Method and device for checking the centration of at least one spectacle lens and computer program product

Abstract

Method for checking the centration of at least one spectacle lens, comprising the steps: - arranging the at least one spectacle lens in a recording field of an image recording device (2); - recording at least one image of the spectacle lens by means of the image recording device (2); - Determining positions of functional engravings (11) of the spectacle lens in the recorded image, wherein, in order to determine the position of the functional engravings (11), a structure is created on a side of the spectacle lens facing away from the image recording device (2), which structure is at least partially imaged through the spectacle lens in the recorded image; - Determining at least one lens contour of the spectacle lens in the recorded image; and - Check the centration of the lens taking into account: - the determined position of the functional engravings (11), - the determined glass contour and - a previously known, user-dependent target geometry of the centering.

Description

The invention relates to a method and a device for checking the centering of at least one spectacle lens.The spectacle lenses of optical spectacles are regularly limited to specific desired specifications which can depend on the user of the spectacles. Thus, the optical lenses of the spectacles should be arranged regularly in the spectacle frame such that points of view of the eyes of the user in the position of use are arranged at predetermined positions on the respective lenses. In this context, one speaks of the spectacle lenses being correctly centered in the frame of the spectacles.A check of this centering of the spectacle lenses, i.e. a check of a production quality and / or an in-grinding quality, can be carried out either on the finished spectacles or on the shape-edged spectacle lenses.Conventionally, checking of the centering is carried out using manual measuring methods, for example by plotting the functional engravings and the dimension of distances using a pupil distance ruler at the optician. Manual checks are always prone to errors, since they are performed by human persons.Furthermore, partially automated methods for checking the centering, the grinding height and / or the pupil distance are known, in which first individual points (such as a centering point) on the spectacle lenses are premarked.The document DE 10 2008 039 416 A1 discloses a method and a device for checking the centering of spectacles. Mounted spectacle lenses are measured by means of an image recognition system, wherein permanent markings are detected. Desired centering points are determined as a function of the data containing the position of the permanent markings. Physiological data of a spectacle wearer of the spectacles are measured by means of a video centering device as actual centering points. Finally, the desired centering points are compared with the actual centering points.Optical parameters and terms such as, for example, "pupil distance", "grinding height", "centering point", "position of use", "function engraving", "visual point" etc. are defined in relevant standards such as, for example, DIN EN ISO 1366, DIN 58 208, DIN EN ISO 8624 and DIN 5340 and can be taken from these.The invention is based on the object of simplifying and / or improving the checking of the centering.This object is achieved by the subject matters of the independent claims. Embodiments of the invention are the subject matter of the dependent claims.One aspect relates to a method for checking the centering of at least one spectacle lens, having the steps:arranging the spectacle lens in a recording field of an image recording device;capturing at least one image of the spectacle lens by means of the image capturing device;determining the position of function engravings of the spectacle lens in the recorded image;determining at least one lens contour of the spectacle lens in the recorded image; andchecking the centering of the at least one spectacle lens taking into account the determined position of the functional engravings, the determined lens contour of the spectacle lens and a previously known, user-dependent desired geometry of the centering.The method can be carried out both for checking the centering of finished spectacles and for checking shape-tailored spectacle lenses. Finished spectacles here mean a spectacle frame into which spectacle lenses are inserted as optical spectacle lenses. The shape-edged spectacle lenses are intended to mean spectacle lenses which are manufactured, for example, from a spectacle lens blank and which are edged in such a way that they can be inserted into a specific spectacle frame without further processing in order thus to form finished spectacles. The method is carried out at least on a spectacle lens. In this case, it is possible in particular to carry out this simultaneously or successively on two spectacle lenses, both of which are intended for a single pair of spectacles. Since the method can be carried out regularly on the two spectacle lenses of a pair of spectacles, reference is usually made below to spectacle lenses, i.e. in the plural, even if the method can in principle also already be carried out on a single, for example shape-edged spectacle lens.In the method, the finished spectacles or the shape-edged spectacle lenses are first arranged in the recording field of the image recording device. The image recording device can be a camera, in particular a digital camera such as a CCD camera. The recording field of the image recording device can be a substantially three-dimensional spatial region which can be recorded by the image recording device. The recording field regularly comprises a spatial region in front of an objective and / or a lens of the image recording device, which is intersected by an optical axis of the image recording device.The finished spectacles and / or the shape-edged spectacle lenses can be arranged at a previously known distance and orientation from the image recording device, in particular from an optical recording axis of the image recording device. This distance and this alignment can be part of a calibration, which is taken into account in checking the centering.The image is recorded with the image recording device; in particular, a digital image of the finished spectacles or the shape-edged spectacle lenses can be recorded and / or created. The image contains at least parts of the finished spectacles or the shape-edged spectacle lenses. In particular, the image can substantially completely contain the two shape-edged spectacle lenses or the finished spectacles. The image recording device can be used to record either a single image or a plurality of images. The recorded image preferably contains an image section in which a spatial region and / or object arranged behind the spectacle lenses (i.e. on the side of the spectacle lenses facing away from the image recording device) is imaged through one or both of the spectacle lenses. The image can be recorded at least partially from a perspective toward or in a zero-view direction through the eyeglasses and / or the shape-edged eyeglasses.After the image has been recorded, the position of the functional engravings of the finished spectacles or of the shape-edged spectacle lenses in the recorded image is determined. Optical lenses usually have at least two functional engravings, which can be used to correctly center, edge and / or arrange the spectacle lenses in a spectacle frame. The exact position of the functional engravings on the spectacle lenses can vary from manufacturer to manufacturer. Spectacle lenses regularly have two functional engravings, one of which is arranged nasally and temporally from an optical center and / or a centering point of the respective spectacle lens. In decentered lenses, the optical center and / or the centering point of the spectacle lens can also be offset upwards or downwards with respect to the functional engravings.Since function engravings are usually not recognizable with the naked eye, the function engravings can