WO2022095664A1 - Led驱动系统及电子设备 - Google Patents

Led驱动系统及电子设备 Download PDF

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Publication number
WO2022095664A1
WO2022095664A1 PCT/CN2021/123116 CN2021123116W WO2022095664A1 WO 2022095664 A1 WO2022095664 A1 WO 2022095664A1 CN 2021123116 W CN2021123116 W CN 2021123116W WO 2022095664 A1 WO2022095664 A1 WO 2022095664A1
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WO
WIPO (PCT)
Prior art keywords
led
circuit
switch
terminal
control
Prior art date
Application number
PCT/CN2021/123116
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English (en)
French (fr)
Inventor
任虎男
林荣镇
严丞辉
Original Assignee
北京显芯科技有限公司
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Publication of WO2022095664A1 publication Critical patent/WO2022095664A1/zh

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/54—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a series array of LEDs

Definitions

  • the embodiments of the present application relate to the field of LED display, and in particular, to an LED driving system and an electronic device.
  • LCD TVs liquid crystal televisions
  • LED Light Emitting Diode
  • mini-LEDs are often used in LCD TVs to enhance display effects.
  • LED backlight can be used to improve the color performance of LCD TV display by arranging hundreds or even thousands of LEDs.
  • Embodiments of the present application provide an LED driving system and an electronic device to solve the technical problem in the prior art that a circuit failure is easily caused when the LED driving current is relatively large.
  • an embodiment of the present application provides an LED driving system, where the LED driving system includes an LED circuit board;
  • the LED circuit board includes an LED driver and an LED
  • the LED driver includes a control circuit and a switch circuit
  • the switch circuit is used to control the brightness of the LED
  • the control circuit is connected to the control terminal of the switch circuit, and is used to control the on-off of the switch circuit;
  • the other ends of the switch circuit except the control end are provided separately from the ground end of the control circuit inside the LED driver.
  • the LED driving system further includes other circuit boards;
  • the ground terminal of the switch circuit and the ground terminal of the control circuit are connected on the other circuit boards.
  • the LED driving system further includes a driving circuit board
  • the drive circuit board includes a first power circuit for powering the control circuit and a second power circuit for powering the LED.
  • the switch circuit includes a switch tube, and the switch tube includes a control terminal, a first terminal, and a second terminal;
  • the first end of the switch tube is connected with one end of the LED controlled by the switch tube, and the second end of the switch tube is connected with the second power supply circuit;
  • the ground terminal of the control circuit is connected to the ground of the first power supply circuit.
  • the other end of the LED controlled by the switch tube is connected to the positive voltage end of the second power supply circuit
  • the second end of the switch tube is connected to the ground or the negative voltage end of the second power supply circuit.
  • the number of the switch tubes in the switch circuit is two
  • the number of LEDs controlled by the switch circuit is multiple
  • some of the LEDs in the multiple LEDs are switched by two switches
  • the first switch in the tube is controlled, and the remaining LEDs are controlled by the second switch;
  • the second end of the first switch tube and the second end of the second switch tube are both connected to the ground terminal of the second power supply circuit.
  • the LED controlled by the first switch tube is connected to the positive voltage terminal of the second power supply circuit, and the LED controlled by the second switch tube is connected to the positive voltage terminal of the second power supply circuit.
  • the voltage of the positive voltage terminal of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage terminal.
  • the first switch tube is an NMOS transistor
  • the second switch tube is a PMOS transistor; the signal sent to the control terminal of the NMOS transistor and the signal sent to the control terminal of the PMOS transistor identical or complementary.
  • the LED controlled by the switch tube is one LED, or an LED string formed by connecting multiple LEDs in series.
  • an embodiment of the present application provides an electronic device, including the LED driving system and the liquid crystal panel described in any one of the first aspect.
  • the LED drive system and electronic device provided by the embodiments of the present application include an LED circuit board, the LED circuit board includes an LED driver and an LED, the LED driver includes a control circuit and a switch circuit, and the switch circuit is used to control the LED
  • the control circuit is connected to the control terminal of the switch circuit to control the on-off of the switch circuit.
  • the other terminals of the switch circuit except the control terminal are connected to the ground terminal of the control circuit.
  • FIG. 1 is a schematic diagram of an application scenario provided by an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of an LED driving circuit provided by an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of an LED driver according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of current and voltage changes of the circuits shown in FIGS. 2 and 3;
  • FIG. 5 is a schematic structural diagram of an LED driving system according to Embodiment 1 of the present application.
  • FIG. 6 is a schematic structural diagram of another LED driving system provided in Embodiment 1 of the present application.
  • FIG. 7 is a schematic structural diagram of an LED driving system according to Embodiment 2 of the present application.
  • FIG. 8 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 7;
  • FIG. 9 is a schematic structural diagram of an LED driving system according to Embodiment 3 of the present application.
  • FIG. 10 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 9;
  • FIG. 11 is a schematic structural diagram of an LED driving system according to Embodiment 4 of the present application.
  • FIG. 12 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 11 .
  • the words “if”, “if” as used herein may be interpreted as “at” or “when” or “in response to determining” or “in response to detecting”.
  • the phrases “if determined” or “if detected (the stated condition or event)” can be interpreted as “when determined” or “in response to determining” or “when detected (the stated condition or event),” depending on the context )” or “in response to detection (a stated condition or event)”.
  • FIG. 1 is a schematic diagram of an application scenario provided by an embodiment of the present application.
  • an LED and a liquid crystal panel may be provided in the display device, the LED is used to provide a backlight function, and the arrow in the figure indicates that the light emitted by the LED can act on the liquid crystal panel.
  • the LED driver is connected to the LED and can control the brightness of the LED.
  • the number of LEDs can be multiple, and the light emitted by the multiple LEDs is matched with the image displayed by the liquid crystal panel, which can improve the display effect.
  • FIG. 2 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present application.
  • an LED driver LED Driver
  • an LED can be arranged on the LED circuit board (LED Board).
  • the embodiments of the present application are described by taking one LED driver driving two LEDs as an example.
  • the two LEDs are denoted D1 and D2, respectively.
  • the LED is powered by an AC/DC (AC to DC) circuit provided on the Driving Board.
  • AC/DC AC to DC
  • the LED driver may include a control circuit and an NMOS (N-Metal-Oxide-Semiconductor, N-type metal-oxide-semiconductor) transistor.
  • the control circuit may be a digital & analog circuit (Digital Circuit & Analog Circuit).
  • One end of the transistor is connected to the LED, the other end VSS_LED is grounded, the LED is connected to the AC/DC circuit, and has a supply voltage V_LED.
  • V_LED supply voltage
  • the control terminal of the transistor is connected with the control circuit, so that the control circuit can control the on-off of the transistor.
  • the control circuit is powered by a DC/DC (direct current to direct current) circuit on the drive circuit board.
  • the power supply terminal VDD of the control circuit is connected to the DC/DC circuit on the driving circuit board
  • the ground terminal GND of the control circuit is connected to the ground terminal VSS_LED of the transistor
  • VSS_LED is connected to the ground on the driving circuit board.
  • the LED driver can realize the driving of the LED through a PWM (Pulse Width Modulation, pulse width modulation) signal.
  • PWM Pulse Width Modulation, pulse width modulation
  • FIG. 3 is a schematic structural diagram of an LED driver according to an embodiment of the present application.
  • the control circuit may include a bandgap reference circuit, a PWM output circuit, resistors R1 and R2, an operational amplifier U1, and the like.
  • the bandgap reference circuit can provide a bandgap reference
  • the PWM output circuit can output a PWM signal, so as to control the NMOS transistors and adjust the light-emitting states of D1 and D2.
