METHOD FOR DETERMINING THE CURVATURE OF A GLASS PANEL, IN PARTICULAR A WINDSHIELD PANEL

Description

[0001] The present invention relates to a method for determining the curvature of a glass pane, a method for determining the curvature of a windshield and a method for monitoring the production process of a windshield using one of the aforementioned methods.

[0002] Glass panes, especially windshields, are manufactured industrially, for example, using a gravity-driven forming process in which a blank is heated and, in its heated state, is forced into a mold by gravity, or using a process in which one or more heated blanks are formed by pressing. Particularly with windshields, they are increasingly being used for functions beyond their original purpose of protecting vehicle occupants from the wind. For example, it is known to use a so-called head-up display, in which information is projected onto the windshield and can be perceived by the driver through reflection. Furthermore, windshields are also used to mount sensors, especially cameras.This results in high demands on optical quality with regard to the transmission and reflection of light. Besides the parity of the glass, especially concerning inclusions and the like, the shape of the windshield is of particular importance for meeting these high demands. Therefore, determining the curvature of a windshield is becoming increasingly important.

[0003] It is known from the prior art to use three triangulation sensors configured as point sensors to record curvature data along three lines on the windshield. The term "point sensor" is understood to mean that data is recorded at a single point on the windshield. A relative movement between the point sensor and the windshield results in the recording of data along a line of the windshield. The triangulation sensor determines a distance, which, through calibration (e.g., of the sensor's position relative to a plane on which the windshield rests), yields a positional data curve from which the curvature of the windshield in this area can be determined.

[0004] Due to the constantly increasing demands on the precision of the curvature of the windshield, the data obtained in this way no longer meets certain requirements.

[0005] Methods for measuring surfaces are known from US 2016 / 379379 A1, DE 100 45 105 A1, US 2016 / 202039 A1, EP 3 635 330 B1 and US 5,726,749 A. None of these methods satisfactorily solves the problems described.

[0006] Therefore, starting from the disadvantages known from the prior art, the present invention aims to provide an improved method for determining the curvature of a glass pane.

[0007] This problem is solved by the features of the independent claim. Dependent claims are directed toward advantageous further developments. It should be noted that the features listed individually in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further detailed and explained in the description, which also presents further preferred embodiments of the invention.

[0008] The inventive method for determining the curvature of at least one glass pane, in which the at least one glass pane and a sensor device are movable relative to each other in a direction of movement, and the sensor device comprises at least three triangulation sensors, each comprising a light emission unit that emits light onto the at least one glass pane and a light detection unit that detects the light scattered by the at least one glass pane, such that position data from the at least one glass pane are recorded by the triangulation sensors, covering the at least one glass pane in the direction of movement, wherein the triangulation sensors have different positions in a transverse direction perpendicular to the direction of movement, comprising an inner triangulation sensor and at least two outer triangulation sensors formed in a transverse direction outside the inner triangulation sensor.is characterized by the fact that the external triangulation sensors record position data from at least two positions in the transverse direction.

[0009] The inventive method is particularly applicable to single glass panes, so-called singlets, but also to multiple glass panes that, for example, lie inside one another. Two nested glass panes are specifically referred to as a doublet. Windshields, in particular, are regularly manufactured from several glass panes that are bonded together. During the production process, such glass panes are typically separated by a layer of powder, but are formed together and then subjected to the subsequent production process, during which they are bonded together. Furthermore, so-called laminated windshields also exist, in which two or more singlets are bonded together.

[0010] Basically, a film is applied between two panes of glass to form a windshield, either before or during the joining process. This serves to separate the panes and can also provide additional functionalities such as shatter protection.

[0011] A triangulation sensor is a laser-based distance sensor that measures distances to a reference object with high accuracy and without physical contact. A laser beam is projected onto the object by the light emission unit (a laser source), and the scattered light is imaged at an oblique viewing angle by the light receiver unit, which typically contains a specially designed photosensitive chip, such as a CCD chip. By analyzing the resulting measurement signals, position data is obtained that precisely represents the distance of a scattering interface or object to the reference. If a specific interface is defined, it is also possible to measure thicknesses. The corresponding thickness is thus determined as the difference between two distances.

