Method and device for checking a marking on at least one spectacle lens

Abstract

The invention relates to a method for checking an arrangement of a marking (130) on at least one spectacle lens (100) having functional engravings (110a, 110b), in which method the spectacle lens (100) is placed on a multi-point support having a plurality of support points (120). Engraving positions of the functional engravings (110a, 110b) of the spectacle lens (100) placed on the multi-point support are recorded. A spectacle lens position of the spectacle lens (100) placed in this way is determined on the basis of the recorded engraving positions and by taking into account point positions of the support points (120) of the multi-point support. A marking position of the marking (130) on the spectacle lens (100) is determined and checked depending on the determined spectacle lens position.

Description

[0001]Applicant: Rodenstock GmbH Our reference: R 3370WO - hb / mu Method and device for checking a stamp on at least one spectacle lens The invention relates to methods and devices for checking the arrangement of a stamp on at least one spectacle lens with functional engravings. When grinding in spectacle lenses, an optician can use reference points on the spectacle lens as a guide. Before grinding in, spectacle lenses normally have a round, non-round, or elliptical shape. During grinding in, the spectacle lens is made to fit a selected frame and centered taking the reference points into account. During centering, the spectacle lens is aligned so that it is correctly positioned in the frame to produce an intended optical effect with regard to the eyes of the wearer. In particular, a centering point can be used as one of the reference points on the spectacle lens.Reference points on the lens can be marked by permanent functional engravings and / or by a stamp that can be removed after centering. The stamp can, for example, include the centering point and, depending on the type of lens, also a prism reference point and / or a near reference point. The functional engravings are usually not removable and remain on the lens. In particular, the functional engravings can include a point nasal and temporal to the centering point. Some of these reference points are defined in relevant standards, e.g. DIN EN ISO 13666, DIN 58208 and DIN EN ISO 21987. The functional engravings can, for example, be applied to the back of the lens while the lens is still blocked, whereby the optically relevant reference points are still precisely known when the lens is blocked. For this reason, the functional engravings can usually be positioned relatively well aligned on the lens.However, this does not necessarily apply to the positioning of the stamp. The stamp is often applied to the front of the lens, where the lens is blocked, for example, when the optically corrective back of the lens has been formed. For this reason, the stamp is usually only applied to the lens after the functional engravings have been made. As part of quality control, the arrangement of the stamp, and in particular its position relative to the functional engravings, can be checked. For this purpose, the stamp can be checked by stamping machines themselves. In this case, the positions of the stamp and the functional engravings are viewed from the convex side of the lens, which can result in inaccuracies due to the parallax effect, particularly with lenses with a high power and / or decentration and / or tilting in the lens holder.Such quality control can be performed manually or manually with the assistance of an inspection device, into which the lens to be inspected is manually inserted by an operator. The target positions of the functional engravings can initially be displayed in a camera image on a screen. The operator must then insert the lens into the inspection device and align it there so that the functional engravings are positioned at the target positions displayed on the screen. Since the functional engravings cannot usually be aligned 100% at the target positions, e.g., due to manufacturing inaccuracies, this alignment process is laborious, error-prone, and / or inaccurate.Once the lens has been aligned in the inspection device, the position of the stamp, in particular the centering point marked by a centering cross, and / or the axial position of stamp lines can be subjected to a subjective target-actual check. Manually aligning the lens based on the displayed target positions of the functional engravings is time-consuming for the operator. Furthermore, the inspection process is prone to errors, as, for example, functional engravings often cannot be aligned 100% to their target positions, leaving some leeway in the alignment. Furthermore, the final assessment of the stamp position is subjective and dependent on the operator and therefore difficult to qualify and / or document.Against this background, the object of the invention is therefore to improve the verification of the arrangement of the stamp on a spectacle lens, in particular to make the verification more efficient and / or reliable. This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims. One aspect relates to a method for checking an arrangement of a stamp on at least one spectacle lens with functional engravings. In this case, the spectacle lens is placed on a multi-point support with several support points. The engraving positions of the functional engravings of the spectacle lens placed on the multi-point support are recorded. A spectacle lens position of the spectacle lens placed in this way is determined on the basis of the recorded engraving positions and taking into account point positions of the support points of the multi-point support.Furthermore, the stamp position of the stamp on the lens is checked depending on the determined lens position. The lens can be designed as a single-vision or progressive lens, e.g., as an ophthalmic lens. The lens can be designed, for example, as a round, elliptical, non-round, or as a ground lens. The lens has the functional engravings, which can include at least one functional engraving arranged nasally and one temporally from the centering point. The functional engravings can be designed as a component of permanent engravings on the lens, which cannot normally be erased from the lens. The permanent engravings can include further markings, e.g., a brand engraving, an order code, a base curve, and / or a refractive index. Depending on the lens type, the permanent engravings can also, for example,an addition, a position of a distance design point and / or a position of a near design point. The permanent engravings and / or the functional engravings can be arranged, for example, on the back of the lens, which can be concave, for example, and / or can be arranged facing the eyes of a wearer when in use. The lens also has the stamp, which can have at least one marking of the centering point. The centering point can be marked by the stamp, for example, by means of a cross, the so-called centering cross. Depending on the specifications of the lens manufacturer, the position of the centering cross and the centering point can deviate slightly from one another. The centering cross can, for example, be arranged between the functional engravings, in particular approximately centrally between the nasal and temporal functional engravings. The stamp can be affixed to the lens in an erasable manner. The stamp can include further markings, e.g.