  • the supply voltage and current of the LED are V_LED and I_LED respectively, and the LED driver has a power supply terminal VDD.
  • FIG. 4 is a schematic diagram of current and voltage changes of the circuits shown in FIGS. 2 and 3 .
  • the voltage and current changes in Figure 4 apply to both Figures 2 and 3.
  • t represents time, and the current I_LED flowing through the LED changes with the change of the PWM signal.
  • an embodiment of the present application provides an LED driving system, which separates the ground terminal VSS_LED of the transistor and the ground terminal GND of the control circuit.
  • VSS_LED and GND are not connected in the LED circuit board, they are connected together away from the LED board, so that the ground bounce of the LED driving loop will not interfere with the high and low levels of the control circuit, thus ensuring the normal operation of the circuit.
  • Embodiment 1 of the present application provides an LED driving system.
  • FIG. 5 is a schematic structural diagram of an LED driving system according to Embodiment 1 of the present application. As shown in FIG. 5 , the LED driving system may include an LED circuit board;
  • the LED circuit board includes an LED driver and an LED
  • the LED driver includes a control circuit and a switch circuit
  • the switch circuit is used to control the brightness of the LED
  • the control circuit is connected to the control terminal of the switch circuit, and is used to control the on-off of the switch circuit;
  • the other ends of the switch circuit except the control end are provided separately from the ground end of the control circuit inside the LED driver.
  • the circuit board described in the embodiments of the present application may be PCB (Printed Circuit Board, printed circuit board), glass (Glass) or wafer (Wafer).
  • An LED driver and an LED are provided on the LED circuit board.
  • the number of LEDs and LED drivers can be one or more, and one LED driver can control one LED or multiple LEDs.
  • the LEDs can be mini-LEDs or ordinary LEDs.
  • the ground terminal of the control circuit and each terminal of the switch circuit may be separately arranged inside the LED driver.
  • the separate arrangement described in the embodiments of the present application means that they are not directly connected together by wires, and the wires may include wirings on a PCB.
  • each terminal of the switch circuit does not need to be directly connected to the ground terminal of the control circuit. If the switch circuit includes a ground terminal, the ground terminal of the switch circuit and the ground terminal of the control circuit may be provided separately.
  • a specific implementation solution of the separate setting inside the LED driver is to separate the setting on the LED circuit board. It can be understood that since the LED driver is arranged on the LED circuit board, then, if the LED driver is arranged separately on the LED circuit board, it is naturally arranged separately inside the LED driver.
  • the ground terminal of the switch circuit and the ground terminal of the control circuit can be connected on the other circuit boards, especially in the power supply circuit. connection on the circuit board.
  • the LED driving system may include multiple circuit boards, the LED driver and the LED may be located on one circuit board, other circuits may be located on other circuit boards, and the ground terminals of the control circuit and the switch circuit in the LED driver may be located on other circuits connection on the board.
  • ground terminal of the switch circuit and the ground terminal of the control circuit can also be connected at other places away from the LED circuit board, for example, they can be connected on the housing of the LED driving system.
  • FIG. 6 is a schematic structural diagram of another LED driving system according to Embodiment 1 of the present application.
  • the difference between the solution shown in FIG. 6 and the solution shown in FIG. 5 is that the ground terminal of the control circuit and the ground terminal of the switch circuit can be connected together on the LED circuit board.
  • the LED driver and the LED are arranged on the LED circuit board, and the ground terminal of the control circuit in the LED driver and the ground terminal of the switch circuit are separately arranged inside the LED driver, but it is not necessary to Separate settings on the LED circuit board.
  • the ground terminal of the control circuit and the ground terminal of the switch circuit can be connected together outside the LED driver, and then connected to the ground on other circuit boards.
  • the solution shown in FIG. 6 can be used, and when the resistance is large, the solution shown in FIG. 5 can be used, thereby realizing a more flexible circuit design solution.
  • the LED driving system provided in this embodiment includes an LED circuit board, the LED circuit board includes an LED driver and an LED, the LED driver includes a control circuit and a switch circuit, and the switch circuit is used to control the brightness of the LED, so
  • the control circuit is connected to the control terminal of the switch circuit, and is used to control the on-off of the switch circuit.
  • the other terminals of the switch circuit except the control terminal are connected to the ground terminal of the control circuit at the LED.
  • the driver is internally separated, so that the ground terminal of the control circuit is kept away from the LED circuit as far as possible, and the influence of the large current of the LED on the ground terminal of the control circuit is reduced, so that the ground bounce of the LED circuit does not interfere with the voltage of the control circuit as much as possible, thereby reducing the circuit caused by the ground bounce. failure, improve the stability of equipment work.
  • the second embodiment of the present application provides an LED driving system.
  • the ground terminal of the control circuit and the ground terminal of the switch circuit are connected on the driving circuit board.
  • the LED driving system may include an LED circuit board; the LED circuit board includes an LED driver and an LED; the LED driver includes a control circuit and a switch circuit; the switch circuit is used to control the brightness of the LED; The control circuit is connected to the control terminal of the switch circuit, and is used to control the on-off of the switch circuit; the other terminals of the switch circuit except the control terminal are connected to the ground terminal of the control circuit at the LED. Drive internal separation settings.
  • the LED driving system may include a driving circuit board; the driving circuit board includes a first power supply circuit for supplying power to the control circuit and a second power supply circuit for supplying power to the LED.
  • the first power supply circuit may be a DC-to-DC circuit
  • the second power supply circuit may be an AC-to-DC circuit to meet different power supply requirements of the control circuit and the LED.
  • the ground terminal of the switch circuit and the ground terminal of the control circuit can be connected on the driving circuit board, which can effectively reduce the influence of the large LED current on the ground terminal of the control circuit on the basis of realizing unified grounding.
  • the switch circuit may include a switch tube, the switch tube includes a control end, a first end and a second end; the first end of the switch tube is connected to one end of the LED controlled by the switch tube, so the The second end of the switch tube is connected to the second power circuit.
  • the other end of the LED controlled by the switch tube is connected to the positive voltage terminal of the second power supply circuit; the second end of the switch tube can be specifically used as a ground terminal and is connected to the ground terminal of the second power supply circuit, thereby form a loop.
  • FIG. 7 is a schematic structural diagram of an LED driving system according to Embodiment 2 of the present application. As shown in FIG. 7 , an LED driver and an LED are arranged on the LED circuit board.
  • the LED driver includes a control circuit and a switch circuit.
  • the switch circuit includes a switch tube, and the switch tube may specifically be an NMOS transistor in the figure.
  • a first power supply circuit and a second power supply circuit are arranged on the driving circuit board.
  • the port of the LED driver may include the power supply terminal VDD of the control circuit, the ground terminal GND, the second terminal VSS_LED of the switch tube, and the first terminal for connecting with the LED.
  • the switch tube is an NMOS transistor
  • the gate of the NMOS transistor is the control terminal connected to the control circuit
  • the drain is the first terminal connected to the LED
  • the source is used to connect to the second power supply. the second end of the circuit connection.
  • the switch circuit may also include other devices capable of implementing the switch function, such as PMOS transistors, triodes, and the like.
  • the power terminal may refer to a port for outputting or receiving a positive voltage of the power supply
  • the ground terminal may refer to a port used for grounding.
  • the power supply terminal VDD of the control circuit is connected to the power supply terminal of the first power supply circuit
  • the ground terminal GND of the control circuit is connected to the ground of the first power supply circuit.
  • the LED driver may also include other ports not shown, such as a communication port and the like.
