Method for automatically centring an ophthalmic lens
By using image processing technology to determine the optical center of the lens, the problem of centering difficulties under complex centering marks is solved, achieving precise centering and obstruction of the lens, and ensuring the correct installation of the lens in the eyeglass frame.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ESSILOR INTERNATIONAL(COMPAGNIE GENERALE D OPTIQUE)
- Filing Date
- 2022-03-07
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies make it difficult to accurately center lenses, especially when the centering marks on the lens have complex and varied shapes, which makes centering operations difficult and makes it impossible to effectively place obstructing accessories.
By acquiring an image of the lens, the processing unit determines the positions of at least three centering markers, infers the optical center of the lens, and uses the least squares fitting method to locate and scale the regular geometry. Combined with the optical axis orientation of the lens, precise centering of the lens is achieved.
It achieves accurate lens centering, avoids manual operation and human error, ensures the correct placement of blocking accessories, and supports subsequent edging and installation processes.
Smart Images
Figure CN116963869B_ABST
Abstract
Description
Technical Field
[0001] This invention generally relates to the field of eyeglasses.
[0002] More specifically, the present invention relates to a method for centering an ophthalmic lens, the method comprising the following steps:
[0003] - Position the ophthalmic lens on a component (holder) of the centering device.
[0004] - Acquire at least one image of the ophthalmic lens using an image sensor, and
[0005] - The image is processed by a processing unit to locate the optical center of the ophthalmic lens. Background Technology
[0006] The technical aspect of an optician's work involves fitting a pair of eyeglass lenses into a frame chosen by the customer. This technical aspect can be divided into four main procedures:
[0007] - Obtain the shape of the lens rims of the eyeglass frames selected by the customer.
[0008] - Centering each ophthalmic lens involves determining the lens's reference frame using centering marks set on the lens, and then appropriately positioning the previously obtained lens rim profile within the lens's reference frame. This ensures that once the lens is edged to this profile and then installed in the lens frame, it is correctly positioned relative to the customer's corresponding eye and best fulfills the optical function designed for this purpose.
[0009] - Each lens is blocked, including attaching a blocking accessory to the lens, so that the lens can be easily removed from the centering station and then joined in the edging station without losing the reference frame.
[0010] - Grind the edges of each lens, including machining the lens into the previously centered profile.
[0011] Here, the centering and blocking operations are of particular interest.
[0012] These procedures are typically performed by opticians using centering-blocking devices.
[0013] Such devices are typically configured in the same way to have: a device for holding the ophthalmic lens, an optical device for centering the ophthalmic lens, and a blocking device for placing a blocking accessory on the lens.
[0014] The applicant has sold an exemplary centering-blocking device under the reference name "Mr. Blue". In this device, the optical centering mechanism includes a camera adapted to acquire images of a lens that display centering marks on the lens, thereby allowing the device to center the lens. The blocking mechanism includes an arm capable of placing a blocking accessory on the lens at a position inferred from the centering operation.
[0015] Lens centering marks typically include a dot or cross located on the optical point of the lens.
[0016] However, the shape of the lens centering marks can sometimes make centering operations difficult. For example, the lens marks may be rounded micro-engraved, numerous, and distributed along concentric circles.
[0017] In the case of such lens markings, because the optical points of the lens are not marked, the equipment has difficulty centering the lens and therefore cannot place the blocking accessory on these optical points. Summary of the Invention
[0018] In this context, the present invention provides a method as disclosed in the description, which is particularly suitable for centering ophthalmic lenses comprising (e.g., distributed along at least one regular geometry) a plurality of distinct centering marks, wherein the processing steps include:
[0019] - For at least three of the centering markers, determine the position of at least one representation point for each centering marker, and
[0020] - This leads to the deduction of the position of the optical center of the ophthalmic lens.
[0021] Because of this invention, centering is performed by considering not only one centering mark but several centering marks, which makes it possible to accurately determine the position of the optical center of the lens. Furthermore, this method avoids manual operation and operator error.
[0022] Other preferred features of the present invention are as follows:
[0023] - The characterization point is the geometric center of the centering mark.
[0024] - The position of the optical center of the ophthalmic lens is determined based on the position of the characterizing points of all the centering marks on the ophthalmic lens.
[0025] - The distinguished centering markers are distributed along a virtual regular geometry.