(in the wearing position) horizontal lines nasal and temporal from the centering cross, a prism reference point and / or a near reference point. The stamp can be arranged, for example, on the front of the spectacle lens, which can be convex, for example, and / or arranged facing away from the wearer's eyes when in the wearing position. The spectacle lens can be placed on the multi-point support either with its front or its back. The spectacle lens can be placed on the multi-point support with its convex front side, for example, facing downwards. In this case, its functional engravings usually point upwards, as they are usually applied to the back of the lens. This means that the engraving positions can be recorded unhindered from above, for example, without having to be viewed and / or recorded through the lens.The multi-point support has a plurality of approximately point-shaped support points on which the spectacle lens is securely mounted. For example, the multi-point support can have three or four support points on which the spectacle lens rests securely. Alternatively, the multi-point support can also be ring-shaped, wherein the multi-point support has a plurality of support points. The side of the spectacle lens placed on the multi-point support preferably rests on all support points of the multi-point support with contact. Thus, at least one position of the spectacle lens can be predefined and / or at least restricted by means of the multi-point support. The multi-point support does not have to have exclusively point-shaped support points. It can also have a linear support combined with at least one support point. The support points can then be, for example,two spaced-apart points on the linear support and at least one support point are taken into account. The multi-point support preferably has only approximately point-shaped support points, since this is the most secure way for non-planar spectacle lenses to be positioned on the multi-point support. The multi-point support can also have, for example, a plurality of linear supports, which can be arranged in a star shape, for example. The spectacle lens can then be placed, for example, on the end points of the linear supports facing the center of the star, which act as quasi point-shaped support points. In this respect, the support points of the multi-point support can also act merely as a plurality of point-shaped support points, even if they have a slightly different shape, at least in part. The spectacle lens can be placed on the multi-point support with at least one rotational degree of freedom about an approximately vertical axis of rotation.The method does not require that the spectacle lens is aligned with the correct rotational orientation on the multi-point support, i.e. the functional engravings do not have to be aligned exactly to the target positions, as is the case, for example, with the control device described at the beginning. The spectacle lens can therefore be placed on the multi-point support without taking the engraving positions into account and / or precisely aligning them. This enables the spectacle lens to be placed on the multi-point support relatively freely, simply and / or quickly. It may only be necessary to place the spectacle lens on the multi-point support with a predetermined lens side, e.g. with its concave side and / or with its front side. Furthermore, depending on the design, it may be necessary to place the spectacle lens on the multi-point support at least within a predetermined support tolerance range.With the lens in this position, the engraving positions are recorded. A recording module can be used for this purpose. In particular, a nasal engraving position of a functional engraving arranged nasally from the centering point can be recorded and / or a temporal engraving position of a functional engraving arranged temporally from the centering point. The engraving positions can be recorded optically, for example using at least one camera. The engraving positions can be recorded in two-dimensional or three-dimensional form. Since the functional engravings are not always visible under normal lighting conditions, they can be made extra visible using optical recording, for example. A specially designed lighting device can be used for this purpose, which can make the functional engravings visible. Alternatively, the recording module can record the engraving positions using a light wavelength specifically suited for this purpose.The acquisition module can include an image analysis system, by means of which at least one image of the spectacle lens placed on the multi-point support can be evaluated to detect the engraving positions. For example, using a stereo camera system and / or by taking at least two images of the placed spectacle lens from at least two different recording directions, the engraving positions can also be determined in three dimensions. The acquisition module can be calibrated relative to the multi-point support and / or the support points of the multi-point support, i.e., for example, have a predetermined distance from the multi-point support.The spectacle lens position can thus be determined with knowledge of and / or consideration of the engraving positions, which can comprise at least two point positions, namely the engraving positions of the nasal and temporal functional engraving, as well as with knowledge of and / or consideration of the point positions of the support points of the multi-point support. The point positions of the support points of the multi-point support can be known in advance, e.g. as part of calibration information. In addition, a previously known lens geometry of the spectacle lens can be taken into account in the determination, e.g. surface shape information relating to a surface shape of the lens side of the spectacle lens placed on the multi-point support and / or strength information of a lens strength of the spectacle lens and / or engraving position information which contains information about the arrangement of the functional engravings on the spectacle lens.The lens position can thus be determined from the recorded engraving positions, the point positions of the support points and, if applicable, the lens geometry. The lens position can comprise relative position information with regard to one to three positional degrees of freedom and / or a rotational position with regard to one to three rotational degrees of freedom. The number of positional and / or rotational degrees of freedom can be sensibly restricted, for example depending on the design of the multi-point support, in order to simplify the determination of the lens position. Preferably, the lens position is determined so precisely that both all positional coordinates and all rotational coordinates are determined. The lens position can thus be recorded optically and mathematically, whereby the engraving positions are recorded optically and the exact lens position is calculated mathematically taking these engraving positions into account.As soon as the lens position is recorded and known, all dependent reference points on the lens are also known, for example the position of the centering point. This means that all positions at which the stamp should be positioned when correctly aligned are known. This corresponds to a target stamp position which is directly dependent on the determined lens position. Thus, after the lens position has been determined, it can be checked whether the stamp