  • the LED controlled by the switch tube is one LED, or an LED string formed by connecting multiple LEDs in series.
  • the switch tube controls multiple LEDs the positive and negative electrodes of the multiple LEDs are connected in sequence to form an LED string in series.
  • One end of the LED string refers to the negative electrode of the first LED, and the other end refers to the last LED.
  • the positive pole of an LED is one LED, or an LED string formed by connecting multiple LEDs in series.
  • D1 and D2 in the two LEDs are connected in series.
  • the first terminal of the switch tube is connected to the negative terminal of D2
  • the second terminal VSS_LED is connected to the ground of the second power supply circuit
  • the positive terminal of D1 is connected to the positive voltage terminal of the second power supply circuit to form a closed loop.
  • the control circuit can control the on-off of the switch tube. Specifically, the control circuit is connected to the control end of the switch tube, and controls the on or off of the switch tube by sending a PWM signal to the control end.
  • control circuit can be used to implement other functions, such as communicating with a controller, in addition to controlling the switch.
  • control circuits all or part of the circuits in the LED driver except the switch tubes may be referred to as control circuits.
  • the other ends of the switch tube except the control end are separated from the ground end GND of the control circuit and arranged inside the LED driver.
  • a certain end of the switch tube such as VSS_LED, needs to be connected to the ground, it can be connected to the ground terminal GND of the control circuit on the driving circuit board.
  • the ground of the first power supply circuit and the ground of the second power supply circuit will be connected together. Therefore, the VSS_LED of the switch tube and the ground terminal GND of the control circuit are connected to the ground of the first power supply circuit and the second power supply respectively.
  • the ground of the circuit, which is equivalent to the VSS_LED of the switch tube and the ground terminal GND of the control circuit are finally connected together.
  • FIG. 8 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 7 .
  • t represents time, and the current I_LED flowing through the LED varies with the PWM signal.
  • I_LED is positive, and I_LED is 0 at other times.
  • the voltage of the second end VSS_LED of the switch circuit changes with the change of the current I_LED.
  • VSS_LED is also 0; when I_LED is positive, VSS_LED rises to greater than 0, and the specific size is the same as VSS_LED to the second power supply
  • the ground resistance of the circuit is related.
  • the ground terminal GND of the control circuit is set apart from the second terminal VSS_LED of the switch circuit, the voltage of the ground terminal GND of the control circuit is less affected by I_LED, and its voltage fluctuation is not large, and is conventionally set to 0.
  • the voltage of the power supply terminal VDD of the control circuit basically does not change, so the voltage difference between the power supply terminal VDD of the control circuit and the ground terminal GND remains basically unchanged, which can improve the stability of the control circuit operation.
  • the LED driving system includes an LED circuit board and a driving circuit board, the LED circuit board includes an LED driver and an LED, and the driving circuit board includes a first power supply circuit for supplying power to the control circuit and a power supply circuit for powering the control circuit.
  • the switch circuit includes a switch tube, the switch tube includes a control end, a first end and a second end, and the first end of the switch tube is controlled by the switch tube One end of the LED is connected to one end of the switch tube, the other end of the LED controlled by the switch tube is connected to the positive voltage terminal of the second power supply circuit, and the second end of the switch tube is connected to the ground of the second power supply circuit.
  • the ground terminal of the control circuit is connected to the ground of the first power supply circuit, so that the ground terminal of the control circuit and the ground terminal of the switch circuit are connected on the driving circuit board away from the LED driver, which can further reduce the voltage variation of the ground terminal of the control circuit , reduce ground bounce and improve system stability.
  • FIG. 9 is a schematic structural diagram of an LED driving system according to Embodiment 3 of the present application.
  • the difference between this embodiment and the second embodiment is that the second end VSS_LED of the switch tube does not need to be connected to the ground, that is, it does not need to be 0.
  • an LED driver and an LED are arranged on the LED circuit board, and a first power supply circuit and a second power supply circuit are arranged on the driving circuit board.
  • the LED driver includes a control circuit and a switch circuit.
  • the ports of the LED driver may include the power supply terminal VDD and the ground terminal GND of the control circuit, and also include the second terminal VSS_LED of the switch tube and a port for connecting with the LED.
  • the power supply terminal VDD of the control circuit is connected to the power supply terminal of the first power supply circuit, and the ground terminal GND of the control circuit is connected to the ground of the first power supply circuit.
  • the switch tube can be an NMOS transistor, and D1 and D2 in the two LEDs are connected in series.
  • the first terminal of the switch tube is connected to the negative terminal of D2
  • the second terminal VSS_LED is connected to the ground of the second power supply circuit
  • the positive terminal of D1 is connected to the positive voltage terminal of the second power supply circuit to form a closed loop.
  • the other ends of the switch tube except the control end are separated from the ground end GND of the control circuit and arranged inside the LED driver.
  • the second end VSS_LED of the switch tube may not necessarily be connected to the ground, and thus may have a voltage not equal to 0.
  • the second terminal VSS_LED of the switch tube may be connected to the negative voltage terminal of the second power supply circuit.
  • the positive voltage terminal may refer to a port whose output voltage is greater than 0, and the negative voltage terminal may refer to a port whose output voltage is less than 0.
  • the difference between the positive voltage output by the positive voltage terminal of the second power supply module and the negative voltage output by the negative voltage terminal of the second power supply module may be equal to the voltage difference required for the LED to work normally, So as to ensure that the LED is normally driven.
  • the output voltage of the negative voltage terminal and the output voltage of the positive voltage terminal may be opposite numbers to each other, the positive voltage output by the second power supply circuit may be V_LED/2, and the output negative voltage may be -V_LED/2. Simplify the power supply circuit and improve the system performance under the condition of ensuring the differential pressure.
  • FIG. 10 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 9 .
  • t represents time, and the current I_LED flowing through the LED varies with the PWM signal.
  • I_LED is positive, and I_LED is 0 at other times.
  • the voltage of the second end VSS_LED of the switch circuit changes with the change of the current I_LED.
  • I_LED the voltage of VSS_LED is -V_LED/2; when I_LED is positive, the voltage of VSS_LED is slightly greater than - V_LED/2, the specific size is related to the resistance value of VSS_LED to the ground of the second power supply circuit.
  • the ground terminal GND of the control circuit is basically unaffected when I_LED changes, and is agreed at 0.
  • the voltage of the power supply terminal VDD of the control circuit basically does not change, so the voltage difference between the power supply terminal VDD of the control circuit and the ground terminal GND remains basically unchanged, which can improve the stability of the control circuit operation.
  • the structure, function, connection relationship of other devices can refer to the solution in the second embodiment.
  • the ground terminal of the control circuit is connected to the ground of the first power supply circuit
  • the second terminal of the switch tube is connected to the negative voltage terminal of the second power supply circuit, thereby switching on
  • the circuit does not need to be connected to the ground, that is, it does not need to be 0V, which provides a greater degree of freedom for circuit design.
  • the second end of the switch tube can use any voltage, which can be designed according to actual needs on the basis of improving system stability. The voltage of the switch tube meets the application requirements of different scenarios.
  • the fourth embodiment of the present application provides an LED driving system.
  • the switch circuit may include a plurality of switch tubes, which control different LEDs respectively.
  • the number of the switch tubes in the switch circuit is two
  • the number of LEDs controlled by the switch circuit is multiple
  • some of the LEDs in the multiple LEDs are controlled by the first one of the two switch tubes.
  • the switch tube is controlled, and the remaining LEDs are controlled by the second switch tube; the first end of the first switch tube and the first end of the second switch tube are both connected to the LED, and the first switch tube Both the second end and the second end of the second switch tube are connected to the ground end of the second power circuit.
  • the LED controlled by the first switch tube is connected to the positive voltage terminal of the second power supply circuit, and the LED controlled by the second switch tube is connected to the negative voltage terminal of the second power supply circuit;
  • the absolute value of the voltage of the positive voltage terminal of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage terminal.
  • FIG. 11 is a schematic structural diagram of an LED driving system according to Embodiment 4 of the present application.
  • an LED driver and an LED are arranged on the LED circuit board, and a first power supply circuit and a second power supply circuit are arranged on the driving circuit board.
  • the LED driver includes a control circuit and a switch circuit.
  • the control circuit includes a power supply terminal VDD and a ground terminal GND, the power supply terminal VDD of the control circuit is connected to the power supply terminal of the first power supply circuit, and the ground terminal GND of the control circuit is connected to the ground of the first power supply circuit.
  • the switch circuit includes two switch tubes, optionally, the first switch tube may be an NMOS transistor in the figure, and the second switch tube may be a PMOS (P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor type metal-oxide-semiconductor) transistors.
  • PMOS P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor, P-Metal-Oxide-Semiconductor type metal-oxide-semiconductor
  • the second end of the first switch tube is connected to the second end of the second switch tube, denoted as VSS_LED, and VSS_LED is connected to the ground of the second power supply circuit.
  • the first switch tube and the second switch tube control different LEDs, denoted as D1 and D2 respectively.
  • the first end of the first switch tube is connected to the negative pole of D1
  • the positive pole of D1 is connected to the positive voltage terminal of the second power supply circuit
  • the first end of the second switch tube is connected to the positive pole of D2
  • the positive pole of D2 The negative electrode is connected to the negative voltage terminal of the second power supply circuit to form a closed loop.
  • the voltages output by the positive voltage terminal and the negative voltage terminal of the second power supply circuit are V_LED/2 and -V_LED/2, respectively.
  • the circuit where D1 is located is turned on or off, thereby controlling the on and off of D1.
  • the circuit where D2 is located is turned on or off, thereby controlling the on and off of D2.
  • the control circuit can control the on-off of the two switches.
  • the control circuit may be connected to the control terminals of the two switching tubes respectively, and the switching tubes are controlled to be turned on or off by sending PWM signals to the control terminals of the two switching tubes respectively.
  • the signal sent to the control terminal of the NMOS transistor is the same as or complementary to the signal sent to the control terminal of the PMOS transistor.
  • the brightness changes of the two LEDs are complementary, that is, when one LED is on, the other LED is off;
  • complementary PWM signal is input to the control terminal, the PMOS transistor and the NMOS transistor are turned on at the same time, and the brightness changes of the two LEDs are the same.
  • complementary may refer to high and low level complementarity, that is, when one signal is high, the other signal is low.
  • the positive voltage output by the second power supply circuit may be V_LED/2, and the output negative voltage may be -V_LED/2, so that the two LEDs have the same voltage drop and ensure the normal operation of each LED.
  • FIG. 12 is a schematic diagram of current and voltage changes of the LED driving system shown in FIG. 11 .
  • t represents time
  • the current I_LED flowing through the LED varies with the PWM signal.
  • I_LED is positive
  • I_LED is 0 at other times.
  • VSS_LED The voltage of the second end of the switch tube VSS_LED changes with the change of the current I_LED.
  • I_LED the voltage of VSS_LED is 0; when I_LED is positive, the voltage of VSS_LED is slightly greater than 0 due to the current passing through. It is related to the resistance value of VSS_LED to the ground of the second power circuit.
  • the ground terminal GND of the control circuit is set apart from the second terminal VSS_LED of the switch circuit, the voltage of the ground terminal GND of the control circuit is less affected by I_LED, and its voltage fluctuation is not large, approximately equal to 0.
  • the voltage of the power supply terminal VDD of the control circuit basically does not change, so the voltage difference between the power supply terminal VDD of the control circuit and the ground terminal GND remains basically unchanged, which can improve the stability of the control circuit operation.
  • the switch circuit includes two switch tubes
  • the structures, functions, and connection relationships of other devices may refer to the solutions in the second and third embodiments.
  • the number of switch tubes in the switch circuit is two, and the number of LEDs controlled by the switch circuit is multiple, wherein some of the LEDs in the multiple LEDs are controlled by the first one of the two switch tubes.
  • One switch tube is controlled, and the remaining LEDs are controlled by the second switch tube; the first end of the first switch tube and the first end of the second switch tube are both connected to the LED, and the first switch tube
  • the second end of the tube and the second end of the second switch tube are both connected to the ground terminal of the second power supply circuit, and the LED controlled by the first switch tube is connected to the positive voltage of the second power supply circuit
  • the LED controlled by the second switch is connected to the negative voltage terminal of the second power supply circuit; the voltage of the positive voltage terminal of the second power supply circuit is equal to the absolute value of the voltage of the negative voltage terminal, so that through different
  • the switch tubes control different LEDs, and the second end of each switch tube does not affect the ground terminal GND of the control circuit, which increases the flexibility of LED control on the basis of reducing circuit malfunction
  • the voltage and current values of each device of the LED drive system can be designed according to actual needs.
  • the voltage value of the power supply terminal VDD of the control circuit can be 1.8V to 5V
  • V_LED can be 10V to 80V
  • VSS_LED can be designed to be 0V or -V_LED/2
  • I_LED can be 1mA to 120mA
  • the frequency of the PWM signal can be It is 60Hz ⁇ 4kHz.
  • the switch circuit may include one or more switch tubes. It can be understood that each end of the switch circuit may include each end of the one or more switch tubes.
  • the control end of the switch circuit may include the control end of the switch tube. In the case where the switch circuit includes multiple switch tubes, there may be multiple control terminals of the switch circuit.
  • the circuit can be appropriately adjusted according to actual needs, such as adjusting the transistors to triodes, adjusting the power supply circuit to other types of power supply circuits, adding more switch tubes, and so on. This embodiment of the present application does not limit this.
  • Embodiments of the present application further provide an electronic device, including the LED driving system and the liquid crystal panel described in any of the above embodiments.
  • the LED driving system is used to provide backlight for the liquid crystal panel.
  • the electronic device may be any device with a display function, such as an LCD TV.
  • the disclosed apparatus and method may be implemented in other manners.
  • the device embodiments described above are only illustrative.
  • the division of the modules is only a logical function division. In actual implementation, there may be other division methods.
  • multiple modules may be combined or integrated. to another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or modules, and may be in electrical, mechanical or other forms.
  • modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, may be located in one place, or may be distributed to multiple units. Some or all of the modules may be selected according to actual needs to implement the solution of this embodiment.
  • each functional module in each embodiment of the present application may be integrated in one processing unit, or each module may exist physically alone, or two or more modules may be integrated in one unit.

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Abstract

本申请提供一种LED驱动系统及电子设备，其中，LED驱动系统包括LED电路板；LED电路板包括LED驱动器和LED；LED驱动器包括控制电路和开关电路；开关电路用于控制LED的亮度；控制电路与开关电路的控制端连接，用于控制开关电路的通断；开关电路除控制端以外的其它端均与控制电路的接地端在LED驱动器内部分离设置。本申请提供的LED驱动系统及电子设备，能够减轻LED大电流对控制电路接地端的影响，使得LED回路的接地弹跳尽量不干扰控制电路的电压，从而减少因接地弹跳引发的电路故障，提高设备工作的稳定性。

Description

LED驱动系统及电子设备
本申请要求于2020年11月03日提交中国专利局、申请号为202011209435.9、申请名称为“LED驱动系统及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及LED显示领域，尤其涉及一种LED驱动系统及电子设备。
背景技术
随着电子科技的不断发展，具有图像显示功能的各种电子设备如液晶电视(LCD TV)等的性能不断增强，应用也越来越广泛。
目前，在液晶电视中常常利用发光二极管(Light Emitting Diode，LED)或者mini-LED来增强显示效果。例如，可以采用LED背光(Backlight)的方式，通过设置数百个乃至数千个LED，增进液晶电视显示的色彩表现。
在基于LED的背光系统中，LED的驱动电流较大时容易导致接地弹跳(Ground Bouncing)，接地弹跳容易引发电路故障，使设备无法正常工作。
发明内容
本申请实施例提供一种LED驱动系统及电子设备，以解决现有技术中LED的驱动电流较大时容易导致电路故障的技术问题。
第一方面，本申请实施例提供一种LED驱动系统，所述LED驱动系统包括LED电路板；
所述LED电路板包括LED驱动器和LED；
所述LED驱动器包括控制电路和开关电路；
所述开关电路用于控制所述LED的亮度；
所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断；
所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置。
在一种可能的实施方式中，所述LED驱动系统还包括其它电路板；
所述开关电路的接地端与所述控制电路的接地端在所述其它电路板上连接。
在一种可能的实施方式中，所述LED驱动系统还包括驱动电路板；
所述驱动电路板包括用于为所述控制电路供电的第一电源电路以及用于为所述LED供电的第二电源电路。
在一种可能的实施方式中，所述开关电路包括开关管，所述开关管包括控制端、第一端以及第二端；
所述开关管的第一端与所述开关管控制的LED的一端连接，所述开关管的第二端 与所述第二电源电路连接；
所述控制电路的接地端与所述第一电源电路的地连接。
在一种可能的实施方式中，所述开关管控制的LED的另一端与所述第二电源电路的正电压端连接；
所述开关管的第二端与所述第二电源电路的地或负电压端连接。
在一种可能的实施方式中，所述开关电路中所述开关管的数量为两个，由所述开关电路控制的LED的数量为多个，其中，多个LED中部分LED被两个开关管中的第一个开关管控制，剩余LED被第二个开关管控制；
所述第一个开关管的第二端和所述第二个开关管的第二端均与所述第二电源电路的接地端连接。
在一种可能的实施方式中，所述第一个开关管控制的LED与所述第二电源电路的正电压端连接，所述第二个开关管控制的LED与所述第二电源电路的负电压端连接；
所述第二电源电路的正电压端的电压与负电压端的电压的绝对值相等。
在一种可能的实施方式中，所述第一个开关管为NMOS晶体管，所述第二个开关管为PMOS晶体管；发送给所述NMOS晶体管控制端的信号与发送给所述PMOS晶体管控制端的信号相同或者互补。
在一种可能的实施方式中，所述开关管控制的LED为一个LED，或者，为多个LED串联形成的LED串。
第二方面，本申请实施例提供一种电子设备，包括第一方面任一项所述的LED驱动系统以及液晶面板。
本申请实施例提供的LED驱动系统及电子设备，包括LED电路板，所述LED电路板包括LED驱动器和LED，所述LED驱动器包括控制电路和开关电路，所述开关电路用于控制所述LED的亮度，所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断，所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置，从而使得控制电路的接地端尽量远离LED回路，减轻LED大电流对控制电路接地端的影响，使得LED回路的接地弹跳尽量不干扰控制电路的电压，从而减少因接地弹跳引发的电路故障，提高设备工作的稳定性。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的一种应用场景示意图；
图2为本申请实施例提供的一种LED驱动电路的结构示意图；
图3为本申请实施例提供的一种LED驱动器的结构示意图；
图4为图2及图3所示电路的电流电压变化示意图；
图5为本申请实施例一提供的一种LED驱动系统的结构示意图；
图6为本申请实施例一提供的另一种LED驱动系统的结构示意图；
图7为本申请实施例二提供的一种LED驱动系统的结构示意图；
图8为图7所示LED驱动系统的电流电压变化示意图；
图9为本申请实施例三提供的一种LED驱动系统的结构示意图；
图10为图9所示LED驱动系统的电流电压变化示意图；
图11为本申请实施例四提供的一种LED驱动系统的结构示意图；
图12为图11所示LED驱动系统的电流电压变化示意图。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例中所使用的单数形式的“一种”和“该”也旨在包括多数形式，除非上下文清楚地表示其他含义。
取决于语境，如在此所使用的词语“如果”、“若”可以被解释成为“在……时”或“当……时”或“响应于确定”或“响应于检测”。类似地，取决于语境，短语“如果确定”或“如果检测(陈述的条件或事件)”可以被解释成为“当确定时”或“响应于确定”或“当检测(陈述的条件或事件)时”或“响应于检测(陈述的条件或事件)”。
还需要说明的是，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的商品或者系统不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种商品或者系统所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的商品或者系统中还存在另外的相同要素。
图1为本申请实施例提供的一种应用场景示意图。如图1所示，在显示设备中可以设置有LED和液晶面板，LED用于提供背光功能，图中的箭头表示LED发出的光可以作用于液晶面板上。LED驱动器与LED连接，能够控制LED的亮度。LED的数量可以为多个，多个LED发出的光与液晶面板显示的图像相配合，可以提高显示的效果。
图2为本申请实施例提供的一种LED驱动电路的结构示意图。如图2所示，在LED电路板(LED Board)上可以设置LED驱动器(LED Driver)和LED。本申请实施例以一个LED驱动器驱动2个LED为例来进行说明。两个LED分别记为D1和D2。LED由设置在驱动电路板(Driving Board)上的AC/DC(交流转直流)电路供电。
LED驱动器可以包括控制电路和NMOS(N-Metal-Oxide-Semiconductor，N型金属-氧化物-半导体)晶体管。所述控制电路可以为数字&模拟电路(Digital Circuit&Analog Circuit)。
晶体管的一端连接LED，另一端VSS_LED接地，LED与AC/DC电路连接，具有供电电压V_LED。当晶体管导通时，有电流经过LED，即流经LED的电流I_LED大于0；当 晶体管断开时，I_LED等于0。