[0026] The processing steps include positioning a determined regular geometric shape on the acquired image such that the determined regular geometric shape passes through the characterization points of the at least three centering markers, and inferring the position of the optical center based on the position of the determined regular geometric shape.
[0027] The processing steps further include scaling the determined regular geometry so that the determined regular geometry passes through the representation points of the at least three centering markers.
[0028] The positioning of the determined regular geometry, and scaling of the determined regular geometry if necessary, are performed using the least squares fitting method.
[0029] The shape of the determined regular geometric figure is determined manually or automatically by the processing unit based on the acquired image.
[0030] - The determined regular geometry does not exhibit rotational symmetry, and the method includes the step of inferring the optical axis of the lens based on the orientation of the determined regular geometry.
[0031] - The virtual regular geometric shape is a polygon, or a closed curve, or a combination of line segments and curves.
[0032] - The virtual regular geometric shape is a circle, rectangle, rhombus, or hexagon.
[0033] - The centering markers are distributed along at least two virtual regular geometric figures that are coaxial and of the same type.
[0034] The present invention also relates to a process for centering and blocking ophthalmic lenses, the process comprising:
[0035] - A first operation of centering the ophthalmic lens according to the method defined above, and
[0036] - A second operation to block the ophthalmic lens by means of a blocking accessory placed on the ophthalmic lens in a blocking position.
[0037] In the first embodiment, the blocking position is the position of the optical center of the ophthalmic lens.
[0038] In the second embodiment, the blocking position is determined relative to the optical center and sent to the edging machine in consideration of the edging of the ophthalmic lens.
[0039] Before placing the blocking accessory onto the ophthalmic lens, the position of the blocking accessory relative to the ophthalmic lens is preferably automatically adjusted, while the lens remains stationary relative to the component (lens holder).
[0040] In this variation, the position of the ophthalmic lens relative to the component is manually adjusted.
[0041] The present invention also relates to a centering device, the centering device comprising:
[0042] -frame,
[0043] - A component mounted on a rack (holder) suitable for receiving ophthalmic lenses.
[0044] - A centering device mounted on a rack, the centering device including an image sensor for acquiring an image of the ophthalmic lens when it is received on a holder, and
[0045] - A processing unit adapted to perform the method or process. Attached Figure Description
[0046] The following description, with reference to the accompanying drawings and by way of non-limiting examples, makes clear the scope of the invention and the ways in which it may be practiced.
[0047] In the attached diagram:
[0048] - Figure 1 This is a schematic perspective view of a first embodiment of the centering and blocking device according to the present invention.
[0049] - Figure 2 yes Figure 1 A schematic side view of the centering device of the centering and blocking equipment shown.
[0050] - Figure 3 It is necessary to rely on Figure 1 The front view of a first example of a lens centered using a centering and blocking device is shown.
[0051] - Figure 4 yes Figure 3 The view of the lens shows two defined, regular geometric shapes.
[0052] - Figure 5 It is necessary to rely on Figure 1 A front view of a second example of a lens used for centering and blocking devices, as shown.
[0053] - Figure 6 This is a schematic perspective view of a second embodiment of the centering and blocking device according to the present invention. Detailed Implementation
[0054] Figure 1 A first embodiment of an optical machine (hereinafter referred to as "centering and blocking device 100") for preparing an ophthalmic lens in the case of an edged view of the ophthalmic lens 10 is shown.
[0055] Therefore, this device is used to center and block ophthalmic lenses 10 that are to be mounted on eyeglass frames.
[0056] When the shape of the contour that must be followed to cut the lens is known, the goal of the centering operation is to identify the reference frame of the ophthalmic lens 10 and determine the position that the contour is intended to occupy in this reference frame so that once the lens is cut in accordance with this contour and then mounted on the eyeglass frame, the lens is positioned relative to the individual's corresponding eye in a suitable centered manner.
[0057] The objective of the blocking operation is to place the blocking attachment 150 onto the ophthalmic lens 10. On the one hand, the blocking attachment can more easily grip the ophthalmic lens 10 so that it can be transferred from the centering and blocking device 100 to the cutting unit (hereinafter referred to as the "edge grinding machine"). On the other hand, the blocking attachment can provide a stable reference mark to indicate the position of the lens's reference system after the lens has been transferred.