is correctly positioned, i.e. whether it correctly marks the reference points it is supposed to mark. This can be done by checking whether and / or how precisely the stamp is positioned at its target stamp position. To do this, the stamp position can first be recorded, for example using the same and / or a similar recording module with which the engraving positions are recorded.The stamp position of the stamp can be checked without the spectacle lens having to be brought into a precisely specified target position that is predetermined with regard to all rotational and translational degrees of freedom. In this way, the spectacle lens can be placed on the multi-point support with at least one relatively free rotational degree of freedom about an approximately vertical axis of rotation. By placing the spectacle lens on the multi-point support, the translational degrees of freedom can be at least restricted and / or specified. This restriction and / or specification can be fulfilled simply and / or automatically when the spectacle lens is placed. Furthermore, the spectacle lens can be placed on the multi-point support with a predetermined lens side, e.g. with its front lens side.This can correspond to a restriction and / or specification with regard to two rotational degrees of freedom, which can also be fulfilled easily and / or automatically. At least with regard to the last rotational degree of freedom, e.g. the rotational orientation of the spectacle lens around an approximately vertical axis, the positioning of the spectacle lens can be carried out relatively freely. This enables a simplified and / or shortened check of the stamp position. This check can be carried out with reduced effort. According to one embodiment, when determining the spectacle lens position, a fictitious spectacle lens position on the multi-point support with associated fictitious engraving positions is initially assumed. The fictitious spectacle lens position is varied such that the associated fictitious engraving positions approximately correspond to the recorded engraving positions.In this case, a fictitious spectacle lens can be assumed which, in terms of lens geometry, i.e., shape and functional engravings, corresponds to the actual spectacle lens and which is arranged in the fictitious spectacle lens position. The variation of the fictitious engraving positions that the spectacle lens would have if it were arranged in the fictitious spectacle lens position can be carried out under the assumption and / or condition that the corresponding fictitious spectacle lens is arranged on the multi-point support. This can be used as a boundary condition for the variation. The variation can thus, for example, essentially correspond to a virtual rotation of the fictitious spectacle lens about an approximately vertical axis of rotation, wherein the axis of rotation can, for example, run through an approximately centrally located center point of the multi-point support. The fictitious spectacle lens position can essentially be freely predetermined and / or fixed. Thus, the variation can, for example,always start with roughly the same fictitious lens position, although the fictitious lens position can be adapted to the lens geometry of the lens actually placed on the head. Alternatively, a plurality of fictitious lens positions can be specified (also adapted to the lens geometry of the lens actually placed on the head), from which one can be selected, e.g. randomly. If a variation of a first selected fictitious lens position does not lead to a satisfactory result, a different second fictitious lens position from the plurality of fictitious lens positions can be used and the variation repeated. The same can be done with a third and possibly further fictitious lens position from this plurality, e.g. until a reasonable result is achieved.In general, the variation of the fictitious lens position can be designed and / or carried out as a mathematical calculation method and / or optimization. In a further development, the fictitious lens position is optimized in an iterative process in which the distances between the associated fictitious engraving positions and the recorded engraving positions are reduced and / or minimized. The distances can be reduced and / or minimized directly and / or indirectly. If the fictitious and / or recorded engraving positions are specified, for example, in coordinates, the distances between them can be simply reduced and / or minimized, e.g. iteratively. This corresponds to a direct reduction and / or minimization of the distances. Alternatively, at least one parameter that is dependent on the respective engraving positions (e.g. geometric) can be varied, whereby an indirect reduction and / or minimization of the distances can occur.In this case, the fictitious engraving positions can be approximated to the recorded engraving positions without changing the recorded engraving positions. This adjustment can take place under at least one boundary condition, in particular under the boundary condition that the fictitious spectacle lens is placed on the multi-point support. In the iterative process, the fictitious spectacle lens position can then be varied such that the fictitious engraving positions approximate the recorded engraving positions. This eliminates the need for precise alignment of the placed spectacle lens, which simplifies verification. In a further development, the fictitious spectacle lens position is varied such that at least one fictitious geometric parameter dependent on the fictitious engraving positions approximately corresponds to an actual geometric parameter dependent on the recorded engraving positions.In this case, an indirect reduction and / or minimization of the distances between the fictitious and recorded engraving positions can thus take place, wherein the at least one fictitious geometric parameter is changed, and not the fictitious engraving positions directly. The (fictitious or actual) geometric parameter can be dependent on at least one of the (fictitious or actual) engraving positions. Preferably, the (fictitious or actual) geometric parameter is dependent on the two (fictitious or actual) engraving positions. For example, the (fictitious or actual) geometric parameter can comprise a connecting line between the two (fictitious or actual) engraving positions, e.g. a straight line through these two engraving positions. This makes it possible to vary the (e.g. one) fictitious geometric parameter instead of the coordinates of the at least two fictitious engraving positions comprising several individual parameters.This can simplify the variation and / or make it more efficient. In a further development, the fictitious lens position is varied such that a fictitious engraving center point between the fictitious engraving positions approximately corresponds to the actual engraving center point between the recorded engraving positions. The respective engraving center points can be used as geometric parameters from which the fictitious engraving center point is varied and / or optimized. Optimization can be carried out such that the distance between the fictitious engraving center point and the actual engraving center point between the recorded engraving positions is reduced and / or minimized, for example to approximately 0. This variation can essentially take place mathematically and / or automatically and / or be carried out by a software module, which can simplify