晶体管的控制端与控制电路连接，从而控制电路能够控制晶体管的通断。控制电路由驱动电路板上的DC/DC(直流转直流)电路供电。具体的，控制电路的电源端VDD连接到驱动电路板上的DC/DC电路，控制电路的接地端GND连接到晶体管接地的一端VSS_LED，然后VSS_LED再连接到驱动电路板上的地。
可选的，LED驱动器可以通过PWM(Pulse Width Modulation，脉冲宽度调整)信号来实现LED的驱动。
图3为本申请实施例提供的一种LED驱动器的结构示意图。如图3所示，LED驱动器中，控制电路可以包括带隙基准电路、PWM输出电路、电阻R1和R2、运算放大器U1等。其中，带隙基准电路可以提供带隙基准，PWM输出电路可以输出PWM信号，从而对NMOS晶体管进行控制，调节D1和D2的发光状态。
与图2类似，LED的供电电压和电流分别为V_LED和I_LED，LED驱动器有一个电源端VDD，另外，LED驱动器中控制电路的接地端GND与晶体管的接地端VSS_LED在LED驱动器内部连接到一起，即VSS_LED＝GND。
在图2和图3所示方案中，当I_LED较大时，可能会导致接地弹跳，容易导致电路误动作。
图4为图2及图3所示电路的电流电压变化示意图。图4中的电压和电流变化对图2和图3均适用。如图4所示，t表示时间，流经LED的电流I_LED随着PWM信号的变化而变化。当出现PWM脉冲时，晶体管导通，电流I_LED为正；晶体管断开时，电流I_LED降为0。
当电流I_LED较大时，由于晶体管的接地端VSS_LED与驱动电路板的地之间有一定的距离，这段距离上的电阻会产生压降，导致VSS_LED大于0，而控制电路的接地端GND与晶体管的接地端VSS_LED相连，在电流I_LED较大时，GND处的电压也较大，导致控制电路产生接地弹跳。
在控制电路的VDD的电压不变时，GND的电压变化会导致VDD与GND之间的压差即图中的VDD-GND发生变化，容易导致控制电路出现故障，影响设备正常工作。
为了解决这一问题，本申请实施例提供一种LED驱动系统，将晶体管的接地端VSS_LED和控制电路的接地端GND分开。VSS_LED和GND不在LED电路板内连接，它们在远离LED板的地方连接在一起，这样，LED驱动回路的接地弹跳不会干扰控制电路的高低电平，从而保证电路正常工作。
实施例一
本申请实施例一提供一种LED驱动系统。图5为本申请实施例一提供的一种LED驱动系统的结构示意图。如图5所示，所述LED驱动系统可以包括LED电路板；
所述LED电路板包括LED驱动器和LED；
所述LED驱动器包括控制电路和开关电路；
所述开关电路用于控制所述LED的亮度；
所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断；
所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置。
其中，本申请实施例所述的电路板，可以是PCB(Printed Circuit Board，印制电路板)、玻璃(Glass)或者晶元(Wafer)。在LED电路板上设置有LED驱动器和LED。LED和LED驱动器的数量均可以为一个或多个，一个LED驱动器可以控制一个LED，也可以控制多个LED。所述LED可以为mini-LED或是普通的LED。
所述LED驱动器中，控制电路的接地端和开关电路的各个端可以在所述LED驱动器内部分离设置。本申请实施例所述的分离设置，是指不直接通过导线连接到一起，所述导线可以包括PCB上的布线。
具体来说，若所述开关电路不包括接地端，那么开关电路的各个端均不需要和控制电路的接地端直接连接在一起。若所述开关电路包括接地端，那么，所述开关电路的接地端与所述控制电路的接地端可以分离设置。
在所述LED驱动器内部分离设置的一种具体实现方案是，在所述LED电路板上分离设置。可以理解的是，由于LED驱动器设置在LED电路板上，那么，在LED电路板上分离设置，自然也就在LED驱动器内部分离设置。
可选的，在所述LED驱动系统还包括其它电路板的情况下，所述开关电路的接地端与所述控制电路的接地端可以在所述其它电路板上连接，尤其可以在提供电源的电路板上连接。
具体的，LED驱动系统可以包括多个电路板，LED驱动器和LED可以位于一层电路板上，其它电路可以位于其它电路板上，LED驱动器中的控制电路和开关电路的接地端可以在其它电路板上实现连接。
当然，所述开关电路的接地端和所述控制电路的接地端还可以在其它远离LED电路板的地方实现连接，例如，可以在LED驱动系统的壳体上连接。
图6为本申请实施例一提供的另一种LED驱动系统的结构示意图。图6所示方案与图5所示方案的不同之处在于，控制电路的接地端和开关电路的接地端可以在LED电路板上连接到一起。
如图6所示，在所述LED驱动系统中，LED电路板上设置有LED驱动器和LED，LED驱动器内的控制电路的接地端和开关电路的接地端和在LED驱动器内部分离设置，但是不必在LED电路板上分离设置。
具体的，控制电路的接地端和开关电路的接地端，可以在LED驱动器的外部连接到一起，然后连接到其它电路板上的地。在LED电路板的电阻较少时可以使用图6所示的方案，在电阻较大时可以使用图5所示的方案，从而实现更加灵活的电路设计方案。
本实施例提供的LED驱动系统，包括LED电路板，所述LED电路板包括LED驱动器和LED，所述LED驱动器包括控制电路和开关电路，所述开关电路用于控制所述LED的亮度，所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断，所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置，从而使得控制电路的接地端尽量远离LED回路，减轻LED大电流对控制电路接地端的影响，使得LED回路的接地弹跳尽量不干扰控制电路的电压，从而减少因接地弹跳引发的电路故障，提高设备工作的稳定性。
实施例二
本申请实施例二提供一种LED驱动系统。本实施例是在前述实施例提供的技术方案的基础上，将控制电路的接地端与开关电路的接地端在驱动电路板上实现连接。
具体的，所述LED驱动系统可以包括LED电路板；所述LED电路板包括LED驱动器和LED；所述LED驱动器包括控制电路和开关电路；所述开关电路用于控制所述LED的亮度；所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断；所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置。
进一步的，所述LED驱动系统可以包括驱动电路板；所述驱动电路板包括用于为所述控制电路供电的第一电源电路以及用于为所述LED供电的第二电源电路。
其中，所述第一电源电路可以为直流转直流电路，所述第二电源电路可以为交流转直流电路，满足控制电路和LED的不同供电需求。
所述开关电路的接地端与所述控制电路的接地端可以在所述驱动电路板上连接，能够在实现统一接地的基础上，有效减轻LED大电流对控制电路接地端的影响。
可选的，所述开关电路可以包括开关管，所述开关管包括控制端、第一端以及第二端；所述开关管的第一端与所述开关管控制的LED的一端连接，所述开关管的第二端与所述第二电源电路连接。所述开关管控制的LED的另一端与所述第二电源电路的正电压端连接；所述开关管的第二端具体可以作为接地端，与所述第二电源电路的接地端连接，从而形成回路。
图7为本申请实施例二提供的一种LED驱动系统的结构示意图。如图7所示，LED电路板上设置有LED驱动器和LED。LED驱动器包括控制电路和开关电路。所述开关电路包括开关管，所述开关管具体可以为图中的NMOS晶体管。驱动电路板上设置有第一电源电路和第二电源电路。
所述LED驱动器的端口可以包括控制电路的电源端VDD、接地端GND，还包括开关管的第二端VSS_LED以及用于与LED连接的第一端。
可选的，所述开关管为NMOS晶体管时，所述NMOS晶体管的栅极为与用于控制电路连接的控制端，漏极为用于与LED连接的第一端，源极为用于与第二电源电路连接的第二端。
在其它可选的实现方式中，所述开关电路也可以包括其它能够实现开关功能的器件，例如PMOS晶体管、三极管等。
