LED dimming method

LED dimming method

  • CN 106,251,811 B
  • Filed: 08/12/2016
  • Issued: 04/24/2020
  • Est. Priority Date: 08/12/2016
  • Status: Active Grant
First Claim
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1. An LED dimming method is characterized in that an LED backlight source is provided with a plurality of LED lamps, the LED lamps are equally divided into N groups to form N series-connected lamp strings, and N light-emitting modules are formed on the basis of the N lamp strings;

  • n is an integer greater than or equal to 2;

    based on a multi-path switching mechanism, an MMI module is adopted to input a control instruction, and a controller is used as a main control unit;

    dimming of the LED lamp is realized by adopting a PWM dimming module;

    switching the light-emitting module by adopting a multi-selection one analog switch;

    a current detection circuit is adopted to detect current to realize current feedback and overcurrent protection;

    the control method comprises the following steps;

    the stepless constant-current dimming of the LED backlight source is realized according to the following steps;

    step 1;


    setting the channel selection number to be 1 and setting the duty ratio of PWM pulse to be 0.5;

    step 2;

    starting a timer;

    and step 3;

    when the timing is up, the controller generates a channel selection number;

    and 4, step 4;

    the one-out-of-multiple analog switch selects one path of light emitting module based on the channel selection number;

    and 5;

    generating a PWM pulse based on an input command of the MMI;

    an input instruction of the MMI is used for setting a duty ratio, and the controller generates PWM pulses according to the set duty ratio to realize stepless dimming;

    step 6;

    constant current controlThe current detection circuit is adopted to detect the current of the light-emitting module, the duty ratio of the PWM pulse is adjusted by the controller based on the detected current, and when the current exceeds a threshold value, the controller stops outputting the PWM pulse to realize LED constant current control and overcurrent protection;

    the current detection circuit comprises a measuring resistor Rx and a voltage detection module;

    the one-out-of-multiple analog switch is provided with N channels, N channel branch IO ends and a common IO end;

    the one-out-of-multiple analog switch is also provided with a channel selection end;

    the channel selection end is connected with an IO port of the controller;

    the controller outputs a signal to the channel selection end to control the conduction of any channel;

    the controller outputs PWM pulses to the PWM dimming module;

    the output end of the PWM dimming module is connected with a common IO end of the one-out-of-multiple analog switch;

    the positive terminals of the N light-emitting modules are respectively connected with an IO terminal with N channel branches of the one-out-of-multiple analog switch;

    the cathode ends of the N light-emitting modules are grounded through a measuring resistor Rx;

    the output end of the voltage detection module is connected with the data input port of the controller;

    when N is 4;

    the light emitting module is an LED light emitting module with an energy storage function;

    the light-emitting module comprises an LED lamp string, an energy storage inductor and a freewheeling diode;

    the LED lamp string is connected with the energy storage inductor in series to form a light-emitting branch circuit;

    the freewheeling diode is connected with the light-emitting branch in parallel;

    the voltage detection module is formed by connecting an amplifier and an A/D converter in series;

    the input end of the amplifier is connected with the measuring resistor Rx, and the output end of the A/D converter is connected with the controller;

    the PWM dimming module is a constant current driving chip;

    the controller is provided with a timer and a channel selection number generating unit;

    the channel selection number generating unit generates sequential integers or random integers between 1-N;

    the timer is used for generating a timing between 1 and 30 minutes;

    sequential integers refer to 1,2,3, …

    , N generated sequentially first, and after reaching N, the next is 1;

    the MMI module is a key or a touch screen;

    the controller is at least one of a digital PID controller, a DSP, an ARM processor, a singlechip, an FPGA or a CPLD.

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