Abstract:
The present invention is relates to a control circuit for LED, especially relates to a multi-stages power supplying control circuit for LED. In the present invention, a diode is set among a plurality of LED units which connect in series. A voltage detecting circuit and a plurality of switching units can be integrated to switch each switching unit after detecting the voltage of the direct current power supply. Thus, the present invention can keep the same outputting power in different input voltage.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to a LED control circuit, and more particularly, the present invention relates to a LED multi-stages power supplying control circuit. 
         [0003]    2. Description of Related Art 
         [0004]    Recently, energy conservation and carbon reduction of environment-friendly awareness increases gradually. Since LED (Light Emitting Diode) has the characteristics of low energy consumption and high luminous efficiency, so get a good development in luminous field. 
         [0005]    In the past, manufacturers research and develop special specifications of LED lamps according to applying locations and fields. However, lamps in the same field still have different power designs in different countries, like vehicles lamps. Thus, manufacturers need to have different design specifications for one kind of lamp, and make costs increase. 
         [0006]    In lamps designs of some manufacturers, the switching power is integrated in lamps which configuration as show  FIG. 1 . The configuration includes a switching power supply circuit  12 , a plurality of LED  14 ,  16 , and a current limiter  18 . Wherein, the switching power supply circuit  12  is connected in series between the input terminal  101  and the output terminal  103 . A plurality of LED  14 ,  16  and the current limiter  18  are connected in series between the output terminal and the output terminal  103  of the switching power supply circuit  12 . The input voltage can be converted to the voltage suited for LED  14 ,  16  by the switching power supply circuit  12 , and the current can be limited in a safe range by the current limiter  18 . 
         [0007]    Although the configuration of the LED control circuit  10  can be applied in different power conditions or fields, but the switching power supply circuit  12  has larger volume, high costs, and results electromagnetic interference easily. Thus, these problems described above still need to be overcome. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, an object of the present invention is to provide a LED control circuit, especially relate to a LED multi-stages power supplying control circuit. 
         [0009]    Another object of the present invention is to provide a LED multi-stages power supplying control circuit which applies a plurality of switching units to switch the circuit path and achieve the function of constant-power supply. 
         [0000]    Another object of the present invention is to provide a LED multi-stages power supplying control circuit which can reduces costs and have no electromagnetic interference. 
         [0010]    To achieve the foregoing and other objects, a LED multi-stages power supplying control circuit is provided. The LED multi-stages power supplying control circuit comprises an input terminal and an output terminal, a plurality of LED units, at least a diode, at least an upper switching unit, at least a lower switching unit, and a voltage detecting circuit. The input terminal and the output terminal are connected to a direct current power supply and ground respectively. The LED units include first to (N+1)th LED units which connected in series between the input terminal and the output terminal sequentially. The diodes include first through Nth diodes, each diode is connected in series between the cathode of the corresponding LED unit and the anode of the next stage LED unit respectively. The upper switching units include first through Nth upper switching units, wherein each upper switching unit is connected between the input terminal and the cathode of the corresponding diode respectively. The lower switching units include first through Nth lower switching units, wherein each lower switching unit is connected between the anode of the diode and the output terminal respectively. The voltage detecting circuit is connected in series between the input terminal and the output terminal, and is connected to each upper switching unit and each lower switching unit for detecting the voltage of the direct current power supply, and the upper switching unit and the lower switching unit be set on or off according to the detecting results. Wherein, N being an integer ≧1. 
         [0011]    In one embodiment of the multi-stages power supplying control circuit, wherein each LED unit includes a current limiter respectively. 
         [0012]    In one embodiment of the multi-stages power supplying control circuit, wherein each switching unit includes a current limiter respectively. 
         [0013]    In one embodiment of the multi-stages power supplying control circuit, further including a variable current limiter, the variable current limiter changes the amount of the limited current according to the detecting results by the voltage detecting circuit, wherein the variable current limiter is connected in series between the cathode of (N+1)th LED unit and the output terminal, and is connected to the voltage detecting circuit. 