first be made visible before their position in the recorded image is determined. For this purpose, for example, a specifically arranged illumination unit can be provided, which is arranged and / or designed such that the functional engravings can be identified, recognized and / or determined in the recorded image. In this case, the functional engravings can be made visible in particular by recording a screen through the spectacle lenses, on which screen one or more different patterns is / are displayed, such as, for example, strip projections. A further possibility for visualizing the functional engravings can be effected by means of a retro-reflection unit, as is described, for example, in the publication DE 103 33 426 A1. A further possible implementation includes automatic recognition of the engravings, as described for example in the publication DE 10 2014 005 281 A1.The positions of the functional engravings made visible in this way in the recorded image can be determined graphically, for example, in particular under software control. In this case, first of all pixel positions can be determined in the recorded image, which can be converted into two-dimensional and / or three-dimensional coordinates, in particular into world coordinates in the reference system of the earth.Furthermore, the lens contours of the spectacle lenses are determined in the recorded image, i.e. for example at which positions the spectacle lens edges are arranged in the recorded image. In this case, in particular the pixel positions of the spectacle lens edges can be determined. It may be sufficient to determine the glass contours at least partially and / or in sections and / or pointwise. The determination of the lens contours can be performed on the finished spectacles differently from on shape-edged spectacle lenses without a frame. Thus, for the determination of the lens contours of finished spectacles, the determination of a single spectacle reference point may be sufficient, while for the determination of the lens contours of shape-edged spectacle lenses more positions in the recorded image are determined. Determining the lens contours can contain information about where (e.g. at which pixels) the spectacle lens edges are arranged around the recorded image.The checking of the centering of the finished spectacles or of the shape-edged spectacle lenses takes place taking into account both the determined positions of the functional engravings and also taking into account the determined position of the at least one reference point and / or the determined lens shape. Furthermore, additional data can be taken into account in the checking, in particular previously known user-dependent data. These previously known, user-dependent data can be referred to as the desired geometry of the eyeglasses and / or of the eyeglasses. Thus, the desired geometry can comprise a desired centering of the finished spectacles and / or the shape-restricted spectacle lenses, in particular a desired pupil distance and / or a desired grinding height. Further, the prior art data may include, for example, glass thickness. When checking the centering, it can be checked whether points of view of the eyes of a user for whom the spectacles have been or are to be manufactured are arranged at predetermined positions on the respective spectacle lenses of the spectacles in the use position. In this case, determined actual positions of the view points can be compared with theoretical target positions of the view points.When checking the centering, it can be determined whether the actual positions of the view points deviate from the desired positions of the view points by a maximum of a predetermined value. This predetermined and / or permissible deviation from the positions of the points of view can be dependent on the type of spectacle lens. Thus, a permissible deviation, for example in progressive lenses, can be less than a permissible deviation in spectacle lenses with a single vision. The check can thus include a check as to whether or not permissible deviations of the centering are observed.The method provides a possibility of checking the centering of the finished spectacles and / or the shape-finished spectacle lenses as automatically as possible. In the method, the source of human error can be excluded or at least reduced. The checking is carried out at least partially automatically, in particular substantially fully automatically. When determining positions in the recorded image, i.e. in particular when determining the position of the functional engravings, when determining the lens contours of the spectacle lenses, a manual confirmation of individual points in the recorded images by an optician or another operator can additionally be provided. In other embodiments, this manual check may be omitted.The method simplifies and improves the checking of the centering of the finished spectacles or of the shape-edged spectacle lenses. In particular, no points need to be marked on the spectacle lenses when checking the centering. A manual measurement of the centering can be dispensed with.According to one embodiment, the at least one spectacle lens is provided either in finished spectacles or as a shape-edged spectacle lens. In this case, the lens contour of the spectacle lens in the recorded image is eitherdetermining the position of at least one spectacle reference point of the spectacles in the recorded image, ordetermining a lens shape of the shape-edged spectacle lens in the recorded image.In this case, the centering of the eyeglasses or of the shape-edged eyeglass lenses is checked taking into account the ascertained position of the eyeglass reference point or of the ascertained lens shape.The method step of ascertaining the lens contours is therefore here ascertaining the position of at least one spectacle reference point of the finished spectacles in the recorded image and / or a lens shape of the shape-edged spectacle lenses in the recorded image.In this exemplary embodiment, it is thus differentiated whether the centering is checked on finished spectacles or whether the centering of shape-edged spectacle lenses is checked. Depending on this, the individual method steps can be carried out differently, in particular the determination of the glass contours.In the event that the centering on a finished pair of spectacles is checked, the position of at least one spectacle reference point of the finished pair of spectacles can be determined in the same image and / or a further recorded image. As a spectacle reference point, for example, a center point of the nose bridge of the spectacles can be determined. The spectacle reference point serves to be able to compare and relate the positions of the function engravings to the orientation and position of the spectacle frame. In particular, it can be determined on the basis of the spectacle reference point how the spectacle lenses are arranged in the spectacle frame. If this at least one spectacle reference point is determined in the recorded image, sufficient data for checking the centering of the finished spectacles are determined together with the positions of the functional engravings. In this case, starting from the spectacle reference point, previously known frame data (such as e.g. a frame contour) of the spectacle frame can be taken into account in order to determine and / or determine the glass contours in the recorded image.If the centering on shape-edged spectacle lenses which have not yet been inserted into a frame is checked, then instead of the spectacle reference point the lens shape of the shape-edged spectacle lenses can be determined at least partially. This can be done individually for each shape-edged spectacle lens, or simultaneously for the two shape-edged spectacle lenses of a single spectacle lens on the basis of a single image in which both shape-edged spectacle lenses are imaged. In this case, in particular, a contour of the shape-edged spectacle lenses, that is to say a course of the edges of the shape-edged spectacle lenses, can be determined at least partially in the recorded image, in particular graphically