Patent Publication Number: US-11035530-B2

Title: Colorful light beads for a light string

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of co-pending U.S. patent application Ser. No. 15/848,994, filed Dec. 20, 2017 by the same inventor, which is a divisional of U.S. patent application Ser. No. 15/843,820, filed on Dec. 15, 2017 by the same inventor, both of which claim foreign priority to China Utility Model Application No. 201621400939.8, filed on Dec. 20, 2016 by at least one common inventor, and claim foreign priority to China Utility Model Application No. 201621400228.0, filed on Dec. 20, 2016 by at least one common inventor, and claim foreign priority to China Utility Model Application No. 201621400941.5, filed on Dec. 20, 2016 by at least one common inventor. All of the foregoing applications are incorporated by reference herein in their respective entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates generally to light strings, and more particularly to a light sting having controllable multi-color light beads. 
     Description of the Background Art 
     At present, a conventional light bulb  100  may only change in dual-color. For example,  FIG. 1  shows front and top structural schematic views of a dual-cup, dual-color light bulb  100 , which has two light-emitting chips and provided inside of the package structure. The working mechanism is that when the power supply applies the positive half-cycle of an AC current, the first light-emitting diode (LED)  102  is turned on and a second LED  104  is turned off. Conversely, when the power supply applies the negative half-cycle of an AC current, LED  104  is turned on whereas LED  102  is turned off, thereby achieving the dual-color change of the light bulb  100 . The light output options of conventional light bulb  100  are very limited. 
     SUMMARY 
     The present invention overcomes the problems associated with the prior art by providing a light string having a plurality of colorful light beads, where each of the light beads are capable of at least a seven-color change, so that the whole light string provides at least a seven-color change, with reduced consumption of manufacturing materials and convenient installation. The light beads are connected in series, and each light bead includes a light bead controller and a plurality of light-emitting elements (e.g., three or more). Control signals are encoded on one of the power supply wires of the light string by a light string controller and are passed from one light bead to the next to effect desired color changes. 
     In one embodiment, an LED light string includes a controller and a plurality of LED colorful light beads. A controller is electrically connected with the LED colorful light beads, and includes control circuitry for controlling the light beads. Additionally, the light beads are connected in series, and the controller is electrically connected with an AC electric supply. 
     In a particular embodiment, each of the LED colorful light beads is a single light bead that is capable of emitting light of different colors (e.g., seven or more). In another particular embodiment, if necessary, a current-limiting resistor is added to the series-connection circuit. 
     Each of the LED colorful light beads can include a first light emitting chip, a second light emitting chip, a third light emitting chip, and a light emitting control integrated circuit (IC) for controlling the light emitting state of the chips. Still more particularly, the first light emitting chip provides red light, the second light emitting chip provides green light, and the third light emitting chip provides blue light. In an even more particular embodiment, the first light emitting chip provides a red light source of 600-700 nm wavelength, the second light emitting chip provides a green light source of 500-600 nm wavelength, and the third light emitting chip provides a blue light source of 400-500 nm. 
     An LED light string having colorful light beads can also include matching (complementary) light string male and female connectors, which can be connected according to the actual needs of users without exceeding the maximum connection length allowed by the controller. 
     In another embodiment, an LED light string having colorful light beads further includes a controller having a power line female connector and a power plug. The power line female connector is inserted into the light string male connector, and the power plug is electrically connected with the AC electric supply. 
     Advantageously, the working mechanism of the LED light string is that within the controller, a control signal of the controller is fused and transmitted together with a power supply signal. That is, a control signal of the controller is transmitted to a first LED colorful light bead through, for example, the LED negative pole of the power supply circuit. After the light-emitting control IC in the first LED colorful light bead receives the signal, the first light-emitting chip, the second light-emitting chip and the third light-emitting chip of the light bead are controlled to emit light by the light-emitting control IC, while the control signal is fused to the output end of the first LED colorful light bead, and then transmitted to a second LED colorful light bead, and so on. Thus, the control signal is transmitted sequentially from one light bead to another, thereby achieving R/G/B full-color change of the whole product. 
     The invention provides the advantage that the LED light string having colorful light beads is designed based on the existing (two power wire) structure of a single-color change light string only by changing the light beads and by adding a connectable controller to achieve, in a particular example, a seven-color change. The invention also provides the advantage that multiple such light strings are connectable according to the actual needs of a user, such that the light string is expandable without exceeding the maximum connection length allowed by the controller. 
     In an exemplary embodiment, a light string includes a first voltage supply line, a second voltage supply line, and a plurality of light beads electrically coupled in series between the first and second voltage supply lines. Additionally, each of the light beads includes a plurality of light-emitting elements and a light bead controller configured to receive a control signal via at least one of the first and second voltage supply lines and, responsive to the control signal, selectively illuminate one or more of the light-emitting elements. 
     In a particular embodiment, each of the light beads includes first and second voltage supply terminals electrically coupled to the light bead controller and a voltage regulator electrically coupled between the first and second voltage supply terminals in parallel with the light bead controller. More specifically, the voltage regulator comprises a Zener diode. 
     In another particular embodiment, the first voltage supply terminal of a first light bead of the plurality is electrically coupled to the first voltage supply line, the second voltage supply terminal of the first light bead is electrically connected to the first voltage supply terminal of a second light bead, the first voltage supply terminal of the last bead is electrically connected to the second voltage supply terminal of a second-to-last light bead of the plurality, and the second voltage supply terminal of the last light bead is electrically coupled to the second voltage supply line. In some more particular embodiments, a current-limiting resistor is electrically coupled in series with the plurality of light beads and/or the light string can include a light string controller operative to assert a first and second drive voltages on the first and second voltage supply lines, respectively, and selectively assert the control signal on one of the first and the second voltage supply lines. 
     In yet another particular embodiment, the light bead controller includes a plurality of illumination programs and the control signal identifies the selected illumination program. The light bead controller is thus configured to illuminate one or more of the plurality of light-emitting elements in accordance with a selected one of the plurality of illumination programs. 
     In still another particular embodiment of the light string, the plurality of light-emitting elements of each of the light beads includes three light-emitting diodes (LEDs), each emitting a single color of light. Accordingly, each light bead is capable of generating any of seven different colors of light. In a more particular example, responsive to the control signal, some of the plurality of light beads display one color of the seven different colors and others of the plurality of light beads display a different color of the seven different colors. In a still more particular example, the plurality of light beads repeatedly switch between the plurality of light beads all displaying a same color of the seven different colors and the plurality of light beads displaying at least two different colors of the seven different colors. 
     In yet another particular embodiment, the light string includes a light string controller operative to assert a first drive voltage on the first voltage supply line, assert a second drive voltage on the second voltage supply line, and selectively assert the control signal on one of the first and the second voltage supply lines. The light string controller can also further include a user interface and control signal generation circuitry. The user interface is operative to receive a signal indicative of a selection of one of the plurality of illumination programs displayable by the plurality of light beads by a user, and the control signal generation circuitry is operative to generate the control signal based on the selected illumination program. The control signal can comprise a series of voltage pulses asserted on the one of the first and the second voltage supply lines. 
     The light string can also be separable and/or expandable. For example, in one embodiment, the light string includes a first connector electrically coupled to a first distal end of at least one of the first voltage supply line and the second voltage supply line and a second connector electrically coupled to a second distal end of at least one of the first voltage supply line and the second voltage supply line. Additionally, the first connector and the second connector are complementary such that multiple pluralities of serially-coupled light beads can be electrically coupled between the first and second voltage supply lines and be responsive to the control signal. In a more particular embodiment, the light string includes a light string controller having a third connector complementary to the first power connector. 
     A light string controller for controlling the illumination of a plurality of series-connected light beads of a light string is also disclosed. In an exemplary embodiment, the light string controller includes a first drive voltage terminal, a second drive voltage terminal, a voltage source configured to assert a first drive voltage on the first drive voltage terminal, and voltage control circuitry configured to selectively assert a second drive voltage and a control signal on the second drive voltage terminal. The first drive voltage terminal is configured to be electrically coupled to a first voltage supply line of a light segment, whereas the second drive voltage terminal is configured to be electrically coupled to a second voltage supply line of the light segment. The light segment includes a plurality of light beads electrically coupled between the first and the second voltage supply lines, and the control signal controls the light output of each of the plurality of light beads. 
     In a particular example, the voltage control circuitry is operative to assert any of a plurality of control signals on the second drive voltage terminal to identify any of a plurality of illumination programs displayable by the plurality of light beads. Optionally, the first and second drive voltage terminals are embodied in a connector configured to removably engage a complementary connector of the light segment. 
     In a more particular embodiment, the light string controller includes a user interface, coupled to the voltage control circuitry, that is operative to receive a selection signal indicative of one of the plurality of illumination programs selected by a user. Accordingly, the control signal asserted on the second drive voltage terminal by the voltage control circuitry identifies the selected illumination program. 
     In another more particular embodiment, at least one of the plurality of illumination programs comprises a multi-color illumination program, where the multi-color illumination program causes the plurality of light beads to repeatedly switch between the plurality of light beads all displaying a same color and the plurality of light beads collectively displaying at least two different colors. 
     In a light string controller, a method for controlling the illumination of a plurality of light beads electrically coupled to the light string controller is also disclosed. An exemplary method includes the steps of asserting a first drive voltage on a first drive voltage terminal of the light string controller, asserting a second drive voltage on a second drive voltage terminal of the light string controller, receiving a program selection signal via a user interface, and asserting a control signal on at least one of the first and second drive voltage terminals to communicate the control signal to the plurality of light beads. The first and second drive voltage terminals are configured to be electrically connected to a first and a second voltage supply lines of a light segment, respectively, where the light segment includes the plurality of light beads electrically coupled between the first and the second voltage supply lines. Additionally, the program selection signal is indicative of an illumination program selected from a plurality of illumination programs, where each of the illumination programs determines a light output of the plurality of light beads, and the asserted control signal is indicative of the selected illumination program. In a particular method, asserting the control signal includes asserting a series of voltage pulses on the second drive voltage terminal. 
     Another particular method further includes a step of asserting the second drive voltage on the second drive voltage terminal following the step of asserting of the control signal. A more particular method further includes the steps of receiving a second program selection signal via the user interface, where the second program selection signal indicates a second illumination program selected from the plurality of illumination programs, and asserting a second control signal indicative of the second illumination program on the second drive voltage terminal. 
     Light beads and their operation are also described in detail. A light bead according to an exemplary embodiment includes a first voltage supply terminal, a second voltage supply terminal, a light bead controller electrically coupled between the first and the second voltage supply terminals, and a plurality of light-emitting elements electrically coupled between the light bead controller and the second voltage supply terminal. The light bead controller is configured to detect a control signal asserted on at least one of the first voltage supply terminal and the second voltage supply terminal and selectively illuminate one or more of the plurality of light-emitting elements to control the light output of the light bead in accordance with the control signal. 
     In a particular embodiment, the light bead further includes a voltage regulator electrically coupled between the first and second voltage supply terminals in parallel with the light bead controller. In a more particular example, the voltage regulator includes a Zener diode, and even more specifically, the light bead controller can include a first input terminal coupled to the first voltage supply terminal and a positive side of the Zener diode, a second input terminal coupled to the second voltage supply terminal and a negative side of the Zener diode, and a plurality of drive terminals. Each of the plurality of light-emitting elements is electrically coupled between one of the plurality of drive terminals and the second voltage supply terminal. 
     In another particular embodiment, the light bead controller is further configured to store a plurality of illumination programs, select one of the plurality of illumination programs based on the control signal, and illuminate one or more of the light emitting elements in accordance with the selected illumination program. 
     In yet another particular embodiment, the plurality of light-emitting elements comprises a first light-emitting diode (LED) configured to emit a first color of light, a second LED configured to emit a second color of light, and a third LED configured to emit a third color of light. Additionally, the first, second, and third colors of light are different, and the light bead is capable of emitting any of seven different colors of light depending on which of the first, the second, and the third LEDs are illuminated simultaneously. 
     In a more particular embodiment, the first LED provides a red light source of 600-700 nm wavelength, the second LED provides a green light source of 500-600 nm wavelength, and the third LED provides a blue light source of 400-500 nm wavelength. 
     In another more particular embodiment, the light bead is configured to be electrically coupled as one of a plurality of the light beads of a light string, the light string comprises a first voltage supply line and a second voltage supply line, and the plurality of the light beads are electrically connected to each other in series between the first voltage supply line and the second voltage supply line. Still more particularly, responsive to the control signal, some of the plurality of light beads are configured to display a first one of the seven different colors and others of the plurality of light beads are configured to display a second one of the seven different colors. Even more particularly still, the plurality of light beads can be further configured to repeatedly switch between the plurality of light beads all displaying a same color of the seven different colors and the plurality of light beads displaying at least two different colors of the seven different colors. 
     In yet another more particular embodiment, the light string includes a light string controller operative to assert a first and second drive voltage on the first and second voltage supply lines and encode the control signal on the second voltage supply line as a series of voltage pulses. 
     A light bead according to another exemplary embodiment includes a first voltage supply terminal, a second voltage supply terminal, a light bead controller electrically coupled between the first and the second voltage supply terminals, a plurality of light emitting elements, means for detecting control signals, and means for transmitting the control signals out of the light bead via the first voltage supply terminal to a next light bead in a series of light beads. In this embodiment, the light bead controller is configured to detect control signals communicated via the second voltage supply terminal and, responsive to the control signals, selectively provide power to one or more of a plurality of power terminals in accordance with the control signal to display an associated one of a plurality of predetermined light outputs. Additionally, each light-emitting element is electrically coupled between an associated one of the plurality of power terminals and the second voltage supply terminal. 
     In a light bead having a plurality of light-emitting elements, a method for controlling the light output of the light bead is also disclosed. The method includes the steps of receiving a first drive voltage asserted on a first voltage supply terminal of the light bead, receiving a second drive voltage asserted on a second voltage supply terminal of the light bead, detecting a control signal asserted on the second voltage supply terminal, selecting one of a plurality of predetermined illumination outputs of said light bead based on said control signal, and powering one or more of the plurality of light-emitting elements to cause the light bead to provide the selected illumination output. 
     According to a particular method, the step of detecting the control signal comprises detecting a series of voltage pulses asserted on the second voltage supply terminal. Still more particularly, a voltage between the first and the second voltage supply terminals is regulated, and the step of detecting the control signal comprises detecting changes in available current between the first and the second voltage supply terminals. 
     In another particular method, each of the plurality of illumination outputs is associated with a different control signal. More particularly, the plurality of illumination outputs can include a plurality of different colors and/or one or more flashing outputs. Still more particularly, one or more of the outputs can define a colored light output of the light bead that forms a component of a multi-colored light output provided by a light string incorporating the light bead and other light beads. For example, according to one method where the light bead includes three light-emitting diodes (LEDs), each emitting light of a different color, the control signal identifies one of at least 32 different selectable illumination outputs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements: 
         FIG. 1  shows side and top structural schematic views of a prior art dual-cup dual-color LED light bulb; 
         FIG. 2  is a structural schematic view of a light string according to an embodiment of the present invention; 
         FIG. 3  is a structural schematic view of a light bead of  FIG. 2  according to an embodiment of the present invention; 
         FIG. 4  is a structural schematic view of the light string controller of  FIG. 2  according to an embodiment of the present invention; 
         FIG. 5  is a block diagram showing the program control unit of  FIG. 4  in greater detail; 
         FIG. 6  is a voltage verses time diagram showing an exemplary multi-pulse control signal generated by the light string controller of  FIG. 4 ; 
         FIGS. 7A-7D  are tables showing exemplary pulse-coding schemes for control signals generated by the light string controller of  FIG. 4 ; 
         FIG. 8  is a block diagram showing the light bead controller of the light bead of  FIG. 3  in greater detail; 
         FIG. 9  is a schematic view showing the light segment of  FIG. 2  in greater detail; 
         FIG. 10  is a circuit diagram of the light segment of  FIG. 2 ; 
         FIG. 11  is a voltage verses time diagram showing sequential control signals asserted by the light string controller of  FIG. 2  on the light segment of  FIG. 2 ; 
         FIG. 12  is a flowchart summarizing a method in a light string controller for controlling the illumination of a plurality of light beads; and 
         FIG. 13  is a flowchart summarizing a method, in a light bead, for controlling the light output of a light bead having a plurality of light emitting elements. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention overcomes the problems associated with the prior art by providing a light string having a plurality of colorful light beads, where each of the light beads is capable of at least a seven-color change. The light beads are controlled using encoded control signals asserted on one of the power supply wires of the light string and are passed from one light bead to the next to effect the desired color changes. In the following description, numerous specific details are set forth (e.g., particular voltages, particular specifications of components, particular encoding techniques, etc.) in order to provide a thorough understanding of the invention. Those skilled in the art will recognize, however, that the invention may be practiced apart from these specific details. In other instances, details of well-known low-voltage lighting components (e.g., light diffusers, etc.) and manufacturing practices (e.g., light string assembly) have been omitted, so as not to unnecessarily obscure the present invention. 
       FIG. 2  is a structural schematic view of a light string  200  having colorful light beads according to one embodiment of the invention. Light string  200  includes a light string controller  202  and a light bead segment  204 . Light bead segment  204  includes a plurality of light beads  206 ( 1 - n ) connected in series between a first (positive) voltage supply line  208  and a second (negative) voltage supply line  210 . Current flows from first voltage supply line  208  to second voltage supply line  210  via the serially-connected light beads  206 ( 1 - n ) and, in some embodiments, through a current limiting resistor  212  included in the series-connected circuit with the light beads  206 ( 1 - n ). While light beads  206 ( 1 - n ) are shown only representationally in  FIG. 2 , additional structure is described in  FIG. 3 . 
     Light segment  204  also includes a first connector  214  (e.g., a male connector, etc.) and a second connector  216  (e.g., a female connector, etc.). First connector  214  is electrically connected to first and second voltage supply lines  208  and  210  at a first distal end of light segment  204 , whereas second connector  216  is electrically connected to first and second voltage supply lines  208  and  210  at a second distal end of light segment  204 . Connectors  214  and  216  are complementary, such that the male connector  214  of a second light segment  204 ( 2 ) (not shown) can be engaged with the female connector  216  of light segment  204  to lengthen the light string  200 . Thus, multiple light segments  204  can be electrically connected together according to the actual needs of a user, without exceeding the maximum connection length permitted by light string controller  202 . The maximum number of connectable light segments  204  will vary depending on the maximum current rating of the controller  202 , the number of beads  206 ( 1 - n ) in each light segment  204 , etc. 
     Light string controller  202  also includes a connector  218 , which provides a removable connection to first connector  214  of light segment  204 . When connected with light segment  204 , connector  218  enables driving voltages and control signals from light string controller  202  to be asserted on respective voltage supply lines  208  and  210  and transmitted to light beads  206 ( 1 - n ). Light string controller  202  also receives power via a power plug  220 , which connects controller  202  with an AC electric supply (e.g., a wall outlet), thereby providing 120V AC source power for light string  200 . A circuit is completed via the light string controller  202 , first voltage supply line  208 , current-limiting resistor  212 , the series-connected light beads  206 ( 1 - n ), second voltage supply line  210 , and connectors  218  and  214  therebetween. When power plug  220  is plugged into the AC supply, light string  200  is powered by light string controller  202 , and the light beads  206 ( 1 - n ) can be illuminated to generate any of a plurality of desired light outputs as will be described below. 
     It should also be noted that connectors  214 ,  216 ,  218  enable the components of light string  200  to be separated and light string  200  expanded. However, in other embodiments, components of light string  200 , including multiple pluralities of light beads  206 ( 1 - n ), can be made as an inseparable structure. 
       FIG. 3  is a structural schematic view showing one of light beads  206 ( 1 - n ) in greater detail. Light bead  206  includes a first voltage supply terminal  302 , a second voltage supply terminal  304 , a light bead controller  306 , a voltage regulator  308 , and a plurality of light-emitting elements. The plurality of light-emitting elements includes a first light-emitting element  310 , a second light-emitting element  312 , and a third light-emitting element  314 . Light bead  206  also includes one or more (two shown) support members  316 , which support and optionally facilitate electrical connections between the elements of light bead  206 . 
     First voltage supply terminal  302  is the positive voltage node (labeled “X”) of light bead  206 , whereas second voltage supply terminal  304  is the negative voltage node (labeled “Y”). As will be explained further below, transmission of control signals from light string controller  202  ( FIG. 2 ) are back-ordered through the plurality of light beads  206 ( 1 - n ), being received at each light bead  206  via second voltage supply terminal  304  and provided to the next light bead  206  in the series via first voltage supply terminal  302 . Accordingly, light bead  206  includes a means (e.g., a soldered connection, pin, connector, etc.) for electrically connecting each of voltage supply terminals  302  and  304  to an adjacent light bead  206 , current limiting resistor  212 , or voltage supply line. 
     Light bead controller  306  includes a first input terminal  318 , a second input terminal  320 , and a plurality (three in this embodiment) of drive terminals  322 ,  324 , and  326 . First input terminal  318  is electrically coupled to first voltage supply terminal  302 , whereas second input terminal  320  is electrically coupled to second voltage supply terminal  304  at node Y. Each of light emitting elements  310 ,  312 , and  314  is electrically connected between a respective one of drive terminals  322 ,  324 , and  326 , and second voltage supply terminal  304  at node Y. Here, because light bead controller  306  is operative to independently power each of light emitting elements  310 ,  312 , and  314 , the number of drive terminals is at least equal to the number of light-emitting elements. 
     Voltage regulator  308  regulates the voltage between first and second voltage supply terminals  302  and  304 . Here, voltage regulator  308  comprises a Zener diode coupled between first and second voltage supply terminals  302  and  304  in reverse bias. Accordingly, Zener diode  308  maintains the voltage between first and second voltage supply terminals  302  and  304  at its Zener voltage, as long as the voltage between terminals  302  and  304  is greater than or equal to its Zener voltage. In a particular embodiment, Zener diode  308  has a Zener voltage of 3.3 Volts and a power rating of 0.25 Watts. 
     Light bead controller  306  is electrically coupled to first and second voltage supply terminals  302  and  304 , in parallel with Zener diode  308 , and is configured to detect control signals received via second voltage supply terminal  304 . In a particular embodiment, a control signal is encoded as a series of voltage pulses, which identifies one of a plurality of illumination programs stored by light bead controller  306 . The control signal is received on voltage supply terminal  304  and provided to light bead controller  306  at second input terminal  320 . The control signal is also transmitted to Node X and first voltage supply terminal  302  via Zener diode  308 . Responsive to a control signal being received, light bead controller  306  identifies an illumination program associated with the control signal from a plurality of available illumination programs. After assertion of the control signal, light bead controller  306  selectively powers one or more of light emitting elements  310 ,  312 , and  314  according to the identified illumination program via one or more of drive terminals  322 ,  324 , and  326 , such that light bead  206  generates the desired illumination output (light color and/or effect). 
     Light emitting elements  310 ,  312 , and  314  enable light bead  206  to produce multiple colors of light. First light-emitting element  310  comprises a first light emitting diode (LED) that emits light of a first color (e.g., red), second light-emitting element  312  comprises a second LED that emits light of a second color (e.g., green), and third light-emitting element  314  comprises a third LED that emits light of a third color (e.g., blue). More specifically, LED  310  provides a red light source of 600-700 nm wavelength, LED  312  provides a green light source of 500-600 nm wavelength, and LED  314  provides a blue light source of 400-500 nm wavelength. Because each of LEDs  310 ,  312 , and  314  generates a different color of light and can be illuminated by controller  306  independently, light bead  206  can selectively generate any of seven different colors. Those colors are red, green, blue, yellow (red and green), magenta (red and blue), cyan (green and blue), and white (red, green, and blue). Additionally, light bead controller  306  can cause the light bead  206  to flash, change intensity, switch colors in alternation, turn off, etc. according to any of its predefined illumination programs. LEDs  310 ,  312 , and  314  can be embodied, for example, in respective silicon chips. LEDs  310 ,  312 , and  314  can also be embodied as standard LEDs, rather than the surface mount (SMD) variety, which lowers cost. 
       FIG. 4  is a structural schematic view of light string controller  202  ( FIG. 2 ) according to an embodiment of the present invention. Light string controller  202  includes a housing  402 , a rectifier filter  404 , step-down circuitry  406 , a program control unit  408 , and a voltage assertion unit  410 . Rectifier filter  404  receives 120 volt AC power when power plug  220  is plugged into a wall outlet (not shown), and rectifies and conditions the AC power into filtered DC power. During operation, rectifier filter  404  provides a first drive voltage (e.g., 170V DC) to a first drive voltage terminal  412  of connector  218 , via a first drive voltage line  414 , and also to step-down circuitry  406  via line  416 . Rectifier filter  404  also provides a second voltage (e.g., 0V DC) to step down circuitry  406 , program control unit  408 , and voltage assertion unit  410  via line  418 . 
     Step down circuitry  406  reduces the high voltage from rectifier filter  404  to a lower voltage (e.g., 5V DC), and provides the stepped-down voltage to program control unit  408  and to voltage assertion unit  410  via line  420 . Program control unit  408  comprises integrated circuitry and causes control signals for light beads  206 ( 1 - n ) to be output by light string controller  202 . More particularly, program control unit  408  causes voltage assertion unit  410  to selectively assert a series of voltage pulses on a second drive voltage line  422  and, thus, on a second drive voltage terminal  424  of connector  218  as a control signal. When connected with light segment  204 , the control signal is communicated to the series-connected light beads  206 ( 1 - n ) via second voltage supply line  210 . 
     Light string controller  202  also includes a user interface, which facilitates user control over the light output of light segment  204 . In this example, the user interface comprises a wireless interface  426 , in communication with program control unit  408 , and a remote control  428 . Remote control  428  communicates (e.g., by infrared (IR), radio, Bluetooth, etc.) with wireless interface  426  of program control unit  408  using a complementary wireless interface  430 . Remote control unit  428  also includes one or more program selection input(s)  432 , which enables a user to select a desired operation for light segment(s)  204 . Program selection input(s)  432  can, for example, comprise button(s), knob(s), switch(es), a smartphone application, etc. In the case of a smartphone application, the application can communicate with program control unit  408  via Bluetooth and/or an IR port of the smartphone. 
     Program selection inputs  432  can be incorporated into controller  202  as an alternative, or in addition, to remote control  428 . In one such example, light string controller  202  includes a simplified user input, such as a single selector  440  (e.g., a rotatable knob, etc.) in communication with program control unit  408 . Knob  440  is rotated by the user to different angular positions to select a desired light output of light segment  204 . In one example, knob  440  is rotated by the user to select from the following three light outputs: (1) steady white light, (2) steady multi-color light (different light beads  206 ( 1 - n ) in the light segment produce different colors simultaneously), and (3) color changing from white to multi-color output. 
     When a user selects a desired operation/output for light segment  204 , program control unit  408  receives the program selection signal and identifies at least one control signal to provide to light beads  206 ( 1 - n ) to implement the user&#39;s program selection. Then, program control unit  408  causes voltage assertion unit  410  to assert the identified control signal on second drive voltage terminal  424 . More particularly, program control unit  408  controls voltage assertion unit  410  via one or more line(s)  434  to selectively assert each identified control signal on voltage terminal  424  as an encoded series of voltage pulses having predefined signal characteristics (e.g., frequency, time interval, pulse weight, etc.). 
     Responsive to control input from program control unit  408 , voltage assertion unit  410  asserts either a steady-state voltage or a pulse of a control signal on second drive voltage line  422  and second drive terminal  424 . In a particular example, the control input comprises a series of activation pulses output by program control unit  408 , which corresponds to the control signal that needs to be output from light string controller  202 . When program control unit  408  is not asserting an activation pulse on control line  434 , voltage assertion unit  410  asserts the second drive voltage (e.g., 0V, etc.) on second drive voltage line  422 . Conversely, when program control unit  408  asserts an activation pulse on control line  434 , voltage assertion unit  410  causes a corresponding pulse to be asserted on second drive voltage line  422  at a voltage (e.g., 5V DC) that is different than the steady state drive voltage. Thus, an encoded multi-pulse control signal, is communicated to the light beads  206 ( 1 - n ) via terminal  424 . In a particular embodiment, voltage assertion unit  410  comprises a silicon controlled rectifier (SCR). 
     In summary, with reference to  FIGS. 2-4 , the working mechanism of the embodiment is that, within the light string controller  202 , a control signal of the controller  202  is fused and transmitted together with a power supply signal. That is, a control signal of light string controller  202  is transmitted to a first light bead  206 ( n ) via the negative pole of the power supply circuit, which here includes second drive terminal  424  of controller  202  and second voltage supply line  210  of light segment  204 . After light bead controller  306  in light bead  206 ( n ) receives the control signal, a first light-emitting element  310 , a second light-emitting element  312 , and a third light-emitting element  314  of the light bead  206 ( n ) are controlled by light bead controller  306  to emit light according to the illumination program identified by the control signal. Additionally, the control signal is further fused to the voltage supply terminal  302  of the light bead  206 ( n ), such that it is transmitted to a next light bead  206 ( n− 1), and so on. Thus, the control signal is transmitted from one light bead to another, thereby achieving R/G/B full-color and/or flicker change of the whole product in accordance with the control signal. 
     The invention provides the advantage that the light string  200  is simple in construction, utilizing only two voltage supply lines  208  and  210  and including inexpensive light beads having controllable, variable color illumination outputs. A connectable controller encodes control signals on one of the voltage supply lines to control the light output of the light beads. The light beads can be operated according to any of a plurality of predefined illumination programs, including seven different colors, multi-color, flicker, gradation/dimming, etc. The invention also provides the advantage that multiple light segments are connectable according to the actual needs of a user, such that the light string is expandable. 
       FIG. 5  is a block diagram showing program control unit  408  in greater detail to include a control signal selection module  502  in addition to wireless interface  426 . When wireless interface  426  receives a program selection signal indicative of a light output selected by a user, it provides the program selection signal to control signal output module  502 . Control signal output module  502  then provides an output (e.g., a series of activation pulses) corresponding to a desired control signal indicative of the selected program to voltage assertion unit  410 . In a particular embodiment, control signal output module  502  stores a plurality of unique control signal definitions corresponding to different illumination programs stored by light beads  206 ( 1 - n ) and to different program selection signals provided by remote control  428 . 
     In one embodiment, the control signal output by light string controller  202  on voltage supply line  210  is encoded based on frequency of the pulse signals.  FIG. 6  is a Voltage vs. Time diagram illustrating an exemplary multi-pulse control signal  600  provided to light segment  204 . Control signal  600  is asserted within a pulse window  602  between times t 1  and t 2 , which in this example is 25 milliseconds. Control signal  600  is encoded using eight pulses  604  of constant duration, where the eight pulses  604  are separated into groups. The time interval between consecutive pulses  604  of the same group is short (corresponding to a higher frequency), whereas the time interval between the last and first pulses of consecutive groups is relatively longer (corresponding to a lower frequency). 
     As the example in  FIG. 6  shows, control signal  600  includes a first group  606  of four pulses  604  followed by a second group  608  of four pulses  604 , which represent an illumination program code of “4-4”. The time between pulses  604  in each of groups  606  and  608  is short, whereas the time between the last and first pulses of consecutive groups  606  and  608  is relatively longer. Accordingly, light bead controller  306  can detect this relatively long time period to distinguish groups  606  and  608 . Light bead controller  306  can also detect the number of pulses  604  within each group based on their more frequent occurrence. As another example, an illumination program code of 5-2-1 can be encoded as three groups of pulses, with the first group containing five pulses  604 , the second group containing two pulses  604 , and the third group containing one pulse  604 . The first-and-second and the second-and-third groups would also be separated by longer time intervals than the pulses within the individual groups. 
     It should be noted that the control signal encoding scheme shown in  FIG. 6  is exemplary and other coding schemes can be used. For example, light string controller  202  can use a coding scheme that encodes different illumination program codes as a set of pulses of differing weights (durations). Accordingly, pulse  600  would be encoded as two pulses of the same duration (i.e., four time intervals each). Similarly, program code 5-2-1 would be encoded as three pulses having durations of five time intervals, two time intervals, and one time interval, respectively, for a total pulse weight of eight time intervals. Thus, various pulse-coding schemes can be used. 
       FIGS. 7A-7D  are tables  700 A- 700 D associating exemplary program codes for multi-pulse control signals and illumination programs/outputs produced by light beads  206 ( 1 - n ) in response to receiving the control signals. Each of tables  700 A- 700 D includes a first column  702 , showing illumination program codes (identifiers) for different control signals, and a second column  704  showing illumination programs. Each row of tables  700 A- 700 D associates a control signal&#39;s program code with an illumination program/output for light beads  206 ( 1 - n ). 
     Table  700 A shows program codes in column  702  associated with solid color outputs of light beads  206 ( 1 - n ) in column  704 . Note that the program code of 4-4 (two groups of four pulses) will cause light segment  204  to generate a multi-color output, which causes different pluralities of light beads  206 ( 1 - n ) in light segment  204  to illuminate in different colors. Responsive to a multi-color code, a first plurality of light beads  206  will illuminate with a first color in column  704 , whereas a second plurality of light beads  206  will illuminate with a second (different) color in column  704 , and so on. Given that there are seven colors, up to seven pluralities of light beads  206  having different colors can be defined in multi-color mode. 
     As some additional examples, table  700 A shows that the program code 5-2-1 causes light beads  206 ( 1 - n ) to display purple (e.g., by illuminating red LED  310  and blue LED  314 ). A program code of 4-1-1-2, which is comprised of four groups having, respectively, four pulses, one pulse, one pulse, and two pulses, will cause light beads  206 ( 1 - n ) to turn off. A pulse code of 5-1-1-1 will cause the light beads  206 ( 1 - n ) to generate white light. Thus, by asserting the program codes in table  700 A, light beads  206 ( 1 - n ) can be turned off or turned on to produce any of red, green, blue, yellow, purple, cyan, white, and multi-color as indicated. 
     Tables  700 B- 700 D show other associated program codes and illumination outputs of light beads  206 ( 1 - n ). Table  700 B shows program codes associated with gradient/dimming outputs of light beads  206 ( 1 - n ) for each color and multi-color output. Table  700 C shows program codes associated with “color-plus-white” flashing outputs of light beads  206 ( 1 - n ), where white and the color (or multi-color) flash according to some pattern (e.g., in alternation). If “white” is selected (code 1-2-2-1-1-1), then light beads  206 ( 1 - n ) can flash in a predetermined pattern. Table  700 D shows pulse codes associated with light beads  206 ( 1 - n ) flashing in one color or in multi-color. If “white” is selected, then light beads  206 ( 1 - n ) flash in a predetermined pattern, optionally different than that associated with Table  700 C. 
     It should also be noted that the program codes associated with tables  700 A- 700 D are coded by type of light output. For example, the first group of pulses in each of the codes for solid colors (and “Off”) in column  702  of table  700 A has four pulses or more. In table  700 B for gradient/dimming output, the first group of pulses of each program code includes three pulses. In table  700 C, each of the “color-plus-white” flashing codes begins with a first group of one pulse followed by a second group of two pulses. Finally, in table  700 D, each of the single color flashing codes begins with three consecutive groups of one pulse each. 
     Returning briefly to  FIG. 4 , where light string controller  202  includes knob  440  ( FIG. 4 ), knob  440  can be rotated by the user to select a particular type of desired light output (e.g., solid, gradient, color+white flashing, color flashing, etc.). Once selected, program control unit  408  causes control signals to be generated by light string controller  202  within the selected type (e.g., within one of tables  700 A- 700 D) so that light segment  204  is illuminated accordingly. 
     As mentioned previously, knob  440  can also select between predefined lighting routines, for example, (1) steady white light, (2) steady multi-color output, and (3) color changing from white to multi-color output. In such an embodiment, program control unit  408  causes control signals to be generated that correspond to the selected predefined lighting routine. If the user selects predefined lighting routine (1), light string controller  202  outputs a control signal corresponding to program code 5-1-1-1 to cause all light beads  206 ( 1 - n ) to turn white. Similarly, if the user selects predefined lighting routine (2), light string controller  202  outputs a control signal  600  corresponding to program code 4-4 that causes all light beads  206 ( 1 - n ) to turn multi-color. If the user selects predefined lighting routine (3), light string controller  202  outputs a control signal for program code 1-2-1-4, which causes the light beads  206 ( 1 - n ) to display white, then multi-color, then white, and so on. 
     In other instances, program control unit  408  of light string controller  202  can include programming to generate illumination routines using the program codes  702 . For example, program control unit  408  can store a routine that causes program codes  7 - 1  and  6 - 2  to be output to light beads  206 ( 1 - n ) repeatedly in alternation such that light beads  206 ( 1 - n ) switch from green to red, to green, to red, and so on. As another example, program control unit  408  can include a routine that loops through all colors in gradient mode by causing the program codes in column  702  of table  700 B to be provided to light segment  204  in some order, such as 3-4-1, 3-3-2, 3-2-3, etc. This generates red light with dimming, green light with dimming, blue light with dimming, etc. As another example, program control unit  408  can send a random series of program codes to light beads  206 ( 1 - n ) to illuminate light segment  204  at random. Such routines can be stored in program control unit  408  and can be user selectable via program selection input  432 , such that they and the illumination programs stored by light beads  206 ( 1 - n ) can be used in conjunction. 
       FIG. 8  is a block diagram showing light bead controller  306  in greater detail. Light bead controller  306  includes a control signal detection module  802 , an illumination program selection module  804 , and an LED driver  806 . In the present embodiment, light bead controller  306  is an integrated circuit chip having modules  802  and  804  and driver  806  formed therein. 
     The modules of light bead controller  306  provide the following functions. Control signal detection module  802  detects control signals communicated via second voltage supply terminal  304 , resolves the program code thereof, and provides the program code to illumination program selection module  804 . In a particular embodiment, control signal detection module  802  detects changes in the available current flowing through light bead controller  306  responsive to each pulse  604  of the control signal to determine its program code. In some embodiments, control signal detection module  802  can be triggered into action by changes in available current caused by receipt of the first pulse of a control signal. 
     Illumination program selection module  804  stores a plurality of predefined illumination programs, such as the illumination programs in columns  704  of tables  700 A- 700 D, in association with a plurality of program codes, such as those in columns  702  of tables  700 A- 700 D, where each of the illumination programs causes a different light output of light bead  206 . Illumination program selection module  804  receives a program code from control signal detection module  802 , associates the program code with one of the plurality of illumination programs stored therein, and outputs LED control signals indicative of the associated illumination program to LED driver  806 . LED driver  806  receives the LED control signals and, in response, provides power to one or more of drive terminals  322 ,  324 , and  326  to illuminate one or more of LEDs  310 ,  312 , and  314 , respectively, in accordance with the illumination program. Thus, light bead  206  illuminates according to the selected illumination program until another control signal is received. 
     Multi-color output of light strand  204  can be accomplished in the programming light bead controller  306  in several ways. In one embodiment, responsive to receiving a program code that requires multi-color output, illumination program selection module  804  can select one of the colors (e.g., red, green, blue, yellow, purple, cyan, and (optionally) white) at random, and then controls LED driver  806  to cause the associated light bead  206  to generate the randomly selected color. Thus, for a light strand having 50 light beads  206 ( 1 - 50 ) each selecting at random from seven available colors (including white), there will be about seven light beads  206  displaying each color. Another option is to program different sets of light beads  206 ( 1 - n ) to display different colors in multi-color mode. For example, a first group of light beads  206 ( 1 - n ) can be programmed to display a first color (e.g., red), a second group a second color (green), a third group a third color (blue), etc. The number of programmed groups or number of selectable colors for multi-color mode can also be configured as desired. 
       FIG. 9  is a schematic view of light segment  204  showing the connections between light beads  206 ( 1 - n ) in greater detail.  FIG. 9  shows that the first voltage supply terminal  302  of the first light bead  206 ( 1 ) in the series is electrically coupled to first voltage supply line  208  via current-limiting resister  212 , and the second voltage supply terminal  304  of light bead  206 ( 1 ) is electrically connected to the first voltage supply terminal  302  of the second light bead  206 ( 2 ). The second voltage supply terminal  304  of second light bead  206 ( 2 ) would similarly be connected to the first voltage supply terminal  302  of a third light bead  206 ( 3 ) (not shown in  FIG. 9 ) and so on. Near the end of the series, a second-to-last light bead  206 ( n −1) has its first voltage supply terminal  302  electrically connected to the second voltage supply terminal  304  of a third-to-last light bead  206 ( n −2) (not shown) and has its second voltage supply terminal  304  connected to the first voltage supply terminal  302  of last light bead  206 ( n ). The second voltage supply terminal of  304  of last light bead  206 ( n ) is connected to second voltage supply line  210 . 
     In the present embodiment, first and second voltage supply lines  208  and  210  are insulated conductive wires having light beads  206 ( 1 - n ) connected in series therebetween, for example, as discrete modules. Thus, light segment  204  has a traditional string-like appearance. In other embodiments, light segment  204  can be in a light belt form, for example, including an elongated flexible circuit substrate having the elements of light beads  206 ( 1 - n ) mounted thereon at regular intervals and powered by first and second conductive traces  208  and  210  formed on the circuit substrate. Light segment  204  can also include lenses over each individual light bead and/or a tubular sheath surrounding the light segment  204 , etc. 
       FIG. 10  is a circuit diagram showing a light segment  204  having fifty light beads  206 ( 1 - 50 ) connected in series along with current-limiting resistor  212  between first voltage supply line  208  (LED+) and second voltage supply line  210  (LED−). At steady state, light string controller  202  asserts 170V DC and 0V DC on first and second voltage supply lines  208  and  210 , respectively. During steady state, the Zener diode  308  in each light bead  206  acts as a voltage regulator, maintaining the voltage across the first and second voltage supply terminals  302  and  304  of that light bead  206  at 3.3V. The combined voltage across the fifty light beads  206 ( 1 - 50 ) is, therefore, 165V DC (i.e., 3.3V×50). The remaining voltage is accounted for across current-limiting resistor  212 , and the available current to each of light beads  206 ( 1 - 50 ) is maximum. 
       FIG. 10  also shows that light string controller  202  has asserted a multi-pulse control signal  600  on negative voltage supply line  210 , where each pulse  604  is asserted at 5V DC. When a pulse is asserted on node  304  of light bead  206 ( 50 ), the pulse is quickly communicated up the chain of Zener diodes  308  in light beads  206 ( 50 - 1 ), and the voltage between first and second voltage supply lines  208  and  210  falls to 165V DC. This voltage is sufficient for the chain of Zener diodes  308  to continue regulating voltage for their respective light beads  206 ( 1 - 50 ), but causes the voltage across, and the current through, the current-limiting resistor  212  to be reduced to a minimum. As a result, the available current to the light beads  206 ( 1 - 50 ) is also significantly reduced. 
     Thus, each control pulse asserted on second voltage supply line  210  limits the available current through the chain of light beads  206 ( 1 - n ) due to current-limiting resistor  212 . Because the reduction in available current coincides with the assertion of each pulse  604  (or lack thereof), the light bead controller  306  of each light bead  206 ( 1 - 50 ) is able to detect each pulse  604  and the associated times between consecutive pulses  604  of the control signal  600 . Accordingly, light bead controller  306  is able to decipher a program code of the control signal  600 , associate the program code with an illumination program stored therein, and then execute the illumination program following assertion of the control signal  600  (e.g., after pulse window  602  closes). 
       FIG. 11  is a voltage verses time diagram  1100  showing voltages asserted on first voltage supply line  208  and second voltage supply line  210  by light string controller  202  during operation. DC voltage is shown on the vertical axis, and time is shown on the horizontal axis. Light string controller  202  asserts a constant drive voltage (e.g., 170V DC) on first voltage supply line  208  during operation. However, both a constant voltage (e.g., 0V DC) and multi-pulse control signals (e.g., with 5V DC pulses) are selectively asserted on second voltage supply line  210 . 
     From time t 0  to time t 1 , the light beads  206 ( 1 - n ) operate in steady state according to an initial illumination program. The initial illumination program can, for example, correspond to a default color that is displayed on initial power to light string  200 . Then, between times t 1  and t 2 , light string controller  202  asserts a first control signal  1102  on second voltage supply line  210 , where first control signal  1102  corresponds to a new illumination program. In this embodiment, first control signal  1102  is a multi-pulse control signal  600  ( FIG. 6 ), but is shown representationally as an elongated hexagon to indicate that other pulse-coding schemes can be used. The light bead controller  306  of each light bead  206 ( 1 - n ) receives the first control signal  1102 , decodes the first control signal  1102 , and loads the associated first new illumination program. At time t 2 , light string controller  202  again asserts a stable voltage on second voltage supply terminal  210  such that the light beads  206 ( 1 - n ) are illuminated according to the first new illumination program until time t 3 . 
     At time t 3 , light string controller  202  asserts a second control signal  1104  on second voltage supply line  210 , where second control signal  1104  corresponds to a second new illumination program. The light bead controller  306  of each light bead  206 ( 1 - n ) receives the second control signal  1104 , decodes it, and loads the associated second new illumination program stored therein. At time t 4 , light string controller  202  again asserts the steady-state voltage on second voltage supply terminal  210  such that the light beads  206 ( 1 - n ) are illuminated according to the second new illumination program. 
     Methods of the present invention will now be described with reference to  FIGS. 12-13 . For the sake of clear explanation, these methods might be described with reference to particular elements of the previously-described embodiments. However, it should be noted that other elements, whether explicitly described herein or created in view of the present disclosure, could be substituted for those cited without departing from the scope of the present invention. Therefore, it should be understood that the methods of the present invention are not limited to any particular elements that perform any particular functions. Furthermore, some steps of the methods presented herein need not necessarily occur in the order shown. For example, in some cases two or more method steps may occur simultaneously. These and other variations of the methods disclosed herein will be readily apparent, especially in view of the description of the present invention provided previously herein, and are considered to be within the full scope of the invention. 
       FIG. 12  is a flowchart summarizing a method  1200  in a light string controller for controlling the illumination of light beads electrically coupled in series between first and second drive voltage terminals of the controller. In a first step  1202 , a first drive voltage is asserted on the first drive voltage terminal of the controller, and in a second step  1204 , a second drive voltage is asserted on the second drive voltage terminal. In a third step  1206 , a program selection signal is received via a user interface of the light string controller. The program selection signal is indicative of an illumination program selected from a plurality of illumination programs by the user, where each of said illumination programs determines a light output of the plurality of light beads. In a fourth step  1208 , a control signal indicative of the selected illumination program is asserted on at least one of the first and second drive voltage terminals to be communicated to each of the plurality of light beads. 
       FIG. 13  is a flowchart summarizing a method  1300  for controlling the light output of a light bead having a plurality of light emitting elements. In a first step  1302 , a first drive voltage is received on a first voltage supply terminal, and in a second step  1304 , a second drive voltage is received on a second voltage supply terminal. In a third step  1306 , a control signal asserted on the second voltage supply terminal is detected, and in a fourth step  1308 , one of a plurality of predetermined illumination outputs of the light bead is selected based on the control signal. In a fifth step  1310 , one or more of the plurality of light-emitting elements of the light bead is powered to cause the light bead to provide the selected illumination output. 
     The description of particular embodiments of the present invention is now complete. Many of the described features may be substituted, altered or omitted without departing from the scope of the invention. For example, alternative pulse coding schemes (e.g., pulse-width modulated pulses, etc.) may be substituted for the pulse coding disclosed. As another example, different driving voltages, Zener diodes having different specifications, and/or numbers of light beads in a chain can be employed. These and other deviations from the particular embodiments shown will be apparent to those skilled in the art, particularly in view of the foregoing disclosure.