         [0014]    In one embodiment of the multi-stages power supplying control circuit, wherein each diode be replaced by a mid switching unit respectively, each mid switching unit is connected to the voltage detecting circuit respectively and be set on or off according to the detecting results by the voltage detecting circuit. 
         [0000]    In one embodiment of the multi-stages power supplying control circuit, wherein the corresponding upper switching unit and the lower switching unit be set on or off simultaneously. 
         [0015]    In one embodiment of the multi-stages power supplying control circuit, wherein when the corresponding upper switching unit and the lower switching unit be set on, the corresponding mid switching unit be set off; when the corresponding upper switching unit and the lower switching unit be set off, the corresponding mid switching unit be set on. 
         [0016]    In one embodiment of the multi-stages power supplying control circuit, wherein the LED units have the identical or similar operation voltage and operation current. In one embodiment of the multi-stages power supplying control circuit, wherein each LED unit be one LED or one set composed of multiple LED respectively. 
         [0017]    The present invention further provides a multi-stages power supplying control circuit for LED which comprises a input terminal and a output terminal, a first LED unit, a second LED unit, a serial-parallel switching module, and a voltage detecting circuit. The input terminal and the output terminal are connected to a direct current power supply and ground respectively. The anode of the first LED unit is connected to the input terminal. The cathode of the second LED unit is connected to the output terminal. The serial-parallel switching module is connected to the cathode of the first LED unit, the anode of the second LED unit, the input terminal, and the output terminal. The voltage detecting circuit is connected in series between the input terminal and the output terminal, and is connected to the serial-parallel switching module for detecting the voltage of the direct current power supply. The serial-parallel switching module is controlled to make the first LED unit and the second LED unit be in series connection or parallel connection according to the detecting results. 
         [0018]    In one embodiment of the multi-stages power supplying control circuit, wherein serial-parallel switching module includes a first upper switching unit, a first lower switching unit, a second upper switching unit, and a second lower switching unit. One terminal of the first upper switching unit is connected to the cathode of the first LED unit, another terminal of the first upper switching unit is connected to one terminal of the first lower switching unit, and another terminal of the first lower switching unit is connected to the anode of the second LED unit. One terminal of the second upper switching unit is connected to the cathode of the first LED unit, another terminal of the second upper switching unit is connected to the output terminal, one terminal of the second lower switching unit is connected to the anode of the second LED unit, another terminal of the second lower switching unit is connected to the input terminal. Wherein, each switching unit is connected to the voltage detecting circuit respectively, the switching unit be set on or off by the voltage detecting circuit according to the voltage detecting result of the direct current power supply. 
         [0019]    In one embodiment of the multi-stages power supplying control circuit, wherein the corresponding upper switching unit and the lower switching unit be set on or off simultaneously. 
         [0020]    In one embodiment of the multi-stages power supplying control circuit, wherein each LED unit be one LED or one set composed of multiple LED respectively. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
           [0022]      FIG. 1  is a schematic view illustrating a conventional LED control circuit. 
           [0023]      FIG. 2  is a schematic view illustrating a multi-stages power supplying control circuit according to one embodiment of the present invention. 
           [0024]      FIG. 3  is a schematic view illustrating a multi-stages power supplying control circuit according to another embodiment of the present invention. 
           [0025]      FIG. 4  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
           [0026]      FIG. 5  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
           [0027]      FIG. 6  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
           [0028]      FIG. 7  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
           [0029]      FIG. 8  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
           [0030]      FIG. 9  is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0031]    Other features and advantages of the invention will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described embodiments of this invention, simply by way of illustration of best modes to carry out the invention. 