and / or with software assistance. From the lens shape and / or the lens contour, it can be estimated at which positions relative to the function engravings in the finished spectacles the frame edge and / or the spectacle lens edge will be arranged. When ascertaining the lens shape, it may be sufficient to ascertain at least three points spaced apart from one another, preferably at least four points spaced apart from one another, on each of the shape-edged spectacle lenses in the recorded image. In this case, in particular a temporal, a nasal, an upper and / or a lower point on the spectacle lens edge can be determined in order to determine the lens shape. By ascertaining the lens shape of the shape-edged spectacle lenses, the lens contour of the spectacle lenses is thus ascertained.By this distinction between checking the centering of finished spectacles and checking the centering of shape-edged spectacle lenses, the individual method steps are optimized for the respective application.According to one embodiment, a parallax shift is taken into account when checking the centering of the spectacle lenses if the function engravings are arranged on the side of the spectacles or of the shape-edged spectacle lenses which is remote from the image recording device when recording the image. The parallax shift is taken into account when checking the centering and can be included in the calculation of the visual point(s). The parallax shift can occur when the function engravings are arranged on the side of the spectacle lenses which is remote from the image recording device. In this case, the functional engravings are recorded in the recorded image through the spectacle lenses.When calculating the parallax shift, further data can be used, in particular at least one thickness, at least one refractive index, at least one optical intensity, at least one lens angle and / or at least one pre-tilt of the spectacle lenses can be taken into account. Thus, the actual (or real) position of the function engravings can deviate by up to one or even several millimeters from the position at which they are determined directly (i.e. without taking into account the parallax shift) in the recorded image. Thus, by considering the parallax shift, the checking of the centering is improved. If the image is recorded from the side of the spectacle lenses on which the functional engravings are arranged, it is possible to dispense with taking account of the parallax shift. Since the function engravings can be arranged on the side of the spectacle lenses facing the user and on the side facing away from the user depending on the manufacturer, checking for the presence of a parallax error improves the versatility of the method.According to one embodiment, when determining the position of the functional engravings, a structure is arranged on a side of the spectacle lenses facing away from the image recording device, which structure is imaged at least partially in the recorded image through the spectacle lenses. The structure can be generated, for example, by a screen and / or projected onto the spectacle lenses. The structure can be designed in particular as a stripe pattern and / or can have at least one pattern with a plurality of contrast transitions between differently illuminated regions. As an alternative to a screen, the structure can also be formed as a ready-produced static structure, for example printed on a film or a print surface, which has been produced in advance. During the recording of the image, the structure is arranged on the side of the spectacle lenses which is recorded during the recording of the image through the spectacle lenses. In the recorded image, it is possible, for example, to determine graphically and / or under software control, where, for example, a disturbance of the structure indicates that a function engraving or an edge of the spectacle lens is arranged at this position. The use of the structure thus simplifies and / or enables the determination of the positions of the functional engravings, the knowledge of which is further processed for checking the centering. In other words, the structure makes the functional engravings visible and / or determinable in the recorded image.According to one exemplary embodiment, at least one lens frame angle of the spectacle lenses is determined and the determined lens frame angle is taken into account when checking the centering of the spectacle lenses. The frame lens angle is defined in the standards listed at the beginning and describes an inclination of the spectacle lenses in the frame of the spectacle about an axis of rotation which is oriented substantially vertically in the position of use. Taking into account the mounting disk angle improves the checking of the centering. It is therefore advantageous to include the mounting disk angle in the checking of the centering. The frame lens angle must normally only be taken into account when checking finished spectacles, since shape-edged spectacle lenses can be arranged substantially without this inclination relative to the optical recording axis of the image recording device. When checking the centering of shape-edged glasses, instead of the mounting disk angle, an angle of inclination of the shape-edged glasses relative to the optical recording axis of the image recording device can be taken into account and / or determined in advance, which substantially corresponds to the mounting disk angle. Instead of checking the frame lens angle, it is thus also possible, more generally, to determine and take into account the (e.g. horizontal and / or vertical) orientation and / or inclination of the spectacle lenses relative to the optical recording axis of the image recording device.In a development of this embodiment, the frame lens angle (or, more generally, the alignment and / or inclination of the spectacle lenses relative to the optical recording axis) is determined by evaluating a reflection of at least one laser line on the spectacle lenses. In the method, the frame slice angle (or the orientation and / or inclination) is thus determined exactly, at which the spectacle lenses are arranged in the recording field of the image recording device. For this purpose, for example, the reflection of a laser line can be used, which is generated by a laser scanner via the finished spectacles or the shape-edged spectacle lenses. The position of the laser line can vary. In particular, when using a scanner, the laser line can be projected over parts of the surface of the spectacle lenses. The laser line can be arranged in particular transversely over both spectacle lenses of the spectacles, that is to say in a substantially horizontal and / or nasal-temporal direction in the position of use. Such an alignment of the laser line simplifies the determination of the lens angle, which likewise describes an inclination of the lenses in a substantially nasal-temporal direction. The reflection of the laser line can either be registered and / or evaluated by means of a separate measuring device, or detected and / or determined by means of the image recording device. In particular, the reflection of the laser line in the image recorded by the image recording device can be determined, registered and / or evaluated.Here, as the laser line, laser light of a wavelength of about 400 nm to about 500 nm can be used. For determining the frame lens angle (or, more generally, the alignment and / or inclination of the spectacle lenses relative to the optical recording axis), a blue laser light is thus used. Blue light has the advantage over red light that a larger component thereof is reflected on spectacle lenses which are often configured to be weakly reflective in the red wavelength range. The restriction to a wavelength above about 400 nm further excludes the use of UV light. Although the reflection for UV light on spectacle lenses would usually be even better than for blue light, additional measures would be required to protect an operator when UV light is used. Therefore, blue laser light is particularly well suited for determining the mounting disk angle.Alternatively