U.S. patent application number 09/121844 was filed with the patent office on 2002-07-04 for laminated glass windscreen intended to be used at the same time as a hud system reflector.
Invention is credited to SAUER, GERD.
Application Number | 20020086141 09/121844 |
Document ID | / |
Family ID | 7836776 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020086141 |
Kind Code |
A1 |
SAUER, GERD |
July 4, 2002 |
LAMINATED GLASS WINDSCREEN INTENDED TO BE USED AT THE SAME TIME AS
A HUD SYSTEM REFLECTOR
Abstract
A laminated safety glass windscreen, which can also be used as a
reflector in a HUD system, comprises at least first and second
panes and a thermoplastic intermediate layer which joins these
panes together. The cross-section of the intermediate layer is in
the shape of a wedge, decreasing in thickness from top to bottom.
The thermoplastic intermediate layer may be composed of two sheets,
one of which is provided with a colored filtering strip and has a
wedged cross-section conditioned by the appearance of this
filtering strip. The other sheet has a wedged cross-section such
that the two sheets together have the prescribed convergence angle
for using the windscreen as a reflector.
Inventors: |
SAUER, GERD; (STOLBERG,
DE) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
7836776 |
Appl. No.: |
09/121844 |
Filed: |
July 24, 1998 |
Current U.S.
Class: |
428/156 |
Current CPC
Class: |
Y10T 428/31616 20150401;
B32B 2250/02 20130101; Y10T 428/24612 20150115; B32B 17/10761
20130101; B32B 17/10036 20130101; G02B 2027/0121 20130101; B32B
17/10339 20130101; B32B 17/10568 20130101; Y10T 428/24479 20150115;
Y10T 428/2495 20150115; B32B 17/1066 20130101; G02B 27/0101
20130101; Y10T 428/31601 20150401; B32B 17/10005 20210101; B32B
2367/00 20130101 |
Class at
Publication: |
428/156 |
International
Class: |
B32B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 1997 |
DE |
19731873.8 |
Claims
1. A laminated glass windscreen having a taper angle for a
reflector in a HUD system, comprising: (i) a first pane, (ii) a
second pane, and (iii) a intermediate layer having a wedge-shaped
cross-section, between said first and second panes, comprising (a)
a first thermoplastic sheet comprising a tinted filtering strip at
an upper edge of said first thermoplastic sheet, and (b) a second
thermoplastic sheet, on said first thermoplastic sheet, wherein
said second thermoplastic sheet has a wedge-shaped
cross-section.
2. The laminated glass windscreen of claim 1, wherein said first
thermoplastic sheet has a taper angle of 0.
3. The laminated glass windscreen of claim 1, wherein said first
thermoplastic sheet has a wedge-shaped cross-section.
4. The laminated glass windscreen of claim 1, wherein said
intermediate layer further comprises a support sheet comprising a
functional layer, between said first thermoplastic sheet and said
second thermoplastic sheet.
5. The laminated glass windscreen of claim 1, wherein said first
thermoplastic sheet comprises a polymer selected from the group
consisting of polyvinyl butyral and polyurethane.
6. The laminated glass windscreen of claim 1, wherein said second
thermoplastic sheet comprises a polymer selected from the group
consisting of polyvinyl butyral and polyurethane.
7. The laminated glass windscreen of claim 5, wherein said second
thermoplastic sheet comprises a polymer selected from the group
consisting of polyvinyl butyral and polyurethane.
8. The laminated glass windscreen of claim 1, wherein said first
thermoplastic sheet comprises polyvinyl butyral, and said second
thermoplastic sheet comprises polyvinyl butyral.
9. The laminated glass windscreen of claim 4, wherein said support
sheet comprises polyethylene terephthalate.
10. A method of making the laminated glass windscreen of claim 1,
comprising: laminating said first pane, said intermediate layer and
said second pane.
11. The method of claim 10, further comprising, prior to said
laminating, stretching to form said first thermoplastic sheet with
a wedge-shaped cross-section.
12. The method of claim 10, further comprising, prior to said
laminating, extruding to form said second thermoplastic sheet in a
wedge shape.
13. The method of claim 11, further comprising, prior to said
laminating, extruding to form said second thermoplastic sheet in a
wedge shape.
14. The method of claim 10, further comprising, prior to said
laminating, stretching to form said second thermoplastic sheet with
a wedge-shaped cross-section.
