METHOD FOR COMPENSATING POSITION DEFECTS IN A MOLDING PROCESS OR IN A FIXING PROCESS OF A RAW-EDGED FINISHED EYEGLASS LENS AND DEVICE FOR THIS PURPOSE

Description

[0001] The invention relates to methods for compensating position errors in a mold edging process of raw-edged finished spectacle lenses and a device therefor.

[0002] It is known from the prior art that for the edging of raw-edged, finished ophthalmic lenses, they are blocked or clamped and then ground into the frame shape using a (milling and / or grinding) tool. This process is also referred to as grinding, edging, or edge finishing.

[0003] For processing, the lenses can be clamped without a block or secured using one or more blocks and / or adhesive pads. Milling or grinding tools are used for edge processing, which grind or mill the lenses into the frame shape. Centering and shape data, which specify the coordinates and shapes for the edge-forming process, are used to control the tools.

[0004] This can lead to deviations during the grinding process due to geometric effects, such as tilting of the lenses during blocking or clamping.

[0005] However, this process is not suitable for particularly smooth glass surfaces, as the glass can slip out of its holding or blocking position. Due to the incorrect positioning of the glass, subsequent steps, such as the mold edging process, can result in faulty edge processing.

[0006] International patent application WO 01 / 704 59 A1 discloses a method in which the positioning of the raw glass can be displayed on a screen prior to the fixing process. However, if centering deviations occur during the process, they can neither be detected nor compensated for.

[0007] European patent application EP 2 199 021 A1 discloses a surface processing method for ophthalmic lenses. This method involves determining a positioning error before the surface processing process begins. The document neither addresses the problems of a mold edging process nor centering deviations that can occur after a fixation process.

[0008] From the German patent application DE 41 27 094 A1, an ophthalmic lens grinding machine is known which is processed according to specified decentration values.

[0009] The invention is based on the object of providing a method which is suitable for taking into account or compensating for position errors of a glass so that it can be shaped to the desired shape.

[0010] The problem is solved by means of a method according to the main claim and a device according to a subordinate claim.

[0011] The invention will be described in more detail below (with reference to the figures).

[0012] Furthermore, for the sake of simplicity, reference will generally only be made to one entity in the following. Unless explicitly stated, the invention may also comprise several of the entities in question. Therefore, the use of the words "a," "an," and "another" is to be understood merely as an indication that at least one entity is used in a simple embodiment.

[0013] Where procedures are described below, the individual steps of a procedure can be arranged and / or combined in any order, unless the context explicitly indicates otherwise. Furthermore, the procedures can be combined with each other unless expressly indicated otherwise. Numerical values ​​are generally not to be understood as exact values, but include a tolerance of + / - 1% to + / - 10%.

[0014] References to standards or specifications or norms are to be understood as references to standards or specifications or norms that are / were in force at the time of the application and / or, if priority is claimed, at the time of the priority application. However, this does not imply a general exclusion of applicability to subsequent or replacing standards or specifications or norms.

[0015] In the following, "adjacent" explicitly includes a direct neighborhood relationship, but is not limited to this. "Between" explicitly includes a position in which the intermediate part is in direct proximity to the surrounding parts.

[0016] The method for compensating positioning errors in a mold edging process of a raw-edged finished ophthalmic lens includes, by way of example, a step of determining centering deviation parameters. The centering deviation parameters can be indicative of a movement of the raw-edged finished ophthalmic lens (during a (mechanical) fixing process). Such movements lead to positioning errors. The (mechanical) fixing process can be carried out taking into account the determined centering deviation parameters in such a way that a movement of the raw-edged finished ophthalmic lens is compensated. At the end of the mechanical fixing process, the raw-edged finished ophthalmic lens can be fixed in such a way that further movement of the raw-edged finished ophthalmic lens is prevented during a subsequent (grinding) process. For example, control information can be changed in a further step.The control information can be changed taking into account the determined centration deviation parameters in such a way that the position errors of the raw-edged finished spectacle lens are compensated or taken into account.

[0017] This has the advantage that correct post-processing, e.g. grinding / shaping edges, of the lenses is possible quickly and cost-effectively, even with very smooth surfaces.