本申请各实施例中，电源端可以是指用于输出或接收电源正电压的端口，接地端可以是指用于接地的端口。其中，控制电路的电源端VDD连接到第一电源电路的电源端，控制电路的接地端GND连接到第一电源电路的地。当然，所述LED驱动器还可以包括其它未示出的端口，例如通信端口等。
所述开关管控制的LED为一个LED，或者，为多个LED串联形成的LED串。在所述开关管控制多个LED的情况下，多个LED的正负极依次相接，串联形成的LED串，所述LED串的一端是指第一个LED的负极，另一端是指最后一个LED的正极。
在一个开关管控制两个LED的情况下，两个LED中的D1和D2串联连接。所述开关管的第一端与D2的负极连接，第二端VSS_LED连接到第二电源电路的地，D1的正极与第二电源电路的正电压端连接，从而形成闭合回路。
当开关管导通或者断开时，LED所在的回路导通或者断开，从而控制LED的亮灭。所述控制电路可以控制所述开关管的通断。具体的，控制电路与所述开关管的控制端连接，通过向所述控制端发送PWM信号来控制开关管的导通或断开。
当然，所述控制电路除了可以实现对开关管的控制以外，还可以用于实现其它功能，例如与控制器进行通信等等。本申请实施例中，LED驱动器中除了开关管以外的其它全部或部分电路可以被称为控制电路。
所述开关管除所述控制端以外的其它端均与所述控制电路的接地端GND在所述LED驱动器内部分离设置。当所述开关管的某一端例如VSS_LED需要连接到地时，可以在驱动电路板上与控制电路的接地端GND连接到一起。
可以理解的是，第一电源电路的地和第二电源电路的地将会连接在一起，因此，开关管的VSS_LED与控制电路的接地端GND分别连接到第一电源电路的地和第二电源电路的地，相当于开关管的VSS_LED与控制电路的接地端GND最终连接到一起。
图8为图7所示LED驱动系统的电流电压变化示意图。如图8所示，t表示时间，流经LED的电流I_LED随PWM信号而变化，在PWM脉冲期间内I_LED为正，在其它时间I_LED为0。开关电路的第二端VSS_LED的电压随着电流I_LED的变化而变化，在I_LED为0时，VSS_LED也为0；在I_LED为正时，VSS_LED升高为大于0，具体大小与VSS_LED到第二电源电路的地的阻值有关。
控制电路的接地端GND由于与开关电路的第二端VSS_LED分离设置，因此，控制电路的接地端GND的电压受I_LED的影响较小，其电压波动不大，约定于0。控制电路的电源端VDD的电压基本不发生变化，因此控制电路的电源端VDD与接地端GND之间的压差基本保持不变，能够提高控制电路工作的稳定性。
本实施例提供的LED驱动系统，包括LED电路板和驱动电路板，所述LED电路板包括LED驱动器和LED，所述驱动电路板包括用于为所述控制电路供电的第一电源电路以及用于为所述LED供电的第二电源电路，所述开关电路包括开关管，所述开关管包括控制端、第一端以及第二端，所述开关管的第一端与所述开关管控制的LED的一端连接，所述开关管控制的LED的另一端与所述第二电源电路的正电压端连接，所述开关管的第二端与所述第二电源电路的地连接，所述控制电路的接地端与所述第一电源电路的地连接，使得控制电路的接地端和开关电路的接地端在远离LED驱动器的驱动电路板上连接，能够进一步减小控制电路的接地端的电压变化，减少接地弹跳，提高系统的稳定性。
实施例三
本申请实施例三提供一种LED驱动系统。图9为本申请实施例三提供的一种LED驱动系统的结构示意图。本实施例与实施例二的不同之处在于，开关管的第二端VSS_LED不需要连接到地，即不需要为0。
如图9所示，LED电路板上设置有LED驱动器和LED，驱动电路板上设置有第一电源电路和第二电源电路。所述LED驱动器包括控制电路和开关电路。所述LED驱动器的端口可以包括控制电路的电源端VDD、接地端GND，还包括开关管的第二端VSS_LED以及用于与LED连接的端口。其中，控制电路的电源端VDD连接到第一电源电路的电源端，控制电路的接地端GND连接到第一电源电路的地。
开关管可以为NMOS晶体管，两个LED中的D1和D2串联连接。所述开关管的第一端与D2的负极连接，第二端VSS_LED连接到第二电源电路的地，D1的正极与第二电源电路的正电压端连接，从而形成闭合回路。
所述开关管除所述控制端以外的其它端均与所述控制电路的接地端GND在所述LED驱动器内部分离设置。
可选的，所述开关管的第二端VSS_LED可以不必连接到地，从而可以具有不等于0的电压。
本实施例中，所述开关管的第二端VSS_LED可以与所述第二电源电路的负电压端连接。本申请各实施例中，正电压端可以是指输出电压大于0的端口，负电压端可以是指输出电压小于0的端口。
可选的，所述第二电源模块的正电压端输出的正电压与所述第二电源模块的负电压端输出的负电压之间的差值可以等于所述LED正常工作需要的压差，从而保证LED被正常驱动。
进一步的，所述负电压端的输出电压可以与正电压端的输出电压互为相反数，所述第二电源电路输出的正电压可以为V_LED/2，输出的负电压可以为-V_LED/2，能够在保证压差的情况下简化电源电路，提高系统性能。
图10为图9所示LED驱动系统的电流电压变化示意图。如图10所示，t表示时间，流经LED的电流I_LED随PWM信号而变化，在PWM脉冲期间内I_LED为正，在其它时间I_LED为0。
开关电路的第二端VSS_LED的电压随着电流I_LED的变化而变化，在I_LED为0时，VSS_LED的电压为-V_LED/2；在I_LED为正时，由于有电流经过，VSS_LED的电压略大于-V_LED/2，具体大小与VSS_LED到第二电源电路的地的阻值有关。
由于开关管的第二端VSS_LED不再连接到地，自然不再连接控制电路的接地端GND，因此，控制电路的接地端GND在I_LED发生变化时基本不受影响，约定于0。控制电路的电源端VDD的电压基本不发生变化，因此控制电路的电源端VDD与接地端GND之间的压差基本保持不变，能够提高控制电路工作的稳定性。
本实施例提供的LED驱动系统，除了开关管的第二端VSS_LED的电压与实施例二中方案不同以外，其它器件的结构、功能、连接关系等均可以参见实施例二中的方案。
本实施例提供的LED驱动系统，所述控制电路的接地端与所述第一电源电路的地连接，所述开关管的第二端与所述第二电源电路的负电压端连接，从而开关电路不需要连接到地，即不需要为0V，这为电路设计提供了更大的自由度，开关管的第二端可以使用任意的电压，能够在提高系统稳定性的基础上根据实际需要设计开关管的电压，满足不同场景的应用需求。
实施例四
本申请实施例四提供一种LED驱动系统。本实施例与实施例二和三的不同之处在于，开关电路可以包括多个开关管，分别控制不同的LED。
具体的，所述开关电路中所述开关管的数量为两个，由所述开关电路控制的LED的数量为多个，其中，多个LED中部分LED被两个开关管中的第一个开关管控制，剩余LED被第二个开关管控制；所述第一个开关管的第一端和所述第二个开关管的第一 端均与LED连接，所述第一个开关管的第二端和所述第二个开关管的第二端均与所述第二电源电路的接地端连接。
进一步的，所述第一个开关管控制的LED与所述第二电源电路的正电压端连接，所述第二个开关管控制的LED与所述第二电源电路的负电压端连接；所述第二电源电路的正电压端的电压与负电压端的电压的绝对值相等。
图11为本申请实施例四提供的一种LED驱动系统的结构示意图。如图11所示，LED电路板上设置有LED驱动器和LED，驱动电路板上设置有第一电源电路和第二电源电路。LED驱动器包括控制电路和开关电路。控制电路包括电源端VDD和接地端GND，所述控制电路的电源端VDD连接到第一电源电路的电源端，控制电路的接地端GND连接到第一电源电路的地。
所述开关电路包括两个开关管，可选的，第一个开关管可以为图中的NMOS晶体管，所述第二个开关管可以为图中的PMOS(P-Metal-Oxide-Semiconductor，P型金属-氧化物-半导体)晶体管。
第一个开关管的第二端和第二个开关管的第二端连接，记为VSS_LED，VSS_LED连接到第二电源电路的地。
第一个开关管和第二个开关管控制不同的LED，分别记为D1和D2。其中，所述第一个开关管的第一端与D1的负极连接，D1的正极与第二电源电路的正电压端连接，第二个开关管的第一端与D2的正极连接，D2的负极与第二电源电路的负电压端连接，从而形成闭合回路。所述第二电源电路的正电压端和负电压端输出的电压分别为V_LED/2和-V_LED/2。
