Illumination – Supported by vehicle structure – Plural light sources
Reexamination Certificate
2002-04-16
2004-09-07
Sember, Thomas M. (Department: 2875)
Illumination
Supported by vehicle structure
Plural light sources
C362S548000, C362S549000
Reexamination Certificate
active
06786625
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to lamps for motor vehicles and more particularly to direct current light-emitting diode (LED) lamps and more particularly to LED lamp modules containing control circuitry for producing light of high intensity usable as a tail, brake, or turn signal lamp.
2. Background
The features of the present invention are particularly useful as applied to the construction of LED lamp modules to replace incandescent lamps used in automobiles and other motor vehicles and are applicable to the manufacture of LED replacement bulbs for both single filament and dual filament incandescent bulbs. LED's typically operate at voltages between 1.7 and 2.2 volts. Overvoltaging and overheating of LED's result in significant degradation of the performance and lifetime of LED's. One well known type of existing incandescent lamp generally employs a type S-8 glass bulb cemented in a double-contact brass bayonet base. A second type of incandescent lamp has a similar bulb inserted into an insulated plastic wedge base that is adapted to fit into a corresponding plastic socket. A type of incandescent bulb with a wedge base is described in U.S. Pat. No. 4,603,278 (Devir et al.). Incandescent vehicle signal-lamp bulbs consume a relatively large amount of power, generate a large amount of heat and have a relatively short life.
LED bulbs designed to replace vehicle incandescent bulbs require bases similar to the standard bayonet or the wedge bases. To be effective an LED bulb must be adapted to produce an intense light when viewed by the human eye and must provide for effective heat dissipation to avoid impairing the LED's. It also must be designed to operate within the range of voltages present in motor vehicles so as to not over-voltage the LED's. Finally, some models of motor vehicles ground the brake circuit when the brake is not activated to prevent any accidental activation of the brake lights; accordingly, an effective LED bulb designed to replace a dual filament bulb must contain circuitry enabling the LED's to be activated with either the tail lamp circuit or the brake light circuit.
One approach to solving the problems of cooling the LED's is given in U.S. Pat. No 5,632,551 (Roney et al.) which describes an LED bulb as used in truck trailers and/or tractors. The LED's are mounted on a printed circuit board (PCB). The LED's are embedded in resin to facilitate the conduction of heat away from the LED's so that the heat will not cause the LED's to degrade and lose brightness. This bulb is not designed to fit in standard automotive lamp sockets.
A second approach to the cooling problem is given by U.S. Pat. No. 5,575,459 (Anderson) which describes an AC LED bulb that uses air holes to provide air circulation and cooling for an LED bulb. This bulb is not suitable for motor vehicle use.
U.S. Pat. No.6,045,240 (Hochstein) presents a third solution to the problem of cooling the LED's by teaching the use of a heat sink to cool an LED array. This is not a bulb, but a lamp assembly; therefore it is not suitable for replacing an incandescent light bulb.
One type of LED bulb with a wedge base is described in U.S. Pat. No. 5,160,200 (Cheselske). It provides a parallel string of LED's soldered and rolled up for 2-volt dc operation. The roll is placed in a housing with two leads extending out the wedge type base. No provisions are made for 12-volt operation, dual element operation, voltage control, heat dissipation, or brightness enhancement. The wedge is not suitable for motor vehicle wedge type sockets, because it differs in size and shape from the automotive standard. Additionally, it does not have the required fasteners for motor vehicle applications. It is also limited in the number of LED's which may be contained and therefore the brightness because of the cylindrical shape specified for the body. A funnel shaped body is more desirable for automotive applications. Typical LED's are 1.7 to 2.2 volts dc. If this bulb were connected to vehicle voltage of 12 to 14 volts dc, the LED's will burn out.
U.S. Pat. No. 5,947,588 (Huang) describes an LED bulb where an LED array is mounted on a printed circuit board which is in turn mounted on a standard automotive bayonet type base. The LED's are directly connected to the electrical contacts on the bayonet base. The patent shows an embodiment of the bulb to replace a dual filament bulb. The patent does not describe the circuit connections of the LED's to the contacts, but either the LED's are grouped into two sets-one for use as tail lights and a second for use as brake lights—or the LED's are connected in parallel so that all LED's are illuminated when either the tail light or the brake light circuit is energized. If the LED's are grouped in the two sets then all of the LED's cannot be energized at once resulting in dimmer tail light and brake lights. On the other hand, if the circuits are connected in parallel so that all LED's would be energized if either tail lamp or brake lamp circuit were energized, the array would not work as tail lamps in automobiles in which the brake lamp is grounded when the brake is not activated. Also, if this configuration did work in some vehicles, the tail lamps and the brake lamps would be illuminated with equal intensity, that is the brake lights would not be brighter. The patent discusses the problem of low intensity by suggesting the addition of more LED's; this would make the array larger than a standard incandescent lamp which in turn would result in the LED lamp being unable to fit into many tail lamp assemblies. Also, this configuration of LED bulb will not fit into many recessed automotive sockets and lamp assemblies.
Voltage varies from vehicle to vehicle from a low of 10-volts to high of 14.5 volts. In the LED bulb of U.S. Pat. No. 5,947,588, the LED's will dim in low voltage situations or worse, burn out in over voltage situations, both of which are undesirable. No means is provided for controlling the voltage and current. This lack of control causes the brightness to vary according to the vehicle voltage. It is well known that most vehicles' batteries are 12-volts dc when fully charged. They are less than 12 volts when undercharged. Most vehicles charging systems produce in excess of 12-volts de and typically between 13 and 14 volts. With applied voltage spread evenly divided across a plurality of LED's in the instant bulb without control circuitry there will be a very noticeable difference in brightness at low voltage situations and in over voltage condition on the LED's at the higher voltage extreme. Whereas incandescent bulbs are not susceptible to damage due to the over voltage situations nor do they dim down excessively at under voltage conditions, LED's by nature lose brightness disproportionately to the reduced voltage when operated below their typical specified operating voltage. On the other hand, LED's can only handle their specified maximum voltage without degradation or failure.
It is desirable to produce a light bulb that has a plurality of light-emitting diodes (LED's) which can be illuminated all at once and in a controlled way so as to have a different brightness for brake and tail light applications connected to a conventional bayonet or plastic wedge-type base so as to replace conventional single or dual filament incandescent bulbs. Neither U.S. Pat. No. 5,160,200 (Cheselske) nor U.S. Pat. No. 5,947,588 (Huang) provide a way of controlling the brightness of the LED array in different applications.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an LED replacement bulb for incandescent light bulbs, which is adapted for use in all standard vehicle sockets.
It is further an object of the present invention to
Garvey, Smith, Nehrbass & Doody LLC
Jam Strait, Inc.
Negron Ismael
Nehrbass Seth M.
Sember Thomas M.
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