[0018] The device suitable for fixing and / or compensating for positional errors of a raw-edged finished spectacle lens for a grinding / edging process of the raw-edged finished spectacle lens comprises, for example: a determination means for determining (centering) deviation parameters. Furthermore, the device can comprise a fixing means for fixing the raw-edged finished spectacle lens in such a way that further movement of the raw-edged finished spectacle lens can be prevented during the subsequent (grinding) process. Furthermore, the device can comprise a control means for changing the control information based on the determined (centering) deviation parameters, wherein the (centering) deviation parameters are indicative of the occurrence of positional errors of the raw-edged finished spectacle lens during a fixing process and during a subsequent edging process.Furthermore, the device can comprise a fixing mechanism for initiating a mechanical fixing process of the raw-edged, finished spectacle lens by means of the fixing means, based on determined centering deviation parameters. The centering deviation parameters are indicative of a movement of the raw-edged, finished spectacle lens during the mechanical fixing process. The mechanical fixing process takes into account the determined centering deviation parameters in order to compensate for the movement of the raw-edged, finished spectacle lens. Furthermore, the device can comprise a control unit for transferring the control information, on the basis of which a fixing process and a subsequent mold edging process can be carried out in such a way that positioning errors of the raw-edged, finished spectacle lens are compensated or taken into account.

[0019] This has the advantage that it is possible to grind / shape the lenses correctly, quickly and cost-effectively, even on very smooth surfaces.

[0020] According to a first exemplary embodiment, the method further comprises that the movement of the raw-edged finished spectacle lens during the mechanical fixing process is caused by the mechanical fixing process, in particular towards the end of the mechanical fixing process.

[0021] This design has the advantage that less computational effort is required, since it takes advantage of the fact that the lens only begins to move when or shortly before the chuck physically touches the lens.

[0022] According to a first exemplary embodiment, the method further comprises that the occurrence of the position errors of the raw-edged finished spectacle lens is caused by the fixing process and / or the subsequent mold edging process.

[0023] This design has the advantage that less determination effort may be required and the occurring position errors can be fully compensated or taken into account, since the fact is exploited that position errors of the lens only occur when the spectacle lens comes into physical contact with the chuck and / or with the shaping tool.

[0024] According to a further exemplary embodiment, the method further comprises that the movement of the raw-edged finished spectacle lens during the mechanical fixing process comprises a displacement and / or rotation of the raw-edged finished spectacle lens.

[0025] This design has the advantage that less calculation effort is required, since it takes advantage of the fact that the glass rests on the plate and thus there are fewer degrees of freedom for the glass to move.

[0026] According to a further exemplary embodiment, the method further comprises that the occurrence of the position errors of the raw-edged finished spectacle lens comprises a displacement and / or rotation during the fixing process and / or during the subsequent mold edging process of the raw-edged finished spectacle lens.

[0027] This design has the advantage that less investigation effort may be required, as it takes advantage of the fact that the corresponding (centering) deviations are easy to determine.

[0028] According to a further exemplary embodiment, the method further comprises that the compensation of the movement of the raw-edged finished spectacle lens during the mechanical fixing process comprises a local change of a predefined fixing point on the raw-edged finished spectacle lens at the end of the mechanical fixing process.

[0029] This embodiment has the advantage that by determining a new holding point of the glass, i.e. a fixation point of the glass after the glass movement, which locally corresponds to the original fixation point on the glass, the previous centering data can continue to be used, whereby the calculation effort can be further minimized.

[0030] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters comprises reading in predetermined centering deviation parameters.

[0031] This design has the advantage that the determination of centering deviation parameters can be carried out with little effort.

[0032] According to a further exemplary embodiment, the method further comprises that the compensation of the movement of the raw-edged finished spectacle lens during the mechanical fixing process comprises a local change of a predefined fixing point on the raw-edged finished spectacle lens at the beginning of the mechanical fixing process, such that the predefined fixing point is changed such that the raw-edged finished spectacle lens is fixed at an alternative fixing point at which the movement of the raw-edged finished spectacle lens during the mechanical fixing process is minimized.

[0033] This design has the advantage that the previous centering data can still be used, which further minimizes the computation effort.

