Tunnel sensor
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Jun 5, 2001
Grant Date -
N/A
app pub date -
Mar 31, 1999
filing date -
Nov 17, 1997
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A sensor (20, 100, 200, 300) for detecting the approach and exit of a vehicle (42) to a tunnel (46). In one embodiment there is a sensor (20, 100, 200, 300) with a photodiode (22a) that receives light through an inclined channel (30, 30') or aperture (32, 332, 432). The channel provides a field of view (44, 344, 31) ahead and above the vehicle. The photosensor (22a) is thus sensitive to the change in light from this field of view (44, 344, 31) as a vehicle enters (46a) and exits (46b) a tunnel (46). Some embodiments of the present invention include a second photosensor (22b) with a wider field of view (112, 112', 111) for detecting ambient light.
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- Non-US Classification not provided for expired patents
Cited Art Landscape
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- Citation Ranking not provided for expired patents
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