checking for an operator.In a further development, the fictitious lens position is varied such that a fictitious straight line and / or line through the fictitious engraving positions approximately corresponds to an actual straight line and / or line through the recorded engraving positions. In this case, the respective straight lines and / or their straight line direction can be used as geometric parameters, from which the fictitious straight line and / or its straight line direction is varied and / or optimized. Optimization can be carried out in such a way that, for example, the angle between the fictitious straight line and the actual straight line is reduced and / or minimized, for example to approximately 0°. This variation can also be essentially mathematical and / or automatic and / or carried out by a software module, which can simplify the checking for an operator.This variation of the fictitious engraving center point and that of this fictitious straight line can be combined to increase convergence and / or to find the result more precisely. In a further development, when varying the fictitious lens position, at least one zero point search is carried out for: - the difference between the fictitious geometric parameter and the actual geometric parameter; and / or - the distance of the fictitious engraving center point from the actual engraving center point; and / or - the angle between the fictitious straight line and the actual straight line through the respective associated engraving positions. Through this zero point search, the fictitious lens is virtually and / or fictitiously rotated and / or shifted from the original fictitious lens position until the fictitious engraving positions approximately coincide with the actually recorded engraving positions.The varied fictitious spectacle lens position corresponding to the last varied fictitious engraving positions determined in this way can approximately correspond to the lens position of the real spectacle lens and be determined as the actual spectacle lens position. Such a zero point search can be carried out using a common mathematical method, e.g. using a Newton iteration and / or a (e.g. linear) system of equations. The zero point search can be largely mathematical and / or automatic. It can, for example, be carried out by an appropriately configured and / or programmed software module, which can simplify the verification of the stamp position. In one embodiment, the fictitious spectacle lens position is predetermined and independent of the actual spectacle lens position. This makes it possible to begin the variation without further specifications and / or preparations.However, the fictitious spectacle lens position may depend on the lens geometry of the actually placed spectacle lens, in particular on its shape and / or its engraving positions. The lens geometry of the spectacle lens may be known in advance and / or recorded by a software module used for the variation. This enables at least partial automation and / or simplification of the inspection. In one embodiment, the spectacle lens is placed on the multi-point support such that it is pre-positioned on the multi-point support within a placement tolerance range. The placement tolerance range may include a rotational restriction with regard to at least one degree of freedom, e.g., a rotation about an approximately vertical axis through a center point of the multi-point support.A (LQVFKUlQNXQJ^XP^HLQHQ^7ROHUDQ]ZLQNHO^Į^YRUJHEHQ^VHLQ^^6R^NDQQ^GDV^%ULOOHQJODV^VR^ can be placed on the multi-point placement such that an engraving component of the lens, e.g. the brand engraving such as the Rodenstock-R on a lens from the manufacturer Rodenstock, deviates from a target placement alignment by a maximum of the tolerance angle Į^^DOVR^XP^^Į. For example, this engraving component can be roughly aligned to the target placement alignment XQG^ XP^ PD[LPDO^ ^Į^ YRQ^ GLHVHU^ target placement alignment. Such a restriction of the placement tolerance range and / or such a pre-positioning of the lens can accelerate an optimization and / or variation of the fictitious engraving positions and / or enable their convergence. The tolerance angle can Į^]^%^^HWZD^20° to about 70°, preferably about 30° to about 60°, particularly preferably about 40° to about 50°, for example about 45°.These tolerance angle ranges allow, on the one hand, sufficient restriction to, for example, allow the variation of the fictitious engraving positions to converge reliably, and, on the other hand, sufficient placement leeway for the operator to enable simple and / or quick and / or error-free placement of the spectacle lens on the multi-point support. According to one embodiment, exactly two engraving positions are recorded and taken into account when determining the spectacle lens position. These can be the two engraving positions of the nasal and temporal functional engraving. These two engraving positions record and / or determine at least one rotational degree of freedom of the spectacle lens position. Recording and taking into account exactly two engraving positions can be sufficient for a reliable verification of the stamp position without making the verification process too complex.In one embodiment, the multi-point support is designed as a three-point support with exactly three support points. The position of the spectacle lens is determined based on the point positions of these exactly three support points. Three support points are sufficient for secure positioning of the spectacle lens on the three-point support. The use of a three-point support with exactly three support points can be sufficient for secure checking of the stamp position without making the checking process too complex, since only three support points need to be taken into account. Furthermore, the three-point support can be relatively simple in terms of components and is therefore inexpensive. According to one embodiment, the engraving positions are recorded using a camera system. In this case, a stereo camera system and / or recordings of the functional engravings from at least two different recording positions can be used to determine the engraving positions, for example.in three dimensions. This enables a very precise and therefore reliable inspection. Alternatively, even a single image from a single direction may be sufficient, e.g. if the engraving positions are only to be recorded in two dimensions, which may also be sufficient for an inspection and is mathematically less complex. The camera system can be calibrated. In particular, a distance and / or an alignment of the camera system relative to the multi-point support can be known in advance and / or measured. This calibration can include intrinsic and extrinsic calibration data, i.e., in addition to the purely geometric arrangement, it can also take into account, for example, the imaging properties of the optics. Image data acquired by the camera system can be evaluated by an algorithm in such a way that the engraving positions can be recorded. Image recognition software, for example, can be used for this purpose.According to one embodiment, the spectacle lens is placed on the multi-point support with its lens side facing away from the functional engravings and / or its convex lens side. Typically, the functional engravings are applied to the back of the lens while the lens is still blocked, which can be concave, for example. Thus, after placement with the lens side