Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Patent
1991-01-02
1996-09-03
Healy, Brian
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
359629, 359619, 359 13, 359 15, G02B 2714
Patent
active
055529356
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an optical device for reflecting data in the form of displays into the field of vision of the driver of a motor vehicle.
BACKGROUND
There are many suggestions for displaying relevant data to the driver of a motor vehicle by means of a head-up display (HUD). Measured data and warning signals of importance for the driver are reflected onto a portion of the windshield which lies within the field of vision of the driver. This enables the driver to recognize data, such as speed, safe brake operation or traffic information, even if his attention is directed to the traffic situation and without having to remove his eyes from the road. The need for distance adjustment by the eyes of the driver is eliminated to a large extent.
Head-up displays require a partially transparent mirror for superimposition of the virtual image generated by the data elements on the image of the environment. A reflection on the windshield or on an additional plate (combiner) placed inside of the windshield can be used for this in a motor vehicle. In both cases reflections appear at the planes of separation between the windshield or the combiner plate and the air, which result in undesirable double images and in this way considerably impair the legibility of the data. The entry of light into the optical space of the HUD results in reflections which are also blended into the field of vision of the driver. A bright, fog-like background surface appears for the driver, which hampers the view of the traffic situation. To suppress these effects, coating of the inner boundary surface with the dielectric layer is generally suggested, by means of which one of the reflected images is enhanced and the other attenuated.
It is furthermore known to design the reflecting layers in such a way that they only reflect light of the wavelength given off by the indicator elements disposed within the dashboard. The effect of ambient light can be reduced thereby.
It is furthermore known from German Patent DE-PS 33 47 271 to polarize the luminous flux and to deflect it in the direction of the driver from a multiple coating with different refractive indices applied to the windshield, taking the Brewster angle into consideration. The application of dielectric coatings by vacuum evaporation or sputtering in high vacuum, in particular on the windshield, is very expensive. It is known that these coatings are also very sensitive to scratches and dirt, so that the legibility of the displays is impaired.
THE INVENTION
Briefly in accordance with the invention polarization filters are used, which are simple and inexpensive to manufacture and provide a good contrast of the displays on the windshield. It is also an advantage that they are scratchproof and can be easily replaced in case of possible damage. Advantageously, the transmission of light in the direction of the road is only minimally hampered by the use of shutters.
The use of a second shutter in the luminous flux is particularly advantageous, because interfering scattered light is stopped down to the greatest extent possible. Disposition of the filter plates on a pivotable combiner inside of the windshield is advantageous, if it is intended to make the angle of vision and brightness of the displays variable. The virtual image can also be adjusted for drivers of different height by pivoting the combiner, so that in an advantageous manner maximum contrast is always achieved within the Brewster angle. It is also advantageous to combine, preferably transparent, liquid crystal displays with the virtual image on the combiner, because by means of this, important vehicle data, which can be displayed very clearly together with traffic information, such as engine or vehicle speed, can be reflected with a high degree of contrast into the field of vision of the driver.
A further advantage is that because of their thin walls the filter foils or plates can be very easily embedded inside the windshield in connection with composite glass without noticeable distracting reflectio
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WPI Abstract of DE-05 33 47 271 Wiesmeier & Reiniger/Daimler-Benz AG (No date of publication).
Knoll Peter
Konig Winfried
Mock-Hecker Rudiger
Healy Brian
Robert & Bosch GmbH
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