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Simultaneous head-up display windshield wedge-angle and layer-thickness measurements
| Content Provider | Semantic Scholar |
|---|---|
| Author | Marcus, Michael B. |
| Copyright Year | 2016 |
| Abstract | Automotive head-up display (HUD) systems include a projector that projects light onto the windshield. This light is then reflected into the driver’s eyes and appears as a virtual image on top of the hood of the car, at a comfortable viewing distance from the driver.1 The image source of the HUD projector, however, emits multiple rays of light at different angles from a common origin. For example, the light that is reflected into the driver’s eyes from the inner and outer air interfaces of the windshield creates the virtual image and a ghost image, respectively, and results in a double image. The windshield comprises laminated safety glass made from two layers of glass that are bonded together with one or more layers of polyvinyl butyral (PVB). Most windshields are not simple flat structures, but include slight curvatures in both the horizontal and vertical dimensions. The ghosting problem is illustrated in Figure 1(a) for standard windshields that have no wedge angle. The green and red lines show the paths of light from the image source, reflecting off the inner and outer windshield–air interfaces, respectively, into the driver’s eye to form the virtual and ghost images. The virtual and ghost images do not overlap, therefore, the image is blurred, as shown on the left of Figure 1(a). To eliminate this ghosting effect, the angular separation between the virtual and ghost images must be less than the angular resolution of the human eye, which is about 0.2mrad. A PVB interlayer with a small, constant wedge angle is normally used to eliminate the ghost image for a driver at a defined location.2 The optimum wedge angle is dependent on the location of the driver’s eyes, as well as the mounting angle, thickness, and curvature of the windshield.3 This use of a PVB interlayer with a small wedge angle causes the virtual and ghost images to overlap, resulting in a sharp image, as shown on the left of Figure 1. (a) A head-up display (HUD) system projecting through a windshield with no wedge angle gives rise to a double ghost image, as shown on the left. (b) The same system projecting through a windshield with a wedge angle ( ̨) gives rise to a sharp image, as shown on the left. PVB: Polyvinyl butyral. |
| File Format | PDF HTM / HTML |
| DOI | 10.1117/2.1201607.006610 |
| Alternate Webpage(s) | http://www.spie.org/documents/Newsroom/Imported/006610/006610_10.pdf |
| Alternate Webpage(s) | https://doi.org/10.1117/2.1201607.006610 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
