US 20070164683 A1
An improved decorative light string circuit comprises full bridge rectification located in or downstream of the front plug, wherein the rectification circuit contains one or more voltage reducing and/or filtering elements in order to reduce or limit LED drive current and reduce (filter) DC ripple and 1 or 2 LED series sets. Additional rectification circuits and LED series sets can be added in parallel to the first in “stacked mode”, with each rectification circuit and LED series set electrically independent of prior and subsequent circuits. This eliminates the rectifying diode current summation load restrictions imposed by prior art and associated safety hazard due to diode overheating.
1. An LED light string comprising:
an AC input voltage input having a positive terminal and a negative terminal;
parallel conductor wires electrically connected to the positive and negative terminals of the AC voltage input;
a first rectification and control circuit defines a full wave rectifier comprising four rectifying diodes electrically connected to the parallel conductor wires;
a series conductor wire electrically connected to ends of each of said four rectifying diodes of said first rectification and control circuit, said ends of each of said four rectifying diodes being connected at discrete locations along said series conductor wire to provide full wave rectification;
a plurality of series connected LED lamps electrically connected by said series conductor wire.
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The present invention relates to the field of decorative LED light strings and particularly an improved circuit to be used to connect LED light strings having one or more series connection.
LEDs are becoming increasingly popular as a light source in decorative and Christmas lights due to their reliability, energy savings, longevity, and cool operation. Manufacturers of decorative light strings are constantly working to maximize the brightness and benefits of LEDs as a light source as well as reduce production cost to narrow the gap between traditional, incandescent and LED light string cost.
It is known in the art the use of a DC power supply to power LED lamps maximize LED brightness and longevity. However, prior art discloses the use of a full bridge rectification circuit that requires additional conductor wires, separate enclosures to house rectifying diodes and/or additional conductor connections and/or voltage and current reducing devices, and places undue current load on rectifying diodes, detracting from the appearance of the light string and creating a potential safety hazard.
According to the embodiment of
In addition, both of the light string designs shown in
In view of the disadvantages of the prior art, the object of the present invention is to provide an improved decorative light string circuit that can solve the problems mentioned previously.
To attain the aforesaid object, the present invention comprises a common decorative light string current tap or plug, a common end connector, full bridge rectification consisting of 4 rectifying diodes and at least 1 block of series connected LED lamps. Individual rectifying diodes form electrical connections between parallel and series conductors at various points within the light string. Said individual rectifying diodes can be distributed and housed among the light string plug, end connector, decorative light string lamp husks, or attached directly to the LED electrical contacts or conductor wires (or any combination thereof), simplifying the manufacturing process and rendering them invisible and thus eliminating the manufacture, enclosing, and electrically insulating of the 4 diode set and multiple conductor connections required of prior art
Additional LED series sets can be added in parallel to the first using traditional series/parallel light string construction and assembly methods. This eliminates the rectifying diode current summation load restrictions imposed by prior art and associated safety hazard due to diode overheating and further simplifies the light string manufacturing process.
In addition, since each bridge and LED series circuit is electrically independent parallel connected series blocks of LEDs can have varying number of serially connected LEDs within the same light string. For example series block #1 could have 75 LED lamps in series with parallel connected series block #2 having only 25 LED lamps in series and parallel connected series block #3 having 50 LED lamps in series.
Manufacturing cost is significantly reduced and light string appearance improved as the number of conductor wires does not increase as the number of LED series blocks connected in parallel increases. The prior art shown in
This invention, as well as its advantages will become apparent to one of ordinary skill in the art upon review of the included description and figures.
Reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used herein to describe the same.
As shown in
First rectifying diode (110) forms an electrical connection between parallel conductor wire (103) via optional resistor (120) and the positive terminal of first light emitting diode (130). Subsequent light emitting diodes are electrically connected in series via series conductor wire (104) through last series connected light emitting diode (133). Second rectifying diode (111) forms an electrical connection between the negative terminal of last light emitting diode (133) and parallel conductor wire (103) via optional resistor (120), thus giving half wave rectification to the partially completed circuit.
Third rectifying diode (112) forms an electrical connection between parallel conductor wire (105) via optional resistor (120) and the negative terminal of second series connected light emitting diode (131). Fourth rectifying diode (113) forms an electrical connection between the negative terminal of next to last series connected light emitting diode (132) and parallel conductor wire (105) via optional resistor (120), thus completing the circuit and providing full bridge rectification.
Optional series resistors (121) can be added in order to drive the serially connected LED lamps at the desired current. A varistor, capacitor, current saturated transistor, current limiting diode (CLD) or other impedance device can be substituted for one or more of resistors (120 and 121).
As shown in
A physical embodiment of the circuit diagram shown in
These figures are not meant to be all inclusive and are provided to illustrate to light string manufacturers how all or partial individual rectifying diodes can be incorporated within or attached to standard, commonly used lighting string components without alteration or modification of the components, or requiring fabrication of additional enclosures, thus allowing manufacturers to follow the assembly process traditionally practiced by the decorative lighting industry.
Naturally, the polarity of components and series connected LEDs can be reversed. Positive DC connections were illustrated first for consistency of illustration only.
It is to be understood that the above-referenced arrangements are illustrative of the application of the principles of the present invention. It will be apparent to those of ordinary skill in the art that numerous modifications can be made without departing from the principles and concepts of the invention as set forth in the following claims: