WINDSHIELD
FIG4 is a side view showing the positional relationship between a head-up display device and a windshield  FIG3 is a cross-sectional view of an interlayer
In order to prevent this, at least the display region of the windshield 1 onto which light is projected by a HUD device 500 is formed such that the thickness decreases downward as shown in FIG4. As a result, light that is reflected off the inner surface of the windshield 1 and then enters the inside of the vehicle and light that is reflected off the outer surface of the windshield and then enters the inside of the vehicle mostly match and the problem of generation of a double image is resolved. It should be noted that the wedge angle α of the windshield 1 in this case can be set to 0.01 to 0.04° (0.2 to 0.7 mrad), for example, although the wedge angle is set depending on the installation angle of the windshield 1.  The interlayer 13 is constituted by at least one layer, and can be constituted by three layers, namely a soft core layer 131 and outer layers 132 that are harder than the core layer 131 and between which the core layer 131 is sandwiched as shown in FIG3, for example. However, the interlayer is not limited to this configuration, and may be constituted by a plurality of layers including the core layer 131 and at least one outer layer 132 that is arranged on the outer glass plate 11 side. For example, the interlayer 13 may be constituted by two layers, namely the core layer 131 and one outer layer 132 arranged on the outer glass plate 11 side. Alternatively, the interlayer 13 may be configured by arranging an even number of outer layers 132 on each side of the core layer 131 so that the core layer 131 is located at the center. Alternatively, the interlayer 13 may be configured by arranging an odd number of outer layers 132 on one side of the core layer 131 and arranging an even number of outer layers 132 on the other side so that the core layer 131 is sandwiched therebetween. It should be noted that if only one outer layer 132 is provided, the outer layer 132 is provided on the outer glass plate 11 side as described above, which is for the purpose of enhancing the breakage resistance performance with respect to an external force from the outside of a vehicle or a building. Moreover, when the number of outer layers 132 is increased, the sound insulation performance is improved.
cross-sectional view, side view
4
Aspect
500
device
132
outer layer outer layers
3
horizontal direction. Aspect
13
interlayer
['1. A windshield that has a display region onto which information is projected using light emitted from a head-up display device, the windshield comprising: an outer glass plate; an inner glass plate that is arranged opposite to the outer glass plate; and an interlayer that is arranged between the outer glass plate and the inner glass plate, wherein lattice points are defined at a pitch of no greater than 20 mm in the display region, and when wedge angles at the lattice points are measured using an interferometer with 240 × 240 pixels or more, a difference between the largest value and the smallest value of the wedge angles is no greater than 0.32 mrad.']