to the determination of the lens frame angle by means of a laser line which is projected onto the spectacle lenses, the lens frame angle can be determined from production data of a spectacle frame of the spectacles and / or by means of an external measuring device. Thus, the frame angle can be known beforehand, for example, since it is firmly predefined for the eyeglasses. The mounting disk angle can either be taken over directly from the production data or can be determined, for example, with the aid of another external measuring device. In this case, the mount disk angle or angles determined are registered, for example manually entered or automatically transmitted to a checking device, and taken into account in checking the centering.According to one embodiment, in the case that the centering on at least one shape-edged spectacle lens is checked, the shape-edged spectacle lens is arranged at a frame lens angle of approximately 0° (or more generally: practically without inclination of the shape-edged spectacle lenses relative to the optical recording axis) in the recording field of the image recording device, wherein the frame lens angle is ignored during checking the centering (or more generally: the orientation and / or inclination of the shape-edged spectacle lenses relative to the optical recording axis). During the examination of the shape-edged spectacle lenses, these can be arranged in the recording field of the image recording device such that the image recording device records the image substantially perpendicularly through the shape-edged spectacle lenses. In other words, the optical recording axis of the image recording device is substantially perpendicular to the surface of the shape-edged lenses, so that the optical recording axis of the image recording device is arranged at a target lens angle of 0° substantially parallel to the viewing direction (at least in a projection onto a horizontal plane from the use position). In this case, when checking the centering on the basis of the recorded image, a mount disk angle of approximately 0° can be assumed. Therefore, the mounting disk angle does not have to be taken into account when checking the centering. The same or similar can apply to a pre-tilt of the shape-edged spectacle lenses. By not taking into account the mount disk angle, the check can be simplified.According to one embodiment, a pre-tilt of the spectacle lenses is determined and the determined pre-tilt is taken into account when checking the centering of the spectacle lenses. The pre-inclination of spectacles is also defined in the standards mentioned at the beginning and describes an inclination of the spectacle lenses about an axis of rotation which, in the position of use, is aligned substantially horizontally running through both spectacle lenses. The pretilt can be determined, similar to the frame angle, by means of an evaluation of a reflection of at least one laser line on the spectacle lenses. In this case, the laser line can be projected in particular in a substantially vertical direction over the spectacle lenses. The term vertical refers to the position that the finished spectacles or the shape-edged spectacle lenses would assume in the position of use(s). In this case, the laser line can be designed in particular as a blue laser line for the reasons described above. Alternatively or additionally, previously known values for the pre-tilt can be used and / or determined from manufacturing data of a frame of the spectacles, or the pre-tilt can be determined by means of an external measuring device. Taking account of the pre-tilt further improves the checking of the centering.One aspect relates to a device for checking the centering of spectacle lenses, comprising:a glass receptacle for receiving the spectacle lenses;an image recording device for recording an image of the spectacle lenses arranged in the lens holder;a engraving determination means for determining positions of functional engravings of the spectacle lenses in the recorded image;a geometry determination means for determining lens contours of the spectacle lenses in the recorded image; anda checking means for checking the centering of the spectacle lenses taking into account the determined position of the functional engravings, the determined lens contours and a previously known user-dependent desired geometry of the centering.The apparatus can be used in particular for carrying out the method according to the aspect described above. Therefore, all the statements made in connection with the preceding aspect also relate to the device and vice versa. In the device, the image recording device can be designed, for example, as a digital camera, in particular as a CCD camera. The lens holder can be designed for recording and / or arranging the finished spectacles or the shape-edged spectacle lenses in the recording field of the image recording device. Image processing can be provided as the engraving determination means, in particular software-controlled graphical evaluation of the recorded image can take place. The geometry determination means can likewise be realized by a graphic evaluation, in particular by a software-controlled and / or software-supported graphic evaluation. The checking means can also be controlled by means of software.In one embodiment of the device, the checking means takes into account a parallax shift when checking the centering of the spectacle lenses if the function engravings are arranged on the side of the spectacle lenses which is remote from the image recording device when recording the image. In this case, the checking means can first check and / or determine on which side of the spectacle lenses the function engravings are arranged. Subsequently, depending on the result, the checking means can either take into account the parallax shift or not.According to one embodiment, the device has an orientation determination means for determining an orientation of the spectacle lenses relative to an optical recording axis of the image recording device, wherein the checking means is designed to take into account the determined orientation when checking the centering of the spectacle lenses. In this case, the orientation determination means can be designed in particular as a mounting disk angle determination means and / or a pre-tilt determination means. As described in connection with the preceding aspect, the orientation determination means may include, for example, a projector for a laser line that projects at least one laser line onto and / or over the finished eyeglasses and / or the shape-edged eyeglasses. The orientation determination means can in particular contain a laser scanner, preferably a laser scanner which emits blue laser light.According to one embodiment, the image recording device has a telecentric objective. A telecentric objective is particularly suitable for producing a recording of the finished spectacles or the shape-edged spectacle lenses in which the positions of individual points are determined, since the recorded images have no distortions. In particular, a telecentric objective can particularly well record a structure through the spectacle lenses, which structure can be graphically evaluated in order to determine individual positions on the spectacle lenses.According to one embodiment, the device has a structure generating means for generating a structure on the side of the spectacle lenses facing away from the image recording device, wherein the structure can be imaged in the recorded image through the spectacle lenses. A screen and / or a (e.g. illuminated) structured surface can be used as structure generating means, for example. If a screen is used as the structure generating means, the structure can be controlled in a targeted manner, in particular a brightness of the structure can be set and / or the dimensions of individual elements of the structure can be adjustable.According to one embodiment, the glass receptacle is substantially transparent and / or the glass receptacle receives the finished spectacles or the shape-edged spectacle lenses at a lateral region with respect to an