Abstract:
An LED control system using a modulated signal includes a computer, a data storage unit, an AC power, a power conversion circuit, a control circuit, and an LED lamp string. The AC power is converted into a DC power by the power conversion circuit to supply a DC voltage to the control circuit and the LED lamp string. A computer control data is sent to the control circuit through the data storage unit by a user using the computer. The computer control data is modulated to a modulated signal by the control circuit. The modulated signal is sent to the LED lamp string with the same transmission line sending the DC voltage. The light of the LED lamp string is changed according to the modulated signal. The cost is reduced because the DC voltage and the modulated signal are sent in the same transmission line.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an LED control system, and more particularly to an LED control system using a modulated signal. 
     2. Description of Prior Art 
     Nowadays, the connection way of the LED lamp string modules is separated into two types: serial-type connection and parallel-type connection. The LED lamp string modules are widely used for decoration of trees, scenery designing, signboard, external walls of the building, and so on, because of small size, long life, low power, rapid response, and strong shake-proof property for the LEDs. 
     The prior art LED lamp string modules are commonly employed to be connected in series. Also, the amount of the LED lamp string modules is determined according to volume of the decorated objects. In addition, all of the LED lamp string modules are controlled by the same controller which initially controls the first LED lamp string module. Although the LED lamp string modules are easily connected together, the remaining LED lamp string modules behind the abnormal LED lamp string module can not be lighted even only one of the LED lamp string modules is abnormal. That is because the control signal can not be sent to drive all of the remaining LED lamp string modules. 
     In addition, in operation the parallel-type LED lamp string modules are connected to the controller in parallel. Accordingly, each one of the LED lamp string modules is controlled by the controller through a control line and an address line, respectively. For example, ten control lines and ten address lines need to be used when ten LED lamp string modules are employed to be connected in parallel. Also, the remaining LED lamp string modules can still be normally controlled when one of the LED lamp string modules is abnormal. However, the amount of the control lines and the address lines increase proportionally. Therefore, complexity and costs of the equipment also increase when the amount of the LED lamp string modules increases. 
     Now matter the connection way of the LED lamp string modules is serial-type or parallel-type, many power transmission lines and signal transmission lines need to be used to control the color and intensity of the LED lamp string modules. Accordingly, cost down can be achieved only if the amount of the power transmission lines or the signal transmission lines can be reduced. 
     SUMMARY OF THE INVENTION 
     Accordingly, an LED control system using a modulated signal is provided to reduce the use of the transmission lines and save the costs. 
     In order to achieve the objectives mentioned above, the LED control system using a modulated signal is provided to store a computer control data in a data storage unit, and a data signal outputted from the data storage unit is used to control the color and intensity of the LEDs. The LED control system includes a power conversion, a control circuit, and a plurality of LED emission circuits. The power conversion circuit is provided to convert an AC power into a DC power. The control circuit is electrically connected to the power conversion circuit to receive the DC power outputted from the power conversion circuit and the data signal outputted from the data storage unit, and to modulate the data signal to a modulated signal. The LED emission circuits are electrically connected in series to the control circuit through a transmission line to receive the DC power outputted from the control circuit and the modulated signal to vary the color and intensity of the LEDs. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following description, drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
       The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes an exemplary embodiment of the invention, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of an LED control system using a modulated signal according to the present invention; 
         FIG. 2  is an internal block diagram of a control circuit and an LED lamp string; 
         FIG. 3  is an internal block diagram of an LED emission circuit; 
         FIG. 4  is a timing sequence diagram of communicating a modulated signal between the LED emission circuits; 
         FIG. 5  is a schematic view of a modulated signal (upper part) and a data signal (lower part); 
         FIG. 6A  is a schematic view of an embodiment of a modulation unit; 
         FIG. 6B  is a schematic view of an embodiment of a demodulation unit; 
         FIG. 7  is a block diagram of another embodiment of the LED control system using a modulated signal; and 
         FIG. 8  is another internal block diagram of the LED emission circuit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In cooperation with attached drawings, the technical contents and detailed description of the present invention are described thereinafter according to a preferable embodiment, being not used to limit its executing scope. Any equivalent variation and modification made according to appended claims is all covered by the claims claimed by the present invention. 
     Reference will now be made to the drawing figures to describe the present invention in detail.  FIG. 1  is a block diagram of an LED control system using a modulated signal according to the present invention. The LED control system includes a computer  2 , a data storage unit  4 , an AC power  6 , a power conversion circuit  8 , a control circuit  10 , and an LED lamp string  14 . The computer  2  is electrically connected to the data storage unit  4 . The AC power  6  is electrically connected to the power conversion circuit  8 . The control circuit  10  is electrically connected to the data storage unit  4 , the power conversion circuit  8 , and the LED lamp string  14 , respectively. The operational procedure of this embodiment is as follows. First, a computer control data is stored in the data storage unit  4  by the computer  2 , and the computer control data is sent to the control circuit  10  through the data storage unit  4  to control the color and intensity of the LED lamp string  14 . A data signal is sent to the control circuit  10  by the data storage unit  4 . Also, the control circuit  10  modulates the data signal into a modulated signal, and the modulated signal is advantageous for signal transmission. The power conversion circuit  8  converts the AC power  6  (such as a 110-volt utility power) into a DC power (such as a 110-volt DC power) after the power conversion circuit  8  receives the AC power  6 . Also, the DC power is provided to drive the control circuit  10  and the LED lamp string  14  with the same transmission line that is used to send the modulated signal to the LED lamp string  14 . 
     Reference is made to  FIG. 2  which is an internal block diagram of a control circuit and an LED lamp string. The control circuit  10  includes a voltage stabilizer unit  102  (such as a Zener diode), a microcontroller unit  104 , and a first modulation unit  106 . The microcontroller unit  104  is electrically connected to the data storage unit  4 , the voltage stabilizer unit  102 , the power conversion circuit  8 , the first modulation unit  106 , and the LED lamp string  14 , respectively. The first modulation unit  106  is electrically connected to the voltage stabilizer unit  102 , the power conversion circuit  8 , the microcontroller unit  104 , and the LED lamp string  14 , respectively. The LED string  14  is composed of a plurality of LED emission circuits  140 _ 1 ,  140 _ 2 , . . . ,  140 _N. (The LED emission circuits  140 _ 1 ,  140 _ 2 , . . . ,  140 N will be collectively represented with numeral  140  hereafter.) The LED emission circuits  140  are electrically connected in series, and one terminal of the first LED emission circuit  140 _ 1  is electrically connected to the voltage stabilizer unit  102 , the microcontroller unit  104 , and the first modulation unit  106 , respectively. 
     The operation relation between the control circuit  10  and the LED lamp string is as follows. The power conversion circuit  8  provides a high DC voltage, such as a 110-volt DC voltage. The voltage stabilizer unit  102  provides a DC voltage to drive the microcontroller unit  104  and the first modulation unit  106 . The microcontroller unit  14  receives the data signal sent from the data storage unit  4 . Afterward, the data signal is sent from the microcontroller unit  14  to the first modulation unit  106  to modulate the data signal to generate the modulated signal. (The detailed description is as follows.) Afterward, the modulated signal is sent to the LED lamp string  14  with the same transmission line that is used to send the DC power to the control circuit  10  and the LED lamp string  14 . The first LED emission circuit  140 _ 1  receives the DC power and the modulated signal sent from the control circuit  10  to light the corresponding LEDs. Afterward, the DC power and the modulated signal are sent to the next LED emission circuit, namely the second LED emission circuit  140 _ 2 . 
     Reference is made to  FIG. 3  which is an internal block diagram of an LED emission circuit. The LED emission circuit  140  includes a signal acquisition unit C (such as a capacitor), an amplifier unit  142 , a demodulation unit  14 , a voltage regulator unit  146 , a red light LED  148 R, a green light LED  148 G, a blue light LED  148 B, a first constant current source  150 R, a second constant current source  150 G, a third constant current source  150 B, an output temporary storage unit  152 , a latch unit  153 , a filter unit  154 , a recognition and logic controller unit  156 , a counter and shift register unit  158 , an encoder unit  160 , and a second modulation unit  162 . For the first LED emission circuit  140 _ 1 , a VDD terminal is where that the DC power and the modulated signal are sent from the control circuit  10 . For the second LED emission circuit  140 _ 2 , the VDD terminal is where that the DC power and the modulated signal are sent from the first LED emission circuit  140 _ 1 . For the remaining LED emission circuits  140 _ 3 , . . . ,  140 _N, the VDD terminal is where that the DC power and the modulated signal are sent in analogous ways. For the first LED emission circuit  140 _ 1 , a VSS terminal is where that the DC power and the modulated signal are sent to the second LED emission circuit  140 _ 2 . For the second LED emission circuit  140 _ 2 , the VSS terminal is where that the DC power and the modulated signal are sent to the third LED emission circuit  140 _ 3 . For the remaining LED emission circuits  140 _ 4 , . . . ,  140 _N, the VSS terminal is where that the DC power and the modulated signal are sent in analogous ways. Namely, the VDD terminal is an input terminal and the VSS terminal is an output terminal for each of the LED emission circuits  140 . In addition, a VCC terminal is where that the DC voltage outputted from the voltage regulator unit  146  and is where that the DC voltage inputted to the above-mentioned units. 
     For more detailed expression, the VDD terminal is electrically connected to the VSS terminal though the voltage regulator unit  146 . Also, the VDD terminal is electrically connected to the amplifier unit  142  through the signal acquisition unit C. Also, the VDD terminal is electrically connected to the first constant current source  150 R through the red light LED  148 R. Also, the VDD terminal is electrically connected to the second constant current source  150 G through the green light LED  148 G Also, the VDD terminal is electrically connected to the third constant current source  150 B through the blue light LED  148 B. In addition, the filter unit  154  is electrically connected to the amplifier unit  142  through the demodulation unit  144 . The counter and shift register unit  158  is electrically connected to the filter unit  154  through the recognition and logic controller unit  156 . Also, the counter and shift register unit  158  is electrically connected to the output temporary storage unit  152  through the latch unit  153 . Also, the counter and shift register unit  158  is electrically connected to the second modulation unit  162  through the encoder unit  160 . In addition, the output temporary  152  is electrically connected to the first constant current source  150 R, the second constant current source  150 G, and the third constant current source  150 B, respectively. The second modulation unit  162  is electrically connected to the VSS terminal. 
     The operation procedure of the LED emission circuit  140  is explained as follows. The signal acquisition unit C (such as a capacitor) blocks the DC voltage in the VDD terminal to enter into the amplifier unit  142  and other units which process the AC signals. However, the modulated signal can only pass through the signal acquisition unit C. The DC voltage in the VDD terminal is provided to the voltage regulator unit  146  to generate a DC voltage VCC 2  outputted from a VCC terminal. Also, the DC voltage VCC 2  is supplied to drive other units. The DC power is sent from the VSS terminal of the voltage regulator unit  146  to the VDD terminal of the next LED emission circuit  140 . A DC component of the modulated signal sent from the VDD terminal is blocked by the signal acquisition unit C, and an AC component of the modulated signal is passed by the signal acquisition unit C. Afterward, the AC component of the modulated signal is amplified by the amplifier unit  142 . Afterward, the amplified modulated signal (only the AC component) is demodulated by the demodulation unit  144 . Afterward, the demodulated signal is restored to the original signal by the filter unit  154 . Afterward, the original signal is recognized to separate the data contents and clock, and the data contents are shifted in the counter and shift register unit  158 . After a number of signals are sent, the data contents of the counter and shift register unit  158  are latched to the output temporary storage unit  152  by the latch unit  153  when a defaulted end signal is received. The color and intensity of the red light LED  148 R, the green light LED  148 G, and the blue light  148 B are performed according to the data contents. In addition, the data contents are sent to the encoder unit  160  by the counter and shift register unit  158  to be encoded. Afterward, the encoded data contents are sent to the second modulation unit  162  to be modulated into a modulated signal. The modulated signal is sent to the next LED emission circuit  140  through the VSS terminal. More particularly, the first constant current source  150 R, the second constant current source  150 G, and the third constant current source  150 B provide the constant current and receive the data contents outputted from the output temporary storage unit  152 . 
     The above-mentioned modulation signal transmission is a serial-type modulated signal transmission. In addition, the above-mentioned modulation signal transmission can be implemented using a parallel-type modulated signal transmission. In order to implement the parallel-type modulated signal transmission, an automated numbered system is provided to assign numbers to each of the LED emission circuits  140 . Hence, the received address signals are compared to the assigned numbers of the LED emission circuit  140 . For example, the microcontroller unit  104  sends an address signal with number 0 to the first LED emission circuit  140 _ 1  when the LED control system is started up. Afterward, the address signal with number 0 is stored in the first LED emission circuit  140 _ 1  and the address signal is added by 1. Namely, the address signal with number 1 is sent from the second modulation unit  162  to the second LED emission circuit  140 _ 2 . Afterward, the address signal with number 1 is stored in the second LED emission circuit  140 _ 2  and the address signal is added by 1. Namely, the address signal with number 2 is sent from the second modulation unit  162  to the third LED emission circuit  140 _ 3 . The address signal is processed for the remaining LED emission circuits  140 _ 3 ,  140 _ 4 , . . . ,  14 _N in analogous ways. Finally, the address signal with number N is sent to the microcontroller unit  104 . Accordingly, the microcontroller unit  104  can recognize the amount of the LED emission circuits  140 , and each of the LED emission circuits  140  has been assigned numbers.  FIG. 8  is another internal block diagram of the LED emission circuit. Accordingly, the modulated signal is processed by the corresponding LED emission circuits  140  based on the assigned numbers. As shown in  FIG. 8 , an address register unit  166  is electrically connected to the recognition and logic controller unit  16 . 
     Reference is made to  FIG. 4  which is a timing sequence diagram of communicating a modulated signal between the LED emission circuits. The lower part of the  FIG. 4  shows the modulated signal which is sent to the Nth LED emission circuit  140 _N. Also, the sequence of the colors is not limited as shown in  FIG. 4 . As mentioned above, the data contents of the counter and shift register unit  158  are latched to the output temporary storage unit  152  through the latch unit  153  to control the color and intensity of the LEDs when the defaulted end signal END is received. In the same way, the modulated signal (shown in  FIG. 4 ) can be sent from the xth LED emission circuit  140 _x to the next LED emission circuit, namely the (x+1)th LED emission circuit  140 _(x+1). 
     Reference is made to  FIG. 5  which is a schematic view of a modulated signal (upper part) and a data signal (lower part). A sequence (0, 1, 1, 0) of the digital signal can be sent through the pulse width modulation (PWM) scheme. Also, the data signal can be modulated to generate the modulated signal. Reference is made to  FIG. 6A  which is a schematic view of an embodiment of a modulation unit (such as the first modulation unit  106 , and the second modulation unit  162 ). Also, reference is made to  FIG. 6B  which is a schematic view of an embodiment of a demodulation unit (such as the demodulation unit  144 ). 
     Reference is made to  FIG. 7  which is a block diagram of another embodiment of the LED control system using a modulated signal. The above-mentioned power conversion circuit  8  and the control circuit  10  can be integrated into a main control unit  10 A. A first LED lamp string apparatus  15 A includes the control unit  10 A and a first LED lamp string  14 A. A second LED lamp string apparatus  15 B includes the power conversion circuit  8  and a second LED lamp string  14 B. The main control unit  10 A generates a modulated signal, and the modulated signal can be sent to the first LED lamp string  14 A and the second LED lamp string  14 B. The power conversion circuit  8  provides the required power to the second LED lamp string  14 B. Accordingly, more LEDs can be simultaneously controlled. It assumes that a voltage drop across each of the LED emission circuits is 4 volts. Hence, there are about 27 (≈110÷4) LED emission circuits can be driven and controlled (in the embodiment as shown in  FIG. 1 ); there are about  54  (≈110÷4×2) LED emission circuits can be driven and controlled (in the embodiment as shown in  FIG. 7 ). 
     Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.