         [0032]    Please refer to  FIG. 2  which is a schematic view illustrating a multi-stages power supplying control circuit according to one embodiment of the present invention. A multi-stages power supplying control circuit for LED of the present invention is suitable for multiple LED units and switches between multiple power supply voltages. As shown in  FIG. 2 , in the present embodiment, the multi-stages power supplying control circuit takes two LED units  24 ,  26  for example. The multi-stages power supplying control circuit  20  for LED of the present embodiment includes a input terminal  201 , a output terminal  203 , a voltage detecting circuit  22 , a first LED unit  24 , a second LED unit  26 , a diode  25 , a upper switching unit  281 , and a lower switching unit  283 . 
         [0033]    Wherein, the input terminal  201  and the output terminal  203  are connected to a direct current power supply (not shown) and ground respectively. The first LED unit  24  and the second LED unit  26  are connected in series between the input terminal  201  and the output terminal  203  sequentially. The diodes  25  are connected in series between first LED unit  24  and the second LED unit  26 . The upper switching unit  281  is connected between the input terminal  201  and the cathode of the diode  25 , and the lower switching unit  283  is connected between the anode of the diode  25  and the output terminal  203 . The voltage detecting circuit  22  is connected in series between the input terminal  201  and the output terminal  203 , and is connected to upper switching unit  281  and the lower switching unit  283  for detecting the voltage of the direct current power supply, and the upper switching unit  281  and the lower switching unit  283  be set on or off according to the detecting results. 
         [0034]    In one embodiment of the present invention, the operation voltages of the first LED unit  24  and the second LED unit  26  are set as 12V. In use, when the voltage of the direct current power supply is 24V that detected by the voltage detecting circuit  22 , the upper switching unit  281  and the lower switching unit  283  be set off. The first LED unit  24  and the second LED unit  26  are formed in the series connection, suited for 24V. 
         [0000]    When the voltage of the direct current power supply is 12V that detected by the voltage detecting circuit  22 , the upper switching unit  281  and the lower switching unit  283  be set on, and the first LED unit  24  and the second LED unit  26  are form in the parallel connection, suited for 12V. A diode  25  is disposed between the first LED unit  24  and the second LED unit  26  for inhibiting the reverse voltage and preventing the circuit from malfunctioning. 
         [0035]    Please refer to  FIG. 3  which is a schematic view illustrating a multi-stages power supplying control circuit according to another embodiment of the present invention. As shown in  FIG. 3 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  20  is similar to the embodiment shown in  FIG. 1 . The difference is that LED unit  24 ,  26  includes a current limiter  343 ,  363  respectively. 
         [0036]    The first LED unit  24  and the second LED unit  26  of the present embodiment further connect to a current limiter  343 ,  363  in series respectively except having the LED  341 ,  361  respectively. When the voltage of the direct current power supply is 24V, the first LED unit  24  and the second LED unit  26  are in series connection, wherein only one of the current limiter  343 ,  363  which with less current limiting value executes an action. When the voltage of the direct current power supply is 12V, the first LED unit  24  and the second LED units  26  are in parallel connection, the current limiter  343 ,  363  execute the current limit in the first LED unit  24  and the second LED unit  26  respectively. Thus, when the voltage being half, the integrated current are multiply, and keep the power of the integrated circuit equally. 
         [0037]    Please refer to  FIG. 4  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. As shown in  FIG. 4 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  40  is similar to the embodiment shown in  FIG. 1 . The difference is that each switching unit  281 ,  283  includes a current limiter  482 ,  484  respectively. 
         [0038]    In the upper switching unit  281  and the lower switching unit  283  of the present embodiment, being connected a current limiter  482 ,  484  in series respectively except having switching element. When the voltage of the direct current power supply is 24V, the first LED unit  24  and the second LED unit  26  are in series connection, the electric current pass through each LED unit  24 ,  26  directly. When the voltage of the direct current power supply is 12V, the first LED unit  24  and the second LED unit  26  are in parallel connection. The first LED unit  24  and the second LED unit  26  execute the current limit by the current limiter  482 ,  484  respectively. In addition, a current limiter  486  is still connected in series to the series circuit of LED unit  24  and LED unit  26  for preventing the current too large when the direct current voltage is 24V. 
         [0039]    Please refer to  FIG. 5  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. As shown in  FIG. 5 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  50  is similar to the embodiment shown in  FIG. 1 . The difference is that the circuit structure of the multi-stages power supplying control circuit for LED  50  further includes a variable current limiter  59 . 
         [0000]    In the present embodiment, the variable current limiter  59  is connected in series between the cathode of the second LED unit  26  and the output terminal  203 , and is connected to the voltage detecting circuit  22 . When the voltage of the direct current power supply is 24V, the first LED unit  24  and the second LED unit  26  are in series connection. The variable current limiter  59  being made at a first state, wherein the current is limited in 20 mA, for example. When the voltage of the direct current power supply is 12V, the first LED unit  24  and the second LED unit  26  are in parallel connection. The variable current limiter  59  being made at a second state, wherein the current is limited in 40 mA, for example. Therefore, the power of the integrated circuit can be keep equally. 
         [0040]    Please refer to  FIG. 6  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. In the present embodiment, the multi-stages power supplying control circuit takes four LED units  641 ,  643 ,  645 , and  647  for example. As shown in  FIG. 6 , the multi-stages power supplying control circuit for LED  60  of the present embodiment includes a input terminal  601 , a output terminal  603 , a voltage detecting circuit  62 , first through fourth LED units  641 - 647 , first to third diodes  661 - 665 , first to third upper switching units  681 ,  683 ,  685 , and first to third lower switching units  682 ,  684 ,  686 . 
         [0041]    Wherein, the input terminal  601  and the output terminal  603  are connected to the direct current power supply (not shown) and ground respectively. First through fourth LED units  641 - 647  are connected in series between the input terminal  601  and the output terminal  603  sequentially. First through third diodes  661 - 665  are connected in series between adjacent LED units  641 - 647  respectively. The first upper switching unit  681  is connected between the input terminal  601  and the cathode of the first diode  661 , and the first lower switching unit  682  is connected between the anode of the first diode  661  and the output terminal  603 . The second upper switching unit  683  is connected between the input terminal  601  and the cathode of the second diode  663 , and the second lower switching unit  684  is connected between the anode of the second diode  663  and the output terminal  603 . The third upper switching unit  685  is connected between the input terminal  601  and the cathode of the third diode  665 , and the third lower switching unit  686  is connected between the anode of the third diode  665  and the output terminal  603 . The voltage detecting circuit  62  is connected in series between the input terminal  601  and the output terminal  603 , and is connected to the upper switching unit  681 ,  683 ,  685  and the lower switching unit  682 ,  684 ,  686  for detecting the voltage of the direct current power supply, and the upper switching unit  681 ,  683 ,  685  and the lower switching unit  682 ,  684 ,  686  be set on or off according the detecting results. 
         [0042]    In one embodiment of the present invention, the operation voltages of the LED unit  641 - 647  are 12V. In use, when the voltage of the direct current power supply is 48V that detected by the voltage detecting circuit  62 , the upper switching unit  681 ,  683 ,  685  and the lower switching unit  682 ,  684 ,  686  be set off. The LED units  641 - 647  are formed in series connection, suited for 48V. 
         [0043]    When the voltage of the direct current power supply is 24V that detected by the voltage detecting circuit  62 , the first and third upper switching unit  681 ,  685  and the first and third lower switching unit  682 ,  686  be set off, and the second upper switching unit  683  and the second lower switching unit  684  be set on. Then, the first and the second LED units  641 ,  643  are formed in series connection, and the third and fourth LED units  645 ,  647  are formed in series connection, wherein the two series connections of the LED units are formed in parallel connection, suited for 24V. 
         [0044]    When the voltage of the direct current power supply is 12V that detected by the voltage detecting circuit  62 , the upper switching unit  681 ,  683 ,  685  and the lower switching unit  682 ,  684 ,  686  be set on. The LED units  641 - 647  are formed in parallel connection, suited for 12V. 
         [0045]    In the above embodiments as shown in  FIG. 3-5 , the current limiter can set in the LED units  641 - 647 , the switching unit  681 - 686  respectively, or a variable current limiter  69  can set between the cathode of the last stage LED unit  647  and the output terminal  603 , and changes the amount of the limited current according to the detecting results by the voltage detecting circuit  62 . 
         [0046]    Please refer to  FIG. 7  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. As shown in  FIG. 7 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  70  is similar to the embodiment shown in  FIG. 6 . The difference is that the connecting mode of the switching units  781 - 786  has some slight difference. 
         [0000]    The first upper switching unit  781  of the present embodiment is connected between the input terminal  601  and the cathode of the first diode  661 , the first lower switching unit  782  is connected between the anode of the first diode  661  and the anode of the second diode  663 . The second upper switching unit  783  is connected between the input terminal  601  and the cathode of the second diode  663 , the second lower switching unit  784  is connected between the anode of the second diode  663  and the output terminal  603 . The third upper switching unit  785  is connected between the cathode of the second diode  663  and the cathode of the third diode  665 , and the third lower switching unit  786  is connected between the anode of the third diode  665  and the output terminal  603 . 
         [0047]    When the voltage of the direct current power supply is 48V that detected by the voltage detecting circuit  62 , the upper switching unit  781 ,  783 ,  785  and the lower switching unit  782 ,  784 ,  786  be set off The LED units  641 - 647  are formed in series connection, suited for 48V. 
         [0048]    When the voltage of the direct current power supply is 24V that detected by the voltage detecting circuit  62 , the first and third upper switching units  781 ,  785  and the first and third lower switching unit  782 ,  786  be set off, and the second upper switching unit  783  and the second lower switching unit  784  be set on. Then, the first and the second LED unit  641 ,  643  are formed in series connection, and the third and fourth LED unit  645 ,  647  are formed in series connection. The two series connections of LED units are formed in parallel connection, suited for 24V. 
         [0049]    When the voltage of the direct current power supply is 12V that detected by the voltage detecting circuit  62 , the upper switching units  781 ,  783 ,  785  and the lower switching units  782 ,  784 ,  786  be set on. The LED units  641 - 647  are formed in parallel connection, suited for 12V. 
         [0050]    Thus, the above or other modes by changing the connection of the switching units to achieve the effects of the serial-parallel circuit are included within the scope of the present invention. 
         [0051]    Please refer to  FIG. 8  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. As shown in  FIG. 8 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  80  is similar to the embodiment shown in  FIG. 2 . The difference is that the diode  25  is replaced by a mid switching unit  85  in the present embodiment. 
         [0052]    In the present embodiment, a mid switching unit  85  is set between the first LED unit  24  and the second LED unit  85 . The mid switching unit  85  is connected to the voltage detecting circuit  22 , and be set on or off according the voltage detecting results of the direct current power supply. 
         [0053]    When the voltage of the direct current power supply is 24V that detected by the voltage detecting circuit  22 , the upper switching unit  281  and the lower switching unit  283  be set off, and the mid switching unit  85  be set on. The first LED unit  24  and the second LED unit  26  are formed in series connection, suited for 24V. 
         [0054]    When the voltage of the direct current power supply is 12V that detected by the voltage detecting circuit  22 , the upper switching unit  281  and the lower switching unit  283  be set on, and the mid switching unit  85  be set off. Then, the first LED unit  24  and the second LED unit  26  are formed in parallel connection, suited for 12V, wherein a disconnection can be formed between the first LED unit  24  and the second LED unit  26  by the mid switching unit  85  to prevent the circuit from malfunctioning. 
         [0055]    From the above operations, in the present invention, the corresponding upper switching unit and lower switching unit be set on or off simultaneously. The state of the mid switching unit  85  is contrast to the state of the corresponding upper switching unit  281  and the lower switching unit  283 . Thus, the signals for controlling the upper switching unit  281  and the lower switching unit  283  can be inverted by a inverter  87 , and then connects to the mid switching unit  85  for controlling. 
         [0056]    Please refer to  FIG. 9  which is a schematic view illustrating a multi-stages power supplying control circuit according to still another embodiment of the present invention. As shown in  FIG. 9 , in the present embodiment, the circuit structure of the multi-stages power supplying control circuit for LED  90  is similar to the embodiment shown in  FIG. 2 . The difference is that the present embodiment switches the serial-parallel connection of the circuit by using a serial-parallel switching module  98 . 
         [0057]    In the present embodiment, the serial-parallel switching module  98  is connected to the cathode of the first LED unit  24 , the anode of the second LED unit  26 , the input terminal  201 , and the output terminal  203 , and is connected to the voltage detecting circuit  22 . The voltage detecting circuit  22  can detect the voltage of the direct current power supply, and switches the serial-parallel switching module to make the first LED unit  24  and the second LED unit  26  be in series connection or parallel connection according to the detecting results. 
         [0058]    In one embodiment of the present invention, the serial-parallel switching module  98  includes a first upper switching unit  981 , a first lower switching unit  983 , a second upper switching unit  985 , and the second lower switching unit  987 . Wherein, one terminal of the first upper switching unit  981  is connected to the cathode of the first LED unit  24 , another terminal of the first upper switching unit  981  is connected to one terminal of the first lower switching unit  983 , and another terminal of the first lower switching unit  983  is connected to the anode of the second LED unit  26 . One terminal of the second upper switching unit  985  is connected to the cathode of the first LED unit  24 , another terminal of the second upper switching unit  985  is connected to the output terminal  203 , one terminal of the second lower switching unit  987  is connected to the anode of the second LED unit  26 , and another terminal of the second lower switching unit  987  is connected to the input terminal  201 . The switching units  981 - 987  are connected to the voltage detecting circuit  22  respectively, and the switching units  981 - 987  be set on or off according to the voltage detecting results of the direct current power supply. 
         [0059]    By using the serial-parallel switching module  98 , when the detecting voltage of the power supply voltage is 24V, the first upper switching unit  981  and the first lower switching unit  983  be set on, and the second upper switching unit  985  and the second lower switching unit  987  be set off. Then, the first LED unit  24  and the second LED unit  26  are in series connection, suited for 24V. 
         [0060]    When the detecting voltage of the power supply voltage is 12V, the first upper switching unit  981  and the first lower switching unit  983  be set off, and the second upper switching unit  985  and the second lower switching unit  987  be set on. Then, the first LED unit  24  and the second LED unit  26  are in parallel connection, suited for 12V. 
         [0061]    In one embodiment of the present invention, the serial-parallel switching module  98  can be implement by applying one mechanical type slide switch which be switched according the judgment of a user without the voltage detecting circuit  22 . 
         [0062]    In the above embodiments of the present invention, the LED units have the identical or similar operation voltage and operation current respectively. Each LED unit be one LED or one set composed of multiple LED respectively. Wherein, the current limiter can be replaced by a constant current component, and achieves more accurate effects for current controlling. 
         [0063]    The above embodiments although just take examples of two LED units and four LED units, but the embodiments of three LED units or more LED units can be understood based on the above implement principles. 
         [0064]    Although the description above contains many specifics, these are merely provided to illustrate the invention and should not be construed as limitations of the invention&#39;s scope. Thus it will be apparent to those skilled, in the art that various modifications and variations can be made in the system and processes of the present invention without departing from the spirit or scope of the invention.