15. The method of claim 11, further comprising, prior to said
laminating, stretching to form said second thermoplastic sheet with
a wedge-shaped cross-section.
16. A method of making the laminated glass windscreen of claim 4,
comprising: laminating said first pane, said intermediate layer and
said second pane.
17. A method of displaying an image, comprising: projecting an
image on the laminated glass windscreen of claim 1.
18. A method of displaying an image, comprising: projecting an
image on the laminated glass windscreen of claim 4.
19. A vehicle, comprising the laminated glass windscreen of claim
1.
20. A method of displaying an image, comprising: projecting an
image on a windscreen of a vehicle, wherein said windscreen is the
laminated glass windscreen of claim 1, and reflections of said
image from said first pane and said second pane appear superimposed
to a driver of said vehicle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention:
[0002] The present invention relates to a laminated glass
windscreen having a predetermined taper angle and intended to be
used at the same time as a reflector in a HUD system.
[0003] 2. Discussion of the Background:
[0004] It is known that the reflection of light rays from the
surfaces of glass increases with the angle of incidence. In the
case of windscreens which are fitted with a large angle of
inclination, objects situated inside the vehicle and below the
windscreen are visible to the driver in the windscreen, which acts
as a mirror. This effect can be exploited, for example by
projecting optical information onto the windscreen. In this regard,
however, ordinary windscreens with parallel faces present the
problem that the light rays, which are reflected both by the
interior surface and by the exterior surface of the windscreen,
present the observer with two images which are offset relative to
one another.
[0005] It is known from EP 0 420 228 B1, hereby incorporated by
reference, that this problem of double images can be avoided by
using an intermediate layer with a wedge-shaped cross-section which
makes the two reflecting surfaces of the windscreen form an angle
such that the two reflected images appear superimposed to the
driver's eyes. In this way, not only is a relatively sharp
reflected image obtained, but the clarity of the image is also
enhanced. However, the taper angle required of the intermediate
layer for this purpose depends strongly on the angle at which the
windscreen is fitted and on the position of the image projector in
the vehicle, and therefore needs to be carefully adapted to each
particular situation.
[0006] It is also known to use a thermoplastic intermediate sheet
with a tinted filtering band during the manufacture of curved
windscreens made of laminated glass with a filtering strip along
the upper edge. The desired curvature of the filtering strip is
then obtained by intentional irregular stretching of the sheet.
This stretching, involving plastic deformation of the sheet, is
carried out in order to adapt the profile of the filtering strip to
that of the upper part of the laminated windscreen. Stretching in
the shape of a circular arc leads to a taper on the long side of
the curvature, which gives a sheet with a wedge-shaped
cross-section. The taper angle of a sheet stretched in this way is
determined by the radius required for the filtering strip.
Therefore, the thermoplastic sheet with wedge-shaped cross-section
formed in this way does not normally have the taper angle needed
for a windscreen to be used as a reflector in a head-up display
(HUD) system comprising two reflection surfaces which form a
determined angle in order to superimpose the images.
SUMMARY OF THE INVENTION
[0007] An object of the invention is to provide a laminated glass
window which contains a tinted filtering strip integrated with the
thermoplastic intermediate sheet, whose curvature is adapted to
that of the upper edge of the laminated glass pane and whose two
panes also form, relative to one another, an angle such that they
serve as a reflector in a head-up display system, resulting in two
reflected images which are superimposed with a view to enhancing
brightness and avoiding a double image.
[0008] This object is achieved with an intermediate layer
comprising at least two thermoplastic sheets, one of which is
provided along its upper edge with a tinted filtering strip, and
the other has a wedge-shaped cross-section such that the two sheets
together have the desired taper angle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Various other objects, features and attendant advantages of
the present invention will be more fully appreciated as the same
becomes better understood from the following detailed description
when considered in connection with the accompanying drawings in
which like reference characters designate like or corresponding
parts throughout the several views and wherein:
[0010] FIG. 1 is a front view of a windscreen with a tinted
filtering strip, and FIG. 2 is a view in section on the axis II-II
in FIG. 1.
[0011] FIG. 3 is a view in section on the axis II-II in FIG. 1, of
an embodiment different from that of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0012] A laminated glass window according to the invention has the
advantage that the two reflecting surfaces can be arranged relative
to one another with a predetermined taper angle, with a view to
using the windscreen as a reflector in a HUD system, irrespective
of the taper angle already presented by the thermoplastic sheet
with the incorporated tinted filtering strip.