optical recording axis of the image recording device. This configuration of the lens holder makes it possible to record the image such that, for example, a structure through the lenses is contained in the recorded image. In particular, for this purpose, the glass receptacle can be transparent, for example made of a glass and / or plastic. Alternatively and additionally, the glass receptacle can hold the eyeglasses or the eyeglasses only on an edge region, that is to say on a lateral and / or temporal region, with the result that the receptacle can be made through the eyeglasses despite the use of the glass receptacle.One aspect relates to a computer program product which contains program parts which, when executed on a processor, determine the position of the function engravings, determine the lens contours of the spectacle lenses (which therefore determine, for example, the position of the spectacle reference point of the spectacles and / or the lens shape of the spectacle lenses) in a method according to the first aspect and check the centering of spectacles or of the spectacle lenses. Furthermore, program parts of the computer program product can carry out further steps of the method, such as, for example, the determination of a lens frame angle, the determination of a pre-tilt and / or a corresponding consideration of the orientation / tilt of the spectacle lenses when checking the centering.The invention is described in more detail below with reference to exemplary embodiments shown in figures. Individual features shown in the figures may be realized and / or implemented in other embodiments. Like reference numerals may identify like or similar features of the embodiments. The following are shown: FIG. 1 shows a schematically illustrated device for checking the centering of finished spectacles and / or shape-edged spectacle lenses; FIG. 2 shows schematically illustrated spectacles which are examined by a holder-lens-angle-determining means; FIG. 3 is a schematic illustration of how frame pane angles of spectacles are determined from a surface profile; and FIG. 4 shows a schematic flow diagram of a method for checking the centering of finished spectacles or shaped spectacle lenses.FIG. 1 shows a schematic illustration of a device 1 for checking the centering of spectacle lenses, that is to say the centering of finished spectacles 10 and / or the centering of shape-edged spectacle lenses. The device 1 has an image recording device 2, which can be designed, for example, as a CCD camera. The image recording device 2 has an objective 3, which can be designed in particular as a telecentric objective. The orientation of the objective 3 determines the orientation of the optical recording axis of the image recording device 2.The image recording device 2 is oriented such that the optical recording axis of the image recording device 2 points from the objective 3 of the image recording device 2 toward the eyeglasses 10 which are arranged in the recording field of the image recording device 2.In the figures, a Cartesian coordinate system is shown, in which the coordinates are denoted by x, y and z. Here, the x and z directions may be substantially horizontally oriented directions, while the y direction may be oriented in a vertical direction, i.e., facing from top to bottom.The terms horizontal and vertical refer to directions relative to the eyeglasses 10 when worn in the use position. In the use position, the x direction points from the lens center of a spectacle lens in a substantially nasal or temporal direction, while the z direction substantially coincides with the zero viewing direction. The y-direction points substantially vertically downwards from an upper spectacle lens edge to a lower spectacle lens edge, namely in the use position.In FIG. 1, the optical recording axis of the image recording device 2 is arranged such that it is arranged substantially parallel to the z direction, namely facing counter to the direction of view.The produced spectacles 10 are arranged in the recording field of the image recording device 2 such that the image recording device 2 can record an image which contains both the spectacles 10 and a structure generating means 6 which is arranged on the side of the spectacle lenses of the spectacles 10 facing away from the image recording device 2. In other words, an image can be recorded by the image recording device 2 by the structure generating means 6 through the spectacle lenses of the spectacles 10.The structure generating means 6 can be designed in particular as a screen on which a structure is displayed. The structure can be formed, for example, as a stripe pattern and / or comprise stripes. When an image of the structure generated by the structure generating means 6 is captured through the lenses of the eyeglasses 10, irregularities of the structure can be recognized. These irregularities can be assigned, for example, to functional engravings of the spectacle lenses and / or edges of the spectacle lenses.The spectacles 10 can be arranged on and / or in a glass receptacle 7. The glass receptacle 7 can be designed as a holder, in particular as a transparent holder. The transparent formation of the lens image allows the image pickup device 2 to take an image through the lenses of the eyeglasses 10 from the pattern displayed by the pattern generation means 6. The glass receptacle 7 can alternatively or additionally be designed as a lateral clamping device which holds the eyeglasses 10 only on edge sides adjacent to the eyeglass frame, in order thus not to obstruct or only slightly obstruct the reception of the structure through the eyeglass lenses.The apparatus 1 further comprises an orientation detection means 5. The orientation determination means 5 can be designed as a laser scanner which is designed and provided to project a laser line 4 onto the spectacles 10. The mode of operation of the orientation determination means 5 is discussed in more detail in the following figures.The device 1 is designed and provided for capturing an image of the eyeglasses 10. Instead of the eyeglasses 10, the two eyeglasses of the eyeglasses 10 could also be used in a shape-edged state to capture the image. The device 1 records at least one image of the eyeglasses 10, in which it detects the functional engravings of the eyeglasses 10 and determines their position.FIG. 2 shows a schematic illustration of the finished spectacles 10. As indicated in the figure by the infinity signs, the eyeglasses 10 have at least two functional engravings 11 on each of the two shape-edged eyeglasses.The exact position of the function engravings 11 depends on the manufacturer and / or the exact glass model. Typically, each spectacle lens has at least two of the functional engravings 11. In this case, the function engravings 11 are not arranged directly in the center or optical center of the respective spectacle lens, but rather are arranged in particular on the left and right, that is to say temporally and nasally offset with respect to the point of view of a user of the spectacles. In the case of decentral spectacles, the function engravings 11 can also be arranged offset upwards or downwards.This is the case, among other things, in order not to impair the optical properties of the respective spectacle lens at the point of view. With the naked eye, the functional engravings 11 of a spectacle lens are usually not visible or can only be seen with great difficulty. In order to be able to detect and / or determine the position of the function engravings 11 in the recorded image, the function engravings are first made visible. Various possibilities are available for this purpose.The image recording device 2 is oriented such that it has the functional engravings 11 of the spectacle lenses arranged next to one another and / or of the finished spectacles 10 in the image field and / or in its recording region. Since the lenses can have different curvatures and / or thicknesses, and furthermore since the mount of the lenses 10 can also have different curvatures, the image is recorded through the telecentric objective 3 in order always to obtain