当第一个开关管导通或者断开时，D1所在的回路导通或者断开，从而控制D1的亮灭。同理，当第二个开关管导通或者断开时，D2所在的回路导通或者断开，从而控制D2的亮灭。
控制电路可以控制两个开关管的通断。具体的，控制电路可以与两个开关管的控制端分别连接，通过向两个开关管的控制端分别发送PWM信号来控制开关管的导通或断开。
可选的是，发送给所述NMOS晶体管控制端的信号与发送给所述PMOS晶体管控制端的信号相同或者互补。
具体的，当NMOS晶体管和PMOS晶体管的控制端输入同样的PWM信号时，两个LED的亮度变化是互补的，即，其中一个LED亮时，另一个LED不亮；当NMOS晶体管和PMOS晶体管的控制端输入互补的PWM信号时，PMOS晶体管和NMOS晶体管同时导通，两个LED的亮度变化是相同的。其中，互补可以是指高低电平互补，即一个信号为高时另一个信号为低。
可选的，所述第二电源电路输出的正电压可以为V_LED/2，输出的负电压可以为-V_LED/2，使得两个LED上具有相同的压降，保证各个LED的正常工作。
图12为图11所示LED驱动系统的电流电压变化示意图。如图12所示，t表示时间，流经LED的电流I_LED随PWM信号而变化，在PWM脉冲期间内I_LED为正，在其它时间I_LED为0。
开关管的第二端VSS_LED的电压随着电流I_LED的变化而变化，在I_LED为0时， VSS_LED的电压为0；在I_LED为正时，由于有电流经过，VSS_LED的电压略大于0，具体大小与VSS_LED到第二电源电路的地的阻值有关。
控制电路的接地端GND由于与开关电路的第二端VSS_LED分离设置，因此，控制电路的接地端GND的电压受I_LED的影响较小，其电压波动不大，约等于0。控制电路的电源端VDD的电压基本不发生变化，因此控制电路的电源端VDD与接地端GND之间的压差基本保持不变，能够提高控制电路工作的稳定性。
本实施例提供的LED驱动系统，除了开关电路包括两个开关管以外，其它器件的结构、功能、连接关系等均可以参见实施例二和三中的方案。
本实施例提供的LED驱动系统，开关电路中开关管的数量为两个，由所述开关电路控制的LED的数量为多个，其中，多个LED中部分LED被两个开关管中的第一个开关管控制，剩余LED被第二个开关管控制；所述第一个开关管的第一端和所述第二个开关管的第一端均与LED连接，所述第一个开关管的第二端和所述第二个开关管的第二端均与所述第二电源电路的接地端连接，所述第一个开关管控制的LED与所述第二电源电路的正电压端连接，所述第二个开关管控制的LED与所述第二电源电路的负电压端连接；所述第二电源电路的正电压端的电压与负电压端的电压的绝对值相等，从而通过不同的开关管控制不同的LED，并且各个开关管的第二端不影响控制电路的接地端GND，在减少电路误动作的基础上，增加了LED控制的灵活性。
在实际应用中，LED驱动系统的各个器件的电压和电流值可以根据实际需要来设计。可选的，控制电路的电源端VDD的电压值可以为1.8V～5V，V_LED可以为10V～80V，VSS_LED可以设计为0V或-V_LED/2，I_LED可以为1mA～120mA，PWM信号的频率可以为60Hz～4k Hz。
本申请各实施例中，所述开关电路可以包括一个或多个开关管。可以理解的是，所述开关电路的各个端可以包括所述一个或多个开关管的各个端。例如，所述开关电路的控制端可以包括开关管的控制端。在所述开关电路包括多个开关管的情况下，所述开关电路的控制端可能会有多个。
上述实施例给出了LED驱动的几种具体实现方案。在此基础上，可以根据实际需要来对电路进行适当的调整，例如将晶体管调整为三极管，将电源电路调整为其它类型的电源电路，增加更多的开关管等等。本申请实施例对此不作限制。
本申请实施例还提供一种电子设备，包括上述任一实施例所述的LED驱动系统以及液晶面板。所述LED驱动系统用于为所述液晶面板提供背光。
所述电子设备可以是液晶电视等任意具有显示功能的设备。
所述电子设备中各部件的结构、功能、连接关系均可以参见前述实施例，此处不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的设备和方法，可以通过其它的方式实现。例如，以上所描述的设备实施例仅仅是示意性的，例如，所述模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个模块可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或模块的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的模块可以是或者也可以不是物理上分开的，作为模块显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个单元上。可以根据实际的需要选择其中的部分或者全部模块来实现本实施例方案。
另外，在本申请各个实施例中的各功能模块可以集成在一个处理单元中，也可以是各个模块单独物理存在，也可以两个或两个以上模块集成在一个单元中。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (10)

  1. 一种LED驱动系统，其特征在于，所述LED驱动系统包括LED电路板；
    所述LED电路板包括LED驱动器和LED；
    所述LED驱动器包括控制电路和开关电路；
    所述开关电路用于控制所述LED的亮度；
    所述控制电路与所述开关电路的控制端连接，用于控制所述开关电路的通断；
    所述开关电路除所述控制端以外的其它端均与所述控制电路的接地端在所述LED驱动器内部分离设置。
  2. 根据权利要求1所述的系统，其特征在于，所述LED驱动系统还包括其它电路板；
    所述开关电路的接地端与所述控制电路的接地端在所述其它电路板上连接。
  3. 根据权利要求1或2所述的系统，其特征在于，所述LED驱动系统还包括驱动电路板；
    所述驱动电路板包括用于为所述控制电路供电的第一电源电路以及用于为所述LED供电的第二电源电路。
  4. 根据权利要求3所述的系统，其特征在于，所述开关电路包括开关管，所述开关管包括控制端、第一端以及第二端；
    所述开关管的第一端与所述开关管控制的LED的一端连接，所述开关管的第二端与所述第二电源电路连接；
    所述控制电路的接地端与所述第一电源电路的地连接。
  5. 根据权利要求4所述的系统，其特征在于，所述开关管控制的LED的另一端与所述第二电源电路的正电压端连接；
    所述开关管的第二端与所述第二电源电路的地或负电压端连接。
  6. 根据权利要求4或5所述的系统，其特征在于，所述开关电路中所述开关管的数量为两个，由所述开关电路控制的LED的数量为多个，其中，多个LED中部分LED被两个开关管中的第一个开关管控制，剩余LED被第二个开关管控制；
    所述第一个开关管的第二端和所述第二个开关管的第二端均与所述第二电源电路的接地端连接。
  7. 根据权利要求6所述的系统，其特征在于，所述第一个开关管控制的LED与所述第二电源电路的正电压端连接，所述第二个开关管控制的LED与所述第二电源电路的负电压端连接；
    所述第二电源电路的正电压端的电压与负电压端的电压的绝对值相等。
  8. 根据权利要求7所述的系统，其特征在于，所述第一个开关管为NMOS晶体管，所述第二个开关管为PMOS晶体管；发送给所述NMOS晶体管控制端的信号与发送给所述PMOS晶体管控制端的信号相同或者互补。
  9. 根据权利要求4-8任一项所述的系统，其特征在于，所述开关管控制的LED为一个LED，或者，为多个LED串联形成的LED串。
  10. 一种电子设备，其特征在于，包括权利要求1-9任一项所述的LED驱动系统以及液晶面板。
PCT/CN2021/123116 2020-11-03 2021-10-11 Led驱动系统及电子设备 WO2022095664A1 (zh)

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