Abstract:
An enhanced control mechanism for an LED light string system is provided for switching between one of two DC output phases or polarities so as to actuate one or the other of two LEDs within the bulbs on the light string. The control mechanism is further configured to allow switching so as to pass through the input power provided by a light string that is plugged into its electrical power feeding end. The control mechanism may provide either AC, rectified AC, or DC voltage of various values to the LED string according to the particular needs of the LED bulbs.

Description:
RELATED APPLICATIONS 
     This application claims priority to the U.S. Provisional Patent Application Ser. No. 61/296,258, titled “Adapter for Coordinating Illumination of Multi-Color LED Lighting String Displays”, filed on Jan. 19, 2010; and the U.S. Provisional Patent Application Ser. No. 61/460,048, titled “Apparatus and Method for LED Light String Connection”, filed on Dec. 23, 2010, the contents of all of which are herein incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The disclosure relates generally to a multi-color light emitting diode (LED) light string and more specifically, to a controller for coordinating the illumination of the different color LED lights; the lights being contained within a single light string or among several interconnected LED light strings. 
     BACKGROUND OF THE INVENTION 
     Various LED light strings have been proposed for decorative illumination purposes. U.S. Pat. Appln. Pub. No. US2009/0189533 (Hsu), for example, discloses an LED-based light string formed with multiple, dual colored LED lamps and a controller for coupling the LED light string to the power supply. According to one preferred embodiment in Hsu, FIG. 4 discloses a light string in which two LED lamps of different colors are set within a single body. The body is shown to have two connection leads, and the two LED lamps are electrically connected within the body such that one LED lamp illuminates when a positive DC voltage is applied to the two leads of the body and the other LED lamp illuminates when a negative DC voltage is applied to the two leads of the body. Multiple bodies are then electrically connected in series so as to create a single string of LED lights. Claim 3 of Hsu further states that the controller can control only one or the other of the two LEDs within the body to emit a single color, or can control both alternately to emit both colors. However, Hsu does not disclose any structure or mechanisms for accomplishing these control functions. 
     Other arrangements of the LEDs within light strings are also known. U.S. Pat. No. 6,461,019 (Allen) discloses a LED light string in which a plurality of LEDs are wired in block series-parallel where one or more series blocks are each driven at the same input voltage as the source voltage and the series blocks are coupled in parallel. Allen also mentions that the individual LEDs of the light string may be arranged continuously (using the same color) periodically (using multiple, alternating CIP colors), or pseudo-randomly (any order of multiple colors). However, Allen does not provide for any control functions regarding the illumination of different colored LED within those arrangements. 
     Thus the need exists to provide for a LED light string controller that is capable of controlling and coordinating the specific illumination of the LEDs within the string, particularly with respect to the control of color. Further, one master LED light controller would ideally provide such control functions in an arrangement containing multiple LED light strings, while the controllers for the other light strings followed or mirrored the color selection made by master controller. 
     SUMMARY OF THE INVENTION 
     According to one particularly preferred embodiment of the invention a lighting system is provided comprising a light string, the light string having bulbs containing a first color LED and a second color LED, the LEDs within the bulbs electrically coupled so that a first voltage phase applied to the light string provides a turn-on bias to the first color LEDs within the bulbs and a second voltage phase applied to the light string provides a turn-on bias to the second color LEDs within the bulbs; and a controller electrically coupled to one end of the a light string, the controller having a rectifier for accepting an input electrical power source and providing an output DC electrical power to the light string, the controller having a switch with a plurality of switch positions including: a first switch position for providing the output DC electrical power to the light string in the first voltage phase according to a first rectification provided by the rectifier within the controller, a second switch position for providing the output DC electrical power to the light string in the second voltage phase according to a second rectification provided by the rectifier within the controller, and a third switch position for providing the input electrical power source directly to the output DC electrical power and on to the light string. 
     According to other aspects of the lighting system, the controller includes a fourth switch position that provides no output DC electrical power to the light string; or the rectifier is a low voltage AC-to-DC converter; or the rectifier is a full-wave bridge rectifier; or the input electrical power source is a DC power source; or a socket is connected to another end of the light string; the controller and the socket having indicators for identifying a polarity of the LED light string; or the lighting system includes a plurality of the light strings and coupled controllers; only one of the controllers having the switch in either of the first or the second switch positions; the other controllers having the switch in the third switch position. 
