DE102023109051B3 - Method and device for checking a stamp on at least one spectacle lens - Google Patents

Abstract

In a method for checking an arrangement of a stamp (130) on at least one spectacle lens (100) with functional engravings (110a, 110b), the spectacle lens (100) is placed on a multi-point support with several 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. A stamp position of the stamp (130) on the spectacle lens (100) is determined and checked depending on the determined spectacle lens position.

Description

The invention relates to methods and devices for checking an arrangement of a stamp on at least one spectacle lens with functional engravings.

To grind lenses, an optician can use reference points on the lens as a guide. Before grinding, lenses are usually round, non-round or elliptical in shape. During grinding, the lens is made to fit a selected frame and centered taking the reference points into account. During centering, the lens is aligned so that it is correctly positioned in the frame to produce an intended optical effect in relation to the eyes of the respective wearer.

A centering point can be used as one of the reference points on the 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 include the centering point, for example, 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 but remain on the lens. 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. in DIN EN ISO 13666, DIN 58208 and DIN EN ISO 21987.

The functional engravings can be applied, for example, to the back of the still blocked lens, whereby the optically relevant reference points are still known exactly in the blocked state. This is why the functional engravings can usually be positioned relatively well aligned on the lens. However, this does not always 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 is formed. This is why the stamp is usually only applied to the lens after the functional engravings.

As part of a quality control, the arrangement of the stamp, in particular its position relative to the functional engravings, can be checked. For this purpose, the stamp can be checked by stamping machines themselves. 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 in the case of lenses with a high power and/or decentration and/or tilting in the lens holder.

Such quality control can be carried out manually or manually with the help of a control device in which the lens to be tested is manually inserted by an operator. Target positions of the functional engravings can first be displayed in a camera image on a screen. The operator must then place the lens in the control device and align it there so that the functional engravings are arranged at the target positions shown on the screen. Since the functional engravings cannot usually be arranged 100% congruently at the target positions, e.g. due to manufacturing inaccuracies, this alignment process is laborious, error-prone and/or inaccurate. As soon as the lens is aligned in the control device, the position of the stamp, in particular the centering point marked by a centering cross, and/or an axial position of stamp lines can be subjected to a subjective target-actual check.

The manual alignment of the lens based on the displayed target positions of the functional engravings is time-consuming for the operator. In addition, the testing process is prone to errors because, for example, functional engravings often cannot be arranged 100% congruently in their target positions and there is some leeway in the alignment. The final assessment of the position of the stamp is also subjective and depends on the operator and is therefore difficult to qualify and/or record.

In the document EP 3 696 527 A1 Methods and devices for determining the position and/or orientation of a spectacle lens having permanent markings on a holder, in particular on a suction holder, are disclosed. In this case, an apparent position of permanent markings on the spectacle lens is detected by means of a detection device. In addition, the spectacle lens is illuminated eccentrically to an optical axis of the detection device by means of additional light sources. Reflections resulting from this are also detected. Position and/or orientation are determined on the basis of the detected reflections and the apparent position of the permanent markings.

The document EN 10 2016 009 810 A1 discloses a method for checking the centering of at least one spectacle lens, wherein the spectacle lens is arranged in a recording field of an image recording device. At least one image of the spectacle lens is recorded by means of the image recording device. Positions of Functional engravings of the spectacle lens are determined in the recorded image. Furthermore, at least one lens contour of the at least one spectacle lens is determined in the recorded image and the centering of the spectacle lens is checked taking into account the determined position of the functional engravings, the determined lens contour and a previously known, user-dependent target geometry of the centering.

Against this background, the invention is therefore based on the object of improving the verification of the arrangement of the stamp on a spectacle lens, in particular to make the verification more efficient and/or safer.

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. 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, a stamp position of the stamp on the spectacle lens is checked depending on the determined spectacle 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 as a round, elliptical, non-round or ground lens.

The spectacle lens has the functional engravings, which can include at least one functional engraving arranged nasally and one functional engraving arranged temporally from the centering point. The functional engravings can be designed as a component of permanent engravings on the spectacle lens, which cannot normally be erased from the spectacle 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 type of lens, the permanent engravings can also include, 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, for example, be arranged on the back of the lens, which can, for example, be concave and/or can be arranged facing the eyes of a spectacle wearer in the position of 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, using 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 differ slightly from one another. The centering cross can, for example, be arranged between the functional engravings, in particular approximately in the middle between the nasal and temporal functional engravings. The stamp can be attached to the lens in an erasable manner. The stamp can include further markings, e.g. (in the position of use) horizontal lines nasal and temporal from the centering cross, a prism reference point and/or a near reference point. The stamp can, for example, be arranged on the front side of the lens, which can, for example, be convex and/or can be arranged facing away from the eyes of the wearer in the position of use.

The lens can be placed on the multi-point support either with its front or its back. The lens can be placed on the multi-point support with its convex front side facing downwards. In this case, its functional engravings usually face upwards, as they are usually attached 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 number of roughly point-shaped support points on which the lens is securely supported. For example, the multi-point support can have three or four support points on which the lens rests securely.

Alternatively, the multi-point support can also be designed in a ring shape, with the multi-point support having a plurality of support points. The side of the 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 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 only 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 the spaced points on the linear support and at least one support point are taken into account. Preferably, the multi-point support has only approximately point-shaped support points, since this allows non-planar spectacle lenses to be positioned most securely on the multi-point support.

The multi-point support can also have several line supports, which can be arranged in a star shape, for example. The lens can then be placed on the end points of the line supports facing the center of the star, which act as quasi point-like 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 at least partially a slightly different shape.

The spectacle lens can be placed on the multi-point support with at least one degree of rotational freedom around an approximately vertical axis of rotation. The method does not require that the spectacle lens is aligned correctly in rotation 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 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 aligning them exactly. This enables the spectacle lens to be placed on the multi-point support relatively freely, easily 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. In addition, 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.

The engraving positions are recorded when the lens is in this position. A recording module can be used for this. 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, e.g. using at least one camera. The engraving positions can be recorded in two dimensions or three dimensions. Since the functional engravings are not always visible under normal lighting conditions, they can be made extra visible using optical recording, for example. For this purpose, a specially designed lighting device can be used, for example, with which the functional engravings can be made visible. Alternatively, the recording module can record the engraving positions using a light wavelength that is specially suitable for this purpose.

The detection module can include an image evaluation, 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, by means of 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 detection 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 known distance from the multi-point support.

The determination of the lens position can thus be carried out with knowledge of and/or consideration of the engraving positions, which can include 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 glass geometry of the spectacle lens can be taken into account in the determination, e.g. surface shape information regarding a surface shape of the glass side of the spectacle lens placed on the multi-point support and/or strength information of a glass 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 be determined from the recorded engraving positions, the point positions of the support points and, if applicable, the lens geometry. The lens position can include relative position information with respect to one to three positional degrees of freedom and/or a rotational position with respect to one to three rotational degrees of freedom. The number of positional and/or rotational degrees of freedom can be limited in a reasonable manner, 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, e.g. the position of the centering point. This means that all positions at which the stamp should be positioned when correctly arranged are known. This corresponds to a target stamp position, which is directly dependent on the determined lens position. Thus, after determining the lens position, 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, e.g. 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 lens having to be brought into a precisely specified target position, which is specified with regard to all rotational and translational degrees of freedom. This means that the lens can be placed on the multi-point support with at least one relatively free rotational degree of freedom around an approximately vertical axis of rotation.

By placing the lens on the multi-point support, the translational degrees of freedom can at least be restricted and/or specified. This restriction and/or specification can be and/or will be fulfilled easily and/or automatically when the lens is placed on the support.

Furthermore, the lens can be placed on the multi-point support with a predetermined lens side, e.g. with its front 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 alignment of the lens around an approximately vertical axis, the positioning of the 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 lens position, a fictitious lens position on the multi-point support with associated fictitious engraving positions is initially assumed. The fictitious lens position is varied so that the associated fictitious engraving positions roughly correspond to the recorded engraving positions. In this case, a fictitious lens can be assumed which corresponds to the lens geometry, e.g. the shape and the functional engravings, of the actually placed lens and which is arranged in the fictitious lens position. The variation of the fictitious engraving positions that the lens would have if it were arranged in the fictitious lens position can take place under the assumption and/or condition that the associated fictitious lens is arranged on the multi-point support. This can be used as a boundary condition of the variation. The variation can thus, for example, essentially correspond to a virtual rotation of the fictitious lens around an approximately vertical axis of rotation, whereby the axis of rotation can, for example, run through an approximately centrally arranged center point of the multi-point support. The fictitious lens position can essentially be freely predetermined and/or fixed. Thus, for example, the variation can always start with approximately the same fictitious lens position, whereby the fictitious lens position can, however, be adapted to the lens geometry of the lens actually placed on the support. Alternatively, a plurality of fictitious lens positions can be predetermined (also adapted to the lens geometry of the lens actually placed on the support), one of which 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 indirectly and/or directly. If the fictitious and/or recorded engraving positions are specified in coordinates, for example, the distances between them can be easily reduced and/or minimized, e.g. iteratively. This corresponds to an immediate reduction and/or minimization of the distances. Alternatively, at least one of the respective engraving positions dependent (e.g. geometric) parameters can be varied, whereby an indirect reduction and/or minimization of the distances can be achieved. In this case, the fictitious engraving positions can be brought closer to the recorded engraving positions without changing the recorded engraving positions. This adjustment can be made under at least one boundary condition, in particular under the boundary condition that the fictitious lens is placed on the multi-point support. In the iterative process, the fictitious lens position can then be varied so that the fictitious positions approach the recorded engraving positions. This makes an exact alignment of the placed lens unnecessary, which simplifies the inspection.

In a further development, the fictitious lens position is varied in such a way that at least one fictitious geometric parameter dependent on the fictitious engraving positions roughly 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 take place, whereby 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, which comprise several individual parameters. This can simplify the variation and/or make it more efficient.

In a further development, the fictitious lens position is varied so that a fictitious engraving center point between the fictitious engraving positions roughly corresponds to the actual engraving center point between the recorded engraving positions. The respective engraving centers can be used as geometric parameters from which the fictitious engraving center point is varied and/or optimized. Optimization can be carried out in such a way 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, e.g. becomes approximately 0. This variation can essentially be carried out mathematically and/or automatically and/or carried out by a software module, which can simplify the check for an operator.

In a further development, the fictitious lens position is varied so that a fictitious straight line and/or line through the fictitious engraving positions roughly corresponds to an actual straight line and/or line through the recorded engraving positions. 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, i.e., for example, becomes approximately 0°. This variation can also essentially be mathematical and/or automatic and/or carried out by a software module, which can simplify the check for an operator. This variation of the fictitious engraving center point and that of this fictitious straight line can be combined with one another in order to increase convergence and/or to find the result more precisely.

• - den Unterschied zwischen dem fiktiven geometrischen Parameter und dem tatsächlichen geometrischen Parameter; und/oder
• - den Abstand des fiktiven Gravurmittelpunkts von dem tatsächlichen Gravurmittelpunkt; und/oder
• - den Winkel zwischen der fiktiven Gerade und der tatsächlichen Gerade durch die jeweils zugehörigen Gravurpositionen.

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 centre from the actual engraving centre; and/or
• - the angle between the fictitious straight line and the actual straight line through the corresponding 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 roughly coincide with the engraving positions actually recorded. The varied fictitious lens position associated with the last varied fictitious engraving positions determined in this way can roughly correspond to the lens position of the real lens and can be determined as the actual 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 carried out mathematically and/or automatically to a large extent. It can be carried out, for example, by an appropriately configured and/or programmed software module, which can simplify the checking of the stamp position.

In one embodiment, the fictitious lens position is predetermined and independent of the actual lens position. This makes it possible to start the variation without further specifications and/or preparations. However, the fictitious lens position can depend on the lens geometry of the lens actually placed on the device, in particular on its shape and/or its engraving positions. The lens geometry of the lens can 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 check.

In one embodiment, the spectacle lens is placed on the multi-point support in such a way that it is pre-positioned on the multi-point support within a placement tolerance range. The placement tolerance range can 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 restriction by a tolerance angle α can be specified. The spectacle lens can thus be placed on the multi-point support in such a way that an engraved component of the spectacle lens, e.g. the brand engraving such as the Rodenstock-R on a spectacle lens from the manufacturer Rodenstock, deviates from a target placement alignment by a maximum of the tolerance angle α, i.e. by ±α. For example, this engraved component can be roughly aligned in the target placement alignment and deviate from this target placement alignment by a maximum of ±α. 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 α can be, for example, about 20° to about 70°, preferably about 30° to about 60°, particularly preferably about 40° to about 50°, i.e., for example, about 45°. These tolerance angle ranges allow, on the one hand, a sufficient restriction to allow, for example, the variation of the fictitious engraving positions to converge reliably, and, on the other hand, sufficient storage space for the operator to enable the lens to be placed on the multi-point support simply and/or quickly and/or without being prone to errors.

According to one embodiment, exactly two engraving positions are recorded and taken into account when determining the 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 lens position of the lens. The recording and consideration of exactly two engraving positions can be sufficient for a reliable check of the stamp position without making the check 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 lens placed on the lens is determined based on the point positions of these exactly three support points. Three support points are sufficient for a secure positioning of the lens on the three-point support. The use of a three-point support with exactly three support points can be sufficient for a secure check of the stamp position without making the check too complex, since only three support points have to be taken into account. Furthermore, the three-point support can be relatively simple in terms of components and therefore inexpensive.

According to one embodiment, the engraving positions are recorded using a camera system. For example, a stereo camera system and/or recordings of the functional engravings from at least two different recording positions can be used to record the engraving positions, for example in three dimensions. This enables a very precise and therefore reliable check. Alternatively, even a single recording from a single recording direction can be sufficient, e.g. if the engraving positions are only to be recorded in two dimensions, which can also be sufficient for a check and is mathematically less complex. The camera system can be calibrated. In particular, a distance and/or an orientation 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, imaging properties of the optics. Image data recorded using the camera system can be evaluated by an algorithm in such a way that the engraving positions can be recorded. Image recognition software can be used for this purpose, for example.

According to one embodiment, the spectacle lens is placed on the multi-point support with the side of the lens facing away from the functional engravings and/or its convex side. The functional engravings are usually applied to the back of the lens while the lens is still blocked, which can be concave, for example. Thus, after placing the lens with the side of the lens facing away from the functional engravings, which is usually the convex front of the lens, the functional engravings are on the upper and the side of the glass facing away from the multi-point support. There, the camera system can directly record 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 lens than they are directly recorded. This is because if the lens is placed on the multi-point support with the side of the glass on which the functional engravings are located, 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 glass facing away from the functional engravings simplifies and/or improves correct recording of the engraving positions.

According to one embodiment, in order to check the stamp position, the actual stamp position is compared with a stamp target position that depends on the determined lens position. This comparison can be carried out by an operator and/or carried out by a computer. After determining the lens position, the stamp target position that depends on it can first be determined and/or calculated, i.e. the position at which the stamp should be correctly positioned. A virtual stamp image aligned according to this stamp target position can be projected onto the placed lens, e.g. using a correspondingly configured stamp projection device. The stamp target position can be compared with the actual stamp position using the virtually displayed stamp image, e.g. by an operator. In one embodiment, the actual stamp position can also be recorded, e.g. using the camera system, which can also be used to record the engraving positions. The actual stamp position can be compared with the stamp target position automatically and/or with the aid of a computer. The comparison allows for a simple and/or visual and/or automatic verification of the actual stamp position.

One aspect relates to a device for checking an arrangement of a stamp on a spectacle lens with functional engravings with a multi-point support with several support points for placing 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 placed in this way 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. Therefore, the statements on 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 lens position, e.g. by means of optimization and/or variation calculation. 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.

In the context of this invention, the terms "substantially" and/or "about" may be used to 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.

• 1 ein schematisches Ablaufdiagram eines erfindungsgemäßen Verfahrens und
• 2 einen Screenshot eines Überprüfungsmoduls zum Überprüfen einer Stempelposition.

The invention is described in more detail below using embodiments shown in figures. Individual features shown in the figures can be implemented in other embodiments. It shows:

• 1 a schematic flow diagram of a method according to the invention and
• 2 a screenshot of a verification module for checking a stamp position.

1 shows an embodiment of a method 10 according to the invention in a schematic flow diagram. Some of the 1 The process steps shown 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. To do this, 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 the front of the lens facing downwards.

The positioning of the lens can be carried out with at least one degree of freedom, in particular a rotational degree of freedom. A precisely defined positioning of the lens is not necessary. However, the degree of freedom can be restricted. For example, a rough alignment of the lens may be necessary. For example, 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 lens on the multi-point support, but without requiring an exact alignment of the lens. This pre-positioning can therefore be easily carried out by an operator.

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, visualization step 2 can be omitted.

In a first recording step 3, the engraving positions of the functional engravings of the spectacle lens positioned in this way are recorded. For this purpose, a recording module with a camera system can be used, for example.

In a provision step 4, fictitious engraving positions of a fictitious lens position are provided. The fictitious lens position can depend on a glass geometry of the lens and/or the pre-positioning. For example, the fictitious engraving positions can belong to a fictitious lens position that the lens would take 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 arranged centrally in the placement tolerance range.

In a comparison step 5, it is checked how much the fictitious engraving positions deviate from the recorded engraving positions, i.e. how far apart they are from each other. If the deviation and/or this distance is too large, i.e. larger than an acceptable tolerance, which can be specified, for example, 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 lens position on the multi-point support can be determined in such a way 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 be used as 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 matches as closely as possible 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. For example, the distance between the fictitious and real engraving center can be minimized and/or optimized to 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 to 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 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 stamp target position, which is also determined, is directly dependent on the determined lens position. The stamp target position can be determined from the determined lens position. The optical effect of the lens can be taken into account, especially if the stamp target position is located on a side of the lens facing away from the detection module. In this case, a parallax shift can be taken into account when viewing the stamp through the lens.

The punch target position can either be calculated and/or determined in the same determination step 7 as the 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. The stamp position can also be detected optically, in particular using a stereo camera system.

Using the lens position determined in this way, the recorded stamp position can be checked in a checking step 9. In this case, a comparison can be made as to whether the stamp actually applied to the lens is at least substantially arranged on a stamp target position which belongs to the determined lens position.

In the 1 The process steps shown do not necessarily have to be carried out in the 1 shown order. For example, the stamp position which is recorded in the second recording step 8 can also be recorded at a different time, eg together with the functional engravings in the first recording step 3 or even before.

The method 10 does not require a fixed lens position on the multi-point support in which the lens must be aligned. Rather, the actual lens position is determined and/or calculated based on certain 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 control device, but is variable at least within a storage tolerance range and is calculated depending on the determined lens position and, if applicable, a parallax shift. This simplifies the checking of the stamp position on the lens.

2 shows a screenshot of a verification module for checking a stamp position. The screenshot is in black and white and has therefore been slightly edited.

The inspection module can be designed as a component of a device for checking an arrangement of a stamp on at least one spectacle lens with functional engravings.

2 shows in the left and largest part a picture of a section of a spectacle lens 100, which is marked by a circle that is not shown in full. The picture can have been made by means of an image recording device, eg by means of a camera system.

The image 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 designed as a component 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 (see the numbers “40” and “60” and the mirror-inverted lower “R” in the screenshot).

The two functional engravings 110a and 110b can be arranged on the back of the spectacle lens 100, which can be concave, for example, and/or can be arranged facing the eyes of a spectacle wearer in the position of use.

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 1 ). They may have been made visible before (see Visibility step 2 in 1 ).

With the side facing away from the viewer and e.g. convex, the lens 100 is placed on three support points 120 of a multi-point support (see positioning step 1 in 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 made up of 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 wearer does not have to be centrally located, but it can depend on the manufacturer of the lens 100 and/or the type.

The stamp 130 can also have several stamp side lines 131, which can be arranged on a line, for example, both nasally and temporally of the stamp cross 133. In the 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 recording can be made by means of a camera system and/or a recording module and/or an image recording device. The recording module can comprise at least one camera and/or a software module which records engraving positions of the functional engravings 110a and 110b of the spectacle lens 100 placed on the support points 120. The recorded engraving positions are in 2 marked by asterisks, which are displayed centrally between the approximately semicircular functional engravings 110a and 110b.

Subsequently, a determination module can determine the lens position of the applied lens 100 on the basis of the recorded engraving positions and taking into account point positions of the support points 120 of the multi-point support, e.g. based on the 1 shown method 10, see in particular method steps 4 to 7. The spectacle lens position can include both a position and an orientation of the spectacle lens 100.

To check whether the stamp 130 is correctly positioned on the spectacle lens 100, a tolerance range can be defined. The tolerance range represents a target stamp position in which the stamp 130 should be positioned if it is correctly applied to the spectacle lens 130 (see also determination step 7 in 1 ).

The tolerance range and/or the punch target position can in particular comprise an alignment tolerance range 140. The alignment tolerance range 140 is in 2 marked by two dashed lines which are arranged parallel to one another and mark 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 with one another.

The two dashed lines marking the alignment tolerance range 140 are aligned approximately horizontally in the position of use. The alignment tolerance range 140 thus marks an alignment of the spectacle lens 100 in the position of use.

To check the recorded stamp position (see second recording step 8 in 8th ), a stamp alignment line 134 is placed through the stamp side lines 131, which thereby marks an alignment of the stamp 130.

The software module compares the orientation and/or position of the punch alignment line 134 with the orientation and/or position of the alignment tolerance range 140. The result can be displayed in an angular deviation display 150. This comparison can form part of the verification step 9 (see. 1 ).

In the exemplary embodiment, an angular deviation of a maximum 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 stamp 130 is within the alignment tolerance range 140.

In an upper right area of the 2 In the screenshots shown, an area of the same image is shown enlarged around the centering point of the spectacle lens 100. Here, too, it is shown that the stamp alignment line 134 is arranged approximately in the alignment tolerance range 140.

A centering cross tolerance area 141 is marked around the centering point itself, e.g. as a rectangle and/or square. The centering cross tolerance area 141 can also be designed as part of the tolerance area and/or the punch target position. The centering cross tolerance area 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 area 140. The centering cross tolerance area 141 can be approximately as wide as it is high, i.e. its vertical and horizontal extent (in the position of use) can be approximately the same.

Also in the upper right area of the 2 The screenshots shown show the position of the stamp cross 133. 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 in 2 shown as a white dot. The stamp cross center mark 135 can be designed as a component of the stamp position (see second recording step 8 in 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 stamp cross 133 from the actual centering point.

For the embodiment, the vertical offset indicator 151 indicates that the vertical deviation is -0.14mm and is therefore acceptable. As indicated by the horizontal offset indicator 152, the horizontal deviation is -0.43mm and is therefore not acceptable.