[0034] According to a further exemplary embodiment, the method further comprises that the change of the control information comprises a local change of a predefined fixation point on the raw-edged finished spectacle lens, such that the predefined fixation point is changed such that the raw-edged finished spectacle lens is fixed at an alternative fixation point at which the occurrence of position errors of the raw-edged finished spectacle lens during the fixing process and / or the subsequent mold edging process is minimized.

[0035] This design has the advantage that the original centering and / or shape data can continue to be used for the subsequent mold edging process, which minimizes the effort required for determination.

[0036] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters comprises reading in predetermined centering deviation parameters.

[0037] This design has the advantage that the fixing process can be carried out particularly quickly and with little computational effort during the fixing process.

[0038] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters comprises reading in and / or determining correspondingly modified centering data for the subsequent grinding process.

[0039] This design has the advantage that the centering data is recalculated and thus increased flexibility can be achieved, for example in the case of movements that cannot be fully reproduced, in order to continue to be able to grind accurately.

[0040] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters is carried out based on a tactile determination of the position errors of the raw-edged finished spectacle lens during the fixing process and / or during the subsequent mold edging process.

[0041] This design has the advantage that the position errors occurring during the fixing process and / or during the subsequent mold edging process can be individually and precisely compensated or taken into account.

[0042] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters is carried out based on a tactile measurement of the movement of the raw-edged finished spectacle lens during the mechanical fixing process.

[0043] This design has the advantage that the movement during the fixing process can be carried out individually and precisely.

[0044] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters is carried out based on the determination of position errors by means of position determination of at least one engraving on the raw-edged finished spectacle lens during the fixing process and / or during the subsequent mold edging process.

[0045] This design has the advantage that the position errors occurring during the fixing process and / or during the subsequent mold edging process can be individually and precisely compensated or taken into account.

[0046] According to a further exemplary embodiment, the method further comprises that the determination of centering deviation parameters is carried out based on a measurement of the movement of at least one engraving on the raw-edged finished spectacle lens during the mechanical fixing process.

[0047] This design has the advantage that the movement during the fixing process can be carried out individually and precisely.

[0048] According to a further exemplary embodiment, the method further comprises that the change of the control information comprises an additional fixation of the raw-edged finished spectacle lens such that the occurrence of position errors during the original fixation process and / or the subsequent mold edging process is minimized or even prevented.

[0049] This design has the advantage that positioning errors during the fixing process and / or during the subsequent edging process can be prevented, which allows the lenses to be edged even more precisely.

[0050] The raw-edged, finished ophthalmic lenses can be coated conventionally. With some so-called topcoats, this results in an extremely smooth surface. For example, a SuperTopCoat with a defined layer thickness can be 9 nm. This results in a reproducible and particularly smooth surface. If such a lens is then clamped, i.e. fixed, using a conventional commercially available blockless grinding machine, the smooth lens surface can cause the lens to shift from its holding position. To hold / clamp the lens, it is placed horizontally on a plate in a defined orientation in the grinding machine. Using a vacuum suction device, the lens is sucked in from the top and lifted off the plate.For mechanical fixation, a so-called chuck moves from the underside of the glass so that the glass is pressed together in a vertical direction at the holding position and ideally thus fixed. Due to the existing optical effect of the glass and / or due to the interaction of the optical effect with an existing decentration, and generally due to the curvature of the glass, a wedge, a geometric prism, is present at the holding point. The (orthogonal) force exerted on the wedge during compression can push the glass, especially glass with an (extremely) smooth surface, out of the holding position (e.g. in a horizontal plane). The force exerted on the wedge during compression can be orthogonal, essentially orthogonal, or non-orthogonal with respect to the side surfaces of the wedge. The resulting force can push the glass out of the holding position.The direction in which the lens is pressed can, for example, be in a horizontal plane, but is not limited to this. The extent of this displacement depends on the strength of the prism present at the holding point and can also depend on the type of lens, for example, the plus or minus effect in the lens, the contact pressure, the material properties of the lens (such as its mechanical hardness), the refractive index of the lens, the surface properties of the lens, and / or the properties of the lens holder of the grinding machine.