facing away from the functional engravings, which is usually the convex front of the lens, the functional engravings are arranged on the upper lens side facing away from the multi-point support. There, the camera system can directly capture the engraving positions of the functional engravings without having to take into account that the functional engravings appear to be arranged in a different position through the spectacle lens than directly captured.If the lens is placed on the multi-point support with the side of the lens on which the functional engravings are applied, the functional engravings can only be recorded through the lens. In this case, a corresponding parallax shift would have to be taken into account when determining the engraving positions, which can lead to inaccuracies. Thus, placing the lens on the multi-point support with the side of the lens facing away from the functional engravings simplifies and / or improves correct recording of the engraving positions. According to one embodiment, to check the stamp position, the actual stamp position is compared with a stamp target position dependent on the determined lens position. This comparison can be carried out by an operator and / or computer-implemented. Thus, after determining the lens position, the dependent stamp target position can first be determined and / or calculated, i.e.the position at which the stamp should correctly be positioned. A virtual stamp image aligned according to this target stamp position can be projected onto the placed spectacle lens, e.g. using an appropriately configured stamp projection device. Using the virtually displayed stamp image, the target stamp position can be compared with the actual stamp position, e.g. by an operator. In one embodiment, the actual stamp position can also be recorded, e.g. using the camera system that can also be used to record the engraving positions. The actual stamp position can be compared with the target stamp position automatically and / or with computer support. The comparison enables a simple and / or visual and / or automatic checking of the actual stamp position.One aspect relates to a device for checking the arrangement of a stamp on a spectacle lens with functional engravings, comprising a multi-point support with multiple support points for supporting the spectacle lens. A detection module is designed and / or configured to detect engraving positions of the functional engravings of the spectacle lens placed on the multi-point support. A determination module is designed and / or configured to determine a spectacle lens position of the spectacle lens thus placed based on the detected engraving positions and taking into account point positions of the support points of the multi-point support. A verification module is designed and / or configured to check a stamp position of the stamp on the spectacle lens depending on the determined spectacle lens position. The device can be used to carry out the method according to the aspect described above.For this reason, the statements regarding the method also relate to the device and vice versa. The individual modules of the device can each be at least partially implemented using software. The device has at least the multi-point support. The detection module can have a detection means, such as a camera system, by means of which the engraving positions and / or the stamp positions can be detected. Alternatively, a further detection module can be provided for detecting the stamp position. The determination module can detect the spectacle lens position, e.g. by means of optimization and / or variational calculus. The verification module can either carry out the verification automatically or at least support it, e.g. by projecting a virtual stamp image, which can be compared by an operator with the actual stamp.,P^5DKPHQ^GLHVHU^(UILQGXQJ^N|QQHQ^GLH^%HJULIIH^ÄLP^:HVHQWOLFKHQ³^XQG^RGHU^ÄHWZD³^VR^ may be used in such a way that they include a deviation of up to 5% from a numerical value following the term, a deviation of up to 5° from a direction following the term and / or from an angle following the term. Terms such as top, bottom, above, below, lateral, etc. refer - unless otherwise specified - to the reference system of the Earth in an operating position of the subject matter of the invention. The invention is described in more detail below with reference to exemplary embodiments shown in the figures. Individual features shown in the figures can be implemented in other exemplary embodiments. It shows: Figure 1 a schematic flow diagram of a method according to the invention and Figure 2 a screenshot of a checking module for checking a stamp position. Fig.1 shows an embodiment of a method 10 according to the invention in a schematic flow diagram. Some of the method steps shown in Fig. 1 are optional and do not necessarily have to be implemented in all embodiments. The method 10 can be used to check the arrangement of a stamp on a spectacle lens with functional engravings. For this purpose, the spectacle lens is positioned in a positioning step 1; preferably, it is placed on a multi-point support. The spectacle lens can be placed with a preferred side, e.g., with its front side facing down. The positioning of the spectacle lens can be achieved with at least one degree of freedom, in particular a rotational degree of freedom. A precisely defined positioning of the spectacle lens is not required. However, the degree of freedom can be restricted. For example, a rough alignment of the spectacle lens may be necessary.it may be necessary to place a component of the engravings on the multi-point support within a specified placement tolerance range. This allows a rough pre-positioning of the spectacle lens on the multi-point support, but without requiring precise alignment of the spectacle lens. This pre-positioning is therefore easy for an operator to carry out. Optionally, the functional engravings can then be made visible in a visualization step 2. This can simplify detection of the functional engravings. Depending on the detection method, in particular the light wavelengths used, the visualization step 2 can be omitted. In a first detection step 3, the engraving positions of the functional engravings of the spectacle lens positioned in this way are detected. A detection module with a camera system can be used for this purpose, for example.In a provision step 4, fictitious engraving positions of a fictitious spectacle lens position are provided. The fictitious spectacle lens position can depend on the lens geometry of the spectacle lens and / or the pre-positioning. For example, the fictitious engraving positions can belong to a fictitious spectacle lens position that the spectacle lens would assume if it were placed exactly on a target lens position, without the placement play provided by the placement tolerance range. The target lens position can, for example, be located centrally in the placement tolerance range. In a comparison step 5, a check is carried out to determine how much the fictitious engraving positions deviate from the recorded engraving positions, i.e., how far apart they are from one another. If the deviation and / or this distance is too large, i.e., greater than an acceptable tolerance, which can, for example, be specified, the fictitious engraving positions are varied and / or optimized in a variation step 6.The point positions of support points of the multi-point support and / or the actually