COMPUTER IMPLEMENTED METHOD FOR IDENTIFYING PRINTING PARAMETERS OF INKJET PRINTING DEVICE, DATA PROCESSING SYSTEM, INKJET PRINTING METHOD, AND INKJET PRINTING DEVICE - Patent application

Abstract

To inkjet-print a printing pattern on a curved surface of a spectacle lens substrate with a high printing pattern characteristic.SOLUTION: In a computer-implemented method for determining printing parameter values of an inkjet printing device for printing a pattern on a surface (3) of a spectacle lens substrate (4), the inkjet printing device includes a printhead (5) with a plurality of printing nozzles (6, 6a, 6b, 6c). The method comprises: grouping the plurality of printing nozzles into at least two printing nozzle groups, and individually determining a printing parameter value for at least one adjustable printing parameter of each printing nozzle group. Therefore, a printing pattern can be inkjet-printed on a curved surface of a spectacle lens substrate with a high printing pattern characteristic.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a computer-implemented method for identifying printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, an inkjet printing device including a print head with a plurality of printing nozzles, a data processing system, a computer program, a non-transitory computer-readable storage medium, an inkjet printing method, an inkjet printing device, and an eyeglass lens substrate having a pattern printed on its surface. [Background technology]

[0002] Inkjet technology is used for various purposes in the field of spectacle lenses, such as for permanent or temporary lens marking as disclosed in WO 2010 / 084272 A1 and WO 2014 / 053716 A1.

[0003] DE 10 2007 037 730 A1 discloses a method for manufacturing a spectacle lens, in which a first and a second marking are provided on, in or under the surface of a first and a second optically active area, respectively. The second marking has a predefined three-dimensional positional relationship with respect to the first marking. Both markings are applied by inkjet printing.

[0004] Furthermore, inkjet printing can be used to deposit maskings on partial areas of the surface of coated or uncoated spectacle lenses, as disclosed in US 2019 / 0310492 A1, the inkjet printing process disclosed therein being considered the closest prior art to the present invention.

[0005] Prior art printers used in the spectacle lens industry use "flatbed" type printheads optimized for the deposition of target material on flat surfaces. These printers therefore give good results, especially for spectacle lenses that are flat and have a small curvature. During the jetting process, the nozzles are filled with ink and ejected (=eject droplets) from them by utilizing shock waves resulting from a piezoelectric actuation. The nozzles can be finely controlled by applying specific voltage profiles to them. Typical solid ink printers operate at 300-1000 dpi and jetting frequencies of 10-50 kHz. Among other adjustable parameters are firing frequency, waveform, norm, and jetting temperature.

[0006] However, the inventors of the present invention noticed print quality problems when using inkjet technology on eyeglass lenses with higher curvatures. The inventors found that different areas of the lens have different quality of printing performed there. For eyeglass lenses with high curvature, the print quality degrades significantly towards the edge of the eyeglass lens. This was believed to be a direct result of the mismatch between the bar-like shaped prior art industrial print heads and the non-flat, e.g. spherical or freeform, optically powered surfaces of eyeglass lenses. For example, the applicant's current portfolio of this patent application utilizes blanks with actual front curves between 40mm and 1000mm.

[0007] WO 03 / 023684 A1 deals with the fabrication of three-dimensional decorated objects from flat substrates. If the substrate is decorated prior to the fabrication process, the decoration may become misaligned and distorted during the fabrication process by flowing and stretching the substrate to fit the shape of the mould or die. If the substrate is decorated after the fabrication process, the distortion of the decoration can be eliminated. However, the three-dimensional shape prior to decoration makes the decoration process complicated and costly. Adaptive pre-decoration methods utilize purposefully distorted decorations, which are applied to flat substrates. As the shape and surface of the substrate change during fabrication, the distorted decoration is intended to transform into its desired appearance. Similar problems have been noted in the fields of in-mold decoration and insert-mold decoration, as well as in the field of image projection onto curved surfaces.

[0008] To address these problems, WO 03 / 023684 A1 proposes a system and method for computationally deforming the appearance of an image to match the topography of the substrate to which it is to be applied. The proposed method involves measuring the topography of the substrate and transforming an undeformed graphical image into a deformed graphical image according to the measured values ​​of the substrate topography. However, this method requires a complex determination of the substrate topography. Furthermore, WO 03 / 023684 A1 mentions inkjet printing as a suitable method for applying the deformed graphical image to the substrate, but does not consider the impact of the application method on image distortion.

[0009] WO 01 / 73492 A2 discloses a method for applying lenticular technology to a curved surface such that a viewer experiences little image distortion. The method includes preparing an interlaced image for application to a curved surface that includes two or more frames such that the interlaced image appears substantially distortion-free when viewed through a lenticular lens from a predetermined viewing distance. The interlaced image can be printed by inkjet printing. However, the effect of the inkjet printing method on image distortion is not mentioned.

[0010] WO 2018 / 197003 A1 discloses a system and method for coating a lens using multiple inkjet print heads arranged in a linear fashion. Based on the image to be printed on the lens, multiple image layers are generated based on the shape of the lens, the target product, and the number of print heads. At least two of the multiple inkjet print heads are used to print the image on the lens, whereby each of the at least two print heads prints at least one image layer of the multiple image layers. To print the image, multiple printing passes are required that are associated with the movement of either the print heads and / or the lens. Therefore, a suitable hardware configuration for the movement is required, and the overall process can be time consuming.

[0011] EP 2 555 043 A1 discloses a method for inkjet printing markings on spectacle lenses. Different printing parameter values ​​are selected depending in particular on the surface properties of the lens, for example the properties of the coating to be applied thereto. Thus, although an individualization is made for each lens, each lens is coated with the same parameter values ​​for each printing nozzle. Therefore, the printing result may not be satisfactory due to the curvature of the lens.

[0012] WO 2020 / 079624 A1 discloses a method for positioning a glass support during movement and a method comprising the positioning method for printing an image on the glass support. Summary of the Invention [Problem to be solved by the invention]

[0013] With regard to the above-mentioned prior art, it is an object of the present invention to provide a method that allows inkjet printing of a print pattern on a surface of an eyeglass lens substrate, for example a curved surface, with higher print pattern quality.

[0014] Another object of the present invention is to provide a data processing system, an inkjet printing method, and an inkjet printing apparatus that achieve better printing results on the surface of an eyeglass lens substrate, especially on a curved surface. [Means for solving the problem]

[0015] The first object is achieved by a computer-implemented method for determining printing parameter values ​​as claimed in patent claims 1 and 20. The other objects are achieved by a data processing system as claimed in claims 11 and 32, by an inkjet printing method as claimed in claims 15 and 35 and by an inkjet printing apparatus as claimed in claims 17 and 37. The dependent claims contain further developments of the invention.

[0016] Throughout this specification the following definitions apply:

[0017] The term "adjustable ink properties" refers primarily to properties of the ink that can be adjusted by the user, such as the temperature of the ink, the solids content of the ink, and the like.

[0018] The term "analyzed data" refers to data obtained by analyzing the printed pattern, for example, by optical microscopy or white-color interferometry.

[0019] The term "arc length" refers to the distance between two points on the surface of an eyeglass lens substrate, measured along the surface (see FIG. 4).

[0020] A surface is called "spherical" when it is part of a surface of revolution whose curvature varies continuously over all or part of its area (ISO 13666:2019(E), clause 3.4.3).

[0021] The term "computer" refers to a functional unit capable of performing substantial calculations, including many numerical and logical operations, without human intervention. A computer may be a stand-alone unit or it may include multiple interconnected units (ISO / IEC 2382:2015).

[0022] The term "computer-implemented" is intended to cover patent claims involving a computer, a computer network, or other programmable apparatus in which at least one feature is implemented by a computer program, e.g., a computer-implemented method is a method actually executed on a computer.

[0023] The term "computer program" refers to a sequence of computer-executable instructions that specify a method. It is a syntactic unit consisting of declarations and statements or commands that conform to the rules of a particular programming language and are necessary to accomplish a particular function, task or problem (ISO / IEC 2382:2015).

[0024] The term "cost function" refers to a more-dimensional mathematical function that defines the cost of a particular set of printing parameters corresponding to a particular cloud of points on the surface of the eyeglass lens substrate. A particular path in the cost function that defines a low cost or even a minimum cost is used to estimate the parameter map. The cost can be defined as one or more quality parameters, e.g. the higher the quality parameter, the lower the cost. Depending on the specific application, the weights of different quality parameters in the cost function can be varied, i.e. one or more particular quality parameters can be emphasized by assigning them a higher weight than other quality parameters.

[0025] The term "curved surface" refers to a surface that is not flat and exhibits concave or convex portions or both.

[0026] The term "data" refers to any interpretable representation of information in a formalized way suitable for communication, interpretation, or processing (ISO / IEC 2382:2015).

[0027] The term "data processing" refers to the systematic performance of operations on data, such as numerical or logical operations on data, merging or sorting data, assembling or compiling programs, or operations on text, such as editing, sorting, merging, storing, retrieving, displaying or printing (ISO / IEC 2382:2015).

[0028] The term "data processing system" refers to one or more computers, peripheral devices, and software that perform data processing (ISO / IEC2382:2015).

[0029] The term "displacement vector" refers to a geometric object, possibly referencing a particular reference point, that has a magnitude or length and a direction, respectively, that describes the position of the eyeglass lens substrate and the print head relative to each other.

[0030] The term "distance" refers to the length of space between two points. Unless otherwise specified, this refers to the shortest straight line distance between the two points.

[0031] The term "jet temperature" refers to a printing parameter that describes the temperature at the print nozzle tip.

[0032] The term "environmental conditions" refers to conditions, such as temperature, humidity, etc., within the environment of the eyeglass lens substrate and the inkjet printing device used to print the pattern on the surface of the eyeglass lens substrate.

[0033] By "freeform surface" is to be understood a complex surface that can be represented in particular by an areally defined function, in particular by an areally defined function that is twice continuously differentiable. Examples of suitable areally defined functions are (in particular piecewise) polynomial functions (in particular polynomial splines, such as bicubic splines, splines of degree 4 or higher, or polynomial non-uniformly advantageous B-splines (NURBS)). Simple surfaces, such as spherical, aspheric, cylindrical, toroidal surfaces, which are described as circular along at least one principal meridian, are to be distinguished from this. In particular, a freeform surface does not have to exhibit axial or point symmetry and can have different values ​​of the mean surface refractive index for different areas of the surface. A spectacle lens presenting a freeform surface can be considered as a variable power lens according to ISO 13666:2019(E), clause 3.7.7, i.e. a spectacle lens with a smoothly varying focal power over part or all of its area, designed to provide multiple focal powers.

[0034] The term "geometric features" refers to the geometric properties of the spectacle lens substrate, e.g. its dimensions, its surface curvature, etc. and of the print head, e.g. its dimensions, orientation, spacing of individual nozzles, nozzle arrangement, etc. The surface curvature can be described, for example, by a surface sag function.

[0035] The term "geometric relationship" refers to the alignment of the print head and the eyeglass lens substrate with respect to each other, which can be described, for example, by a displacement vector, a velocity vector, an incidence angle α, a distance, or an arc length.

[0036] The term "gray level" refers to the number of drop sizes that a nozzle can produce, including "null drops" when no drops are fired.

[0037] The term "incidence angle" refers to the angle α between the normal vector n of a particular point on the surface of the eyeglass lens substrate and the ejection vector j along which the ejected ink is transported from the nozzle to the lens surface (see FIG. 4).

[0038] The term "ink" refers to any composition of matter, regardless of color, that can be deposited by droplets in an inkjet printing process (the "jetted material"). The ink may need to be heated to a certain temperature to enable or facilitate the formation and deposition of the droplets.

[0039] The term "inkjet printing" refers to drop-on-demand inkjet printing, a non-contact method of producing patterns on a surface by discrete deposition of ink droplets. Inkjet printing is performed by an inkjet printing device that includes a printhead with multiple printing nozzles.

[0040] The term "input data" refers to data that is entered into a data processing system, or any part thereof, for storage or processing. It can also refer to data that has been received or is to be received by any component of a computer (ISO / IEC 2382:2015).

[0041] The term "instruction" refers to a specification of an operation and the identity of any associated operands (ISO / IEC 2382:2015).

[0042] The term "firing duration" refers to a printing parameter that describes the amount of time during which ink is ejected from a particular print nozzle.

[0043] The term "firing frequency" refers to a printing parameter that describes the amount of firing events of a particular print nozzle per unit of time, e.g., per second or per minute. Typical firing frequencies are in the kilohertz range, e.g., 10-50 kHz.

[0044] The term "lookup table" refers to a data array that correlates adjustable printing parameters with different parameters, such as parameters that describe the geometric relationship between the spectacle lens substrate surface and the print head. Lookup tables can be stored and used for parameter mapping as needed.

[0045] The term "material properties" refers to the properties of the ink and / or the properties of the spectacle lens substrate and its surface, respectively. Examples of material properties of the ink are static and dynamic viscosity, static and dynamic surface tension, charge, etc. Examples of material properties of the spectacle lens substrate and its surface are surface hydrophobicity, surface charge, surface treatment, surface functionality, etc.

[0046] The term "non-adjustable ink properties" refers to properties of ink that cannot be adjusted by the user, such as the chemical composition of the ink.