     In another preferred embodiment of the invention, a controller is provided for controlling a LED light string, the controller comprising a rectifier for accepting an input electrical power source and providing an output DC electrical power to the LED light string, the controller having a switch with a plurality of switch positions including: a first switch position for providing the output DC electrical power to the LED light string in a first voltage phase according to a first rectification provided by the rectifier within the controller, a second switch position for providing the output DC electrical power to the LED light string in a second voltage phase according to a second rectification provided by the rectifier within the controller, and a third switch position for providing the input electrical power source directly to the output DC electrical power and on to the LED light string. In one aspect of this embodiment, the controller includes a standardized plug end for connection to the LED light string, the standardized plug end having only one coupling orientation. 
     In a preferred method according to the invention, a method of providing switched control to a lighting system is provided comprising: coupling a first and second controller to a first and second LED light string respectively, coupling the second controller to the first LED light string so that input power to the second controller is provided by the first LED light string; switching the first controller to provide DC rectified power at a power output of the first light string, the DC rectified power derived from an input power source to the first controller and provided as the input power to the second controller; and switching the second controller to a pass through mode wherein the DC rectified power is provided directly to the second LED light string. In one aspect of this method, the steps include coupling a third controller to a third LED light string; coupling the third controller to the second LED light string so that input power to the third controller is provided by the second LED light string; and switching the third controller to a pass through mode wherein the DC rectified power output of the second light string is provided directly to the third LED light string. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. Like references indicate similar elements among the figures and such elements are illustrated for simplicity and clarity and have not necessarily been drawn to scale. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein: 
         FIG. 1  is a circuit diagram of an LED light string system according to one embodiment of the present invention; 
         FIG. 2  is a circuit diagram of an LED light string system according to an alternative embodiment of the present invention; 
         FIG. 3  is a diagram of a portion of an LED light string system according to an additional alternative embodiment of the present invention; 
         FIG. 4  is a side view of a separable controller for use with an LED light string system according to one embodiment of the present invention; 
         FIG. 5  provides a diagram illustrating a practical application of the LED light string system according to the teachings of the present invention; 
         FIG. 6  provides another diagram illustrating a practical application of the LED light string system according to the teachings of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is often desirable to have multiple LED light strings connected together for use as a lighting display or as part of such a display, such as on a Christmas tree or holiday decoration. In many displays it is also desirable for a lighting string to display a first color (e.g. clear or white) and then discontinue that displayed color in favor of a second color (e.g. blue or a plurality of other colors). In the case of color coordination and switching, it is also desirable to effect such changes easily and in a relatively simple manner. Specifically, the use of a single control point is desirable in larger lighted displays where multiple LED light strings are connected together and color change is to be effected among all such interconnected strings. 
     With reference to  FIG. 1 , a LED light string system  10  is provided containing a controller  20  and a plurality of LED light strings  70 . The light string(s)  70  may be organized in any feasible arrangement given the power supply capabilities of the controller  20 . As shown in  FIG. 1 , two blocks of series connected LEDs  82  and  84  are wired in parallel between electrical connectors  72  and  74 . As shown, each block of series connected LEDs contains a plurality of bulbs  86  each containing two LEDs  92  and  94  of two different colors. By way of the example shown in  FIG. 1 , the “W” and “M” designations next to the LEDs in the bulbs refer to “white” (clear) and “multi-colored” (e.g. blue) respectively. Resistor  88  is optionally included in each series block to provide a current limiting function within the series. Within each bulb, LEDs  92  and  94  are electrically connected to one another anode-to-cathode and cathode-to-anode such that a DC bias voltage applied across connectors  72  and  74  will turn on only one of the LEDs within each bulb. Further, the light string series are arranged such that a DC bias voltage applied across connectors  72  and  74  will turn on simultaneously all the similarly colored LEDs within each light string (i.e. either all white LEDs in the each light string or all colored LEDs in each light string). Connectors  72  and  74  are terminated at female plug end  90 . 