[0058] Figure 1 The centering-blocking device 100 shown is automatic, in this sense because the operation of searching for the position of the lens reference frame is performed automatically without the assistance of an optician.
[0059] It should be noted that in the following text, at least the point through the lens ( Figure 4 The reference frame is defined by the position of the optical center P1 shown, and possibly by the axis ( Figure 5 The orientation of the optical axis A3 of the lens is used to define the reference frame.
[0060] The device can have several shapes.
[0061] In the illustrated embodiment, the centering and blocking device 100 includes:
[0062] -Rack 101,
[0063] - Operating station 102, which is fixed to frame 101 on a horizontal plane, and includes holder 103 for holding the blocking attachment 150.
[0064] - Centering device 110 for centering the lens (see Figure 2 The device is fixed to the frame 101 and includes at least an image sensor 111 for acquiring images of the lens.
[0065] - A blocking device 120 for placing the blocking accessory 150 on the ophthalmic lens 10, said device being mounted to be movable on the frame 101, and
[0066] - Processing unit 130 for controlling the centering device and the blocking device (see...) Figure 2 ).
[0067] The operating station 102 includes a transparent flat support plate 104, at the center of which a holder 106 for holding the ophthalmic lens 10 is provided. Here, the holder is a rod-shaped member with a widened head to support the lens. In variations, the holder 106 may have different shapes, or it may be formed from the support plate 104.
[0068] The blocking device 120 includes an operating arm 121, which includes a carrier capable of gripping the blocking attachment 150 and placing the blocking attachment on the front of the ophthalmic lens 10 placed on a transparent flat support plate 104.
[0069] The manipulator 121 is self-driven and has four degrees of freedom. Therefore, the manipulator is capable of translating along the vertical axis A1 to rise or fall in the direction of the planar support plate 104, and is capable of rotating about this axis A1 to move away from or towards the planar support plate 104. The carrier (not visible) of the manipulator is capable of radial translation relative to this axis A1 and is capable of rotating about an axis parallel to this axis A1 (to adjust the orientation of the blocking attachment relative to the arm).
[0070] The device used to center the ophthalmic lens 10 is itself designed to determine the position of the reference frame of the ophthalmic lens 10.
[0071] like Figure 2 As shown, the centering device 110 includes a means for illuminating a lens placed on the planar support plate 104 on one side and an image sensor means for acquiring the emitted light on the other side.
[0072] The lighting device includes a light source 112 and a reflector 114 tilted at 45°, the light source emitting a light beam and the reflector reflecting the light beam toward the lens.
[0073] The image sensor device includes an image sensor (here, camera 111) and a reflector 113 tilted at 45° that reflects the light beam toward camera 111.
[0074] The optical axis A2 of the centering device 110 is defined as the axis of the light beam passing through the ophthalmic lens 10.
[0075] The processing unit 130 is programmed to center and block the ophthalmic lens 10.
[0076] Therefore, the processing unit includes a central processing unit (CPU), memory, and input / output components.
[0077] Because of its memory, the processing unit stores information used in the processes described below. In particular, the memory stores computer applications, which consist of computer programs including instructions that, when executed, allow the processing unit to implement the methods described below.
[0078] The processing unit 130 is connected to the centering device 110 and the blocking device 120.
[0079] In a preferred embodiment, the processing unit is also connected to a human-machine interface (here, a touchscreen) to allow the optician to input data that can be used to center the lens.
[0080] Figure 3 The image shows an ophthalmic lens 10 to be edged. This lens has two optical surfaces (i.e., a convex front and a concave back) and an edge 11, the shape of which is initially rounded. The shapes of the front and back of this ophthalmic lens 10 are designed to give the lens optical properties that allow for the correction of a client's vision defects.
[0081] Here, the ophthalmic lens 10 includes a first optical correction and a second optical correction, the first optical correction being used to provide the wearer with corrected vision at a defined distance, and the second optical correction being used to alter the natural evolution of myopia.
[0082] In the example, the first optical correction includes a spherical power that provides the wearer with corrective vision for distance viewing (for observing objects located more than 6 meters away). In a variant, this first optical correction may also include cylindrical and / or prismatic power. In this variant, the lens includes an optical axis that defines the orientation of the cylindrical and / or prismatic power.
[0083] In the example, the optical center of the lens is defined as the point on the lens where light rays will not deviate when passing through it.