[0047] The term "non-transitory computer-readable storage medium" refers to a storage medium for permanent data storage, i.e. data is stored even in the absence of electricity. Examples include flash memory, read-only memory, ferromagnetic random access memory, most kinds of magnetic computer storage devices, such as hard disk drives, floppy disks, and magnetic tapes, and optical disks.

[0048] The term "norm value" refers to a printing parameter that describes the multiplication variable factor by which the voltage applied to a particular printing nozzle is adjusted. The norm value adjustment is used to calibrate the firing signal of the printhead. The norm value can be thought of as a variable factor that quantifies the change in firing voltage for each nozzle.

[0049] The term "optimization" refers to a process aimed at reaching an optimal value of one or more properties. For example, optimizing a parameter map means that the parameter map is improved with respect to a particular property or target value.

[0050] The term "pattern" refers to one or more macroscopic elements, such as numbers, graphic characters of any kind, graphic representations such as dots, symbols, and the like.

[0051] The term "parameter" refers to a variable value that describes a particular characteristic of an object or process, e.g., temperature, distance, dispense frequency, etc. A parameter refers to a particular "parameter value," which may be constant or may vary, e.g., 25° C., 10 mm, 20 kHz, etc.

[0052] The term "parameter map" refers to the assignment of individual printing parameter values ​​(e.g. P(x,y,z)) to specific points (x,y,z) on the surface of an eyeglass lens substrate. These points can be defined by having similar "cost values" determined using a cost function and the surface geometry as input. The parameter map can be unique for each surface. The process of obtaining such a parameter map is called parameter mapping. For example, splitting an image using these specific points into, for example, eight sub-pictures that are printed with eight different sets of printing parameter values ​​P can be understood as parameter mapping.

[0053] The term "pose" is to be understood as meaning the combination of the position and orientation of the named object or component, e.g. a spectacle lens substrate or a print head, or a reference axis in three-dimensional space, see also ISO 8373:2021-11, section 5.5. According to this, the position of a mass point with respect to a Cartesian coordinate system is defined by the distance along the coordinate directions x, y, z. If a second Cartesian coordinate system is extended at this mass point, the orientation of the intersection of these coordinates is defined by the angular offset of its coordinate axes with respect to the corresponding axes of the base coordinate system. Three more angles are needed to describe the position of the new coordinate system with respect to the base coordinate system.

[0054] The term "print head" refers to the part of an inkjet printing device that carries the printing nozzles, and is preferably a single component. The print head may provide complete coverage of the surface to be printed, i.e. the entire surface to be printed can be printed in a single printing pass with one print head.

[0055] The term "print nozzle" refers to a nozzle of an inkjet printing device. A number of print nozzles are arranged in the print head of an inkjet printing device. During the ink ejection process, the print nozzle is filled with ink and the ink is ejected using shock waves resulting from piezoelectric actuation. Therefore, a specific voltage profile is applied to the print nozzle.

[0056] The term "print nozzle group" refers to one or more print nozzles that are commonly controlled with the same printing parameter values. A print nozzle group may cover only a portion of a surface to be printed in a single printing pass, i.e., print nozzles of at least two print nozzle groups may be required to print on the entire surface to be printed.

[0057] The term "printing parameters" refers to parameters of the printing process. Printing parameters are either adjustable printing parameters, i.e. essentially user adjustable, such as jetting frequency, jetting temperature, jetting duration, etc., or non-adjustable printing parameters, i.e. printing parameters that the user cannot adjust, such as print head geometry, number of print nozzles. Some printing parameters may be summarized as so-called gray levels, i.e. in this disclosure, instead of several printing parameters, gray levels can be considered as a common printing parameter.

[0058] The term "printing parameter value" refers to the parameter value of a printing parameter.

[0059] The term "printing process" refers to an inkjet printing process using drop-on-demand technology, i.e. a process for depositing ink droplets onto a substrate surface. A printing process can be described by printing parameters and respective printing parameter values.

[0060] The term "processor" refers to a functional unit in a computer that interprets and executes instructions. A processor may be part of a processing unit, which is a functional unit consisting of one or more processors and their internal storage (ISO / IEC 2382:2015).

[0061] The term "quality parameter" refers to a parameter describing the quality of an inkjet printing process, such as the number of satellite drops, the roundness of the printed dots, etc.

[0062] The term "single printing pass" refers to a printing process in which printing nozzles of at least two printing nozzle groups are used simultaneously to print a pattern on the surface of an eyeglass lens substrate. In other words, at least two printing nozzle groups are used in the same printing pass. A single printing pass may correspond to one printing or image layer, i.e., at least two printing nozzle groups may be used to print one printing or image layer.

[0063] The term "spectacle lens" refers to an ophthalmic lens that is worn in front of, but without contact with, the eye (ISO 13666:2019(E), clause 3.5.2), which is used for the purposes of measuring, correcting and / or protecting the eye or to change its appearance (ISO 13666:2019(E), clause 3.5.1).

[0064] The term "spectacle lens substrate" refers to an optical material used during the manufacturing process of a spectacle lens, for example a precursor of a finished spectacle lens, as well as the finished lens itself (ISO 13666:2019(E), section 3.8.9). A precursor of a finished lens is, for example, a lens blank, and the term "lens blank" refers to an optical material having an optically finished surface for the production of a lens (ISO 13666:2019(E), section 3.8.1) or a finished lens before cutting, and the term "finished lens before cutting" describes a finished lens before edging (ISO 13666:2019(E), section 3.8.8).

[0065] A surface is called "spherical" if it is part of the interior or exterior surface of a sphere (ISO 13666:2019(E), section 3.4.1), whereby its cross-section is circular for each meridian.

[0066] The term "storage medium" refers to a functional unit in which data can be stored, retained and from which they can be read (ISO / IEC 2382:2015).

[0067] The term "surface" refers to any layer of a three-dimensional spectacle lens substrate or a three-dimensional coated lens that is in direct contact with the environment. A surface can be considered as its boundary. Surfaces of a spectacle lens substrate include its front surface (ISO 13666:2019(E), clause 3.2.13), edge, and back surface (ISO 13666:2019(E), clause 3.2.14). Examples of surfaces of different shapes (surface types) are freeform progressive surfaces, freeform single vision surfaces, variable power surfaces, (as)pherical surfaces, cylindrical surfaces, and (a)toroidal surfaces. However, the invention is not limited to a specific surface type.

[0068] In the case of a spectacle lens, the expression "front surface" is used for the surface of the spectacle lens that is to be fitted to the opposite side of the eye (ISO 13666:2019(E), clause 3.8.13). In the case of a lens blank, the expression "front surface" is used for the surface that will eventually become the front surface of the spectacle lens produced from this lens blank. The curvature of a part of the front surface of the lens blank that is used as starting object for the production of a spectacle lens can already be close to the curvature of the spectacle lens to be produced.

[0069] With respect to spectacle lenses, the expression "rear surface" is used for the surface of the spectacle lens that will be fitted closer to the eye (ISO 13666:2019(E), clause 3.8.14). With respect to a lens blank, the expression "rear surface" is used for the surface that will eventually become the rear surface of the spectacle lens produced from this lens blank. The rear surface of a semi-finished lens blank may be machined during the manufacturing process of a spectacle lens.

[0070] The term "velocity vectors" refers to geometric objects, each having a magnitude or length and a direction, possibly referencing a particular reference point, that describe the velocity of movement of the eyeglass lens substrate and the print head relative to each other.

[0071] The term "virtual representation of a device" refers to a digital representation of a device (so-called digital twin), such as an implementation of the device with respective structural and / or analytical design features and / or numerical and / or analytical data sets (numerical and / or analytical representation) describing the design features. For example, such data sets may be stored in a computer memory or on a computer-readable (especially non-transient) storage medium. In addition, the data sets may be retrieved from a data network, such as the Internet or a local area network (LAN). A data set similar to a representation of a device may include any kind of features of the device, in particular descriptions of the structural features, materials of the units, etc. Such descriptions may include, for example, mathematical descriptions of the structural features of the device. The virtual representation may be in coded or encrypted form. The virtual representation of the device may additionally or alternatively include computer-readable instructions for controlling one or more manufacturing machines of the device to manufacture a physical device having the respective features.

[0072] The term "waveform parameter" refers to a printing parameter that describes the voltage profile applied to a printing nozzle, such as minimum voltage, maximum voltage, slope, duration of voltage application, etc. Typically, a voltage profile is described by multiple waveform parameters. With respect to the invention, one or more waveform parameters can be adjusted.

[0073] As used in this specification and the appended claims, the articles (a, an, and the) include the plural unless expressly and unambiguously restricted to the singular.

[0074] The term "and / or," as used herein, when used in a sequence of two or more elements, means that any of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, when the use of methods A, B, and / or C is described, only method A, only method B, only method C, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C may be used.

[0075] In a first aspect, the present invention provides a computer-implemented method for identifying printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, in particular a curved surface, The inkjet printing device includes a print head with a plurality of printing nozzles.

[0076] According to the invention, the method includes grouping a plurality of print nozzles into at least two print nozzle groups and individually identifying, e.g. calculating, a print parameter value for at least one adjustable print parameter for each print nozzle group, preferably at least two print nozzle groups to be used in a single printing pass.

[0077] The surface of the spectacle lens substrate may be a front surface or a rear surface. Moreover, it may be a spherical surface, an aspheric surface, a freeform surface, or any other type of surface, such as one of those mentioned above. The types of the front and rear surfaces may be the same or different from each other.

[0078] A print nozzle group may include a single print nozzle, i.e. only one print nozzle, several print nozzles, or multiple print nozzles. The number of print nozzle groups may vary from at least two print nozzle groups to a number of print nozzle groups equal to the number of print nozzles, i.e. each print nozzle group may include a single print nozzle. The smaller the number of print nozzle groups, the easier it is to identify and possibly optimize the corresponding print parameter values. An increased number of print nozzle groups may allow a better adaptation of the print parameter values ​​to the surface of the spectacle lens substrate, resulting in a better print result.

[0079] One basic idea of ​​the invention is based on the discovery that by individually optimizing the printing parameter values ​​for groups of printing nozzles or even for individual printing nozzles, the overall printing quality, measurable by parameters such as dot shape and impact area, can be significantly improved. In particular, the printing parameter values ​​can be individually specified and optimized for different relative positions of the print head and the spectacle lens substrate. Other or additional influencing factors that can affect the printing result can also be taken into account, such as, for example, anisotropic surface structure or surface hydrophobicity.

[0080] Moreover, the proposed method allows for improved printing patterns to be obtained in a single printing pass. In other words, there is no need to print different layers, which reduces time and production costs. Furthermore, only one printing head is needed, which further reduces time and production costs. Hardware arrangements for moving the spectacle lens substrate and / or the printing head can be omitted.

[0081] The proposed method can be used for any process in which the surface of a spectacle lens substrate is constructed, coated and / or surface / in-material modified using inkjet printing technology, e.g. coloring using coating or diffusion procedures, permanent or temporary lens marking, masking layers, adhesive layer spots, additive manufacturing, etc. This method is particularly interesting for the processing of spectacle lens substrates whose printing results can be optimized by "software", i.e. by the computer-implemented method of the present invention, instead of introducing complex positioning systems or robots to compensate for the average setting of printing parameters. Since the surface of a spectacle lens substrate usually has a unique shape, e.g. due to customized requirements, the proposed method allows high-speed printing with high printing quality and low equipment costs. The aforementioned method is widely applicable to a wide range of spectacle lens substrates that can be printed with high quality, thus allowing inkjet printing technology to be used for other applications during the production of spectacle lenses.

[0082] The at least one adjustable printing parameter can be selected from the group consisting of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink properties. Preferably, the printing parameter values ​​for a plurality of printing parameters can be specified individually, i.e. for each printing nozzle group. The fewer the number of printing parameters to be considered and the respective printing parameter values ​​to be specified, the easier their specification and possibly optimization will be. The more printing parameter values ​​to be specified, the better the printing process can be adapted to the surface of the spectacle lens substrate and the better the printing result can be obtained.

[0083] For example, the landing interval, i.e. the time between adjacent drops, is set by controlling the jetting frequency. At high jetting frequencies, the landing interval between adjacent drops is shorter than the solidification time of the drops. In contrast, at low jetting frequencies, the landing interval between adjacent drops is longer than the solidification time of the drops. As a result, there is no coalescence between adjacent drops. Printing parameter values ​​adapted based on the geometric characteristics of the eyeglass lens substrate and the print head result in a higher print quality with fewer satellites around the ink drops and less distortion of the ink drop shape.

[0084] In a particular development of the method of the invention, the method may comprise obtaining input data relating to the surface of the spectacle lens substrate and the geometric characteristics of the print head. The printing parameter values ​​can then be determined individually depending on the input data, i.e. the surface of the spectacle lens substrate and the geometric characteristics of the print head. By analyzing the geometric characteristics of the surface of the spectacle lens substrate to be printed, in particular the surface curvature, and the geometric characteristics of the print head, the geometric relationship between the spectacle lens substrate and the print head can be inferred during the printing process. In other words, the input data can be used to determine the geometric relationship between the surface of the spectacle lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an incidence angle α, a distance or an arc length s. At least one, preferably several or even all of the parameters describing the geometric relationship can be selected and used for the individual determination of the printing parameter values.