[0051] The prism present at the stopping point can be described component-wise, for example, with P_hor and P_ver, as the strength of the prism in the x-direction and in the y-direction, respectively, see Figure 1c. The deviations from the target centering data in the x-direction and y-direction and, if applicable, an axis position that occur during the grinding / mold edging process - which are collectively referred to as centering deviations - can also be described and measured separately. In order to compensate for the centering deviations that occur, the prism at the holding point can, for example, be calculated in the first step. This can be done using a calculation tool. The extension of the chuck can be taken into account, i.e. the contact surface of the chuck at the holding point of the lens, based on whose extension the prism is calculated. In the next step, the centering deviations that occur during the grinding / mold edging process, e.g. displacements and / or rotations, can be systematically determined (e.g. calculated) for various (arbitrary) prisms.This can be achieved by edge-banding raw, finished ophthalmic lenses with suitable optical powers and drawing suitable conclusions from the measurement of the centering deviations. This makes it possible to determine the positioning errors of the lens that occur during fixation and / or during the subsequent shape-banding process, such as undesired movement of the lens (at the holding point), i.e. displacements and / or twists. With suitable process parameters of the grinding machines, the centering deviations depend on P_hor and P_ver. Therefore, with sufficiently precise knowledge of this relationship, the holding position can be adjusted / changed in relation to the control information, so that the expected positioning errors (caused, for example, by movement) during fixation and / or the subsequent shape-banding process can be compensated for or taken into account accordingly.The actual positioning errors – i.e. the actual movement of the glass – can also be determined using suitable methods, so that the control information for the individual glass can be modified, thereby improving the accuracy of the compensation or the consideration of the positioning errors. The control information can, for example, be centering data and / or shape data that is transferred to a grinding machine for the shape edging process and which describes, for example, the centering and / or shape of the edge processing. Furthermore, the control information can, for example, be the holding position in which the glass is fixed. As previously described, by adapting the control information, any misalignment of the glass during the fixing process and / or during the shape edging process can be appropriately compensated for or taken into account.This method also compensates for any possible tilting of the lenses. This allows for a compensating shift and / or rotation of the holding position, corresponding to the actual movement of the lens during the fixation process.

[0052] This method also makes it possible to compensate for a tilting of a glass.

[0053] Since the prism at the holding point can be calculated for any surface geometry, this method can also be applied to any surface geometry of the lenses.

[0054] This can improve the rejection rate with regard to grinding errors, such as centering deviations outside a permissible tolerance - for example, deviation of the centering data in the x-direction and / or y-direction and / or rotation of the axis position, the latter also known as axis rotation, which can save costs and shorten delivery times.

[0055] Compensating for or taking into account positioning errors, such as lens movement, during the fixation process can also be achieved by determining an alternative holding point where the prism is small enough to minimize or even prevent lens movement. Unaltered control information can then be used for the mold edging process.

[0056] Compensating for or taking into account the positioning errors of the lens during the fixation process can also be achieved by determining an alternative holding point, which is selected so that the lenses slide or are pushed into the original holding position. Unaltered control information can then be used for the mold edging process.

[0057] Furthermore, it is possible to use a tactile measurement to observe / measure the position errors, e.g. the movement, of the lens during the fixing process and / or the subsequent edging process and, for example, to adjust the control data (or the centering data) according to this movement / position error so that the lens can continue to be ground / edged correctly or more precisely.

[0058] The determination of the position errors (e.g. the movement) can also be carried out by means of optical measurement, for example by means of a vertex refractive index meter or by means of a functional engraving applied to the lens.

[0059] Compensating for or taking into account the positioning errors of the glass during the fixation process can also be achieved by using temporary additional fixation—for example, a mechanical fixation—to minimize or even prevent the occurrence of positioning errors during the fixation process and / or during the subsequent mold edging process. Unchanged control information can then be used for the mold edging process.