[0012] The measurement provides positional data that allows the curvature of the glass pane to be determined at the position of the corresponding triangulation sensor in the transverse direction. For each position (in the transverse direction) of a triangulation sensor, a data set is obtained that two-dimensionally represents the distance of the respective interface relative to a position in the direction of movement. This allows the contour of the glass pane in the direction of movement to be determined at the position in the transverse direction.

[0013] According to the invention, the outer triangulation sensors acquire position data from at least two positions in the transverse direction. This allows the glass pane to be measured more accurately than with methods known in the prior art. This can be achieved with minimal effort. For example, at least the outer triangulation sensors can be moved in the transverse direction. Position data can be acquired at three specific positions in the transverse direction, advantageously over the entire length of the glass pane in the direction of movement. This is followed by a transverse displacement of at least the outer triangulation sensors (or the entire sensor assembly) and subsequent acquisition of position data in the longitudinal direction. Alternatively or additionally, it is possible to use more than one outer triangulation sensor, for example, two or three.Alternatively or additionally, at least one of the triangulation sensors can be designed as a line sensor that records data over a certain length in the transverse direction.

[0014] Preferred configurations include an inner triangulation sensor configured as a point sensor and two or three outer triangulation sensors, each configured as a point sensor. A further preferred configuration includes an inner triangulation sensor configured as a point or line sensor and outer triangulation sensors configured as line sensors.

[0015] Preferably, the inner triangulation sensor records position data from only one position in the transverse direction.

[0016] In this case, the inner triangulation sensor is designed as a point sensor. As shown with reference to the figures, such a point sensor receives a two-dimensional data set as a measurement signal, from which the corresponding position(s) of one or more interfaces can be determined.

[0017] This design allows in particular the easy retrofitting of existing systems, which often already have one or more point sensors.

[0018] According to an advantageous embodiment, the procedure further comprises the following steps: i) Setting a first position of the triangulation sensors in the transverse direction; ii) Relative movement between the sensor device and the glass pane in the direction of movement, thereby recording position data by the triangulation sensors; iii) Setting a second position in the transverse direction of at least the outer triangulation sensors, different from the first position; iv) Relative movement between the sensor device and the glass pane in the direction of movement, thereby recording position data by at least the outer triangulation sensors.

[0019] In particular, the relative movements according to steps ii) and iv) represent a back-and-forth movement in the direction of motion. Thus, with a single triangulation sensor, two position data sets from two positions in the transverse direction can be acquired through two relative movements in the direction of motion, by moving the corresponding triangulation sensor between the relative movements in the transverse direction. This allows the number of positions in the transverse direction at which the curvature is determined to be doubled, even with the same number of triangulation sensors.

[0020] In this context, it is generally preferred that at least one of the outer triangulation sensors is moved at least temporarily in a transverse direction during the acquisition of position data.

[0021] This allows complex paths to be traversed on the glass pane to be measured, making it possible to measure precisely defined areas of the glass pane with regard to their curvature in a single measurement.

[0022] According to an advantageous embodiment, two or more outer triangulation sensors are provided on one side of the inner triangulation sensor.

[0023] This allows position data to be recorded simultaneously at multiple positions in the transverse direction by the outer triangulation sensors.

[0024] According to an advantageous embodiment, at least one of the following triangulation sensors is used: a) the inner triangulation sensor; and b) at least one of the outer triangulation sensors Position data from multiple positions in the transverse direction simultaneously.

[0025] This can be achieved in particular by designing the corresponding sensor as a so-called line sensor, which simultaneously records data along a line of the object being measured. This creates a three-dimensional measurement signal due to the scattering, from which the position of the corresponding interface(s) can be read.

[0026] In this context, it is particularly preferred that at least one of the following triangulation sensors: a) the inner triangulation sensor; and b) at least one of the outer triangulation sensors is designed as a line sensor, whose light emission unit emits light in a line perpendicular to the direction of movement.

[0027] Thus, the corresponding triangulation sensor simultaneously records data from multiple positions in the transverse direction. It is preferably possible to extract the position data, and therefore the curvature of the glass pane, for specific positions in the transverse direction from this data, so that the analysis can be limited to the areas of the glass pane that are particularly relevant.

[0028] Furthermore, a method for determining the curvature of a windshield is proposed, wherein at least one element of a windshield is subjected to a method according to the invention after the forming process.

[0029] This means, in particular, that for windshields made up of multiple glass panes, individual panes are measured, or several or even all panes that make up the windshield are measured simultaneously. In such a case, the triangulation sensors provide measurement data from every interface present; specifically, position data sets for the various interfaces are available, which can then be viewed and evaluated accordingly.

[0030] The described method is used in particular immediately following the forming process of the glass pane, however it is alternatively or additionally also possible to monitor the curvature of the at least one glass pane, in particular a windshield, at other times / locations of the production process.

[0031] In this context, a method for monitoring the production process of a windshield is proposed, wherein the curvature of at least one element of a windshield is determined at at least two points in time according to a method according to the invention, and the obtained curvature data are stored and correlated with each other for monitoring the production process.

[0032] Correlation refers specifically to comparison with a standard dataset and / or comparison of changes between datasets. An element in this context refers specifically to a single pane of glass that makes up the windshield, or to all the panes of glass assembled during the production process to form the windshield. This correlation of curvature data allows for the easy detection of defects in windshield manufacturing, as changes or errors affecting the curvature of the elements are immediately identified. For example, damage to the production equipment can be detected directly.

[0033] The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the illustrated embodiments, as the scope of protection of the invention is defined by the attached claims. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and / or findings from other figures and / or the present description. The figures schematically illustrate: Fig. 1 is an example of a sensor device for determining the curvature of at least one glass pane; Fig. 2 is an explanation of the measuring principle; Figs. 3 to 5 are examples of procedures for measuring the curvature of at least one glass pane; and Fig. 6 is another example of a sensor device with a corresponding procedure for measuring the curvature of at least one glass pane.

[0034] The following describes several measurement methods for measuring the curvature of at least one glass pane. Identical elements are always designated with the same reference symbols.

[0035] Fig. 1 Figure 1 schematically shows an example of a sensor device 1 for determining the curvature of at least one glass pane. The device 1 has a measuring arm 20 on which sensor holders 21 are mounted, which are movable in a transverse direction 2. At least one triangulation sensor is accommodated in or on each sensor holder 21, which is positioned with reference to Figure 2 The triangulation sensor in the respective sensor holder 21 emits a laser beam 6 onto a surface whose distance from the measuring arm 20 and / or a defined reference plane is to be determined.

[0036] Fig. 2Figure 1 schematically shows a triangulation sensor 3 comprising a light emission unit 4 and a light detection unit 5. The light emission unit 4 emits a laser beam 6 towards the surface to be measured. The laser beam 6 is directed towards a windshield 7, which consists of a first glass pane 8 and a second glass pane 9. The light beam is scattered and directed as a scattered light beam 10 towards the light detection unit 5, where a measurement signal 11 is recorded, as shown by way of example. This measurement signal 11 exhibits several peaks, which originate in particular from the signals at the interfaces of the individual glass panes 8 and 9.The laser beam 6 first passes through a first interface 12 between the ambient air and the first glass pane 8, then a second interface 13 between the first glass pane 8 and the second glass pane 9, and finally a third interface 14 between the second glass pane 9 and the ambient air. The scattering of the light results in a spectrum with different peaks in the measurement signal 11, which can be assigned to the individual interfaces.