[0084] In the first embodiment, it can be assumed that the centering point of the ophthalmic lens 10 (i.e., the point where the blocking accessory must be placed) is formed by the optical center P1.
[0085] In the second embodiment, the centering point is formed by the geometric center (referred to as the "frame center") of the virtual rectangular frame along the contour of the lens edge being ground.
[0086] In both embodiments, the centering and blocking device 1 should notify the edge grinding device of the point where the blocking attachment is positioned.
[0087] The second optical correction provides additional optical features. This correction is specifically designed to limit or prevent the progression of myopia.
[0088] In this example, for this purpose, the ophthalmic lens 10 includes microlenses. Such an ophthalmic lens is described in document WO 2019166654.
[0089] The ophthalmic lens 10 is provided with distinct centering marks 12, thereby allowing for the positioning of the reference frame of the ophthalmic lens. These centering marks are distinct in that they have different positions, making their shapes clearly distinguishable from each other.
[0090] These markings can take the form of temporary markings printed with ink and / or permanent markings engraved in the lens (known as micro-engraving).
[0091] Temporary markings typically allow for the proper positioning of the lens's optical reference frame before it is installed in the eyeglass frame, while permanent markings allow for the identification of the nature and characteristics of ophthalmic lenses and allow for the identification or reconstruction of the lens's exact position after the temporary markings have been removed.
[0092] Here, the ophthalmic lens 10 only has a permanent mark for determining the position of the centering point P1 of the lens.
[0093] like Figure 3 As shown, in this embodiment, each of these micro-engraved marks 12 is rounded, there are a large number of these micro-engraved marks, and these micro-engraved marks are distributed along a regular geometric pattern around the centering point P1 of the ophthalmic lens 10.
[0094] More generally, the centering marks 12 are distributed along one or more regular geometric shapes.
[0095] Here, regular geometric figures are defined as figures whose shapes are predetermined and can be found on the image of the lens.
[0096] This shape is preferably closed. It is preferably a polygon, or a closed curve (circle, ellipse, etc.), or a combination of line segments and curves.
[0097] exist Figure 3 In the example, these centering marks are distributed along two virtual coaxial circles 13, 14 (represented by dashed lines because these two virtual coaxial circles are not marked on the lens). Each virtual circle includes more than ten marks 12. In a preferred embodiment, the centering marks 12 are distributed along more than three coaxial virtual circles.
[0098] exist Figure 5 In the variant shown, centering marks 12 are distributed along two coaxial virtual rectangles. In this variant, when the lens has cylindrical and / or prismatic power, the longest side of these rectangles is oriented parallel to the optical axis of the lens.
[0099] Other variations can be considered. For example, the centering mark 12 can be distributed along rhombuses, squares, stars, pentagons, hexagons, etc.
[0100] The centering marks 12 of each individual regular geometric shape have the same shape, that is, circular shapes with the same diameter. Here, all centering marks 12 have the same diameter. This diameter is less than 1 mm.
[0101] In the disclosed embodiments, these centering marks 12 are formed by the contours of microlenses, which are engraved in one of the optical surfaces of the lens to satisfy a second optical correction.
[0102] The aim here is to automatically center and block the ophthalmic lens 10.
[0103] Therefore, during the previous step, the ophthalmic lens 10 is positioned on the holder 106 manually or automatically. Here, the optician places the ophthalmic lens 10 on the upper end of the holder 106 such that the convex front faces away from the holder 106.
[0104] Then, during the first step, the processing unit 130 is programmed to acquire an image of the lens supported by the holder 106 by means of the camera 111.
[0105] Because of the centering device 110 of the device, the centering mark 12 of the ophthalmic lens 10 is visible in this image.
[0106] During the second step, the image is processed to locate the outline of each centering mark 12.
[0107] Based on these contours, the processing unit 130 determines the position of the characterization point P12 for at least three (preferably for all detected characterization marks) of the detected centering marks 12.
[0108] The characterization point P12 is defined as a point that can be distinguished among all the points on the marker. This point characterizes the position of the centering marker 12. For example, this point could be the center of the marker, the centroid of the marker, or one of the corners of the marker…
[0109] In a preferred embodiment, this characterization point P12 is the geometric center of the centering mark 12. Since each centering mark 12 is circular, the characterization point P12 is the center of the circle.
