GLASS PANE OF A VEHICLE GLAZING HAVING A PRINT

Abstract

A glass pane of a vehicle glazing, wherein the glass pane has a print containing scattering particles that scatter light, and wherein light coupled in at the side of the glass pane is coupled out via the print by means of the scattering particles. According to the invention, the glass pane has a curvature or a critical curvature which excludes reversible deformation of the glass pane into a planar configuration, and wherein the print formed with a printing ink in a digital printing process is situated over part of the surface, or the entire surface, of the outer curvature or the inner curvature of the glass pane.

Claims

1. A glass pane of a vehicle glazing, where the glass pane has a print containing light-scattering particles, and where light coupled laterally into the glass pane is outcoupled via the print by the light-scattering particles, wherein the glass pane has a curvature or critical curvature that rules out reversible deformation of the glass pane to a planar configuration and in that the print formed by a printing ink in a digital printing method is disposed over part of the area or the whole of the area on the outer curvature or the inner curvature of the glass pane.

2. The glass pane as claimed in claim 1, wherein the glass pane has a curvature in which the ratio between a curvature height across curve edges that bound the curvature and the size or length or width of the curved glass pane between the curve edges is in the range from 1:50 to 1:10 and/or in that a critical curvature of the glass pane is assigned a critical stress in the cross section of the glass pane of greater than 80 MPa when the glass pane is deformed from its curved configuration to a planar configuration.

3. The glass pane as claimed in claim 1, wherein the glass pane has a curvature with a curvature height across curve edges that bound the curvature in the range from 15 mm to 120 mm.

4. The glass pane as claimed in claim 1, wherein the printing ink is transparent.

5. The glass pane as claimed in claim 1, wherein the print has at least one area subregion in which the printing ink has been applied in individual spaced-apart ink droplets.

6. The glass pane as claimed claim 1, wherein the print has been formed with at least one planarily printed area subregion or as a printed full area with printing ink applied over the whole area.

7. The glass pane as claimed in claim 5, wherein a printed area subregion has a texture established in an aftertreatment of the print by laser irradiation of an edge of the printed area subregion.

8. The glass pane as claimed in claim 1, wherein the glass pane has been primed for the print applied.

9. A method of producing a glass pane of a vehicle glazing and having a print containing light-scattering particles, comprising: outcoupling light coupled laterally into the glass pane via the print by the scattering particles, providing a glass pane having a curvature or having a critical curvature that rules out reversible deformation of the glass pane to a planar configuration, applying the print formed by a printing ink containing the light-scattering particles over part of the area or the whole of the area on the outer curvature or the inner curvature of the glass pane, and applying the printing ink in a digital printing method.

10. The method as claimed in claim 9, wherein, in the digital printing method, a printhead is moved relative to the curved glass pane at a defined printing distance from the surface of the curved glass pane to be printed.

11. The method as claimed in claim 9, wherein the glass pane has regions with different curvatures and in that the printhead is moved at a greater printing distance in a region of the glass pane with high curvature by comparison with a region of the glass pane with lower curvature, in which the printhead is moved at a smaller printing distance.

12. The method as claimed in claim 9, wherein an edge of a printed region is reworked or resharpened by irradiating or lasering.

13. The method as claimed in any of claim 9, wherein, at least in a subarea of the print or a printed subarea region, applying the printing ink is by applying individual spaced-apart ink droplets.

14. The method as claimed in claim 9, further comprising priming the glass pane, in the regions to be printed, for the printing ink to be applied.

15. The method as claimed in claim 14, wherein the priming is made by applying of an adhesive to the glass pane, by a spray adhesive, or of a surface alteration or surface cleaning of the glass pane.

