis S.

[0193] In this embodiment, the light emitted by the screen can follow one of three optical paths depending on the angular position of the first mirror 41 .

[0194] When the first mirror 41 is in the first position (at 45° to the screen axis S) and the optical element 30 is in the operating position (FIG. 7), light is reflected by the first mirror 41 towards the second mirror 42, by the second mirror 42 towards the third mirror 43, and by the third mirror towards the optical element 30 and the beam splitter 26. The distance between the generated visual test image and the exit aperture is then approximately 6 meters. That is, the test image displayed by the screen 21 is viewed by an individual's eye at a distance of approximately 6 meters.

[0195] Without other modifications, the optical element 30 can be pivoted to a retracted position, and the distance between the visual inspection image and the exit opening 10A is approximately 1 meter.

[0196] The first mirror 41 can then be pivoted to a second position (at 135° relative to the screen axis S). The light beam emitted by the screen 21 is then reflected by the first mirror 41 directly towards the beam splitter 26, which then reflects it towards the individual's eye. The distance between the visual inspection image and the exit aperture 10A is then approximately 40 centimeters (in the configuration of FIG. 8).

[0197] Thus, the visual inspection image can be displayed at three fixed distances from the exit opening of the device.

[0198] In a third embodiment of the vision measuring device 300, the vision test image can be viewed by an individual at three different optical distances.

[0199] The fourth embodiment is another simplified modification of the first embodiment. In this fourth embodiment, shown in Fig. 9, the screen is fixed. The screen axis S is in the vertical direction, and the first mirror 41 is removed. The second mirror 42 and the third mirror 43 are mounted so as to be slidable in the vertical direction along the second rail 52, similar to the first embodiment.

[0200] The light beam emitted by the screen 21 is emitted directly towards the second mirror 42, reflected by the second mirror 42 towards the third mirror 43, and then reflected by the third mirror 43 towards the optical element 30 in its operating position or towards the beam splitter 26 when the optical element 30 is in its retracted position.

[0201] The lens 31 here has an effective focal length of, for example, 686 mm, and the field of view of the screen 21 is approximately 11° along the horizontal axis. The maximum visual acuity determined is 16 / 10 at 2 pixels. The pixel size is, for example, approximately 63 microns.

[0202] With the lens in the operative position, the distance between the visual inspection image and the exit aperture 10A can be varied from 80 centimeters to infinity.

[0203] With the lens in the retracted position, the distance between the visual inspection image and the exit opening 10A can be varied between 40 centimeters and 95 centimeters.

[0204] In a fourth embodiment of the vision measuring device 400, the vision test image can be viewed by an individual at two different distance ranges.

[0205] In fact, whatever the embodiment considered, the translation of the screen and / or the rotation or translation of the mirrors and / or the movement of the optical elements of the clarity module along the optical path of the light emitted by the screen is preferably achieved automatically through a motorized system controlled by said electronic unit (not shown in the figures).

[0206] The electronic unit is programmed to command these movements based on the predetermined bending process step and parameters entered by the operator.

[0207] The clarity module is adapted to generate an image of an object at a variable distance relative to the individual's eye E. The image of the object is a real or virtual image of the test image displayed by the screen 21.

[0208] The individual's field of view is large enough to view the entire screen 21 .

[0209] The light beam exiting the clarity module 20A is ultimately reflected by the beam splitter 26 towards the test unit 10 and through the test unit 10 towards the individual's eye.

[0210] In scene module 20B, the light beam generated by additional screen 22 is reflected by beam splitter 26 toward additional mirror 24 (as shown, for example, by ray R1 in FIG. 1), reflected by additional mirror 24 toward beam splitter 26 (ray R2), and finally transmitted by beam splitter 26 toward the individual's eye E (ray R3).

[0211] The additional mirror 24 has a focal length that allows the individual using the vision measuring device to view the image produced by the additional screen 22 at a distance of more than 5 meters or more than 6 meters.

[0212] Therefore, in this embodiment, the elements of the scene module 20B are positioned so that the virtual image generated by the additional screen 22 of the scene module 20B is located at a distance relative to the individual's eyes, i.e., corresponding to the distance vision of the individual's eyes.

[0213] Thus, the beam splitter 26 not only reflects the light beam generated by the clarity module 20A, but also adds the light beam originally generated by the additional screen 22 of the scene module 20B in the same direction, i.e., allows the image generated by the clarity module 20A to be combined with another image generated by the screen of the scene module 20B. Finally, the overall image seen by the individual, generated by the display unit, includes the superimposed visual test image generated by the clarity module and the scene image generated by the scene module.

[0214] In the variant in which the additional screen includes an LED matrix and a light diffuser, a soft ambient light generated by the scenery module surrounds the visual test image generated by the clarity module.

[0215] The width of the additional screen 22 of the scene module 20B extends over almost the entire length of the beam splitter 26, thus making it possible to generate a light beam that is visible to an individual's eye E over a fairly wide angle, generally greater than 10°, preferably greater than 30°.