[0110] At this step, processing unit 130 determines whether some of the centering marks are distributed along a closed contour. In a variant, this operation can be skipped if the optician fills in a field on the touchscreen indicating that the centering marks 12 are distributed along a circle.
[0111] In the example, when a centering mark is detected to be distributed along at least one circle, the processing unit 130 detects the number of coaxial circles along which the centering mark 12 is distributed. Here, two circles are detected.
[0112] Then, the processing unit 130 virtually positions the two defined regular geometric shapes 23 and 24 on the acquired image and scales them, so that these defined regular geometric shapes 23 and 24 pass through the representation point P12 of the centering mark 12 (see...). Figure 4 ).
[0113] Here, geometric figures 23 and 24 are "determined" in this sense because their type (circle...) is already known at this step. This type is the same as that of the virtual figures 13 and 14.
[0114] In the disclosed embodiment, since the processing unit has detected that the centering marks are distributed along two virtual circles, the specific regular geometric figures 23 and 24 to be located are also two circles.
[0115] In the variant, the types of geometric figures 23 and 24 can be manually selected, or they can always be the same (processing unit 130 can be programmed to always position the same type of geometric figures 23 and 24, such as circles).
[0116] These operations of positioning and scaling the defined regular geometric figures 23 and 24 can be performed in various ways.
[0117] For example, the processing unit can attempt to gradually superimpose each circle onto the maximum representation point P12 by trying different positions and diameters until the optimal position is reached.
[0118] However, in a preferred embodiment, the processing unit 130 begins by defining a plurality of sets of centering marks 12, each set of centering marks 12 being distributed along the same regular geometric patterns 13, 14. Here, two sets of centering marks are defined (see...). Figure 3 ).
[0119] Then, for each set of centering marks 12, the processing unit 130 uses the least squares fitting method to locate and scale the corresponding determined regular geometric figures 23 and 24, so as to minimize the sum of the distances between the figure and the representation point P12 of the centering mark 12.
[0120] During the third step, the processing unit 130 determines the position of the center of these determined regular geometric shapes 23, 24.
[0121] exist Figure 4 In the example, processing unit 130 determines the position of the center of the two circles. Figure 5In the example, processing unit 130 determines the position of the center of the two rectangles.
[0122] Then, the processing unit 130 positions the optical center P1 of the ophthalmic lens 10 at the average position of these centers.
[0123] During the fourth step, if the lens includes an optical axis A3 that defines the cylinder power and / or prism power... Figure 5 If the processing unit 130 determines the orientation of at least one of the longest sides of these defined regular geometric figures 23 and 24, then the processing unit 130 determines the orientation of at least one of the longest sides.
[0124] Then, the orientation of the optical axis A3 is inferred based on the orientation of the longest side.
[0125] In the variant, this orientation can be inferred from the orientation of each longest side of each defined regular geometry 23, 24 (by calculating the average of these orientations).
[0126] Finally, the final step involves blocking the ophthalmic lens 10 by means of the blocking accessory 150.
[0127] Therefore, the optician mounts the blocking accessory 150 on the vertical axis of the retainer 103.
[0128] Then, the processing unit 130 moves the blocking arm 121 to grasp the blocking attachment 150 and place the blocking attachment on the front of the lens.
[0129] In the first embodiment, the blocking attachment 150 is positioned on the optical center P1 of the ophthalmic lens 10.
[0130] In a variant, the blocking attachment 150 is placed on another centering point. In this variant, the position of this centering point relative to the optical center P1 is determined, and this position is sent to the edging machine in consideration of the edging of the ophthalmic lens 10.
[0131] This invention is by no means limited to the embodiments described and shown.
[0132] For example, the centering process described above can be applied not only to blocking and edge grinding, but also to stamping or engraving lenses.
[0133] In the first variant, it can be assumed that the diameters of the circles 13 and 14 along which the centering mark 12 is distributed are well known, making it unnecessary to scale the regular geometric figures 23 and 24.
[0134] However, this variant is not preferred for the following reasons.
[0135] The size of centering mark 12 and the sizes of circles 13 and 14 may change as the proportions change with the modification of the lens power; therefore, the diameter of the circle may change depending on the spherical power of the lens.
[0136] In addition, different brands of lenses may display centering marks of different sizes, which is why it is advantageous to make the diameter of regular geometric shapes 23 and 24 scalable.