recorded engraving positions can be included in this variation. The variation and / or optimization can thus be carried out in such a way that the spectacle lens position on the multi-point support can be determined so that the fictitious engraving positions coincide as closely as possible with the actually recorded engraving positions. The support points of the multi-point support can form the basis for the variation and / or optimization. A geometric parameter that depends on the engraving positions can be optimized. For example, a fictitious engraving center point between the fictitious engraving positions can be varied and / or shifted so that it is positioned on a real engraving center point between the recorded engraving positions.Alternatively or additionally, a fictitious straight line connecting the fictitious engraving positions can be varied and / or shifted and / or rotated so that it corresponds as closely as possible to a real straight line connecting the recorded engraving positions. During variation and / or optimization, a zero point search can be carried out, e.g. using a common mathematical method such as Newton iteration. In this way, for example, the distance between the fictitious and real engraving center point can be minimized and / or optimized towards zero. An angle and / or distance between the (fictitious and real) straight lines connecting the (fictitious and recorded) engraving positions can be minimized and / or optimized towards zero. After variation step 6, the varied fictitious engraving positions are checked again in comparison step 5 and compared with the recorded engraving positions.If the deviation between the fictitious engraving positions and the recorded engraving positions is small enough, i.e. smaller than the acceptable tolerance, the spectacle lens position is determined in a determination step 7 on the basis of the fictitious engraving positions, which then almost correspond to the recorded engraving positions. A target stamp position, which is also determined, is directly dependent on the determined spectacle lens position. The target stamp position can be determined from the determined spectacle lens position. For this purpose, the optical effect of the spectacle lens can be taken into account, in particular if the target stamp position is located on a side of the spectacle lens facing away from the recording module. In this case, a parallax shift when viewing the stamp through the spectacle lens can be taken into account.The desired stamp position can either be calculated and / or determined in the same determination step 7 as the spectacle lens position or in a separate, subsequent process step. In a second detection step 8, the stamp position can be detected, e.g. again using the detection module. In this way, the stamp position can also be optically detected, in particular using a stereo camera system. Using the spectacle lens position determined in this way, the detected stamp position can be checked in a verification step 9. In this case, a comparison can be made as to whether the stamp actually applied to the spectacle lens is at least substantially arranged on a desired stamp position that belongs to the determined spectacle lens position. The process steps shown in Fig. 1 do not necessarily have to be carried out in the order shown in Fig. 1. For example,the stamp position, which is recorded in the second recording step 8, can also be recorded at a different time, e.g. together with the functional engravings in the first recording step 3 or even before. The method 10 does not require a fixed, defined spectacle lens position on the multi-point support in which the spectacle lens must be aligned. Rather, the actual spectacle lens position is determined and / or calculated based on specific recorded points, in particular based on the support points and the recorded engraving positions. This makes it possible to calculate and / or output data to be checked, such as the stamp position, live. The target stamp position is therefore not fixed, as with the previously known checking device, but is variable at least within a storage tolerance range and is calculated depending on the determined spectacle lens position and, if applicable, a parallax shift. This simplifies the checking of the stamp position on the spectacle lens.Figure 2 shows a screenshot of a verification module for checking a stamp position. The screenshot is reproduced in black and white and has therefore been slightly edited. The verification module can be designed as a component of a device for checking the arrangement of a stamp on at least one spectacle lens with functional engravings. Fig. 2 shows, in the left and largest part, a photograph of a section of a spectacle lens 100, which is marked by a circle that is not shown in full. The photograph can have been taken using an image recording device, e.g., using a camera system. The photograph is taken from the side of the spectacle lens 100 on which functional engravings 110a and 110b are arranged. The spectacle lens 100 has at least the first functional engraving 110a and the second functional engraving 110b.These two functional engravings 110a and 110b are arranged nasally and temporally from a centering point and can be formed as part of permanent engravings of the spectacle lens 100. The centering point of the spectacle lens 100 can be arranged approximately or exactly in the middle between the two functional engravings 110a and 110b on the spectacle lens 100. The permanent engravings can include further markings, e.g., a brand engraving, an order code, a base curve, and / or a refractive index (cf. the numbers Ä40³ and Ä60³ XQG^GDV^VSLHJHOYHUNHKUWH^XQWHUH^Ä5³ in the screenshot). The two functional engravings 110a and 110b can be arranged on the back of the spectacle lens 100, which can, for example, be concave and / or can be arranged facing the eyes of a spectacle wearer in the wearing position. The engraving positions of the two functional engravings 110a and 110b are recorded, e.g. by means of image recognition software (see first recording step 3 in Fig.1). They may have been made visible beforehand (cf. visualization step 2 in Fig. 1). With the side facing away from the viewer and, for example, convex, the spectacle lens 100 is placed on three support points 120 of a multi-point support (cf. positioning step 1 in Fig. 1). On this side of the spectacle lens 100 facing away from the viewer and / or the image recording device, a stamp 130 is also applied, the stamp position of which is checked. The stamp 130 is designed in several parts and has several stamp components. The stamp 130 can, in particular, have a stamp cross 133 with which the centering cross and / or the centering point of the spectacle lens 100 is to be marked. The stamp cross 133 is located approximately centrally in a stamp eye 132 of the stamp 130, which can be designed in the form of a stylized eye.The position of the stamp cross 133 relative to the eye of the spectacle wearer does not have to be centrally arranged, but can depend on the manufacturer of the spectacle lens 100 and / or the type. The stamp 130 can also have a plurality of stamp side lines 131, which can be arranged on a line, for example, both nasally and temporally of the stamp cross 133. In the exemplary embodiment shown, the stamp 130 has two nasal and two temporal stamp side lines 131, which are all arranged on a common line. The alignment of the stamp 130 can