a sharp image without perspective distortions. Here, calibration may be used to obtain distances and positions of the function engravings 11 in world coordinates in a plane, for example. This calibration can contain knowledge about the distance of the eyeglasses 10 or the lenses from the image recording device 2, as well as a fixedly predefined orientation of the eyeglasses 10 or the lenses relative to the optical recording axis of the image recording device 2.In other embodiments, the eyeglasses 10 can also be accommodated in the direction of view. If not the centering of finished spectacles 10 but only of the shape-edged spectacle lenses without a frame is checked, the spectacle lenses can be arranged at a previously known distance from the image recording device 2 such that the image recording 2 takes place in the direction of view through the spectacle lenses. In this case, for example, a three-point support can be provided as a glass receptacle 7 for the convex side of the spectacle lenses, which receptacle receives these spectacle lenses.As part of the calibration, the distance of the structure generating means 6 from the image recording device 2 can also be known in advance. In general, for visualizing the function engravings 11, an illumination unit can be used which is optimized such that the visibility of the function engravings 11 can be established and / or is given in the image recorded by the image recording device 2. As such a lighting unit, the pattern generation means 6 may be used. For the precise detection of the position of the function engravings 11 in world coordinates, a plurality of images can be recorded here, for example at different illumination settings and / or pattern settings of the structure generating means 6. The function engravings 11 can lead to the positions of the function engravings 11 being able to identify a disturbance of the recorded pattern and / or of the recorded structure in the recorded images.A further possibility for visualizing the functional engravings 11 is offered by using a retroreflective unit which is used in addition to an illumination unit. In this way, the function engravings 11 can be recognized automatically.In the recorded image, at least one spectacle reference point can additionally be graphically determined, in particular the center of the nose bridge of the finished spectacles 10. In the case of shape-finished spectacle lenses, the approximate lens shape can instead be detected and / or determined in order to be able to check the centering.In other words, for example, the lens holder 7 can be designed such that it has at least one special marking which facilitates the detection of the spectacle reference point in the recorded image. The marking can in particular mark the spectacle reference point in the recorded image.The positions of the function engravings 11 and / or of the spectacle reference point can be determined by means of software and / or by means of graphic evaluation by a processing device which evaluates and / or examines the at least one recorded image. The processing device can have a processor and / or be designed as a computer on which corresponding software runs. The processing device may also perform the process of final checking of the centering data. In this case, the processing device can provide an output which indicates to an operator whether the centering of the spectacles 10 is sufficient or not.In the checking of the centering, in particular in the evaluation in the processing device, knowledge can be taken about at least one of the frame lens angles at which the spectacle lenses are arranged on the spectacles 10.FIG. 3 shows a schematic illustration of the two mounting disk angles α and β. Here, α denotes the right side lens angle and the reference sign β denotes the left side lens angle of the spectacles 10.Depending on the mount disk angle α, β, distortions can occur in the recorded image, which can be taken into account in the precise position determination of the function engravings 11. The determination of the mounting disk angle α, β can be carried out in different ways. Thus, the values of the mounting disk angles α, β can be read out from a database in which the mounting disk angles are stored. The database can store the values of target mount disk angles which result from the production data of the mounts, i.e. for example from 3D design data. When using the target mounting disk angles from such a database, a relatively simple and rapid determination of the mounting disk angles α, β can be carried out.However, since these theoretical target lens angles do not always correspond to reality, and in particular deviations can occur both during the production of the spectacle lenses and during the insertion of the spectacle lenses into the lens, which changes the real lens angles, the use of these theoretical target lens angles is sometimes inaccurate.For this reason, the real mount disk angles α and β are preferably determined and used in checking the centering. For this purpose, the mount disk angles α and β can be determined, for example, with an external measuring device, for example a tracer or a mechanical mount disk angle meter.Preferably, in addition to the gravity visualization, the device 1 has its own measuring device for the frame lens angles α and β of the inserted eyeglasses 10. For this purpose, a surface measurement of the eyeglasses 10 can be carried out by analysis of a reflection of one or more laser lines. For this purpose, the orientation determination means 5 can be provided, which can be designed in particular as a mount disk angle determination means and which can have a laser scanner, for example. The orientation determination means 5 projects at least the one laser line 4 over the surface of the spectacles 10, which is shown in more detail in FIG. 2, in which the laser line 4 is projected over the spectacles 10 substantially horizontally, i.e. approximately parallel to the x-direction. In this case, the laser line 4 is preferably projected beyond the surface of the spectacles 10 offset with respect to the function engravings 11. As a result, the detection of the function engravings 11 is not disturbed by the laser line 4 in the recording.For this purpose, the laser line 4 is preferably generated with a blue light which is reflected particularly well on the surface of spectacle lenses without providing a risk for an operator, such as UV light, for example.From the exact course of the laser line 4 in the recorded image, a surface course 20 can be determined, which, as embodied in FIG. 3, runs substantially along the surface of the spectacle lenses. The surface profile 20 results from the surface scan, which can be carried out and / or evaluated by means of the orientation determination means 5. The reflection of the at least one laser line can be detected by an additional recording device, or else by the image recording device 2. the exact course of the laser line 4 can be arranged aligned with the image recording device 2, so that, for example, conclusions can be drawn about the course of the laser line 4 on the basis of previously known and / or determined positions in the recorded image. Furthermore, the positions of the frame and / or the spectacle lens edges in space and / or in world coordinates can be determined and determined on the basis of the course of the laser line 4. In other words, the course of the laser line 4 is aligned with the eyeglasses 10 and / or the eyeglasses, and this alignment is known to the processing device. In particular, in the case of a previously known glass geometry, the exact position of the spectacle lenses in space can be determined and / or determined.In this case, a pre-inclination of the spectacle frame can furthermore be determined and taken into account in the checking of the centering. For this purpose, at least one second laser line can be projected onto the eyeglasses 10 or the lenses, which can be oriented, for example, substantially perpendicularly to the laser line 4. For this purpose, the orientation determination means 5 can likewise be configured. In