Communications: electrical – Land vehicle alarms or indicators – External alarm or indicator of movement
Reexamination Certificate
1995-05-04
2001-12-25
Pope, Daryl (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
External alarm or indicator of movement
C340S463000, C340S465000, C340S468000, C340S467000, C340S479000
Reexamination Certificate
active
06333687
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved system for warning travelers following a vehicle when the vehicle is traveling at a speed below a predetermined reference speed.
2. Prior Art
In certain situations, particular motor vehicles do not maintain the same speed as other motor vehicles on the roadway. This can occur, for instance, when heavy trucks climb a long incline on a highway without enough power to maintain highway speeds. Often in this situation, the truck operator will manually activate the flashing hazard lights or “flashers” to warn those following him that the vehicle is slow moving. Similarly, when a vehicle is slow moving due to disrepair or due to the operator purposely driving slowly to look for a particular street address, etc., the vehicle operator will often manually activate the flashing hazard warning lights to warn that the vehicle is slow moving.
The applicant is aware of several patents generally relating to the subject matter of this invention. U.S. Pat. No. 4,800,377, to Slade, discloses a system for actuating rear warning lights on a vehicle when the vehicle speed falls below a predetermined lower limit or threshold speed. Slade uses a magnetic pick-up to generate a pulsed signal correlating to the speed of the vehicle. This pulsed signal is compared to a reference pulse signal representing the threshold speed and, if the pulsed signal is below the reference signal, rear warning lights are flashed to warn those following the vehicle. The Slade patent provides a mechanism for enabling the operator to adjust the threshold speed if the vehicle is in slow speed conditions (city driving).
GB 2,175,462, to Hepburn, discloses a warning system that provides a visual warning whenever the vehicle is decelerating. The Hepburn patent also uses a pulsed signal to represent the speed of the vehicle.
U.S. Pat. No. 4,162,445, to Cambell, and U.S. Pat. No. 4,368,427, to Hayashi, both disclose digital speedometers. The Cambell patent uses optically generated timing pulses with a rate proportional to the rotational speed of the speedometer cable driver. The speedometer of the Hayashi patent includes a hysteresis processing circuit to improve the response of the system.
U.S. Pat. No. 3,691,525, to McClellan et al., discloses a speedometer wherein the vehicle speed is indicated to those located remotely from the vehicle through a series of lights mounted on the vehicle.
U.S. Pat. No. 3,790,932, to Ridpath, discloses a braking warning device for vehicles that is particularly adapted for snowmobiles and other vehicles that do not normally have brake lights. The Ridpath patent uses a variable output rotary generator for producing a voltage that is proportional to the vehicle speed. This voltage is compared with itself over time and is used to illuminate an external light when the vehicle is decelerating. A light is also illuminated when the speed of the vehicle falls below a predetermined rate.
U.S. Pat. No. 3,805,161, to Bayhz et al., discloses a system for sensing the speed of a motor vehicle. A pick-up coil device is used which generates an AC signal having a frequency related to the speed of the vehicle. The Bayhz et al. patent further discloses that the sensed speed may be used to provide a visual indication when a certain maximum vehicle speed is attained.
Most motor vehicles are operated in both low-speed environments (city driving) as well as high-speed environments (highway driving). While a device that automatically flashes warning lights whenever the vehicle speed is below a predetermined threshold speed is desirable in highway driving, it is often unwelcome and unnecessary in city driving when the vehicle is often being operated below the threshold speed. Thus, this is a drawback of the prior art.
A further drawback of the prior art systems is that on many vehicles, the turn signals utilize the same lights as the warning light system and when the warning lights are flashing, it is not possible for the driver to indicate a change of vehicle direction.
SUMMARY OF THE INVENTION
The present invention concerns an automatic underspeed warning system for motor vehicles that overcomes the drawbacks of the prior art systems described above when the systems are used with a vehicle employed for both city driving and highway driving.
According to a first aspect of the invention, the system is provided with a switch for selecting one of two alternative threshold or reference speeds (the speed below which the warning indicators are activated) so that one speed (e.g. 40 mph) may be selected during highway driving and a lower speed (e.g. 20 mph) may be selected during city driving.
According to a second aspect of the invention, the system can be reset so that, once reset, the warning indicators will not be activated until the vehicle first exceeds the reference speed and then falls below the reference speed. Thus, a vehicle may be operated at slower speeds (as in city driving), below the reference speed, without the warning indicators being activated, but once the vehicle attains the reference speed (as in highway driving), the warning indicators will be activated if the vehicle then slows below the reference speed.
As mentioned above, most prior-art systems utilize the vehicle's existing warning or “hazard” lights as the underspeed indicators, and this can be a problem when the driver activates his turn signals. The present invention provides a sensor for determining when the turn signals of the vehicle are activated and inhibits the activation of the warning lights during this time. This optional feature allows a driver to safely indicate to others that he is changing directions, or changing lanes.
The present invention also provides for two alternate methods of sensing the speed of the vehicle: either a magnetic-pick-up whose signal is amplified and converted to a DC signal, applicable to most vehicles, or a DC signal that is provided to a digital speedometer, applicable to vehicles having that capability. This allows the present invention to be easily adapted to modern vehicles wherein a DC speed signal is already provided.
Other features, and advantages of the present invention will be set forth in, or will become apparent from, the detailed description of the preferred embodiments of the invention which follows.
REFERENCES:
patent: 3045738 (1962-07-01), Lombardi
patent: 3500091 (1970-03-01), Jones
patent: 3581278 (1971-05-01), Huffman
patent: 3691525 (1972-09-01), McClellan, Sr. et al.
patent: 3790932 (1974-02-01), Ridpath
patent: 3805161 (1974-04-01), Bayhz et al.
patent: 3906345 (1975-09-01), Bertolasi
patent: 4162445 (1979-07-01), Campbell
patent: 4243938 (1981-01-01), Bliven, II et al.
patent: 4368427 (1983-01-01), Hayashi et al.
patent: 4800377 (1989-01-01), Slade
patent: 4841276 (1989-06-01), Abel et al.
patent: 4843370 (1989-06-01), Milde, Jr.
patent: 1801964 (1970-07-01), None
patent: 2247533 (1974-04-01), None
patent: 2175462A (1986-11-01), None
Larson & Taylor PLC
Pope Daryl
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