[0085] Taking this geometrical relationship into account, a detailed and optimized printing parameter value for at least one printing parameter can be determined, for example calculated, for each nozzle or nozzle group of the print head. In other words, the printing parameter value can be determined for a geometrical feature, whereby the printing quality on curved surfaces can be improved by controlling each printing nozzle group individually. No complex positioning system or robot is required to compensate for the average setting of the printing parameters by positioning the spectacle lens substrate and the print head relative to each other. Furthermore, the use of a print head having a non-flat surface, i.e. a flat surface on which the printing nozzles are located, can be facilitated.

[0086] The input data can be obtained, for example, by receiving it by wired or wireless transfer from a storage unit for storing the geometrical characteristics of different spectacle lens substrates and / or print heads. Another possibility is to input the geometrical characteristics manually or automatically using an input unit coupled to a data processing system which executes the method of the invention. The geometrical characteristics can be provided, for example, in the form of tabulated values ​​or the geometrical characteristics can be measured and processed directly using a suitable measuring system. Combinations thereof can also be used.

[0087] Apart from the geometric characteristics of the spectacle lens substrate and the print head, the input data may include data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the spectacle lens substrate.

[0088] By taking these additional influence factors into account when determining the printing parameter values, the printing process can be adapted even better to the overall conditions and the printing result can be further improved. For example, these additional influence factors can be taken into account when estimating at least one parameter map as described below, i.e. the parameter map not only describes the geometric relationship between the spectacle lens substrate and the print head during the printing process, but also includes other influence factors that may affect the printing process.

[0089] In another particular development of the method of the present invention, the method step of individually determining printing parameter values ​​for at least one adjustable printing parameter may comprise a step of estimating a parameter map comprising an assignment of printing parameter values ​​to specific points on the surface of the eyeglass lens substrate.

[0090] To infer the parameter map, known geometric features describing the surface of the spectacle lens substrate, e.g. as part of the input data, e.g. the actual front curve diameter, can be used to convert the surface into a grid or mesh of data points. These data points can then be looped through to look up the actual settings, i.e. the set of printing parameter values, in a pre-created universal lookup table. The lookup table may contain optimized printing parameter values ​​for a particular data point and a particular print head, i.e. a particular geometric relationship between the spectacle lens substrate and the print head. One and the same data point stored in this lookup table may be present on many different surfaces.

[0091] The estimated parameter maps can form a basic reference system for optimizing the complete printing parameter space, for example optimizing the dot shape or weight of ink droplets as a function of incidence angle, nozzle-substrate distance, print head velocity vector, firing frequency, and firing duration.

[0092] For example, the parameter map may be inferred by optimizing a cost function applied to a correlation between parameters describing the geometric relationship between the surface of the eyeglass lens substrate and the print head and printing parameter values ​​of adjustable printing parameters, e.g., a correlation stored in a look-up table.

[0093] The optimization of the cost function can be performed using at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. For example, the so-called Broyden-Fletcher-Goldfarb-Shanno algorithm can be used for the optimization.

[0094] Furthermore, machine learning processes can be used in the optimization, which may make it possible to detect and take into account further influencing factors whose impact is not currently taken into account.

[0095] In another particular development of the method according to the invention, a printing parameter value of at least one adjustable printing parameter of each printing nozzle group can be determined individually, whereby a printing parameter value of the ... Against There is no need to adjust the print head tilt angle before and / or during printing.

[0096] For example, the surface to be printed and the surface of the print head, including the multiple nozzles, may be oriented essentially parallel throughout the printing process.

[0097] This avoids the need for complex hardware arrangements for rotating, e.g. mechanically tilting, the spectacle lens substrate and / or the print head before and / or during printing, which would otherwise be necessary to optimize the printing result. The effects achieved by complex hardware arrangements such as prior art tilting devices can be mimicked solely by completely individualized printing parameter values, i.e. individualized ejection profiles for groups of printing nozzles.

[0098] Depending on the size of the print head and the printing surface, i.e. if the size of the print head is such that it can cover the entire printing surface, the pose, i.e. the position and orientation, of both the spectacle lens substrate and the print head can remain constant relative to each other while printing a pattern on the surface of the spectacle lens substrate. In other words, an improved pattern can be obtained by simply adjusting the printing parameter values ​​of one or more adjustable printing parameters, without moving the spectacle lens substrate and the print head relative to each other. This may allow for an even more simplified hardware arrangement.

[0099] According to another aspect of the present invention, there is provided a data processing system including a processor and a storage medium coupled to the processor, the processor adapted to determine printing parameter values ​​for an inkjet printing device including a printhead with a plurality of printing nozzles for printing a pattern on a surface of an eyeglass lens substrate based on a computer program stored on the storage medium.

[0100] The processor is adapted to group the plurality of print nozzles into at least two print nozzle groups and to separately identify a print parameter value for at least one adjustable print parameter for each print nozzle group, preferably at least two print nozzle groups to be used in a single printing pass.

[0101] In other words, the data processing system is configured to execute one of the computer-implementable methods for identifying printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate as described above. Therefore, please refer to the above description describing the computer-implemented method for identifying printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate and its advantages.

[0102] In a particular development, the processor is adapted to determine the printing parameter values ​​individually as a function of the geometric characteristics of the spectacle lens substrate and of the print head.

[0103] According to another aspect of the invention, there is provided a computer program comprising instructions which, when executed by a computer, cause the computer to determine print parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head with a plurality of print nozzles. The instructions cause the computer to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​for at least one adjustable print parameter for each print nozzle group separately. Preferably, the at least two print nozzle groups are to be used in a single printing pass.

[0104] In other words, the computer program includes instructions for carrying out one of the computer-implemented methods for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate as described above. Therefore, please refer to the above description describing the computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate and its advantages.

[0105] According to another aspect of the invention, a non-transitory computer readable storage medium is provided that includes instructions that, when executed by a computer, cause the computer to determine print parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head with a plurality of print nozzles. The instructions cause the computer to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​for at least one adjustable print parameter for each print nozzle group separately. Preferably, the at least two print nozzle groups are to be used in a single printing pass.

[0106] In other words, the non-transitory computer-readable storage medium includes instructions for performing one of the computer-implemented methods for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate as described above. Therefore, please refer to the above description describing the computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate and its advantages.

[0107] According to another aspect of the invention, there is provided an inkjet printing method, in which a pattern is printed on a surface of an eyeglass lens substrate by an inkjet printing device including a print head with a plurality of print nozzles using printing parameter values ​​of at least one adjustable printing parameter, the printing parameter values ​​of the at least one adjustable printing parameter being determined according to the computer-implemented method described above.

[0108] In other words, a computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate, the method comprising the steps of grouping the printing nozzles into printing nozzle groups and individually determining the printing parameter value of at least one adjustable printing parameter for each printing nozzle group, whereby after determining the printing parameter value of the at least one adjustable printing parameter, actual printing can be performed using the determined printing parameters. Therefore, please refer to the above description of the computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate and its advantages. The inkjet printing method can be used, for example, for coloring using a coating or diffusion procedure, permanent or temporary lens marking, masking layers, e.g. adhesive layer spots that increase the surface roughness for the application of a coating, additive manufacturing, etc.

[0109] In a particular development of the inkjet printing method, the surface of the spectacle lens substrate is Against The print head tilt angle is not adjusted before and / or during printing.

[0110] For example, the printing surface and the surface of the print head, including the printing nozzles, may be oriented essentially parallel throughout the printing process.

[0111] This eliminates the need for complex hardware arrangements for rotating, e.g. mechanically tilting, the spectacle lens surface and / or the print head before and / or during printing, which would otherwise be necessary to optimize the printing result. The effects achieved by complex hardware arrangements such as prior art tilting devices can be mimicked solely by completely individualized printing parameter values, i.e. individualized ejection profiles for groups of printing nozzles.

[0112] Depending on the size of the print head and the printing surface, i.e. if the size of the print head is such that it can cover the entire printing surface, the pose, i.e. the position and orientation, of both the spectacle lens substrate and the print head can remain constant relative to each other while printing the pattern on the surface of the spectacle lens substrate. In other words, an improved pattern can be obtained without moving the spectacle lens substrate and the print head relative to each other, by only adjusting the print parameter values ​​of one or more adjustable print parameters. This may allow for a much more simplified hardware arrangement. According to another aspect of the present invention, an inkjet printing device for printing a pattern on the surface of a spectacle lens substrate is provided. The inkjet printing device includes a print head with a plurality of print nozzles, and a data processing system including a processor and a storage medium coupled to the processor, the processor being adapted to determine the print parameters based on a computer program stored in the storage medium. The processor is adapted to group the plurality of print nozzles into at least two print nozzle groups and to determine separately the print parameter value of at least one adjustable print parameter for each print nozzle group. Preferably, the at least two print nozzle groups will be used within a single printing pass.

[0113] The inkjet printing device is configured to carry out the inkjet printing method described above, therefore reference is made to the above description which describes the inkjet printing method in which a pattern is printed on the surface of a spectacle lens substrate and its advantages.

[0114] According to another aspect of the invention, there is provided a data set in the form of a computer readable data signal that includes at least one of the following types of data: (i) a virtual representation of an inkjet printing device as described above configured to be supplied to one or more manufacturing machines to manufacture the device; or (ii) data including computer readable instructions to control one or more manufacturing machines to manufacture the inkjet device as described above.

[0115] According to another aspect of the invention, a data set in the form of a computer-readable data carrier signal is provided, the data set comprising at least one of the following types of data: (i) printing parameter values ​​of at least one adjustable printing parameter individual for at least two printing nozzle groups of an inkjet printing device comprising a print head with a plurality of printing nozzles, configured to be supplied to an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, or (ii) data comprising computer-readable instructions for controlling an inkjet printing device to print a pattern on a surface of an eyeglass lens substrate by applying individual printing parameter values ​​of the at least one adjustable printing parameter to at least two printing nozzle groups of an inkjet printing device comprising a print head with a plurality of printing nozzles.

[0116] The dataset can be used to perform the aforementioned inkjet printing method, i.e. a method in which a pattern is printed on a surface of an eyeglass lens substrate using printing parameter values ​​of at least one adjustable printing parameter in an inkjet printing device including a print head with a plurality of printing nozzles.

[0117] The data is obtained by executing a computer-implemented method for identifying printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of said spectacle lens substrate, and therefore reference is made to the above description which describes this method and its advantages.

[0118] According to another aspect of the invention, a computer-implemented method for determining print parameter values ​​of an inkjet printing device for printing a pattern on a curved surface of an eyeglass lens surface is provided, the inkjet printing device including a print head with a plurality of print nozzles. The method includes the steps of obtaining input data relating to a surface of an eyeglass lens substrate and a geometric characteristic of the print head, the input data being used to determine a geometric relationship between the surface of the eyeglass lens substrate and the print head, grouping the plurality of print nozzles into at least two print nozzle groups, and determining print parameter values ​​of at least one adjustable print parameter of each print nozzle group individually according to the geometric relationship. Preferably, the at least two print nozzle groups will be used within a single printing pass.

[0119] The surface of the spectacle lens substrate may be a front surface or a rear surface. Moreover, it may be a spherical surface, an aspheric surface, a freeform surface, or any other surface type, such as one of those mentioned above. The surface types of the front and rear surfaces may be the same or different from each other.

[0120] A print nozzle group may include a single print nozzle, i.e. only one print nozzle, several print nozzles, or multiple print nozzles. The number of print nozzle groups may vary from at least two print nozzle groups to a number of print nozzle groups equal to the number of print nozzles, i.e. each print nozzle group may include a single print nozzle. The smaller the number of print nozzle groups, the easier it is to identify and possibly optimize the corresponding print parameter values. An increased number of print nozzle groups may allow a better adaptation of the print parameter values ​​to the surface of the spectacle lens substrate, resulting in a better print result.

[0121] One basic idea of ​​the invention is based on the discovery that by individually optimizing the printing parameter values ​​for groups of printing nozzles and even for individual printing nozzles, the overall printing quality, measurable by parameters such as dot shape and impact area, can be significantly improved. In particular, the printing parameter values ​​can be individually identified and optimized for various relative positions of the printing head and the spectacle lens substrate. Other or additional influencing factors that can affect the printing result, such as anisotropic surface structures or surface hydrophobicity, can also be taken into account. Furthermore, the use of printing heads with non-flat surfaces, i.e. flat surfaces on which the printing nozzles are arranged, can be facilitated.

[0122] Moreover, the proposed method allows for improved printing patterns to be obtained in a single printing pass. In other words, there is no need to print different layers, which reduces time and production costs. Furthermore, only one printing head is needed, which further reduces time and production costs. Hardware arrangements for moving the spectacle lens substrate and / or the printing head can be omitted.

[0123] The proposed method can be used for any process in which the surface of a spectacle lens substrate is constructed, coated and / or surface / in-material modified using inkjet printing technology, e.g. coloring using coating or diffusion procedures, permanent or temporary lens marking, masking layers, adhesive layer spots, additive manufacturing, etc. This method is particularly interesting for the processing of spectacle lens substrates whose printing results can be optimized by "software", i.e. by the computer-implemented method of the present invention, instead of introducing complex positioning systems or robots to compensate for the average setting of printing parameters. Since the surface of a spectacle lens substrate usually has a unique shape, e.g. due to customized requirements, the proposed method allows high-speed printing with high printing quality and low equipment costs. The aforementioned method is widely applicable to a wide range of spectacle lens substrates that can be printed with high quality, thus allowing inkjet printing technology to be used for other applications during the production of spectacle lenses.