particular, at least one laser line aligned substantially parallel to the y-axis can be projected onto the spectacle lenses on each of the two spectacle lenses, from which the pretilt can be calculated. This laser line for determining the pretilt can also be blue and can be projected onto the spectacles 10 or the spectacle lenses offset from all the functional engravings 11.How the surface profile 20 of the spectacles 10 shown in FIG. 3 can be used for calculating the frame lens angles α and β is known to the person skilled in the art and can be taken from the standards mentioned at the beginning, for example. For this purpose, as an intermediate step, for example, a mounting plane F can be determined, which is likewise shown in FIG. 3. The mounting disk angles α and β can be determined as intersection angles with the mounting plane F, in particular from geometric and radiation-optical calculations.If instead of the eyeglasses 10 only shape-edged lenses are examined, then, as already mentioned above, a lens holder 7 can be used which arranges the eyeglass lenses approximately at a holder lens angle of approximately 0° in the recording field of the image recording device 2. Therefore, in this case, the checking of the centering can be performed without considering the rim disk angle and / or the pre-tilt. Alternatively, the exact alignment of the shape-edged spectacle lenses in the recording field of the image recording device 2 can also be determined as described above with the aid of at least one laser line 4 which is projected onto the spectacle lenses by the alignment determination means 5.From the frame lens angles α and β and / or the orientation / inclination of the spectacle lenses, for example, with the aid of the associated theory data, such as, for example, a lens thickness, a front surface, a rear surface, etc., a parallax shift which may occur can be calculated by beam calculation when the functional engravings 11 are observed through the spectacle lenses. By taking into account the parallax shift, deviation of the real positions of the function engravings 11 from the positions of the function engravings 11 determined in the image can be determined accurately. The exact position of the different functional engravings 11 can thus be used to check the centering. By checking the centering, the manufacturing quality and / or the grinding-in quality of the finished spectacles or the shape-edged spectacle lenses are checked.A printed film can also be used as structure-producing means 6, which can be illuminated specifically, for example.The surface profile 20, as is illustrated in FIG. 3, can be determined completely, for example, with the aid of a laser scan as described. Alternatively, only parts of the surface profile 20 can be determined which can be extrapolated up to the frame edges. From the end points of the surface course 20, the mount disk angles α and β can be calculated.FIG. 4 shows a schematic flow diagram of an embodiment of a method for checking the centering of finished spectacles or of shape-edged spectacle lenses. In this case, first of all, in a step ST 1, the object to be examined (i.e. the finished spectacles or the shape-edged spectacle lenses) is arranged in the lens receptacle 7, cf. also FIG. 1.Subsequently or already before this, theoretical target positions of the function engravings 11, i.e. positions at which the function engravings 11 should be arranged, are calculated in a step ST 2 if the spectacles 10 or the spectacle lenses are correctly centred. In this case, in particular a desired distance from a nasal and / or temporal glass edge can be calculated and a desired distance from a lower and / or upper glass edge can be calculated. The desired distances can be calculated for all four function engravings 11 (i.e. two per spectacle lens). In this case, the desired distances can be calculated either with respect to an actual spectacle lens edge or with respect to the edge of a rectangle which is placed around the respective spectacle lens on which the respective function engraving is arranged. Such a rectangle surrounding the spectacle lens is regularly used in the box dimension and / or box system in the edging and / or grinding of spectacle lenses and is known to the person skilled in the art.A nasal edge of the surrounding rectangle can be determined by subtracting from the mount center half the distance between the lenses, which is also abbreviated as AzG. This means the bridge width of the spectacle frame.Furthermore, in a step ST 3, a theoretical nominal rotation of the lenses can be calculated, i.e. a rotation under which the lenses are arranged in the recorded image. The desired torsion may include, for example, a theoretical desired frame disk angle and / or a theoretical desired pretilt. The rotation can mean both a rotation of the lenses of the produced spectacles and a rotation of shape-edged lenses which are not yet inserted into a spectacle frame. The theoretical desired rotation may include an orientation and / or inclination with respect to the optical recording axis of the image recording device 2.As already stated above, in a step ST 4, an image of the eyeglasses 10 or of the eyeglasses is captured, for example, by the image capturing device 2 shown in FIG. 1. Both the eyeglasses 10 or the eyeglasses are contained in the image, and a structure, for example, which is provided by the structure generating means 6. Furthermore, the image can contain light from an illumination source which serves for visualizing and / or marking the function engravings 11. If the structure generating means 6 is formed as a screen, both the structure and the light can be provided from the screen.In the recorded image, in a step ST 5, a lens contour of the spectacle lenses is determined, on the basis of which, for example, a surrounding rectangle around the two spectacle lenses can be created for further calculation. It is also possible to detect only at least one spectacle reference point, on the basis of which the orientation, inclination etc. of the spectacle frame can be determined in the recorded image.In the recorded image, the position of the function engravings 11 is also determined in a step ST 6. Here, at least the positions of two functional engravings 11 can be determined per spectacle lens.In the recorded image, the positions of the function engravings 11 can first be present in pixel coordinates. The same applies to the lens contours of the spectacle lenses and / or the positions of the spectacle reference points. The pixel coordinates can be converted in a step ST 7 into SI units with knowledge of a calibration, for example in millimeters and / or in world coordinates.The distances of the respective function engravings can then be calculated with the aid of the determined positions. In this case, both the distances from a nasal and / or temporal edge of the surrounding rectangle can be determined in a step ST 8 and the distances from a lower and / or upper edge of the surrounding rectangle can be determined in a step ST 9. In other words, actual distances are calculated in steps ST 8 and ST 9, in contrast to the desired distances calculated above in step ST 2, which should have the positions of the function engravings if a correct centering is present.When checking the centering, an actual rotation of the spectacle lenses can furthermore be taken into account in a step ST 10, in particular the actual frame angle and / or the actual pre-tilts of the spectacle lenses. Alternatively or additionally, an actual vertical inclination and / or an actual horizontal inclination of the glasses can be taken into account. Furthermore, a parallax shift can be taken into account in the calculation of the actual distances from the desired distances, which is always obtained when the function engravings 11 are arranged on the side of the spectacle lenses facing away from the image recording device 2.Finally, in a step ST 11, the position deviations (ACTUAL-TARGET) of the individual functional engravings 11 can be calculated, i.e. in particular a deviation of the actual position from the previously theoretically determined target position of the functional engravings.To check the centering, in a step ST 12, in particular an actual pupil distance (abbreviated as actual PD) and / or an actual grinding-in height (abbreviated as actual ESH) can be compared with the respectively associated desired pupil distance (abbreviated as desired PD) and / or a theoretically determined desired grinding-in height (abbreviated as desired ESH). It is thus possible to calculate how much the actual PD deviates from the desired PD and / or how much the actual ESH deviates from the desired ESH, for example by means of the equations: andIn the calculation, a distinction is made between the position of the nasal impression and the position of the temporal impression. The nasal engraving is here that functional engraving of the respective spectacle lens which is arranged closer to the nose of the user in the use position, while the temporal engraving is that functional engraving of the respective spectacle lens which is spaced further from the nose of the user in the use position.If the determined deviation is less than a permissible and / or permissible deviation, the result of the check can be that a sufficiently good centering is present. If at least one of the two actual values deviates from the theoretically determined target values to a greater extent than a permissible tolerance allows, the checking of the centering can be negative. Depending on the result of the check, an output can be carried out which indicates to an operator which result the check has resulted.Optionally, a rotation of the respective spectacle lens within the frame can additionally be checked. In this case, the rotation can be calculated and / or measured from the actual position of the functional engravings. The checking of the rotation of the spectacle lens or lenses can be incorporated into the result of the checking of the centering.The exemplary embodiment shown in FIG. 4 is to be understood as an example. Instead of the pupil distance and the grinding height, a deviation from an absolute desired position could also be checked, for example in the two-dimensional box dimension or in three-dimensional world coordinates.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.List of reference characters1 Device 2 Image recording device 3 Objective 4 Laser line 5 Orientation determination means 6 Structure generation means 7 Glass recording 10 Spectacles 11 Function engraving 20 Surface profile F Mounting plane α Right mounting disk angle β Left mounting disk angle

Claims

Method for checking the centering of at least one spectacle lens, having the steps: - arranging the at least one spectacle lens in a recording field of an image recording device (2); - recording at least one image of the spectacle lens by means of the image recording device (2); - determining positions of function engravings (11) of the spectacle lens in the recorded image, wherein, in order to determine the position of the function engravings (11) on a side of the spectacle lens facing away from the image recording device (2), a structure is generated which is imaged at least partially in the recorded image through the spectacle lens; - determining at least one glass contour of the spectacle lens in the recorded image; and - checking the centering of the spectacle lens taking into account: - the determined position of the function engravings (11), - the determined glass contour and - a previously known, user-dependent desired geometry of the centering.Method according to Claim 1, wherein - the spectacle lens is provided either in finished spectacles (10) or as at least one shape-edged spectacle lens, - the lens contour of the spectacle lens in the recorded image is either determined - by ascertaining the position of at least one spectacle reference point of the finished spectacles (10) in the recorded image or - by ascertaining a lens shape of the shape-edged spectacle lens in the recorded image; and - the centering of the finished spectacles (10) or of the shape-edged spectacle lens is checked taking into account the ascertained position of the spectacle reference point or of the ascertained lens shape.Method according to Claim 1 or 2, wherein a parallax shift is taken into account when checking the centering of the spectacle lens if the function engravings (11) are arranged on the side of the spectacle lens which is remote from the image recording device (2) when recording the image.Method according to one of the preceding claims, wherein at least one frame disk angle (α, β) of the spectacle lens is determined and the determined frame disk angle (α, β) is taken into account when checking the centering of the spectacle lens.Method according to Claim 4, wherein the holder lens angle (α, β) is determined by evaluating a reflection of at least one laser line (4) on the spectacle lens.Method according to claim 5, wherein laser light of a wavelength of about 400 nm to about 500 nm is used as the laser line (4).Method according to Claim 45, wherein the lens frame angle (α, β) is determined from production data of a spectacle frame for the spectacle lens and / or by means of an external measuring device.Method according to one of the preceding claims, wherein, in the case that the centering on at least one shape-edged spectacle lens is checked, the shape-edged spectacle lens is arranged at a frame lens angle (α, β) of approximately 0° in the recording field of the image recording device (2), wherein the frame lens angle (α, β) is ignored when checking the centering.Method according to one of the preceding claims, wherein a pre-tilt of the spectacle lens is determined and the determined pre-tilt is taken into account when checking the centering of the spectacle lens.Device (1) for checking the centering of at least one spectacle lens, having: - a lens holder (7) for holding the at least one spectacle lens; - an image recording device (2) for recording an image of the spectacle lens arranged in the lens holder (7); - a engraving determination means for determining positions of functional engravings (11) of the spectacle lens in the recorded image; - a structure generation means (6) for generating a structure on the side of the spectacle lens remote from the image recording device (2), wherein the structure in the recorded image can be imaged through the spectacle lens; - a geometry determination means for determining at least one lens contour of the at least one spectacle lens in the recorded image; a checking means for checking the centering of the at least one spectacle lens taking into account: the determined position of the functional engravings (11), the determined lens contour and a previously known, user-dependent desired geometry of the centering.Device (1) according to claim 10, wherein the checking means takes into account a parallax shift when checking the centering of the spectacle lens if the function engravings are arranged on the side of the spectacle lens which is remote from the image recording device when recording the image.Device (1) according to Claim 10 or 11, having an orientation determination means for determining an orientation of the spectacle lens relative to an optical recording axis of the image recording device (2), wherein the checking means is designed to take into account the determined orientation when checking the centering of the spectacle lens.The device (1) according to any one of claims 10 to 12, wherein the image recording device (2) comprises a telecentric objective (3).Device (1) according to one of Claims 10 to 14, wherein the glass receptacle (7) is substantially transparent and / or the glass receptacle (7) records the at least one spectacle lens at a lateral region with respect to an optical recording axis of the image recording device (2).Computer program product which contains program parts which, when executed on a processor, determine the positions of the function engravings (11), determine the lens contour of the at least one spectacle lens and check the centering of the at least one spectacle lens in a method according to one of Claims 1 to 9.

Images