Illumination – Supported by vehicle structure – Plural light sources
Reexamination Certificate
1998-09-23
2001-09-25
Sember, Thomas M. (Department: 2875)
Illumination
Supported by vehicle structure
Plural light sources
C362S249070, C362S800000
Reexamination Certificate
active
06293687
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to circuits with light emitting diodes, for motor vehicle indicator lights. It also relates to motor vehicle indicator lights which include such circuits.
BACKGROUND OF THE INVENTION
Conventionally, a motor vehicle indicator light such as an indicator light for giving signals to other traffic, of the kind in which the light source consists of light emitting diodes, the diodes are carried on a substrate which is for example a printed circuit, and a regulating circuit is provided which mainly consists of a power resistor, the regulating circuit being mounted away from the light emitting diodes. One example of this kind of light is described in U.S. Pat. No. 5,325,271.
It has recently been proposed to provide a structure for an indicator light using light emitting diodes which enables the remote regulating circuit to be omitted. That proposed solution consists of incorporating in the network of light emitting diodes crosswise resistors, each of which is associated with one of the diodes and connected in series with the latter. One such circuit is shown in
FIG. 1
of the accompanying drawings. In
FIG. 1
the resistors are indicated by the reference numeral
1
, while the diodes are indicated by the reference numeral
2
.
Such a structure eliminates problems related to the wires that connect the substrate carrying the light emitting diodes with the regulating circuit consisting of the power resistor. However, that arrangement is still not fully satisfactory. In particular, the proximity of the resistors and the light emitting diodes gives rise to excessive heating of the diodes. This in turn results in a substantial reduction in their performance, giving a loss of emission in the order of 40%.
SUMMARY OF THE INVENTION
One object of the invention is to propose an alternative solution which has the same advantages in terms of cost and quality as structures of the kind shown by way of example in
FIG. 1
, but without having the disadvantages.
According to the invention, a light emitting diode circuit for a motor vehicle indicator light, including a support such as a printed circuit, on which a network of light emitting diodes is implanted together with two power supply wires connected to the network, is characterized in that at least one of the wires is a resistive wire having a linear resistance greater than 1 ohm per meter, the length of each resistive wire being such that the said wire regulates the power supply current for the light emitting diodes.
The invention also provides a motor vehicle light with light emitting diodes, characterized in that it includes a circuit according to the invention.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of a preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.
REFERENCES:
patent: 4641251 (1987-02-01), Inoue
patent: 5038255 (1991-08-01), Nishihashi et al.
patent: 5062027 (1991-10-01), Machida et al.
patent: 5207492 (1993-05-01), Roberts
patent: 5325271 (1994-06-01), Hutchisson
patent: 0 695 907 (1996-02-01), None
Nicholson and Xu, Engineering Design Guide, 3rd Edition, p. 11, 1992.*
French Search Report dated Jun. 5, 1998.
Hamzaoui Azedine
Poirot Pascal
Morgan & Finnegan , LLP
Sember Thomas M.
Valeo Electronique
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