[0124] The at least one adjustable printing parameter can be selected from the group consisting of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink properties. Preferably, the printing parameter values ​​for a plurality of printing parameters can be specified individually, i.e. for each printing nozzle group. The fewer the number of printing parameters to be considered and the respective printing parameter values ​​to be specified, the easier their specification and possibly optimization will be. The more printing parameter values ​​to be specified, the better the printing process can be adapted to the surface of the spectacle lens substrate and the better the printing result can be obtained.

[0125] For example, the landing interval, i.e. the time between adjacent drops, is set by controlling the jetting frequency. At high jetting frequencies, the landing interval between adjacent drops is shorter than the solidification time of the drops. In contrast, at low jetting frequencies, the landing interval between adjacent drops is longer than the solidification time of the drops. As a result, there is no coalescence between adjacent drops. Printing parameter values ​​adapted based on the geometric characteristics of the eyeglass lens substrate and the print head result in a higher print quality with fewer satellites around the ink drops and less distortion of the ink drop shape.

[0126] By analyzing the geometric characteristics, in particular the surface curvature of the surface of the spectacle lens substrate to be printed, and the geometric characteristics of the print head, the geometric relationship between the spectacle lens substrate and the print head during the printing process can be derived. In other words, the input data is used to determine the geometric relationship between the surface of the spectacle lens substrate and the print head.

[0127] The geometric relationship may be described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an incidence angle α, a distance Δ, and an arc length s. Thus, at least one of the parameters describing the geometric relationship may be used to individually identify a printing parameter value for at least one adjustable printing parameter of each printing nozzle group. At least one, preferably multiple, or even all of the parameters describing the geometric relationship may be selected and used for the individual identification of the printing parameter value.

[0128] Taking this geometric relationship into account, for each nozzle or nozzle group of the marking print head, individually detailed and optimized printing parameter values ​​for at least one printing parameter can be specified, for example calculated. In other words, printing parameter values ​​are specified for geometric features, whereby the printing quality on curved surfaces can be improved by individually controlling each printing nozzle group. By positioning the spectacle lens substrate and the print head relative to each other, no complex positioning systems or robots are required to compensate for the average setting of the printing parameters.

[0129] The input data can be obtained, for example, by receiving it by wired or wireless transfer from a storage unit for storing the geometrical characteristics of different spectacle lens substrates and / or print heads. Another possibility is to input the geometrical characteristics manually or automatically using an input unit coupled to a data processing system which executes the method of the invention. The geometrical characteristics can be provided, for example, in the form of tabulated values ​​or the geometrical characteristics can be measured and processed directly using a suitable measuring system. Combinations thereof can also be used.

[0130] Optionally, the input data may include data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate, and thus the print parameter values ​​of the at least one adjustable print parameter of each print nozzle group may be individually determined depending on the input data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate.

[0131] By taking these additional influence factors into account when determining the printing parameter values, the printing process can be adapted even better to the overall conditions and the printing result can be further improved. For example, these additional influence factors can be taken into account when estimating at least one parameter map as described below, i.e. the parameter map not only describes the geometric relationship between the spectacle lens substrate and the print head during the printing process, but also includes other influence factors that may affect the printing process.

[0132] In a particular development, the method step of individually determining printing parameter values ​​for the at least one adjustable printing parameter may comprise estimating a parameter map comprising an assignment of printing parameter values ​​to data points on a surface of the spectacle lens substrate. The step of estimating the parameter map may comprise transforming the surface of the spectacle lens substrate into a grid of data points.

[0133] The method step of individually identifying printing parameter values ​​for the at least one adjustable printing parameter may also include providing a look-up table including correlations between parameters describing a geometric relationship between the surface of the eyeglass lens substrate and the print head and printing parameter values ​​for the adjustable printing parameters. Individually identifying the printing parameter values ​​may include retrieving a set of printing parameter values ​​from the look-up table for the data point.

[0134] Optionally, the parameter map may be estimated by optimizing a cost function applied to the correlation between parameters describing the geometric relationship between the surface of the eyeglass lens substrate and the print head and printing parameter values ​​of the adjustable printing parameters.

[0135] In other words, for each parameter or combination thereof that describes the geometric relationship between the surface of the spectacle lens substrate and the print head, a specific set of printing parameter values ​​can be assigned. Input data regarding environmental conditions and material properties can be taken into account when creating the look-up table. The look-up table can contain printing parameter values ​​optimized for a specific data point and a specific print head, i.e. a specific geometric relationship between the spectacle lens substrate and the print head. One and the same data point stored in this look-up table can be on many different surfaces.

[0136] To infer the parameter map, known geometric features describing the surface of the spectacle lens substrate, e.g. as part of the input data, e.g. the actual front curve diameter, can be used to convert the surface into a grid or mesh of data points that can then be looped through to find the actual settings, i.e. the set of printing parameter values, in a pre-created universal lookup table.

[0137] The estimated parameter maps can form a fundamental reference system for optimizing the complete printing parameter space, for example optimizing the dot shape or weight of ink droplets as a function of incidence oblique angle, nozzle-substrate distance, print head velocity vector, firing frequency, and firing duration.

[0138] For example, the parameter map may be inferred by optimizing a cost function applied to correlations between parameters describing the geometric relationship between the surface of the eyeglass lens substrate and the print head and printing parameter values ​​of adjustable printing parameters, e.g. correlations stored in a look-up table.

[0139] The optimization of the cost function can be performed using at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. For example, the so-called Broyden-Fletcher-Goldfarb-Shanno algorithm can be used for the optimization.

[0140] Furthermore, machine learning processes can be used in the optimization, which may make it possible to detect and take into account further influencing factors whose impact is not currently taken into account.

[0141] In another particular development, the printing parameter values ​​of the at least one adjustable printing parameter of each printing nozzle group can be determined individually, whereby a printing parameter value ... Against There is no need to adjust the print head tilt angle before and / or during printing.

[0142] For example, the surface to be printed and the surface of the print head, including the multiple nozzles, may be oriented essentially parallel throughout the printing process.

[0143] This avoids the need for complex hardware arrangements for rotating, e.g. mechanically tilting, the spectacle lens substrate and / or the print head before and / or during printing, which would otherwise be necessary to optimize the printing result. The effects achieved by complex hardware arrangements such as prior art tilting devices can be mimicked solely by completely individualized printing parameter values, i.e. individualized ejection profiles for groups of printing nozzles.

[0144] Depending on the size of the print head and the printing surface, i.e. if the size of the print head is such that it can cover the entire printing surface, the pose, i.e. the position and orientation, of both the spectacle lens substrate and the print head can remain constant relative to each other while printing a pattern on the surface of the spectacle lens substrate. In other words, an improved pattern can be obtained by simply adjusting the printing parameter values ​​of one or more adjustable printing parameters, without moving the spectacle lens substrate and the print head relative to each other. This may allow for an even more simplified hardware arrangement.

[0145] According to another aspect of the present invention, there is provided a data processing system including a processor and a storage medium coupled to the processor, the processor being adapted to determine printing parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head with a plurality of printing nozzles based on a computer program stored on the storage medium.

[0146] The processor is adapted to group the plurality of print nozzles into at least two print nozzle groups and to individually determine a print parameter value for the at least one adjustable print parameter for each print nozzle group as a function of a geometric relationship between a surface of the spectacle lens substrate and the print head, the geometric relationship being determined using input data relating to geometric characteristics of the surface of the spectacle lens substrate and the print head. Preferably, the at least two print nozzle groups are to be used in a single printing pass.

[0147] In other words, the data processing system is configured to execute one of the computer-implementable methods for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate, the printing parameter values ​​being determined individually depending on the geometric relationship between the surface of the spectacle lens substrate and the print head. Therefore, please refer to the above description describing this computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate and its advantages.

[0148] According to another aspect of the invention, a computer program is provided that includes instructions that, when executed by a computer, cause the computer to determine print parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head with a plurality of print nozzles. The instructions cause the computer to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​for at least one adjustable print parameter for each print nozzle group separately depending on a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being determined using data input related to geometric characteristics of the surface of the eyeglass lens substrate and the print head. Preferably, at least two print nozzle groups are to be used within a single printing pass.

[0149] In other words, the computer program includes instructions for performing one of the computer-implemented methods for determining printing parameter values ​​of an inkjet printing device for printing a pattern on the surface of a spectacle lens substrate, the printing parameter values ​​being determined individually depending on the geometric relationship between the surface of the spectacle lens substrate and the print head as described above. Therefore, please refer to the above description describing this computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on the surface of a spectacle lens substrate and its advantages.

[0150] According to another aspect of the invention, a non-transitory computer-readable storage medium is provided that includes instructions that, when executed by a computer, cause the computer to determine print parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head with a plurality of print nozzles. The instructions cause the computer to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​for at least one adjustable print parameter for each print nozzle group separately depending on a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being determined using input data related to geometric characteristics of the surface of the eyeglass lens substrate and the print head. Preferably, the at least two print nozzle groups are to be used within a single printing pass.

[0151] In other words, the non-transitory computer-readable storage medium includes instructions for performing one of the computer-implemented methods for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate, and the printing parameter values ​​are determined individually depending on the geometric relationship between the surface of the spectacle lens substrate and the print head as described above. Therefore, please refer to the above description of the computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate and its advantages.

[0152] According to another aspect of the invention, there is provided an inkjet printing method, in which a pattern is printed on a surface of an eyeglass lens substrate by an inkjet printing device including a print head with a plurality of print nozzles using print parameter values ​​of at least one adjustable print parameter, the print parameter values ​​of the at least one adjustable print parameter being determined according to a computer-implemented method, the print parameter values ​​being determined individually depending on a geometric relationship between the surface of the eyeglass lens substrate and the print head as previously described.

[0153] In other words, a computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate, the method comprising the steps of grouping the printing nozzles into printing nozzle groups and determining printing parameter values ​​of at least one adjustable printing parameter for each printing nozzle group individually depending on the geometric relationship between the surface of the spectacle lens substrate and the printing head, whereby after determining the printing parameter values ​​of the at least one adjustable printing parameter, actual printing can be performed using the determined printing parameter values. Therefore, please refer to the above description of the computer-implemented method for determining printing parameter values ​​of an inkjet printing device for printing a pattern on a surface of a spectacle lens substrate, the printing parameter values ​​being determined individually depending on the geometric relationship between the surface of the spectacle lens substrate and the printing head, and its advantages. The inkjet printing method can be used, for example, for coloring using a coating or diffusion procedure, for permanent or temporary lens marking, for masking layers, for example adhesive layer spots that increase the surface roughness for the application of a coating, for additive manufacturing, etc.

[0154] In a particular development of the inkjet printing method, the surface of the spectacle lens substrate is Against The print head tilt angle is not adjusted before and / or during printing.

[0155] For example, the printing surface and the surface of the print head, including the printing nozzles, may be oriented essentially parallel throughout the printing process.

[0156] This eliminates the need for complex hardware arrangements for rotating, e.g. mechanically tilting, the spectacle lens surface and / or the print head before and / or during printing, which would otherwise be necessary to optimize the printing result. The effects achieved by complex hardware arrangements such as prior art tilting devices can be mimicked solely by completely individualized printing parameter values, i.e. individualized ejection profiles for groups of printing nozzles.

[0157] Depending on the size of the print head and the printing surface, i.e. if the size of the print head is such that it can cover the entire printing surface, the pose, i.e. the position and orientation, of both the spectacle lens substrate and the print head can remain constant relative to each other while printing a pattern on the surface of the spectacle lens substrate. In other words, an improved pattern can be obtained by simply adjusting the printing parameter values ​​of one or more adjustable printing parameters, without moving the spectacle lens substrate and the print head relative to each other. This can lead to a much simplified hardware arrangement.

[0158] According to another aspect of the present invention, there is provided an inkjet printing apparatus for printing a pattern on a surface of an eyeglass lens substrate. The inkjet printing apparatus includes a print head with a plurality of print nozzles, and a data processing system including a processor and a storage medium coupled to the processor, the processor being adapted to determine print parameter values ​​based on a computer program stored on the storage medium. The processor is adapted to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​of at least one adjustable print parameter for each print nozzle group individually depending on a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being determined using input data relating to geometric characteristics of the surface of the eyeglass lens substrate and the print head. Preferably, at least two print nozzle groups will be used within a single printing pass.

[0159] The inkjet printing device is configured to carry out the inkjet printing method described above, therefore reference is made to the above description which describes the inkjet printing method in which a pattern is printed on the surface of a spectacle lens substrate and its advantages.

[0160] According to another aspect of the invention, there is provided a data set in the form of a computer readable data signal that includes at least one of the following types of data: (i) a virtual representation of an inkjet printing device as described above configured to be supplied to one or more manufacturing machines to manufacture the device; or (ii) data including computer readable instructions to control one or more manufacturing machines to manufacture the inkjet device as described above.

[0161] Other features, characteristics, and advantages of the present invention will become apparent from the following description of the embodiments taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0162] [Figure 1] 1 shows a schematic diagram of a prior art inkjet printhead moving over the curved surface of an eyeglass lens substrate during the printing process. [Diagram 2] 1 shows a plan view from below of a printhead with multiple print nozzles according to the prior art; [Diagram 3] 1 shows a typical voltage profile applied to the nozzles of a prior art inkjet printhead. [Figure 4] 1 shows a schematic view of the surface of a spectacle lens substrate (cross-sectional view cut in half). [Diagram 5] Schematic diagram of a print head passing over the surface of an eyeglass lens substrate (top view). [Figure 6] Figure 5 shows the discretized x,y,z positions of the points forming the front surface of an eyeglass lens substrate with parameters D=50.0 mm, r=425.0 mm. The three arrows indicate the x,y paths during the printing process of the three single print head nozzles shown in Figure 5. [Figure 7] 6 shows the calculated height difference between the three printing nozzles shown in FIG. 5 and the surface of the eyeglass lens substrate during the printing process. [Figure 8]Figure 5 shows the incidence angle α(x,y,z) between the normal vector n(x,y,z) of the front surface of an eyeglass lens substrate with parameters D=50.0 mm and r=425.0 mm and the incidence inkjet (0,0,-1) of the three printing nozzles shown in Figure 5. [Figure 9] 6 shows the angles of incidence along the paths of each of the three print nozzles shown in FIG. 5. [Figure 10] 4 is a flow chart illustrating an embodiment of a computer-implemented method for determining printing parameter values. [Figure 11] 1 shows a schematic representation of a print head with a group of print nozzles. [Figure 12] 5 is a flow chart illustrating another embodiment of a computer-implemented method for determining printing parameter values. [Figure 13] 4 shows a block diagram of yet another embodiment of a computer-implemented method for determining printing parameter values. [Figure 14] 1 illustrates a schematic diagram of an embodiment of an inkjet printing device. [Figure 15] 1 shows a Recon image of a printed curved surface of an eyeglass lens substrate with a recognized contour diameter of 65 mm. [Figure 16] Shows another Recon image of a printed curved surface, with the nozzle array data loaded onto the wax pattern overlaid. [Figure 17] 1 shows an original microscope image of tile number 5 with a surface printed with a norm value of 50. [Figure 18] 18 shows a black and white thresholded microscope image obtained from the image shown in FIG. 17. [Figure 19] In Figure 17, a microscope image is shown with the main features and satellites marked. [Figure 20] The average circularity of the main features is shown as a function of the equivalent radius and the applied norm value. [Figure 21] Indicates the number of satellites per tile depending on the equivalent radius and the norm value applied. [Figure 22] 1 shows a graphical representation of the cost function depending on the equivalent radius and the norm value applied. [Diagram 23] 13 shows a graphical representation of other cost functions depending on the equivalent radius and the norm value applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0163] 1 shows the technical problem underlying the present invention: a pattern is to be printed on a curved surface 3 of a spectacle lens substrate 4 by means of an inkjet printing device comprising a print head 2 with a number of print nozzles 6. The print nozzles 6 eject droplets 9 of ink, which are deposited on the surface 3 of the spectacle lens substrate 4.

[0164] A typical print head 2 as shown in Figure 2 may include, for example, 880 print nozzles 6 arranged at specific intervals in multiple columns and rows. For example, 300 print nozzles 6 may be arranged every inch in the x-direction, resulting in a printing resolution or pixel density of 300 dots per inch (dpi) each.

[0165] According to the prior art, all print nozzles are controlled uniformly, i.e. the same print parameter value 1 for the adjustable print parameter 8 is used for all print nozzles 6. This results in a uniform printed image as long as the surface 6 of the spectacle lens substrate 4 is uniform, for example flat. However, if the surface 6 of the spectacle lens substrate 4 is not uniform, for example presents a curved surface 6 as shown in FIG. 1, the printing result is adversely affected. This is due to different distances Δ 1 , Δ 2 Typically, the minimum distance Δ between the printing nozzle 6 and the surface 3 of the spectacle lens substrate 4 1 is less than 5 mm. Its relative position-dependent value Δ 2 varies and typically increases towards the outer portions of the spectacle lens substrate 4.

[0166] Figure 3 shows a typical voltage profile applied to the print nozzles 6 during the printing process. Several phases can be distinguished: rest phase, prefill phase, ejection phase, refill / cancel phase. According to the prior art, the same voltage profile is applied to all print nozzles. The voltage profile can be modified in order to adjust the printing process and to influence the overall print quality. For example, for each phase the minimum and maximum voltages, the slope and / or the duration can be modified. Printing parameters 8 that can be adjusted by modifying the voltage profile are the ejection frequency, the waveform and the norm.

[0167] FIG. 4 shows a schematic representation of a curved surface 3 of an eyeglass lens substrate 4 in a cross-section cut in half, where n is the normal vector at any point of the surface 3, j is the ejection vector along which the ejected ink is transferred from the print nozzle 6 to the surface 3, α is the angle of incidence between the normal vector n and the ejection vector j, r is the true front curve (true radius of curvature) of the surface 3 obtained from a sphere, dx, dy (not shown in FIG. 4) and dz are the differences discretized in the coordinate system used, and s is the approximate arc length between two points on the surface 3.

[0168] FIG. 5 shows, in a top view, the surface 3 of a spectacle lens substrate 4 of diameter D together with the movement paths in the x,y-direction of three different printing nozzles 6a, 6b, 6c of a printing head 5 during the printing process, i.e. as the printing head 5 and the surface 3 move linearly relative to each other along the movement direction m.

[0169] With reference to Figures 6-9, the effects associated with printing on the exemplary surface 3 shown in Figures 4 and 5 are further described. The exemplary ejection vector j is selected to be 0, 0, -1. Figure 6 shows the discretized x, y, z positions of the points forming the front surface 3 of the spectacle lens substrate 4 with parameters D = 50.0 mm, r = 425.0 mm. The three arrows show the x, y paths of the three single printing nozzles 6a, 6b, 6c shown in Figure 5 during the printing process. The z positions are represented in Figure 6 by numbers ranging from 424.150 to 424.900. It should be noted, however, that the z positions change gradually, which cannot be shown in Figure 6 due to the formal requirements of the drawing. Therefore, the annotated numerical values ​​of the z positions are only an example to represent the general course of the z positions.

[0170] Figure 7 shows the corresponding calculated height profile between the printing nozzles 6a, 6b, 6c and the surface 3 during the printing process, i.e. the z-position along the arrows in Figure 6. The minimum distance Δ 1 is 1mm.

[0171] As can be seen from figures 6 and 7, the height difference along the path of the print nozzle 6a is much larger than for the print nozzles 6b, 6c. This leads to inconsistent printing results, i.e. the overall print quality, when optimized for the centre of the surface 3, degrades significantly towards the edge of the spectacle lens substrate 4.

[0172] FIG. 8 shows the discretized x,y positions of the points forming the front surface 3 of the spectacle lens substrate 4 with parameters D=50.0 mm, r=425.0 mm. The three arrows show the x,y paths of the three single printing nozzles 6a, 6b, 6c shown in FIG. 5 during the printing process. The incidence angles α at different x,y positions are represented in FIG. 8 by numerical values ​​ranging from 0.400 to 3.600. It should be noted, however, that the incidence angles α vary gradually, which cannot be shown in FIG. 8 due to the formal requirements of the drawing. Therefore, the annotated numerical values ​​of the incidence angles α are only examples to represent the general course of the incidence angles α. FIG. 9 shows the incidence angles α depending on the x position of the printing nozzles 6a, 6b, 6c, i.e. along the arrows in FIG. 8. The incidence angles α vary between 0° and more than 3.5°, the deviation being much larger for the printing nozzle 6a compared to the printing nozzles 6b, 6c. In general, the incidence angles α increase towards the edge of the spectacle lens substrate 4. This amplifies the inconsistent printing results already caused by the height differences described with respect to Figures 6 and 7, i.e. the overall print quality, when optimized for the centre of the surface 3, degrades even more towards the edge of the lens substrate 4.

[0173] As the distance Δ between the printing nozzle 6 and the surface 3 of the spectacle lens substrate 4 increases and the angle of incidence α increases, the inventors of the present invention have observed a clear tendency towards a scattered print result, i.e. a large number of small dots.

[0174] In order to reduce the aforementioned adverse effects on print quality, a computer-implemented method 100 is proposed for determining print parameter values ​​1 of an inkjet printing device 2 for printing a pattern on a surface 3 of a spectacle lens substrate 4. The inkjet printing device 2 comprises a print head 5 equipped with a number of print nozzles 6. The flow chart shown in Fig. 10 relates to a first embodiment of such a method 100.

[0175] In a first step S1, input data 8 are obtained relating to the geometric characteristics of the surface 3 of the spectacle lens substrate 4 and the print head 5 of the inkjet printing device 2. This data may include data relating to the topology of the surface 3 of the spectacle lens substrate 4, such as its diameter D, its true front curve r, and geometric data relating to the print head 5, such as its orientation, the number of print nozzles 6, the spacing of the print nozzles 6, etc. For example, the diameter D is 50 mm and the true radius of curvature r is 425.0 mm. The print head 5 may include 880 print nozzles 6, with a nozzle spacing of 300 per inch in the x-direction.

[0176] In step S2, the plurality of print nozzles 6 are grouped into five print nozzle groups 10a, 10b, 10c, 10d, 10e. The exact number of print nozzle groups 10a, 10b, 10c, 10d, 10e may vary depending on the geometric characteristics of the spectacle lens substrate 4 and / or the required print quality. At least two of the five print nozzle groups 10a, 10b, 10c, 10d, 10 will be used in a single printing pass. Optionally, all of the print nozzle groups 10a, 10b, 10c, 10d, 10 will be used in a single printing pass.

[0177] Figure 11 shows a print head 5, which is grouped into five print nozzle groups 10a, 10b, 10c, 10d, 10e arranged symmetrically with respect to the movement direction m of the print head 5. Towards the edges are arranged the two print nozzle groups 10a, 10e which contain the smallest number of print nozzles 6. Closer to the centre are arranged the two print nozzle groups 10b, 10d which contain more print nozzles 6. The central print nozzle group 10c contains the largest number of print nozzles 6. This number of print nozzle groups 10a, 10b, 10c, 10d, 10e and their arrangement are obtained from the course of the height difference and the incidence angle α shown in Figures 7 and 9, which are steep towards the edges and flat in the centre.

[0178] 10, in step S3, printing parameter values ​​1 for adjustable printing parameters 7 are individually identified for each printing nozzle group 10a, 10b, 10c, 10d, 10e. For example, printing parameter values ​​1 selected from the group of one or more printing parameters 7: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic may be identified for each printing nozzle group 10a, 10b, 10c, 10d, 10e.

[0179] The print parameter values ​​1 identified for each print nozzle group 10a, 10b, 10c, 10d, 10e can then be used to print a pattern on the surface 3 of the spectacle lens substrate 4. Optionally, the surface 3 of the spectacle lens substrate 4 may be Against The tilt angle of the print head 5 is not adjusted before and / or during printing.

[0180] Fig. 12 shows a flow chart of another embodiment of a computer-implemented method 100 for identifying printing parameter values ​​1 of an inkjet printing device 2 for printing a pattern on a surface 3 of an eyeglass lens substrate 4. With regard to steps S1 and S2, please refer to the description of Fig. 10.

[0181] Step S3, ie, identifying printing parameter values ​​1 of adjustable printing parameters 7, 7a, 7b, 7c, 7d, 7e, 7f for each printing nozzle group 10a, 10b, 10c, 10d, 10e individually, includes sub-steps S4 to S6.

[0182] In step S4, a look-up table 13 and a cost function are provided. For example, the look-up table 13 can be read from a storage medium. The look-up table 13 contains correlations between the parameters 11, 11a, 11b, 11c describing the geometrical relationship between the surface 3 of the spectacle lens substrate 4 and the print head 5 and the adjustable printing parameters 7, 7a, 7b, 7c, 7d, 7e, 7f. The cost function can be either a universal evaluation cost function or a cost function dedicated to a particular use case, i.e. taking into account quality parameters relevant to the particular use case.

[0183] In step S5, the cost function is applied to the look-up table 13 and optimized to search for suitable printing parameter values ​​1 corresponding to the input data 8, 8a, 8b, 8c, 8d. In other words, the printing parameter values ​​1 leading to the minimum total cost, e.g. the minimum possible number of satellites as quality parameters, taking into account the entire surface 3 of the spectacle lens substrate 4 to be printed thereon, are searched for in the look-up table 13. The optimization of the cost function can be performed using at least one method selected from the group consisting of steepest descent method, genetic algorithms and machine learning.

[0184] In step S6, a parameter map 12 is inferred taking into account the optimization results, which comprises the assignment of printing parameter values ​​1 to specific points on the surface 3 of the spectacle lens substrate 4. In other words, the printing parameter values ​​1 are determined individually for each printing nozzle group 10a, 10b, 10c, 10d, 10e and stored as parameter map 12.

[0185] Then, a pattern can be printed on the surface 3 of the spectacle lens substrate 4 using the printing parameter values ​​1, i.e. parameter map 12, determined for each printing nozzle group 10a, 10b, 10c, 10d, 10e. If the printing parameter values ​​1 cannot be modified during a single printing process, e.g. the grey levels cannot be changed, the actual printing parameter values ​​1 and their distribution can be discretized, e.g. from 0 to four parts of radius R, and instead of one image several sub-images are printed, e.g. four sub-images with different printing parameter values, e.g. four "rings" that fit together.

[0186] The block diagram shown in FIG. 13 illustrates yet another embodiment of a computer-implemented method 100 for identifying printing parameter values ​​1 of an inkjet printing device 2 for printing a pattern on a surface 3 of an eyeglass lens substrate 4.

[0187] The method 100 is based on the discovery that each surface point of the surface 3 of the spectacle lens substrate 4 to be printed should be considered individually by calculating and applying optimized printing parameters 7a, 7b, 7c, 7d, 7e, 7f. The necessary input data 8a, 8b, 8c, 8d obtained in step S1 relate to the geometrical characteristics of the surface 3 of the spectacle lens substrate 4, i.e. the lens shape, as well as the geometrical characteristics of the print head 5 as part of the inkjet printing device 2, and optionally the environmental conditions and the material properties of the ink 9 and / or the spectacle lens substrate 4.

[0188] From this input data 8a, 8b, 8c, 8d, parameter values ​​are inferred for parameters 11a, 11b, 11c that describe the geometric relationship between the surface 3 of the spectacle lens substrate 4 and the print head 5. These describe the "inkjet printing device-spectacle lens substrate" system during the printing process. Preferred parameters 11a, 11b, 11c include, for example, the incidence angle α, the displacement vector, the velocity vector, the distance Δ, and the arc length s.

[0189] In step S3, a printing parameter value 1 of the printing parameters 7a, 7b, 7c, 7d, 7e, 7f is calculated for each printing nozzle group 10a, 10b, 10c, 10d, 10e previously created in step S2. The printing parameters 7a, 7b, 7c, 7d, 7e, 7f considered in this embodiment are the firing temperature, the firing duration, the firing frequency, the norm value, the waveform parameter, and the adjustable ink characteristics. Other settings and / or characteristics may also be considered.

[0190] To retrieve the printing parameter values ​​1, a look-up table 13 is provided in step S4, which is created in advance and contains the correlation of the printing parameter values ​​1 of the adjustable printing parameters 7a, 7b, 7c, 7d, 7e, 7f with the parameters 11a, 11b, 11c describing the geometrical relationship between the surface 3 of the spectacle lens substrate 4 and the print head. The printing parameters 7a, 7b, 7c, 7d, 7e, 7f can be understood as function parameters. For each parameter 11a, 11b, 11c describing the geometrical relationship between the surface 3 of the spectacle lens substrate 4 and the print head 5 or a combination thereof, a specific set of printing parameters 7a, 7b, 7c, 7d, 7e, 7f is assigned. Input data 8c, 8d on environmental conditions and material properties can be taken into account when creating the look-up table 13.

[0191] Further, in step S5 a cost function is provided, which is applied to the look-up table 13 and optimized. Finally, in step S6 a parameter map 12 is retrieved from the optimized cost function. The printing parameters 7a, 7b, 7c, 7d, 7e, 7f assigned to a particular point cloud on the surface 3 of the spectacle lens substrate 4 are stored in the parameter map 12.

[0192] FIG. 14 illustrates an embodiment of an inkjet printing apparatus 2 using drop-on-demand technology. The inkjet printing apparatus 2 includes a print head 5 with a plurality of print nozzles 6. The inkjet printing apparatus 2 further includes a data processing system 200 including a processor 20 and a storage medium 21 coupled to the processor 20, which is represented by a double-headed arrow in FIG. 14. The processor 20 is adapted to group the plurality of print nozzles 6 into at least two print nozzle groups 10a, 10b, 10c, 10d, 10e and to individually determine print parameter values ​​1 of at least one adjustable print parameter 7, 7a, 7b, 7c, 7d, 7e, 7f of each print nozzle group 10a, 10b, 10c, 10d, 10e based on a computer program stored in the storage medium 21. The storage medium 21 may also be used to store the look-up table 13 and / or the retrieved parameter map 12. In other words, the data processing system 200 may execute one of the computer-implemented methods described herein for determining the printing parameter values ​​1. The determined printing parameter values ​​1 are transmitted to the print head 5 and the print nozzles 6 to perform the printing process.

[0193] The creation of the lookup table 13 and the retrieval of the parameter map 12 will now be described in more detail with reference to FIGS.

[0194] In this embodiment, hot melt printing technology is used to print wax droplets in different patterns on a convexly curved surface 3 of an eyeglass lens substrate 4. The surface 3 and the applied wax pattern are photographed using an industrial microscope. The images obtained for a particular tile of the printed wax pattern are analyzed in terms of the circularity of the applied droplets and the number of satellites (small, spread out, undesired droplets) formed. These characteristics can be quantified and are used as examples of print quality parameters.

[0195] Using a Zeiss Recon system, overview images of the entire surface 3 of the spectacle lens substrate 4 are obtained and the relative tile positions of the applied wax pattern are reconstructed from these images. Combining the data collected from the microscope and the Recon system, calculated quality parameter values ​​are related to the positions of the elementary tiles on the surface 3. This information is used to derive a look-up table 13 of appropriate values ​​for the printing parameters 7, 7a, 7b, 7c, 7d, 7e, 7f to be printed on the surface 3 of the spectacle lens substrate 4.

[0196] The experimental steps include hot melt printing on the surface 3 of the spectacle lens substrate 4 using different norm value settings of the inkjet printing device 2 (without moving during pre-discharge), taking Recon images of the printed surface 3, analysing the Recon images to localise the tiles, taking microscopic images of the tiles with different applied patterns, defining quality parameters and analysing the microscopic images, mapping the quality parameters to the surface 3 and running the optimiser to create a parameter map 12 for each lens.

[0197] Printing on the surface of eyeglass lens material Printing is done using a Teco printer with a Xerox M1 printhead. From the technical datasheet of the Xerox M1 printhead series the absolute and relative positions of the individual print nozzles 6, 6a, 6b, 6c are known. Based on this information the (x,y) array of the individual nozzles is derived and used to identify a tile during image analysis. In a standard printing process it is known which print nozzles 6, 6a, 6b, 6c pass over which part of the surface 3 and the nozzle firing sequence is calculated accordingly.

[0198] First, the spectacle lens substrate 4 to be printed is positioned under the print head 5 using a positioning system. Using the "prefire" function of the print head 5, wax is deposited on the surface 3 of the spectacle lens substrate 4. During the "prefire", the spectacle lens substrate 4 does not move. The pattern formed on the surface 3 corresponds to the grid defined by the nozzle plate of the Xerox M1 print head. During the experiment, five shots (waveform repetition - 10 Hz, 500 ms) are fired for each of a number of six spectacle lens substrates 4 with the same geometry and minimum distance to the print head 5. Between these spectacle lens substrates 4, the norm values ​​of the printing parameters 7, 7a, 7b, 7c, 7d, 7e, 7f are increased from 20 to 60 in increments of 10.

[0199] 3. Recon Image Acquisition and Analysis The relative and absolute positions of the grid tiles on the surface 3 of the spectacle lens substrate 4 can be reconstructed from the Recon images. The Zeiss Recon system is a system used to acquire high quality images of spectacle lenses, e.g. for the detection of laser engraving and similar structures. In this case, the Recon system is used to detect the (x,y) position of one wax droplet. For software, OpenCV and Python were used to analyze the Recon images.

[0200] In Figure 15 the outer contour of the spectacle lens substrate 4 and its centre (in pixel coordinates of the image) are shown. The centre was determined by minimising the sum of the squared distances to the points that form the lens contour. Once the position of the lens centre is known, the average distance from it to all the contour points of the spectacle lens substrate 4 is calculated. From these numbers and the known physical diameter of the spectacle lens substrate 4 (65mm), the appropriate multiplication factor (in pixels-micrometres) can be calculated.

[0201] In the next step, the deposited wax droplets are recognized by OpenCV and their positions overlap with the markers (black dots in Fig. 15). A convex hull is constructed around these markers and three of its points (marked as large black dots) are used to obtain unit vectors. These vectors are needed to construct a rotation matrix to align the coordinate systems of the image and the read nozzle positions of the print head 5. The position of the center of the surface 3 from the Recon image is also used for the (x,y) translation of the read nozzle array.

[0202] In Figure 16, the printed wax dots are overlaid with the "theoretical" positions of the printing nozzles 6, 6a, 6b, 6c (black dots), which match well with the observed dots. The centre points of the tiles used for microscopic analysis (the coordinates of the "real" droplets) are shown as crosses.

[0203] Microscopic image acquisition and analysis Microscopic images were acquired using a Zeiss Smart Zoom 5 microscope, which was tilted according to the tile position on the surface 3 of the spectacle lens substrate 4 to minimize defocus areas and maximize contrast. The settings used for microscopic image acquisition were: microscope type - image, objective - 5, magnification - 101×, resolution - 2.2040 μm px. -1 , exposure time 0.2819ms, illumination – top right illumination.

[0204] For the Recon images, OpenCV and Python were used to analyze the microscopy images. Tile number 5 of Surface 3, printed with norm value 50, is shown in Figure 17. The center point of this tile is marked in the Recon image in Figure 16. Going up from the center of the image on the left, this is the fifth of eight black crosses.

[0205] The first step of image analysis is the conversion of the raw image to grayscale. Secondly, a Gaussian blur is applied to the image to eliminate pixel noise that affects contour recognition (Figure 18). The necessary "pre-processing" of the image depends on the analysis technique used and the experimental setup used. For example, recognition of large dots ("main features") was best performed using a Gaussian blur with kernel size 15. For detection of smaller sized satellites, a Gaussian blur with kernel size 5 was used.

[0206] From the grayscale image with Gaussian blur applied, a black and white image can be obtained using an adaptive thresholding function. The parameters used here are (111-6) for main feature detection and (141-6) for satellite detection, respectively. The thresholded black and white image for main feature detection is shown in Figure 19. Contour recognition is performed on the black and white image to detect the main features (A<300px 2 ) or satellite (20px 2 <A<300px 2 ) The first derived quality parameter is the number of satellites per tile (more is worse). The second quality parameter is the circularity of the detected key features (circularity equals 1, see equation (I)). C=4 * π * A / P 2 Formula (I) where C is the circularity, A=blob area in pixels squared, and P=blob in pixels.

[0207] In FIG. 19, the main features found are marked with dashed rectangles and the satellites found are marked with black dots.

[0208] Parameter mapping and optimization For each analyzed microscope image, the obtained quality parameters (mean feature circularity and number of satellites) are attributed to the center point of the corresponding tile obtained from the Recon image. For convenience, the calculated (x,y) points are expressed as the equivalent radius of a 65 mm diameter spectacle lens substrate 4 (see y-axis in Figures 20-22). For the systematic construction of a database or look-up table 13, the surface-nozzle distance is preferably used as a non-lens specific property.

[0209] The black crosses in Figures 20 and 21 represent one exemplary test setup. A finer mesh is used for linear interpolation between these support points. Visually, the norm value of 40 seems to be a good choice for the applied conditions. For the number of satellites formed, the norm value of 40 also seems to perform well. Finally, the aim is to define a cost function based on the right quality parameters in order to optimize the printing process therefrom.

[0210] As an example, the function shown in equation (II) is used to create FIG. 22, i.e. to calculate the cost depending on different equivalent radii and norm values, while the number of satellites formed and the circularity are taken into account as quality parameters. Cost=gridz1 / (gridz0) 3 Formula (II)

[0211] The variable gridz1 is the number of satellites per tile and the variable gridz0 is the average circularity of the detected droplets. Since one has to go from 0 to 1 (the equivalent radius of the spectacle lens substrate 4) through this cost function, the "cheapest" route is found using the selected optimizer and can include other attendant conditions if necessary. For example, the cost function can focus on satellites or on circularity depending on the concrete application. The "cheapest route" in this particular example is marked with a black arrow and corresponds to a norm value of 20. By defining different cost functions, different cheapest routes can be obtained and these do not necessarily have to be linear.

[0212] The black arrow in Fig. 22 is a graphical representation of a parameter map 12, which includes a specified printing parameter value 1, i.e., norm value 20. In other cases, the specified optimal norm value may vary with equivalent radius, and different norm values ​​are specified for different printing nozzle groups 10a, 10b, 10c, 10d, 10e.

[0213] FIG. 23 shows a graphical representation similar to FIG. 22, but using a differently defined cost function (Equation (III)). Cost=Cost=gridz1 / (gridz0) 2 Formula (III)

[0214] In formula (III), the number of satellites is less clear compared to formula (II), i.e. (grindz1) 3 instead of (gridz1) 2 Therefore, the impact of both quality parameters is more balanced.