[0037] This allows the distances of the interfaces 12, 13, 14 from a calibrated reference plane, for example, defined by the measuring arm 20 and the vector of the direction of movement 15 of a relative movement between the measuring arm 20 and the glass pane 8, 9, to be determined. Knowing the distances of the interfaces 12, 13, 14 from the reference plane at the position where the laser beam 6 strikes the interface 12, 13, 14, and correlating these distances with each other, the thicknesses of the first glass pane 8 and the second glass pane 9 can be determined.

[0038] With renewed reference to Figure 1 The following describes how sensor device 1 is made. Figure 1This can be used accordingly for determining the curvature of the windshield 7. For this purpose, a relative movement between the measuring arm 20 and the windshield 7 is effected in a direction of movement 15 by moving the sensor device 1 relative to the windshield 7 and / or the windshield 7 relative to the sensor device 1. Typically, an inner triangulation sensor 15 is aligned with a central axis 16 of the windshield 7. This allows the inner triangulation sensor 15 to acquire position data of the central axis 16 of the windshield 7.

[0039] Furthermore, two outer triangulation sensors 18 are provided, which are located on the outside of the measuring arm 20 compared to the inner triangulation sensor 17, i.e., outside the inner triangulation sensor 17, so that the inner triangulation sensor 17 is located between the outer triangulation sensors 18. The outer triangulation sensors 18 can detect position data from areas outside the central axis 16 of the windshield 7, for example, areas that are in the driver's or passenger's field of vision after the windshield 7 has been installed.Particularly in situations where a precise contour of the windshield 7 is increasingly important, corresponding measurement methods are insufficient, as more and more areas of the windshield 7 are being functionalized, for example for so-called "Head Up Displays", in which information is projected onto the windshield 7 so that the driver sees the reflection of the information in the windshield 7, or through the development of sensors or similar.

[0040] Therefore, with reference to Figure 3Another measurement method is described. Only the differences to the method described above are discussed; further details are referred to the explanations given above. Here, the measuring arm 20 also has three sensor carriers 21, but the corresponding outer sensor carriers 21 each have two outer triangulation sensors 18. This increases the number of laser beams 6 emitted by the corresponding triangulation sensors. As a result, during a single relative movement between the windshield 7 and the measuring arm 20, position data from several measurement paths, i.e., at several positions in the transverse direction 2, can be acquired, thus improving the quality of the curvature measurement in a simple manner.

[0041] Figure 4 shows another example of a measurement method, in which, unlike the one in connection with Figure 3According to the disclosed method, three outer triangulation sensors 18 are each formed on the respective sensor carriers 21. This results in three times more position data being acquired in the area of ​​the outer triangulation sensors 18 than in the example from Figure 1 .

[0042] Fig. 5 demonstrates an alternative procedure using the example of the procedure from Fig. 4 , which, however, also involve the procedures from Figs. 2 to 3The procedure can be combined with the above-described method. Only the differences from the method described above are discussed; further details are referred to the explanations above. In this case, compared to the procedures described above, the relative movement between the windshield 7 and the measuring arm 20 is modified by first performing a relative movement in the direction of movement 15, then a relative movement in the transverse direction 2 perpendicular to the direction of movement 15, and then a third relative movement opposite to the direction of movement 15. At least during the first and third relative movements, position data is recorded via the corresponding triangulation sensors 17 and 18. Thus, the windshield 7 and the measuring arm 20 are moved back and forth relative to each other. This can be achieved by a corresponding movement of the windshield 7 and / or by a corresponding movement of the measuring arm 20.Such a procedure reduces the amount of data recorded compared to the procedures according to . Figs. 2 to 4 doubled, in particular the number of recorded tracks 19, that is, the position data at a specific position in the transverse direction 2, is doubled in a simple way.

[0043] The procedure described here allows for the more precise measurement of an area that, in later operation, will serve, for example, as a projection surface for a so-called head-up display. A precisely defined curvature of the windshield 7 is particularly important here, as the curvature of the windshield 7 and its precision in this area ensure the most accurate possible representation of the data displayed in the head-up display, and deviations can easily render the windshield 7 unusable.