     Controller  20  is electrically coupled to connectors  72  and  74  at connection points  22  and  24  respectively. Controller  20  has male plug leads  32  and  34  for plugging into a standard 115V AC receptacle or into the female plug end of another LED light string system. Fuses  40  are provided in series with associated electrical connectors coupled to male plug leads  32  and  34  which are then connected to a rectifier  50  at rectifier terminals  52  and  54  respectively. Four-position switch  60  is connected at one side to rectifier terminals  52 ,  54 ,  56  and  58  as shown and as further described below. Four-position switch  60  is connected at the other side to connectors  72  and  74  at connection points  22  and  24  respectively. 
     As shown, and strictly by way of example, rectifier  50  is a full-wave bridge rectifier having rectifier terminals  52 ,  54 ,  56  and  58 . Although the operation of full-wave bridge rectifiers is well known to those of skill in the art, a brief description follows. In practice, almost any rectifier (e.g. full-wave, half-wave) or other AC/DC converter can be used operate in circuit position  50  so as to provide a single phase DC voltage at rectifier connection points  56  and  58 . The term rectifier is used herein to denote any such device, without limitation, that provides such a function. In operation, an input AC voltage is applied across full-wave bridge rectifier terminals  52  and  54 . During one half of the AC power cycle the two diodes on the left-hand side of the bridge are forward biased and the two diodes on the right-hand side of the bridge are reverse biased thereby making a half wave rectification (having a DC component in one phase) available at rectifier terminals  56  and  58 . During the other half of AC power cycle the two diodes on the right-hand side of the bridge are forward biased and the two diodes on the left-hand side of the bridge are reverse biased thereby making another half wave rectification (having a DC power component in the same one phase) also available at rectifier terminals  56  and  58 . It should be noted that if the output connection to rectifier terminals  56  and  58  is reversed, full wave rectification (the sum of the two half wave rectifications described above) would be provided in the second (other) phase such that the DC power component has an opposite polarity of that of the first phase. 
     Four-position switch  60  may be any type of electrical switch capable of making four different connections on the input (switched) side and providing the switched output at connection points  22  and  24 . For example, rotary switches, four-position slide switches multiple-push, cycling button switches may all be used for such purposes. As indicated in  FIG. 1 , the four-position switch has two inputs as provided at terminals  62  and  64  from one of four labeled switch positions A, B, C, D. In switch position A (both switch levers—as shown by dashed lines), rectifier terminals  56  and  58  are connected to the switch output and connection points  24  and  22  respectively. In switch position B (both switch levers), the rectifier terminals are reversed and rectifier terminals  56  and  58  are connected to the switch output and connection points  22  and  24  respectively. In switch position C (both switch levers), the rectifier terminals are bypassed entirely and the switch output and connection points  22  and  24  are connected directly to the power input provided to male plug leads  32  and  34  respectively. In switch position D (both switch levers), no connection to a power input is provided and connection points  22  and  24  remain unpowered and electrically disconnected. 
     In operation, AC electrical power is provided at male plug leads  32  and  34 . With the switch positioned at A, full wave rectification is provided at rectifier terminals  56  and  58  in a first phase (polarity) and passed on to connection points  22  and  24 . The first phase DC voltage is conducted through the LED light string coupled across connectors  72  and  74  and all of the positively biased LEDs within each of the bulbs are illuminated. If the LEDs are arranged as described above, then a single (same) color LED will be illuminated in each of the bulbs in each of the series blocks (i.e. all W LEDs or all M LEDs will be illuminated). With the switch positioned at B, full wave rectification is provided at rectifier terminals  56  and  58  in a second phase (opposite polarity of the first phase) and passed on to connection points  22  and  24 . The second phase DC voltage is conducted through the LED light string across connectors  72  and  74  and all of the positively biased LEDs within each of the bulbs are illuminated. If the LEDs are arranged as described above, then a single (same) color LED will be illuminated in each of the bulbs in each of the series blocks, but the LEDs other than those illuminated with the first phase DC voltage applied (i.e. if the W LEDs were illuminated by the first phase DC voltage then the M LEDs will be illuminated by the second phase DC voltage and vice-versa). With the switch positioned at C, no rectification is provided and the input AC (or DC) power provided at male plug leads  32  and  34  is passed directly on to connection points  22  and  24 . If the input power is AC then both sets of LEDs (W and M) will light alternately as biased by the appropriate phase of the AC power cycle. In essence, the AC input power simultaneously provides two different DC power components, having two different phases, to the LEDs so that both LEDs appear to illuminate simultaneously. In practical application, the “flicker” that is taking place electrically through the alternation of the phases is likely to be imperceptible to the human eye and the light string will have the appearance of having all the LEDs, W and M, on simultaneously. On the other hand, if the input power is DC with the switch in position C, then only one set of LEDs (W or M) will illuminate depending on the phase of the DC input as described above with respect to switch position A and B. Finally, with the switch positioned at D, no input power is provided to connection points  22  and  24  and all the LEDs remain off. 