[0215] Preferred features of the present invention are: 1. A computer-implemented method for identifying printing parameter values ​​for an inkjet printing device for printing a pattern on a surface of an eyeglass lens substrate, the inkjet printing device including a print head having a plurality of printing nozzles; - grouping the plurality of print nozzles into at least two print nozzle groups; - individually determining a printing parameter value for at least one adjustable printing parameter for each group of printing nozzles; Includes. 2. The method of claim 1, wherein the at least one adjustment parameter is selected from the group consisting of a jetting temperature, a jetting duration, a jetting frequency, a norm value, a waveform parameter, and an adjustable ink characteristic. 3. The method of paragraph 1 or 2, wherein each print nozzle group includes a single print nozzle. 4. - obtaining input data relating to the surface of the spectacle lens substrate and to geometrical characteristics of the print head; Including, The printing parameter values ​​are individually determined according to the input data; Any one of methods 1 to 3. 5. The method of clause 4, wherein the input data is used to identify a geometric relationship between a surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an incidence angle α, a distance Δ, and an arc length s. 6. The method of claim 4 or 5, wherein the input data includes data regarding environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate. 7. The method of any one of claims 1 to 6, wherein the method step of individually identifying printing parameter values ​​for at least one adjustable printing parameter includes a step of inferring a parameter map including an assignment of printing parameter values ​​to specific points on a surface of the eyeglass lens substrate. 8. The method of clause 7 combined with at least clause 5, wherein the parameter map is inferred by optimizing a cost function applied to the correlation between parameters describing the geometric relationship between the surface of the eyeglass lens substrate and the print head and adjustable printing parameters. 9. The method of claim 8, wherein the optimization uses at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. 10. The method of paragraph 8 or 9, in which the cost function defines the cost according to the quality parameters. 11. The method of claim 10, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 12. The parameter map is estimated using a lookup table, method 7-11. 13. The method according to any one of claims 1 to 12, wherein the surface of the spectacle lens substrate is a curved surface. 14. The method of any one of claims 1 to 13, wherein at least two print nozzle groups are used within a single print pass. 15. A printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually determined, thereby applying a print parameter value to the surface of the eyeglass lens substrate. Against15. The method of any one of paragraphs 1 to 14, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 16. The method of any one of claims 1 to 15, wherein a printing parameter value for at least one adjustable printing parameter of each printing nozzle group is individually identified, whereby the pose of both the eyeglass lens substrate and the print head remains constant relative to each other during printing of the pattern on the surface of the eyeglass lens substrate. 17. A data processing system including a processor and a storage medium coupled to the processor, the processor being adapted to determine, based on a computer program stored on the storage medium, print parameter values ​​for an inkjet printing device for printing a pattern on a curved surface of an eyeglass lens substrate, the inkjet printing device including a print head having a plurality of print nozzles, the processor being adapted to group the plurality of print nozzles into at least two print nozzle groups and to determine print parameter values ​​for at least one adjustable print parameter for each print nozzle group individually. 18. The data processing system of claim 17, wherein the at least one adjustable printing parameter is selected from the group of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic. 19. The data processing system of claim 17 or 18, wherein each printing nozzle group includes a single printing nozzle. 20. A data processing system according to any one of claims 17 to 19, wherein the processor is adapted to obtain input data relating to the surface of the eyeglass lens substrate and geometric characteristics of the print head, and the processor is adapted to individually identify printing parameter values ​​in response to the input data. 21. The data processing system of claim 20, wherein the processor is adapted to use the input data to identify a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an angle of incidence α, a distance Δ, and an arc length s. 22. The data processing system of claim 20 or 21, wherein the input data includes data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate. 23. The data processing system of any one of claims 17 to 22, wherein the processor is adapted to infer a parameter map comprising an assignment of printing parameter values ​​to a set of specific points on a surface of the eyeglass lens substrate. 24. The data processing system of claim 23 in combination with at least claim 21, wherein the processor is adapted to estimate the parameter map by optimizing a cost function applied to a correlation between parameters describing a geometric relationship between the surface of the eyeglass lens substrate and the print head and adjustable printing parameters. 25. The data processing system of claim 24, wherein the optimization uses at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. 26. A data processing system according to claim 24 or 25, wherein the cost function defines costs according to the quality parameters. 27. The data processing system of claim 26, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 28. A data processing system according to any one of paragraphs 23 to 27, wherein the parameter map is estimated using a look-up table. 29. The data processing system according to any one of claims 17 to 28, wherein the surface of the eyeglass lens substrate is a curved surface. 30. The data processing system of any one of claims 17 to 29, wherein at least two print nozzle groups are used within a single printing pass. 31. A printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually determined, thereby applying a print parameter value to the surface of the eyeglass lens substrate. Against 31. The data processing system according to any one of claims 17 to 30, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 32. A data processing system according to any one of claims 17 to 31, wherein a printing parameter value for at least one adjustable printing parameter of each printing nozzle group is individually identified, whereby the pose of both the eyeglass lens substrate and the printing head remains constant relative to each other during printing of a pattern on the surface of the eyeglass lens substrate. 33. A computer program comprising instructions that, when executed by a computer, cause the computer to determine printing parameter values ​​for an inkjet printing device for printing a pattern on a curved surface of an eyeglass lens substrate, the inkjet printing device including a print head having a plurality of printing nozzles, the instructions causing the computer to group the plurality of printing nozzles into at least two printing nozzle groups and to separately determine printing parameter values ​​for at least one adjustable printing parameter for each printing nozzle group. 34. The computer program of claim 33, wherein the at least one adjustable printing parameter is selected from the group of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic. 35. The computer program of claim 33 or 34, wherein each print nozzle group includes a single print nozzle. 36. A computer program according to any one of claims 33 to 35, wherein the instructions cause the computer to obtain input data relating to the surface of the eyeglass lens substrate and geometric characteristics of the print head, and the computer is caused to individually determine printing parameter values ​​in response to the input data. 37. The computer program of clause 36, wherein the instructions cause the computer to use the input data to determine a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an angle of incidence α, a distance Δ, and an arc length s. 38. The computer program of claim 36 or 37, wherein the input data includes data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the spectacle lens substrate. 39. The computer program of any one of claims 33 to 38, wherein the instructions cause the computer to infer a parameter map including an assignment of printing parameter values ​​to specific points on a surface of an eyeglass lens substrate. 40. A computer program according to claim 39 in combination with at least claim 37, the instructions causing the computer to infer the parameter map by optimizing a cost function applied to a correlation of parameters describing a geometric relationship between the surface of the eyeglass lens substrate and the print head with adjustable printing parameters. 41. The computer program of item 40, wherein the optimization uses at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. 42. The computer program of paragraph 40 or 41, wherein the cost function defines costs according to the quality parameters. 43. The computer program of claim 42, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 44. The computer program of any one of paragraphs 39 to 43, wherein the parameter map is estimated using a look-up table. 45. The computer program of any one of claims 33 to 44, wherein the surface of the eyeglass lens substrate is a curved surface. 46. ​​A data processing system according to any one of claims 33 to 44, wherein at least two printing nozzle groups are to be used within a single printing pass. 47. A printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually determined, thereby applying a print parameter value to the surface of the eyeglass lens substrate. Against 47. The computer program of any one of claims 33 to 46, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 48. The computer program of any one of clauses 33 to 47, wherein a printing parameter value for at least one adjustable printing parameter of each printing nozzle group is individually identified, whereby the pose of both the eyeglass lens substrate and the printing head remains constant relative to each other during printing of a pattern on the surface of the eyeglass lens substrate. 49. A non-transitory computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to determine printing parameter values ​​for an inkjet printing device for printing a pattern on a curved surface of an eyeglass lens substrate, the inkjet printing device including a print head having a plurality of printing nozzles, the instructions causing the computer to group the plurality of printing nozzles into at least two printing nozzle groups and to separately determine printing parameter values ​​for at least one adjustable printing parameter for each printing nozzle group. 50. The non-transitory computer-readable storage medium of claim 49, wherein the at least one adjustable printing parameter is selected from the group of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic. 51. The non-transitory computer-readable storage medium of claim 49 or 50, wherein each print nozzle group includes a single print nozzle. 52. The non-transitory computer-readable storage medium of any one of claims 49 to 51, wherein the instructions cause the computer to obtain input data relating to the surface of the eyeglass lens substrate and geometric characteristics of the print head, and the computer is caused to individually determine printing parameter values ​​in response to the input data. 53. The non-transitory computer-readable storage medium of paragraph 52, wherein the instructions cause the computer to use the input data to determine a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an angle of incidence α, a distance Δ, and an arc length s. 54. The non-transitory computer-readable storage medium of claim 52 or 53, wherein the input data includes data regarding environmental conditions, non-adjustable ink characteristics, and / or material characteristics of the eyeglass lens substrate. 55. The non-transitory computer-readable storage medium of any one of claims 49 to 54, wherein the instructions cause the computer to infer a parameter map including an assignment of printing parameter values ​​to specific points on a surface of an eyeglass lens substrate. 56. The non-transitory computer-readable storage medium of clause 55 in combination with at least clause 53, wherein the instructions cause the computer to infer the parameter map by optimizing a cost function applied to a correlation of parameters describing a geometric relationship between the surface of the eyeglass lens substrate and the print head with adjustable printing parameters. 57. The non-transitory computer-readable storage medium of item 56, wherein the optimization uses at least one method selected from the group consisting of steepest descent, genetic algorithms, and machine learning. 58. The non-transitory computer-readable storage medium of claim 56 or 57, wherein the cost function defines a cost according to the quality parameter. 59. The non-transitory computer-readable storage medium of claim 58, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 60. The non-transitory computer-readable storage medium of any one of claims 55 to 59, wherein the parameter map is estimated using a lookup table. 61. The non-transitory computer-readable storage medium of any one of claims 49 to 60, wherein the surface of the eyeglass lens substrate is a curved surface. 62. The non-transitory computer-readable storage medium of any one of claims 49 to 61, wherein at least two print nozzle groups are to be used within a single printing pass. 63. A printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually determined, thereby applying a print parameter value to the surface of the eyeglass lens substrate. Against 63. The non-transitory computer-readable storage medium of any one of claims 49 to 62, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 64. The non-transitory computer-readable storage medium of any one of claims 49 to 63, wherein a printing parameter value for at least one adjustable printing parameter of each printing nozzle group is individually identified, whereby a pose of both the eyeglass lens substrate and the print head remains constant relative to each other during printing of a pattern on the surface of the eyeglass lens substrate. 65. An inkjet printing method, wherein a pattern is printed on a curved surface of an eyeglass lens substrate with an inkjet printing device including a print head with a plurality of printing nozzles using a printing parameter value of at least one adjustable printing parameter, and the printing parameter value of the at least one adjustable printing parameter is determined according to the computer-implemented method of any one of clauses 1 to 16. 66. The method of claim 65, wherein the pattern is printed for at least one process selected from the group consisting of permanent lens marking, temporary lens marking, application of a masking layer, application of an adhesive layer spot, additive manufacturing, and coloring. 67. On the surface of eyeglass lens substrate Against 67. The method of claim 65 or 66, wherein the tilt angle of the print head is not adjusted before and / or during printing. 68. The method of any one of paragraphs 65 to 67, wherein the pose of both the eyeglass lens substrate and the print head remain constant relative to each other during printing of the pattern onto the surface of the eyeglass lens substrate. 69. An inkjet printing apparatus for printing a pattern on a curved surface of an eyeglass lens substrate, comprising: a print head comprising a plurality of print nozzles; - a data processing system including a processor and a storage medium coupled to the processor, the processor adapted to determine printing parameter values ​​based on a computer program stored on the storage medium; Including, An inkjet printing apparatus, wherein the processor is adapted to group the plurality of print nozzles into at least two print nozzle groups and to separately identify a print parameter value for at least one adjustable print parameter for each print nozzle group. 70. The inkjet printing apparatus of claim 69, wherein the at least one adjustable printing parameter is selected from the group of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic. 71. The inkjet printing apparatus of claim 69 or 70, wherein each print nozzle group includes a single print nozzle. 72. An inkjet printing device of any one of claims 69 to 71, wherein the processor is configured to obtain input data relating to the surface of the eyeglass lens substrate and geometric characteristics of the print head, and the processor is configured to individually identify printing parameter values ​​in response to the input data. 73. The inkjet printing apparatus of clause 72, wherein the processor is adapted to use the input data to determine a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an incidence angle α, a distance Δ, and an arc length s. 74. An inkjet printing apparatus according to claim 72 or 73, wherein the input data includes data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate. 75. The inkjet printing device of any one of claims 69 to 74, wherein the processor is adapted to infer a parameter map including an assignment of printing parameter values ​​to a set of particular points on a surface of the eyeglass lens substrate. 76. An inkjet printing apparatus according to claim 75 in combination with at least claim 59, wherein the processor is adapted to estimate the parameter map by optimizing a cost function applied to a correlation of parameters describing a geometric relationship between the surface of the eyeglass lens substrate and the print head with adjustable printing parameters. 77. The inkjet printing device of item 76, wherein the optimization uses at least one method selected from the group consisting of steepest descent method, genetic algorithm, and machine learning. 78. An inkjet printing apparatus according to claim 76 or 77, wherein the cost function defines costs according to the quality parameters. 79. An inkjet printing apparatus according to claim 78, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 80. An inkjet printing device according to any one of claims 75 to 79, wherein the parameter map is estimated using a lookup table. 81. The inkjet printing apparatus of any one of items 69 to 80, wherein the surface of the eyeglass lens substrate is a curved surface. 82. An inkjet printing apparatus according to any one of claims 69 to 81, wherein at least two groups of printing nozzles are used within a single printing pass. 83. A printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually determined, thereby applying a print parameter value to the surface of the eyeglass lens substrate. Against 83. The inkjet printing apparatus of any one of items 69 to 82, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 84. An inkjet printing device of any one of claims 69 to 83, wherein a printing parameter value for at least one adjustable printing parameter of each printing nozzle group is individually identified, whereby the pose of both the eyeglass lens substrate and the printing head remains constant relative to each other during printing of a pattern on the surface of the eyeglass lens substrate. 85. A spectacle lens substrate, the pattern printed on the curved surface of which is obtainable by any one of the methods of items 65 to 68. 86. A data set in the form of a computer-readable data carrier signal, the data set including at least one of the following types of data: (i) printing parameter values ​​of at least one adjustable printing parameter individual for at least two printing nozzle groups of an inkjet printing device including a print head with a plurality of printing nozzles, configured to be supplied to the inkjet printing device to print a pattern on a surface of an eyeglass lens substrate, or (ii) data including computer-readable instructions for controlling an inkjet printing device to print a pattern on a surface of an eyeglass lens substrate by applying individual printing parameter values ​​of the at least one adjustable printing parameter to at least two printing nozzle groups of an inkjet printing device including a print head with a plurality of printing nozzles. 87. The data set of item 86, wherein the at least one adjustable printing parameter is selected from the group of: jetting temperature, jetting duration, jetting frequency, norm value, waveform parameter, and adjustable ink characteristic. 88. Data of paragraph 86 or 87, where each printing nozzle group includes a single printing nozzle. 89. The data set of any one of paragraphs 86 to 88, wherein the instructions cause the computer to obtain input data relating to the surface of the eyeglass lens substrate and geometric characteristics of the print head, and the computer is caused to individually determine printing parameter values ​​in response to the input data. 90. The data set of clause 89, wherein the instructions cause the computer to use the input data to identify a geometric relationship between the surface of the eyeglass lens substrate and the print head, the geometric relationship being described by at least one parameter selected from the group consisting of a displacement vector, a velocity vector, an angle of incidence α, a distance Δ, and an arc length s. 91. The data set of paragraphs 89 or 90, wherein the input data includes data relating to environmental conditions, non-adjustable ink properties, and / or material properties of the eyeglass lens substrate. 92. The data set of any one of paragraphs 86 to 91, wherein the instructions cause the computer to infer a parameter map including an assignment of printing parameter values ​​to specific points on a surface of the eyeglass lens substrate. 93. The instructions cause the computer to infer a parameter map by optimizing a cost function applied to a correlation of parameters describing a geometric relationship between a surface of an eyeglass lens substrate and a print head with adjustable printing parameters, the data set of 92 terms being combined with at least 84 terms. 94. The dataset of item 93, wherein the optimization uses at least one method selected from the group consisting of steepest descent, genetic algorithm, and machine learning. 95. A data set according to paragraph 93 or 94, in which the cost function defines the cost according to the quality parameters. 96. The data set of clause 95, wherein the quality parameters include the number of satellites formed and / or the circularity of the average printed feature. 97. The parameter map is estimated using a lookup table, for any one of the data sets 92-96. 98. The non-transitory computer-readable storage medium of any one of claims 86 to 97, wherein the surface of the eyeglass lens substrate is a curved surface. 99. The non-transitory computer-readable storage medium of any one of claims 86 to 98, wherein at least two print nozzle groups are to be used within a single printing pass. 100. A print parameter value for at least one adjustable print parameter for each print nozzle group is individually determined, thereby applying a print parameter value to a surface of the eyeglass lens substrate. Against 86-99. The non-transitory computer-readable storage medium of any one of claims 86 to 99, wherein the tilt angle of the print head does not need to be adjusted before and / or during printing. 101. The non-transitory computer-readable storage medium of any one of claims 86 to 100, wherein a printing parameter value for at least one adjustable printing parameter for each printing nozzle group is individually identified, whereby a pose of both the eyeglass lens substrate and the print head remains constant with respect to each other during printing of a pattern on the surface of the eyeglass lens substrate. 102. A data set in the form of a computer-readable data signal comprising at least one of the following types of data: (i) a virtual representation of an apparatus according to any one of paragraphs 69 to 84 configured to be supplied to one or more manufacturing machines for producing the apparatus; or (ii) data comprising computer-readable instructions for controlling one or more manufacturing machines for producing an apparatus according to any one of paragraphs 69 to 84. [Explanation of symbols]