[0216] According to the invention, the light beam emitted by the screen 21 of the clarity module 20A is also visible to the individual's eye E over a fairly wide angle, generally an angle of 5° or more. In other words, the angular size of the vision test image measured looking from the exit aperture 10A is greater than 5°, for example comprised between 5° and 25°, more preferably between 8° and 15°, relative to the screen used for the visual acuity test, the latter image being surrounded by the image of an additional screen 22 having a wide field of view of 33° in the horizontal axis.

[0217] The novel visual acuity measuring device 100; 200; 300; 400 according to the present invention allows for easy assessment of an individual's visual performance at different distances from the vision test image.

[0218] Additionally, optical elements can be removed from the optical path to display the vision test image at a near viewing distance from the individual's eyes. This allows for a larger image size to be displayed for the vision test image under near viewing conditions. The larger image size allows for the display of text to be read and for the image to be more easily centered relative to the exit aperture of the device. For example, the vision test image has an angular size of 15° along the horizontal axis when displayed at a distance of 33 centimeters with the lens 31 in the retracted position.

[0219] Thus, subjective refraction testing using the refraction testing unit 10 can be performed with a selected set of targets positioned at different distances from the individual's eyes.

[0220] This subjective refraction test results in more accurate refraction measurements that may include measurements at infinity using embodiments that allow for continuous variation of the distance between the generated visual test image and the exit aperture.

[0221] While varying the distance between the visual inspection image and the exit opening 10A, the size of the target or any other object displayed by this screen 21 can be adjusted accordingly, this adjustment being controlled by the electronic unit.

[0222] The above-described visual acuity testing device is compact, but can simulate real-world conditions using an image generated by a scene module with a wide field of view, making it possible to conduct visual acuity tests using visual acuity test images that are close to realistic visual acuity conditions.

[0223] By using the clarity module 20A and the scene module 20B simultaneously, a high resolution visual target can be displayed in the center of an image with a wide field of view.

[0224] If the additional screen 22 of the scene module 20B is a video display, the test carried out using the vision measuring device can even simulate a moving environment, as would be found in a real situation.

[0225] In the example described here, the optical element 30 includes an optical lens 31 .

[0226] In the example described here, the optical element 30 is rotatable between the operating position and the retracted position. Alternatively, the optical element may be translatable between the operating position and the retracted position. The example described above may be implemented, for example, with an optical lens translatable between a first position in which the lens is positioned across the optical path and the optical axis of the lens is aligned with the primary direction, and a second position in which the lens is displaced from the optical path and the optical axis of the lens remains parallel to the primary direction.

[0227] In an alternative simplified embodiment of the present invention, the clarity module of the display unit does not include any reflective surfaces, but only a screen and optical elements, which may or may not be translatable along the screen axis.

[0228] Moreover, the relative positions and orientations of the optical components, particularly the reflective surfaces of the device, can be modified to obtain the same distance between the visual inspection image and the exit aperture.

[0229] In an alternative simplified embodiment of the present invention, there is no scenery module.

[0230] An advantage of the embodiment using an optical element with variable power, and of the embodiment using a movable screen 21 and without folding mirrors 41, 42, 43, in which the optical axis extends along a straight line between the optical element 30 and the screen 21, is that it presents the subject with images shown at variable distances with seamless transitions. This advantage is possible in the first case because the change in power of the adjustable lens is continuous, and in the second case because the displacement due to the translation of the screen 21 can also be continuous.

[0231] According to the present invention, the above-described visual acuity measuring device comprises the following steps: i) generating a visual test image for the individual's eye based on the test image, the visual test image being viewable through an exit opening of the visual acuity measuring device, e.g., a phoropter, through which the individual's eye can view the test visual image; ii) changing the state of the optical element (30) between the operative state and the inoperative state, thereby varying the variable distance between the visual inspection image and the exit aperture (10A); iii) it may be used to test the eyes of an individual, together with the step of evaluating the visual perception of the visual test image by at least one eye of the individual at different distances between the visual test image and the exit aperture.

[0232] In particular, step ii) may comprise varying the distance between the visual inspection image and the exit opening by moving an optical element between an operating position in which the optical element is positioned on the optical path of light emitted by the screen and exiting the device through the exit opening, and a retracted position in which the optical element remains out of the optical path.

[0233] Step ii) may alternatively comprise varying the variable power of the optical element between a non-zero value corresponding to said operating state and a zero value corresponding to said non-operating state, in which case the optical element is not moved, but remains in the optical path of the light.

[0234] Visual perception of a visual test image is assessed by asking the individual to characterize their perception of the visual test image, by stating whether they see or do not see it, or by recognizing or not recognizing a visual target, such as a letter. Visual perception can also be assessed, for example, by determining the delay required for an individual to recognize a visual target. Assessment of visual perception can be performed by any method known to those skilled in the art.

[0235] Furthermore, with fixed screen and optical element positions, the optical power of the lenses and / or the vision test image within the vision measurement device are varied depending on the individual's responses during the evaluation step.

Claims

1. A visual acuity measuring device (100; 200; 300; 400) for testing the eyes of an individual, comprising: a refraction test unit (10) having an optical system for providing different vision correction powers in the vicinity of the eye of the individual; and a display unit (20) adapted to generate a vision test image for the eye of the individual, the vision test image being visible through an exit opening (10A) of the test unit of the vision measuring device (100; 200; 300; 400), the display unit (20) comprising: a screen (21) adapted to display a test image used in generating said visual test image; At least one optical element (30) having an optical power; Including, The optical element (30) provides an operational state in which the optical element presents a non-zero refractive power that is positioned on the optical path of light emitted by the screen (21) and exiting the vision measuring device (100; 200; 300; 400) through the exit opening (10A), and a non-operational state in which the optical element does not introduce any refractive power on the optical path so that the vision test image is generated at a variable distance from the exit opening (10A), one or several reflective surfaces for bending the optical path of the light; The one or more reflective surfaces of the vision measuring device (100; 200; 300; 400) comprise a first mirror (41) that is rotatable between at least two positions to further change the variable distance.

2. The vision measuring device (100; 200; 300; 400) of claim 1, wherein the optical element (30) is movable between an operating position corresponding to the operating state in which the optical element (30) is positioned on the optical path of the light emitted by the screen (21) and exiting the device (100; 200; 300; 400) through the exit opening (10A), and a retracted position corresponding to the non-operating state in which the optical element (30) remains out of the optical path.

3. 2. The vision measuring device (100; 200; 300; 400) of claim 1, wherein the optical element remains positioned on the optical path of the light and has a variable refractive power that is variable between a non-zero value corresponding to the operating state and a zero value corresponding to the non-operating state.

4. The vision measuring device (100; 200; 300; 400) according to any one of claims 1 to 3, wherein the variable distance is included between a far vision distance and a near vision distance or an intermediate vision distance.

5. The vision measuring device (100; 200; 300; 400) according to any one of claims 1 to 4, wherein the optical element (30) is an optical lens (31).

6. 3. The vision measuring device (100; 200; 300; 400) according to claim 2, wherein the optical element (30) is rotatable and / or translatable between the operating position and the retracted position.

7. A vision measuring device (100; 200; 300; 400) as described in any one of claims 1 to 6, wherein the screen (21) is translatable along a reference axis between two positions corresponding to different distances between the generated visual test image and the exit opening (10A).

8. The vision measuring device (100; 200; 300; 400) of any one of claims 1 to 7, wherein the screen (21) is translatable along two orthogonal directions to center the screen (21) relative to the optical axis of the optical element (30).

9. The vision measuring device (100; 200; 300; 400) of claim 7, wherein the optical element (30) is an optical lens (31) in an operational state, and the relative position of the screen (21) and the optical lens (31) is adjustable so that the screen (21) is positioned at a distance from the optical element (30) equal to the rear focal length of the optical lens (31) measured along the optical axis (L) of the optical lens (31).

10. The visual acuity measuring device (100; 200; 300; 400) of any one of claims 1 to 9, wherein the visual test image includes the test image displayed by the screen (21) without the influence of the optical element (30), whether or not reflected by a reflective surface of the device, or an image of the test image projected by the optical element (30), whether or not reflected by a reflective surface of the device.

11. A vision measuring device (100; 200; 300; 400) as described in any one of claims 1 to 10, wherein the relative positions of the screen (21), the optical element (30) and the exit opening (10A) are made to be changed in order to continuously change the distance between the visual test image and the exit opening (10A) in one or several optical distance ranges included between infinity and near vision distance.

12. A vision measuring device (100; 200; 300; 400) as described in any one of claims 1 to 11, wherein at least one reflective surface is arranged within the device so as to direct the optical path of the light emitted by the screen (21) towards the exit opening (10A).

13. The vision measuring device (100; 200; 300; 400) according to any one of claims 1 to 12, wherein the at least one reflecting surface is translationally and / or rotationally movable between at least two positions.

14. A vision measuring device (100; 200; 300; 400) as described in any one of claims 1 to 13, wherein the at least one reflective surface is translated and / or rotated to a position where the at least one reflective surface directs the light emitted by the screen (21) towards the exit opening (10A) when the optical element remains out of the optical path.

15. 2. The vision measuring device (100; 200; 300; 400) according to claim 1, wherein the first mirror (41) is rotationally movable only when the optical element (30) is in the inoperative state.

16. 2. The vision measuring device (100; 200; 300; 400) of claim 1, wherein the second mirror (42) and the third mirror (43) are slidably movable to generate the vision test image at variable distances from the exit opening (10A).

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