     Switch position C can be termed the “follower” position particularly when the DC input to the LED light string system is provided by another (predecessor) LED light string system coupled to plug leads  32  and  34 . In this arrangement of series-connected LED light string systems, LEDs (W or M) of the second light string system will follow those illuminated in the first light string system resulting in a uniform illumination color across all such “follower configured” LED light string systems. To aid with this coordination of color matching, polarity dots  21  and  91  are provided on controller  20  and female plug end  90  respectively. Thus, if the polarity dots of consecutively connected LED light string systems are matched at each plug interface and the switch setting of the second and all subsequent LED light string systems are at C, the same polarity will be maintained at the same terminals of each string and all the same color LEDs (W or M) will illuminate in unison throughout the entire plurality of light string systems according to the switch setting of the controller on the first LED light string system. 
     Those of skill in the art will appreciate that numerous convoluted lighting schemes may be achieved by switching controllers to different settings (i.e. not necessarily switching all follower LED light strings to a “following” position C) at different points in the series of connected LED light string systems. 
     Although the physical construction and electrical circuit layout of  FIG. 1  have been specifically disclosed, those of skill in the art will appreciate that alternative physical constructions and electrical arrangements may exist to accomplish the above-described functions without departing from the teaching of the present invention. Referring to  FIG. 2 , a low voltage AC/DC converter  150  may be substituted for the full-wave bridge rectifier  50 . In one particularly preferred embodiment, a 12 or 24 volt DC output is provided by the low voltage AC/DC converter. Further, battery  105  may provide the input DC power for LED light string system  110  and the battery may be charged by optional solar cell  107 . Referring to  FIG. 3 , four-position switch of controller  220  may be replaced with an integrated circuit  261  and associated circuitry (all within integrated circuit switch complex  260 ) wherein the integrated circuit is cycled through the four inputs with a push-button switch  263 . Alternatively or in addition, remote control capability may be added for switching the controller. Wireless receiver/transmitter head  265  may be included in controller  220  for coordinating wireless communication with remote  277  having its own wireless receiver/transmitter head  275 . Push-button switch  273  on the remote is used to switch among the controller switch positions in this embodiment and wireless signals exchanged between the receiver/transmitter heads  265  and  275  include switch position information and convey switch transition information for interpretation and execution by integrated circuit switch complex  260  and the wireless remote processor  279 . Finally, the controller  20  may be removed from male plug leads  32  and  34  (which may be part of a typical AC male plug) and located at different positions within the LED light string cord. Alternatively, and referring to  FIG. 4  the controller  320  may be an entirely separate component of the LED light string system for configurable connection to any one of a number of power inputs and LED light strings to be controlled. In one particularly preferred embodiment, the female plug end  90  is replaced by standardized connector  393  (shown as a screw-in connection in  FIG. 4 ) that automatically maintains proper polarity alignment via a connector capable of only a single coupling orientation. A cap piece  333  may be provided so as to be mateably connected with the male plug ends to allow for chaining LED light string systems in series. 
     In practical application, referring to  FIG. 5 , the LED light string systems of the present invention may be used on any type of holiday decorations, such as Christmas trees  401 , wreaths  402 , and other lighted holiday ornamentation  403 . Each of these may require one or more LED light string systems to achieve the desired lighting effect. Dual color LED bulbs  486  controlled by controllers  420  may operate independent of each other as shown in  FIG. 5 , or they may be interconnected and properly switched at each controller to achieve a more coordinated effect as shown in  FIG. 6 . As shown there, a master controller  521  may be switched to setting A or B while all other controllers  520  may be switched to setting C to “follow” the polarity and presumably the color scheme selected by the master controller. All the “follower” LED light strings do not necessarily have to be of the same color or even a coordinated color depending on the desired lighting effect design, but interconnection of all the LED light strings ensures that “follower strings” have the capability of matching the LED color (through DC voltage phase pass through as selected by the master controller). 
     While the invention has been shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims.