Communications – electrical: acoustic wave systems and devices – Plural transmitters to receiver or transmitter to plural...
Patent
1992-07-07
1993-11-16
Pihulic, Daniel T.
Communications, electrical: acoustic wave systems and devices
Plural transmitters to receiver or transmitter to plural...
367 93, G01S 1587, G01S 1504, G01S 752
Patent
active
052630064
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to a device and process for detecting the presence of a vehicle by means of an ultrasonic device. This device incorporates an ultrasonic sensor and an associated electronic transmitting and receiving circuit in which ultrasonic impulses are transmitted periodically from the sender. The reflections of these impulses are received and evaluated by the circuit. A positive presence signal is emitted if after transmission of an impulse a reflection is received within a certain period of time.
A device and a process for determining, by means of ultrasonics, spaces between objects in the air are already familiar from German Patent Document DE-A-36 21 819. In this device, which is also employed for determining the presence of vehicles, an ultrasonic impulse is periodically transmitted from the sensor in accord with the impulse-reflection process, and the reflections are received by the same sensor.
With this well-known device problems occur in ascertaining the presence of vehicles when, independently of the shape of the vehicle, especially automobiles, a positive signal is to be emitted constantly and without fail when the vehicle is sighted a certain distance from the device. The present state of the art with respect to this device does not always guarantee that certain parts of a vehicle that are set at an angle--in the vicinity of air ducts or tires, for example--send back an adequate image to the sensor, thereby rendering it possible that the presence of a vehicle, especially an automobile, is not always detected.
In addition to ultrasonic devices, other devices for determining the presence of vehicles are known. There are, for example, devices that work inductively in which an activating strip is laid under the surface of the road. There are also both passive and active infrared sensors, radar devices, and so on. But these devices too do not always determine with absolute accuracy the presence of a vehicle, or they have other disadvantages. Where sensing strips are laid under the surface, problems occur when the road surface is wet. These problems are acute when there is a sudden downpour. With infrared devices the presence of sunlight when the sun is in certain positions can lead to faulty signalling. A too weak signal can be transmitted from certain vehicles, but especially from dark colored passenger vehicles. Thus, the presence of a vehicle may not always be registered accurately. Again, radar devices are relatively expensive, although on the whole they accurately record the presence of vehicles.
The purpose of the present device is to signal the presence of a vehicle so long as that vehicle, especially any motorized vehicle, remains in a certain area. It is intended for all areas in which a vehicle is present in a given area--such as a traffic lane--and for which humans or a machine are to be informed that a vehicle is positioned within the given area. Thus the device could be implemented at drive-in counters, entry and exit points on toll roads, bridges and the like, order boards at fast food restaurants, and so on. In all such applications the device is required not merely to emit an impulse, as such devices are required to do when traffic passes (for example, at traffic lights situated at intersections, or when traffic density is to be determined; on such occasions the exact distance between the device and vehicle is of little consequence); on the contrary, its application is especially suited to situations whenever it is essential that the presence of a vehicle be accurately signalled as long as the vehicle is present, either wholly or in part, within a predetermined area.
In consequence of these requirements, and proceeding from the already familiar process and the already familiar device as designated in the opening remarks, the purpose of the invention is to improve on the already familiar device and or respectively process so that, independently of the shape and configuration of the vehicle, positive notification of the presence of a vehicle is provided with absolute certain
REFERENCES:
patent: Re30719 (1981-08-01), Mills
patent: 4403311 (1983-09-01), Tournois
patent: 4458342 (1984-07-01), Tournois
patent: 4706227 (1987-11-01), DuVall et al.
Cornaby K. S.
Pihulic Daniel T.
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