[0137] In another variation, the characterization point (P12) of each centering mark can be formed by the centroid of the mark or a corner of the mark (e.g., if the mark is a square or a triangle).
[0138] In another variation, the optical center (P1) can be calculated as the point whose distance from the characterization point has the smallest standard deviation.
[0139] Figure 6 A second embodiment of the centering and blocking device 200 is shown.
[0140] In this embodiment, the device is designed to allow for manual blocking operations.
[0141] For this purpose, the centering and blocking device 200 includes at least:
[0142] -Rack 210,
[0143] - Holder 220, which is mounted on frame 210 and adapted to receive ophthalmic lenses.
[0144] - A blocking device 230, which is mounted on the frame 210 and adapted to receive a blocking accessory 290, and
[0145] - Centering device 240, which is mounted on frame 210, includes a sighting objective lens, through which the optical reference frame of the ophthalmic lens can be observed.
[0146] In the illustrated embodiment, the blocking device 230 is fixedly mounted on the frame 210, and the retainer 220 is movably mounted on the frame 210.
[0147] The frame 210 includes a dome 211. This dome 211 has sidewalls, the top surface of which has a large circular opening 212 centered on a main axis A4, which is vertical. The frame also includes a bottom located on a horizontal plane and enclosing the rear portion of the sidewalls. Finally, the frame includes a false bottom 214 at an intermediate height.
[0148] The false bottom 214 can be seen through the large circular opening 212. The false bottom has a circular hole at its center centered on the main axis A4.
[0149] The blocking device 230 includes a vertical shaft centered on the main axis A4. The lower end of this vertical shaft is fixed to the frame, and the free upper end is used to accommodate the blocking attachment 290.
[0150] The retainer 220 is a transparent vertical tube that is mounted on the frame 210 so that it can slide along the main axis A4.
[0151] The upper end 222 of the retainer 220 is circular and extends in a horizontal plane to accommodate ophthalmic lenses.
[0152] This retainer 220 is more precisely installed so that it can move between the following two positions:
[0153] - Centering position, in which the ophthalmic lens resting on the upper end 222 of the holder 220 is located at a certain distance away from the blocking accessory 290, and
[0154] -Blocking position, in which the ophthalmic lens support rests against the blocking attachment 290.
[0155] An elastic element (suitable for automatically resetting the retainer 220 to the centering position) is disposed inside the dome 211.
[0156] The centering device 240 includes a device 250 for illuminating an ophthalmic lens and a device 260 for observing the ophthalmic lens illuminated by the illumination device 250.
[0157] The illumination device 250 consists of light-emitting diodes regularly distributed around the entire holder 220 to generate grazing incident light on the optical surface of the lens placed on the holder 220 (here, on the convex front surface engraved with centering marks).
[0158] The observation device 260 includes a reflector 263 tilted at 45° relative to the main axis A4, which allows the image from the ophthalmic lens to be redirected toward the objective lens 261 of the digital camera 262. This reflector 263 allows for a more compact centering-blocking device 200.
[0159] Therefore, the digital camera 262 was designed to acquire an image of the ophthalmic lens and transmit that image to a viewing screen 270 oriented toward the optician's face.
[0160] Therefore, opticians can observe the images of the ophthalmic lenses in real time on this viewing screen 270.
[0161] The centering-blocking device 200 also includes a processing unit (invisible) that is programmed to assist opticians in centering and blocking ophthalmic lenses.
[0162] Therefore, the processing unit includes a central processing unit (CPU), memory, and input / output components. Due to its memory, the processing unit stores information used in the processes described below.
[0163] In this second embodiment, the ophthalmic lens is intended to be automatically centered, but is manually blocked.
[0164] Therefore, during the previous step, the blocking attachment 290 is accommodated on the upper end of the shaft 230, and the ophthalmic lens is manually positioned on the retainer 220.
[0165] Then, during the first step, the processing unit is programmed to acquire an image of the lens supported by the holder 220 by means of the camera 262.
[0166] During the second step, this image is processed to locate the outline of each lens centering mark.
[0167] During the third step, the processing unit detects and locates the centering marks along the circles where they are distributed.
[0168] During the fourth step, the processing unit determines the location of the center of these circles.
[0169] These four steps are performed in the same way as those steps described above (in the first embodiment of the present invention).