This means that the stamp position can be checked using several individual stamp position parameters, e.g. using the stamp position parameters angular deviation, horizontal offset and vertical offset. Each of the stamp position parameters can be checked using an assigned tolerance range. If one of the checked stamp position parameters is outside the assigned tolerance range, an error message can be issued.

If, for example, one of the checked stamp position parameters is outside the assigned tolerance range, a corresponding display can be marked in color to make the error easily recognizable visually.

In the exemplary embodiment, for example, the horizontal offset display 152 is highlighted in color, e.g. red. This makes it clear at a glance that the stamp 130 does not pass the quality test.

As a result, it may be necessary to remove the stamp 130 and, for example, reattach it to the lens 100.

Both the checking of the alignment tolerance range 140 and the checking of the centering cross tolerance range 141 can be carried out in checking step 9, see. 1 . The alignment tolerance range 140 and/or the centering cross tolerance range 141 can be part of the punch target 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 detection step 8).

During the check, the software module can take into account that the stamp 130 is arranged on the opposite side of the lens 100. This can be taken into account, for example, when generating the stamp alignment line 134 and/or the stamp cross center point marking 135.

List of reference symbols

1

Positioning step

2

Visualization step

3

first recording step

4

Deployment step

5

Comparison step

6

Variation step

7

Investigation step

8th

second recording step

9

Verification step

10

Procedure

100

Lens

110a

first functional engraving

110b

second functional engraving

120

Support point

130

Rubber stamp

131

Stamp side lines

132

Stamp eye

133

Stamp cross

134

Stamp alignment line

135

Stamp cross center mark

140

Alignment tolerance range

141

Centering cross tolerance range

150

Angle deviation display

151

Vertical offset display

152

Horizontal offset display

Claims (15)

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 several 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 depending on the determined spectacle lens position. Procedure according to Claim 1 , whereby the determination of the lens position is initially based on a fictitious lens position on the multi-point support with associated fictitious engraving positions, and the fictitious lens position is varied such that the associated fictitious engraving positions approximately correspond to the recorded engraving positions. Procedure according to Claim 3 , wherein the fictitious lens position is optimized in an iterative process in which the distances between the corresponding fictitious engraving positions and the detected engraving positions are reduced and/or minimized. Procedure according to Claim 2 or 3 , wherein the fictitious 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. Method according to one of the Claims 2 until 4 , whereby 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. Procedure according to one of the Claims 2 until 5 , whereby the fictitious lens position is varied such that a fictitious straight line through the fictitious engraving positions approximately corresponds to an actual straight line through the recorded engraving positions. Procedure according to one of the Claims 4 until 6 , wherein when the fictitious lens position is varied, 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 from the actual engraving center; and/or - the angle between the fictitious straight line and the actual straight line through the respective associated engraving positions. Method according to one of the Claims 2 until 7 , where the fictitious lens position is predetermined and independent of the actual lens position. Method according to one of the preceding claims, wherein the spectacle lens (100) is placed on the multi-point support such that it is pre-positioned on the multi-point support within a placement tolerance range. 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. Method according to one of the preceding claims, wherein the 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 on the basis of point positions of these exactly three support points (120). Method according to one of the preceding claims, wherein the engraving positions are detected by means of a camera system. Method according to one of the preceding claims, wherein the spectacle lens (100) is placed on the multi-point support with its glass side facing away from the functional engravings (110a, 110b) and/or its convex glass side. Method according to one of the preceding claims, wherein, in order to check the stamp position, the actual stamp position is compared with a desired stamp position which depends on the determined spectacle lens position. Device for checking an arrangement of a stamp (130) on at least one spectacle lens (100) with functional engravings (110a, 110b) with: - a multi-point support with several support points (120) for placing 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 placed in this way 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 checking module for checking a Stamp position of the stamp (130) on the spectacle lens (100) depending on the determined spectacle lens position.

Images