[0060] In the Figure 1a-1c Schematic representations of the centering correction are shown. Figure 1a and 1bA raw-edged finished ophthalmic lens is shown as a circular outline (solid line). The desired shaped-edged lens is indicated with respect to its outline as a corresponding white section. If a position change occurs, shown as a shift from the desired centering point to the uncorrected centering point, the raw-edged finished ophthalmic lens shifts into an uncentered position, shown as a dashed, filled circular outline. This means that if the shaped-edging process were now carried out, the shaped-edged lens would become unusable if the deviation shown was as large as Figure 1b As shown, the centering point or the centering data are corrected so that the raw-edged finished lens can be correctly shaped despite the change in position.

[0061] From the Figures 2a and 2b the change in tax information can be seen.

[0062] In Figure 2aFirst, unchanged control information for a mold edging process of a raw-edged finished ophthalmic lens is shown, without taking the positioning error into account. The raw-edged finished ophthalmic lens is designated 1, and in the same reference system 2, the control information 3 (in this example, the centering point and shape for the mold edging process) is designated.

[0063] Due to positioning errors during the fixing process of the raw-edged finished spectacle lens and / or during a subsequent edging process of the raw-edged finished spectacle lens, a displacement 4 of the spectacle lens relative to the target position may occur, represented here by the raw-edged finished spectacle lens with positioning error 5. Without determining the centration deviation parameters and changing the control information, the control information continues to refer to the reference system 2 of the unshifted spectacle lens 1, whereby the positioning error is not compensated.

[0064] In this example, the original control information 3 (i.e. centering point and shape related to the original reference system 2) would be used during shape edging, resulting in an erroneous grinding result shape 3 from position error 5 (incorrect position of centering point and shape on the lens) for the displaced lens.

[0065] In Figure 2b The modified control information for a form-edging process of a raw-edged finished ophthalmic lens is shown, taking the position error into account. Here, the raw-edged finished ophthalmic lens 1 is again designated, and in the same (x,y) reference system 2, the control information 3 (in this example, centering point (x,y) and shape (x,y) for the form-edging process) is designated.

[0066] Due to positioning errors during the fixing process of the raw-edged finished spectacle lens and / or during a subsequent edging process of the raw-edged finished spectacle lens, a displacement 4 of the spectacle lens relative to the target position may occur, represented here by the raw-edged finished spectacle lens with positioning error 5.

[0067] As previously described, the control information can now be changed by determining the centration deviation parameters so that the position errors of the raw-edged finished spectacle lens can be compensated or taken into account.

[0068] In this example, the centering deviation parameters 8 are the displacement 4 of the raw-edged, finished spectacle lens in the (x,y) reference system. The change in the control information in this example comprises a translation 8 of the centering point (x → x', y → y') and, accordingly, a translation of the shape (x → x', y → y'). The changed control information 6 is shifted relative to the original (x,y) reference system 2, or is stationary in the shifted (x',y') reference system 7.

[0069] In this example, by using the changed control information for the mold edging process, the shift would be compensated, resulting in a correct grinding result of form 6 despite position error 5 (correct position of centering point and shape on the lens) for the shifted lens.

[0070] In this example, by using the changed control information for the mold edging process, the shift would be compensated, resulting in a correct grinding result of form 6 despite position error 5 (correct position of centering point and shape on the lens) for the shifted lens.

[0071] In Figure 3A are measurement results in relation to a horizontal centering deviation without the position error and Figure 3B Reference to a horizontal centering deviation is shown with consideration. The centering deviations for raw-edged, finished lenses after the edge-forming process are shown as a function of the prism at the holding point. Lenses whose centering deviations lie outside the tolerance limits are considered rejects. Figure 3A the position errors were not taken into account, as Fig. 2a described. In Figure 3B the position errors were taken into account, as Fig. 2bThe rejection rate is significantly lower when the positioning errors are taken into account (here, specifically, 0% for x-deviations across both tests).

[0072] In Figure 4A are measurement results in relation to a vertical centering deviation without the position error and Figure 3B Reference to a vertical centering deviation is shown with consideration. The centering deviations for raw-edged, finished lenses after the edge-forming process are shown as a function of the prism at the holding point. Lenses whose centering deviations lie outside the tolerance limits are considered rejects. Figure 4A the position errors were not taken into account, as Fig. 2a described. In Figure 4B the position errors were taken into account, as Fig. 2bThe rejection rate is significantly lower when the positioning errors are taken into account (here, specifically, a total of 2.7% for y-deviations across both tests).

