Communications: electrical – Land vehicle alarms or indicators – For trailer
Reexamination Certificate
1998-06-15
2001-01-23
Swarthout, Brent A. (Department: 2736)
Communications: electrical
Land vehicle alarms or indicators
For trailer
C307S010800, C315S077000, C315S082000, C340S475000
Reexamination Certificate
active
06177865
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electronic adaptor circuits which convert combined stop and turn signal lights of a trailer to operate in response to the independent stop and turn signal lights on a towing vehicle. Such devices are well known. Examples of trailer light adaptors are disclosed in U.S. Pat. Nos. 4,005,313; 4,057,310; 4,270,115; 4,405,190; 4,718,853; 4,842,524 and 4,939,503. Some of these patents disclose a circuit for adapting a three lamp system of a towing vehicle to a two lamp system of the trailer. Other patents such as U.S. Pat. Nos. 3,849,664; 3,883,845; 3,970,860; 4,006,453; 4,064,413; 4,325,052; 4,751,431; 5,030,938; 5,212,469 and 5,701,116 disclose trailer light converter systems having certain advantages. For example, U.S. Pat. No. 4,006,453 discloses a converter circuit which adapts a two lamp trailer signal light system to a three lamp towing vehicle system. In this device and others the power to drive the trailer signal lights is provided by the towing vehicle stop and turn signal lights which also serve as ground for the logic circuit. Such a design requires a complex diode isolation network. However, if the towing vehicle lights are missing or defective the logic of the converter will be defeated. Furthermore, the requisite diode isolation network in combination with output transistors, significantly reduce the power output to the trailer signal lights. In addition, many current vehicle lighting circuits employ sensors to detect defective signal lights. Connecting such signal lights to provide power to trailer signal lights causes a significant drain on the towing vehicle lights which can cause disruption of the defective lamp sensors and faulty indications.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a battery powered adaptor which enables a trailer having combined stop and turn signal light systems to be towed behind a vehicle having independent stop and turn light systems.
Another object of the invention is to provide a device having means for de-activating the stop signal lamp on one side of the trailer when the turn signal on that side is being operated.
A further object of the invention is to provide power to the trailer lights directly from a 12.5 volt battery, thus isolating the signal lamps of the towing vehicle from the signal lamps of the trailer.
A yet further object of the invention is to eliminate the need for a complex diode network and to properly operate the trailer signal lights independent of the condition of the towing vehicle signal lights in a simplified circuit for enhanced reliability.
Another object of the invention is to prevent defective lamp sensors in the towing vehicle from malfunctioning as the result of excessive current drain at the towing vehicle signal lights.
These and other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the invention with reference to the attached drawing.
REFERENCES:
patent: 3872424 (1975-03-01), Enabnit
patent: 3970860 (1976-07-01), Purdy
patent: 4006453 (1977-02-01), Bryant
patent: 4232910 (1980-11-01), Snyder
patent: 4751431 (1988-06-01), Ducote
patent: 4857807 (1989-08-01), Hargis
patent: 5498910 (1996-03-01), Hopkins et al.
patent: 5521466 (1996-05-01), Vincent
patent: 5701116 (1997-12-01), Hoekstra
Bryant Richard C.
Johnson Richard
MasoTech, Inc.
Reising Ethington Barnes Kisselle Learman & McCulloch PC
Swarthout Brent A.
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