be determined and / or checked using the stamp side lines 131. The image can be recorded using a camera system and / or a capture module and / or an image recording device.The detection module can comprise at least one camera and / or a software module that detects engraving positions of the functional engravings 110a and 110b of the spectacle lens 100 placed on the support points 120. The detected engraving positions are marked in Fig. 2 by asterisks, which are displayed centrally between the, for example, approximately semicircular functional engravings 110a and 110b. A determination module can then determine the spectacle lens position of the placed spectacle lens 100 based on the detected engraving positions and taking into account point positions of the support points 120 of the multi-point support, e.g., using method 10 shown in Fig. 1, see in particular method steps 4 to 7. The spectacle lens position can comprise both a position and an orientation of the spectacle lens 100. A tolerance range can be defined to check whether the stamp 130 is correctly arranged on the spectacle lens 100.The tolerance range represents a desired stamp position in which the stamp 130 should be arranged when correctly applied to the spectacle lens 130 (see also determination step 7 in Fig. 1). The tolerance range and / or the desired stamp position can, in particular, comprise an alignment tolerance range 140. The alignment tolerance range 140 is marked in Fig. 2 by two dashed lines arranged parallel to one another and marking the alignment tolerance range 140 between them. The alignment tolerance range 140 can at least partially encompass the centering point of the spectacle lens 100 and also the two functional engravings 110a and 110b. The alignment tolerance range 140 can connect the centers of the two functional engravings 110a and 110b. The two dashed lines marking the alignment tolerance range 140 are aligned approximately horizontally in the use position.The alignment tolerance range 140 thus marks an alignment of the spectacle lens 100 in the wear position. To verify the detected stamp position (see second detection step 8 in Fig. 8), a stamp alignment line 134 is placed through the stamp side lines 131, thereby marking an alignment of the stamp 130. The software module compares the alignment and / or position of the stamp alignment line 134 with the alignment and / or position of the alignment tolerance range 140. The result can be displayed in an angular deviation display 150. This comparison can form a component of the verification step 9 (see Fig. 1). In the exemplary embodiment, a maximum angular deviation of ±1.2° is permitted as a tolerance for the permissible deviation of the alignment of the stamp alignment line 134 from the alignment of the parallel lines marking the alignment tolerance range 140.Since the actual angular deviation in the exemplary embodiment is +1.00°, the alignment of the punch 130 lies within the alignment tolerance range 140. In an upper right-hand area of ​​the screenshot shown in Fig. 2, an area of ​​the same image around the centering point of the spectacle lens 100 is shown enlarged. Here, too, it is shown that the punch alignment line 134 is arranged approximately in the alignment tolerance range 140. A centering cross tolerance range 141 is marked around the centering point itself, e.g., as a rectangle and / or square. The centering cross tolerance range 141 can also be formed as part of the tolerance range and / or the punch target position. The centering cross tolerance range 141 can mark the area around the centering point of the spectacle lens 100, e.g., the area between the two dashed lines marking the alignment tolerance range 140.The centering cross tolerance range 141 can be approximately as wide as it is high, i.e., its vertical and horizontal extents (in the use position) can be approximately equal. The position of the stamp cross 133 is also shown in the upper right area of ​​the screenshot shown in Fig. 2. A center point of the stamp cross 133 can be marked separately, e.g., by means of a stamp cross center point marking 135, which is shown as a white dot in Fig. 2. The stamp cross center point marking 135 can be formed as a component of the stamp position (cf. second detection step 8 in Fig. 1). The software module compares the position of the stamp cross 133 and / or the stamp cross center point marking 135 with the position of the centering cross tolerance range 141. In doing so, both a horizontal deviation and a vertical deviation of the center point of the stamp cross 133 from the centering point can be checked.The result of this check can be displayed in a vertical offset display 151 and a horizontal offset display 152. In the exemplary embodiment, a position tolerance range of ±0.35 mm in the vertical direction and ±0.35 mm in the horizontal direction is defined as the permissible deviation of the center point of the punch cross 133 from the actual centering point. For the exemplary embodiment, the vertical offset display 151 shows that the vertical deviation is -0.14 mm and is therefore acceptable. As shown in the horizontal offset display 152, the horizontal deviation is -0.43 mm and is therefore unacceptable. The punch position can thus be checked using several individual punch position parameters, e.g., the punch position parameters angular deviation, horizontal offset, and vertical offset. Each of the punch position parameters can be checked using an assigned tolerance range.If one of the checked stamp position parameters lies outside the respectively assigned tolerance range, an error message can be output. If, for example, one of the checked stamp position parameters lies outside the respectively assigned tolerance range, a respective assigned display can be highlighted in color to make the error easily visible. In the exemplary embodiment, for example, the horizontal offset display 152 has a color background, e.g., red. This makes it clear at a glance that the stamp 130 fails the quality inspection. As a result, it may be necessary to remove the stamp 130 and, for example, reapply it to the spectacle lens 100. Both the checking of the alignment tolerance range 140 and the checking of the centering cross tolerance range 141 can take place in checking step 9, see Fig. 1.The alignment tolerance range 140 and / or the centering cross tolerance range 141 can be part of the desired punch position (see determination step 7), and the punch alignment line 134 and / or the punch cross center point marking can be part of the punch position (see second acquisition step 8). During the check, the software module can take into account that the punch 130 is arranged on the opposite side of the spectacle lens 100. This can be taken into account, for example, when generating the punch alignment line 134 and / or the punch cross center point marking 135.List of reference symbols 1 positioning step 2 visualization step 3 first detection step 4 provision step 5 comparison step 6 variation step 7 determination step 8 second detection step 9 verification step 10 method 100 spectacle lens 110a first functional engraving 110b second functional engraving 120 support point 130 stamp 131 stamp side marks 132 stamp eye 133 stamp cross 134 stamp alignment line 135 stamp cross center point mark 140 alignment tolerance range 141 centering cross tolerance range 150 angular deviation indicator 151 vertical offset indicator 152 horizontal offset indicator.

