Glazing with very little double imaging
The invention relates to a curved glass pane, made of float glass, the area of a main face of which is greater than 1.5 m 2 and the product of its two depths of bending is greater than 3000 mm 2 , and such that its point located on the normal to its surface passing through its center of gravity has a radius of curvature of less than 3 m in any direction, the variation in its thickness in the longitudinal float direction being less than 10 μm over 500 mm. This pane may be assembled into laminated glazing of the automobile windshield type. Such a windshield has a very small amount of double imaging even when it is fitted into the vehicle so as to be close to the horizontal.
1. A curved glass pane, comprising float glass, which is curved in a transverse float direction and a longitudinal float direction, the transverse and longitudinal float directions being mutually orthogonal, wherein:
the curved glass plane has a main face area greater than 1.5 m 2 ;
a product of a largest depth of transverse bending and a largest depth of longitudinal bending of the curved glass pane is greater than 3000 mm 2 ;
a point located on the normal to a surface passing through the center of gravity of the glass pane has a radius of curvature of less than 3 m in any direction; and
a variation in the thickness of the glass pane in the longitudinal float direction is less than 10 μm over 500 mm.
2. The pane of claim 1 , wherein the variation in the thickness is less than 7 μm over 500 mm in the longitudinal float direction.
3. The pane of claim 1 , wherein the area of a main face is greater than 1.8 m 2 .
4. The pane of claim 1 , wherein
the product of the largest depth of transverse bending and the largest depth of longitudinal bending is greater than 6000 mm 2 , and
the point located on the normal to a surface passing through the center of gravity has a radius of curvature of less than 2 m in any direction.
5. The pane of claim 1 , wherein a thickness of the glass pane ranges from 1.1 to 2.8 mm.
6. A laminated glazing assembly, comprising at least two glass panes of claim 1 , wherein the transverse and longitudinal directions of the at least two glass panes are mutually concordant.
7. The glazing assembly of claim 6 , wherein a measured level of double imaging: through the point on the normal to a surface passing through the center of gravity; and at a viewing angle of 20°, is at most 7 minutes.
8. A windshield, comprising the glazing of claim 7 .
9. A motor vehicle, comprising the windshield of claim 8 , wherein a transverse float direction is horizontal.
10. A process for manufacturing the curved glass pane of claim 1 , the process comprising bending a pane against a solid mold to give the pane at least 50% of each of the two depths of bending.
11. The process of claim 10 , wherein a temperature of the pane at the point located on the normal to a surface passing through the center of gravity is between 590 and 615° C. during the bending.
12. The process of claim 11 , further comprising cooling directly after the bending.
13. The process of claim 10 , further comprising a gravity bending before the bending of the pane against the solid mold.
14. The process of claim 13 , wherein, during the gravity bending, a temperature of the pane at the point located on the normal to a surface passing through the center of gravity is between 610 and 640° C.
15. The process of claim 10 , wherein at least two superposed glass panes are bent simultaneously.