[0216] 1 Printing parameter values 2. Inkjet printing device 3 surface 4. Eyeglass lens substrate 5 Print Head 6, 6a, 6b, 6c Printing nozzles 7, 7a, 7b, 7c, 7d, 7e, 7f printing parameters 8, 8a, 8b, 8c, 8d Input data 9. Ink 10a, 10b, 10c, 10d, 10e Printing nozzle groups 11, 11a, 11b, 11c Parameters describing geometric relationships 12 Parameter Map 13. Lookup Tables 20 processors 21 Storage medium 100 ways 200 Data Processing System D diameter dx, dy, dz discretized difference in the coordinate system used j Discharge vector m Print head movement direction n normal vector r True Front Curve s Arc length α angle of incidence Δ 1 , Δ 2 The distance between the printing nozzle and the substrate surface S1. Obtain input data regarding the surface of the eyeglass lens substrate and the geometric characteristics of the print head of the inkjet printing device. S2 Group multiple print nozzles into at least two print nozzle groups S3. Independently identifying print parameter values ​​of adjustable print parameters for each print nozzle group. S4 Provide lookup tables and cost functions. S5 Apply the required function and optimize S6 Infer Parameter Map

Claims

1. A computer-implemented method (100) for determining printing parameter values ​​(1) of an inkjet printing device (2) for printing a pattern on a surface (3) of an eyeglass lens substrate (4) including a curved surface, said inkjet printing device (2) including a print head (5) as one single component with a plurality of printing nozzles (6, 6a, 6b, 6c), comprising the following method steps executed on a computer: - grouping (S2) said plurality of print nozzles (6, 6a, 6b, 6c) into at least two print nozzle groups (10a, 10b, 10c, 10d, 10e); - a step (S3) of individually determining a printing parameter value (1) of at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) of each printing nozzle group (10a, 10b, 10c, 10d, 10e); Including, A computer-implemented method (100), characterized in that the print head (5) is configured not to be tilted with respect to the eyeglass lens substrate (4).

2. 2. The computer-implemented method (100) of claim 1, wherein the at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) is selected from the group consisting of a jetting temperature, a jetting duration, a jetting frequency, a norm value, a waveform parameter, and an adjustable ink characteristic.

3. 3. The computer-implemented method (100) of claim 1 or claim 2, wherein at least two groups of print nozzles are to be used within a single printing pass.

4. 3. A computer-implemented method (100) according to claim 1 or claim 2, characterized in that each print nozzle group (10a, 10b, 10c, 10d, 10e) comprises a single print nozzle (6, 6a, 6b, 6c).

5. - obtaining input data (8, 8a, 8b) relating to the geometrical characteristics of said surface (3) of said spectacle lens substrate (4) and to the geometrical characteristics of said print head (5), 3. A computer-implemented method (100) according to claim 1 or 2, characterized in that the printing parameter values ​​(1) are individually determined depending on the input data (8, 8a, 8b).

6. 6. The computer-implemented method (100) of claim 5, characterized in that the input data is used to determine a geometric relationship between the surface (3) of the spectacle lens substrate (4) and the print head (5), and the printing parameter values ​​(1) are determined individually depending on the geometric relationship.

7. 7. The computer-implemented method (100) of claim 6, wherein the term geometric relationship refers to an alignment of the print head and the eyeglass lens substrate with respect to each other.

8. 7. The computer-implemented method (100) of claim 6, characterized in that the geometric relationship is described by at least one parameter (11a, 11b, 11c) selected from the group consisting of a displacement vector, a velocity vector, an angle of incidence α, a distance Δ, and an arc length s.

9. 6. A computer-implemented method (100) according to claim 5, characterized in that the input data (8, 8a, 8b) comprise data relating to environmental conditions, non-adjustable ink properties and / or material properties of the spectacle lens substrate (4).

10. 7. The computer-implemented method (100) of claim 6, characterized in that the method step (S3) of individually identifying the printing parameter values ​​(1) of the at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) comprises a step (S6) of estimating a parameter map (12) comprising an assignment of printing parameter values ​​(1) to specific data points on the surface (3) of the eyeglass lens substrate (4).

11. 11. The computer-implemented method (100) of claim 10, characterized in that estimating the parameter map (12) comprises transforming the surface (3) of the spectacle lens substrate (4) into a grid of data points.

12. 12. The computer-implemented method (100) of claim 11, characterized in that the method step (S3) of individually identifying the printing parameter values ​​(1) of the at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) comprises providing a look-up table containing correlations between parameters (11a, 11b, 11c) describing the geometrical relationship between the surface (3) of the spectacle lens substrate (4) and the print head and printing parameter values ​​(1) of the adjustable printing parameters (7, 7a, 7b, 7c, 7d, 7e, 7f).

13. 13. The computer-implemented method (100) of claim 12, wherein identifying the printing parameter values ​​(1) comprises deriving a set of printing parameter values ​​from the lookup table of the data points.

14. 11. The computer-implemented method (100) of claim 10, characterized in that the parameter map (12) is inferred by optimizing (S5) a cost function applied to the correlation of parameters (11a, 11b, 11c) describing the geometrical relationship between the surface (3) of the spectacle lens substrate (4) and the print head (5) with the printing parameter values ​​(1) of the adjustable printing parameters (7, 7a, 7b, 7c, 7d, 7e, 7f).

15. 3. A computer-implemented method (100) according to claim 1 or 2, characterized in that the printing parameter values ​​(1) of the at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) of each printing nozzle group (10a, 10b, 10c, 10d, 10e) are specified individually, whereby the tilt angle of the printing head (5) with respect to the surface (3) of the spectacle lens substrate (4) does not have to be adjusted before and / or during printing.

16. A data processing system (200) including a processor (20) and a storage medium (21) coupled to the processor (20), the processor (20) being adapted to determine, based on a computer program stored on the storage medium (21), print parameter values ​​(1) of an inkjet printing device (2) for printing a pattern on a surface (3) of an eyeglass lens substrate (4) including a curved surface, the inkjet printing device (2) including a print head (5) as one separate component with a plurality of print nozzles (6, 6a, 6b, 6c). 200), wherein the processor (20) is adapted to group the plurality of print nozzles (6, 6a, 6b, 6c) into at least two print nozzle groups (10a, 10b, 10c, 10d, 10e) and to individually determine a print parameter value (1) for at least one adjustable print parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) for each print nozzle group (10a, 10b, 10c, 10d, 10e), and wherein the print head (5) is configured not to be tilted with respect to the eyeglass lens substrate (4).

17. 17. The data processing system (200) of claim 16, characterized in that the processor (20) is adapted to individually determine the printing parameter values ​​(1) depending on the geometric characteristics of the spectacle lens substrate (4) and the geometric characteristics of the print head (5).

18. 1. A computer program comprising instructions, when executed by a computer, that cause the computer to determine printing parameter values ​​(1) of an inkjet printing device (2) for printing a pattern on a surface (3) of an eyeglass lens substrate (4) including a curved surface, the inkjet printing device (2) including a print head (5) as one separate component with a plurality of print nozzles (6, 6a, 6b, 6c), the instructions causing the computer to group the plurality of print nozzles (6, 6a, 6b, 6c) into at least two print nozzle groups (10a, 10b, 10c, 10d, 10e) and to determine printing parameter values ​​(1) of at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) for each print nozzle group (10a, 10b, 10c, 10d, 10e), the print head (5) being configured not to be tilted with respect to the eyeglass lens substrate (4).

19. 1. A non-transitory computer-readable storage medium comprising: instructions, when executed by a computer, that cause the computer to determine printing parameter values ​​(1) of an inkjet printing device (2) for printing a pattern on a surface (3) of an eyeglass lens substrate (4) including a curved surface, the inkjet printing device (2) including a print head (5) as one separate component with a plurality of print nozzles (6, 6a, 6b, 6c), the instructions causing the computer to group the plurality of print nozzles (6, 6a, 6b, 6c) into at least two print nozzle groups (10a, 10b, 10c, 10d, 10e) and to determine printing parameter values ​​for at least one adjustable print parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) for each print nozzle group (10a, 10b, 10c, 10d, 10e), and the print head (5) is configured to not be tilted with respect to the eyeglass lens substrate (4).

20. 3. An inkjet printing method, in which a pattern is printed on a surface (3) of a spectacle lens substrate (4) including a curved surface by an inkjet printing device (2) including a print head (5) as one separate component with a plurality of printing nozzles (6, 6a, 6b, 6c) using printing parameter values ​​(1) of at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f), characterized in that the printing parameter values ​​(1) of the at least one adjustable printing parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) are determined according to a computer-implemented method as claimed in claim 1 or 2.

21. Inkjet printing method according to claim 20, characterized in that the tilt angle of the print head (5) with respect to the surface (3) of the spectacle lens substrate (4) is not adjusted before and / or during printing.

22. An inkjet printing device (2) for printing a pattern on a surface (3) of an eyeglass lens substrate (4) including a curved surface, comprising: a print head (5) as one single component comprising a number of print nozzles (6, 6a, 6b, 6c), a data processing system (200) including a processor (20) and a storage medium (21) coupled to said processor (20), said processor (20) adapted to determine printing parameter values ​​(1) based on a computer program stored in said storage medium (21); An apparatus comprising: the processor (20) is adapted to group the plurality of print nozzles (6, 6a, 6b, 6c) into at least two print nozzle groups (10a, 10b, 10c, 10d, 10e) and to individually determine a print parameter value (1) for at least one adjustable print parameter (7, 7a, 7b, 7c, 7d, 7e, 7f) for each print nozzle group (10a, 10b, 10c, 10d, 10e), and the print head (5) is configured not to be tilted with respect to the eyeglass lens substrate (4).

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