[0170] Then, during the fifth step, the processing unit connected to the observation screen 70 displays two datum lines superimposed on the image acquired by the camera 262.
[0171] The first marking indicates the center of the obstruction attachment 290.
[0172] The second punctuation mark indicates the center of the detected circle.
[0173] Because of these markings, the optician can manually adjust the position of the ophthalmic lens relative to the holder 220 so that the second marking is exactly on the first marking.
[0174] It should be noted that during the fifth step, the first four steps are performed in a loop so that the position of the second mark can be corrected when the optician moves the lens.
[0175] When the two markings overlap, the holder 220 is manually moved from its centering position to its blocking position, so that the ophthalmic lens is supported and glued against the blocking attachment 290.
Claims
1. A method for centering an ophthalmic lens (10), the method comprising the following steps: - Position the ophthalmic lens (10) on part (106) of the centering device (100), - Acquire at least one image of the ophthalmic lens (10) using an image sensor (111), and - The image is processed by the processing unit (130) to locate the position of the optical center (P1) of the ophthalmic lens (10). The ophthalmic lens (10) is characterized by comprising a plurality of distinct centering marks (12) distributed along a virtual regular geometric pattern (13, 14), and the step of processing the image by means of the processing unit (130) includes: - For at least three of the centering marks (12), determine the position of at least one characterization point (P12) for each centering mark (12). - Position the determined regular geometric figures (23, 24) on the acquired image such that the determined regular geometric figures (23, 24) pass through the representation points (P12) of the at least three centering marks (12), and - The position of the optical center (P1) of the ophthalmic lens (10) is inferred from the position of the determined regular geometric figures (23, 24).
2. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The characterization point (P12) is the geometric center of the centering mark (12).
3. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The position of the optical center (P1) of the ophthalmic lens (10) is determined based on the position of the character point (P12) of all the centering marks (12) of the ophthalmic lens (10).
4. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The processing steps further include scaling the determined regular geometry (23, 24) such that the determined regular geometry (23, 24) passes through the characterization points (P12) of the at least three centering marks (12).
5. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The positioning of the determined regular geometry, and scaling of the determined regular geometry if necessary, are performed using the least squares fitting method.
6. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The shape of the determined regular geometric figure (23, 24) is determined manually or automatically by the processing unit (130) based on the acquired image.
7. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The determined regular geometric figures (23, 24) do not exhibit rotational symmetry, and the method includes the step of inferring the optical axis (A3) of the lens based on the orientation of the determined regular geometric figures (23, 24).
8. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The virtual regular geometric figures (13, 14) are polygons, or closed curves, or combinations of line segments and curves.
9. The method for centering an ophthalmic lens (10) according to claim 8, wherein, The virtual regular geometric shapes (13, 14) are circles, rectangles, rhombuses, or hexagons.
10. The method for centering an ophthalmic lens (10) according to claim 1, wherein, The centering marker (110) is distributed along at least two virtual regular geometric figures (13, 14), which are coaxial and of the same type.
11. A process for centering and blocking an ophthalmic lens (10), the process comprising: - A first operation for centering the ophthalmic lens (10) according to any one of claims 1 to 10, and - A second operation to block the ophthalmic lens (10) by means of a blocking attachment (150) placed on the ophthalmic lens (10) in a blocking position.
12. The process according to claim 11, wherein, The blocking position is: - The position of the optical center (P1) of the ophthalmic lens (10), or - Another location, the blocking position is determined relative to the optical center (P1) and sent to the edging machine in view of the edging of the ophthalmic lens (10).
13. The process according to claim 11, wherein, Before placing the blocking attachment (150) onto the ophthalmic lens (10): - Automatically adjust the position of the blocking accessory (150) relative to the ophthalmic lens (10) while the lens remains stationary relative to the part (106), or - Manually adjust the position of the ophthalmic lens (10) relative to the part (106).
14. A centering device (100), comprising: - Rack (101) - A component (106) mounted on the frame (101), the component being adapted to receive an ophthalmic lens (10), and - A centering device (110) mounted on the frame (101), the centering device including an image sensor (111) for acquiring an image of the ophthalmic lens (10) when it is received on the part (106). The centering device is characterized in that it further includes a processing unit (130) adapted to perform the method according to any one of claims 1 to 10, or the process according to any one of claims 11 to 13.