COMPOSITE GLASS HAVING REDUCED THICKNESS FOR A HEAD-UP DISPLAY (HUD)

Abstract

A composite glass for a head-up display is described. The composite glass has an outer pane made of glass and an inner pane made of glass, which are bonded to one another via a thermoplastic intermediate layer. The inner pane has a thickness less than 1.2 mm, and the thickness of the intermediate layer in the vertical course between a lower edge and the upper edge of the composite glass is variable at least in sections with a maximum wedge angle less than or equal to 0.3 mrad.

Claims

1.-14. (canceled)

15. A composite glass for a head-up display comprising: an upper edge, a lower edge, an outer pane made of glass, and an inner pane made of glass, wherein  the outer pane and the inner pane are bonded to one another via a thermoplastic intermediate layer,  the inner pane has a thickness less than 1.2 mm, and  a thickness of the intermediate layer in the vertical course between the lower edge and the upper edge is variable at least in one or more sections, having a maximum wedge angle less than or equal to 0.3 mrad.

16. The composite glass according to claim 15, wherein the composite glass is a motor vehicle windshield.

17. The composite glass according to claim 15, wherein the outer pane has a thickness less than 2.1 mm.

18. The composite glass according to claim 17, wherein the thickness of the outer pane is from 1.2 to 2.0 mm.

19. The composite glass according to claim 15, wherein the thickness of the inner pane is from 0.3 to 1.1 mm.

20. The composite glass according to claim 15, wherein the wedge angle is less than or equal to 0.2 mrad.

21. The composite glass according to claims 15, wherein the intermediate layer is implemented by at least one thermoplastic film, and wherein the wedge angle is created by stretching.

22. The composite glass according to claim 15, wherein the intermediate layer has a minimum thickness from 0.5 mm to 1 mm.

23. The composite glass according to claim 15, wherein the intermediate layer comprises at least one component selected from the group consisting of: i) polyvinyl butyral (PVB), ii) ethylene vinyl acetate (EVA), and iii) polyurethane (PU), or mixtures or copolymers or derivatives thereof.

24. The composite glass according to claim 15, wherein the outer pane and/or the inner pane is a chemically prestressed pane.

25. A projection arrangement for a head-up display comprising: the composite glass according to claim 15 and further comprising a projector, wherein the projector is aimed at a region of the composite glass, and a thickness of the intermediate layer is variable at least in said region.

26. A method for producing a composite glass for a head-up display comprising an upper edge and a lower edge, the method comprising the steps of: (a) providing a thermoplastic intermediate layer, having variable thickness in a course between two opposing edges at least in one or more sections having a maximum wedge angle less than or equal to 0.3 mrad; (b) arranging the intermediate layer between an outer pane made of glass and an inner pane made of glass having a thickness of less than 1.2 mm, wherein said edges are oriented toward the upper edge and the lower edge; and (c) bonding the inner pane and the outer pane to one another by lamination.

27. The method according to claim 26, wherein the wedge angle is introduced into a thermoplastic film of constant thickness by stretching.

28. A method comprising: using the composite glass according to claim 15 as a windshield in a motor vehicle, wherein the composite glass is a projection surface of a head-up display.

29. The composite glass according to claim 18, wherein the thickness of the outer pane is from 1.4 to 1.8 mm.

30. The composite glass according to claim 19, wherein the thickness of the inner pane is from 0.5 to 0.9 mm.

31. The composite glass according to claim 30, wherein the thickness of the inner pane is from 0.6 to 0.8 mm.

32. The composite glass according to claim 20, wherein the wedge angle is less than or equal to 0.15 mrad.

33. The composite glass according to claim 32, wherein the wedge angle is less than or equal to 0.1 mrad.

34. The composite glass according to claim 22, wherein the intermediate layer has a minimum thickness from 0.6 mm to 0.9 mm.

Description

[0046] In the following, the invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and are not true to scale. The drawings in no way restrict the invention.

[0047] They depict:

[0048] FIG. 1 a plan view of an embodiment of the composite glass according to the invention,

[0049] FIG. 2 a cross-section through the composite glass of FIG. 1,

[0050] FIG. 3 the composite glass of FIG. 2 as a component of a projection arrangement according to the invention, and

[0051] FIG. 4 a flowchart of an embodiment of the method according to the invention.

[0052] FIG. 1 and FIG. 2 depict in each case a detail of a composite glass 10 according to the invention, which comprises an outer pane 1 and an inner pane 2 that are bonded to one another via a thermoplastic intermediate layer 3. The composite glass is provided as a windshield of a motor vehicle that is equipped with a head-up display. In the installed position, the outer pane 1 is turned toward the external environment; the inner pane 2, toward the vehicle interior. The upper edge O of the composite glass points, in the installed position, upward toward the vehicle roof (roof edge); the lower edge U, downward toward the engine compartment (engine edge).

[0053] The outer pane 1 is made of soda lime glass with a thickness of 1.6 mm. The inner pane 2 is likewise made of soda lime glass and has a thickness of only 0.7 mm. The outer pane 1 and in particular the inner pane 2 are thus significantly thinner than the panes of prior art composite glasses, which are typically in the range from 1.8 mm to 2.6 mm, in the case of windshields, customarily, 2.1 mm.

[0054] The thickness of the intermediate layer 3 increases steadily in the vertical course from the lower edge U to the upper edge O. For the sake of clarity, the thickness increase is depicted linearly in the figure, but can also have more complex profiles. The intermediate layer 3 is implemented as a single film made of PVB. In the initial state, the film was a PVB film with the standard thickness 0.76 mm. The thickness increase was introduced into the film by stretching, i.e., pulling on the lower edge U. The wedge angle α is roughly 0.1 mrad. Wedge angles of prior art compound glasses for HUDs are in the range around 0.5 mrad.

[0055] In the figure, a region B, which corresponds to the HUD region of the composite glass, is also indicated. In this region, images are to be produced by an HUD projector. By means of the wedge-shaped configuration of the intermediate layer, the two images that are produced by reflection of the projector image on the two surfaces of the outer pane 1 and of the inner pane 2 facing away from the intermediate layer 3 coincide with one another. Consequently, distracting ghost images arise to a small extent.

[0056] The low thicknesses of the outer pane 1 and the inner pane 2 result in the fact that very small wedge angles α, which can be generated without any problems by stretching, are necessary. This is significantly simpler and more economical than production of the wedge film by extrusion. Furthermore, large wedge angles frequently result in pronounced double images in transmission, which can also be avoided here.

[0057] FIG. 3 depicts the composite glass 10 of FIGS. 1 and 2 as part of a projection arrangement for an HUD. The arrangement comprises, besides the composite glass 10, a projector 4, which is aimed at a region B. In the region B (HUD region), images can be produced by the projector that are perceived by the observer 5 (motor vehicle driver) as virtual images on the side of the composite glass 10 turned away from him. The wedge angle in the region B results in surfaces of the outer pane 1 and of the inner pane 2 inclined relative to one another, by which means ghost images can be prevented.

[0058] FIG. 4 depicts a flowchart of an exemplary embodiment of the method according to the invention for producing a composite glass 10 according to the invention.

LIST OF REFERENCE CHARACTERS

[0059] (10) composite glass [0060] (1) outer pane [0061] (2) inner pane [0062] (3) thermoplastic intermediate layer [0063] (4) projector [0064] (5) viewer/motor vehicle driver [0065] (O) upper edge [0066] (U) lower edge [0067] (B) region of the composite glass/HUD region [0068] α wedge angle [0069] A-A′ section line