16. The method as claimed in claim 15, wherein the surface cleaning of the glass pane is by a laser roughening or plasma treatment of the glass pane.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0035] The invention is elucidated in detail by an embodiment of a curved glass pane printed by a digital printing device, with reference to the drawing. The figures show:

[0036] FIG. 1 a cross-sectional view in a schematic diagram of a curved glass pane with a print and with a digital printing device for production of the print on the glass pane;

[0037] FIG. 2 a cross-sectional view in a schematic diagram of a vehicle glazing in the form of a composite pane formed with a printed glass pane;

[0038] FIG. 3 an enlarged top view of a portion of the glass pane with print applied;

[0039] FIG. 4 a cross-sectional view of a heat-strengthened glass pane, showing tensile stresses and compressive stresses;

[0040] FIG. 5 an isometric view of a deformed glass pane on a support.

DETAILED DESCRIPTION

[0041] A curved glass pane 1 (FIG. 1) has a print 3 on its outer curvature 2. The print 3 has been produced by means of printing ink and applied by a digital printing device 4 to the outer curvature 2 of the glass pane 1. The glass pane 1 has a curve height 5 between the inner curvature 6 of the glass pane 1 in the middle of its curve 7 and a straight line 8 interconnecting two opposite outer edges 9 of the glass pane 1. The outer edges 9 of the glass pane 1 are also the curve edges 10 of the curvature of the glass pane 1 when the glass pane 1 in its entirety has the curvature. If only a portion of the glass pane 1 has such a curvature, the curve edges 10 may differ from the outer edges 9. The curvature shown in the glass pane 1 is illustrative and serves for elucidation. The glass pane 1 may also be curved in two or more directions or about two or more axes (see x axis and y axis in FIG. 5).

[0042] The curve height 5 is, for example, between about 1.5 cm and 12 cm. The length of the straight line 8 between the curve edges 10 of the curvature of the glass pane 1 or between the opposite outer edges 9 of the curved glass pane 1 is, for example, roughly between 50 cm and 180 cm.

[0043] The ratio between the curve height 5 and the curve edges 10 of the curvature is preferably within a range from, for example, 1:10 to 1:50.

[0044] A critical curvature of the glass pane 1 has a ratio between the curve height 5 and the curve edges 10 of the curvature of at least 1:50 and especially 1:10. A critical curvature is such a significant curvature that rules out reversible deformation of the glass pane 1 to a planar configuration owing to expected breakage of the glass.

[0045] A vehicle glazing 11 (see FIG. 2) contains such a curved and printed glass pane 1 and is especially formed with a second glass pane 12 as a composite glass pane. The vehicle glazing 11 is, for example, part of a vehicle roof.

[0046] The curved glass pane 1 may have been printed with the print 3 over the whole area. On the other hand, the print 3 may also have been produced from multiple printed area subregions 13 (FIG. 3). Such area subregions 13 may be spaced apart from one another or else be in contact with one another or merge into one another. The area subregions 13 may have any desired shapes and may have an irregular distribution or a pattern arrangement. In particular, such an area subregion 13 is a pictogram, a logo or else an alphanumeric symbol.

[0047] An edge 14 or a border of such a printed area subregion 13 can be refined and contoured by an aftertreatment, especially by laser irradiation. This aftertreatment is appropriate especially when the printing ink has run at the edge 14. By means of a laser beam, printing ink at nonsharp edge or border lines of the ink layer is burnt away thermally, such that the edge 14 is sharpened.

[0048] For printing of the glass pane 1, the digital printing device 4 is disposed on the side facing the outer curvature 2 of the glass pane 1 (FIG. 1). The digital printing device 4 has a printhead 15 for printing of the curved glass pane 1. The printhead 15 is mounted so as to be movable relative to the glass pane 1 by means of a bearing device 16. A control device is provided, which actuates the bearing device 16 in such a way that it keeps the printhead 15 at a defined printing distance and/or angle from the surface of the glass pane 1 to be printed. The control device, by means of data representing the surface geometry of the glass pane 1, controls a motor drive of the bearing device 16. The control device preferably contains at least one sensor 17 which detects the printing distance and/or the angle of the printhead 15 from the surface of the glass pane 1 to be printed and permits closed-loop control or path correction.

[0049] The bearing device 16 has a printhead carrier 18 which is moved in an x-y plane across the surface of the glass pane 1 and is movable in z direction relative to the surface of the glass pane 1. The printhead 15 may be mounted pivotably on the printhead carrier 18 about a pivot axis 19 aligned at right angles to the z axis. On the other hand, the printhead 15 may also be disposed in a fixed manner on the printhead carrier 15, and the printhead carrier 18 may be mounted pivotably about a pivot axis 20 aligned at right angles to the z axis. Finally, it may also be the case that the printhead 15 is mounted pivotably on the printhead carrier 18 about the pivot axis 19 which is aligned at right angles to the z axis, and the printhead carrier 18 is mounted pivotably about the pivot axis 20 which is aligned at right angles to the z axis.

[0050] Preferably, in the course of printing of the surface of the glass pane 1, multiple sensors 17 detect the surface of the glass pane 1 and especially the curvature of the glass pane 1, where the control device, by means of the sensor data, aligns the printhead 15 in its respective position vertically with respect to the surface of the glass pane 1 and keeps it at the defined printing distance.

[0051] Appropriately, a drying unit 21 is provided, which is mounted on the bearing device 16 and assigned to the printhead 15, and tracks the printhead 15. The drying unit 21 is preferably mounted on the printhead carrier 18 in a fixed or movable manner, for example by means of a pivot joint or pivotable about a pivot axis 22. On the other hand, the drying unit 21 may also have an independent movable and adjustable mount.

[0052] The drying is preferably effected by UV light. A UV source is disposed on the printhead 15, which tracks the printhead 15. The intensity of the UV irradiation is preferably such that the printing ink adheres in a first step and is cured in a further step, for example including in a separate curing chamber. It may be the case here that, after the adhesion, testing of the printed image and of the print takes place and, in the case of an improper print or printed image, the print is at least partially removed.

[0053] In another method, it is possible with the aid of a UV source to cure the printing ink immediately after the local application.

[0054] The digital printing device 4 may be formed either as a gantry robot or as a robot with a robot arm movable about several axes.

[0055] An inventive glass pane 1 is, for example, a heat-strengthened glass having a thickness d of 1.4 mm to 2.5 mm, preferably of 1.8 mm to 2.2 mm and especially of 2.1 mm. In the curved glass pane 1, by known thermal treatment in the production thereof, compressive stresses god have been generated in the glass material thereof on the outer face over the cross section thereof, and tensile stresses .sub.0,z in the interior (see FIG. 4). The compressive stress generated is, for example, up to a maximum of about 40 MPa. The curved glass pane 1 is placed on a planar support 23 (FIG. 5) and a load is applied centrally until all edges 24 of the glass pane 1 are in contact with the support 23 with initial deformation. The further application of stress is effected, for example, by means of multiple suction cups (not shown), which are distributed in the support 23 and deform the glass pane 1 into a completely planar configuration on the support 23. The compressive stresses are transformed to tensile stresses by the bending of the glass pane 1. In the deformation, especially at the edge 24 of the glass pane 1, cracks occur, which can lead to breakage of the glass. Such cracks occur especially in the case of tensile stresses of greater than 40 MPa. The tensile stresses at the edge should therefore not be greater than, for example, 40 MPa, in order to avoid breakage of the glass. In the case of deformation of the glass pane from its curved configuration to the planar configuration, stresses in the glass material of 40 MPa (compressive stress .sub.0,d) to +40 MPa (tensile stress .sub.0,z), i.e. a total stress or a change in stress of less than 80 MPa, may thus be permissible before the glass pane could break. Larger changes in stress exceeding 80 MPa are thus critical changes in stress assigned to a critical curvature, which designate the glass pane 1 to be printed for the printing of the invention.

TABLE-US-00001 List of reference numerals 1 glass pane 2 outer curvature 3 print 4 digital printing device 5 curvature height 6 inner curvature 7 middle of curve 8 straight line 9 outer edge 10 edge of curve 11 vehicle glazing 12 second glass pane 13 area subregion 14 edge 15 printhead 16 bearing device 17 sensor 18 printhead carrier 19 pivot axis 20 pivot axis 21 drying unit 22 pivot axis 23 support 24 edge