[0073] In Figure 5 The pass / fail rates for two representative tests are shown as examples. For both tests, raw-edged, finished lenses with comparable powers were shaped. For Test A ( Figure 5 left side) the position errors were not taken into account, as Fig. 2a There is a high rejection rate (27%). For Test B / Figure 5 right side) the position errors were taken into account, as in Fig. 2b The rejection rate is significantly lower (2%).

Claims

1. A method of compensating for positioning errors in an edging process of a raw-edged finished spectacle lens, the method comprising: - determining centering deviation parameters, the centering deviation parameters being indicative of the occurrence of positioning errors of the raw-edged finished spectacle lens during a fastening process and during a subsequent edging process, and - changing control information with the aid of the determined centering deviation parameters in such a way that the positioning errors of the raw-edged finished spectacle lens are compensated for and / or taken into account, characterized in that - the determination of the centering deviation parameters comprises a calculation of a prism at the fastening point.

2. The method according to claim 1, wherein the occurrence of positioning errors of the raw-edged finished spectacle lens is caused by the fastening process and / or a subsequent edging process.

3. The method according to claim 1 or 2, wherein the occurrence of positioning errors of the raw-edged finished spectacle lens during the fastening process comprises shifting and / or twisting during the fastening process and / or during the subsequent edging process of the raw-edged finished spectacle lens.

4. The method according to any one of the preceding claims, wherein the determining of centering deviation parameters comprises reading of predetermined centering deviation parameters.

5. The method according to any one of the preceding claims, wherein the changing of the control information comprises a change in location of a predefined fastening point on the raw-edged finished spectacle lens.

6. The method according to any one of the preceding claims, wherein the change of the control information comprises a change in location of a predefined fastening point on the raw-edged finished spectacle lens such that the predefined fastening point is changed such that the raw-edged finished spectacle lens is fastened at an alternate fastening point at which the occurrence of positioning errors of the raw-edged finished spectacle lens during the fastening process and / or the subsequent edging process is minimized.

7. The method according to any one of the preceding claims, wherein the change of the control information comprises reading and / or determining correspondingly modified centering data and / or shape data for the subsequent edging process.

8. The method according to any one of the preceding claims, wherein the determination of centering deviation parameters is based on optical measurement or a tactile determination of the positioning error of the raw-edged finished spectacle lens during the fastening process and / or during the subsequent edging process.

9. The method according to any one of the preceding claims, wherein the determination of centering deviation parameters is based on the determination of positioning errors by means of positioning determination of at least one engraving on the raw-edged finished spectacle lens during the fastening process and / or during the subsequent edging process.

10. The method according to any one of the preceding claims, wherein the change of the control information encompasses an additional fastening of the raw-edged finished spectacle lens in such a way that the occurrence of positioning errors during the original fastening process and / or the subsequent edging process is minimized or even prevented.

11. The method according to any one of the preceding claims, wherein the raw-edged finished spectacle lens is mechanically fastened with a chuck during the fastening process.

12. The method according to claim 11, wherein the calculation of the prism in the fastening point is further configured in such a way that the extent of the chuck is taken into account and the prism is calculated via the contact surface of the chuck in the fastening point.

13. Apparatus for compensating positioning errors of a raw-edged finished spectacle lens, for an edging process of the raw-edged finished spectacle lens, for carrying out a method according to any one of claims 1 to 12, the apparatus comprising: - a determination means, for determining centering deviation parameters - a control means for changing the control information based on determined centering deviation parameters, wherein the centering deviation parameters are indicative of the occurrence of positioning errors of the raw-edged finished spectacle lens during a fastening process and / or during a subsequent edging process, - a control unit for transferring the control information, on the basis of which a fastening process and / or a subsequent edging process is carried out, in such a way that positioning errors of the raw-edged finished spectacle lens are compensated for or taken into account, - characterized in that the device further comprises a chuck for substantially centrally fastening the raw-edged finished spectacle lens, and characterized in that the determination means is designed in such a way that the determination of the centering deviation parameters is based on a prism in the fastening point.