[0013] It is also possible for the laminated glass windscreen to
have a straight edge at the filtering strip. In this case, the
sheet comprising the filtering strip does not need to be stretched,
and consequently no longer has a wedge-shaped cross-section. The
required taper angle is then produced only by the other sheet.
[0014] According to a further advantageous embodiment of the
invention, a support sheet comprising a functional layer is placed
between the thermoplastic sheets which together form the defined
taper angle. This support sheet may, for example, be made of
polyethylene terephthalate (PET) and be provided with a coating
which reflects infrared wavelengths, but is transparent to other
wavelengths.
[0015] The taper angles required of the thermoplastic sheets may be
obtained by stretching with plastic deformation, but it is also
possible to use sheets originally extruded with a wedge-shaped
cross-section. The sheet provided with the tinted filtering strip
may itself also be extruded with a wedge-shaped cross-section.
[0016] When the sheets are being drawn to give them the necessary
radii of curvature, which may be as little as 2 m, it is clearly
necessary to take care that the two sheets together have a minimum
thickness in order to retain a safety functions and adhesion
properties. A person of ordinary skill in the art can easily select
a suitable thickness for the sheets.
[0017] A variety of commercially available polymer sheets may be
used as thermoplastic sheets which together are to form the
determined taper angle. In particular, polyvinyl butyral and
polyurethane sheets are suitable.
[0018] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
[0019] Referring to FIG. 1, the windscreen 1 is provided along its
upper edge with a tinted filtering strip 2. As illustrated in FIG.
2, this windscreen may be produced with a taper angle .theta. in
order to ensure superimposed reflection of an image by the exterior
surfaces 31 and 61 of the panes 3 and 6. In this example, the taper
angle .theta. is selected to be 0.5 mrad.
[0020] At its upper edge, the laminated glass windscreen 1 has a
radius R.sub.1 of 3.30 m, and its height h is 0.80 m. The
thermoplastic sheet 4 comprising the tinted filtering strip 2 is
made of polyvinyl butyral (PVB). Initially, it has an overall
thickness and, after drawing on its upper edge, of 0.76 mm
(d.sub.1). From the geometrical ratios and prescribed data, it is
possible to deduce the taper angle k.sub.1 which is obtained by
stretching the PVB sheet 4 with the desired radius of curvature
R.sub.1, using the formula: 1 k 1 = d 1 R 1 + h
[0021] where d.sub.1 is the initial thickness of the sheet, R.sub.1
is the radius of curvature at the upper edge, and h is the height
of the sheet, which gives k.sub.1=0.185 mrad.
[0022] In order to obtain the required taper angle .theta. of 0.5
mrad, it is necessary to add a second thermoplastic sheet 5, also
made of PVB, having a taper angle k.sub.2 of 0.315 mrad, such that
0.5 mrad-.theta.=k.sub.1+k.sub.2. For an initial thickness
d.sub.2=1.52 mm of the second sheet, the relation: 2 R 2 = d 2 k 2
- h
[0023] gives, for this sheet, a required stretching radius of 4.025
m.
[0024] The two stretched thermoplastic sheets 4 and 5 are arranged
in such a way that the taper angles k.sub.1 and k.sub.2 are added
to give the stipulated angle of .theta.=0.5 mrad. The sheets are
then assembled in the conventional way with the curved panes 3 and
6 to form a laminated glass windscreen which exhibits the required
taper angle of 0.5 mrad.
[0025] The specific values R.sub.1, h, and d.sub.1 are easily
selected by those of ordinary skill in the art, and in part depend
on dimensions of the specific vehicle in which the windscreen is
intended to be used. As an example, R.sub.1 may be 2-4 m, h may be
0.40-1.6 m, and d.sub.1 may be 0.10-2.50 mm. Similarly d.sub.2 may
be 0.10-2.50 mm.
[0026] A third sheet may be included, such as a support sheet
comprising a functional layer between the thermoplastic sheets.
Such an embodiment is illustrated in FIG. 3, where the support
sheet 7, is between the thermoplastic sheets 4 and 5.
[0027] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
[0028] The priority document of the present application, German
Patent Application No. 197 31 873.8, filed on Jul. 24, 1997, is
hereby incorporated by reference.
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