[0044] Fig. 6Figure 1 shows an example where three line sensors are configured as triangulation sensors 17, 18 on the measuring arm 20. These line sensors record data from a line instead of a single point. This method allows individual tracks 19 (shown here only as examples) to be selected from the data acquired by the triangulation sensors 17, 18, and their curvature is to be measured. The corresponding position data are then extracted from the total position data acquired by the respective triangulation sensor 17, 18. In principle, the triangulation sensors 17, 18 can be configured to completely cover the windshield 7 in the transverse direction 2. Reference symbol list

[0045] 1 Sensor device 2 Lateral direction 3 Triangulation sensor 4 Light emission unit 5 Light detection unit 6 Laser beam 7 Windshield 8 First glass pane 9 Second glass pane 10 Light beam 11 Measurement signal 12 First interface 13 Second interface 14 Third interface 15 Direction of movement 16 Center axis 17 Inner triangulation sensor 18 Outer triangulation sensor 19 Track 20 Measuring arm 21 Sensor holder

Claims

1. Method for determining the curvature of at least one glass pane (7, 8, 9), in which the at least one glass pane (7, 8, 9) and a sensor device (1) are movable relative to each other in a direction of movement (15) and the sensor device (1) has at least three triangulation sensors (3, 17, 18), each having a light emission unit (4), which respectively emits a laser beam (6) onto the at least one glass pane (7, 8, 9), and a light detection unit (5), which detects the light scattered by the at least one glass pane (7, 8, 9), such that the triangulation sensors (3, 17, 18) record position data from the at least one glass pane (7, 8, 9) that cover the at least one glass pane (7, 8, 9) in the direction of movement (15), wherein the triangulation sensors (3, 17, 18) have different positions in a transverse direction (2) transverse to the direction of movement (15), with an inner triangulation sensor (17) and at least two outer triangulation sensors (18) formed in the transverse direction (2) outside the inner triangulation sensor (17), characterized in that the outer triangulation sensors (18) record position data from in each case at least two positions in the transverse direction (2).

2. Method according to Claim 1, in which the inner triangulation sensor (17) records position data from only one position in the transverse direction (2).

3. Method according to one of the preceding claims, comprising the following steps: i) defining a first position of the triangulation sensors (17, 18) in the transverse direction (2); ii) relative movement between the sensor device (1) and the glass pane (7, 8, 9) in the direction of movement (15), while position data are recorded by the triangulation sensors (17, 18); iii) setting a second position, which differs from the first position, in the transverse direction (2), at least of the outer triangulation sensors (18); iv) relative movement between the sensor device (1) and the glass pane (7, 8, 9) in the direction of movement (15), while position data are recorded by at least the outer triangulation sensors (17, 18).

4. Method according to one of the preceding claims, in which at least one of the outer triangulation sensors (18) is moved at least temporarily in the transverse direction (2) while capturing position data.

5. Method according to one of the preceding claims, in which two or more outer triangulation sensors (18) are each formed on one side of the inner triangulation sensor (17).

6. Method according to one of the preceding claims, in which at least one of the following triangulation sensors: a) the inner triangulation sensor (17); and b) at least one of the outer triangulation sensors (18) records position data from a plurality of positions in the transverse direction (2) at the same time.

7. Method according to Claim 6, in which at least one of the following triangulation sensors: a) the inner triangulation sensor (17); and b) at least one of the outer triangulation sensors (18) is in the form of a line sensor whose light emission unit (4) emits light in a line transverse to the direction of movement (15).

8. Method for determining the curvature of a windscreen (7), wherein at least one element (7, 8, 9) of a windscreen (7) is subjected to a method according to one of the preceding claims after the moulding process.

9. Method for monitoring the production process of a windscreen (7), wherein the curvature of at least one element (7, 8, 9) of a windscreen (7) is determined at least two times according to a method according to one of the preceding claims, and the curvature data obtained are kept and the curvature data are correlated with each other for the purpose of monitoring the production process.