Claims

Applicant: Rodenstock GmbH "Method and device for checking a stamp on at least one spectacle lens" Our reference: R 3370WO ± hb / mu Patent claims 1. Method for checking an arrangement of a stamp (130) on at least one spectacle lens (100) with functional engravings (110a, 110b), wherein: - the spectacle lens (100) is placed on a multi-point support with a plurality of support points (120); - engraving positions of the functional engravings (110a, 110b) of the spectacle lens (100) placed on the multi-point support are recorded; - a spectacle lens position of the spectacle lens (100) placed in this way is determined on the basis of the recorded engraving positions and taking into account point positions of the support points (120) of the multi-point support; and - a stamp position of the stamp (130) on the spectacle lens (100) is checked as a function of the determined spectacle lens position.Method according to claim 1, wherein the determination of the spectacle lens position is initially based on a fictitious spectacle lens position on the multi-point support with associated fictitious engraving positions, and the fictitious spectacle lens position is varied such that the associated fictitious engraving positions approximately correspond to the detected engraving positions.

3. Method according to claim 3, wherein the fictitious spectacle lens position is optimized in an iterative process in which the distances between the associated fictitious engraving positions and the detected engraving positions are reduced and / or minimized.

4. Method according to claim 2 or 3, wherein the fictitious spectacle lens position is varied such that at least one fictitious geometric parameter dependent on the fictitious engraving positions approximately corresponds to an actual geometric parameter dependent on the detected engraving positions.

2.

5. The method according to one of claims 2 to 4, wherein the fictitious spectacle lens position is varied such that a fictitious engraving center point between the fictitious engraving positions approximately coincides with the actual engraving center point between the detected engraving positions.

6. The method according to one of claims 2 to 5, wherein the fictitious spectacle lens position is varied such that a fictitious straight line through the fictitious engraving positions approximately coincides with an actual straight line through the detected engraving positions. 7.Method according to one of claims 4 to 6, wherein, when varying the fictitious spectacle lens position, at least one zero point search is performed for: - the difference between the fictitious geometric parameter and the actual geometric parameter; and / or - the distance of the fictitious engraving center from the actual engraving center; and / or - the angle between the fictitious straight line and the actual straight line through the respectively associated engraving positions.

8. Method according to one of claims 2 to 7, wherein the fictitious spectacle lens position is predetermined and independent of the actual spectacle lens position.

9. Method according to one of the preceding claims, wherein the spectacle lens (100) is placed on the multi-point support such that it is prepositioned on the multi-point support within a placement tolerance range. 10.Method according to one of the preceding claims, wherein exactly two engraving positions are detected and taken into account when determining the spectacle lens position.

11. Method according to one of the preceding claims, wherein the. 3 multi-point support is designed as a three-point support with exactly three support points (120), and the spectacle lens position of the placed spectacle lens (100) is determined based on point positions of these exactly three support points (120).

12. Method according to one of the preceding claims, wherein the engraving positions are detected by means of a camera system.

13. Method according to one of the preceding claims, wherein the spectacle lens (100) is placed on the multi-point support with its lens side facing away from the functional engravings (110a, 110b) and / or its convex lens side.

14. Method according to one of the preceding claims, wherein, to check the stamp position, the actual stamp position is compared with a stamp target position dependent on the determined spectacle lens position. 15.Device for checking the arrangement of a stamp (130) on at least one spectacle lens (100) with functional engravings (110a, 110b), comprising: - a multi-point support with a plurality of support points (120) for supporting the spectacle lens (100); - a detection module for detecting engraving positions of the functional engravings (110a, 110b) of the spectacle lens (100) placed on the multi-point support; - a determination module for determining a spectacle lens position of the spectacle lens thus placed on the basis of the detected engraving positions and taking into account point positions of the support points (120) of the multi-point support; and - a verification module for checking a stamp position of the stamp (130) on the spectacle lens (100) as a function of the determined spectacle lens position.

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